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:::Valid points. High-power solid-state devices are encroaching, but have not ''totally'' replaced tubes in some applications. By 2025, I suspect you'll even see microwave ovens using switch-mode ]s instead of cavity resonators. And I am not alone in this speculation: Power Electronics magazine published a technical article on - so there's hardly any power- or frequency- regime that is "off-limits" for semiconductors. Pick up your favorite microwave or RF newsletter, and you'll see higher- and higher-power RF implemented in silicon. You are correct; the highest power systems haven't made the switch, yet. But it's a matter of time. Solid-state power is cheaper, safer, easier, better, more efficient, ... all the reasons that all other industry applications have switched to semiconductors. ] (]) 00:09, 10 January 2013 (UTC)
:::Valid points. High-power solid-state devices are encroaching, but have not ''totally'' replaced tubes in some applications. By 2025, I suspect you'll even see microwave ovens using switch-mode ]s instead of cavity resonators. And I am not alone in this speculation: Power Electronics magazine published a technical article on - so there's hardly any power- or frequency- regime that is "off-limits" for semiconductors. Pick up your favorite microwave or RF newsletter, and you'll see higher- and higher-power RF implemented in silicon. You are correct; the highest power systems haven't made the switch, yet. But it's a matter of time. Solid-state power is cheaper, safer, easier, better, more efficient, ... all the reasons that all other industry applications have switched to semiconductors. ] (]) 00:09, 10 January 2013 (UTC)
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::::<small>You are certainly correct in saying vacuum tube technology is obsolete for most applications - that is very obvious. However niche applications for tubes continue. IGBT's are inherently low frequency devices and will not replace magnetrons. If you read the article you linked to, you'll see they think 50 kHz is a good achievement. The triode valve method of measuring extra high voltages works well for short (microsecond) pulses too - nothing else does. Keit ] (]) 00:21, 10 January 2013 (UTC) </small>
::::<small>You are certainly correct in saying vacuum tube technology is obsolete for most applications - that is very obvious. However niche applications for tubes continue. IGBT's are inherently low frequency devices and will not replace magnetrons. If you read the article about switch mode power conversion you linked to, you'll see they think 50 kHz is a good achievement. The triode valve method of measuring extra high voltages works well for short (microsecond) pulses too - nothing else does. Keit ] (]) 00:21, 10 January 2013 (UTC) </small>
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Welcome to the science section of the Misplaced Pages reference desk.
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The best answers address the question directly, and back up facts with wikilinks and links to sources. Do not edit others' comments and do not give any medical or legal advice.
I recently woke up with pain in my finger. When I went to the doctor and had an x-ray, I learned that I had somehow broken it (probably overnight on the 31st). The doctor printed up a little document explaining what happened, but I didn't look at it until I had already left (because he explained very well verbally to me). On the document, the text "fracture radiographically appears acute in age" appears. What does the phrase "acute in age" mean? Google is of no help. Thanks! -- Tohler (talk) 00:03, 5 January 2013 (UTC)
Why be direct when they can be obscure? Like the lawyer who frets over your not writing a will, warning you that you could die intestate. ←Baseball Bugscarrots→ 05:56, 5 January 2013 (UTC)
Often laypeople get the urge to denigrate technical terminology, saying it could have been replaced with some lay terminology that doesn't actually mean the same precise thing. Maybe some of the above comments are an example of that. It looks to me like "acute in age" means "still in the acute stage, not yet in the sub-acute stage", in which case "age" refers to how far along it is in the expected sequence, not how recent in clock or calendar time it is (even though those would be imperfectly correlated). Note that the doctor was not being obscure, since he explained it well orally to the OP. Duoduoduo (talk) 14:07, 5 January 2013 (UTC)
"Acute" as a word means "sharp". In fact, it appears that the term "acute" is used in at least two somewhat different ways in the medical community. Kind of like how football uses the term "safety". ←Baseball Bugscarrots→ 16:00, 5 January 2013 (UTC)
Three actually, given there's "player safety" (prevention of bodily injury) as well as the positions and the scoring method. --Jayron3219:13, 5 January 2013 (UTC)
Yes. As in baseball, where there at least three usages of the term "hit" that come to mind. Or this fanciful definition of "rock": "To cause someone or something to swing or sway, by hitting them with it." ←Baseball Bugscarrots→ 20:45, 5 January 2013 (UTC)
I have no quarrel with "acute in age", now that I understand it; but I would like to know how "bilateral upper extremities" is better than "both arms", or why "infant is status post negative rule out sepsis" shouldn't be reworded. —Tamfang (talk) 06:13, 1 July 2013 (UTC)
I am not quite so sure of the reason for this struggle to explain away "acute in age". I went to the emergency room thinking I had broken my big toe. The doctor returned and said, yes, the toe was broken, and started manipulating the second one. I complained he had the wrong toe. Then, after looking at the exray again, he realises it was an old, healed break. Obviously he could tell on looking that the break was no longer acute in age. μηδείς (talk) 17:09, 6 January 2013 (UTC)
Science Olympiad
my teacher is not able to help me with these because we don't have any astronomy class in my school. I got stuck on number 27, 14, 15. see here. anskey, I got the answers but that doesn't mean I know how to do them. I need help on show me how to do it like what formula do I need to use, what can I tell from the result after calculating the formula, how do I interpret that? This is not homework as obvious.174.20.15.246 (talk) 01:27, 5 January 2013 (UTC)
I still don't get it. Let take a look at the problem. "Galaxies X and Y appear equally bright in the night sky. When a radio spectra of both galaxies are taken, the 21cm line of galaxy X is twice as wide as that of galaxy Y." So the key answer tells me the correct answer is galaxy X. Which means galaxy X must be further from Earth than galaxy Y so that means they have the same apparent magnitude but X has higher absolute luminosity (related to absolute magnitude). I have looked through Tully–Fisher relation but unable to find out any formula to use to figure out anything. Can someone please give me an example calculation?174.20.15.246 (talk) 07:42, 6 January 2013 (UTC)
From the linked article "roughly speaking, luminosity is proportional to velocity to the fourth power." Dauto (talk) 15:54, 6 January 2013 (UTC)
Lever frame
On British railroads, the levers in a lever frame are (well, used to be) color-coded as follows: Red -- Home signal; Yellow -- Distant signal; Black -- Railroad switch; Blue -- Facing point lock (locks corresponding switch in place); Brown -- Level crossing gate; White -- Spare. Does anyone know what were the corresponding color-coding conventions in France and Germany in the 1940s? Thanks in advance! 24.23.196.85 (talk) 05:26, 5 January 2013 (UTC)
Any ideas? Oh well, I guess I can just use the British color-coding in the signal box scene -- nobody's likely to notice, right? 24.23.196.85 (talk) 05:47, 6 January 2013 (UTC)
(Sorry to be so slow in getting you an answer...)
This page looks like it might be of help - the photos of the interiors of signal boxes in France look VERY different - not just the color coding. The section on german boxes says that the entire signalling system was different - and goes into the color coding some. SteveBaker (talk) 20:53, 8 January 2013 (UTC)
Thanks! I'm writing a scene where the Maquis are trying to switch the tracks at a junction in order to put a German ammo train on a siding rigged with explosives and blow it up -- so this is actually more info than I really needed, because they definitely won't be using the signal apparatus (in fact, the reason I asked was to see how they could switch the tracks without also changing the signal). And the part about the German signal box will come in handy near the end of the book, where the same Maquis team (which has parachuted into the Hurtgen Forest on a special mission) has to stop a prisoner train (by flipping the signal to "Stop") so they can take it over and infiltrate a secret German underground chemical plant. :-) 24.23.196.85 (talk) 03:06, 9 January 2013 (UTC)
Maybe in cases where research and development budgets are being cut. In my company, R&D is actually expanding. Companies figure R&D is vital for future competitive advantage. ←Baseball Bugscarrots→ 15:54, 5 January 2013 (UTC)
Yes, smart companies may actually increase R&D during a recession, as the business cycle is such that they might have new products ready to go just when the next boom starts. StuRat (talk) 21:18, 5 January 2013 (UTC)
Well those R&D are not actually for the sake of science, just for the profit they will be making. No profit = no R&D. Hard to blame them, everyone wants to make money... That's why they are companies not scientists. It's true that those new products from the companies may benefit the society later on. But the researches just for the sake of science without caring about its value must be declining because people don't interest in it especially in hard time. An example would be NASA.174.20.15.246 (talk) 07:21, 6 January 2013 (UTC)
Regarding science (engineering may be quite different): I confess I don't really know, but I haven't heard of any funding cuts to research in Australia. I'm doing a PhD on a scholarship, so I might have heard if anything was going down (I get to hear some of the goss, not the informed analysis). Government funding for research seems to be relatively recession-proof, since the government doesn't have to respond directly to an economic shockwave. It does have to take the economy into account, but it can take its time, unlike a commercial enterprise. It isn't, after all, in direct competition with a rival government trying to move in on its turf, at least not usually. IBE (talk) 19:14, 6 January 2013 (UTC)
Whenever the economy is bad, it's true that the government is not directly affected but it does affect the government somewhat. Let say everyone is making less money so that's mean the government will get less money from tax. When they have less money, there is no way they can keep up funding any research at the cost before. There got to be some cuts in the government spending or maybe they will cut a bit of everything.174.20.15.246 (talk) 20:25, 6 January 2013 (UTC)
This can't be totally wrong, but there's a lot more. Australia spent a lot of money trying to keep itself out of recession, as described here. I'm not an economist, but governments work slightly differently to corporations, and the money supply isn't a given. IBE (talk) 23:43, 6 January 2013 (UTC)
What the article linked by BeenEmotional doesn't spell out is how the Australian Government was able to spend this vast amount of money (which incidentally was largely wasted on projects with little or no economic return and lots of corruption) is that they had two sources: 1) a large surplus left over from when they took over from the opposition party, and 2) they borrowed vast amounts from China. This is directly equivalent to a private company or private individual on hard times spending their bank savings down at the casino, and then borrowing from a bank to continue down at the casino. In other words, short term, the amount of money about is proportional to the stupidity of politicians, and in the long term the crunch will come. The leader in this stupidity, Prime Minister Rudd, got the sack as he was completely on the nose. ADisgustedAssie 124.178.183.98 (talk) 01:28, 9 January 2013 (UTC)
sleeping with makeup on -- does your skin really need the oxygen?
I am transgender, but I also study biochemistry, so I'm always skeptical of the skincare industry. I like to leave makeup on because I can still wake up looking female (especially if I am sleeping with someone) but I wonder (despite what I read on the internet) whether this is really all that bad. Your epidermis isn't really alive, right, and all the alive parts get enough oxygen from their blood?
Not a request for medical advice, more of an inquiry of whether there are skin cells (that are alive) that need oxygen from the exterior. 72.229.155.79 (talk) 18:43, 5 January 2013 (UTC)
No, they don't need oxygen, or you couldn't wear a bandage for very long. The problem is that some chemicals will irritate or will block pores if left on too long. You can see if the product has a tollfree number to call for advice. μηδείς (talk) 18:53, 5 January 2013 (UTC)
Googling the issue, it seems that if the oil/sebum oxidises that it would polymerise and cause blackheads/whiteheads? Would foundation do the same? Trying to get a scientific perspective, I am SO skeptical of the skincare industry and cleansers. I use generic moisturisers, not brand-name ones. 72.229.155.79 (talk) 19:22, 5 January 2013 (UTC)
Blocking pores doesn't stop sweat getting out (I can sweat quite happily through full makeup), but it does stop the natural progression of sebum. It's possible then that the pores can get infected and lead to comedones and blackheads. --TammyMoet (talk) 19:26, 5 January 2013 (UTC)
Yes, and sebaceous cysts are quite nasty. Depending on where you are located there are probably cosmetologists, dermatologists, and other crossdressers who can help. NYC has no end of such resources. μηδείς (talk) 19:38, 5 January 2013 (UTC)
Thick enough make-up can stop sweat, and, if it covers a large portion of the body, this causes thermal distress and possible heat-stroke by denying the body the ability to cool itself. Mythbusters did an episode on this, where they painted one of them gold. Presumably your make-up isn't that thick or widespread. Also, skin does need access to air, not so much for oxygen for your cells as to dry it off. Skin under bandages eventually gets white and puffy, with the white from lack of sunlight and the puffy from the inability to air out. StuRat (talk) 21:11, 5 January 2013 (UTC)
Jill Masterson in Goldfinger supposedly died of "epidermal suffocation" by having her entire body covered in gold paint. She supposedly would have survived if the culprit had left only a small circle at the base of her spine unpainted. How scientifically accurate this is, I can only guess. -- Jack of Oz01:59, 6 January 2013 (UTC)
Well, according to Mythbusters, there was one scientifically accurate thing in Goldfinger -- the tire slashers on 007's Austin-Martin. 24.23.196.85 (talk) 08:05, 6 January 2013 (UTC)
Would it be possible to take a powdered ceramic like glass and some powdered metal, mix them finely, and sinter it into a single piece? If so, what kinds of properties would it have, and would such a thing have a name? If not, then what would happen if you tried it? Rabuve (talk) 20:55, 5 January 2013 (UTC)
If ceramics are metal oxides, and the exposed surfaces of any metal object oxidize to some extent under normal conditions, isn't every metal object, to some extent, a metal and a ceramic? Or perhaps this is very silly was of looking at things and missing out on some important point. DRosenbach06:22, 7 January 2013 (UTC)
Pineapple pee
I ate two large cans on pineapple yesterday, and today my urine smells like pineapple. So, is there some characteristic, fragrant component of pineapple that comes through, unchanged, in urine, just like in asparagus ? StuRat (talk) 21:38, 5 January 2013 (UTC)
There is an enzyme in pineapples that is known as bromelain. Some people believe that it offers urinary, digestive and anti-inflammatory effects. I doubt that it's the whole story behind the smell, but it could be a start. EricEnfermero01:49, 6 January 2013 (UTC)
In my searching, ethyl butanoate appeared most frequently (and our article even mentions that the compound smells like pineapple). In the medical literature PMID21694674 prominently mentions a similar compound, ethyl 2-methyl butanoate. Not sure about absorption and urinary excretion, but it seems plausible. -- Scray (talk) 04:29, 6 January 2013 (UTC)
January 6
Freezing water
What other measures to lower freezing temperature of water beside increasing pressure and adding salt? I observe moving water also will not easily freeze, is it because of the movement? How do you explain this? Is the amplitude of the wave and speed of wave also a factor? Any other factors? Thank you. roscoe_x (talk) 01:57, 6 January 2013 (UTC)
Lack of nucleation sites for ice crystals to form will also allow the water to get below freezing temp before it actually freezes. Once it starts, though, it will freeze even quicker than normal. There are also any number of things you can add to lower the freezing temperature, such as alcohol or ethylene glycol (antifreeze). StuRat (talk) 02:25, 6 January 2013 (UTC)
Generally, anything that dissolves in any substance (such as water) will lower that substance's freezing/melting point. StuRat has mentioned the ones that are commonly used to lower the melting point of water. Depending on the concentration of the substance dissolved, cooling a liquid may take it thru a paste or slush stage (a eutectoid mixture) until lowering the temperature still further cause it to freeze solid. This is essentially the same as dissolving tin in lead to make solder - the melting point is lower than that of both pure tin and pure lead.
With moving water, the key is not the overall velocity of the water or the speed of waves - the key is sheering and turbulence. By sheering I mean that one part of the water is moving faster than anothe part. If water is moving, the speed at which it is moving and the roughness of the surfaces surrounding it may induce turbulence, increasing local sheer. Pressure inhibits it. Sheering breaks newly forming crystal bonds around the points of nucleation that StuRat mentioned.
I read the article on flourescent lights but could not find the answer. Is turning a flourescent light off and on frequently (as when entering/exiting a room) less energy efficient than simply leaving it on for longer periods of time? Does it take more energy to "warm up" a flourescent light than just leaving it on? 99.250.103.117 (talk) 04:09, 6 January 2013 (UTC)
It is less energy efficient in theory as when you turn it on, the tube has to be started. During starting, the starter device sends heating current through the heaters in each end of the tube, and little or no light is emitted by the tube. In practice it would be difficult to measure the impact of any reasonable rate of switching on and off. The starting phase should be a second or less. Be aware though that if you do switch flouros on and off frequently, the incresed thermochemical wear on the starter and on the heaters inside the tube will noticably shorten the life of them. Wickwack 124.178.53.163 (talk) 04:21, 6 January 2013 (UTC)
(edit conflict) The break-even point for leaving the fluorescent light on is 23 seconds. That is, the energy needed to "power up" a fluorescent light (the long straight tube kind) is equivalent to leaving it on for 23 seconds. So, unless you plan to turn it off for less than 23 seconds, you should turn it off when you leave the room. This isn't true for CFLs, where break-even time is something like 0.015 seconds, which I think is faster than you can flick the switch on and off. --Jayron3204:22, 6 January 2013 (UTC)
Citation or explanation please. Many types of CFL, while they start immediate upon switching on, start at rather low brightness, and take several minutes to come up to full brioghtness. Is the electricity consumption proportionaly reduced during the several minute "warm up" phase? I rather suspect it's full current right from the start, but phosphor internal coating that converts the internally generated spectral light into white light has to warm up. If that is so, there is no breaking even point. Floda
Note that the current loop measurement method used by MythBusters is not valid, as it ignores power factor. A device powered from AC may draw a large current without using much energy if the current is not in phase with the voltage.
That's fine. Do you have any alternative data? --Jayron32 05:15, 6 January 2013(UTC)
I more or less asked you that. The data you linked is flawed because they used an invalid method, as I said. There may well be a break even point with both normal and compact tubes (CFL), though I doubt it for CFL. I have no alternative measured data. Floda60.230.240.191 (talk) 08:32, 6 January 2013 (UTC)
The larger fluorescent fittings that still use a heater will draw current in phase with the voltage initially for the heating element, but the current after "striking" will be partly out of phase with the voltage so a current measurement over-estimates the power consumption (perhaps by 50%, depending on the phase angle?), so the break-even time will be longer than calculated. Adding this to the wear on starting, I would suggest that it is probably sensible to leave fluorescent lights on if the off period would be less than a few minutes, (perhaps three to five) but this is only an estimate, and others might have different opinions. The exact time will vary with the cost of electricity and replacement parts. I don't know of any thorough research which would include the shortening of tube, starter and choke lifetime. Dbfirs16:09, 6 January 2013 (UTC)
This is purely anecdotal, but I can confirm from my several years' working in the Facilities Maintenance sector that switching lights on and off is widely thought to shorten significantly the life of fluorescent tubes, and also cause some degree (perhaps insigificant, perhaps not) of deterioration in the associated switches and wiring.
