Wikipedia:Reference desk/Archives/Science/2009 October 31

= October 31 =

Foreign accent syndrome and stroke recovery
I was curious about a case I read about a few years back, regarding a patient who had what, after searching here, I discovered to be foreign accent syndrome. It got me to thinking - if, after a stroke or other brain injury, in rare cases people can speak only in an accent, have rehabilitation workers ever experimented to see if a person who has lost their speech might recover it if taught to speak differently?

I'm aware there might be some flawed biology I'm not catching, but: If a person's neural patterns are such that they can't do the numerous things necessary to form speech, could there still be some mechanism that would let them produce it differently? could those with FAS speak that way because, in essence, they have "relearned to speak," in the same way a child learns to speak in his or her own unique voice? (Since every voice, even without an accent, sounds a bit different.)209.244.187.155 (talk) 00:32, 31 October 2009 (UTC)


 * Reading your question, I think you've missed that the people aren't really speaking in a foreign accent. It isn't that they've learnt to speak in a different accent, it's that brain damage affects how they pronounce some sounds in a consistent manner. People who hear them interpret this as them speaking in a foreign accent. For example, someone who previously had a rhotic accent might suffer brain damage that affected their ability to pronounce the 'r' in words like 'Arthur'. Their friends and family, who also speak with rhotic accents, perceive this as them speaking a non-rhotic accent (like many British accents). 86.139.237.128 (talk) 02:32, 31 October 2009 (UTC)


 * Okay, you're right, that's what I was getting confused by; thanks.4.68.248.130 (talk) 09:15, 31 October 2009 (UTC)


 * Stroke symptoms can be very strange, and it's hard to predict what might or might not be possible. There are, for example, cases of people who have lost the ability to talk but are still able to sing. Looie496 (talk) 04:27, 31 October 2009 (UTC)


 * I heard from the Media about one Czech turist who had traumatic brain injury after falling from his bike in London. Then, when he woke up in the British hospital he start speaking in fluent English with British accent, something he certainly couldn't done before. So, it seems like the brain could be very flexiable sometimes (but not always). For instance, it seem like the visual cortex of people who lost their sight is being used extensively for the sense of touch -this ability of the brain to gain new functions or to rewire itself isa part of its neural plasticity. But what you asked is more complicated, as we are talking about something more complicated than sensing-language is learning dependent high function and it can't appear out of the blue. So it seem much more similar n to one regression to his/hersecond language, that happened many times during  degenerative diseases such as Parkino's disease. That is, one major function is lost, so the brain must use the more preserved areas and the previously dominant brain areas can't longer overpower/inhibit the areas that contain these secondary abilities.--Gilisa (talk) 17:39, 31 October 2009 (UTC)


 * I am glad he survived. It is sad to see a Czech bounce. Cuddlyable3 (talk) 12:43, 1 November 2009 (UTC)

Increasing the size of the human penis?
Is there any medications available that actually work to permanently increase the size of the penis? —Preceding unsigned comment added by 84.68.36.19 (talk • contribs)
 * No. -- Jayron  32  01:23, 31 October 2009 (UTC)


 * We have an article on that: Penis enlargement. Red Act (talk) 01:35, 31 October 2009 (UTC)


 * No.  —Preceding unsigned comment added by 79.75.106.210 (talk) 01:50, 31 October 2009 (UTC)


 * You wouldn't enjoy permanent enlargement this way though there is a popular temporary way. Cuddlyable3 (talk) 14:40, 31 October 2009 (UTC)


 * I always get e-mails that offer me to buy enlargement kit-all I have to do is to give my address and c. card number and a simple kit will be sent to my post office box. I never tried it, but maybe you want me to give you connection details?--Gilisa (talk) 18:12, 31 October 2009 (UTC)

With all due respect, I hope you're kidding Gilasa. Let me put it this way: if the information is in your spam box, the information fails being trustworthy as soon as your credit card information changes the outcome. Magog the Ogre (talk) 20:12, 1 November 2009 (UTC)

Nifty Propulsion Device
Someone pointed this thing out to me and I don't know enough physics to determine whether it makes sense. Can someone who knows more about it give a ruling? Black Carrot (talk) 04:45, 31 October 2009 (UTC)


