Wikipedia:Reference desk/Archives/Science/2007 June 17

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[edit] June 17

[edit] Lead into Gold

From looking at the periodic table, it appears that synthesizing lead from gold should be fairly easy. But what about the more traditional goal of turning lead into gold? Is that possible, and if so, what nuclear reactions would be involved? --Carnildo 00:46, 17 June 2007 (UTC)

It's called transmutation, but sadly nuclear transmutation#Gold only lists the Pb -> Au direction. --TotoBaggins 01:28, 17 June 2007 (UTC)
Pb gamma decay can turn Pb into Au, but it's just not economical. --antilivedT | C | G 04:17, 17 June 2007 (UTC)
I can't find a link but I remember an article talking about turning lead into gold. Unfortuantly, they only made a thousand atoms and they were radioactive. Ozone 08:39, 17 June 2007 (UTC)

That is so old. Were trying to turn neptunium into plutonium now, it's worth a lot more.

The transmutation of gold into lead by neutron capture and beta decay looks straightforward. Hit gold with neutron, get lead. But how would the "gamma decay" be caused? This same question was asked and no answer was provided a month or so ago. It would be a good addition to the transmutation article. Edison 20:54, 17 June 2007 (UTC)

I'm not quite sure myself... I've read it in a book a long time ago, which also said gamma decay will transmutate an element into another element before them in the periodic table. I doubt it's a reliable source, and this doesn't say anything on the process of it. --antilivedT | C | G 06:47, 18 June 2007 (UTC)

The article Nuclear transmutation used to contain a section entitled "Photoneutron process" which outlined how gold could be made from mercury (OK, not lead). That section was removed, possibly unintentionally, by The way, the truth, and the light on 28 April 2007, in an edit (mis-?) labeled "minor". --mglg(talk) 21:01, 18 June 2007 (UTC)

[edit] Kaganaias - Expert help needed...

I've created the Kaganaias article from a PDF which is mentioned in the article. However, I have a few questions - 1) On the PDF it says Kaganaias has been assigned to Platynota because Sarah Evans did not know which part of Mosasauridae it went into. Is this correct, as I've never been heard of a single genus being assigned to a large group like that, usually families. 2) This brings up another question - This site ([1]) says that Platynota is an infraorder, where as other pages on Wikipedia say it is a superfamily. Which is correct? 3) And what the heck is Varanoidea? It was in a taxobox right next to Platynota (actually in the text of this article), so I assumed they both meant the same thing? If you'd be able to figure out what's going on, it would be a great help. It would have been better if the PDF had a better systematic paleobiology level thingy... :) Thanks, Spawn Man 01:52, 17 June 2007 (UTC)


Woah, you make no sense

[edit] Atom's ionoc charge and bonding

Hello, I am studying for my highschool science finals. The questions are:

Using the periodic table, how do you determine a certain atom's ionic charge?

Using the period table, how can you determine what a certain atom will bond with?

Thank you!

Does our periodic table help ? StuRat 13:45, 18 June 2007 (UTC)

[edit] What is the oldest matter in existance?

oxygen. Please explain Willy turner 04:04, 17 June 2007 (UTC)

Oxygen is a relatively new addition to Earth's atmosphere. As for the whole universe, the oldest matter would have to be whatever existed right after the big bang. - Pharaonic 07:07, 17 June 2007 (UTC)
Caveat - The oxygen in question was present on earth, but not in gaseous form, prior to the biological processes which released it into the atmosphere. It probably took the form of carbon dioxide or silicon dioxide.Nimur 09:31, 17 June 2007 (UTC)
If what you want to know is which elements that were first formed, the answer is hydrogen, helium and litium. These were formed during a three minute period, a few minutes after the Big bang, see Big Bang nucleosynthesis. Heavier elements were formed later, see Stellar nucleosynthesis. --NorwegianBlue talk 08:10, 17 June 2007 (UTC)
Some definition of "old" must be established before this question has meaning. In some sense, all matter is the same age (if you will accept a loose definition of the starting-age). If you only consider the nuclei of atoms, then the solar fusion process which created it would dictate its age. If you are considering the chemical substance of which it is now a part, the time scale might be dramatically shorter. Finally, if you consider the physical form or structure of the matter, it might be extremely young. Nimur 09:41, 17 June 2007 (UTC)
Neutrinos effectively decoupled from other matter approximately 1 second after the Big Bang, well before nucleosynthesis started - see Timeline of the Big Bang. So the neutrinos in the cosmic neutrino background have a good claim to be the "oldest" matter - however, they are very hard (maybe impossible ?) to detect. Gandalf61 14:40, 17 June 2007 (UTC)

[edit] Is there a maximum temperature?