In large office and manufacturing buildings and complexes, the cost of replacing a burnt-out tube (or starter, or other component of the light fitting or circuit) is surprisingly high – you have to factor in not only the chain of bureaucracy involved in getting a light changed (which might ultimately involve more than a dozen individuals, with attendant overheads) but often also the cost of cherrypickers and operators, or scaffolding erection and removal, to reach the light fittings, and the closure of areas for safety reasons.
Because of these factors, there is/was a school of thought that it's cheaper to leave the (relatively efficient) tubes on permanently, and office staff might not even have access to on/off switches. Certainly it's common practice to go itno a given building every year or two during planned "down-time" and change all the tubes for new, whether working or not. {The poster formerly known as 87.81.230.195} 84.21.143.150 (talk) 17:36, 7 January 2013 (UTC)
I'm confused. Are you proposing that power a factor, where current and voltage are out of phase, is more efficient? I don't think this is the case. The difference between kVA and kW is lossy unless they are equal. The generator absorbs this energy and it is wasted as heat. --DHeyward (talk) 05:31, 8 January 2013 (UTC)
Power factor is defined as the ratio of dissipation to current x voltage, curent in amps, voltage in volts dissipation in watts. Where the ratio is less than unity, indicating the dissipation is less than amps x volts, it DOES NOT mean the difference is lost in the generator as heat. Note that power factor is made lower than unity if the current and voltage is not in phase, but that is not the only cause of PF less than unity. It also results from harmonics in the current. It is possible DHeyward has ben confused by texts stating that loads with low power factor (known as reactive loads) absorb and return energy during each cycle (20 millisec in a 50Hz system). This energy just shuttles back and forth and is not inherently lost as heat anywhere. A system having diffrent kVA and kW is NOT lossy for that reason, however, the increased current does cause extra minor loss in wiring. See http://en.wikipedia.org/Power_factor
Electricity meters are constructed so that they only sense the in-phase part of the current and thus only register the true power used (kW) regardless of any increased current due to low power factor. Keit124.182.27.187 (talk) 11:50, 8 January 2013 (UTC)
The above is correct (you get metered/charged for actual power, not apparent power), but Power factor does not say that wiring losses are minor. It implies that they are major: "if the load power factor were as low as 0.7 ... the losses in the circuit would be doubled" --Guy Macon (talk) 18:43, 8 January 2013 (UTC)
The losses can be made as small as you like by making the conductors/wiring heavy enough. Yes, a PF of 0.7071 (root 2) will double the wiring losses, but doubling (say) 1% is only 2%. It is quite unlikely you would have losses amounting to as much as 1% in lighting circuits. Keit 124.182.145.124 (talk) 01:38, 9 January 2013 (UTC)
Thanks for the link. Twenty minutes is longer than I expected, but is based on energy costs much lower than mine. Dbfirs09:09, 8 January 2013 (UTC)
The nice part is that you can plug your energy and bulb costs into the equation and get a definitive answer for your particular situation. When I did it I added my labor costs to the bulb costs by asking myself how much it is worth to me to not store an extra tube, not change an extra tube, and not discard an extra old tube. CFLs gave me a different number because they are easier to store, easier to change, and my local utility regularly subsidizes them at a dollar each. --Guy Macon (talk) 18:43, 8 January 2013 (UTC)
Since it is defined as a sensation in one sense that is triggered by another sense (eg perception that sounds are coloured), then, by definition the senses must be involved. Clarify what you are after - just what do you mean by "physically mess with the senses"? Do you mean externally activating a sense? Or physically altering brain circuitry? Floda60.230.240.191 (talk) 05:10, 6 January 2013 (UTC)
(edit conflict) What do you mean by your question? Synesthesia is a condition related to perception, in that a person who receives a signal at one sense perceives that signal in other senses (i.e. when they see a color like "green", they also believe they smell a specific smell). It should be noted that this is a "brain wiring" thing, perceiving a smell when you see the color green doesn't mean that there is any chemical stimulation of the receptors in your nose. So I don't know what you mean by "physically mess with the senses". There is no physical stimulation of the senses in synesthesia. If there was physical stimulation of a sense causes the perception, that's just normal sensations. --Jayron3205:13, 6 January 2013 (UTC)
Sure it happens in the brain, not the retina/cochlea/taste bud etc. but it doesn't seem that way to the sense-user.
Anyway, I think for most people, what color is the first note of Fur Elise or what pitch is 80 degrees Fahrenheit is a nonsense question - it is to me. What would you call a (sane) person who has an opinion without the actual sensation? Maybe there could be a third class of person who's even closer and just imagines the sensation? Sagittarian Milky Way (talk) 06:19, 6 January 2013 (UTC)
In other words, you want a word for someone who pretends that a musical note has a color, not who actually experiences that? I have a few words, but they're probably not appropriate for this forum. --Jayron3206:26, 6 January 2013 (UTC)
I think Jayron is insinuating that some reports of synaesthesia are outright lies; this has almost certainly occurred, and confounds any actual effort to sincerely study the actual phenomenon. As our article elaborates, objectively verifying any report is non-trivial. It is plausible that all reports of synaesthesia are "lies." Perception is a very difficult thing to quantify and measure objectively; it is not necessarily clear what it even means to "lie" about perceiving something. Nimur (talk) 19:14, 6 January 2013 (UTC)
No, I didn't insinuate that. I never used the word lie. SMW stated that there's a class of person who merely imagines that they have a sensation. I merely responded to his statement thereof. I have no feelings whatsoever that any genuine synesthesia does or does not occur. It is not my place to care one way or the other. --Jayron3219:26, 6 January 2013 (UTC)
I don't think Jayron was insinuating that some reports are lies -- I think he was insinuating that the OP was insinuating that. And (OR here, believe me or not) it is certainly not plausible that all reports of synaesthesia are "lies." For as long as I can remember (presumably back to sometime in my childhood) I've seen specific colors when I've encountered specific numerical digits, letters, days of the week, or months of the year. Moreover, I'm aware that the color that goes with a particular digit, etc., is invariant over the span of decades. And that's how it can be verified -- ask someone detailed questions about the connections, and then ask them again years later. Researchers have done that, and they have found stability of the associations. Duoduoduo (talk) 19:32, 6 January 2013 (UTC)
Associating certain numbers and colors (which I myself do) is different from actually sensing certain colors when one perceives certain numbers or letters. I don't do the latter--so I don't consider myself synaesthetic. But my associations between such colors and symbols have been very stable over the years. Given the nature of consciousness, I find it hard to deny that certain people do actually see the letter a as red, e as green, or s as yellow, in the way that I associate those things. μηδείς (talk) 22:25, 6 January 2013 (UTC)
Medeis, I think that what you've described for yourself, if I understand it correctly, is exactly what synaesthesia refers to. It's not looking at this "5" and seeing it as something other than the black that actually appears on the screen -- rather, if someone says "think of the number "5", you see the "5" in your mind colored a certain way. Is that what you have? Duoduoduo (talk) 16:16, 7 January 2013 (UTC)
How long will blood stain and semen stain persist, respectively?
It can be identified forever. However, if you go to the police now and show genuine regret, you will probably receive a lighter sentence. I have taken the liberty of forwarding your IP and address information to your local precinct. Please show some guilt and go to them yourself - and good luck. 178.48.114.143 (talk) 15:57, 6 January 2013 (UTC)
I don't think they have "precincts" where he comes from. Also, I don't think you have his IP address. Finally, there are legal methods of producing blood and semen stains. --Demiurge1000 (talk) 16:17, 6 January 2013 (UTC)
According to Blood residue blood stains have been identified on 100,000-year-old stone tools. There are some references in the article that looks promising if you want to know more. However, I guess that the best answer is "it depends" on the surface, exposure and what attempts are made to wipe it off. Sjö (talk) 16:52, 6 January 2013 (UTC)
a question for you evolutionists here. Why did people evolve to feel "hot"? Was anything in the natural environment hot? (Before the man-made invention of fire). I mean, outside of things that are electric or fire, which had not been invented, I can't think of anything we would touch.
Or would you say that man's sense of "hot" evolved since Prometheus? (being metaphorical, obviously - I know someone actually invented fire, just don't know when.) thanks. 178.48.114.143 (talk) 15:15, 6 January 2013 (UTC)
This really does not explain why organisms in the extreme latitudes would have developed a sense of "hot", since in the extreme North and South nothing is hot, ever. Yet Penguins do feel that. Why? Just in case of being transported to a Manhattan zoo? Clearly there is no evolutionary force here, and it is a lot more obvious that it was just designed this way. However, I am trying to keep an open mind and welcome your evolutionist answers as well for consideration - indeed, it is what I came here for. 178.48.114.143 (talk) 15:56, 6 January 2013 (UTC)
In fact, that is quite a neat demonstration of the fact that they descended from an ancestor who lived in a warmer climate, for much the reason that all cave fish have eyes - they are descended from a common anscestor to whom eyes would have been useful.--GilderienChat|List of good deeds16:09, 6 January 2013 (UTC)
Your assumption is simply false, fires do occur at the polar latitudes and they do have summers during which one can get sunburnt and when dark surfaces can heat enough in the sun to cause burns.
Also, note that the word "hot" is relative. What a penguin detects as hot would presumably be relative to the cold temperatures it is used to; in fact what the penguin feels is hot could be considered by a tropical creature to be cold. So, your question really boils down to "why can people/penguins detect changes in ambient (surrounding) temperatures". So, the supposition, from an evolutionary lens, is that it would be advantageous for creatures to feel something hot enough to burn it, since those that could not would presumably be killed or injured, reducing their ability to compete. Or if you're not limiting feeling "hot" to feeling burning, then presumably, creatures who could feel "hot" and "cold" would have an advantage over those who could not in terms of energy efficiency: warm-blooded creatures could maintain homeostasis better (less energy wasted shivering to create heat, less fluids wasted sweating to cool off), while cold-blooded animals would be able to find environments with suitable amounts of energy for them to function well, without extreme heat which would also be detrimental to their health. Brambleclawx18:04, 6 January 2013 (UTC)
There are obvious advantages to knowing ambient temperatures for both warm and cold blooded animals; it is necessary for homeostasis and would have an obvious differential survival rate for creatures that evolved over periods of time that included massive temperature fluctuations, among other hazards. The ability to detect temperature is much older than Homo sapiens, obviously — this is not a capability that we specially evolved, it is part of the general mammalian nervous system toolkit that evolved a long time earlier. As for feeling intense heat, like fires, that's not so much a detection of "heat" so much as it is a detection of pain. This page discusses the biology of this a bit. The neurons that fire in response to putting your hand on a very hot surface are not specialized to that perception. --Mr.98 (talk) 19:01, 6 January 2013 (UTC)
I would add that asking "Why did anything evolve anything?" kind of misses the point of how evolution works. Evolution doesn't have a specific purpose or "goal". Further, not every observable trait even has an evolutionary "purpose", a lot of traits are simply by-products of the evolutionary process, they could be 'correlated or associated with another trait that evolution did select for, or it could even be an inevitable or unavoidable consequence of some physical or biological factor. Why did we evolve to die when we loose a lot of blood? Well, we didn't, we have blood and we can't survive without it, we didn't "evolve" this trait, it's an unavoidable consequence based on our biology. The second mistake is to say why did PEOPLE evolve to feel hot? Clearly people DIDN'T evolve to feel hot, that is a trait passed down from at least our fish ancestors if not much earluer. There is obviously a very close relationship between neurons and nerves and heat receptors, it seems at some fundamental level they are related and I would even hazard a guess that maybe it's not even possible to have a brain made of neurons that can't feel heat. Vespine (talk) 05:50, 7 January 2013 (UTC)
An obvious follow-up question would be "Are there any animals which can sense changes in temperature, but lack a 'this is too hot. dangerous. Flee!'-response, on account of such situations being nearly non-existent in their natural environment ?" 157.193.175.207 (talk) 08:13, 7 January 2013 (UTC)
Except that the lede of that article says "According to contemporary biologists the premise of the story is not literally true". Duoduoduo (talk) 20:09, 7 January 2013 (UTC)
on the other hand, before getting down this far, regarding the discussion re humans or their ancestors experiencing fire, the first thing that leapt to mind was "not in our water dwelling ancestors". maybe that reasoning is the source of the boiling frog meme? Gzuckier (talk) 23:04, 9 January 2013 (UTC)
I still think this line of questioning is barking up the wrong tree. There is no such thing as a bilogical system without at least some heat, even at the extreme latitudes. Well hot is the same type of thing as warm, the difference is scale, not type. So if you can feel warmth, you can feel heat, I don't see the mystery. Did we evolve to feel a "vacuum", I'm sure we didn't, but I bet you would feel it if you were exposed to it. Vespine (talk) 02:55, 8 January 2013 (UTC)
People seasonally adapt to temperature just as they adapt altitude. Climbers for Mount Everest double their RbC at base cap and is why they "acclimate" for three weeks. As for heat, you will notice that people tend to put jackets on earlier in the fall and take them off earlier in the spring. This is because the body continually adapts to external temperature and grow capillaries near the surface in summer and they die off in the winter. 60F in March is a lot warmer that 60F in September. Feeling hot is that the body is not shedding heat fast enough and the actions to cool down protects organs from damage. --DHeyward (talk) 05:41, 8 January 2013 (UTC)
Moon and milk
Which country's astronauts landed on moon first - USA or USSR ? What were their names ?
Is it true that cream (upper layer) of milk contain more nutrients than the milk ? When water is heated it slowly starts changing into vapor, but when milk is heated it overflows the container (unlike water). Why ? 106.212.34.233 (talk) 18:50, 6 January 2013 (UTC)
Depends on which nutrients. Here is heavy cream and here is whole milk. It appears that some nutrients are more abundant in cream, and others in milk, per serving size. For 2b, the reason that milk boils over is that the stuff in the milk provides many nucleation sites for bubbles to form, so when it boils, you get millions of really tiny bubbles. These bubbles take up a lot of space, which causes the milk to "boil over" such that pure water (which has no real nucleation sites, so forms larger, and less numerous, bubbles) does not. --Jayron3218:57, 6 January 2013 (UTC)
Actaully, I bet boiling milk is more complicated then surface tension. I don't believe the surface tension of milk is very different to that of water, milk is very watery and extremely easily miscible with water, I don't think that would be the case if their surface tensions were dissimilar. What is dissimilar however is that milk contains proteins, I have no reference, but i suspect proteins would be responsible for ease with which milk boils over. Vespine (talk) 05:39, 7 January 2013 (UTC)
Agreed, and this holds the bubbles together long enough for the pot to boil over. Also note that this can happen with other foods, like pasta, presumably due to a similar mechanism causing the formation of foam. StuRat (talk) 21:07, 7 January 2013 (UTC)
I've personally observed this with rice -- the starch dissolves in the hot water and greatly increases the viscosity and surface tension (in fact, the sharp increase in viscosity near the end is the sign that the rice is just about ready). 24.23.196.85 (talk) 05:02, 8 January 2013 (UTC)
Questions About Pregnancy
I've got a couple of questions about pregnancy. Please do not interpret my questions as offensive or misogynistic, since that is not my intention at all. I'm simply trying to learn more info about this topic.
Does pregnancy affect a woman's emotions and to what extent? Also, does the part of the brain/mind that causes us to think rationally work the same way when a woman is pregnant in comparison as to when she is not pregnant?
Yes, there are emotional changes that are common with pregnancy. According to the Mayo Clinic, it's normal for pregnant women to feel delighted, anxious, exhilarated, exhausted and stressed, and have bouts of weepiness and/or mood swings, which can sometimes be severe or intense. You could also just ask a woman who is or has been pregnant (which is most women) how it feels. Red Act (talk) 20:40, 6 January 2013 (UTC)
How does pregnancy feel? Believe me it feels different. It was the first sign I experienced - I simply felt different. Just don't ask me to say exactly how I felt different though - I was never pregnant for long enough to quantify it. --TammyMoet (talk) 21:12, 6 January 2013 (UTC)
Tangential velocity of galaxies
I remember reading some time ago that while it is easy to measure the radial velocity of a galaxy wrt the Milky Way, a galaxy's relative tangential velocity cannot be measured at all. 1) Is this true? 2) If so, what's the reason? and 3) Would such measurements be of any use? 65.92.7.202 (talk) 22:30, 6 January 2013 (UTC)
The links in Catslash's answer doubtless address 1) and 2) adequately but perhaps not 3). Re this: knowing the real space velocities of galaxies would be of some interest in that it would help to confirm whether or not a given galaxy was gravitationally bound to its nearest neighbours (as in, for example, the Local Group). This in turn might shed light on the past history of those close neighbors' formation – presumably from a discrete primordial cloud – or reveal whether an apparent member of that galaxy cluster was in fact from elsewhere and in close proximity merely by chance. {The poster formerly known as 87.81.230.195} 84.21.143.150 (talk) 18:19, 7 January 2013 (UTC)
January 7
Choke holds
Resolved
In reference to the premise behind the manner in which choke holds are effective, I find it difficult to understand how a chokehold such as the rear naked choke can "immediately deprive the brain of oxygen" ("safe application" section) if the vertebral arteries continue to supply blood to the Circle of Willis. I can hear that there's not enough blood flow, and so perhaps there's not enough oxygen for the victim of the choke hold to continue normal function, but to say that the brain is "immediately deprived of oxygen" suggests that there is no oxygen supply. DRosenbach06:13, 7 January 2013 (UTC)
According to my Chambers Dictionary (1979), the meaning of "deprived" is as follows: to dispossess; to keep out of enjoyment; to remove (as in remove from office). According to http://www.thefreedictionary.com/depriveit means to prevent from possessing or enjoying; to keep from possessing or enjoying; to remove from rank or office. It seems that DRosenbach is correct and StuRat is wrong (again). Wickwack 120.145.140.205 (talk) 07:09, 7 January 2013 (UTC)
That definition doesn't say to "TOTALLY prevent from possessing or enjoying", you just made that part up. See relative deprivation. You can't have a relative amount of an absolute, that makes no sense: "To relatively TOTALLY prevent from possessing or enjoying". A common phrase is a "deprived childhood", which means they had fewer material goods as a child, not none (they would have died in short order without any food, for example). Another common use is in the phrase sleep deprivation, which just means not enough sleep, not no sleep. Here's another example: "Excessive homework deprives children of time with their families" . Obviously, this doesn't mean they don't see their families at all. And sensory deprivation, as our article states, includes a "reduction" in stimuli. Here are synonyms for "abridge" (meaning to reduce) which includes "deprive of": .