 * This is the EmDrive. As a reactionless drive, it blatantly violates the conservation of momentum and cannot work as claimed.  After the magnetron is turned on, the microwaves aren't going to do anything except bounce around and get absorbed with absolutely no effect on the cavity's total momentum.  The energy will then be radiated as blackbody photons, though asymmetries in the device's geometry may provide a miniscule force on the "drive".  In other words, the "drive" will function much better if the end facing the magnetron is removed, because the photons will then serve as a tiny reaction mass.  --Bowlhover (talk) 06:36, 31 October 2009 (UTC)
 * Someone who knows more about it has given a (rather damning) ruling, and you can see it here: . The basic error Shawyer makes is to assume the impulse imparted on a wall during a particle-wall collision is in an incorrect direction. You can see this yourself by looking at figure 2.4 of (an earlier version of the same document). In the "updated" version, Shawyer removes the section which makes his error obvious. Someone42 (talk) 07:00, 31 October 2009 (UTC)
 * Roger Shawyer claims to have calculated and measured on a demonstrator engine 16mN thrust from an input power of 850W. Dr. Costella accuses Roger Shawyer of being a charlatan who defrauded a government agency (the UK Department of Trade and Industry). I smell a libel suit where lawyers are bound to earn. Cuddlyable3 (talk) 14:35, 31 October 2009 (UTC)

The only real test will be when someone actually takes his device up into orbit and it moves.When is this going to happen?80.0.98.26 (talk) 11:14, 1 November 2009 (UTC)Trevor Loughlin
 * Hopefully never, because that would cost a lot of money and I would hope that the people who control such quantities of money would do a bit of investigation before giving it away. Seriously, the guy is a complete idiot (or a con man). He doesn't even claim some hitherto undiscovered law of physics, he claims that his drive works in the framework of standard electrodynamics. But it's a theorem that momentum is conserved in electrodynamics (Noether's theorem), so he's wrong and that's the end of it. The most valuable thing about this fiasco is that it's a lesson in just how far New Scientist's journalistic standards have fallen. It's barely above the level of a supermarket tabloid at this point. The problem isn't so much that it's a terrible magazine—there are lots of those—but that people still trust it as a source of physics news. It's disturbing how often it gets used as a reference in Wikipedia articles. Greg Egan wrote a plea to save New Scientist in the wake of this story, but I think it's too late for that. I would instead plead with people to cancel their subscriptions. -- BenRG (talk) 13:23, 1 November 2009 (UTC)

Dry friction
What actually is dry friction? Can i call viscosity as fluid friction and vice-versa ? —Preceding unsigned comment added by 122.168.213.193 (talk) 11:17, 31 October 2009 (UTC)
 * Not really. Dry friction is the lateral friction between touching surfaces of solids, and may be classified as either static or dynamic depending on whether the surfaces are stationary or moving relative to one another.  Viscosity is the resistance of a fluid to flow, and whilst the name "fluid friction" sounds appropriate, it's ambiguous as the term is already taken to be the friction between two solid surfaces separated by a fluid, or sometimes the friction between layers of a fluid with relative motion to each other. See  this.--Leon (talk) 13:55, 31 October 2009 (UTC)

Area dependency of friction
It is stated that frictional force is independent of area of contact then why we fell it harder to ride a bicycle with flat tire (air less) —Preceding unsigned comment added by 122.168.213.193 (talk) 11:26, 31 October 2009 (UTC)


 * First let me point out (before Steve Baker starts jumping up and down) that that description of the friction force as independent of the area is intended for non-sticking flat hard surfaces. Tires don't meet those criteria. More importantly, though, you are confusing rolling friction (on the bike's tires) with sliding friction (which is the kind of friction this description is intended for). Dauto (talk) 11:34, 31 October 2009 (UTC)
 * Sliding is not a factor. Squashing and unsquashing the rubber of a flat tyre consumes (i.e. converts to heat) energy, see Rolling resistance, that must be provided by the rider. Cuddlyable3 (talk) 14:11, 31 October 2009 (UTC)

