Content deleted Content added

Inline

Revision as of 20:40, 22 June 2014

Welcome to the science section
of the Wikipedia reference desk.

skip to bottom

Select a section:

Shortcut

WP:RD/S

Want a faster answer?

Main page: Help searching Wikipedia

How can I get my question answered?

Select the section of the desk that best fits the general topic of your question (see the navigation column to the right).
Post your question to only one section, providing a short header that gives the topic of your question.
Type '~~~~' (that is, four tilde characters) at the end – this signs and dates your contribution so we know who wrote what and when.
Don't post personal contact information – it will be removed. Any answers will be provided here.
Please be as specific as possible, and include all relevant context – the usefulness of answers may depend on the context.
Note:
- We don't answer (and may remove) questions that require medical diagnosis or legal advice.
- We don't answer requests for opinions, predictions or debate.
- We don't do your homework for you, though we'll help you past the stuck point.
- We don't conduct original research or provide a free source of ideas, but we'll help you find information you need.

Ready? Ask a new question!

How do I answer a question?

Main page: Wikipedia:Reference desk/Guidelines

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.

June 18

Contacting Google

Hi, so I have an idea that I would be interested in contacting Google (the corporate entity) with regards to. Obviously, everyone immediately thinks "crackpot inventor" who has some terrible invention that they think is amazing. Google obviously receives contact from people like this in the hundreds every day. What would be the best way to make someone with some semblance of decision making power aware of my idea? Email or post may not be an option as Google are famously un-contactable, however a social media campaign might work? Or contacting press to get notoriety? No legal advice please! 195.27.53.211 (talk) 10:01, 18 June 2014 (UTC)[reply]

Have you even tried? Obviously it has to be possible for people to contact them. There is a contact link here. I suggest you try that first.--Shantavira|^{feed me} 12:03, 18 June 2014 (UTC)[reply]

What is the idea? If you're considering using social media, then surely you could also tell us? My point is, if it matches up with some topic already being studied in Google's research labs, you might be able to contact that group directly. SemanticMantis (talk) 15:09, 18 June 2014 (UTC)[reply]

Many (perhaps most) tech companies go to some lengths to avoid even reading your suggestions! The reason for this is that they may be working on the same idea already - and if they talk to you about it - or even convey your message to those who create things - then you might be in a position to sue them for stealing your idea when it was really a case of parallel invention. In one company I worked for (a video game company), mail that came from unsolicited sources went to one specific staff member who would open it and dispose of anything that looked remotely like a suggestion for a new game or an improvement to an existing one. She never spoke to our engineers and other developers. We actively worked to AVOID taking suggestions from the public. I'm betting that Google are the same - they don't want your suggestions - they are just a pain in the butt to have to deal with!

So, if you have a world-beating idea, then work on it yourself - then run a Kickstarter project to raise some money to achieve it. SteveBaker (talk) 20:10, 18 June 2014 (UTC)[reply]

You may be right; I don't work at Google, or for a "tech" company (whatever that means :) But when I see people from e.g. Google Research or Microsoft Research at conferences, they are happy to present their work to us, and get feedback from their colleagues, etc. Of course, some of these people are more like academic research scientists than "normal" employees, so there is an expectation of sharing work via publishing, collaborating on projects across institutions, etc. SemanticMantis (talk) 20:54, 18 June 2014 (UTC)[reply]

A Google community relations manager (or somesuch) showed up at the Village Pump (if I remember right) when there were concerns about Google News changing in potentially negative ways. I think they had a Wikipedia account in order to make their comments. Someone like that might be a suitable contact. --Demiurge1000 (talk) 11:17, 22 June 2014 (UTC)[reply]

Silicon and the human body

This source says that there is no silicon in the human body. Is that accurate, or does it refer to the "living" parts only?

I.e. do the bones and/or teeth contain silicon? (The source doesn't look terribly reliable to me anyway. Lots of stupid little errors: "1026 watts" when it should read "10²⁶ watts" here, and even worse, H₂ when it should be H₂O here.) - ¡Ouch! (^{hurt me} / _{more pain}) 10:03, 18 June 2014 (UTC)[reply]

Composition of the human body does list a small amount of silicon. It has the unsourced claim that silicon is "probably needed by mammals also". -- Finlay McWalterᚠTalk 11:23, 18 June 2014 (UTC)[reply]

Well, there certainly will be some silicon in the digestive tract, although scientists consider this to be technically "outside" the body. Silicon dioxide is a common food additive: Silicon dioxide#Food and pharmaceutical applications. That's powdered quartz, BTW. StuRat (talk) 11:26, 18 June 2014 (UTC)[reply]

"Bartender, two quartz for Stu and me!" *COUGH*

Wow, thanks. I'd count that as outside, too. (Less than iron, too – I wouldn't have guessed that either!)

One more flaw of the source I was reading, I guess, not to mention the lines "Dimethyl borine (...) Soluble in organic solvents (ethanol, other[sic], etc.)" - ¡Ouch! (^{hurt me} / _{more pain}) 12:23, 18 June 2014 (UTC)[reply]

The answer is kind of hand-wavey. As near as I can tell, in humans it seems that silicon in various forms has some sort of beneficial effects on collagen and keratin(?) synthesis, but it's not clear that it is necessary. There is definitely evidence that it is present in the body, but it's not known if it is required. (See the footnotes for Silicon#Biological role, and Silicic acid#Silicic acid in health.) TenOfAllTrades(talk) 12:21, 18 June 2014 (UTC)[reply]

Disputed Identification

File:Artocarpus.odoratissimus1we.jpg

Tree with Disputed identification.

Any comments from the experts here? Sfan00 IMG (talk) 10:23, 18 June 2014 (UTC)[reply]

Any chance you know where in the world it was taken, or have any other photos of the leaves/flowers? I see the file is used at Artocarpus_odoratissimus, but the resolution is too low to even make out if the leaf margins are entire... SemanticMantis (talk) 15:07, 18 June 2014 (UTC)[reply]

It's sourced to a USGS image... I don't have much other information. :( Sfan00 IMG (talk) 18:03, 18 June 2014 (UTC)[reply]

Ok, who's disputing the ID, and where/why? I see a note on the file, but nothing on Talk:Artocarpus_odoratissimus. The source link on the file is broken, but I was able to re-find it here: [1]. Looks like these people are professional biologists, and have a ton of specific IDs for plants in Hawaii. The specific picture is tagged "Keanae Arboretum, Maui, August 07, 2003". Also, at the link above, we see there is a lot of variety in leaf shape of this species. So, together with the low resolution and the lack of specific reason to doubt, I'm inclined to use this as an expert ID and forget about it. SemanticMantis (talk) 19:48, 18 June 2014 (UTC)[reply]

What causes a radio to go off channel ?

I adjust a radio so the radio station comes in clearly, don't touch it after, yet the next day it is off station and needs to be readjusted. What causes this ? Is it temperature or humidity changes ? StuRat (talk) 11:19, 18 June 2014 (UTC)[reply]

Is it a digital, or analog control? IE, do you turn a knob to change the station, or press a button?Zzubnik (talk) 12:23, 18 June 2014 (UTC)[reply]

ObPersonal: having occasionally opened up old radios and radiograms to clean out decades of fluff accumulation, lubricate the parts, etc, I've noticed that some tuning mechanisms involve a length of cord between the tuner control wheel and the actual tuner. I assume that this might undergo slight changes of length due to both the factors you mention: tuning is often so sensitive that only a tiny change would have a noticeable effect, and my bathroom radio seems to require more retuning than most. {The poster formerly known as 87.81.230.195} 212.95.237.92 (talk) 13:52, 18 June 2014 (UTC)[reply]

(Not sure why you smalled your text, as this seems to be a direct answer.) Yes, it's an old analog clock radio. So, other than storing it in a hermetically sealed, temperature controlled vault, it sounds like there's no way to keep it on station. StuRat (talk) 17:49, 18 June 2014 (UTC)[reply]

That would have been a really cool magic trick back in the 50s or so. Have a cord with a good coefficient of thermal expansion near an ornamental hole where you could aim your breath into the radio. Ask the spirits to tune it in for you... if you could have done that without laying a hand on it, while your observers fail over and over again, even failing to see a reason after taking the radio apart... Wnt (talk) 16:54, 18 June 2014 (UTC)[reply]

OR It heats up, the dial expands, and moves off channel. μηδείς (talk) 20:23, 18 June 2014 (UTC)[reply]

Most good FM radios have AFC (Automatic frequency control) with sufficient range to compensate for temperature or humidity changes to tuning. AFC can however allow a strong signal to pull the tuning away from a weak signal when the signal frequencies are close. For this reason some receivers have an AFC on/off switch. 84.209.89.214 (talk) 22:40, 18 June 2014 (UTC)[reply]

Interesting, thanks. Would e.g. a late 1970s radio have AFC? Our article seems to indicate that similar functionality can be had via a Frequency_synthesizer, and that sometime in the 1970s consumer radio devices might have switched over. As far as other signals, that reminds me of an idea I had on the topic (for I have very similar experience to Stu): could changes in other signals cause a radio to fall out of tune? In a city, there are any number of sources of interference. Of course devices are supposed to both not produce interfering signals, and to accept incoming interference without malfunction, but I always took that to mean an ideal, which doesn't always happen in the real world. So, if my radio stays tuned to one station for weeks, but on a certain day I have to re-tune, and sometimes find that same station very difficult to receive. Could changes in other broadcasts explain this? SemanticMantis (talk) 22:54, 18 June 2014 (UTC)[reply]