So, once again, Wickwack, in a blind attempt to attack me, you didn't bother checking your facts and sources first, made me waste my time to prove your wrong, and the time of everyone else who reads your incorrect comments. StuRat (talk) 07:36, 7 January 2013 (UTC)
I agree with StuRat on the 'deprivation' thing. However it seems to me all of these are somewhat approaching this from the wrong way anyway. We're talking about medical usage. If you check out Cerebral hypoxia and Hypoxia (medical), it's clear being deprived of oxygen doesn't mean completely deprived. If you don't like wikipedia, you could easily find other sources with the same usage. As the first article attest, particularly when it comes to the brain being deprived of oxygen even if it's only temporary and incomplete can have fairly bad effects. Nil Einne (talk) 09:04, 7 January 2013 (UTC)
.
Here again we see StuRat come back when he has been refuted - he can't accept being disagreed with and can get quite ridiculous and silly. Silly because he tries to defend what was initially just a simple human mistake. If his time has been wasted then that is his choice alone - I neither requested nor forced a response from him. His comment about me not bothering to check my facts is bizare considering that I directly quoted from a highly regarded dictionary (Chambers) and backed it up with an online link. I also checked some other dictionaries but did not mention them as there was no difference.
I cannot see why StuRat linked to the relative deprivation article (Relative deprivation is the experience of being deprived of something to which one believes oneself to be entitled) as this is both a technical term and a completely different concept - "relative" used in the context of relating to reality. — Preceding unsigned comment added by 124.182.3.218 (talk) 11:52, 7 January 2013 (UTC)
However, as it is known that Misplaced Pages is read by folk whose first language is not English, I feel it is worth while to show why DRosenbach is correct and StuRat is wrong. Here's the relavent principles:-
1. As I said before, the dictionary meaning is dispossess, remove, keep out/from, and the like. These are all or nothing words.
2. DRosenbach is correct in that blood flow in the circumstances of the article is not completely cut off, therefore the word "deprive" has been used incorrectly. It was used incorrectly as because of it a reader can validly (under the rules of English) take it to mean total cutoff of oxygen, just as DRosenbach said. Even if you accept that partial cuttof is a valid interpretation, it is still not good English as then there are two interpretations when there should be only one.
3. Expressions like "Excessive homework deprives children of time with their families" is not particularly good English, but is a use different to the use DRosenbach cited and never the less is valid because time is not a singlular non-divisble object. A portion of the child's family time has been taken away, not all the family time and this is clearly what is meant. In contrast, the expression "immediately deprive the brain of oxygen" is validly understood to be total loss of oxygen.
Let's say you have a 3 x 45 mm steel nail. I can either take it from you wholely, or leave you with it in its' entirety. I cannot, not without cutting tools anyway, merely reduce your possession of this nail. It is appropriate to write "Wickwack deprived StuRat of his nail" and it means Stu lost his nail completely.
Let's say I reduce the water pressure to Stu's house. It is NOT valid to say "I have deprived StuRat of water" - he still has water. We could say, if Stu then has problems resulting from the low pressure, "Wickwack has deprived StuRat of his enjoyment of water", or (better) "Wickwack has deprived StuRat of full water pressure." See the difference?
It is quite valid to write "It deprives the brain of adequate oxygen" (which is how the articles cited by Nil Einne start off), but not valid to write "It deprives the brain of oxygen", unless the brain is totally cut off from oxygen. See the difference?
4. The word "deprived" may get some common use in a partial effect context, as do many expressions in common informal and spoken use. But in things like encyclopedias, wikipedia articles, scientific papers, etc, the correct dictionary meanings should be used. Otherwise, readers may be confused, as the non-verbal clues in human communication are not available. For example teenagers these days say "Cool" to mean "That's good", "I like it", "Thank you" and similar. In earlier days teenagers used the word "gas" in a similar way (as in "It's a gas!"). Both, in theory, are a misuse as neither word means "good". However, they have become common use, so it's ok to use in speech and informal writing. But not in formal writing.
Actually it seems clear from the articles I cited the meaning is unclear whatever you say the dictionary says. Hence why for clarity both articles always make it clear whether or not they are talking about complete or total deprivation of oxygen rather then just assuming people will follow the definition used in some dictionaries and complicated technical arguments about what the word should mean in the context. Nil Einne (talk) 13:02, 7 January 2013 (UTC)
Purely original research, but I used to do a bit of Judo and have been on the wrong end of this hold a couple of times. My memory is that you are still able to breathe, but after a few seconds a large black patch appears in your vision and you realise that it's time to tap for a submission before loss of conciousness becomes an issue. I'll leave you to argue over the wording. Alansplodge (talk) 13:13, 7 January 2013 (UTC)
From what I understand of the various articles on choking, there are two main types of choking described:
Blood choking
Air choking
The choking I was referring to, such as the rear naked choke, is described as a blood choke, in that the vessels supplying the brain with oxygenated blood are actively blocked by the position of the attacker's upper and lower arm, while the trachea is left patent within the crook (inner concavity of the elbow) of the attacker's arm. The point being, I believe, that the trachea remains unharmed (if it were crushed in the hold, permanent damage would ensue) and the victim is able to breathe normally -- the unconsciousness occurs not because the victim ceases to take oxygen into his or her lungs, but because the oxygen that diffuses into the victim's blood in the lungs is not able to get to the brain. DRosenbach01:47, 8 January 2013 (UTC)
Quite so. However, blood flow to/from the brain is not cut off completely. If it were, it would be the same as cardiac arrest - unconsciousness would occur within 2 seconds or less. See also Wnt's comment below. It's not just a matter of obstructing the flow though. The sensors for blood pressure are in the neck arteries - applying external pressure tricks the brain into thinking blood pressure is way too high and it instructs the heart via the parasympathetic system (vagus nerve) to bring it down. It's the commanded drop in pressure that causes blackening vision and fainting as much as the obstruction, though the pressure drop in the brain is not as great as it is in the body. See http://www.cliffsnotes.com/study_guide/Control-of-Blood-Pressure.topicArticleId-277792,articleId-277694.html Wickwack 124.182.165.212 (talk) 03:53, 8 January 2013 (UTC)
I am not a registered editor and in conformance with Misplaced Pages policy I do not edit articles. If DRosenbach (the OP) is not happy with the wording in the article he cited, he is free to ammend it to make it clear only a partial effect is meant. Clearly all except Stu would be happy if DRosenbach does so. However, Stu just likes to argue, but apart from that he's pretty smart and at the end of the day I suspect he would support clarifying it too. Over to you, Mr Rosenbach. Wickwack 124.182.3.218 (talk) 14:06, 7 January 2013 (UTC)
I note that circle of Willis explains that the anatomy is variable, so I wonder if some people may be more resistant to the maneuver than others based on the capacity of their brain vasculature to reroute blood flow...
The idea of 'totally' depriving the brain of oxygen is physically absurd - degassing a solution requires considerable effort and is never truly absolute. The issue is only whether the oxygen level is sufficient. It would seem unnecessary to say "partially" deprive, but if the point is otherwise confusing to the readers, then that is what matters. Wnt (talk) 15:47, 7 January 2013 (UTC)
Clearly the phrase "immediately deprive the brain of oxygen" could be interpreted by one person (such as me the first time I read it) as "totally deprive" and by another person as "at least partially deprive". So why don't we just put in another wording that no one will misinterpret? I'm going to put in "immediately reduce the supply of oxygen to the brain".
(Spin-off question - separated from previous answers)
Over time atleast about 20 or so people have specifically requested that I register and take on the job of cleaning up certain Misplaced Pages articles that are in bad shape. Nearly as many have just requested that I register as an editor just to continue contributions to Ref Desk. Usually when this happens I provide an explanation on their talk page or on the Ref Desk talk page on why I'm not registered and why I do not edit articles. On occaison this has triggered spirited debate between various editors and admin folk, which is not a desired outcome. A search of archives will reveal that while you can edit articles without registering (which is one reason why I don't), most of the regular Misplaced Pages community do not like it, and it is against policy. A couple of years ago, after a spate of vandalism, unregistered editors were supposed to be prevented from editing articles, but never the less they still can, which I demostrated once by correcting a single word in one article. Incidentally, the reason why I do not edit articles is 1) because it is just too darn easy for work done with care to be undone by some peanut who hasn't done his homework, 2) certain admins have mistaken me for someone else and decided I should be blocked; 3) some articles are so bad it would take weeks of solid work to put them right. If anyone wants to know more about these articles or my reasons, invite me to your talk page. Misplaced Pages is an extremely valuable resource - it is a great pity that articles are subject to illinformed change and outright vandalism. Wickwack 121.221.229.133 (talk) 00:36, 8 January 2013 (UTC)
Sure, people will request that you create an account. I'll request it too! It's a good idea. But it's NOT a requirement...there are only around 4,000 articles (out of 4.1 million!) that you can't edit without an account. (See WP:SEMI for the rule and Special:ProtectedPages for a list of all protected pages). But you can edit 99.9% of articles without registering. Wikipedians tend to treat "IP editors" (those who edit without registering) with deep suspicion...that's unfortunate for you - but not without good reason. Almost all vandalism comes from IP editors and almost all IP editors (numerically) are vandals. So it becomes a knee-jerk reaction to suspect any IP editor of evil-doing. That's a bad reaction because there are without doubt a large number (albeit a small percentage) of excellent IP editors. But it is categorically not against policy to edit without registering. If it was, we could flip a switch in a configuration file and ban all editing by IP users in a heartbeat (I do that on all MediaWiki sites that I personally run). Your reasons for not editing articles are well-understood...but how can you demand that absolutely any idiot (specifically: any school kid with access to a school computer who should be doing a history class but is actually typing obscenities into the article about Barack Obama) be allowed to edit any article - and in the same breath demand that edits that you make should be sacrosanct and that nobody should ever change the golden words you've created? Don't you see that those are contradictory demands? Then you complain that people have "mistaken you for someone else" - well, duh! If your only identification is your computer's IP address and that address is given to you by your Internet Service Provider (using DHCP) - then the person with the address "121.221.229.133" is you today - and some horrible vandal tomorrow - and you again next week. It's inevitable that you'll be accused of all sorts of things that you didn't do. That's why creating an account here is a good idea. It's password protected, so the only person who can use it is you. Other editor's dealings with you will be consistent and your reputation will stand over long term. When people see User:SteveBaker - they see that I've been an editor for 7 years and made 25,000 edits and never once been blocked, banned or sanctioned. When they see User:121.221.229.133 - they know nothing about you and since people using that same "name" have been evildoers - it's just inevitable that you're going to occasionally be accused of doing evil. SteveBaker (talk) 14:42, 8 January 2013 (UTC)
I have made NO contradictory demands. You are confusing Misplaced Pages articles with Ref Desk. You are also confusing altering text in Misplaced Pages articles with posting new comments on Ref Desk, leaving other posts as they are. I have never altered the text posted by someone else. I monitored the Admin Noticeboard and talk page for a while - it is quite clear that there are good admins and bad admins, and quite clear that folk get blocked who darn well should get blocked, and folk who get blocked because admins take a sloppy approach or maybe just don't like something rattling their cage. I think allowing unregistered folk to edit Misplaced Pages articles is stupid. I think allowing people to post questions on Ref Desk without registering is ok - there's no conflict, they are two different environments with different purposes.
Yes, "deprive" can mean either "totally deprive" or "partially deprive". In the case of oxygen deprivation it obviously means "partially deprive", no matter what Wickwack claims, but clarifying the article is a good idea, to avoid confusing people like him. StuRat (talk) 21:01, 7 January 2013 (UTC)
Wickwack, can you point to this supposed "policy" about unregistered users not editing articles? As far as I know, there is no such policy. Unregistered editors are encouraged to register, but the system recognises that many people do not want to, for any number of reasons. You are still just as welcome to edit articles as I am, and you are subject to the same rules and standards of general conduct as everyone else. What registered editors may feel about your state of unregistration is none of your business, and you should not let it prevent you from editing articles. -- Jack of Oz05:25, 8 January 2013 (UTC)
There is absolutely no policy forbidding IP's from editing articles; where Wick got this impression is well beyond me given A) how ubiquitous this type of editing is (I doubt more than one tenth of one percent of articles on the whole of the English Misplaced Pages has not had contributions from unregistered editors, most of them constructive and welcome) B) the massive amount of community discussion that went into forming the consensus that this was best all around for the project, a stance which has since remained the standard, with little serious challenge, since the earliest days of Misplaced Pages, and C)every major policy page concerning itself with the registration process and beginning editors makes it clear that, while there are significant advantages to registering (both for the editor and the project as whole), it is by no means required and anyone who can improve any article is encouraged to, even if they can't/won't register. I forget where in the Wikimedia framework reports on the exact figures are published (though I know the Signpost occasionally reports on them), but it seems almost a certainty that about half of all edits on this particular Misplaced Pages are made by unregistered users and mostly always been that way. Hopefully Wick can show us where he was misinformed on this matter, because if there's even so much as an essay suggesting a contrary consensus, it should be altered.
On a separate note, the degree of discussion above on a minor semantic point is asinine, bloated by petty conflict and not really doing much to assist the OP. For the record, my use of the word deprivation (and that of virtually everyone, I think) is without a doubt one that scales to context and does not necessarily mean absolute absence of the resource being withheld; I've never seen a formal definition in conflict with this in any dictionary, and I can't even begin to imagine how many times I've heard it used in my life, from countless individuals, in ways that are inconsistent with Wickwack's all-or-nothing interpretation. In it's common clinical uses, it's clear that it can refer to a partial absence.
Now, addressing the OP's question (and indeed the above absolutist debate on the definition of a single word is especially absurd given he refined the question for us further), yes, you are correct Rosenbach: "immediately deprives" is indeed an overstatement of the facts. As has been noted above, by Wick and others, a certain amount of oxygen will remain in the brain and, regardless of the hold, a certain amount will probably continue to flow into it; if the hold is successful in rendering the individual it is applied to unconscious, it is either the result of a certain threshold of oxygen supply not being met or, more likely, that the chemo- and baroreceptors involved have simply been manipulated to trigger this reaction. Indeed, the victim of the hold should hope for the latter since it doesn't take long for the brain to be deprived of oxygen (even in the sense of partial but significant deprivation) before there is significant risk of permanent injury. Snow (talk) 06:49, 8 January 2013 (UTC)
As for where I was supposedly "misinformed" - Ref Desk talk page. As I said above, if anybody wants to follow up what's wrong with certain articles, or my reasons for not registering or editing articles, they are welcome to invite me to a discussion on their talk page or admin talk page. This is not a discussion that should be here on Ref Desk. In fact this whole question, from the OP onward, should have been on the article talk page, not on Ref Desk. However, the OP did ask, he got the usual off the cuff unsupported crap from StuRat, which in this case was incorrect, and so I posted a correction and subsequent explanation in good faith. DuoDuoDuo corrected the article, so we have a good outcome. On this page, that should be the end of it - no further debate can be of any value to Ref Desk users at large. Wickwack 124.182.165.212 (talk) 07:16, 8 January 2013 (UTC)
I posted many references which prove that "deprived" can mean "partially deprived". It is you who made the absurd statement that it always means "totally deprived", with no references which back up that claim. StuRat (talk) 07:29, 8 January 2013 (UTC)
There's really no "supposed" about it - you were misinformed; Misplaced Pages policy not only allows for IP edits, it encourages them in cases where registration is not possible or undesirable to the editor (assuming it is not a case of sockpuppetry or other abuses). I'm not really interested in your motivation for not registering or not or editing or not as that's entirely your business and of no relevance here. But you're right as to the appropriate placement of this discussion in the first place; it probably would have been better served by taking place on the talk page from the start, though I understand the OP's motivation in coming here to establish a technical definition of the terminology involved. And yes, Stu sometimes bites off more than he can chew with highly speculative responses here, but in this case I happen to think he was entirely correct and helping the OP. I'm equally certain your initial comments were in good faith (though things would probably have been better off without that antagonistic jab at Stu in your very first response). However, you both clearly quickly let your stances and your responses become personal, resulting in the acrimony and bloat above. But let's allow it to rest here as it seems we've all come as close to consensus as we will on this topic and the OP is presumably satisfied. Though I'd like to make one quick side-note here and request that you not format other editor's posts on this page (at least not in-so-far as such tools as </small> tags go); it's inappropriate to make that decision for another editor. Snow (talk) 07:43, 8 January 2013 (UTC)
(Argh! This discussion really doesn't belong here - it's WAY off-topic - but corrections of fact need to be made).
Wickwack is somewhat correct - there are articles that (s)he cannot edit without registering an account and logging in to use it. Snow is also correct in that a guiding Misplaced Pages policy is that people should be able to edit articles without registering. The trouble is that widespread abuse of that policy means that we simply can't cope with every single part of Misplaced Pages being editable by IP editors. Hence, WP:SEMI says that some small number of "semi-protected" articles (those with a silver padlock in the top-right corner) can only be edited by registered users with at least four days service and ten prior edits.