There is an abolute minimum temperature. Is there a maximum? And if not, what is the highest temperature that has ever existed, and what/where is the hottest thing in the universe currently? Willy turner 04:04, 17 June 2007 (UTC)

See absolute zero. Dismas|(talk) 04:25, 17 June 2007 (UTC)
There is a very thorough answer to this in the archives, at Wikipedia:Reference desk archive/Science/2006 October 15.--Shantavira|feed me 07:16, 17 June 2007 (UTC)
Try plank temperature for the, I think, maximum. Ozone 08:37, 17 June 2007 (UTC)
That would be planck temperature. The article has some details. Strictly speaking, it is the theoretical boundary above which quantum mechanical descriptions break down. In real life, many other issues would cause a particular treatment or simulation to break down at far lower temperatures, so this "upper bound" can be brought even tighter. Nimur 09:34, 17 June 2007 (UTC)
He was talking "absolute," I assume this means theoretical and not practical. Ozone 04:37, 18 June 2007 (UTC)

[edit] Wax Solubility

Is candle wax soluble in ethanol? If not what other solvents dissolve it? Thank you. Ozone 08:34, 17 June 2007 (UTC)

Candle wax is a solid at room temperature. It is a non-polar substance, so presumably ethanol or other nonpolar solvents should be able to dissolve it. The solubility almost certainly depends on temperature. The paraffin article states:
It is mostly found as a white, odorless, tasteless, waxy solid, with a typical melting point between about 47 °C and 64 °C. It is insoluble in water, but soluble in ether, benzene, and certain esters. Paraffin is unaffected by most common chemical reagents, but burns readily.
Hope this helps, Nimur 09:39, 17 June 2007 (UTC)

Paraffin wax is slightly soluble in hot isopropyl alcohol, see here . Xylene and toluene may be better solvents for paraffin wax, but please check. Hope this helps, Dr_Dima.

Not all candles are made of paraffin. See candle. The redirect from candle wax to paraffin is somewhat misleading IMO.--Shantavira|feed me 10:30, 17 June 2007 (UTC)
True, good point. I'm gonna fix this. Dr_Dima.
Done. Dr_Dima.
I'm not entirely convinced this is correct. Not all candles are made of paraffin, but then not all candles are made of wax. An article claiming that tallow is "wax" seems problematic to me; do you have a reference for this? --Trovatore 20:59, 17 June 2007 (UTC)

Thank you for your help, I should have checked the parrafin article first. When producing the solution would the wax have to be molten, or could it dissolve from the solid? Ozone 19:40, 17 June 2007 (UTC)

My guess is that solid wax would dissolve much slower (perhaps on the timescale of days or weeks), while liquid paraffin would dissolve much more rapidly. See rate of solution for some background. It is also possible that the solid form might never dissolve unless melted (see precipitate). I don't know which is the case for paraffin, but you can probably find out in a chemistry reference book or with an internet search. Nimur 13:37, 18 June 2007 (UTC)

[edit] Speaking into a fan

Does anybody know why your voice changes when you talk to a fan? Is it maybe because you are decreseing the speed of sound, no I guess it would be better to say the displacement of sound?? Bastard Soap 10:20, 17 June 2007 (UTC)

for a football/soccer fan, it's mostly the pitch of the voice that changes ;) . For an electric fan, the modulation of the sound waves by rotating blades would be my prime suspect. Our auditory system sometimes does funny things with ampitude- or frequency-modulated sound, especially when there is some interaural difference; so if you record it in mono and then listen to the playback, the effect may change quite a bit. You can do the experiment and tell us what you hear. Seriously, it could be quite a nice project. Cheers, Dr_Dima.

