Wikipedia:Reference desk/Archives/Science/2016 December 25

= December 25 =

Condoms failing during perfect use
What causes condoms to fail during perfect use? — Preceding unsigned comment added by Uncle dan is home (talk • contribs) 04:46, 25 December 2016 (UTC)
 * Define "perfect". ←Baseball Bugs What's up, Doc? carrots→ 15:07, 25 December 2016 (UTC)
 * Why does the OP need to define perfect? Perfect use is a standard wording for contraceptive research. It's reasonable to assume the OP is simply interested in perfect use as defined in these studies. I'm not sure if their definitions are always totally the same, but there's no reason to think the OP feels the need to limit it to one specific definition, and it's not like there's some sort of major disagreement over what's perfect use. Nil Einne (talk) 16:08, 25 December 2016 (UTC)
 * There's no such thing as "perfect". And your comments assume a number of facts not in evidence. StuRat raises a question below which you need to answer, as it's clear "perfect" is NOT universally understood for this product. ←Baseball Bugs What's up, Doc? carrots→ 16:17, 25 December 2016 (UTC)
 * What facts aren't in evidence? Nil Einne (talk) 16:21, 25 December 2016 (UTC)
 * "Perfect use is a standard wording for contraceptive research." Says who? "It's reasonable to assume the OP is simply interested in perfect use as defined in these studies." Says who? "It's not like there's some sort of major disagreement over what's perfect use." Prove it. ←Baseball Bugs What's up, Doc? carrots→ 16:25, 25 December 2016 (UTC)
 * The simplest answer is if you don't understand a question because you have zero understanding of the subject matter, it's best not to even try to answer. I suggest you give a read of Birth control and Comparison of birth control methods before you ever touch a question relating to contraception ever again. Nil Einne (talk) 16:29, 25 December 2016 (UTC)
 * I've been around the block a few times, and I know plenty about contraception. ←Baseball Bugs What's up, Doc? carrots→ 20:10, 25 December 2016 (UTC)
 * P.S. Even before my answer above, I've already proven all which you asked which I reasonably can with the references I provided below, especially . I obviously cannot reasonably prove that the the OP is interested in standard terminology used throughout contraceptive research rather than some weird BB or StuRat terminology, only the OP can do that. However I continue to assert that when standard terminology is being referred to, it's reasonable to assume that it's what someone is interested in, unless they give some evidence to the contrary Nil Einne (talk) 16:33, 25 December 2016 (UTC)
 * P.P.S. I should also clarify I used the term contraceptive research loosely. I was intending to include research relating to barrier methods to help reduce STI transmission, since perfect use applies to both of them. Nil Einne (talk) 16:59, 25 December 2016 (UTC)
 * (EC)What facts aren't in evidence? And I've already answered all of StuRat's questions. And why do you keep mentioning "perfect"? As I already said, this has nothing to do with "perfect" but "perfect use" which is an incredibly standard part of contraceptive research. Whether or not it's universally understood is a moot point. The question is whether the question can be understood without further clarification and the answer to that is it can be, since there is no need for any of us to define "perfect use" as it's a standard part of the research. If you want to understand what it means, you're free to ask without demanding people define a standard part of the research. Nil Einne (talk) 16:29, 25 December 2016 (UTC)
 * "Used according to directions" works. "Perfect use" is an absurdity. ←Baseball Bugs What's up, Doc? carrots→ 16:56, 25 December 2016 (UTC)
 * Yet the fact remains, it is a standard part of research and discussions surrounding contraception and methods to reduce STI transmission during sex. Probably at least partially because saying that Coitus interruptus or Fertility awareness was "used according to directions" is weird. In any case, the main point is if you disagree with the standard terminology that's up to you, but there's no reason to ask the OP to define something which is part of the standard terminology. Nil Einne (talk) 17:12, 25 December 2016 (UTC)
 * BTW, another factor would likely be "who's directions"? A person following their brother or poorly informed abstinence-promoting sexual educator may be following directions surrounding condom use. But if this directions are flawed they wouldn't be regarded as having perfect use. Nil Einne (talk) 17:49, 25 December 2016 (UTC)
 * The directions on the package. ←Baseball Bugs What's up, Doc? carrots→ 20:07, 25 December 2016 (UTC)
 * Next I suppose some clown will tell us that lots of specialties' jargons include phrases that don't mean exactly what a layman might take them to mean. —Tamfang (talk) 18:39, 25 December 2016 (UTC)