A noise meter to measure outdoor road noise pollution in the UK?
Noise or sound meters are less expensive than I thought, and buying is cheaper than hiring. I want to measure outdoor road noise pollution, in a way that complies with UK standards for doing so - whatever they are. I think this requires using an "A" digital frequency filter, which seems available on many meters. But rather than looking at a fluctuating meter and mentally trying to average the reading, are there any meters that will do this automatically - that will tell you what the average reading was over a minute say? Since I will avoid rainy situations a waterproof meter is not necessary. Thanks 78.144.206.114 (talk) 11:37, 31 October 2009 (UTC)
 * It sounds (pun) that you want to measure A-weighted long-term average sound level as defined in BS 7445 / ISO 1996. Look for a noise meter that has an analog or digital logging output that you can connect to a PC. If it is analog then you need an A-to-D converter. THe PC can store the data, calculate average(s) and show them on a spreadsheet. A common mistake made by professionals who should know better is to take an average of dB(A) measurements. This is wrong because dB (decibel) is a logarithm of a power measurement. The correct way is to convert from the dB(A) values to power(A) values, take their average, then convert back to dB(A). For the legal background in the UK see the Noise and Statutory Nuisance Act 1993 and the EU Environmental Noise Directive. Cuddlyable3 (talk) 14:05, 31 October 2009 (UTC)

Thanks, although where I want to take the noise readings will be a very long way from my desktop computer. Are there any that can do the "averaging" themselves? Thanks. 78.151.126.29 (talk) 21:35, 31 October 2009 (UTC)


 * Consider using a portable Laptop or Netbook. Battery time is a limitation. Cuddlyable3 (talk) 22:05, 31 October 2009 (UTC)

Cicely of Oxford Royal Physician
I read somewhere that Cicely of Oxford was Court Physician to either Richard II or England or Edward III of English. Is there any way to confirm this? —Preceding unsigned comment added by 76.200.166.39 (talk) 11:51, 31 October 2009 (UTC)
 * Both and  claim that she was Court Physician to Edward III, although neither look particularly reliable.  The whole claim looks rather doubtful, as I cannot find any other references to Cecily or Cicely of Oxford, and historical works which would have been expected to mention a fact so interesting as a fourteenth-century female physician (e.g. this survey of royal physicians in the reign of Edward II and immediately after) don't have anything to say about it. Warofdreams talk 23:06, 31 October 2009 (UTC)
 * P. C. Doherty is a pretty bad writer of detective stories, but he has strong academic credentials as a 14th century history, so if he claims Cicely of Oxford was physician to Edward III, he probably has a good basis for saying so. Looie496 (talk) 02:49, 1 November 2009 (UTC)

Epidermal growth factor
Hi I'm a little confused about how epidermal growth factor (EGF) is produced in the human body. Are there cells that produce it? The article on EGF says 'sources' are macrophages, platelets, urine, plasma and milk. What does this mean? Do macrophages and platelets produce EGF? I can't imagine urine/milk producing anything, or does it mean ingesting urine/milk would provide a person with a source of EGF? Any clarification would be great, thanks RichYPE (talk) 14:20, 31 October 2009 (UTC)


 * I think you have to go to the cited source of the information which is Cotran, Ramzi S.; Kumar, Vinay; Fausto, Nelson; Nelso Fausto; Robbins, Stanley L.; Abbas, Abul K. (2005). Robbins and Cotran pathologic basis of disease. St. Louis, Mo: Elsevier Saunders. ISBN 0-7216-0187-1.Cuddlyable3 (talk) 21:33, 31 October 2009 (UTC)


 * Epidermal growth factor is a protein, and as such is produced by protein synthesis, which occurs in cells. The megakaryocytes that give rise to platelets, synthesize EGF (see this paper, as do macrophages. When EGF is found outside of cells, it is because it has been secreted from the cells that produced it. --NorwegianBluetalk 11:12, 1 November 2009 (UTC)

Hydrocephalus
good evening, I just want to ask about hydrocephalus.. i am a Physiotherapist, and i have a patient who have one, my main concern is that she keeps on crying while the therapy is on going, and im afraid if this is bad or dangerous to her, sometimes she turns cyanotic.. hope you can help me and also I want to know what technique can i improve her trunk control for she will be able to sit and walk independently... waiting for your response": Erlinda M. Mendoza —Preceding unsigned comment added by 120.28.71.159 (talk) 15:46, 31 October 2009 (UTC)   —Preceding unsigned comment added by 86.4.186.107 (talk)


 * Erlinda, I'm sorry but we don't give medical (or physiotherapy) advice on the Reference Desk. Receiving medical advice from strangers for the treatment of a third person is very risky, I'm sure you can understand this. If you are a chartered or qualified physiotherapist you must surely have professional colleague or seniors who can give you advice. Of course we have an article on hydrocephalus, reading this might be helpful. Caesar&#39;s Daddy (talk) 16:04, 31 October 2009 (UTC)

Sounds of a Teaspoon in a Mug of Milk?
Take a mug of milk (or milky tea, or milky coffee). Heat it. Take a teaspoon, and tap it on the base of the mug (but from inside the mug, like you're stirring it.) Listen to the sounds, specifically the pitch of the sound. WHAT CAUSES THIS? ASCII image related.