I don't think I get your drift man. Could you refrase? Bastard Soap 16:49, 17 June 2007 (UTC)

I've never heard of this effect, but I'll try it out tomorrow at my office as I've got a fan there on my desk. But an obvious guess would be the Doppler effect: the blades reflect the sound back to you, but because they are moving, they change the pitch, and you may end up hearing a funny interference or beat (acoustics). Simon A. 20:17, 17 June 2007 (UTC)
There might be some contribution from the Doppler effect, but I think you're ignoring the obvious here: a just plain ordinary echo, except that it only echoes sometimes, because the fan blade is in the way sometimes and sometimes not. So you get this peculiar choppy echo of half of the waveform, in an on-off-on-off pattern. I can't believe you've never tried this; you really should, as the effect is quite striking. --Trovatore 20:24, 17 June 2007 (UTC)

Play known sounds like sine waves and then record it and look at the waveform. It's probably just a result of the sound being reflected back at you intermittently. See rotary woofer for an interesting tangent. — Omegatron 04:40, 18 June 2007 (UTC)

Hey Trovatore, I tried it out and did not get an echo at all. I'm disappointed. But my desk fan has plastic blades, maybe that damps the sound to much and it only works with metal ones? Simon A. 21:00, 18 June 2007 (UTC)
I think plastic blades will work. How big is the fan? If it's just one of those four-inch desk models, I'm not too surprised. --Trovatore 06:38, 19 June 2007 (UTC)
Somewhat related is the Leslie box, which is a rotating speaker. The article keeps on calling it a Doppler effect, but I'd say the variation in volume is more important that the pitch-variation. DirkvdM 07:37, 19 June 2007 (UTC)
What article? —Tamfang 04:49, 20 June 2007 (UTC)
The article I have now made that link redirect to. Sorry about that. DirkvdM 09:01, 20 June 2007 (UTC)

[edit] Re:Amputation

Hi all..I'll go straight to the point. When a patient has a limb amputated, where does the amputated limb go afterwards? Is it cremated or returned to the patient for some purpose? -Zachary crimsonwolf 13:26, 17 June 2007 (UTC)

I believe it is usually disposed of as medical waste and incinerated. --Joelmills 13:41, 17 June 2007 (UTC)

Ah. Okay. Thanks, and cheers!!! -Zachary crimsonwolf 13:57, 17 June 2007 (UTC)

I wonder if this disposal is an extra charge on the bill. (They really ought to include this service for free, considering that the patient has already paid an arm and a leg.) StuRat 13:34, 18 June 2007 (UTC)

Nice pun. I agree with StuRat. -Zacharycrimsonwolf 12:50, 20 June 2007 (UTC)

You know how hospital food is pretty bad..... Gzuckier 18:29, 20 June 2007 (UTC)

[edit] Help to identify an Australian bird

"What am I?"
"What am I?"

Does anyone know what this bird is? I've tried to identify it on the net with no luck. It was taken in Tomatoe Lake, Perth, Western Australia. 31°58′36″S 115°56′1.6″E / -31.97667, 115.933778 Cheers. SeanMack 14:38, 17 June 2007 (UTC)

Nycticorax caledonicus? Not sure. Dr_Dima.
The colouring seems to match but the neck and body shape doesn't seem quite right. [2]

SeanMack 15:19, 17 June 2007 (UTC)

Looks like N. caledonicus. It's a heron, so it spends most of its time with its neck tucked up like in most of the google image search photos, but can stretch it out to get a better view etc. --YFB ¿ 15:24, 17 June 2007 (UTC)
Thanks guys! SeanMack 13:11, 18 June 2007 (UTC)


[edit] Viral proteins with cleavage

I have a little question that has been bugging me the last couple of days. I can't for the life of me find anything on the cleavage site of hemagglutinin (from the avian influenza virus). I know that changes in the cleavage site have something to do with the virulance of the avian influenza virus. But there's nothing, I mean nothing to be found on the function of this site other than it gets cleaved at some time, somewhow, by something . I tried pubmed but that just gives me endless lists of articles on how the structure of the cleavage site differs between various AI strains. So if anyone can help me along it is greatly apreciated.PvT 15:09, 17 June 2007 (UTC)