So Wickwack truly cannot edit semi-protected articles such as Homosexuality, Computer or Misplaced Pages. That said, almost all semi-protected pages are templates, redirects or user pages. A few of them are articles that are being protected for the short term (days to weeks) against a short-term assault of IP vandalism (generally articles that are especially news-worthy and things that are currently on the front page). Generally, the only long-term semi-protected articles are about highly controversial or frequently-searched-by-annoying-schoolkids-from-school-computers topics (hence the three examples above). In one such article that I worked on for a while (Computer), we were getting vandalized to the tune of 40 edits per day by various "IP users" (people not using registered accounts) and over the course of an entire month that I searched, we didn't get one single good edit from an IP user. Over the same span, there was just one bad edit from a registered user and 30 or so good edits from registered users. The regular editors of that page became so overwhelmed by the effort in keeping the article readable that permanent semi-protection was deemed to be the only way to keep the article usable. Once in a while, some well-meaning admin will come along and remove the semi-protection from Computer and we're once again overwhelmed until we can persuade another admin to step in and turn it back on again.
This is unfortunate for people like Wickwack who edit in good faith from IP accounts - but in the face of such overwhelming abuse from IP editors - we really have no choice but to shut out the very, very few good guys in order to keep out the overwhelming amount of crap from the bad guys.
I don't understand why frequent good-faith editors who do good work and sign their posts with a 'handle' like Wickwack does wouldn't preserve their anonymity by creating an account (publishing your computer's IP address every time you post is very non-anonymous - I could almost certainly find Wickwack's real name and location from his/her IP address in under 20 minutes - but figuring out that information from a Misplaced Pages account name would be near impossible). But choosing not to create an account is something enshrined in Misplaced Pages principles that is unlikely to change. (IMHO, we should require registration for all article-space editing...but that's just me!).
As far as I know, none of the reference desks, or their talk pages are, or have ever been, semi-protected. It would be ridiculous if they were because almost all of our questions come from IP users. SteveBaker (talk) 14:05, 8 January 2013 (UTC)
This really doesn't belong here on this page, but why don't I register? Simple - as I said before, certain admins think I am someone else (which was very clear from their discusion on the admin talk page) and have invested a lot of time and effort to block me. If I registered, that would make it easy for them. As for privacy, you can use an IP locator - that will locate me to Australia immediately. Big deal, there's only 25 million of us. And each time I access the internet, I get a different IP anyway, allocated from a national pool. You will be able to discover the internet providor. Big deal, they only have about 4 million customers. If I registered, then admins do know who I am, and if it is hackable, so do villains. Having said that, I think allowing non-registered folk to edit Misplaced Pages articles is stupid. See post on your other comments above. Wickwack 58.169.236.195 (talk) 15:05, 8 January 2013 (UTC)
But if you used a registered account then nobody could mistake you for anyone else and this mess would never have happened. In fact, if you registered now (preferably with a handle other than Wickwack), nobody would be aware of any of this past confusion and you'd be able to edit as you with whatever respect you deserve from the quality of your posts. As for locating you, unless your computer has the security of Fort Knox, anyone with the right set of black-hat hacking tools will be able to reach the computer that you're using right now via it's IP address, prod it until they gain entry to it and from there all bets are off. If you use a registered account then the only way to connect you to a specific computer is via the "checkuser" extension which is only used rarely, by a few individuals (just 43 of them at last count) - and after considerable oversight. There are very few places where your IP address is made public like it is if you edit Misplaced Pages without an account...there is a good reason for that! SteveBaker (talk) 17:17, 8 January 2013 (UTC)
Maybe. My experience is that there was someone that the admins didn't like. He tended to post a lot of comments of Ref Desk, but not anything that would justify blocking. He also participated in article talk page discussions - which I've never done. Judging from the admin page discussion, they think that each time they blocked, he re-registered with different data to get around it. Then when I popped up and posted on Ref Desk they blocked me. Sometimes they block an IP address, cutting me off - that's completely stupid, as the IP address changes from one session to the next. It might be in this case sometimes it wasn't me they were aiming at - that's what they said when I complained once. Wickwack 124.178.62.219 (talk) 02:05, 9 January 2013 (UTC)
Again, your defense in the event that you happen to get handed the same DHCP IP address as some blocked Misplaced Pages vandal is to simply register an account. Problem 100% solved! SteveBaker (talk) 04:06, 9 January 2013 (UTC)
If the IP address is blocked, it's blocked, whether the temporary user of that address is registered or not. Either way, shut down one's internet session and start another - problem solved. My point was - admins sometimes do dumb things. And if they block a registered user, he can't use his registered identity regardless of his current IP address - but he can just go ahead and continue, either by re-registering or operating as an unregistered user. So if one can't post on Ref Desk, one doesn't really care why, just restart unregistered and it will work. Can you not see that? Wickwack 121.215.21.138 (talk) 04:35, 9 January 2013 (UTC)
Blocking an IP does not necessarily block registered users who happen to have that IP. Blocking an account sometimes also automatically block various IPs that that account uses. But the ref-desk is decidedly not the place to continue this discussion. The technical aspects are well-documented, and the philosophical and pro/con debate wore out its welcome years ago. DMacks (talk) 04:50, 9 January 2013 (UTC)
I am slightly disappointed, and surprised, to hear that IP editors are treated with 'deep suspicion'. Until registering about 14 months ago I was a long-term IP editor (about 26 months, just over 11,900 edits). My experience as an IP was 99.9% positive in interacting with other editors. Very rarely did I get 'nasty' messages. (The only one I remember was from another IP editor!) What really makes me suspicious is a new account with a name like "Suckmypen15123" or "Phuckinstick", both are real accounts!
I suppose I was fortunate to have a static IP for that entire period, also my first edit was undoing some vandalism (and I used an edit summary too!) I see what new editors (IP or not) get up to, and spend time reverting (and helping) them, when necessary. But they also do a lot of good edits. I think often they are newbies making their first edits and simply not sure what is the right thing to do, hence often in good faith putting un-sourced (but correct) information onto pages (As I see I did too, 40 months ago). I recently reverted an un-sourced IP edit to a towns population figure, which I soon found was exactly correct. I just had to source it correctly, The IP tried, but obviously didn't know the exact way to do it. - 220of17:33, 9 January 2013 (UTC)
Bug identification
Can someone please identify this bug for me? WARNING: GROSS, click at your own risk:. I'm in the Laurentian Great Lakes region. I found the bug indoors. Dncsky (talk) 09:03, 7 January 2013 (UTC)
I bought a replacement synchronous motor for a microwave oven. The label shows TYJ50, AC 220-240V, 50/60Hz, <4W, 33r/min but no manufacturer. It is cylindrical, of diameter about 50mm and length about 15mm, and was a cheap online purchase. Before going to the trouble of installing it I tested it and though it runs at near enough the rated speed, the case gets too hot to touch after 5 minutes unloaded. Is that to be expected with this kind of motor? — Preceding unsigned comment added by Semiable (talk • contribs) 14:35, 7 January 2013 (UTC)
It seems unlikely that the motor is expected to get that hot in service - but perhaps it's supposed to be bolted to the metal frame of the oven - and that conducts the heat away and radiates it over a larger area to act as a heat sink. It's hard to tell. SteveBaker (talk) 20:31, 7 January 2013 (UTC)
Are there any creatures in existance that sport an odd (even just one) set of appendages? Suppose a "half" creature with just one brain lobe, one eye, one leg, etc. Or say a tri-lateral layout. Have any of these been observed, especially in the case of a single-sided organism?
75.220.96.17 (talk) 15:02, 7 January 2013 (UTC)
Starfish have five-fold radial symmetry. They really don't have a single brain, but instead a ring of neural material that goes around the central hub. A starfish can be cut up (with a cut taking a whole limb and the associated central segment) and that single limb is a viable independent creature which will eventually regenerate back into a 5-fold starfish again. -- Finlay McWalterჷTalk15:07, 7 January 2013 (UTC)
Adult flatfish are one-sided (example), having two eyes on either the left or the right side of their body. However they acquire this asymmetry during their youth, as they are hatched symmetrically. There are also the extinct Trilobozoa with tri-radial symmetry. - Lindert (talk) 15:17, 7 January 2013 (UTC)
Male Fiddler crabs are asymmetric. (A wierd thing about these crabs is that if they should happen to lose their giant claw, the claw on the opposite side will rapidly grow to enormous size to compensate - and the missing claw will regenerate as a tiny claw.) But I suspect that symmetry is so common because it results in a huge saving in the amount of DNA an animal needs. SteveBaker (talk) 15:33, 7 January 2013 (UTC)
The majority of animals are bilateria, including even starfish (which basically start to bend right when they become teenagers, until they they have bend once around and lost the left half of their body). Some animals loose some of the symmetry during later developments. Animals which have no symmetry are e.g. sponges. And WHAAE, in this case Symmetry in biology. --Stephan Schulz (talk) 15:45, 7 January 2013 (UTC)
Of course, despite being called bilateral symmetric, (and this is sorely ignored in our article), no mammal is actually symmetric, and in fact imposing left-right asymmetry through Nodal is crucial in early embryogenesis. Fgf10 (talk) 19:28, 7 January 2013 (UTC)
Indeed. See also situs inversus, etc. Thinking about it, I would suppose one could almost come up with a sort of biological theorem here, though - we tend to think of animals as bilaterally symmetrical because they start off with a mirror plane and then adjust development afterward. The ultimate reason is that in order to have a plan of development, you have to define one axis (radial symmetry), then another - bilateral symmetry - but only with three separate axes defined do you break from that plan. So in order for an animal not to be bilateral symmetric at the beginning it would need to define all three axes, and do so immediately, and what is the selective pressure for that? Either that or, like sponges and plants, just not have much of a plan. Wnt (talk) 21:42, 7 January 2013 (UTC)
Very good point, and I can't imagine a workable system where asymmetry isn't generated through a 'disruption' of initial symmetry. You'd have to have very well specified polarised cell divisions from division 1 onwards, I guess. Fgf10 (talk) 22:07, 7 January 2013 (UTC)
Nobody is arguing that there isn't asymmetry in detail (your heart, liver, pancreas are all highly asymmetric). But please re-read the OP's question. We're being asked about animals with gross asymmetry - like having one arm on one side of the body and two on the other (like the fictional "Moties" in The Mote in God's Eye). I'm having a hard time coming up with real-world creatures like that (although the fiddler crab and adult flatfish are close). Nature loves symmetry - because it's efficient...but it's not perfect symmetry. Humans have two, symmetrically-placed, kidneys - which is great - if you lose one, you can still live out a fairly normal life with the other. However, we have only one (highly asymmetric) heart and one liver - and if you lose either, it's curtains for you. When you only have one of some organ, placing it symmetrically is difficult - there just isn't room on the center-line of the body to place everything in the middle.
Evolution is all about optimizing efficiency. Having most things be symmetrical saves on genetic information to code the two halves of our bodies separately. But slavish attention to symmetry is inefficient in other ways - hence only having one liver and one pancreas and putting them on opposite sides of the abdomen is more efficient than having just one of each on the centerline or duplicating functions by having two of each, symmetrically placed like the kidneys.
Left/Right-handedness is a similar deal. We have a symmetrical brain - but there isn't enough computing capacity in it to duplicate functions and have things like manual dexterity or eye dominance in both halves - so we break symmetry to save space - and as a result, we have one hand that's more useful than the other and mathematical functions present in just one side of our heads.
Evolution probably took some complicated path to get to this situation - yet it's still a little surprising that strongly asymmetric exterior forms are so incredibly rare in nature.
Very good points. Yes, gross symmetry is efficient, but generating asymmetric localisation does not require extensive genetic differences in both halves, so is not a big efficiency loss. Asymmetric expression of certain key signalling molecules, Nodal and Lefty (yes, the gene is actually called lefty) is enough to promote asymmetry. I'd be surprised if this isn't the mechanism that forms the one large claw of a Fiddler crab, but I couldn't find the exact mechanism in a quick search. I couldn't see making even something like Moties as being impossible in this way. Maybe in the case of a Fiddler crab having one big claw is sufficient, so it's actually more efficient to develop it asymmetrically and not waste energy on growing a second? Fgf10 (talk) 15:54, 8 January 2013 (UTC)
As I pointed out before, the weird thing about the fiddler crab is what happens if the large claw gets amputated. In this case, the OTHER claw grows huge and the missing claw regenerates with a small pincer...what you end up with is a mirror-image of the original crab. It's tough to explain this with the Lefty gene. SteveBaker (talk) 16:53, 8 January 2013 (UTC)
Sounds like a standard case of positive feedback: a big claw keeps the other claw small, a small or missing claw makes the other claw big. Genetics tend to act more like a recipe than a blueprint; a single change often has multiple effects. --Guy Macon (talk) 19:15, 8 January 2013 (UTC)
Just nitpicking: The human kidneys aren't symmetrically placed: The right kidney is placed a bit lower than the left kidney.
The narwhale is an example of asymmetry trying to pass for symmetry. The "horn" is normally the left tusk, but is close enough to the center that it's not obviously asymmetrical, unless you look closely. StuRat (talk) 20:48, 8 January 2013 (UTC)
Is it true that the more human hair is smooth\straight, the more it is likely to dropout?
In other words, can we generalize that populations that generally have UNsmooth hair, Like Non-asian Males in general, some African peoples, Yemeni Arabs, and Australian !!! Aboriginals, will tend to have LESS natural hair dropping?
what are the proteins \ chemicals that exists in straight hair, that contribute much to the odd of it's dropping?
I'm wondering if you might need to narrow down "Aboriginals" a bit. We all have ancestors who were "aboriginal" to somewhere once. I will agree, based on purely original research among lots of examples of friends my age (60+), that baldness is (almost?) non-existent among Australian Aboriginal men. I'm quite jealous. HiLo48 (talk) 22:19, 7 January 2013 (UTC)
Note that Baldness and hair dropping are not the same.
I remember reading decades ago that the fairer one's hair, the thinner the hair, and the more likely baldness is, with the exception of red hair, which is the thickest and whose bearers are least likely to go bald. From what I remember I wouldn't call the book a reliable source, though, and a quick google search only gave info on either hairloss and hair dyes or what color bald men have on their driver's licenses. μηδείς (talk) 02:59, 8 January 2013 (UTC)
Quantum fuse
There's a fallacy in quantum physics that I've been thinking of, but I
haven't found the proper name for it yet. As a placeholder I'm calling
it the quantum fuse, because it acts like a fuse you light for say a
bomb.
Take a very pure block of some semiconductor, silicon will do, and
carefully dope it so it has a long line of holes in it, each of which
can comfortably hold one electron. Above all but the last hole is an
electronic circuit that will insert one electron into each of these
hole, all at exactly the same time. I.e. the first through the next to
last hole will be filled faster than a vacuum photon could cross that
distance. At the first hole there is an additional electron ejector
that can be set to fire at the exact same moment as all the rest. And
at the last hole there is a sensor that will read out if it has been
filled or not.
For a logical zero the additional ejector does not fire in that extra
electron, and so every hole except the last one will be filled at the
same moment and the last hole will read zero.
For a logical one the additional ejector does fire. The first hole
gets two electrons, but can only hold one so one of these tunnels over
to the second hole. Since any tunneling event is instantaneous, the
excess electron arrives in the second hole at the same moment an
electron is added to fill that hole. And so one of the electrons is
bumped over to the third hole and so on. Ergo the final hole in the
series gets filled before any signal could have arrived from the
additional ejector.
Your fallacy is that you depend on a fictional, hypothetical "electron injector" whose mechanism (which you did not explain) is inconsistent with any actual device you could actually build. Your entire thought-experiment depends on the guarantee that your electron-injector will put an electron into the circuit. Yet, you did not explain how and so you didn't consider the scenario that the injected electron doesn't go where you want it to. Diffusion of electrons depends on the state of the semiconductor; adding electrons will saturate the charge carriers. This reduces the current; or, quantum-mechanically, reduces the probability that an individual charge-carrier will actually move. But, this need not even be treated quantum-mechanically: we use the saturation model to estimate properties of devices without ever considering quantum effects. If you want to solve analytically at the atomic level, you will get even more accurate results because you'll derive diffusion coefficients for every single constituent charge-carrier. Nimur (talk) 16:29, 7 January 2013 (UTC)
Tunneling isn't instantaneous. It can appear to be faster than light, even in classical electrodynamics (where you can get tunneling of light between fiber-optic cables, for example), but what you're actually seeing is (I think) a quadratically extrapolated signal, analogous to the familiar fact that the electric field of a moving particle appears to come from a quadratically extrapolated "current location". Also, the exclusion principle isn't absolute—it's just the lowest-energy states that are filled, and there is always room for more electrons if you supply enough energy. So I think your fuse, if it works, will work by means of an ordinary pressure wave, like Newton's cradle. -- BenRG (talk) 17:06, 7 January 2013 (UTC)
This is an intriguing question - I haven't answered it myself, but I can point out a few things. First, we have articles quantum tunneling, faster-than-light, and Raymond Chiao which express the root observation that tunneling is "1.5 to 1.7 times" faster than light. But the Chiao article expresses some doubt about it, and I haven't determined the current thinking on the point. I think that if it is true then there should be many other ways to get to the same end of making the effect macroscopic - for example, I think you might have what begins as a single photon pass through a long series of tunneling barriers, while being in a lasing medium to increase its intensity (to make up for reflection losses in tunneling). Wnt (talk) 18:21, 7 January 2013 (UTC)
Quantum tunneling is the same as tunneling in classical relativistic wave theory. The "tunneling" case is the case better known as "total internal reflection", where Snell's law implies that the wave number perpendicular to an interface must be imaginary on one side. This leads to exponential decay instead of oscillation in the perpendicular direction (e instead of e), while the wave still oscillates in the parallel direction and in time (as required by the boundary conditions). This looks like the lower image on the right, where the medium on the left has a higher refractive index (the image is missing the internally reflected wave, though). If you put another medium of higher refractive index on the right, some of the wave will leak into it as an ordinary propagating wave (attenuated by an amount exponential in the width of the center region). The fact that the wave crests are horizontal instead of diagonal in the center region is what leads to the notion of "instantaneous propagation": it looks as though the phase of the wave simply skips over the central region regardless of its width. However it's a theorem of classical relativistic wave theory that you can't send a signal faster than light. In the quantum case everything is exactly the same mathematically, and so the natural conclusion is the same, but people tend to get all woo-woo as soon as you attach the name "quantum" to something.