All FM (but not AM) receivers are subject to Capture effect which is a kind of AFC, not a welcome one when interfering signals are strong. 84.209.89.214 (talk) 23:30, 18 June 2014 (UTC)[reply]

StuRat, if your radio's old enough, tuning is a function of the capacitance between two sets of metal plates, one of which is turned by the dial on the front or side of your radio. Since the plates are fan-shaped, turning one set varies the surface area of the sets of plates that are close enough to each other for capacitive coupling between the plates to occur, thus changing the frequency at which the tuning circuit resonates. If the plates aren't sealed (or very well-sealed) both atmospheric pressure and humidity can change from day to day and alter the capacitance between the sets of plates in your tuner, thus changing the target frequency. loupgarous (talk) 01:01, 21 June 2014 (UTC)[reply]

Thanks. Are new, but inexpensive, radios still subject to going off channel like this ? StuRat (talk) 05:33, 21 June 2014 (UTC)[reply]

Natural units

Look up Planck length and Planck time. If my knowledge about these terms is correct, these are units that we can't have a fraction of; every measurement of length/time is these units times a whole number. This is clearly very wrong, however, for Planck temperature. What property does the Planck temperature have here?? Georgia guy (talk) 16:01, 18 June 2014 (UTC)[reply]

I think your conceptual understanding about the quantization of time and distance is a bit incorrect: there's nothing that forbids a distance or length or duration whose magnitude is smaller than one Planck unit. We simply don't know of any physical entity or process in which that distance is meaningful.

On the whole, when a physical system is quantized it means that whenever we observe it, we will find integer multiples of some fundamental unit. There are lots of systems that are quantized, including macroscopic systems: for example, a theoretically perfect, tightly stretched guitar string will only resonate at integer multiples of its fundamental frequency. In practice, we know this is untrue: we hear musical timbre because of the interplay of all the complex harmonics and non-harmonic motions of the string and its soundboard.

In microscopic physics, we have the same problem! Electron orbitals are quantized, and when we look at an atomic emission spectrum, we find perfectly harmonic integer multiples of a base energy level. ...Except when we don't. Just like the guitar string, the major components of the system follow a simple, quantized theoretical model; but as we zoom in closer and closer to the details, we sometimes find perturbations and other effects. When we zoom in really closely, we usually find that those other perturbations are also quantized, but with different parameters. (In fact, we can say the same about the guitar - its continuous acoustic spectrum can be decomposed into a Fourier series of individual vibrations - and by definition, a series is made of discrete (quantized) elements).

One of the ongoing quests in theoretical physics is to find the most fundamental particles - and therefore, the most fundamental scale of quantization. A century ago, we split the atom into its subatomic particles; and we developed a rigorous theory for how the energies of those particles were quantized. Decades later, we split the subatomic particles into even smaller particles - quarks - and we found that they too have certain properties that are quantized. To my knowledge, we have not yet found any physical entity whose energy scales are quantized in smaller increments than these subatomic particles. That is why, in common parlance, we say that we have found the fundamental particles.

But we should make it abundantly clear: it is a physical system whose properties follow quantization rules: it is not actually the units themselves which are quantized. We can easily define half a Planck length - or a whole 1.0 Planck lengths, for that matter - even if we can't find any physical system for which that length is important.

Nimur (talk) 16:14, 18 June 2014 (UTC)[reply]

Atomic energy levels are nowhere close to integer multiples of a base energy level. Protons have three valence quarks, but they don't divide into three discrete pieces, one per valence quark. The notion of the quest for the most fundamental scale of quantization sounds more like Greek atoms than modern physics to me. -- BenRG (talk) 21:10, 18 June 2014 (UTC)[reply]

Fascinating analogy about Greek atomic theory! So fascinating that CERN, arguably the world's preeminent research institution in the field of modern particle physics, uses the exact same analogy when describing their quest to break apart sub-sub-atomic particles! Nimur (talk) 01:38, 19 June 2014 (UTC)[reply]

The sound of a guitar string can be quantified by a Fourier series whose infinite series of terms can be truncated not due to any property of the string vibration but because listeners are oblivious to harmonic and non-harmonic energies above the upper limit of human hearing. The quantisation step between Fourier terms is dictated by the frequency resolution obtainable from a given observation time, which is chosen arbitrarily. It is that arbitrary choice that changes the true continuous acoustic spectrum to an approximate discrete series. 84.209.89.214 (talk) 22:19, 18 June 2014 (UTC)[reply]

...and why do you think that's any different for atomic scale systems? I think you've just restated the uncertainty principle, which expresses the relation between the maximum achievable resolution in one variable, and extent of measurement in a second non-commuting variable. In this case, your variables are bandwidth, Δf, and duration-of-measurement, Δt. Fascinating how that applies in a classical problem, and we didn't even need to resort to literary gimmickry! Nimur (talk) 01:33, 19 June 2014 (UTC)[reply]

I think there is a big difference between Fourier's classical world view where math would allow no limit to the frequency resolution Δf obtainable by extending the duration-of-measurement T (using my symbol) and Heisenberg's discovery of a real-world impossibility of simultaneously knowing exact values of both position and momentum of a particle. That uncertainty cannot be overcome by making the observation longer, nor somehow less intrusive (as was thought) but has the reality of a physical constant. Having to accept tradeoffs between precisions of different quantities is routine to engineers in many fields but the quantum mechanical notion that the Universe itself cannot be entirely accurate is the Paradigm shift that unseated Lord Kelvin's famous assurance in 1900 "There is nothing new to be discovered in physics now. All that remains is more and more precise measurement." 84.209.89.214 (talk) 12:15, 19 June 2014 (UTC)[reply]

According to the article, the Planck temperature is a maximum possible temperature. So it seems as if the inverse temperature were more fundamental somehow. But is there a quantization of temperature into fractions of the Planck temperature? I know in general I've read some strange things about negative temperature that is hotter than any positive temperature, etc. ... but nothing gets colder than absolute zero. Is this system telling us that we're looking at the inverse of the quantity that really matters? And if so... what does it mean? Wnt (talk) 17:49, 18 June 2014 (UTC)[reply]

The Planck units are the unique unit system in which c = ħ = G = 1. That's literally all that we know about them. Naively you would expect important quantities in a theory of quantum gravity to have values close to 1 in those units (this is called naturalness, or just dimensional analysis). That doesn't mean the values would be exactly 1, or would be constrained to integers. If, by some other argument, you could show that quantum gravity implied quantization of, say, inverse temperature, then the quantum of inverse temperature would probably be small in Planck units. The Planck units by themselves don't tell you anything about minimum or maximum values or quantization. -- BenRG (talk) 20:24, 18 June 2014 (UTC)[reply]

Unless something has changed since I took math in high school, presuming that these units are numbers, they can be divided by any other number [except 0] or multiplied by any other number. ←Baseball Bugs ^{What's up, Doc?} carrots→ 20:55, 18 June 2014 (UTC)[reply]

Well, to quote the article directly then, As for most of Planck units, a Planck temperature of 1 (unity) is a fundamental limit of quantum theory, in combination with gravitation, as presently understood. In other words, the wavelength of an object can be calculated by its temperature. If an object was to reach the temperature of 1.41 x 1032 Kelvin (TP), the radiation it would emit would have a wavelength of 1.616 x 10-26 nanometers (Planck length), past which quantum gravitational effects are irrelevant. At temperatures greater than or equal to TP, current physical theory breaks down because we lack a theory of quantum gravity.[2] Now my understanding, I should add, is that a photon with a wavelength around the Planck length has a mass around the Planck mass and is, in short, a black hole. There's something really weird about this math... Wnt (talk) 21:09, 18 June 2014 (UTC)[reply]

Abuse of ignition interlock device

Sometimes a person convicted of a DWI will be required to install an ignition interlock device in their vehicle. From what I understand, the idea is to make the person blow into the machine, which then calculates their blood alcohol content (BAC). If they have an acceptable BAC, the vehicle will start. If their BAC is unacceptable, the ignition of the vehicle will not start. The objective is to prevent the individual from driving drunk or driving while impaired. So, my question is this. If an impaired person wants to drive – and wants to beat the system – they can just have some other individual, such as a non-impaired friend, blow into the machine. Is there some way that the machine itself or law enforcement prevents this from happening? In other words, how do "they" (the machine, the law enforcement and criminal justice system, etc.) know that it is the correct person who is actually blowing into the machine? Thanks. Joseph A. Spadaro (talk) 21:20, 18 June 2014 (UTC)[reply]

The answer is in the second paragraph of the BAC article: It requires an additional sample at some random point in time. Meanwhile, if a sober passenger not only allows a drunken driver to take the wheel, but also helps him try to evade the test, that passenger sounds like a candidate for a Darwin Award. ←Baseball Bugs ^{What's up, Doc?} carrots→ 21:41, 18 June 2014 (UTC)[reply]

The answer is in the second paragraph of the ignition interlock device article. 84.209.89.214 (talk) 22:26, 18 June 2014 (UTC)[reply]

Oops! Too bad I don't have a designated typer. ←Baseball Bugs ^{What's up, Doc?} carrots→ 22:40, 18 June 2014 (UTC)[reply]

