Wikipedia:Reference desk/Archives/Science/2010 September 12

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September 12

Density of methane clathrate and formation thermodynamics

Why is the article on methane clathrate so unhelpful and only giving one sig fig for the density? It doesn't tell me whether methane clathrate is more dense or less dense than regular ice. Google doesn't appear to help because all the hits cite Wikipedia figures. -_-

See, I don't know why higher pressures should induce clathrate formation -- I mean, if it's less dense so shouldn't it discourage clathrate formation? John Riemann Soong (talk) 03:39, 12 September 2010 (UTC)

This paper shows a phase diagram for the system which may be helpful. Mikenorton (talk) 03:55, 12 September 2010 (UTC)

If you don't like our article on methane clathrate, you could always do a little bit of research and improve it... And as methane clathrate is about 1300 time more dense than gaseous methane, of course pressure would favour its formation. Physchim62 (talk) 12:28, 12 September 2010 (UTC)

Ooops, I guess I forgot there was a CH4 + water system -- I mean, so the ice sacrifices a little density for much improved density in methane? John Riemann Soong (talk) 17:17, 12 September 2010 (UTC)

TV

Do mini tvs use LDC screens, or cathod ray tubes? —Preceding unsigned comment added by Creivler (talk • contribs) 13:08, 12 September 2010 (UTC)

Modern handheld televisions use either LCD or OLED displays. The MTV-1, an early miniature television, is about as small as you can get with CRT technology. Gandalf61 (talk) 13:34, 12 September 2010 (UTC)

Hmm does the CRT really take whole length of the MTV-1? If not are you sure you couldn't shrink the length perhaps by about half with modern electronics? You'd still need capacitors and stuff I guess Nil Einne (talk) 13:08, 13 September 2010 (UTC)

Not sure about the length, it should be possible. Sinclair (1983) (and Sony (1982) too apparently) produced TVs with 'flat' CRT tubes, see Sinclair FTV1 and The short "history" of Pocket-TV - 220.101 talk^\Contribs 23:00, 16 September 2010 (UTC)

A little OR and we have this, which is a German language part of 'The short "history" of Pocket-TV'. Pictures show the guts of the MTV-1 and the CRT is about ¾ of the length of the case. 220.101 talk^\Contribs 00:43, 17 September 2010 (UTC)

Thanks for the links. With the internals it doesn't look like it would be quite so simple to shrink the MTV-1 much. However on a different tack, I wonder whether developments since the 1980s would enable the CRT to be made shorter? There must be things which could be done if you had the will and money. Cathode ray tube#Zeus Thin CRT Displays for example. Or you could use Surface-conduction electron-emitter display or Field emission display and call it a CRT I guess :-P A moot point of course since even these techs are dead for large screens, let alone small screens. And of course no one is going to want such a screen for a portable device when you can have an LCD or particularly an OLED. Nil Einne (talk) 11:12, 17 September 2010 (UTC)

Ants

When my worker ants die, why do they always lie on their backs with their legs in the air? I've noticed this in almost every death of my worker ants. Is it some evolutionary result of making the dead easier to carry and remove from my nest by the living workers? JennyTheQueenAnt (talk) 13:19, 12 September 2010 (UTC)

Species info would help if you have it. Are you watching them roll over, then die? Otherwise, I'd guess they die standing up, then get rolled over when their legs curl up (dessication/ rigor mortis?). But it could be an adaptive behavior. Some species will `intentionally' leave the nest when they are infected, so that their bodies won't be a source of further infection for the colony. SemanticMantis (talk) 14:02, 12 September 2010 (UTC)

There's a Straight Dope article about this issue with cockroaches. Paul (Stansifer) 13:13, 13 September 2010 (UTC)

Can I get pregnant even if i had a postinor 2 tabs( within 48 - 72 hours)

This question has been removed. Per the reference desk guidelines, the reference desk is not an appropriate place to request medical, legal or other professional advice, including any kind of medical diagnosis or prognosis, or treatment recommendations. For such advice, please see a qualified professional. If you don't believe this is such a request, please explain what you meant to ask, either here or on the talk page discussion (if a link has been provided). DMacks (talk) 17:31, 12 September 2010 (UTC)--DMacks (talk) 17:51, 12 September 2010 (UTC)

Even a doctor wouldn't attempt to diagnose a pregnancy based solely on the question posted. Some general information about the issues involved, followed by a recommendation to see a medical professional for an actual diagnosis and treatment recommendations, would be more helpful than "Go away!". Peter Karlsen (talk) 17:46, 12 September 2010 (UTC)

Feel free to discuss on the talk-page. DMacks (talk) 17:55, 12 September 2010 (UTC)

We can't give medical advice, but it would be remiss of us not to let you know that we have an article Emergency contraception#Types_of_ECPs that discusses Postinor-2 to some extent. Note: while vinegar was used as a sort of contraceptive in ancient times and in less developed countries, this has been denounced as a harmful practice.[1] It was perhaps best used by the ancients as a spermicidal soaking agent for a sponge, wool, etc. meant to shield the vagina, and has been used by others as a douche immediately afterward - in any case, I greatly doubt that drinking it by mouth is relevant to pregnancy in general. You may also wish to consult resources on the withdrawal method.[2] There are health forums online that entertain questions similar to yours.[3][4] Wnt (talk) 19:55, 13 September 2010 (UTC)