 * Assuming adequate manufacture, friction. Ian.thomson (talk) 04:49, 25 December 2016 (UTC)


 * Doesn't "perfect use" include lubricants ? StuRat (talk) 14:46, 25 December 2016 (UTC)


 * A manufacturing defect. StuRat (talk) 14:45, 25 December 2016 (UTC)
 * What lubrication are you using that completely eliminates friction? (And you do realise that for many people, such a wondrous substance isn't actually desired since it somewhat defeats the purpose of sex.)
 * Anyway this source has info on an often quoted figure of 2% failure for perfect use. It mentions only one study  which tried to look at perfect use. Perfect use is described as removing anyone who did not correctly follow condom usage instructions, they give an example of these specific errrors
 * "they put the condom on after starting intercourse; did not store the condom in a cool, dry place; did not push the air out of the condom tip; used an oil-based lubricant; did not hold on to the condom ring during withdrawal when the condom was intact; or did not withdraw while the penis was still erect."


 * Note while avoiding oil lubrication is mentioned, no where does it mention a need to use super lubrication which completely eliminates friction. While I assume the list isn't intended to be exhaustive e.g. poking holes in the condom before use probably wouldn't be considered following instructions. But I think it's fair to assume if external lubrication was required in their instructions, such an error would likely have been mentioned. So the lack of "did not use a water-based lubricant" or "did not use a condom-friendly lubricant" anywhere suggests it wasn't.
 * (The actual instructions on condom use that they provided to participants aren't in the paper. I suspect it was too long and in the early days of online publishing they couldn't include it as an extra to the online version.)
 * Nil Einne (talk) 16:21, 25 December 2016 (UTC)
 * Spermicidal foam is a pretty good lubricant and it's also another layer of defense in case of breakage or misuse. ←Baseball Bugs What's up, Doc? carrots→ 16:19, 25 December 2016 (UTC)
 * I've made some minor changes to my comment, but it doesn't seem to matter since your comment did not relate to mine. Nil Einne (talk) 16:21, 25 December 2016 (UTC)
 * To clarify, I have no idea why you suddenly bring up spermicidal foam. It relates to nothing I said even before my modification, nor to anything that StuRat said, nor to anything the OP said. The OP's question related to the causes of condom failure during perfect use. StuRat claimed that lubrication would eliminate all friction and was a requirement for perfect use. I pointed out the former made no sense and later does not appear to be correct.
 * You keep saying "prove it" and "define this" but then make a comment which poorly worded and I'm pretty sure poorly supported. While I mentioned 2% failure rate above, I mistakenly didn't properly clarify that I was referring to contraception. (Although this could be established by reading the sources.)
 * However condoms are also use to reduce the risk of STIs and the OP simply referred to failure rather than why they were interested in failures. In my case it was largely a moot point (the issue was that study did not appear to require lubrication for perfect use). But in your case, it's quite important as our article mentions, spermicides may actually increase transmission of some STIs. Yet no where did you say "another layer of defense in case of breakage or misuse" only applied to certain cases.
 * Also as our article mentions, the use of spermicide lubricated condoms over normal condoms is not advised by a number of authorities even for contraceptive purposes. It barely address the use of additional spermicidal foam lubrication for contraceptive purposes. (It makes a weak claim "Combined methods....believed....either method alone with a 1991 ref.) But IIRC from previous research which you can probably find in the archive, the evidence is weak enough for any real benefit that few authorities suggest it for use with condoms even without STI concerns. Yes IIRC isn't the best standard, but the only reason this arises is because you suddenly brought up spermicidal lubricant and made the claim they are beneficial without evidence.
 * Nil Einne (talk) 16:59, 25 December 2016 (UTC)
 * P.S. I initially intended to address StuRat's manufacturing defects claim but later abandoned this amongst other reasons, because I was incorrectly reading StuRat's posts as combined. This is mostly the reason why I failed to clarify I was referring to contraception and also indented my post to the wrong StuRat post. Apologies again. Nil Einne (talk) 17:12, 25 December 2016 (UTC)
 * Okay found it there Reference desk/Archives/Science/2015 February 5. It looks like I was mostly looking for evidence relating to spermicidal lubricated condoms and I didn't find much evidence. I believe, but can't be sure, I would have mentioned if I'd come across evidence that additional spermicide lubrication (as opposed to lubricated condoms) was beneficial which suggests to me I didn't. This was 2 years ago, and maybe I simply missed something. So if you have research suggesting using additional spermicide foam with condoms is beneficial for contraception (or anything else), I'm all ears. As I sort of implied there, one factor may be that the considering the possible increase in STI transmission risk and the probable? very minor benefit for contraception, it's of limited interest so little quality research. Remember per my earlier links, there's only 1 study of sufficient quality which actually looked at perfect use of condoms so it's not like this would be a unique situation. (Although it's true that perfect use generally gets far less interest than typical use.) Incidentally, t may be helpful to link to Nonoxynol-9 as it also has some info. Why you felt spermicidal foam was helpful info for this discussion, I still don't know, but whatever. Nil Einne (talk) 17:49, 25 December 2016 (UTC)