You may find this short summary from PNAS illuminating. Bear in mind that it's nine years out of date now, so our understanding has probably been refined since then. Nevertheless, the basic principles are thus:
  • Hemagglutinin (HA) must be cleaved into two subunits (HA1 and HA2) in order to function.
  • This cleavage is carried out by trypsin-like serine proteases which bind to and cut HA at a basic amino acid residue (usually arginine).
  • Typically, the cleavage site is specific for one or only a few proteases; this allows the virus to replicate in only those cells that express those particular proteases. (In humans, those proteases are largely limited to the epithelial cells of the respiratory tract.)
  • Sometimes a mutation will occur which inserts additional basic amino acid residues into the area flanking the cleavage site. (The PNAS article I linked suggested an arginine/lysine-rich four-residue sequence of R/L-X-R/L-R.)
  • In virus particles with this mutation, a much wider range of proteases can now cleave HA into its functional components. This probably allows for faster synthesis of new virus particles (a faster cleavage step) and also (more insidiously) allows the virus to replicate in other tissues.
So the scary part of the avian flu (at least, the frightening strains) is that HA can be cleaved by a wide variety of ubiquitous proteases—which is probably why you're having difficulty identifying the specific protease involved. For specific proteases, you may find it useful to search PubMed using terms like 'hemagglutinin cleavage' and then (this is the important bit) click on the 'Review' tab (rather than 'All') to see only review articles. With any luck, one will summarize and link to all the seminal work in the field. TenOfAllTrades(talk) 18:58, 17 June 2007 (UTC)
your help is much much much apreciated. Thank you.62.194.90.107 19:29, 17 June 2007 (UTC)

[edit] TV set power supplies

In tv sets (the CRT-type, that is), at least in Europe the power supplies are often designed in such a way that the output is not galvanically separated from the mains input. Is this only a matter of reducing cost (although this does call for more sophisticated chassis design, galvanic separation of the antenna input, etc), or are there other advantages, for example related to grounding? /SvNH 16:17, 17 June 2007 (UTC)

They do this to reduce costs. A transformer is quite expensive compared to other components. Grounding is not achieved as the mains power leads are not grounded, but can float around depending on the neutral return current. I would expect that safety standards would not allow this any more. GB 03:10, 18 June 2007 (UTC)

Thank you. As for grounding, the neutral (or the phase conductor, for that matter) is not exactly floating with respect to earth - it always has some defined potential (wildly varying, probably). I thought this might help to avoid electrostatic charge build-up etc. but I am mostly speculating. /SvNH 15:54, 18 June 2007 (UTC)

[edit] How would you go about purchasing a meerkat if you really wanted one?

If you were serious about getting a meerkat, what do you have to do? Hope Clark

Meerkats live in large groups - it would probably be unhappy by itself. I don't think it would make a good pet. SteveBaker 17:04, 17 June 2007 (UTC)
Obviously it's going to depend on where you live, but also, many places (this is common in the US, anyway) have legal restrictions on ownership of wild animals. It's possible you'd need a special permit to do it legally, and of course there's no guarantee you could get a permit for such a thing. Friday (talk) 17:11, 17 June 2007 (UTC)
If you have any business owning a wild animal like that, presumably you can buy it from the same place that sells you the rest of your zoo animals. If you're still not sure, ask a fellow zookeeper. --TotoBaggins 19:05, 17 June 2007 (UTC)
It appears to be very difficult to get the right to keep a meerkat in the US even for zoos and would almost definitely be impossible to do so legally if you just wanted one as a pet [3]. I suspect the situation would be the same, in fact probably much more difficult in most other western countries... You might want to follow the suggestion of the page I linked and adopt a meerkat instead. Nil Einne 19:48, 17 June 2007 (UTC)
I suspect the best way to legally own a meerkat is to start a zoo. How serious are you? —Pengo 04:06, 18 June 2007 (UTC)

[edit] Effect of people on FM reception

OK, so we've had the furore about mysteriously dying lightbulbs. Now, can anyone explain to me why it is that, under certain conditions (what, I'm not exactly sure, but it seems to depend on the orientation of the aerial and whether or not the window is open [!]) I often find that I cannot get any FM reception on my hifi - there's just loads of harsh static - but that if I stand in a particular place in the room (not touching any of the radio components etc.) with my arms in a particular position, the reception comes back? With the right initial conditions, this is 100% repeatable - I can stand there and raise and lower my arm, and the signal will vary in direct response. I sometimes listen to the radio while I'm trying to go to sleep and I once found that I could only get a signal if I lay on one side of the bed, with my head facing to the left, and not in any other position. There is obviously some scientific explanation for this, but I'm puzzled as to why I seem to have such a strong effect on FM waves :/ --YFB ¿ 19:21, 17 June 2007 (UTC)