A similar argument was once invoked to prove that the speed of gravity must be much larger than c: if the Sun's influence on the Earth lagged by 8 minutes, the Earth would be pulled toward the location of the Sun 8 minutes earlier, which would add a backward drag component to the total force, which would have long since led to the Earth spiraling into the Sun. But it doesn't work that way in relativistic field theory: although the force depends only on the Sun's position 8 minutes earlier, it is actually directed toward an "extrapolated current location" of the Sun. Likewise, a tunneling wave emerges with an "extrapolated future" shape. As long as the tunneling time is small compared to the effective time resolution of the wave, the extrapolated wave will be indistinguishable from the real thing.
I've always experienced basements to remain at a comfortable temperature, but now I live in a house where it's nearly as hot/cold as outdoors. Why?
All my life I've loved the basement - it's the coolest place to be in the summer and in the winter it's comfortable as well. A few months ago I moved in to a house that has a basement that seems to perpetually be just a little bit warmer than the outside temperature - in summer it's miserable, and in the winter I can almost see my breath (I live in Minnesota). How is this one different from literally every other basement I've been in for my entire life? I thought it was just as simple as being below ground. NIRVANA2764 (talk) 16:23, 7 January 2013 (UTC)
I suppose we could look up heat conductivity of various kinds of soil, but first, can you assure us that the basement is actually well enclosed from the outside air? (For example, you could look at the circulation of smoke) Wnt (talk) 18:01, 7 January 2013 (UTC)
Agreed. It's probably drafty windows. Another factor is how much heating or A/C your basement gets. Some forced air systems leak air all over the place, down there, while others are pretty tight. StuRat (talk) 20:46, 7 January 2013 (UTC)
Does paper really dull scissors faster than cloth does?
For many years I have noted with amusement the following quirk of human nature:
Many engineers and technicians who do fine work with paper swear that cutting cloth will ruin their scissors. I saw one worker who trimmed filter paper for an aerospace application putting a padlock though the scissor handles when not in use.
Meanwhile, many people who do sewing swear that cutting paper will ruin their scissors. I have seen claims from both groups that one snip of the wrong material means you have to buy new scissors. I wouldn't be surprised if MDs made the same claim about surgical scissors.
I searched for anyone who had done actual testing. Didn't find anything but I did find this. I am thinking of emailing them if nobody here has an answer.
It's kinda-sorta possible for both statements to be true. I doubt they are - but let's play devil's advocate for a moment. Scissors are held together with a screw or rivet - when the scissors are badly worn, this opens up, gets loose and makes a bit of a gap between the blades - which makes them cut less effectively. Suppose (for the sake of argument) that cloth is thicker than paper and cutting it tends to bend/wear the rivet more quickly than paper...and let's suppose that phytolith (or whatever) in paper physically dulls the blades by wearing them out in ways that cutting cloth does not. It's then possible that cutting cloth with scissors that are only used for paper would bend open the rivet and make them less effective - and also that cutting paper with scissors that are only used for cloth would dull the blades and make them less effective too. If scissors cut well providing they EITHER have a tight rivet OR sharp blades - but fail to cut will if they are both dull and loose - then the result would be that mixing the two materials would indeed prematurely wear out the scissors.
Now - to be 100% clear - I'm not seriously suggesting that this is literally the case - merely that it's not impossible for two different materials to wear out the same pair of scissors in two different ways and thereby render this seeming paradox correct.
In all likelyhood, it's all an old-wives tale and it doesn't matter a damn which scissors get used for what. My impression is that most people who do sewing keep a "good" pair of scissors for their work and simply don't want them to go missing as other members of the household take them for other purposes. The story of the aerospace guy with the padlocked scissors is almost certainly that. I mean - just how often would someone in a aerospace engineering workplace take them to cut fabric?!? It's much more likely that they'd often be "borrowed" and simply not returned. Hence the likely myth of incompatibility would serve the scissor owner's needs and would rapidly become lore and passed on to future generations...true or not.
Well, if it's filter paper, the person using whatever has been filtered might be touchy about pieces of thread, paper, and tape turning up in his liquid. Wnt (talk) 21:08, 7 January 2013 (UTC)
Along the same lines, there really can't possibly be a reasonable answer to this, if only because the umbrella terms "paper" and "cloth" can refer to any number of materials with varying physical properties likely to wear or provide stress on the scissors in different ways (to say nothing of the variables involved in the composition and form of the scissors, the cutting technique involved, maintenance of the blades, whether they are used continuously or intermittently, and just a whole huge mass of other factors). Certainly it's clear that, especially in an industrial context, many different types of scissors have been developed for specific tasks and materials. Snow (talk) 07:54, 8 January 2013 (UTC)
Yes, so again, there isn't necessarily a paradox in the idea that scissors that are designed for cutting cloth might be ruined by cutting paper - and vice-versa. However, I still very much doubt that people who cut cloth using $10 scissors bought from the needlework department at WalMart would be able to detect any significant blunting from using them to cut paper occasionally. All I'm trying to point out to our OP is that the seeming paradox of opposing views on scissor blunting doesn't (by itself) disprove either of the opposing theories that the various sides of the debate are proclaiming. Someone needs to do some experiments. Take two identical pairs of scissors - measure their initial cloth-cutting capabilities - then use one to cut 100 meters of cloth and another to cut 100 meters of paper - then re-measure their cloth-cutting abilities. If there is a strong difference - then maybe there is something behind this. Then you need to re-do the experiment, reversing the role of paper and cloth. Obviously you'd need to repeat the experiment a few hundred times to be sure that the results were statistically valid. Since this is a whole lot of work - it's easy to see why we don't know the answer! SteveBaker (talk) 14:56, 8 January 2013 (UTC)
I can't speak for the relative wear rates of paper and cloth, but I have a pair bought 37 years ago on a market stall and used for everything needing cutting, and they work as well now as when new. The key might be a domed spring washer keeping the blades together. Semiable (talk) 20:46, 8 January 2013 (UTC)
I also have a pair of fairly ancient scissors that were probably made in the 1950's for cutting wallpaper. They are occasionally useful because they have unusually long blades and don't suffer from left-hander-hostility like so many modern scissors! They also cut well - and (as User:Semiable says), the important part is the part that keeps the blades together. I have no idea what they were originally fitted with - my father had them held together with a wing-nut and bolt with a spring washer. I find myself replacing that nut and bolt every few years when they wear out and start to need to be re-tightened annoyingly often. I've occasionally sharpened them with a Honing steel - but for me, the sharpness of the blades is a small matter compared to getting the tension right between them. SteveBaker (talk) 21:29, 8 January 2013 (UTC)
If you read the section of the article you just linked to which mentions 'sawback' bayonets, you will find a fairly comprehensive answer. But in summary: they are more damaging, but not necessarily more readily lethal, and they have a tendency to get stuck in the wound, rendering the attached rifle useless and the attached soldier a sitting duck. They are also viewed as needlessly cruel: if you're going to stab someone on the battlefield, doing so in a way that does not deliberately torture them if you fail to kill them outright is considered a good idea. AlexTiefling (talk) 19:05, 7 January 2013 (UTC)
I think they were only used by the German Austrian armies, where they were issued to pioneers and called a pionier-faschinenmesser ("pioneer fascine knife"). A fascine was a large bundle of sticks used in field fortification or trench-crossing. Otherwise, I agree with Alex's comments above. Alansplodge (talk) 19:41, 7 January 2013 (UTC)
So I take it those were dual purpose, to be used both as weapons and as saws, to cut wood for fortifications ? StuRat (talk) 20:43, 7 January 2013 (UTC)
"During the day we loaf about and make war on the rats. Ammunition and hand-grenades become more plentiful. We overhaul the bayonets--that is to say, the ones that have a saw on the blunt edge. If the fellows over there catch a man with one of those he's killed at sight. In the next sector some of our men were found whose noses were cut off and their eyes poked out with their own saw-bayonets. Their mouths and noses were stuffed with sawdust so that they suffocated.
Some of the recruits have bayonets of this sort; we take them away and give them the ordinary kind.
But the bayonet has practically lost its importance. It is usually the fashion now to charge with bombs and spades only. The sharpened spade is a more handy and many-sided weapon; not only can it be used for jabbing a man under the chin, but it is much better for striking with because of its greater weight; and if one hits between the neck and shoulder it easily cleaves as far down as the chest. The bayonet frequently jams on the thrust and then a man has to kick hard on the other fellow's belly to pull it out again; and in the interval he may easily get one himself. And what's more the blade often gets broken off."
I should add that apparently there's some confusion on the web about this point, with people talking about it being variously improper to use notched, sharpened, dull, or rusty bayonets - one source ties it to the 1899 Hague convention against "To employ arms, projectiles, or material of a nature to cause superfluous injury;". If you ask the Humanities desk I bet you'll get a better answer. Wnt (talk) 20:44, 7 January 2013 (UTC)
Thanks for that quote Wnt. That explains why they weren't used after WWI; I haven't got a reference for that, but a thorough Google only revealed 19th and early twentieth century examples. Alansplodge (talk) 22:33, 7 January 2013 (UTC)
There was a question about serration on swords on the Ask a historian subboard of reddit just yesterday, and it included a fairly long discussion on serrated bayonets as well. Consider looking there as well, if it's not precisely that discussion that started you on this tangent. 164.71.1.222 (talk) 06:00, 8 January 2013 (UTC)
Worth mentioning is that bayonets are almost never used for stabbing enemy soldiers. Some years ago, I came across a list dating from the American Civil War of things a bayonet was useful for (candle holder, utility knife, cooking spit, etc.), and most of them work better with a non-serrated bayonet. --Carnildo (talk) 03:47, 9 January 2013 (UTC)
January 8
How strong magnetic field at a distance from a magnetic source?
This is not enough information to solve for the field strength at one meter distance. If you provided information about the source, we could estimate the strength at other points. For example, our article on dipoles provides a simple formula for calculating the magnitude of a dipole source. Many magnetic field sources are well-approximated as dipole sources. Nimur (talk) 01:19, 8 January 2013 (UTC)
Er... magnetic monopoles have not been proven not to exist, they are perfectly valid in hypothetical scenarios, and at any rate that is the essence of Nimur's comment... 72.128.82.131 (talk) 02:21, 8 January 2013 (UTC)
The source is a speaker sub 8" with other magnetic sensitive equipment at 0.2 - 0.3 meters distance. The media is ordinary air. The only obstacle may be tree panel ~2cm thick. Electron9 (talk) 08:48, 8 January 2013 (UTC)
You still have not provided sufficient information. Firstly, there are two main types of speaker magnetic circuit construction: 1) cylindrical magnet in centre and soft iron flux return circuit outside; 2) Soft iron pole piece centre and magnet in the form of a toroid on the outside. Type (2) is normally used if the magnet is a ferrite magnet. Because the flux density of ferrite magnets is less than for metal types, ferrite magnets are usually oversized so that the pole piece is saturated or close to saturation. This means a lot more flux "escapes" with type (2) magnet systems. Also, the amount of flux at the distance range you indicated will depend on the diameter of the magnet system - this can vary 2:1 or more for the same size speaker overall diameter. The amount of flux that "escapes" also depends on the voice coil gap - the wider the gap the more flux escapes. Hi fi speakers are often made with ferrofluid lubricant in the voice coil gap - this will reduce the amount of escaping flux. The construction and material used for the speaker frame/basket will also have an influence. Be aware that speakers are available in low field models - these have a surrounding magnetic shunt to contain flux that would otherwise escape. These speakers were developed for use in TV sets with cathode ray tube (CRT) displays - such displays are rather sensitive to magnetic fields, especially colour displays. A high efficiency high quality speaker made for car radio applications can have an external magnetic field very considerably stronger than that of a speaker made for a cheap TV set.
All this means that, unless you have access to comprehensive magnetic circuit data from the manufacturer, the amount of external flux will be impossible to estimate and you'd be better off to obtain a candidate speaker and test it. If you have no means of testing, use a compass. Position the speaker so that it's field is at right angles to the Earth's magnetic field at your location, as shown by the compass. Move the speaker towards the compass so that the compass needle deflects. You can then calculate approximately the field strength of the speaker flux as a fraction of the local Earth magnetic field strength from the angle of deflection. For instance, a 45 degree deflection would indicate identical strengths.
How sensitive is your sensitive equipment anyway? I have some quite standard 8 inch speakers that produce no deflection of a compass at a separation of 200 mm. Keit 58.170.141.154 (talk) 10:28, 8 January 2013 (UTC)
As data on the speaker is missing. Perhaps one can figure out how many times less the field is at a distance than at the magnetic source ? A compass also has some inertia (but I like the idea). Electron9 (talk) 13:14, 8 January 2013 (UTC)
No. You could, if the point of interest was remote from the magnet, determine the fall off at another point even further away, as you could then assume a far field from a simple round rod magnet (the proverbial spherical cow approach). But you said you are interested in a point as close as 200 mm from an 8 inch (200 mm) speaker. Even if you assume the frame to be non-magnetic, if the speaker has a type 2 magnetic circuit (as I described above), the diameter of the magnet toriod will be around 50 to 80 mm. This puts you in the near field, so a far field approximation cannot be used. And you would still have to make a field strength measurement anyway for the reasons I gave - you haven't identified the magnet structure (type 1 or 2 or some other), you haven't identified the magnet diameter, presence or not of magnetic shielding/shunting etc etc. You gave the magnet strength (2.4 Tesla) but if this is speaker manufacturer's data it will be the total flux in the voice coil gap. Almost all of this flux is contained within the soft iron return circuit and shield (if fitted for TV use). You don't know how much of it escapes outside the speaker structure, but it will be a very small portion.
To see what I am talking about using the terms "far field" and "near field" consider a rod magnet of some arbitary area x mm having a total internal flux y. Close up at the poles, the flux density will be y/x. Close to the sides it will be less. At a point z metres far from it the flux density will be then (y/x).k where k is a reduction constant depending on distance and bearing relative to the magnetization axis. There is a standard formula for calculating k - Nimur gave you the link - but that need not concern us now. Now, take a second magnet made of the same material, but twice the area. Clearly, close up the flux density will be y/x i.e., same as for the first magnet. But at the far point the flux density will be 2(y/x).k, twice as strong as with the first magnet.
The inertia of the compass needle is of no importance whatseover, as you only need a stable deflection off normal.
Thirty seven...I think...the history of these things is complicated, confusing and very ugly! According to the last two sentences of our IC4 article: "In November 2011 two IC4 trains each failed to stop at stop signals. This caused the authorities to ban the IC4 from running until the problems had been investigated. The investigations are currently ongoing." ...and... "On 2 July 2012, the DSB announced that Trafikstyrelsen (Transportation Authority) has approved the Danish railways to be able to put into service the park 37 IC4 who had been withdrawn from service in November 2011."
So if they'd all been withdrawn from service in 2011 - and 37 put back into service last July - then there are (presumably) 37 in service today....although I suppose it's possible that more have entered service in the past 6 months...or that although DSB was approved to put 37 back into service, they might not have done that for whatever reason. Those possibilities aren't mentioned in our article or the sources it references - so the best answer I can find is "thirty seven". SteveBaker (talk) 13:22, 8 January 2013 (UTC)
Well, the answer is a bit complicated. Let's shoot for something simple and let the guru's here complicate the answer to the point that neither of us will be able to understand it!
Electrons are often thought of as tiny little balls that go around the nucleus of an atom like planets around a star - that's a nice mental image - but it's not really true. The "truth" is a bit different from that. At the level of atoms, the world isn't like the familiar world of human-scaled things. Particles are waves and waves are particles - mass and energy are the same thing. That's true at the scale of humans too - but it's very hard to tell. But at the scale of an electron, those weird things come to dominate any explanation. Nothing has a definite location. So an electron is more like a fuzzy cloud of "probability" - that's to say that the exact location of the particle isn't a definite thing - all we can ever know is that it has some probability of being at some point - and that probability is higher here than it is there. When you consider that, the questions you pose stop making any real sense.
Adapting my answer from this old thread: electrons do fall into the nucleus. The electron of a hydrogen atom doesn't orbit the proton, it's simply superimposed on it. They don't collapse to a point because the uncertainty principle forbids it. A decrease in position uncertainty beyond a certain point implies an increase in momentum uncertainty which leads to an increase in position uncertainty. Instead they settle into an equilibrium state where these two effects balance out. The electron ends up with a much larger uncertainty of position because its much smaller mass means that a small uncertainty of momentum counts for much more in terms of velocity. That's why the atom looks like a small nucleus of positive charge surrounded by a big cloud of negative charge.
When there are more electrons, the exclusion principle means that they can't all sit in the same place as the first one, so they end up in higher-energy states. Some of these are just more energetic versions of being superimposed on the proton (2s, 3s, etc.) while others (p, d, f, etc.) have angular momentum, making them more like orbits. The motion (if you can call it that) is nonetheless quite chaotic because of the uncertainty principle; the electron ends up spread out over the entire orbit. But electrons far from the nucleus in a Rydberg atom can have orbits that look almost like planetary orbits for a short time. Electron orbitals and planetary orbits are two extremes of the same thing. -- BenRG (talk) 17:42, 8 January 2013 (UTC)
Related question: From the formula of the 1s orbital, it looks that the electron is more likely to be within the nucleus than in any other shell of equal volume (i.e. with positive inner radius). Is that right?
Sub Questions
It is clear that electrons do not move in orbits, but still I have some confusions. Do electrons move around nucleus or they remain at the same site ? If a electron is not at rest, the orbital in which it lie should also move with this electron. Does this happen ? Can a electron change its orbital ? Parimal Kumar Singh (talk) 13:26, 9 January 2013 (UTC)
Is Anthropogenic Global Warming falsifiable?
I had an epistemological question which has to do with the fact we probably can't reverse the continuing increase of greenhouse pollutants which are posited to be the inextricable causes of global warming, thus losing the chance to conduct an experiment to determine whether reducing our greenhouse emissions will lead to a cooler climate. If anything were possible, we would create a perfect clone of earth and make everyone live 100% perfectly "green" while this earth continues the status quo, thus a replicable experiment that can be repeated dozens of times with identical outcomes that would be unassailable.