Teaspoon in a mug with hot milk,

move it up and down, tapping mug base,

what the hell are the sounds like that for?

No answers from anyone what has not tried this please. Remember Civility (talk) 19:01, 31 October 2009 (UTC)


 * Before putting in the milk the mug gave out a tinkle, effectively acting as a bell. As the milk went in the resonant frequency went up because of the smaller part of the mug that can resonate freely, but changed progressively from a tinkle to a dampened knock sound. Then I drank the milk yum-yum. Cuddlyable3 (talk) 21:28, 31 October 2009 (UTC)
 * That's "Original Research", I'm not sure that's allowed ;-)) Richard Avery (talk) 22:45, 31 October 2009 (UTC)


 * YOU DIDN'T TRY IT DID YOU? :p Take a full mug of milk.  Tap.  Listen to that sound.  Tap again (not adding or removing any fluid).  Listen to that sound.  tap - tap - tap - tap - tap - tap - tap - tap, listen to the sounds of the taps.  No liquid added or removed.  Remember Civility (talk) 22:49, 31 October 2009 (UTC)
 * I tried it with a heated mug of water (my girlfriend drinks milk, but there's none in the fridge at the moment), and it sounded quite unremarkable. There are a lot of variables here that will affect what is heard with this experiment -- the thickness, shape and material of the mug, how full the mug is, the acoustic properties of the surface the mug is placed on, possibly the thermal properties of the liquid, mug, and surface, since the liquid is heated, etc.  Could you please record the sound and upload it, so we can hear whatever it is you're hearing?  Decent laptops nowadays have built-in microphones (even if you can't necessarily see where it is), it's easy to record using the Sound Recorder that comes with Windows, and I think it's fairly straight-forward to upload a file using the "Upload file" link under the "toolbox" section of this page.  Red Act (talk) 01:34, 1 November 2009 (UTC)
 * As someone who has heard this noise, I can tell you that what causes this is the same thing that causes any sound. When the spoon hits the mug, the spoon and mug vibrate.  The milk in the mug affects the vibrations of the mug and the spoon, and what you hear is a combination of all the vibrations. See sound &mdash;Akrabbimtalk 01:04, 1 November 2009 (UTC)


 * Most of the respondents don't seem to have noticed the phenomenon that I think Remember Civility is referring to: correct me if I'm wrong, RC, but I believe it is that when the mug is tapped, the pitch of successive taps progressively rises for a time. I've noticed and wondered about this when stirring hot tea or coffee: at first I assumed it was due to the rising temperature of the mug (due to heat transfer from the beverage) altering its acoustical properties, but it also seem to happen if one waits long enough before stirring for the beverage and mug temperatures to have stabilised. An alternative conjecture is that tapping (or stirring) releases dissolved gasses in the beverage, altering its density and therefore acoustical properties. I too would really like to know the correct answer to this. 87.81.230.195 (talk) 06:35, 1 November 2009 (UTC)


 * I haven't tried this (not a tea drinker), but I've certainly noticed something which might be similar. If you fill a glass with hot water from the faucet, and drop some silverware in, it rattles with a sound which I would describe as a knock or a tap.  But a few minutes later, if you jiggle the silverware around, the sound is much more tinkly.  (And I notice this phenomenon all the time, when I'm soaking the glass and the silverware prior to washing them.)


 * There's something else I notice. When I first run the hot water into the glass from the faucet, it's cloudy.  A few minutes later, when the sound has changed, the appearance has changed, too -- now the water is clear.


 * You can probably see where I'm going with this, and it's the same suggestion 87.81.230.195 made already. Hot water fresh out of the tap contains a lot of dissolved gases.  The dissolved gas seems to quite significantly muffle or deaden sound.  It takes a few minutes for the gas to come out of solution, and when it does, both the appearance and the sounds are much clearer. —Steve Summit (talk) 14:35, 1 November 2009 (UTC)
 * I'm fairly certain the cloudiness is due to temporary hardness (not dissimilar to the limescale in the kettle). Whether this has an effect on the noise, I'm not sure, but it's possible. - Jarry1250 [Humorous? Discuss.] 15:35, 1 November 2009 (UTC)


 * editors who've noticed the rising pitch are correct. I didn't want to mention it for fear of "planting" the thought.  I've done a bit more search and it is mentioned in an old [i]New Scientist[/i], see this link, and then, 14 years later, they have another, fuller, bit of text.  Note that stirring can "reset" the sound back to a lower pitch. Remember Civility (talk) 15:33, 1 November 2009 (UTC)


 * I just did some original research regarding this question, in a very literal sense of the phrase: I have now tried this three times with pure boiling hot water, and three times with boiling hot water with cocoa powder in it.  All three times pure water was used, there was no discernable rise in pitch.  All three times cocoa powder was used, there was a rise in pitch.