The human body, as with any solid object, affects radio waves in a number of ways. For example, I have a RF wireless remote (ATI Remote Wonder), that works better when you point it at yourself, probably because you're acting as an antenna. My physics is too rusty to say what's going in in this case, but it could have something to do with the diffraction Nil Einne 19:45, 17 June 2007 (UTC)
There is nothing mysterious about it. Any conductive material influences or even blocks the transmission of waves. FM is transmitted at around 100 MHz which corresponds to three meters wave length. The human body is a mediocre conductor and hence attenuates electromagnetic waves, but only a little bit. (See skin depth for the math.) Still, this influences the near field receiving pattern of the anntenna, and if the reception is bad anyway, is may get knocked out completely. Or, the other way round, the body might reflect or refract the waves to the antenna, improving reception. Finally, for devices with short antennae, the human body may be a goodextension of the antenna when you touch it. Simon A. 20:28, 17 June 2007 (UTC)
Before there was radio communication, physicist Heinrich Hertz found that high frequency electromagnetic waves could be reflected and bent by metal reflectors and solid lenses or prisms. It is not surprising that the human body has a similar ability to bend or reflect radio waves. This at least is a very replicable phenomenon. Edison 20:38, 17 June 2007 (UTC)
Thanks guys. I had a feeling it'd be to do with reflection/refraction. Good answers. --YFB ¿ 02:22, 18 June 2007 (UTC)

[edit] Where will alien life forms be put in the Linnaean taxonomy?

If we get around to finding alien life forms (presumably intially bacteria of a kind), where will they likely be put in the Linnaean classification system? In a new kingdom or existing ones? Best username yet 20:06, 17 June 2007 (UTC)

our article on Astrobiology gives over 50 internet links. I would start looking there for a serious answer. As for the kingdom, that would depend a great deal on the degree of genetic and biochemical similarity between the alien and terrestrial life forms. Panspermia would result is some similarity at least. Independent evolution OTOH may be convergent, producing life forms that appear similar to the terrestrial ones, but differ fundamentally on molecular level. On a lighter side, our Xenomorph (Alien) article describes the said alien as Internecivus raptus or Linguafoeda acheronsis, Linnaeus or not ;). Dr_Dima.
I'm too lazy. I wouldn't ask you to do it, as presumably you have better things to do, but does anyone else want to look through these links? Best username yet 21:19, 17 June 2007 (UTC)
not me, thank you Bendž|Ť 22:16, 17 June 2007 (UTC)
Presumably, if they weren't related to other living things on Earth, we'd have to give them a whole new branch on the tree of life, and we'd have a new highest rank (above domain) that divides life simply into "Earthly" and "alien". —Pengo 03:44, 18 June 2007 (UTC)
Yeah - I agree - since the tree is supposed to show evolutionary closeness they ought to be in completely separate branches. Unless of course life came to that planet and to earth via panspermia from a common source - but even in that case, this would have to have happened an awful long time ago and our most recent common ancestor would probably be so far back that you'd still put them on a separate branch. SteveBaker 04:45, 18 June 2007 (UTC)

[edit] Help understanding a simple circuit

I was helping a friend with this circuit (explanation here). It's been a long while since I did anything to do with circuits so perhaps I should have searched first. But am I right that the reason for the connection between Vcc to ground with the 1k resistor in parallel with the gate is to limit the current that will flow thru the gate? Cheers Nil Einne 20:57, 17 June 2007 (UTC)

Yeah, basically it's a pull up/pull down resistor set up. Best username yet 21:08, 17 June 2007 (UTC)
If you are talking about the five resistors on the left of the circuit then, no, they do not limit the current through the gate. Each one pulls the input of the gate down to ground when the switch is open (otherwise the input would be floating at an undefined voltage) - so it's a pull-down resistor. The switch, when closed, pulls the input of the gate up to Vcc. There is no danger of too much current flowing into the gate, whether or not it has a resistor, as long as its input remains somewhere between ground and Vcc.
On the other hand, the four resistors on the right of the picture do limit the current that flows out of the gate and through the LED. --Heron 21:46, 17 June 2007 (UTC)
Er, well you want to ground the gate when the switch is open. But if you directly ground it, then you can't pull it up by attaching VCC to it, right? So you need a resistor between it and ground, so the voltage goes up and down depending on whether the switch to VCC is open or closed. Gzuckier 18:33, 20 June 2007 (UTC)

[edit] Are tea and coffee harmful to parrots?