Background from here it says "NOAA: 2012 was warmest year ever for US, second most 'extreme'" & it is reasonable to say that both "global warming" is going up & so are the "greenhouse pollutants" going up also. However, correlation does not always imply causality.
I used to be a non-believer of AGW due to this page and also because of the climategate scandal, but now that I'm beyond the politics & the election is over, I can finally ask my question here on the reference desk without people bashing mitt romney or republicans (knock on wood!)
So here is my honest, legitimate question: do the 95% of scientists who are in concensus that AGW is real & caused by humans and/or meaningfully exacerbated by humans even though the earth might be warming as we speak if humans were all dead--do those same zealous scientists have weather predictions they definitively stand by? (such as 6 outta the next 10 years will be hotter than any of the last 100 years unless we cap greenhouse gases)
I'm agnostic now about AGW and do not feel like I can learn anything more from wikipedia about AGW after reading the articles without asking for some human assistance from those at the ref desk knowledgeable about the epistemological basis for how do we know what 95% of scientists believe. This is also a chance to share knowledge with someone who is ready to listen to someone on the pro-AGW camp of Wikipedians. Thanks in advance for any answers or book recommendations or online resources that are provided. Bests, the Tomato expert1 (talk) 19:03, 8 January 2013 (UTC)
The short answer is yes. However, many of the most publicised predictions are ones which, if they come true, will mean that we are already too far gone. I would be interested in shorter term predictions such as you suggest. Personally I am fairly firmly convinced of AGW, but that's mostly on the basis of retrospective studies. I am therefore interested in the short- to medium-range predictive power of the theory.
However, as a former student of chaos theory, I'm bound to observe that the weather is an intrinsically difficult subject, and so a prediction being met would not absolutely guarantee the theory, nor would a prediction being missed completely falsify it. As using less power is cheaper than using more, and we are running out of fossil fuels anyway, I find it pragmatic to act as though the theory were watertight; I don't think I can reasonably lose out that way. AlexTiefling (talk) 19:13, 8 January 2013 (UTC)
PS: Delingpole's critique is not based in science, but in a frankly paranoid conspiracy-theory view of the scientific community which cannot reasonably be taken seriously. This response to his blog is instructive. AlexTiefling (talk) 19:18, 8 January 2013 (UTC)
Firstly, I think that our use of vocabulary here is crucial. The greenhouse gas emissions problem is not about "weather" - it is about "climate" - the difference is crucial. The overall climate of the planet changes fairly slowly and somewhat predictably. Weather is chaotic (in the mathematical sense) - so no prediction of weather change is either proof or counter-proof of anything very much. The word "warming" in the term "global warming" is distracting because the weather in some places in the world will not experience a temperature increase - and might even feel a decrease (eg if the north atlantic conveyor current reverses) - and people can only directly experience "weather" - you need a ton of complicated science and statistics to measure "climate". So it would be better to stick with "global climate change". Furthermore, climate change is only one result of the prediction of the effect of greenhouse gas increase - others include sea level rise, loss of arctic and antarctic ice, the diminution of glaciers and so forth, increased chaos in the day-to-day weather of most of the world. Obviously these effects are all inextricably linked.
Equally obviously, the climate change prediction of greenhouse gas emission increase is falsifiable. If we went for 100 years with the average temperature of the atmosphere decreasing steadily while greenhouse gas emissions continued to increase - then the theory would be proven false. This most certainly isn't a matter of falsifiability. It's a matter of whether the theory is true or false. (Being shown to be true or false is not related to the issue of falsifiability. An unfalsifiable theory is one such as the existence of God. We can't prove it false - there is simply no conceivable way to do that. We also can't prove whether we live in a computer simulation of the universe - that's also unfalsifiable.)
So we are beyond falsifiability. It's climate change due to greenhouse gas emissions is falsifiable...for 100% sure.
The important question for unbelievers is now "Is it false?" - which is not at all the same thing as "Is it falsifiable?"
The question of whether predictions have been made that came true is one solid way to show that some theory is likely to be true. So one prediction is that average temperatures around the world would increase...and they have. Another is that polar ice would retreat - and it has. Another is that migratory animal species would live at latitudes increasingly far from the equator - and they are indeed moving that way. Yet another is that while the climate would slowly warm, the actual weather would become more extreme, and that too is clearly true. So there are a TON of predictions that are playing out - and they are fairly consistent in showing the truth of the theory.
But it's extremely hard to prove any scientific theory beyond all doubt. After all, there is always the possibility that some extremely powerful extraterrestrial being is dead set on messing with our heads by screwing with our experimental equipment. You can't absolutely, 100% prove or disprove anything. That's really why this rather vague-sounding word "theory" is used in the sciences when "fact" would have a nicer ring to it. In the end, we have to say "With all that we've looked at - is the balance of evidence that we should take extreme emergency measures to combat the release of greenhouse gasses?" - and to that level of satisfaction, there is no longer any reasonable doubt that global climate change is real and that emissions of CO2 and methane that we have made are by far the biggest culprit.
Sure, we might be wrong (I'd give it a one in a thousand chance) - but the consequences of cutting emissions drastically when we didn't need to are so vastly less than the consequences of inaction if we're correct, that if there were even a small chance that we're correct, then there really shouldn't be any doubt as to the smartest course of action for all humans everywhere.
Oh - and your figure of 95% of scientists believing in climate change is out of date. In 2011, the percentage of scientist believers was over 97%. More importantly, the few percent who did not express belief were not necessarily saying that they actually disbelieve - merely that they aren't convinced yet. The number of scientists who actively disbelieve is down below the threshold at which it can be reasonably measured.
...Just to add, a number of scientists quibble over minutia of details and definitions. So, they may be "skeptical" about certain statements; or they may "disbelieve" certain conclusions; but it would be inappropriate to say that they do not believe in climate-change or human effects on climate. My take is this: "anthropogenic climate change" is not a hypothesis: it is not a statement or prediction that can be tested; so it's invalid to call it "true" or "false;" or even to say one "agrees" or "disagrees" with it. You might as well ask if a scientist "agrees" with impressionist painting, or whether "impressionism" is falsifiable. This phrase, like "anthropogenic global warming," encompasses an entire field of study, a roughly-agreed-upon body of known work, and a whole bunch of opinions about those works; the name of the field is not, in itself, an assertion or prediction that can be tested. A better question should be used to query a scientist's position, or their confidence in the evidence. For example, "to what extent do you believe CO2 concentration determines the total warming?" The response to that type of question would be a scientist's evidence-based opinion; or a statement of fact; or a hypothesis that could be proven true or false. Nimur (talk) 20:50, 8 January 2013 (UTC)
Also "believing in climate change" needs to be defined. The number of scientists that believe that it isn't changing is smaller than the number of scientists that believe that humans have little do with it, which is smaller than the number who believe that climate is changing and humans are largely the cause but don't believe that it is stoppable, which is smaller than the number who believe that climate is changing and humans are largely the cause but don't believe that it is stoppable by the US and Europe if China, India, Africa and/or South America don't cooperate.
1) Most scientists prefer to call it "global climate change" rather than "global warming", as a few spots may actually get colder (like Northern Europe, if the thermohaline circulation fails).
2) Random variations swamp out long-term effects in the short run, making it quite difficult to predict the climate for the next few years. Only the long-term trends can show changes regardless of these random events. StuRat (talk) 21:05, 8 January 2013 (UTC)
Climate scientists definitely do have quantitative climate predictions, and you can help with the prediction yourself. See this distributed computing project, which also includes links to some of the papers they've published.
The question of falsifiability is not as simple as asking whether you can do a controlled experiment. Obviously it's not possible to create another Earth to see whether carbon dioxide is the cause of warming, just like it's not possible to create another solar system to see whether Mars' orbit is due to gravity. All we can say is that we have a model of gravity that worked in the past, there's no reason to suspect it wouldn't work for Mars, and it correctly predicted where Mars would be for millenia, so it's reasonable to trust the model's predictions of the future. Climate is vastly more complicated and harder to predict than gravity, not to mention we have much less data to work with, but the essence of climate modelling is to find a physically reasonable model that accurately explains the past climate and apply it to predict the climate 20 years from now. In 20 years, the model could easily be proven wrong--if the global climate was predicted to increase by 1 degree but instead decreased by 4, a change that's easily measurable with modern instruments, the model is inaccurate. --140.180.245.22 (talk) 21:45, 8 January 2013 (UTC)
To elaborate on Steve's points above: The crucial bit is the difference between weather and climate. Weather is a chaotic process, and looking sufficiently far into the future, weather (say the weather in 3 weeks time, or even whether next summer is going to be a hot one) is essentially random. No person, scientist or not, can predict the future. Climate on the other hand is aggregated weather. Climate is the likelyhood of having a particular type of weather. Mathematically, climate is the probability distribution of weather. The crux is that even if the individual events are random/unpredictable, the probability distribution itself is not random and we can build fairly robust models for it. Robust enough that these can be falsified, given enough data. A single data point (like the US average summer temperature in 2012, or a cold spell in Russia) is not going to tell you anything, but given 20 or so years of observations, you can make quite firm statements such as the likelyhood of seeing this pattern without climate change would have been unreasonably small. Much depends how you define unreasonable, but given enough data you can falsify (or proof) at any threshold level. So yes, climate change certainly is falsifiable. A more interesting question is whether it is falsifiable or provable with the data we are able to gather before it is too late to take action. I fear the answer is probably not. As to whether scientist can make weather predictions that they can definitely standby: No, certainly not. Probably never. Weather is random, chaotic, too complex for predictions. But that's not the fault of the scientists and certainly not a fault with global warming. It is just the nature of the beast. Predictions about climate are entirely different. 86.185.161.4 (talk) 00:05, 9 January 2013 (UTC)
Note also that different parts of the AGW theory make quite specific and testable predictions. We can directly observe the changes in the infrared spectrum of earth caused by atmospheric CO2 using satellites like IRIS. We can measure the Suess effect to confirm the fossil sources of CO2. And so on. --Stephan Schulz (talk) 13:54, 9 January 2013 (UTC)
The way to think about the relationship between climate and weather is what many other sciences call principles of mass action. In chemistry, for example, the position and specific motion of individual molecules are not predictable, but that doesn't mean we can't describe the properties of a substance. The properties of a steel canister filled with oxygen are extremely well understood and consistent, though the specific motion of a specific molecule of oxygen is not. It's the exact same way with weather and climate: in climatology a single year's weather is the "molecule" while climate is the "tank of oxygen". --Jayron3214:01, 9 January 2013 (UTC)
I think a better question for someone to ask is how much of their money should be spent on various options considering their personal values. If a doctor says you have cancer and there's a 90% chance of you living more than 5 years if you have some operation do you have the operation? I'm sure Delingpole could find lots of surgeons who have botched operations or papers casting doubt on various techniques, does that mean you ignore the doctor or does it mean you take a second opinion? If 9 out of ten doctors say go for it what then? Does a general say "I don't know exactly where the enemy is, therefore I won't do anything"? They try and work out the best thing to do, for a general that might even mean tossing a coin sometimes! Too much of this looking behind by people who are not qualified in the minutiae strikes me rather like this . Dmcq (talk) 15:12, 9 January 2013 (UTC)
How Ears and Eyes Extract Frequency?
I know that we can extract frequency information from raw signals using methods such as FFT, but how do our organs do it without any apparent computation?
75.228.142.113 (talk) 19:50, 8 January 2013 (UTC)
For the eye: most studies indicate that the extraction of spatial frequency is performed in the brain, not the eyeball. This naturally becomes pretty complicated in a hurry; but you can start by reading this website, the "Cornea Lab" in the Vision Science Program at Berkeley; here's a good starter paper, on spatial frequency selectivity of human vision; it cites dozens of books and papers for background reading. The extraction of frequency of light - in other words, color, is performed inside the specialized cells of the human retina: what we commonly call the cone cell. These cells contain photochemical that makes them selectively receptive to photons of specific color (frequency of light).
Finally, you might be surprised at how straightforward it is to build a discrete cosine transform to extract spatial frequencies out of a focused optical system. This can be expressed mathematically through the framework of Fourier optics. A fast fourier transform isn't necessary, because such machinery works in the analog domain and does not depend on sequential digital calculations. You can extract spatial frequencies simply by intelligently combining signal levels from various combinations of the input (i.e. the retina cells) when stimulated by a focused image. This is the exact analog representation of computing the inner product of the image against each basis-function in the transform domain. Nimur (talk) 20:15, 8 January 2013 (UTC)
For the eye, we have to be careful to distinguish the frequency of the light from spatial frequencies and even temporal frequencies (eg strobe lights).
The light frequency isn't measured at all well - at least not compared to the ear. We have three kinds of color sensors that detect light as amount of energy within a range of frequencies with a roughly gaussian fall-off. The center frequencies of the three kinds of cell are at the colors Red, Green and Blue. We perceive pure yellow light (eg from a sodium lamp) because both the red and green detectors are producing a mild response and the blue is not. However, to use an acoustic analogy, a "chord" of red and green light looks exactly the same as yellow light - we literally can't tell the difference. It's as if a chord of the C and E keys on a piano sounded exactly the same as the D key by itself! Another set of cells detects the overall brightness of the light and is more sensitive to motion.
The spatial frequency appears to be an ugly mixture of pre-processing in the retina and post-processing in the brain. There isn't enough bandwidth down the optic nerve for each cell to report back to the brain individually - so we know that there is a considerable amount of pre-processing going on in the retina. We know that edge-extraction happens in the retina - and that's a component of frequency analysis. Everything is very much complicated by the fact that our eyeballs continually vibrate in their sockets - this scans the scene with the retina to eliminate "pixellation" such as you get with a TV camera. If a camera with the same number of pixels as the retina is used to take a picture, you can see the individual pixels - but the eyes don't do that because of this vibration. That increases our spatial frequency perception beyond the resolution of the retina. When your eyes get tired (or you get drunk!) this vibration ceases and your vision goes blurry - that blurry vision is the "natural" resolution of the eye. All of this complication greatly enhances the difficulty of answering this kind of question!
Temporal frequency is another strange thing. We don't see single "frames" of video like a TV or a film projector - instead, we're getting signals from the retina like "An edge, sloped at 45 degrees is moving left to right at such-and-such speed"...but it's not a discrete time-sampled signal - which is why we don't see strobing and temporal aliassing in normal daylight.
Interpreting the way the eye works as an analogy of a digital camera is a very bad idea! The entire system from the mechanics, the optics and the image-processing "circuitry" works totally differently to any man-made camera. SteveBaker (talk) 21:12, 8 January 2013 (UTC)
"The center frequencies of the three kinds of cell are at the colors Red, Green and Blue" is false, as I and others have pointed out to you repeatedly in previous threads. As shown here, two of the cone types are maximally sensitive in the yellow-green-cyan range, and the third peaks in the violet.
The claim that microsaccades increase the eye's effective resolution doesn't seem to be backed up by the article. The eye, unlike cameras, has a fovea, and we can see any small part of a scene in great detail by pointing the eyes at it, but those are large eye motions, not tiny vibrations. Everything outside the fovea is very blurry. The smallest microsaccades (according to the article) move about 2 arc minutes, which is several times the separation of photoreceptors at the center of the fovea (about 0.5 arc minutes).
"When your eyes get tired (or you get drunk!) this vibration ceases and your vision goes blurry" is wrong. The actual cause of the blurred vision (and seeing two of everything) is a failure of accommodation. -- BenRG (talk) 23:18, 8 January 2013 (UTC)
liquid nitrogen condensing liquid oxygen
From Liquid nitrogen: "Vessels containing liquid nitrogen can condense oxygen from air." Is there an upper limit as to the percentage of liquid oxygen that gets condensed?Dncsky (talk) 22:23, 8 January 2013 (UTC)
Here's the article's source: . I don't see an upper limit. If all the liquid nitrogen has evaporated, this may leave a small quantity of near 100% liquid oxygen (with maybe some dry ice and water ice mixed in). StuRat (talk) 22:37, 8 January 2013 (UTC)
That was actually my follow-on question, you mind reader you. Can someone else just confirm this: if I leave a bottle of liquid nitrogen in the open, it'll become a bottle of liquid oxygen (with impurities) at one point.Dncsky (talk) 22:56, 8 January 2013 (UTC)
I missed "at one point" in that sentence. I've added it now. I'm basically asking for a confirmation on what StuRat said. Dncsky (talk) 23:53, 8 January 2013 (UTC)
I'm not even sure that's the case, except in carefully controlled conditions, where the ambient temperature is below the boiling point of oxygen but above boiling point of nitrogen (between the window of 77 K - 90 K). At room temperature, trace amounts of liquid oxygen are probably forming within the liquid nitrogen, but these probably boil off along with the nitrogen, to the point where it never makes up a significant portion of the liquid. --Jayron3201:30, 9 January 2013 (UTC)
Doesn't that contradict the article though? It's saying "increasingly enriched in oxygen", but you're saying it's just trace amounts. Maybe I'm misunderstanding what the article meant.Dncsky (talk) 02:30, 9 January 2013 (UTC)
(edit conflict)You'd need some special geometry of your container to get a noticeable amount. Boiling (i.e., evaporating) LN2 has N2 gas streaming off of it, which makes it hard for much room-air (source of O2) to reach the LN2 and condense in. I've left LN2 dewars and flasks open until it's all gone, and I usually have little if any water-ice in the bottom even in humid labs, but I do get water condensing on the still-cold glass surface after the LN2 has evaporated. DMacks (talk) 01:31, 9 January 2013 (UTC)
Actually, what DMacks reports is true only under limited (but very common) circumstances. Often, the evaporating LN2 pushes all O2 away from the surface, which can fool you into thinking it always works that way. If you have a container with a wide mouth and a cross-breeze you will definitely end up with all the LN2 boiled away and a smaller amount of pure LO2 in the container. Also, if you put LN2 in a regular (non-dewar) metal container, LO2 will condense on the outside, as seen here:
"Liquid nitrogen will condense oxygen from the air. This is most alarmingly demonstrated if a person leaves his/her vacuum pump's coldfinger in a Dewar of liquid nitrogen overnight. In the morning the coldfinger will contain LIQUID OXYGEN up to the level of the nitrogen in the Dewar." --Guy Macon (talk) 11:28, 9 January 2013 (UTC)
Thank you very much, Guy! After reading the LN article I just thought to myself: "How cool is it that when I leave substance A out in the open it'll turn into substance B! And B isn't even chemically derived from A in any fashion.". StuRat confirmed my suspicion and how you found the source to back it up. Thanks again. Dncsky (talk) 18:55, 9 January 2013 (UTC)
Rainbow colored clouds?