As described by the article this device sounds rather rudimentary, though I suppose someone very drunk might have difficulties. It doesn't even describe a CO2 sensor, just a need for air to be pushed in. People on this forum seemed to think that any source of minorly compressed air would work. Wnt (talk) 23:37, 18 June 2014 (UTC)[reply]

Thanks. Not sure how I missed that. I skipped over the lead and went directly into the article, where I found nothing. Nonetheless, that is their method of trying to prevent the wrong person from breathing into the machine? Wow. The article says that the machine will require a second sample at some random time, later on down the road. That doesn't seem like that would be particularly effective. I would think that, oftentimes, drunk people are relatively close to home, not that far away in distance (i.e., at the local bar). Plus, I am sure most drunks are not thinking rationally. So, it seems to me that the drunk would easily convince himself that "Oh, I will just drive for a few minutes until I get home; the machine won't ask for a sample so soon; I'm sure I will be home by then". No? Or, not to mention, when the machine is asking for a second sample, just ask a new "clean" person who happens to be in the vicinity. No? Joseph A. Spadaro (talk) 01:26, 19 June 2014 (UTC)[reply]

Like a padlock, even though it's basic and easy to "beat" by force, it's effective in "discouraging" the behaviour and making it impossible to deny the "intention" to commit the crime of drunk driving. That second person would be responsible and perhaps held liable in a criminal and civil courts, not to mention endangering their own lives. The devices themselves are generally low-tech and can be defeated even without the aid of a second person. Virtually all ignition interlock devices and breathalyzers for that matter can be fooled with a baloon filled by the person before drinking. Some basic devices also lack a carbon dioxide sensor and can be beaten by forced air from any source. — Preceding unsigned comment added by 24.100.220.34 (talk) 04:49, 19 June 2014 (UTC)[reply]

The "second person" does not necessarily have to get in the car and go for a ride as a passenger (thus, foolishly risking his own life by being driven by a drunk). The "second person" can just blow into the machine, exit the car, and his job is done. I expect that would happen a lot with "friends" trying to "help each other out". Joseph A. Spadaro (talk) 18:17, 19 June 2014 (UTC)[reply]

I'm sure there are plenty of ways to evade the device - but consider that doing so results in a crime of far greater magnitude than DWI being committed - so if this hypothetical person were to get stopped (eg for driving erratically) then it would be clear that the device had been tampered with or misused - and I would expect them to incur a considerably greater punishment as a result. Remember, the purpose of the device is to allow them the privilege of driving (when sober) for the purposes of going to work or something. Without that device, they'd be barred from driving completely.

Yes, but all of that is based on the premise of the driver thinking and acting rationally (i.e., weighing the cost/benefit and the consequences). A drunk who just wants to get in the car and go home is probably not thinking so rationally. He is probably convincing himself that "I only live just a few miles down the road; I am sure I can get there just fine". Joseph A. Spadaro (talk) 18:12, 19 June 2014 (UTC)[reply]

OK, so the corollary to the popular saying would be, "Friends DO let friends drive drunk, as long as they won't be in the car." ←Baseball Bugs ^{What's up, Doc?} carrots→ 18:56, 19 June 2014 (UTC)[reply]

These days, I'm rather surprised that the devices aren't equipped with a camera. It would be easy to capture a short video of the driver taking the test - and if they were required to present that for inspection (say once a month) that would be an almost certain way to ensure that they aren't cheating the machine. SteveBaker (talk) 04:58, 19 June 2014 (UTC)[reply]

Maybe someday. Technologies evolve. Think of the evolution of the seat belt and the air bag, for example. ←Baseball Bugs ^{What's up, Doc?} carrots→ 06:52, 19 June 2014 (UTC)[reply]

I had the same thought, although a snapshot should be sufficient. A flash might be needed, though, as presumably many of these drunks get in their cars at closing time at the bar, when it will be dark out. The car dome light might be disabled by the drunk to hide the identity of the person taking the breathalyzer test. Disabling the camera flash or covering the lens would be more obvious tampering. You could also refuse to start the ignition unless a certain level of light is detected by the camera. StuRat (talk) 15:50, 20 June 2014 (UTC)[reply]

It's worth remembering that while wikipedia may have an article on anything, they aren't always that good. This FAQ from a manufacturer of such devices suggests that

1) Some do have cameras.

2) They do have anti circumvention measures which try and stop you using any random source of compressed air (I don't know how well they work obviously).

3) The random retest is apparently at least partially to discourage getting someone else to provide a breath sample. This is what the LEDE says and wasn't disputed above but if you look at the talk page, someone claims the "official reason" is to prevent a driver drinking while driving. (Perhaps also a driver who drunk very recently, but long enough that mouth alcohol has largely dissipated.)

4) Several minutes are provided to take the retest so you can pull over if necessary. I guess this will nominally allow someone to attempt to cheat again (theoretically there could be a much smaller time frame once the car has pulled over but this require the device to have access to data it probably doesn't). But I was thinking there must be such an allowance otherwise you may end up with a hazardous situation if a person has to try and take the test ASAP in unsuitable driving conditions. That said, per that source and [2] it sounds like the devices are designed so you can take the test while driving rather than having to pull over or wait until you stop naturally at an intersection or whatever.

I didn't see any mention of a flash there but if you mean an ordinary one, it seems a bad idea, at least for the tests while driving (and the source did suggest the retests are also recorded). A better proposition would be to use an infrared light or flash. You just need enough details that the person is recognisable after all. (You could probably find out what they use with more searching.)

Nil Einne (talk) 17:38, 20 June 2014 (UTC)[reply]

Thanks, all. Joseph A. Spadaro (talk) 18:39, 21 June 2014 (UTC)[reply]

June 19

Hair growth by weight

How many miligrams of hair (on the head, not including facial hair) does an average man with a full haid of hair grow in a month? Has this ever been measured empircally, rather than calculated? — Preceding unsigned comment added by 24.100.220.34 (talk) 04:39, 19 June 2014 (UTC)[reply]

L'Oreal did a calculation here that comes out to about .2 grams of hair per day or 6 grams per month. uhhlive (talk) 21:46, 19 June 2014 (UTC)[reply]

Geese and the transmission of information

Every spring (starting late May and early June) we get 100's of geese, mainly Canada goose, that congregate on both sides of the airport road (69°06′44″N 105°05′15″W / 69.11222°N 105.08750°W / 69.11222; -105.08750) where it is illegal to shoot them. At the same time there are thousands out of town. After a short period they move out onto the tundra to lay eggs and raise their young. Once the gosling's are born there might be one or two families that return to the sides of the road. You can drive by them with a truck or ATV and walk, even with a dog, by them and they don't move. The only way to get them to move is to walk towards them or bend over. However, the geese on the land (this is before the eggs are laid), where you can shoot them, will fly off well before you get into shotgun range. So the question is how do the geese know that being on the side of the road is safe? How do they transmit this information between one another? CBWeather, Talk, Seal meat for supper? 08:08, 19 June 2014 (UTC)[reply]

Good question. It's kind of the same question as "How do crows know to take off when the farmer walks out the door with his shotgun?" Perhaps it's experience - or lack thereof. ←Baseball Bugs ^{What's up, Doc?} carrots→ 09:43, 19 June 2014 (UTC)[reply]

I don't think it is possible to give any sort of precise answer, but there's little doubt that observational learning plays an important role. There are lots of well-studied examples of it in birds. See for example Observational learning#Social Learning in Crows. Looie496 (talk) 12:53, 19 June 2014 (UTC)[reply]

Crows do seem to be quite intelligent, and do seem to be able to communicate threats to each other. There was a study done where a person wearing a given mask harassed some crows, then later walked by a different group of crows, and they were frightened of him, too. So, somehow the first group communicated that he was a threat to the second group. There's also inter-species communication of threats. Of course a baking dog can communicate a threat to it's owner, but many other species cooperate and share intel like this. In some cases, the communication even describes the type of threat, like "snake". StuRat (talk) 15:59, 20 June 2014 (UTC)[reply]

Wait, isn't there a Canadian equivalent of the migratory bird act? I only ask because in USA it is illegal to ~~ever~~ shoot them in many circumstances... Our article says that UK acted "on behalf" of Canada in signing the treaty. Anyway, it's a little unclear from your description, but isn't there a timing difference as well? E.g. parents of young that cannot fly yet will be much less likely to take flight when threatened. Birds in general and fowl in particular behave very differently at different times of the breeding cycle (sorry, that article is terrible). Otherwise I agree with Looie's general comments and links. Finally, if you're interested in controlling them on your property, a pair of mute swans or a border collie usually does the trick. There are even service businesses in the US that come out with dogs and swans to keep geese away from golf courses [3]. SemanticMantis (talk) 14:42, 19 June 2014 (UTC)[reply]

Canada's version appears to be Migratory Birds Convention Act. According to [4], Canada geese are considered game birds and may be hunted in Canada under certain circumstances as game birds. Per various links like [5] and [6] it sounds like migratory Canada geese can generally be hunted in the US during certain seasons that are made on a year by year basis, and resident ones at additional times (when migratory ones are not really present and depending on the area). Nil Einne (talk) 16:10, 19 June 2014 (UTC)[reply]

Oops, thanks! SemanticMantis (talk) 16:57, 19 June 2014 (UTC)[reply]

Thanks for the replies. It looks as if Looie's links provide the answer. The parents molt at nesting time so they can't fly until the young are ready. That's why very few return to the road area before migration. They prefer lakes and large ponds where they can escape from foxes. The only problem we have with them is that besides the road they occupy the ponds at both ends of the runway. Thanks. CBWeather, Talk, Seal meat for supper? 09:43, 20 June 2014 (UTC)[reply]

For your specific example, here are some ways they could know the difference between areas where they might be shot and areas where they won't be:

1) Their own experience. If somebody shot at them or another bird in sight in one area, they will tend to think of that area as dangerous. This may not apply to other areas. Being migratory birds, they would need to understand that threats vary by location. For example, bears might be malnourished in one area and try to catch them, but may be well fed in another location and leave them alone for easier prey. Knowing this would be important to their survival. Also, they may remember a threat from previous years.