I'm thinking specifically of the Sun Conure. My new bird has shown an interest in my drinks. I know that booze is a no-no but what about caffeineated drink? --84.68.116.31 21:38, 17 June 2007 (UTC)

Ask a vet. Or trust your pet's natural instincts. It has evolved in the neotropics, where coffee is not found, so exercise caution. Offer it a coffee bean first, as it's more likely to know what it is and whether it's healthy and see how it goes. Then your feathered friend can start sharing your brew in the morning. Try cacao beans, which are closer to home, to see whether mocca is verboten. Or ask your vet. Bendž|Ť 22:24, 17 June 2007 (UTC)

p.s. None of that is a good idea.[4] Bendž|Ť 22:31, 17 June 2007 (UTC)

  • I point out that the suggestion "Or trust your pet's natural instincts. It has evolved in the neotropics, where coffee is not found" is self-contradictory. If the bird evolved where coffee is not found, there is no natural reason for it to have developed any particular instincts regarding the stuff, and therefore any instincts it does have will have arisen by chance (the coffee bean resembles some other bean, say) and cannot be trusted. --Anonymous, June 18, 04:15 (UTC).
This is why I suggested caution... caffeine-like substances are found in other plants, e.g. guarana, which is neotropical. Bendž|Ť 09:59, 19 June 2007 (UTC)
I did a little searching around, and I did find a veterinary forum where a member of the American Board of Veterinary Toxicologists said that she had seen cases of agitation and elevated heart rate in parrots that have eaten coffee beans. So no, it's not a good idea. --Joelmills 22:45, 17 June 2007 (UTC)
Isn't that what caffeine does, by its very nature? I've seen a few people state that alcohol is toxic to birds - which isn't necessarily true. It's 'toxic' in the sense that it has the same effect on birds as it does on humans - i.e. they get drunk and fall over if they have too much. They can definitely metabolize the stuff though - wild birds are known to seek out rotting, fermenting apples to eat and get rat-arsed off of. I believe that this was discussed here a few months ago. --Kurt Shaped Box 22:56, 17 June 2007 (UTC)
True, but since little is known about how birds metabolize caffeine (at least little that I could find), a safe dose is not known. --Joelmills 01:47, 18 June 2007 (UTC)

[edit] Fabric softener

Hello. Does fabric softener prevent static electricity by making the different fabrics in the clothes dryer "closer to one another on the electrostatic series"? Thanks. --Mayfare 23:05, 17 June 2007 (UTC)

[edit] Science Organizations

I'm a high school student primarily interested in physics and I was wondering if any of you had information about good extracurricular science organizations. I'm especially looking for something where I would get to socialize with other kids in the organization, but anything that looks good on a resume is fine. Thanks in advance. Imaninjapiratetalk to me 00:00, 18 June 2007 (UTC)

Where would you like to go to participate in your extracurricular science organization? --Mayfare 00:14, 18 June 2007 (UTC)
I live in southeastern Wisconsin, so anything in the area (Madison, Milwaukee, Chicago) would be great. Imaninjapiratetalk to me 00:45, 18 June 2007 (UTC)
I don't know what groups are in your area, but almost anything in engineering, math or the sciences will look good on a resume. When I was in high school, the only option was an engineering club. It mostly competed buiding robots and also happenned to organize teams for some mathematics competitions. Both types look good on a resume, but it's always nice to demonstrate that you're able to build something, as that's usually a vital skill that doesn't really show up on a transcript. Ask your teacher, find out what's available, and don't pick something that'll be a chore. — Laura Scudder ☎ 00:40, 18 June 2007 (UTC)


Science Olympiad is a popular organization. Your high-school may have a team; or you can start one. Nimur 10:38, 18 June 2007 (UTC)