I was just on my way home from work today and in the south-western part of the sky, there was a cloud that appeared to be in the colors of the rainbow - yellow, red and faint blue in that order from right to left. The Sun was to the right of the cloud. I've seen plenty of rainbows before, but they accompany rain and span across the sky. There was no rain (that I am aware of) and it was localized in a very small area of the sky - just a portion of some clouds. I observed it for a good 10-15 minutes at least.
I tried to take pictures of it with my cell phone, but I was driving and it was almost impossible to keep the Sun out of the frame. I can try to upload a picture to Commons if any of them came out alright.
So, here's my question: Can anyone tell me what I just saw? I can't recall ever seeing anything like this before.
In case it helps, this was in the Chicagoland area and it was about 4pm local time.
A Quest For Knowledge (talk) 22:54, 8 January 2013 (UTC)
Sunset was at 4:37 PM in Chicago today , so the Sun was low in the western sky. I suspect there was some distant rain, which the sunlight shone through, causing it to be diffracted, before it struck the clouds. Looking at a weather map, there does seem to be rain coming in from the West, so perhaps that was the first little sprinkle. StuRat (talk) 23:58, 8 January 2013 (UTC)
A rainbow is water droplets glistening in the sun. The physics determine that the colour they appear to you depend on the angle formed by the sun, the water droplet and the observer, creating the illusion of the rainbow. It does not have to be falling water, but can be mist, fog, or even clouds given the right conditions. The rainbow article has pictures of quite a few different examples. 86.185.161.4 (talk) 00:19, 9 January 2013 (UTC)
Or it could have been a circumzenithal arc (which is basically a rainbow but reflecting off ice crystals in the clouds rather than water droplets). What is the temperature in Chicago at the moment? 86.185.161.4 (talk) 00:33, 9 January 2013 (UTC)
Likely to be substantially colder at cloud elevation. I was thinking of CZA, too, given that the sun was low in the sky and the mercury was low as well. -- Scray (talk) 01:01, 9 January 2013 (UTC)
My copy is buried somewhere as a result of moving, but what you saw is almost certainly described somewhere in The Nature of Light and Color in the Open Air: Minnaert covers just about every atmospheric optical effect in it. --Carnildo (talk) 04:03, 9 January 2013 (UTC)
Hmmm...well, there was no discernable arc to the rainbow and it was a very, very small portion of the sky. Anyway, I Googled (well, Binged) for images this morning (I have no idea why I didn't think of that last night) and here's a few that are kind of what I saw.A Quest For Knowledge (talk) 14:31, 9 January 2013 (UTC)
OK, here's one of the pictures I took yesterday. You can barely see the colors of the rainbow and it looks a lot brighter than it did yesterday. In fact, it kind of looks like a comet or a UFO. The Sun is on the far right, and the 'rainbow colored cloud' is towards the center (slightly offset to the right).
Well, I definitely see clouds, so that supports the idea of sunlight passing through water vapor (or ice crystals). StuRat (talk) 20:45, 9 January 2013 (UTC)
a map showing the international date line in the middle
I would like to be able to see a world map with the international date-line more centred. (in one piece) - ie: i do not want to see part of the one side of the date-line SQUEEZED in on the right- and the other part SQUEEZED in on the left of the whole image/picture/diagram.
Looking at an existing time-zone map of the world, a more convenient split would be somewhere between 30 to 60 (degrees) West longitudes - as this looks like a longitudinal zone with the least breaks or "zig-zags".
How many times can a hand grenade realistically bounce off a wall before either coming to a stop or exploding, whichever comes first? Assume that: the grenade in question is a German stick grenade with a standard 5-second fuse, thrown at the wall at a 45 to 60 degree angle as hard as possible; the thrower is tall and has long arms but only average strength; and the walls are concrete and about 3 feet apart, forming a narrow passageway. 24.23.196.85 (talk) 06:46, 9 January 2013 (UTC)
It could only bounce of a wall once. If you mean bounce between two walls, that would depend on how high along the walls it hit initially, it's angle relative to the ground, and it's initial speed. The don't bounce very much, so it would have to be going quite fast to bounce more than once or twice. StuRat (talk) 06:53, 9 January 2013 (UTC)
It still depends on the width of the passageway (imagine a passageway 100 feet wide - there could only possibly be one bounce...now imagine a passageway only a foot wide - and there would obviously be many bounces)...also the height at which the grenade initially hits the first wall...if it hit the first wall very low to the ground then fewer bounces than high up. Then we need to know the speed of impact, the angle of the impact...there are just far too many variables.
Worse still - they have a very irregular shape - how it hit (stick first, head first, sideways) would make a massive difference. The rate and direction of rotation would add a complicating factor. Also the head of the grenade was very thin metal - it would likely dent easily - absorbing energy from that first bounce and drastically reducing it's speed. But if the stick hit first - it's wood, flexible like a very stiff spring - so it would probably retain most of the energy providing more rebound.
If you want to get even more technical - our article says that the 1942 and later versions had a serrated steel sleeve that could be optionally be slid over the head to get a greater fragmentation effect in anti-personnel applications - which would really complicate matters in a head-first impact because the serrations would result in a much more random bounce/spin.
Gut feel says "once"...or maybe "not at all" - but there are too many variables to come up with any kind of informed answer.
If I were you - I'd take a foot of broom-handle and firmly duct-tape a 500g can of soup to the top - then get out there and try it! Nothing short of tossing one around yourself will give you the authentic "feel" you need for how they would bounce.
Not soup. Anything liquid will slosh and act as a damper. Something solid enough to not slosh when you shake it is better. A can of chili or dog food should do the trick.
I am guessing that straight on to the wall will give you maybe a one foot bounceback, but a glancing hit will retain most of the velocity -- but make the next wall effectively farther away, so maybe two bounces. I really want to see pics of this. Do it! Do it for SCIENCE!! <smile> --Guy Macon (talk) 15:56, 9 January 2013 (UTC)
Good point about the liquid thing...but most regular cans are only about 250 to 350 grams - I was thinking specifically of the larger diameter cans that might weigh more like the 560 grams that the real grenade weighed...minus the weight of the stick...so a 500g soup can would have about the right weight. I've seen dogfood in those larger cans though - that would work. SteveBaker (talk) 17:31, 9 January 2013 (UTC)
@24.23.196.85, are you asking this because you want to incorporate it into a graphic novel, film script, story, or other work of fiction? If so, one, maybe two bounces would be the limit of "realistic". But if you're going for exaggerated violence a la Tarantino, have it bounce as many times as you want! - LuckyLouie (talk) 16:29, 9 January 2013 (UTC)
I suspect that one bounce (or possibly no significant rebound at all) is the most likely "realistic" outcome - but two bounces and some rolling would seem "credible" to me - especially in a book where your imagination gets to roam free. It might be harder to make it believable in a movie though. Our article on the later Model 43 grenade suggests a detonation delay of 5.5 to 7 seconds...which might help to extend any exciting rolling and/or bouncing and/or being-"fetched"-by-a-stray-dog deemed necessary for the plot. SteveBaker (talk) 17:28, 9 January 2013 (UTC)
That was my plan all along -- a bank shot to send the potato-masher behind a partition in order to take out a German machine-gunner. Based on the layout of that particular pillbox, I can do it with two bounces, but I'll have to shorten the partition somewhat to make it happen. :-) BTW, I like the experiment you suggested, but the one thing to which I don't have access is concrete walls 3 feet apart -- all the walls around me are made of wood. Will that make a significant difference? 24.23.196.85 (talk) 00:19, 10 January 2013 (UTC)
Does it really matter that it's a stick grenade? The German army also issued "egg" grenades (Model 39 grenade) - and it seems much more credible that one of those would bounce and roll around much more than the ungainly stick models. The article on the Model 24 grenade actually says that one of the benefits of the stick design was to prevent it from rolling on hilly terrain - so if the plot requires that the grenade take some complicated path to it's target - then an egg grenade would be a better choice. SteveBaker (talk) 17:44, 9 January 2013 (UTC)
1) Kind of. If the horizon is absolutely flat, then yes. However, hills or mountains or even snow drifts mean that as the Sun corkscrews up and down it will pass behind them and then come back out, so you will get multiple "sunsets" and "sunrises".
2) It's so cold in summer because the Sun is at such a shallow angle. In winter, it's far colder because there's no sunlight at all, for months at a time. Also, prevailing wind direction is East-West, meaning very little warm air moves in from warmer areas. StuRat (talk) 08:14, 9 January 2013 (UTC)
At the south pole east is clockwise when looking down and west is anticlockwise. Opposite at the north pole. So in winter time you will not see stars rise in the east and set in the west, but they will just circle you. The point is that the wind does not go towards you to carry heat from outside. Graeme Bartlett (talk) 20:24, 9 January 2013 (UTC)
That's the point, the winds blow in a circle around the poles (more or less), not over them, where they would deliver warmer air. StuRat (talk) 20:21, 9 January 2013 (UTC)
Why do electrons, nucleons, stars, and planets have spherical shape ?
I have no microscope to observe electrons, protons, and neutrons in an atom, but I satisfy myself by only looking their pictures in books, on Misplaced Pages, etc. I usually see that they are spherical. Are they really spherical ? If yes, then, why not other shape ? Why do stars and planets have spherical shape, not other shape ? On the other hand, meteorites are not spherical but irregular. Why ? Parimal Kumar Singh (talk) 09:08, 9 January 2013 (UTC)
For the astronomical objects, gravity is the culprit. Large enough objects have enough gravity that it crushes anything that sticks up. However, if they rotate quickly, the shape is more of an oblate spheroid. For the subatomic particles, I don't think they really have a shape, just a probability density. It's just simpler to represent them as spheres. See probability amplitude for an alternative representation of an electron in a particular atomic orbital. StuRat (talk) 09:20, 9 January 2013 (UTC)
That isn't the electron. That's the region where the electron might be found. The electron itself, as far as anyone knows, is a point charge/point mass. Maybe something like string theory would make it something other than a point, but no one knows how to test it. --Trovatore (talk) 09:31, 9 January 2013 (UTC)
My point is that it's probability envelope is probably the best way to represent it, as that at least has some geometric definition. See atomic orbitals for some others. StuRat (talk) 09:37, 9 January 2013 (UTC)
I think that's a mistake. Admittedly it's one you see in writing from time to time, but still a mistake. To see the difference, note that, say, protons also have a probability distribution for where they might be found — but if you take that to be the "shape of the proton", then you completely lose the ability to talk about the proton's internal structure, with the three quarks floating around and exchanging gluons. The proton does have a shape, sort of, that being the shape given by the positions of the quarks, and definitely not given by the probability density function for position of the proton as a whole.
So the correct answer to "what is the shape of the electron?" is "no one knows; it might not have one at all", but is definitely not "the shape of its probability density function". --Trovatore (talk) 09:48, 9 January 2013 (UTC)
Regarding the proton shape: You've still got the same problem as with an electron, insofar as quarks are point particles like electrons, which themselves obey quantum rules and thus have the same problems with concepts like localizability and volume. So, since the "shape" of a proton is dependent on the "shape" and "position" of quarks (which is essentially as meaningless a concept as it is with electrons), so I don't think you can meaningfully discuss the shape of a proton any more than of an electron. Even the nucleus of the atom has a structure and a shape that defies easy definition. The smallest objects whereby shape takes on specific, definable, meaning are atoms and molecules, and even there there is some "fuzziness" (i.e. various ways to define atomic radius). --Jayron3213:39, 9 January 2013 (UTC)
Well now, hold on. The position of a quark is not "meaningless", it's just quantumly weird. The proton is a quantum superposition of infinitely many states in which all three quarks have precise positions, and each of those states has a precise shape (a triangle, though not the same triangle for each of the states), and where each of the quarks is, as far as anyone knows, a point mass. Anyway I agree that it's the same issue; that was kind of my point. I was explaining why the shape of the orbital is not correctly identified with the shape of the electron. --Trovatore (talk) 18:50, 9 January 2013 (UTC)
Wait a moment there! Take any three points in space and just try to position them so they aren't in a triangle! That's not "a precise shape"! Literally any position they might be in would be a triangle. (Albeit a "degenerate" one if they lay on the same straight line or two or more of them were at the same position).
A proton certainly has a size although what it is precisely isn't clear. And there are people looking at the shape of electrons.Sean.hoyland - talk19:04, 9 January 2013 (UTC)
Just glanced at it — is there anything there that's inconsistent with the hypothesis that the bare electron is a point mass? If so I didn't see it. --Trovatore (talk) 19:07, 9 January 2013 (UTC)
The strong force field of protons and neutrons is well approximated by a sphere with a diameter of about 1 fm within which the three "valence" quarks move freely. Electrons are point particles in a sense, but don't forget that the Standard Model is a quantized classical field theory. The quantization leads to pointlike behavior but there's a sense in which electrons can spread out even at the classical level. But unlike nucleons they have no intrinsic size as far as anyone can tell. -- BenRG (talk) 17:32, 9 January 2013 (UTC)
I'm not sure electrons have a "shape", per se. As far as I know, no one has ever demonstrated that they are anything but pure geometrical points (though of uncertain position). Whether the question even makes sense at all might depend on your interpretation of quantum mechanics.
However, if they do take up space, what shape should they be, except a sphere? Why prefer one direction over another? (They do have spin, so I suppose you could argue for some anisotropy based on the spin vector.) --Trovatore (talk) 09:25, 9 January 2013 (UTC)
P stands for (electrical) power, i.e. how much energy is used per unit of time (in Watt or J/s); Vc is simply the voltage over the capacitor. - Lindert (talk) 13:14, 9 January 2013 (UTC)
Where do you see "I" defined as a variable for current in the article? I did think exactly like you until I found it depended on other undefined variables. Electron9 (talk) 19:44, 9 January 2013 (UTC)
Yes, I was assuming standard symbols there. But also "Power = work per unit time", which seems consistent with the integral form. DMacks (talk) 19:52, 9 January 2013 (UTC)
Strength of gravity anomalies on earth
The image File:GRACE globe 1.png shows the differences in gravitational acceleration on different parts of Earth, after normalizing the differences caused by the rotation of earth and the polar radius being smaller than the equational radius. But the image doesn't include a legend for the colors, so I can't tell what the red and blue colors represent. So my question is, how large are these variations in the gravitational acceleration? – b_jonas11:23, 9 January 2013 (UTC)
PS. the image description links to . I tried to look there, but a quick look didn't give an answer. – b_jonas11:25, 9 January 2013 (UTC)
I have no idea why that was cropped out in the version you refer to!
The scale is in milligals - and the numbers range from -50 to +50, which is 50 thousandths of a 1 cm sec acceleration...normal gravity is around 9.8 m sec and these variations are at most -/+ 0.0005m sec - which is really very tiny! Note that gravity varies by a half percent between equator and pole - so what your latitude is matters vastly more than whether you're standing on a red spot or a blue spot on that map! SteveBaker (talk) 13:45, 9 January 2013 (UTC)
This site states that there is a 40 month prognosis with AL Amyliodosis, siting a British Medical Journal, without speaking to advanced symptomatic organ failure which accompanies most diagnosis. The actual prognosis of AL Amyliodosis with Cogestive Heart Failure (CHF) is 4-6 months. As it can take 4-6 months for a CHF patient to recieve the Amyliod diagnosis, siting a 40 month prognosis without additional information may lead patients and their families to adopt a wait and see posture early in the discovery process, thus leading to patient mortality. Perhaps someone would like to address this. — Preceding unsigned comment added by 71.232.106.77 (talk) 13:01, 9 January 2013 (UTC)
You really need to point this out and discuss it on the Talk:AL amyloidosis page where people discuss the content of that article. This is the reference desk - we answer questions and do information searches and such but we don't generally edit articles for people. Right now, I can tell you that the editors of that article are going to want to know where you got your information from. They need a reliable source that they can mention in the article...right now, they're going to say that the British Medical Journal is a highly respected source of medical information - and if it says 40 months - then that's the number they're going to put into the article unless there is another, more recent, reliable source that says otherwise. If you can point to a research paper or some kind of study document - then that will help them to get the article sorted out. But please discuss this on the talk page of AL amyloidosis - the reference desk is not the right place. SteveBaker (talk) 13:24, 9 January 2013 (UTC)
Because the rubric we learn for predicting the electron configurations is an approximation of reality, and reality is much more complex. --Jayron3214:08, 9 January 2013 (UTC)
A bit more: The Aufbau principle (aka Madelung's Rule) is a very rough approximation indeed, as it isn't really based on a rigorous mathematical understanding of the quantum mechanics of how electrons interact with the nucleus and with each other to produce a specific configuration. Instead, it is designed as a very rough "rule of thumb" that will get most people the right answer most of the time. There are other, more accurate, approximations , such as the Hartree–Fock method. So the answer is that the reason why copper, chromium, palladium (and indeed many other elements) don't directly obey the Aufbau principle is that the Aufbau principle is wrong, but it's right enough for first year chemistry students to get most elements correct. Indeed, for anyone that never gets to rigorous computational quantum mechanics, the Aufbua principle + memorize the exceptions is usually as far as they will ever get. --Jayron3214:22, 9 January 2013 (UTC)
Sorry. Aka is an abbreviation for "also known as". The answer to your question is that the method you were taught for determining electron configurations is wrong. Better methods exist, but they involve the sorts of mathematics that 99% of people (indeed, that the majority of chemists themselves) never learn. All methods are wrong (as the quote goes "All models are wrong, but some are useful"), but the one taught you in your chemistry class is more wrong than others. It's right enough, however, for the purposes of your chemistry class, and teaching you less wrong models would require taking several years to teach the mathematics first. --Jayron3215:24, 9 January 2013 (UTC)
Thank you Jayron, your second explanation was excellent. According to what have been taught in my chemistry class: In chromium second last shell and last shell contain 5 and 1 electrons respectively. On the other hand, second last shell and last shell of copper contain 10 and 1 electrons respectively. Is this true in reality ? Show your knowledge (talk) 15:49, 9 January 2013 (UTC)
Yes, that is really true. The electron configuration of every element can be determined spectroscopically, such that you can experimentally determine the actual configuration of electrons in an element. The "rules" you are taught in chemistry class (the Aufbau principle) whereby you add electrons to each element based on a simple formula, is mostly right, but it gets certain elements (like Chromium and Copper) wrong, insofar as the Aufbau principle predicts a configuration of 4s3d for chromium, but actual experiments have determined that the ground state configuration is actually 4s3d. There are models better than the Aufbau principle that closer match reality (i.e. models that actually predict the correct configuration of chromium and copper rather than explain them away as "exceptions" to the rule) but those models require a level of mathematics which is well beyond the average first year chemistry student. --Jayron3216:03, 9 January 2013 (UTC)
Why are all milk frothing mugs made out of stainless steel?