2) Another bird could communicate the threat level to them simply by flying away, or not, for a given stimulus. If all other birds fly away, they may do so too, even if they aren't directly aware of a threat. This can include birds of other species and non-birds that run away. A forest fire is a good example of this, when all species of animals can be seen flying and running away. I don't think they all directly detect the fire, but many just "go with the crowd" and follow where they are going. (Of course, this type of group behavior can lead to problems, too, like when one whale beaches itself and all the other whales follow it and beach themselves, too.)

3) Birds may also make warning calls telling others of the threat. This can include birds of other species and non-birds, too.

And a note on evolution here. While it wouldn't do a bird much good to understand the Theory of Relativity, knowing what is and isn't a threat is critical to their survival and thus passing down their genes, so a large portion of their rather limited brain capacity is devoted to this task. Therefore, they seem to be able to figure out threats in ways that require more intelligence than we credit them with possessing. StuRat (talk) 16:14, 20 June 2014 (UTC)[reply]

Synthesis of HgH
₂

What solvent would be useful for the titular synthesis, using dichloridomercury and lithium tetrahydridogallate, the temperature must be kept below 149 K (−124 °C; −191 °F)? Plasmic Physics (talk) 11:42, 19 June 2014 (UTC)[reply]

Ethereal solvents are commonly used for metal-hydride reactions, but I don't know specifically about gallates. Diethyl ether melts at 157 °C, so having some reactants/products dissolved it it (or adding a small amount of some other cosolvent) would probably drop the mp 8 K or or more, enough to keep it liquid at your target temperature. Dimethyl ether would be a liquid at that temperature range, but you'd have to condense it to use it...a practical annoyance. If you don't need an ether, alkanes C5 and smaller have low enough mp. DMacks (talk) 18:08, 19 June 2014 (UTC)[reply]

Erm, you mean 157 K! Wnt (talk) 22:32, 19 June 2014 (UTC)[reply]

I don't think that alkanes are good solvents for salts (lithium tetrahydridogallanate), or is this particular salt an exception to rule? Plasmic Physics (talk) 03:25, 20 June 2014 (UTC)[reply]

Why in God's name would you want to make mercury(II) hydride in the first place? TenOfAllTrades(talk) 18:04, 19 June 2014 (UTC)[reply]

As the article states, it has no economic uses, and is made only as an academic curiosity. Like all mercury compounds, it is toxic. If you aren't a chemistry professor planning to publish a paper for research, it is best avoided. (If you were a chemistry professor, you probably wouldn't ask here because you would have done a literature search.) Robert McClenon (talk) 18:09, 19 June 2014 (UTC)[reply]

As a starting point, one would have found a ref for using lithium gallanate in this type of reaction it and start with that solvent. DMacks (talk) 18:18, 19 June 2014 (UTC)[reply]

No need for him to apologize for curiosity - it is indeed interesting to find out about solvents that are good for crazy cryogenic reactions! Wnt (talk) 22:32, 19 June 2014 (UTC)[reply]

It is probably toxic, but since it rapidly decomposes above 149 K, the only likely hazard is by contact, and even then, cryogenic burns are the biggest issue. Plasmic Physics (talk) 00:19, 20 June 2014 (UTC)[reply]

Well, I thought since this compound has been identified for a while, it is about time that it is isolated also. So, I'm just working through a method to see how it could be done. Plasmic Physics (talk) 00:02, 20 June 2014 (UTC)[reply]

One of the refs in the article (the one that discusses the magic temperature of decomposition) mentions making it and isolating it on a cold plate. Heck, they make it at what, 4 K, and then warm it enough to remove the unreacted reactants, matrix, etc. DMacks (talk) 02:23, 20 June 2014 (UTC)[reply]

That is not what I meant. I meant a reaction which is not photocatalytic. Plasmic Physics (talk) 03:25, 20 June 2014 (UTC)[reply]

How well can temperature be controlled in cryogenic syntheses? Plasmic Physics (talk) 00:02, 20 June 2014 (UTC)[reply]

Very well on small scale. Baths can easily be controlled to a degree or tenth or even better at some ranges. But getting that equilibrated throughout a reaction medium becomes harder as scale increases as the reaction becomes more exothermic. Endothermic often less of a problem because "a bit too cold" for an already very cold reaction just means the reaction slows down until the temperature re-rises to match bath (negative feedback that does not usually damage the product, etc.) See Cryocooler and Cooling bath (I remember being surprised at first how predictable those were once I managed to avoid freezing them outright). Or can just use a liquid+solid bath of some material whose melting point is the temp you want. DMacks (talk) 02:20, 20 June 2014 (UTC)[reply]

Parallel plate transmission line

I looked in the transmission line article but it does not describe this version. I want to know if parallel plate transmission lines are always balanced, or can they be operated unbalanced?--86.180.143.223 (talk) 17:33, 19 June 2014 (UTC)[reply]

A Microstrip line consisting of a thin flat conductor which is parallel to a ground plane is an example of an unbalanced parallel plate transmission line. One can model a balanced parallel plate transmission line as two microstrip lines back-to-back with a common ground plane that can be removed since, by symmetry, it carries no current. 84.209.89.214 (talk) 19:55, 19 June 2014 (UTC)[reply]

I should have made it clear that what I meant by a parallel plate transmission line is one where the conductors each have the same width. This is therefore different from the microstrip arrangement which is operated in unbalaced mode. Is there any advantage to a symmetrical parallel plate line being operated balanced or unbalanced? --86.180.143.223 (talk) 11:11, 20 June 2014 (UTC)[reply]

The unbalanced parallel plate line is not as well isolated from the surroundings as when balanced, since its fields do not cancel at a distance. Therefore unbalanced lines are more susceptible to interference or to causing interference...unless you wrap the ground plane around to change the line to a Coaxial cable. Balanced lines are easy to set up for a desired impedance, such as when matching to a Dipole antenna. See Dipole antenna#Feeding a dipole antenna. 84.209.89.214 (talk) 19:14, 20 June 2014 (UTC)[reply]

Wheat in Stilton

Our article on Stilton cheese makes no mention of its wheat content, but it's an allegation -- for want of a better term -- that's consistently made online. Could anyone point me in the direction of a WP:RS that states that Stilton contains wheat so that I can add it to the article (or not, as the case may be)? I don't eat wheat but used to be damned fond of a tasty piece of Stilton and would like to be sure one way or another. Thanks, Ericoides (talk) 18:25, 19 June 2014 (UTC)[reply]

Hope this article and the links contained therein helps you make your mind up. --TammyMoet (talk) 18:32, 19 June 2014 (UTC)[reply]

Thanks very much for that, interesting. I was looking more for a book or journal article on Stilton rather than web/blog links. The material also seems rather US-centric, not much on Stilton per se. But thanks again. Ericoides (talk) 18:55, 22 June 2014 (UTC)[reply]

Islands with largest highest-point-to-area ratio

I'm interested making relief maps of islands with large highest points relative to their area, so that they look more interesting. Taking islands over 10000 km² in area from List of islands by area and over 2000 m high from List of islands by highest point, I compiled this list:

Island	Highest point (m)	Area (km²)	Ratio (m/km²)
Hawaii	4205	10434	0.403
Mindoro	2582	10572	0.244
Jamaica	2256	11190	0.202
Sumbawa	2722	14386	0.189
Negros	2435	13074	0.186
Panay	2117	12011	0.176
Seram	3027	17454	0.173
Palawan Island	2085	12189	0.171
Flores	2370	14154	0.167
Sicily	3326	25662	0.130
Taiwan	3952	35883	0.110
Timor	2963	28418	0.104
Vancouver Island	2195	31285	0.070
New Britain	2334	35145	0.066
Alexander Island	2987	49070	0.061
Axel Heiberg Island	2210	43178	0.051
Hispaniola	3098	76480	0.041
Sri Lanka	2524	65268	0.039
Mindanao	2954	97530	0.030
Hokkaido	2290	78719	0.029
Luzon	2922	109965	0.027
Java	3676	138794	0.026
South Island	3724	145836	0.026
North Island	2797	111583	0.025
Iceland	2110	101826	0.021
Sulawesi	3478	180681	0.019
Honshu	3776	225800	0.017
Ellesmere Island	2616	196236	0.013
Sumatra	3805	473481	0.008
New Guinea	4884	785753	0.006
Borneo	4095	748168	0.005
Madagascar	2876	587713	0.005
Baffin Island	2147	507451	0.004
Greenland	3694	2130800	0.002

However, Penang Island, at 833 km² and 295 m has a ratio of 2.824, much larger than any of the above.

Is there a quick way of get a list of islands with the largest ratios?