 * I did NOT claim that lubricants remove all friction. The lubricant doesn't need to completely eliminate friction, only bring it down to a level the material can withstand, for the designed duration. StuRat (talk) 17:49, 25 December 2016 (UTC)


 * But you said 'Doesn't "perfect use" include lubricants' in reply to an earlier point about friction being the cause of failures when manufacturing defects weren't involved. Unless you're claiming they will eliminate friction, this is irrelevant since friction is most likely part of the cause of failures (whether breakage or slippage), for that matter likely including many cases of defective condoms. My bigger concern is when both your posts were read in combination, this may lead to the false conclusion that manufacturing defects are the most likely cause of failures with perfect use. As far as I can tell, this isn't the case. (I did have some research for this but abandoned it partially because it wasn't as clear cut as I would like and also because as mentioned above I decided your answer was fairly ambiguous and I couldn't be bothered dealing with it.) Condoms may fail even with perfect use and without defects simply because basically sex involves friction and so this can lead to breakages and slippage. And yes this could happens with any normal lubrication used in sex. If you weren't intending to suggest that, well that's fine but there's still no explanation for your post about lubrication. Nil Einne (talk) 18:09, 25 December 2016 (UTC)


 * Let's compare with a car engine. Run without oil, it will break down immediately.  With the proper oil (and all the other required maintenance), it should run for it's design life (say 100K miles), unless it has a manufacturing defect.  None of this implies that engine oil removes all friction.  Condoms are similar, in this respect. StuRat (talk) 20:39, 25 December 2016 (UTC)

Vocal type
If one's vocal range is D2-A4, what voice type is that (in both sexes)? Languagesare (talk) 10:10, 25 December 2016 (UTC)
 * It is really impossible to answer this question with just this data because the range is not simply determined by your highest or lowest notes, but by a multitude of factors. Ewa Podleś has a three-octave range (spanning, IIRC, from about C3 to C6), but she is a contralto, because, as she has "a range of more than three octaves, high notes like a soprano, low notes like a real alto, as well as the technique to sing coloratura" (as she puts it). Perhaps some of this thinking, which is rather common, comes from how things tend to work in most community choirs, where the bar for getting the part is very low and is just "is it within your range", even if the timbre is completely wrong. What you also need to consider is tessitura (where you are most comfortable singing) and timbre.
 * It's probably safe to assume you are male, because this range is practically impossible for females. That cuts things down from the usual seven we give in vocal range to the lowest three, since you can't go into the fifth octave. Beyond that, it gets impossible to cut things down further unless we know where your most comfortable range is, and in general how your voice sounds throughout all the two and a half octaves you give.
 * (I should note also that I am looking at it from a classical perspective, which is the only one I actually experienced. Things may be different in other genres.) Double sharp (talk) 10:34, 25 December 2016 (UTC)

Thanks for your very thorough answer. My most comfortable range is F2-F4, the low notes are strong but as I go higher it becomes childlike. Languagesare (talk) 11:54, 25 December 2016 (UTC)
 * The childlike tone you speak of past the break (I presume around E4 or so) suggests falsetto, so I'd be willing to bet that you're a bass, given the strength of the lowest notes, going down to F2 and a little beyond. (But please take it with a pinch of salt, because my accuracy would be impaired by not being able to hear you. If you want to know for sure, I'd suggest going to a qualified singing teacher in person.) Double sharp (talk) 12:34, 25 December 2016 (UTC)


 * During a lesson in a boys' school the music master asked all the boys to sing and then told them the classification of their voices.  When he reached one he didn't much like he listened to him sing and then said "contralto". 86.185.150.23 (talk) 12:25, 25 December 2016 (UTC)
 * LOL! It's a range that never gets any respect, to be sure. Double sharp (talk) 12:34, 25 December 2016 (UTC)