Does milk froth better in a stainless steel container than in a container made of another material (like ceramic)? If so, WHY does milk froth best in stainless steel? — Preceding unsigned comment added by Rmravicz (talk • contribs) 14:16, 9 January 2013 (UTC)
I assume that you are referring to coffee machines. My home one came with a plastic frothing jug, but I broke it, so now I use a Pyrex one. Both frothed equally as well as the stainless steel ones used in coffee shops. I suspect stainless steel is used, as it is easier to clean than glass or plastic and it won't break when dropped. I also think the professional jugs are doubled walled, so the Barista can froth enough milk for several cups and keep it hot. --TrogWoolley (talk) 15:24, 9 January 2013 (UTC)
Three questions
1) Why is oxygen necessary for survival? Why not other gaseous element?
2) What make our body to trap only oxygen when we breath in?
3? How long does it take to digest hen meat in our stomach? Sunny Singh 14:21, 9 January 2013 (UTC) — Preceding unsigned comment added by Sunnysinghthebaba (talk • contribs)
1) The reaction of oxygen with carbon based molecules creates a lot of energy, which we need for our organs and muscles to operate. There is no commonly available gas on this planet apart from oxygen that will perform this function.
2) Our blood vessels contain proteins (hemoglobin) designed to bond with oxygen, thus 'trapping' it, while leaving the nitrogen etc alone. However, they also bond with carbon dioxide and carbon monoxide, so that's why these gases are dangerous in significant concentrations because they take the place of oxygen and so deprive our organs of oxygen. - Lindert (talk) 14:37, 9 January 2013 (UTC)
(ec) 1) Because our bodies produce energy by combustion/respiration, which is an oxidation reaction, and thus requires oxygen. More generally, our biology is based on carbohydrates and proteins, both of which contain significant amounts of oxygen. Nitrogen is also needed, but N2 molecules are very hard to break - no regularly occurring substance burns in nitrogen - so we allow nitrogen-fixing plants (and the animals that eat them, unless we are vegans) to get hold of the nitrogen for us. The other atmospheric gases that come to mind are carbon dioxide, which is a product of respiration, and thus cannot be effectively used in such a reaction, and argon, which as a noble gas is almost (but not quite) impossible to react with anything.
2) The structure of haemoglobin in the blood allows for oxygen atoms to be attached; this takes place in the lungs (roughly speaking). It's not true that we trap only oxygen: for example, carbon monoxide poisoning takes place because the CO molecules bond more readily to the haemoglobin than the oxygen does, and won't come off.
3) As I recall, food (of whatever sort) doesn't stay in the stomach itself more than a couple of hours or so, but takes 24-36 hours to traverse the entire gastrointestinal tract. Digestion takes place throughout most of this period, by several methods. PS: in English, the meat of the hen is referred to as 'chicken'. AlexTiefling (talk) 14:43, 9 January 2013 (UTC)
(edit conflict) 1) Oxygen is involved in numerous biological processes, Dioxygen in biological reactions covers some of them. But basically, oxygen works by reacting with other molecules to release energy. You can see this dramatically in most combustion reactions, where the oxygen combines with things violently and rapidly to release huge amounts of heat very quickly. In biology, similar reactions are mediated by many enzymes which allow for a slow controlled release of energy that allows every other biological process to occur. 2) Oxygen is trapped from the air by hemoglobin, the specifics of which are covered in the Dioxygen in biological reactions article, in the "Oxygen uptake and transport" section. 3) Digestion#Human digestion process covers the specific timing of various parts of the human digestive process, including the amount of time food spends in the stomach. --Jayron3214:46, 9 January 2013 (UTC)
nanotube compressed air storage
So, nanotubes supposedly have such high tensile strength just a few molecules wide it can support a space elevator.
Anyhoo forget nanotubes. I'm not sure why I mentioned it. Imagine a sheet of zero weight and infinite tensile strength, and you make a container out of this. You are allowed to pump in air at a small differential to the atmosphere and some kind of mechanism gets it inside, and similarly you are allowed to get air out at the rate you want, magically. However, the container does not have further magical properties, and it is subject to normal laws of thermodynamics. We are just not concentrating on the tensile properties and the mechanism of letting you pump into it and out of it.
So, in this case, what is the limiting factor of how much air you could store in this for use as a mobile power source? Is it the weight of the air? Is it how hot the air inside would get? What happens if, for example, you put a million or a billion cubic feet of air inside?
Basically, I am trying to imagine what happens at the limit of a "perfect container" for storing compressed air.
Now let's turn to practicalities. Practically, what happens to the pressure as you put more and more air in? Where do current known materials have a theoretical limit on how much pressure they can hold? How does the weight of material needed increase in response to the amount of pressure you want? Does something special happen when so much air is put in that the pressure melts it? Freezes it? (What I mean, is would the pressure suddenly spike immensely when you put more air in once the air inside is already liquid, or already solid?)
Forgive me, I assume higher pressure compresses by first liquidizing then freezing the air. Please correct me if I'm wrong.
Now let's turn to the pump. What are the practical limitations on trying to create a pump that you can "easily" pump into and "practically" get power out of in non-explosive bursts, but rather a rate that is more appropriate for driving a car?
Basically, I am trying to imagine what would happen if a nuclear powerplant tried to load a container with several inches of nanotube sheeting with enough air to power a car for ten years. What /would/ happen?
Well before that, the material would be too heavy to transport. Are you saying that with the above assumptions ("infinite container strength and a really, really good pump") the package is already a lot better than gasoline? (Since we can simply stop once we've pumped enough energy into it for it to surpass the energy densitity of gasoline?) 178.48.114.143 (talk) 16:36, 9 January 2013 (UTC)
You might be interested in the articles Compressed-air vehicle and Compressed air energy storage. In practice, without cooling the container during compression, more and more of the pump energy will go to heat the compressed air (and hence the container, until it melts, or until all the energy of the pump is going into heating the atmosphere round the container). Using cooling, the compressed air can be converted into a pale blue liquid, and that's about as far as it is practical to go since most liquids are very difficult to compress further. Dbfirs17:33, 9 January 2013 (UTC)
Existing compressed-air cars use air stored at about 50Mpa of pressure and achieve about 1/20th of the energy density of gasoline (so 1/20th of the range for similarly sized "fuel" tanks). You might want to check out Orders of magnitude (pressure) to see what the effect of 1000Mpa pressure would be to get the same range as a gas-powered car. It's considerably higher than (for example) the pressures used to cut steel using high pressure water jets! Actually using that much pressure would be difficult because releasing a 1GPa air flow would destroy anything it hit! To get the pressure up enough to where it could store enough energy to run a car for a year, you're up at pressures where your carbon nanotubes would spontaneously form diamonds and your oxygen would turn into a metal!
For hydrogen this works and is near production. See . However, it depends on specific properties of the nanotube interacting with hydrogen to stabilize it - it's not just a tiny pressure tank, it actually sucks up the hydrogen, more or less. Wnt (talk) 19:46, 9 January 2013 (UTC)
What is the difference between anode rays and canal rays ?
Last paragraph of article Anode ray says As these perforations were named as canal so these rays are called canal rays. These are not the anode rays as these were not originated from the anode. The article doesn't clearly describes how these two rays are different. Please help ! Want to be Einstein (talk) 15:03, 9 January 2013 (UTC)
This terminology (and this technology) is not in common use in this century. So, it's really a matter of historical interest to quibble over the finer points of this terminology. Our article already links to a reprint of a 1913 article, Rays of positive electricity, published by J. J. Thomson; you can rest assured that he used his terminology consistently. As with all scientific jargon, different scientists have used different variations; but as of today (2013), not many people at all are actively publishing descriptions of these types of devices using that terminology. Most books and papers today will talk about charged ion beams or electron beams, and will talk about the positive and negative particles, or device terminals, (rather than the more confusing "anode" and "cathode" terminology). You'll still hear the term "Cathode Ray Tube" in common use, because those devices had such an important historical impact; but you won't be hearing about CRTs for very much longer, as almost every single use for vacuum-tubes - from display monitors to klystron microwave amplifiers to Bremsstrahlung x-ray sources - have all been replaced by better semiconductor or solid-state alternatives. Nimur (talk) 19:34, 9 January 2013 (UTC)
Every single use, Nimur? Not for a good while yet. To generate microwaves for cooking, at continuous power levels of several hundred watts, nothing beats a cavity magnetron, a type of cathode ray tube that is nothing more than a heated cathode surrounded by a shaped anode. Want to know what is the cheapest, most stable, easiest way to accurately (say 3- to 4-digit accuracy) measure voltages 30 kV and up? A triode valve (preferably a tungsten filament valve) - a type of cathode ray tube! You use the anode as the input, earth the grid, and vary the cathode voltage (typically 10 to 20 V or so) to get a specific cathode current (microamps or less), virtually none of which flows in the grid. The relationship of anode voltage to cathode voltage at a specific current is precisely linear within a good working range, dependent only on the tube physical geometry. The relationship to current is well understood (the "three halves power rule"). At lower voltages, or high voltages at lower accuracy, voltmeters normally use multiplier resistors. However, getting accurate stable resistors for 20 kV and up is not trivial - usually 2 digit accuracy is as good as you can get. There's also the old gold leaf electroscope, but they have woefull accuracy and are not linear. There's other niche applications for vacuum tubes/cathode ray tubes too. Keit 121.215.151.39 (talk) 23:44, 9 January 2013 (UTC)
Valid points. High-power solid-state devices are encroaching, but have not totally replaced tubes in some applications. By 2025, I suspect you'll even see microwave ovens using switch-mode IGBTs instead of cavity resonators. And I am not alone in this speculation: Power Electronics magazine published a technical article on 100 kW solid-state (IGBT) converters - so there's hardly any power- or frequency- regime that is "off-limits" for semiconductors. Pick up your favorite microwave or RF newsletter, and you'll see higher- and higher-power RF implemented in silicon. You are correct; the highest power systems haven't made the switch, yet. But it's a matter of time. Solid-state power is cheaper, safer, easier, better, more efficient, ... all the reasons that all other industry applications have switched to semiconductors. Nimur (talk) 00:09, 10 January 2013 (UTC)
You are certainly correct in saying vacuum tube technology is obsolete for most applications - that is very obvious. However niche applications for tubes continue. IGBT's are inherently low frequency devices and will not replace magnetrons. If you read the article about switch mode power conversion you linked to, you'll see they think 50 kHz is a good achievement. The triode valve method of measuring extra high voltages works well for short (microsecond) pulses too - nothing else does. Keit 124.178.60.57 (talk) 00:21, 10 January 2013 (UTC)
(Edit Conflict)
(Note: every technical explanation on the Internet must by law contain at least one glaring error that makes the writer look like an idiot...)
Start with a bunch of atoms in the form of a gas.
Cosmic rays and natural radioactivity knock electrons off, making (a few) ions - atoms that are missing an electron.
Apply a high voltage across the anode and cathode (typically made of metal)
High voltage accelerates ions toward the negative cathode.
Ions hit atoms in gas.
This knocks electrons off of atoms, making many more ions - a chain reaction
High voltage accelerates ions toward the negative cathode.
So we have ions traveling from the anode to the cathode - Anode rays.
Meanwhile the electrons travel from the cathode to the anode - Cathode rays.
(You can also get electrons from a heated cathode, but that's another story.)
In 1886 when Eugen Goldstein was first figuring this out, it was hard to look at the anode rays and cathode rays going past each other both ways and figure out which was which.
Goldstein put small perforations (canals) in the cathode.
Some of the ions in the anode rays passed though the canals.
Now he had a ray that was just the ions from the anode ray, with no electrons from the cathode ray to confuse the issue.
He called these rays that left the cathode in the opposite direction as the cathode rays (but only if the cathode had "canals") "Canal Rays" and the name stuck.
And yes, our article explains this poorly. Canal rays only appear to originate in the "canals". Then again, few engineers talk about "rays" or "cathodes" anymore. We talks about Electrons, Ions, negative terminals and positive terminals. Still, you see the old terms in a lot of the early papers from the scientists who discovered this stuff. --Guy Macon (talk) 19:53, 9 January 2013 (UTC)
"(Note: every technical explanation on the Internet must by law contain at least one glaring error that makes the writer look like an idiot...)" - the entire Reference desk system depends on this fact to keep us all interested! SteveBaker (talk) 20:16, 9 January 2013 (UTC)
Buoyant force
Suppose an object with flat base placed in a container containing water and container also has flat base. The object has rectangular shape and its density is lower than water. The object is submerged (by hand) into water in such a way that its base touches the base of the container. In that situation, there is almost no water below the object and also there is whole water of the container above object and the weight of this water column lies on the object. When the hand submerging the object is removed from water, the object comes on the surface of water as it has lower density than water. The question is:Why does object come on the surface even when there is no water below object to push it up and also the object is forced down by the weight of water column above it ? Does buoyant force depend on the amount of water present below an object ? I tried my best to explain where I got stuck, thank you for answering my question. Sunny Singh (DAV) (talk) 16:48, 9 January 2013 (UTC)
The pressure of the water is proportional to depth, and any air trapped below the object will exert the appropriate pressure under the object for that depth (being greater than the pressure on the top of the object at a lower depth). If you succeed in producing a seal round the edges of the base, and allow a tiny amount of flexibility so that the trapped air can expand, then the pressure under the object may well become lower than that on the top, so the object will not rise but "stick" to the bottom of the container. I think the same could happen to a very small quantity of water if inrush of water below the object is prevented. Dbfirs17:09, 9 January 2013 (UTC)
There is always going to be some water under the flat-bottomed object - you can't get a perfect contact between those two objects. But just do the thought-experiment of removing the water and just pushing the two objects together in air. If there was a perfect seal between the two objects, they'd be held together by the air pressure just like a suction cup on a sheet of glass! The deal in water is just the same. But if there is *any* gap, then water will intrude and because pressure in a liquid or gas exerts a force equally in all directions - there is nothing to prevent the object from floating away. SteveBaker (talk) 17:54, 9 January 2013 (UTC)
Aquaplaning or hydroplaning might be relevant. A very very tiny amount of water - just a few drops! - can be put into circumstances such that it has a very high dynamic pressure. In those cases, those few drops of water are sustaining the weight of an entire object above them - sometimes resulting in pressures equivalent to many thousands of PSI! That's enough to lift the entire weight of a heavy object - like a truck or a car or a four-hundred-ton cargo aircraft. This is a problem worthy of an entire NASA facility, the Aircraft Landing Dynamics Facility at NASA Langley. Here are some fun videos of this research: NASA Research on Hydroplaning. All this trouble comes from the fact that water is almost totally incompressible. Just a few drops of water will still occupy the same volume even if they are put under the crushing weight of thousands of atmospheres of pressure. Almost no water, if suitably constrained by a container, is therefore able to buoyantly lift a very very heavy object. Nimur (talk) 19:08, 9 January 2013 (UTC)
The same is, of course, true of the bottom of the very very heavy object. Ultimately there is only one layer of atoms at the bottom of anything, yet they hold it up. I think that SteveBaker's thought experiment works very well. Consider an object "stuck" to the bottom of a pool because there is a suction cup or other "vacuum" under it. What makes that a vacuum is that it is lower pressure relative to the water at the very bottom of the pool; in other words, we normally expect that pressure to propagate through perfectly. I suppose what amazes most is that physics is so good at "doing the math" - in other words, that if you have a narrow tube filled with atoms of water constantly moving about, that somehow the water at the near end and at the far end manage to come into such perfect agreement about what the pressure really is. The same amazement strikes people with other events, such as the ability to do DNA hybridization of a primer with a specific sequence out of an entire genome - as we see in that case, the computational power, though extraordinary, does have limits. Still, it is pretty amazing when you consider that the molecules doing the "math" by smashing together are moving only somewhere on the order of the speed of sound (I'm not entirely sure about the relation of this to the thermal speed according to the Boltzmann constant). Wnt (talk) 19:43, 9 January 2013 (UTC)
The point is that although they are only moving at the speed of sound, they are moving an incredibly short distance until they hit something and transfer the information. So the number of collisions per second is an ungodly high number - and that's how come this "calculation" happens so fast. SteveBaker (talk) 20:13, 9 January 2013 (UTC)
A related concept is Choked flow in a hydraulic or pneumatic system, where opening up a valve further downsteam has no effect on flow upsteam because there is a section of pipe with supersonic flow between them. It's the pneumatic/hydraulic equivelant of the speed of light; no information can travel faster than the speed of sound in the gas/liquid, so the upstream system doesn't "know" you opened the valve downstream. --Guy Macon (talk) 20:16, 9 January 2013 (UTC)
Butterfly flight
this is totally from left field, based on a single observation: a cabbagemoth butterfly was flying right to left - a stiff breeze arose, blowing in the opposite direction - but the butterfly continued unperturbed, whereas one would expect it to be blown away.
Possibly the air current wasn't wide enough to reach both me and the butterfly - but possibly it was. I thought back, and couldn't think of a time when I'd seen a butterfly blown off course. Has anyone here? Have they some as-yet-un-understood mechanism for beating the wind?
I think they just stay grounded during heavy winds. As you said, the wind current you observed must not have reached the butterfly. StuRat (talk) 23:09, 9 January 2013 (UTC)
Resolved
and 
stand for in the specified formulas? 
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