Thanks! cmɢʟee⎆τaʟκ 19:25, 19 June 2014 (UTC)[reply]

Can't help with a general list, but I bet Ball's_Pyramid has a high ratio. It made some news recently when this critter Dryococelus_australis was recently re-discovered there. Stack_(geology) will have some other very tall "islands" with small areas. Also, your ratio is effectively getting at rugosity, though that ratio is unitless, while yours comes out to the slightly-weird 1/m. SemanticMantis (talk) 20:18, 19 June 2014 (UTC)[reply]

The smaller the islands in your list are, the bigger the numbers you will get, so for a 1 km² island peaking at 1m you will get 1.0, but really that is not very impressive at all. You should use something more like a height to width ratio. Graeme Bartlett (talk) 21:13, 19 June 2014 (UTC)[reply]

Good point. Rugosity is similarly not biased by area. But computing rugosity for an island probably can't be done without very good topographic maps or lidar imaging (and some decent effort on top of that). SemanticMantis (talk) 21:29, 19 June 2014 (UTC)[reply]

Try height divided by the square root of area. It's dimensionless and doesn't depend on the island being round or long. Oh, and do compute it for SemanticMantis' example, and for the Old Man of Hoy. AlexTiefling (talk) 21:35, 19 June 2014 (UTC)[reply]

(ec) Exactly. To some approximation, you will have the steepest average slope from shoreline to peak on the island with the greatest ratio of highest point to 'width'. Of course, since islands aren't necessarily square or circular, that concept of 'width' is a bit fuzzy. For a 'scale' term, you could just use the square root of area, and take the ratio of height to that scale length to get a 'steepness' score. (Incidentally, Hawaii tops that list too. Penang Island, meanwhile, ends up around the middle of the new list.) TenOfAllTrades(talk) 21:39, 19 June 2014 (UTC)[reply]

Many thanks, SemanticMantis, Graeme, Alex and TenOfAllTrades. You're right, this gives prominence (mind the pun!) to small islands. Perhaps even more extreme than Ball's Pyramid is Ko Tapu, assuming its area is a circle of 4m diameter at sea level. I couldn't find the area of Old Man of Hoy, but estimate a width of 35 m from photos. Dividing by square root of area gave:

Island	Highest point (m)	Area (km²)	m/√km²
Ko Tapu	20	0.000016	5000
Old Man of Hoy	137	0.01	1370
Penang Island	833	295	48
Hawaii	4205	10434	41
Mindoro	2582	10572	25
Seram	3027	17454	23
Sumbawa	2722	14386	23
Jamaica	2256	11190	21
Negros	2435	13074	21
Taiwan	3952	35883	21
Sicily	3326	25662	21
Flores	2370	14154	20
Panay	2117	12011	19
Palawan Island	2085	12189	19
Timor	2963	28418	18
Alexander Island	2987	49070	13
New Britain	2334	35145	12
Vancouver Island	2195	31285	12
Hispaniola	3098	76480	11
Axel Heiberg Island	2210	43178	11
Sri Lanka	2524	65268	10
Java	3676	138794	10
South Island	3724	145836	10
Mindanao	2954	97530	9
Luzon	2922	109965	9
North Island	2797	111583	8
Sulawesi	3478	180681	8
Hokkaido	2290	78719	8
Honshu	3776	225800	8
Iceland	2110	101826	7
Ellesmere Island	2616	196236	6
Sumatra	3805	473481	6
New Guinea	4884	785753	6
Borneo	4095	748168	5
Madagascar	2876	587713	4
Baffin Island	2147	507451	3
Greenland	3694	2130800	3

(For comparison, Burj Khalifa at 830 m and 0.008 km² has a value of 9300 and the Dushanbe Flagpole at 165 m and 0.00002 km² (estimate) has a value of 37000!)

Guess the problem now becomes subjective, as to how small an island to accept while it still being relatively well-known. Thanks for all your help! cmɢʟee⎆τaʟκ 13:15, 20 June 2014 (UTC)[reply]

If anyone's curious, approximating the basal area of Ball's Pyramid by an ellipse, we get an area of ~1.036 km^2. This gives the ratio as 563m/√(1.036)km² ~= 552, making it third on the list above. Also I think the arithmetic on Ko Tapu is wrong. For a 4m diameter I get area= 4pi m2=1.25664e-5 km^2. Then 20m/√(1.25664e-5)km² ~= 5642. Using the top diameter of 8m I get a ratio of ~2821. So barring any other arithmetic errors, Ko Tapu is the clear 'winner'! SemanticMantis (talk) 15:37, 20 June 2014 (UTC)[reply]

Carbonatite magma phase separation

Carbonatite lavas are very unusual in appearance and composition, and apparently result from the separation of phases in magma. See [7] for some video well worth watching. A question they raise in my mind, though: does the separation of phases here have anything to do with the hydrophilic aqueous phase and hydrophobic organic phase that typically dominate a smaller and cooler separatory funnel than the ones here delivering different flavors of magma to the Earth's surface over spans of (only) thousands of years? Does the partition of various minerals to these phases align with an analysis of how polar they are expected to be in a magma setting? Can you say that a carbonatite or silicate phase mixes with X mixes with Y mixes with... until you have a series that relates it in hypothetical miscibility directly to oil or water? If not, can you find a direct analogy from liquids at STP for this kind of phase separation? Wnt (talk) 22:40, 19 June 2014 (UTC)[reply]

WE have an article on this volcano, Ol Doinyo Lengai. μηδείς (talk) 17:27, 21 June 2014 (UTC)[reply]

In magma, hydrophilic/hydrophobic properties are irrelevant because the system does not include liquid water (only water vapor, if any); a more relevant classification is into lithophile, chalcophile and siderophile minerals (which has more to do with electronegativity and ~~polarisibility~~ polarisability, not dipole moment). That said, since the elements found in carbonatites are extreme lithophiles, this kind of differentiation may indeed take place (although there are other hypotheses as well). Bottom line is, we don't know enough yet to tell for sure. 24.5.122.13 (talk) 00:40, 20 June 2014 (UTC)[reply]

Perhaps there should be a redirect: polarisibility → Polarizability 71.20.250.51 (talk) 03:19, 20 June 2014 (UTC)[reply]

polarisability?

In any case, how can things be separated based on electronegativity? I thought things with different electronegativity tend to like each other, like sodium and chloride?

As for polarisability, is that more important in magma because so many ions are present in that environment, or some other reason? Is there any example of phase separation on this basis at STP?

Oh, also: under Goldschmidt classification all the rare earths are listed as "lithophiles". But the article I linked at top says that the only rare earth mines are in these abnormal carbonatite deposits... Wnt (talk) 05:43, 20 June 2014 (UTC)[reply]

OK, one thing at a time:

(1) Thanks for correcting my spelling -- that's precisely what I meant.

(2) In magma, precisely such a separation is believed to take place: siderophile (electronegative) cations remain in their reduced (metallic) state, chalcophile (electropositive, polarizable) cations combine with sulfur anions (one of the two major anions in magma) to form sulfides, and lithophile (electropositive, non-polarizable) cations combine with oxygen anions (the other major anion) to form oxides (which may react further to form hydroxides or carbonates).

(3) In magma, polarisability is important because oxygen and sulfur are the major anions, and polarisability determines a cation's affinity to each -- high polarisability will favor combining with sulfur (which is also polarizable), and low polarisability will favor combining with oxygen (which is also nearly non-polarizable).

(4) The carbonatite deposits preferentially include lithophilic minerals, and exclude siderophilic and chalcophilic minerals -- so there's no contradiction re. rare earths. 24.5.122.13 (talk) 07:50, 20 June 2014 (UTC)[reply]

Thanks! You're being very helpful. I hope you'll consider starting an account and contributing to our articles.

Come to think of it, would a mixture of metallic mercury and carbon tetrachloride provide an example of this sort of phase separation? Wnt (talk) 14:03, 20 June 2014 (UTC)[reply]

Perhaps, if they're mixed and then allowed to stand for a few days (or maybe a couple weeks or more). Why don't you try and see? (I don't need to remind you to do it in a well-ventilated area -- both substances give off toxic vapors.) 24.5.122.13 (talk) 06:02, 21 June 2014 (UTC)[reply]

June 20

Attraction between charged object and stream of water - does it really show that water molecules are polar?