 * The third time each way was done simultaneously, and performed identically except for the cocoa powder: I brought identical amounts of water in identical mugs to a boil at the same time in a microwave oven.  I moved the two mugs simultaneously from the microwave to adjacent tiles on the same countertop.  I poured some cocoa powder into one of them.  I stirred both mugs simultaneously with identical teaspoons briefly, and then simultaneously held the two spoons in a bottom corner of their respective mugs briefly, to essentially eliminate the swirling motion of the liquid in each. I then repeatedly tapped the bottom centers of the mugs with the spoons in alternating order.  The pitch in the pure water, to the best of my hearing ability, stayed constant.  The pitch in the cocoa started off considerably lower than in the pure water, and ended up if anything slightly higher.  In neither case did bubbles come to the top of the liquid during the tapping process.


 * It certainly appears to be quite important that there be a solute in the water. However, it isn't necessary for the solute to be milk, as the OP suggests, since the cocoa powder I used does not contain any milk.  The cocoa powder I used was Ghirardelli Sweet Ground Chocolate and Cocoa, which contains sugar, cocoa (processed with alkali), unsweetened chocolate, soy lecithin and vanilla.


 * The "tiny bubbles" hypothesis put forward by Cecil Adams seems dubious to me, as I could not see any bubbles reaching the surface of the liquids during the tapping process. And the "changing vortex" hypothesis doesn't make sense, either, because the liquid was essentially stationary in both mugs during my final experiment.  Red Act (talk) 17:57, 1 November 2009 (UTC)


 * If stirring the liquid really does "reset" it - then it has to be something to do with the vortices (or lack thereof). Bubbles might be knocked out of solution by stirring - but it's hard to imagine that more could be added - hence stirring couldn't reset things if bubbles were the cause.  Stirring won't reset the temperature - so the effect of gradual cooling can't be the cause either.  The idea that the liquid has to be moving in some specific manner probably accounts for some of what's going on.  Sound waves will get dragged around with the fluid - so you could imagine different resonant pathways in rotating fluid versus stationary.  Using a curved spoon to do the tapping will certainly start up some motion of the liquid - and that might easily be "reset" by stirring.  Changing the ingredients of the liquid would change viscosity and perhaps the speed of sound - so it should be no surprise that this is a determining factor. SteveBaker (talk) 22:00, 1 November 2009 (UTC)


 * How about this for a hypothesis: Suppose the liquid is spinning (eg after stirring) in a smooth, circular path with more or less laminar flow.  In stationary liquid, the sound from a tap made in the center would travel radially outwards until it hit the side of the cup - but in a spinning liquid, it has to travel around in a spiral.  This changes the distance it has to travel thereby altering the resonant frequency - and also alters the angle at which the sound waves hit the side of the cup changing refractive patterns of the sound through to the air outside.  Either of those things could change the pitch that you hear.  However, because you're using a complicated curved spoon to do the tapping, each movement of the spoon causes turbulant eddies to spin off from it.  Progressive taps cause more and more turbulance - and after enough taps, the spinning of the liquid is broken up into much more random motion at small scales and very little laminar flow - resulting in approximately equal travel times for the sound.   Stirring the liquid restores the large-scale laminar flow and allows the experiment to be repeated.


 * Suggested experiments:
 * Try tapping with a thin, cylindrical object (a glass rod would be perfect) - trying to keep the rod in the center of the cup. This ought not to disturb the flow of the liquid so much - so (if my hypothesis is correct) it should take many more taps to mess up the flow rate and get the pitch of the sound to rise.
 * Try messing up the flow of the liquid with random motions of the spoon instead of smoothly stirring it. If the hypothesis is correct, this should immediately "reset" you to the highest sound frequency instead of the lowest.
 * SteveBaker (talk) 22:11, 1 November 2009 (UTC)