Snow References
Good morning, Science Reference Desk! Good evening, for any readers who happen to be elsewhere! (As far as I'm concerned, it's going to be morning all week today)!
 * To enhance our encyclopedia's coverage of snow and to preemptively answer any impending questions about snow, here are a few science references that will be helpful to our regular readers:
 * Six Snow Forecast Tools from the U.S. National Weather Service
 * The Snow Data System from NASA Jet Propulsion Laboratory
 * For our regular readers who happen to be in the southern hemisphere of our planet for some reason, fear not: here are some more scientific references to help you find snow:
 * Alpine Areas District Forecast, from the Bureau of Meteorology...
 * And for our readers who have more distant snow objectives, here is the best snow data I can find for Mars, and here are some lithographs of Enceladus and ...a slightly less scientifically-accurate lithograph of Cassini.
 * Nimur (talk) 14:13, 25 December 2016 (UTC)

In chemistry are there 3 states of matter or 4 or 5?
I've read in a book ("chemistry for dummies") that there are 3 states of matter: Gas,Liquid, and Solid. No mention about coloid (gel). Then is the coloid (gel) not considered as state by itself? In my school, if I'm not mistaken I learnt that the coloid is state by itself. Here in wikipedia I saw another state: plasma.so now I'm confused how many states there are in fact. 93.126.88.30 (talk) 15:57, 25 December 2016 (UTC)


 * See List of states of matter - which does not include colloids as those are mixtures of solid and liquid. The traditional fourth state is plasma - but modern physics has expanded the list considerably. Wymspen (talk) 16:18, 25 December 2016 (UTC)


 * Those are the 3 most common states of matter. There are also some truly bizarre states, like a Bose-Einstein condensate. StuRat (talk) 17:54, 25 December 2016 (UTC)


 * Different phases are defined using the Gibbs free energy, if going from one thermodynamic state to another there is non-analytic behavior in the Gibbs free energy, then we say that the state correspond to different phases. The idea is that all the properties of some compound in some phase can be obtained by measuring it in the neighborhood of some point. E.g. the heat capacity of water at 55 C can be determined with arbitrary accuracy by measuring it and a large enough of its derivatives at, say 10 C. These derivatives can be obtained by measuring the heat capacity in some interval around 10 C, so it boils down to making a large enough number of measurements near 10 C. And this will always work for any property (expansion coefficient, compressibility viscosity, thermal conductivity etc. etc.) for any chemical compound, as long as the measurements are taken in the same phase as the point where you want to make the prediction. This is then true by the very definition of phase. So, whenever this breaks down the phase is different, this can be because in one phase the compound is a liquid and in the other it is a gas, but there are a huge number of other phase transitions, e.g. carbon can be in graphite form or in the form of diamond. Water can be a solid in a large number of different types of ice.


 * In many cases the different phases can exist at the same temperatures and pressures. One phase is then metastable, in thermal equilibrium the Gibbs free energy should be a minimum so the phase with the larger Gibbs free energy is then in the metastable phase. Water slowly heated in a microwave can be heated to above the boiling point without it turning into steam. The properties of this superheated water are then what you would have obtained from extrapolating the Gibbs free energy of water below the boiling point. Similarly, if you take the Gibbs free energy of steam and extrapolate it below the boiling point, you get the Gibbs free energy of super saturated water vapor instead of water. Count Iblis (talk) 19:35, 25 December 2016 (UTC)


 * ... but don't we need to distinguish between state, phase, mesophase and allotrope? ( ... not to disagree with the above, but just to avoid confusing the OP. )    D b f i r s   20:48, 25 December 2016 (UTC)


 * Plasmas don't come up very much in chemistry, because of the dissociation of molecular bonds in them. Double sharp (talk) 04:26, 26 December 2016 (UTC)


 * They actually do come up quite a number of times in industrial chemistry, for example during the synthesis of acetylene. 2601:646:8E01:7E0B:F88D:DE34:7772:8E5B (talk) 07:08, 26 December 2016 (UTC)


 * True; I misspoke. What I meant is that while they may be useful as intermediates to produce something else, their actual chemistry is not very significant. Double sharp (talk) 12:17, 26 December 2016 (UTC)


 * The definition of a "state of matter" is more about language than it is about reality. Wymspen pointed you to List of states of matter. As you can see, you can categorize the more exotic "states" in several ways. Depending on your field of study, you may find it easier to think of it as "solid, liquid, gas, other", and then expand "other" by specifying the actual conditions. -Arch dude (talk) 07:16, 26 December 2016 (UTC)