I have seen in several places (such as on this webpage: [8] ) that the deflection of a stream of water towards a charged object shows that water molecules are polar. Does it really show this? I have managed to find an example of a stream of liquid NOT being attracted to a charged rod ("Nonpolar tetrachloromethane molecules are not attracted to either charged rod." [9] ). This still does really show the reason why water IS attracted (and is not due to something like charges on surface, or conductivity of water, for example). FrankSier (talk) 15:26, 20 June 2014 (UTC)[reply]

I don't know the answer to your question - but the business of attracting (or not) flows towards nearby objects doesn't necessarily indicate polarization - it can also happen due to the Coandă effect and also to Bernoulli's principle...so it's not always easy to determine which effect is in play. SteveBaker (talk) 19:14, 20 June 2014 (UTC)[reply]

I think the OP is asking about a situation where the stream of liquid isn't actually touching the charged object, so fluid dynamics effects aren't really an important part of the problem. Red Act (talk) 20:26, 20 June 2014 (UTC)[reply]

You are correct, the deflection of a stream of liquid towards a nearby charged object is not a sufficient condition to conclude that the liquid is composed of polar molecules. For example, a stream of mercury will be deflected towards a nearby charged object because it conducts and hence can develop a nonzero free charge density, not because it develops a nonzero bound surface charge density due to the alignment of electric dipoles as in the case of a stream of pure water. Red Act (talk) 20:13, 20 June 2014 (UTC)[reply]

Also, carbon tetrachloride may just be not polarizable for a demonstratable effect. A longer-chained hydrocarbon may show more pronounced london dispersion forces than CCl4 even if it is non-polar. --Jayron32 02:27, 21 June 2014 (UTC)[reply]

The refractive index of carbon tetrachloride is not exactly 1 (article says n=1.4607), therefore the Lorentz–Lorenz equation gives a noticeably non-zero polarizability. DMacks (talk) 17:24, 21 June 2014 (UTC)[reply]

Isn't it true that the fact the water molecules are polarized has been established with X-ray crystallography? --AboutFace 22 (talk) 01:58, 22 June 2014 (UTC)[reply]

I'm sure that that is but one of the MANY pieces of evidence that water is a polar molecule. There's uncountable pieces of such evidence; no one "proves" the "fact" any more than any of the others, instead the entirety of the evidence is consistent with the idea that water is polar. Science does not provide "proof" of "facts", instead, science provides evidence which is consistent with some model, law, theory, or principle. The more evidence in support of an idea, then the more likely it is the idea is sound. But there is no one single "EUREKA" bit of evidence which conclusively "proves" an idea as a "fact". --Jayron32 20:22, 22 June 2014 (UTC)[reply]

The gray circle for microwave toasting

Things like microwaveable pot pies that have a gray circle on the interior of the packaging that help to toast the product- what is that material? It must not be very metallic, otherwise sparks would fly. What is it?20.137.2.50 (talk) 16:22, 20 June 2014 (UTC)[reply]

I think it is metallic, but the metal bits are small and disconnected, so they don't get a chance to build up enough of a charge to arc. StuRat (talk) 16:24, 20 June 2014 (UTC)[reply]

Our article on susceptors have a bit more details - in short it's a material able to absorb electromagnetic energy and convert it to heat. WegianWarrior (talk) 16:43, 20 June 2014 (UTC)[reply]

Name of foot ailment.

(This isn't a request for diagnosis, prognosis or treatment advice for any medical condition)

I'm trying to find the name - and prevalence in the USA - of a medical condition whereby standing for too long (possibly for occupational reasons) can cause nerve damage - which in turn can result in some kind of postural problem - which goes unnoticed because of the nerve damage - ultimately result in a foot condition so bad that it may require amputation. That's basically all I know about it - I'm really just trying to find some hooks for information so I can go read up about it myself.

(There are days when I'm actually glad that I have a desk job!)

TIA SteveBaker (talk) 19:22, 20 June 2014 (UTC)[reply]

I don't think there is a separate foot related disease like this. What you are describing vaguely resembles peripheral neuropathy typically as a consequence of diabetes type II. Being overweight helps also. Vasculitis also may be a contributing factor. --AboutFace 22 (talk) 20:02, 20 June 2014 (UTC)[reply]

BTW, what nerve damage do you have in mind? Afferent, sensory nerves or efferent, motor nerves? --AboutFace 22 (talk) 20:07, 20 June 2014 (UTC)[reply]

I don't know! That's what I'm trying to find out. I'm guessing that because (I'm told) the nerve damage causes sufferers not to notice that they're somehow making matters worse - that it's probably sensor nerves that are the problem here. But I honestly don't know. SteveBaker (talk) 21:15, 20 June 2014 (UTC)[reply]

The context here is that someone wants to have me work on a gadget to help these people - and before I first go to talk to the guy, I'd like to try to appear at least a little fluent with the science - maybe know some of the words. SteveBaker (talk) 21:15, 20 June 2014 (UTC)[reply]

Steve, we have a (terribly sourced) article Long-term complications of standing, but it doesn't mention anything about nerve damage. Deor (talk) 20:43, 20 June 2014 (UTC)[reply]

Hmmm - didn't seem to illuminate much...thanks for trying. SteveBaker (talk) 21:15, 20 June 2014 (UTC)[reply]

You may be thinking of peripheral neuropathy. Standing too long on hard surfaces (e.g. concrete) can trap the sciatic nerve which can lead to neuropathy in the feet. The loss of sensation in the feet can lead to many complications, as evidenced by the number of diabetics who have it and the resulting huge number of amputations: according to one source, over half of all non-traumatic amputations in the US are caused by complications of diabetes mellitus/peripheral neuropathy.

The only other thing I can think of is plantar fasciitis. Standing too long is a risk factor for the condition, and certainly it aggravates the condition if already present. It can cause posture issues due to changing the way one walks because of the pain in the heels. What doesn't fit is the ultimate amputation - if methods such as cortisone injections don't address the problem, people with plantar fasciitis may have surgery. I suppose most surgery carries with it some possibility of nerve damage, but that would be an extremely rare event in this case (as far as I know). Julia\^talk 21:38, 20 June 2014 (UTC)[reply]

Thanks! I think that your description of peripheral neuropathy is closest to the mark...although our article on that subject didn't throw much light on the problem. I have gotten plantar faschiitis myself and it hurts like hell when you first stand up - but the pain goes away after a few minutes. My doctor didn't suggest any significant complications from it and a switch from wearing sandals to trainers (along with a $7 course of Meloxicam) fixed it up without problems - so it really doesn't seem to fit the description here.

The idea that so many amputations are caused by this condition perfectly fits what I've been told. Maybe the detail about this being mostly a problem for diabetics got left out of the very vague description that I was given.

I also suspect that a large part of the problem here (in the USA) is that the people suffering from this may not have health insurance - so the problem may get ignored for too long - preventative measures may not be taken in time and surgery may simply be too expensive. If these people also tend to ignore the doctors' advice on how to stand and keep moving (or whatever it is) - then you could easily see how it could get out of control and be the cause of all of those amputations.

Anyway, I feel a little better informed and can sound at least a little educated when I come to discuss it. Thanks! SteveBaker (talk) 14:31, 21 June 2014 (UTC)[reply]

There are many occupations where people spend their work days on the feet. Pharmacists is an example. Actually sitting behind your desk all day is unhealthy. You are not really blessed, you are cursed :-) There have been articles recently in the medical press. Standing up is much healthier if you are of a normal weight. Plantar fasciitis may be a connective tissue problem, not occupational. People with peripheral neuropathy often have other liabilities including cognitive and they can miss the onset of the problem. --AboutFace 22 (talk) 01:45, 21 June 2014 (UTC)[reply]

That's what I understand (see my post, above). (And, yes, I know that sitting behind a desk - as I mostly do - is bad!) SteveBaker (talk) 14:31, 21 June 2014 (UTC)[reply]

Standing and moving around may be healthier than sitting, but standing in one position isn't. We're not built for that. StuRat (talk) 02:34, 21 June 2014 (UTC)[reply]

Yeah - and I'm pretty sure that's the problem here. SteveBaker (talk) 14:31, 21 June 2014 (UTC)[reply]

I'm thinking aloud here and I have to go out shortly so I don't have the time to research this properly, but someone else might. Firstly, it is possible that standing for long periods of time might result in flat feet, but I don't see how that can ultimately lead to amputation. What might is a vascular problem though, in which the venal valves aren't capable of properly moving the blood upwards so the blood pools in the lower legs and feet. Varicose veins are one manifestation of this, possibly also stasis dermatitis. Possibly also a thrombosis. Apparently it's why policemen bend their legs at the knees, to encourage the blood to move upwards. (Gosh it's 30 years since I learnt this stuff and I guess that things may have changed since then!) --TammyMoet (talk) 09:07, 21 June 2014 (UTC)[reply]

Interesting...thanks! SteveBaker (talk) 14:31, 21 June 2014 (UTC)[reply]

June 21

Has anybody ever seen an overweight redhead?

question asked and sufficiently answered

The following discussion has been closed. Please do not modify it.

Yep, this is my question. --AboutFace 22 (talk) 01:48, 21 June 2014 (UTC)[reply]

Here's one: [10]. Here's another: [11]. :-) StuRat (talk) 01:59, 21 June 2014 (UTC)[reply]

I don't think we need anymore of this. We have enough of an answer.--Jayron32 02:04, 21 June 2014 (UTC)[reply]

Movie stunt

In Goldeneye, when James Bond rides a motorbike off a cliff, how does he catch up to the plane? I mean, he's in freefall, but so is the plane -- AND the plane's engine thrust is also adding to its acceleration. So according to the laws of physics, the plane would either hold its lead, or more likely even pull further ahead -- right? 24.5.122.13 (talk) 02:21, 21 June 2014 (UTC)[reply]

See fiction and come back if there is something there if you don't understand. --Jayron32 02:25, 21 June 2014 (UTC)[reply]

Don't bite the newbies. It's perfectly valid to ask if science portrayed in a movie is realistic or not. That's what we're here for. If you don't like such Q's, don't reply to them. StuRat (talk) 02:31, 21 June 2014 (UTC) [reply]

With respect StuRat this poster is not a newbie and the framing of his question indicates s/he understands the impossibility of the situation. Richard Avery (talk) 07:31, 21 June 2014 (UTC) [reply]

Yes, and a motorcycle and rider are less aerodynamic than a plane, so you would expect them to be slowed down even more, due to air resistance. StuRat (talk) 02:27, 21 June 2014 (UTC)[reply]

Bond films tend to rely heavily on suspension of disbelief; in other words, "just sit back and enjoy the show —and don't think about it too much".

—71.20.250.51 (talk) 04:42, 21 June 2014 (UTC)[reply]

Well, if we do want to analyze it, it's actually rather complicated. First, the motorbike is in free fall and would follow a parabolic trajectory if air resistance (friction) was not significant, but the force of friction will act diagonally in the opposite direction to its motion, i.e. horizontally backward at first, but also upward as it begins to fall.

But as to the plane, it's not in free fall: it has wings. Normally the lift would be in an upward direction to counter the plane's weight, but if I remember the scene correctly, the plane tilts nose-down as soon as it goes off the cliff. This means that the lift will also be exerted diagonally, upward and somewhat forward. Like the motorbike, the plane experiences air resistance (friction or drag in a diagonal direction opposite its movement, i.e. upward and backward, since it's diving nose-down; but the engine's force is in the opposite direction, forward and downward.

Frankly, I have no idea of whether this means it's possible that a motorcycle moving sufficiently fast when it goes off the cliff could follow a trajectory that brings it next to a plan that goes into a dive under power... but I do say that it's not obviously impossible. I also say that it might well require an extremely high speed that in practice the motorcycle might not be able to reach in the time and space available, or maybe at all. --70.49.171.225 (talk) 05:08, 21 June 2014 (UTC)[reply]

In that case, the trajectories will diverge -- the plane will continue in its power-on dive until it impacts terrain several miles away, whereas 007 will fall to his death near the base of the cliff. :-( 24.5.122.13 (talk) 05:59, 21 June 2014 (UTC)[reply]

Not necessarily. If when the respective vehicles leave the clifftop the motorcycle's speed is higher than the plane's, or if the plane's nose-down attitude sets up a higher rate of descent, then the motorcycle's path is initially higher and it can cross the plane's path. --70.49.171.225 (talk) 03:23, 22 June 2014 (UTC)[reply]

Generally true, but not in this case -- in the shot taken when 007 goes over the edge on the bike, he's seen to be moving at the same speed as the plane. 24.5.122.13 (talk) 04:06, 22 June 2014 (UTC)[reply]

If James Bond knows he can't die, then he can take any risk he wants, with the full expectation of somehow surviving it intact. I'm reminded of at least a couple of other movie scenes. In Speed, the bus somehow jumps the gap between two sections of roadway despite those sections being on the same level. And in Indiana Jones and the Temple of Doom, a mine transport vehicle jumps a long (albeit downhill) gap in the rails, and not only lands safely, but squarely back onto the track and keeps going. ←Baseball Bugs ^{What's up, Doc?} carrots→ 09:28, 21 June 2014 (UTC)[reply]

In Speed, when the bus actually gets close to the gap you see that it hits some construction materials that were piled up near the edge. This would deflect it upwards as required for the jump. The scene is still impossible because until that last moment you had a clear view of the road all the way to the gap and there was no such pile of stuff on it. (And also because in practice a pile of material not intended as a ramp would not be strong and cohesive enough to effectively form one.) --70.49.171.225 (talk) 03:23, 22 June 2014 (UTC)[reply]

Well, in a sense it's true that James Bond can't die -- there have been at least five secret agents with the alias "James Bond 007", and when one is KIA'd, presumably he'd be replaced in short order ;-) 24.5.122.13 (talk) 19:08, 21 June 2014 (UTC)[reply]

This article lists some evidence against the James-Bond-is-a-code-name theory. (And in favor of the it's-just-a-show-I-should-really-just-relax theory.) -- BenRG (talk) 05:12, 22 June 2014 (UTC)[reply]

With regard to the Bondmobile, it might be that in Casino Royale, he won it back after it was stolen from the MI6 motorpool by the KGB in 1997... (This would also explain why he had to use a series of BMW cars as replacement vehicles in the meantime.) ;-) 24.5.122.13 (talk) 09:20, 22 June 2014 (UTC)[reply]

Which is more acidic? SO2 or SO3

There is acidity constant for SO₂ in its article. But I could not find or estimate the acidity of SO₃. Please help me. And I have another problem. Which has high bond strength? H₂ or HCl?--G.Kiruthikan (talk) 08:12, 21 June 2014 (UTC)[reply]

Bond strength is inversely proportional to bond length (a corollary of Coulomb's law) so just find which of the two has a shorter bond length, and that one has a stronger bond. Or you could just find the bond dissociation energy of each! which is the standard measure of bond length. --Jayron32 14:10, 21 June 2014 (UTC)[reply]

As for acidity, SO₃ is the anhydride of H₂SO₄, whereas SO₂ is that of H₂SO₃ -- guess which is the stronger acid? 24.5.122.13 (talk) 19:12, 21 June 2014 (UTC)[reply]

Not everybody knows that H₂SO₄, sulfuric acid, is stronger than H₂SO₃, sulfurous acid. That is, sulfuric acid is stronger than sulfurous acid in the short run. As a pollutant in air, sulfurous acid, formed from hydration of sulfur dioxide, will eventually oxidize to sulfuric acid. Robert McClenon (talk) 21:12, 21 June 2014 (UTC)[reply]

As a matter of fact, the reason why there's no acidity constant for sulfur trioxide is because its acidity is so mind-bogglingly high that it converts to acid completely in aqueous solution: SO₃ + H₂O → H₂SO₄ → H⁺ + HSO₄^- (note no equilibrium arrows -- the reaction goes completely to the right). 24.5.122.13 (talk) 21:38, 21 June 2014 (UTC)[reply]

H₂SO₄ does have a pKa (–3 in water), meaning that second reaction is either just a very strongly directed equilibrium or the actual acid-forming reaction is more complicated than that equation suggests. Well, "and" not or most likely. DMacks (talk) 03:56, 22 June 2014 (UTC)[reply]

And the first reaction also has an equilibrium constant, but again a very forward-shifted one (doi:10.1021/ja00536a008). DMacks (talk) 04:00, 22 June 2014 (UTC)[reply]

Hang on. All these answers appear to assume aqueous solutions, in which case we are not dealing with SO₂ and SO₃. The acidity/basicity of a compound is a measure of its propensity to donate/capture a proton. Since these two compounds have no protons to donate, these compunds can surely not be acidic? Perhaps the OP can clarify the intended question in this light. —Quondum 05:35, 22 June 2014 (UTC)[reply]

SO₂ and SO₃ are Lewis acids: they accept a pair of electron from H₂O. Ruslik_Zero 07:07, 22 June 2014 (UTC)[reply]

They are also Arrhenius acids: meaning that dissolving them in water produces excess hydronium ion; they do this as hydroxide acceptors. One way to represent the reaction of SO₂ with water is SO₂ + H₂O -> HSO₃^- + H⁺; the Arrhenius definition of an acid is any substance that, when dissolved in water, produces H⁺ ions. What they are not is Bronsted-Lowry acids; however that's why we have three common acid base theories (Arrhenius, B-L, and Lewis). Each of the three theories compliments the others, and none by itself completely captures all acid-base behavior. You can get to the B-L behavior in 2 steps, however, by considering the reaction of of SO₂ with water a separate reaction producing H₂SO₃, and then considering the B-L reaction the second step. It's all a matter of perspective. --Jayron32 20:18, 22 June 2014 (UTC)[reply]

Other Mammals which reach Sexual Maturity after age 10?

Other than Human Beings which other mammals on average take more than 10 years to reach Sexual Maturity? (Yes, I know there are valid cases of sexual maturity in Humans occurring prior to age 10, but on average, I'm pretty sure it is after)Naraht (talk) 10:35, 21 June 2014 (UTC)[reply]

Gorilla, for one. ←Baseball Bugs ^{What's up, Doc?} carrots→ 12:20, 21 June 2014 (UTC)[reply]

It is often highly correlated in mammals to size so look to whales, elephants and so on. A Google search of <"do not reach sexual maturity until * years" mammals> indicates (after only looking at the first few result pages): Orcas at around 15; Dugongs at around 10; female elephants at around 10; male short-finned pilot whales at 12 or later.--Fuhghettaboutit (talk) 15:39, 21 June 2014 (UTC)[reply]

As Fuhgettaboutit says, sexual maturity, as well as longevity, are often correlated to size. Human late sexual maturity and longevity are a special case, having to do not with size (humans being smaller than gorillas but longer-lived) but with language and learning. Having elders as a community memory is extremely useful for humans, especially pre-literate humans (but also literate humans). Also, human females are the only apes that have menopause, which is probably (but I haven't looked for a source) related to longevity, so that older women don't die in childbirth. Robert McClenon (talk) 17:27, 21 June 2014 (UTC)[reply]

The more I research this, the more it comes back to r/K selection theory. Animals with high K-selection strategy seem to both live longer and mature later in that lifetime. So age of ssexual maturity seems like a single facet of this... Thanx!Naraht (talk) 17:54, 22 June 2014 (UTC)[reply]

@Naraht: See also parental investment, which is usually closely linked to age to maturity. Humans and some other slow-to-mature species also have some neotenous traits. SemanticMantis (talk) 18:02, 22 June 2014 (UTC)[reply]

Why do people wrap food in the oven with aluminum foil?