The differences and the definitions of proton and neutron
It's used to say the definition of proton and neutron are that the proton is electrically charged while the neutron is not. My question is if we can put another distinction and simply say: neutron is the heavier particles of the nucleus, while the protons are the lighter particles of the nucleus (electrons are indeed the lightest but they are not in the nucleus). If that's ok, then why it's not in use? (always I see the definition about the electrical issue only) 93.126.88.30 (talk) 20:43, 25 December 2016 (UTC)


 * The chief distinction is the charge (combination of quarks), with the difference in mass being incidental and less important in nearly all applications.   D b f i r s   20:52, 25 December 2016 (UTC)


 * The key thing to understand here is that a chemical element always has the same number of protons. For example, three protons make lithium, no matter how many neutrons are present - the neutrons only decide whether you have a radioactive form of lithium or not.  (as in isotopes of lithium)  Incidentally, that article describes a nucleus where one of the neutrons was replaced by a lambda baryon, which is much heavier... so it's not strictly speaking only two building blocks (plus gluons) available. Wnt (talk) 02:35, 26 December 2016 (UTC)
 * Those are hypernuclei. Indeed a few containing lambdas are known, and there have been efforts to detect others with sigmas or xis, which would presumably make a five-dimensional nuclide chart. Double sharp (talk) 03:10, 26 December 2016 (UTC)
 * It's curious - I found myself looking up "stable hypernucleus" and found /, but I'm far at sea there ... could empty a pistol into that paper and not a shot would get past the first page, I'm afraid. I know an unstable subatomic particle (the neutron) can be made stable in the right nucleus; is the same true of hyperons?  I can think of a name for a stable lithium hypernucleus already. :) Wnt (talk) 23:11, 27 December 2016 (UTC)
 * From the first page of the first one: "Multistrange hadronic matter in finite systems and in bulk is predicted on general grounds to be stable, up to strangeness violating weak decays." So, there is that caveat, which has apparently not yet been investigated. Though there are nevertheless some predictions that they might be absolutely stable, as cited in your second paper. This would be very cool if not for the problem of making enough! Double sharp (talk) 03:24, 28 December 2016 (UTC)
 * BTW the coolest thing is that all the strange hyperons have half-lives well beyond 10−14 seconds, which is the theoretical limit for chemistry (you need that long for all the nucleons and hypernucleons to arrange themselves into shells)! So we may be able to chemically investigate some of these someday! Double sharp (talk) 13:46, 30 December 2016 (UTC)


 * For the chemist, the charge/non-charge is paramount. For a deeper observer, a more nuanced definition may be needed. However, if you need a more nuanced definition, you are already past the simple charge/no-charge definition, so you must think in terms of the quarks, and the mass difference is a minor consideration. -Arch dude (talk) 06:59, 26 December 2016 (UTC)


 * I think these answers are missing the point. By asking about definitions, the original poster seems to think that by "proton" we might mean any positively charged particle found in the nucleus, and it just happens that there is only one particle like that.  Rather, we have observed that there is a certain kind of particle that is found in the nucleus, and it has certain properties of charge, mass, and being made of a certain combination of quarks.  We have named this particle the "proton".  In doing this we aren't focusing on any one property of it; we're assigning a name to the particle with the whole combination of properties.  (And similarly for "neutron", of course.) --69.159.60.210 (talk) 10:23, 26 December 2016 (UTC)


 * The two major differences between neutrons and protons is their mass, and that free neutrons (not bound in a stable nucleus) decay with a halflife of about 15 minutes, while protons are believed to be stable. If they decay, the halflife of proton decay must be on scales dwarfing the current age of the universe.


 * Free neutron decay results in the production of a proton (that is, one of the neutron's quarks changes nature), an electron, conserving the charge, an antineutrino, and in some cases a gamma ray. See the linked article for details.
 * μηδείς (talk) 23:55, 26 December 2016 (UTC)
 * Yes, to enlarge on the OP's viewpoint - afaiu he is right to think that electric charge is not always the most salient thing for all purposes. Thinking of the proton & neutron as nucleons bound by the Nuclear force as he does was the historical route of people like Hideki Yukawa, and as Nuclear force says, "The nuclear force is nearly independent of whether the nucleons are neutrons or protons." Also: "This property is called charge independence." - a welcome case of sensible terminology.:-) John Z (talk) 03:23, 27 December 2016 (UTC)