Aluminum foil is highly reflective, so wouldn't wrapping food in aluminum foil make it take longer to heat up? If so, why do people wrap their food in aluminum foil before putting it in the oven? 65.92.5.124 (talk) 23:35, 21 June 2014 (UTC)[reply]

It's also highly conductive, so it doesn't make much of a difference in heating time. 24.5.122.13 (talk) 23:48, 21 June 2014 (UTC)[reply]

Yes. Remember that heat can be transferred in various ways. Food in an oven is heated by radiation from the gas flame or electric heating element, and a reflector will block this. But the flame or element heats the air near it by conduction, which heats the air in other parts of the oven by convection and/or conduction. This hot air in turn heats the food by conduction. --70.49.171.225 (talk) 03:31, 22 June 2014 (UTC)[reply]

You do it if you want to keep the moisture in. Dmcq (talk) 23:50, 21 June 2014 (UTC)[reply]

Is suppose you put the shiny side pointing in as well so the reflectivity is minimised? — Preceding unsigned comment added by Seans Potato Business (talk • contribs) 02:02, 22 June 2014‎ (UTC)[reply]

Discussed at Aluminium foil#Properties DMacks (talk) 03:47, 22 June 2014 (UTC)[reply]

It also helps retain moisture within the food, and minimizes subsequent cleaning of the pans, trays, and oven.--Shantavira|^{feed me} 11:01, 22 June 2014 (UTC)[reply]

Note also that reducing the radiative heat transfer is not necessarily an unwanted thing. It may very mildly increase the time it takes to heat up a large object but as stated above probably not by much. Conversely it can be an advantage when baking a pie or cheese cake or cake of some sort in the oven to reduce excessive browning or burning of the top. Usually this will involve covering just the top rather than wrapping and also generally only half way in (clarification: to the cooking time) if necessary. Nil Einne (talk) 14:10, 22 June 2014 (UTC)[reply]

There are two main reasons. First, as stated above, to keep moisture in. Second, there are many situations where slowing heat transfer is actually a good thing. If you are cooking something large and thick, it can easily burn on the outside before it even begins to heat up at the center. Aluminum foil greatly equalizes the distribution of heat inside. Looie496 (talk) 15:34, 22 June 2014 (UTC)[reply]

Thanks for all the answers. 65.92.5.124 (talk) 20:38, 22 June 2014 (UTC)[reply]

June 22

Square light year

Anything whose area is a square light year that you know about?? This is a huge unit of area. If my calculation is correct, it is 3.5 * 10^24 square miles (feel free to give a more accurate value if you can.)

Nothing in our solar system is this big; it's more than 10^12 times as big as the sun. Is this correct?? Georgia guy (talk) 01:21, 22 June 2014 (UTC)[reply]

it would be a massive understatement to say that nothing in our solar system would have an area of one square light year. A light year is about 10^16 kilometers, so a square light year would be 10^32 square kilometers. For comparison, the radius of the solar system is about 100 AU or about 1.5 10^10 kilometers. Thus, you'd need to lay out 1.3 million so solar systems end to end to make up a light year, and could fit about 1.7 trillion solar systems in an area of one square light year. --Jayron32 02:07, 22 June 2014 (UTC)[reply]

1 light-year is 9.4607×10¹⁵ m = 9.4607×10¹² km ≃ 10¹³ km, so 1 ly² ≃ 10²⁶ km². —Quondum 03:05, 22 June 2014 (UTC)[reply]

Ah yes, 10^16 meters. I messed that up. Thanks for correcting me. So, take three decimal places off of all of my length calculations and 6 decimal places off of my area calculations. In the end, however, it's still a metric fuckton of area, many orders of magnitude larger than the solar system.--Jayron32 20:12, 22 June 2014 (UTC)[reply]

What do you consider to be a "thing" for the purpose of defining the word "anything"? A cross section of the Oort cloud has an area of a few square light-years. Red Act (talk) 02:59, 22 June 2014 (UTC)[reply]

A square light year is around 10³² m². Orders of magnitude (area) ends with the below. PrimeHunter (talk) 20:29, 22 June 2014 (UTC)[reply]

**List of orders of magnitude for areas 10²⁷ square metres and larger.**
Factor (m²)	Value	Item
...
10³²	2×10³² m²	Roughly the surface area of an Oort Cloud
10³²	3×10³² m²	Roughly the surface area of a Bok globule
...
10³⁴	3×10³⁴ m²	Roughly the surface area of The Bubble
...
10⁴¹	7×10⁴¹ m²	Roughly the area of Milky Way's galactic disk

Sexual behavior in animals

Do any other animals (not human beings) engage in: (a) sex with other animals for pleasure, as opposed to procreation; (b) masturbation; (c) sex with different species; and (d) non-intercourse sex such as oral sex or anal sex? Also, if we are talking about scenario "a": how would the scientific researchers know if the animal was doing it for pleasure and not for procreation? Thank you. — Preceding unsigned comment added by 75.44.113.200 (talk) 03:42, 22 June 2014 (UTC)[reply]

(a) Dolphins and some monkeys such as bonobos; (b) IDK; (c) Deer occasionally try to copulate with cows; (d) Cats, ducks, monkeys and some other species have been known to engage in gay sex. 24.5.122.13 (talk) 03:59, 22 June 2014 (UTC)[reply]

Yes to all of the above. See Animal sexual behaviour. Red Act (talk) 04:05, 22 June 2014 (UTC)[reply]

Bears having oral sex ScienceApe (talk) 06:59, 22 June 2014 (UTC)[reply]

I question your position that anal and oral sex are "non-intercourse" sex. -- Jack of Oz ^{[pleasantries]} 09:42, 22 June 2014 (UTC)[reply]

(a) dogs (b) dogs (c) dogs (d) dogs.--Shantavira|^{feed me} 11:13, 22 June 2014 (UTC)[reply]

Denatured Isopropyl alcohol

I have a bottle of rubbing alcohol, 70% isopropyl. It says it's denatured, but what's the point of that? I'm under the impression that denaturing is done to make it unfit to drink for tax purposes, but isn't isopropyl unfit to drink in the first place? ScienceApe (talk) 06:57, 22 June 2014 (UTC)[reply]

I own a business that uses denatured ethanol as a solvent and degreaser, and you are correct that "denaturing" in that context refers to adding poisons and unpleasant tastes to high proof ethanol otherwise acceptable as a beverage, instead intended for industrial use, to render it unfit for beverage use. Avoidance of alcoholic beverage taxes drive that denaturing process. But there is a long history of foolish attempts to use other alcohols as beverages, even though they are unfit for human consumption. There have been many incidents of mass poisonings in India, for example, when people tried to use other types of alcohols in beverages. So, adding extremely bad tasting trace additives to isopropyl alcohol is a safety measure intended to prevent dangerous abuse of a substance that can get you drunk, and then you go blind and die. Cullen³²⁸ Let's discuss it 07:25, 22 June 2014 (UTC)[reply]

Bug id

Hi. Today I found an interesting looking bug attached to a pair of my wife's sandals in the garden. Here's the little fella: [12] S/he measures around 4-5cm long (the bug, that is, not my wife), and I'm in the UK. What is it? Thanks :) — sparklism ^hey! 17:04, 22 June 2014 (UTC)[reply]

That's a nice specimen of a beetle. Specifically a scarab beetle. It might be a European chafer, based on the antennae shape. On the other hand, yours would be on the very high end of size for them, and the pronotum might not be quite right. Getting a beetle ID to species level is quite hard unless it's a very common species with few look-alikes. If you want to learn enough about insect morphology, you can use a Key_(biology) to be sure. Here's a nice intro to beetle ID [13]. SemanticMantis (talk) 17:59, 22 June 2014 (UTC)[reply]

That's great - thanks! :) — sparklism ^hey! 19:05, 22 June 2014 (UTC)[reply]

Transmission line connection via tapered sections

It is well known that to match two transmission lines of differing impedance using a tapered section introduces a low frequency cutoff that depends upon the type and length of taper. However, I am not clear as to whether connecting 2 TLs of the same impedance but differing dimensions together with a tapered section will introduce such a frequency limitation. Am I correct in thinking that no low frequency cutoff will be apparent in the latter case? --86.180.143.223 (talk) 20:40, 22 June 2014 (UTC)[reply]

@@ Line 615: / Line 615: @@
 :That's a nice specimen of a [[beetle]]. Specifically a [[scarab beetle]]. It might be a [[European chafer]], based on the antennae shape. On the other hand, yours would be on the very high end of size for them, and the [[pronotum]] might not be quite right. Getting a beetle ID to species level is quite hard unless it's a very common species with few look-alikes. If you want to learn enough about [[insect morphology]], you can use a [[Key_(biology)]] to be sure. Here's a nice intro to beetle ID [http://entnemdept.ufl.edu/choate/beetles.pdf]. [[User:SemanticMantis|SemanticMantis]] ([[User talk:SemanticMantis|talk]]) 17:59, 22 June 2014 (UTC)
 ::That's great - thanks! :)[[User:Sparklism| — sparklism]] <sup><small>''[[User_talk:Sparklism| hey!]]''</small></sup> 19:05, 22 June 2014 (UTC)
+== Transmission line connection via  tapered sections ==
+It is well known that to match two transmission lines of ''differing'' impedance using a tapered section introduces a low frequency cutoff that depends upon the type and length of taper. However, I am not clear as to whether connecting 2 TLs of the ''same'' impedance but differing dimensions together with a tapered section will introduce such a frequency limitation. Am I correct in thinking that no low frequency cutoff will be apparent in the latter case? --[[Special:Contributions/86.180.143.223|86.180.143.223]] ([[User talk:86.180.143.223|talk]]) 20:40, 22 June 2014 (UTC)