Wikipedia:Reference desk/Archives/Science/2013 June 26

= June 26 =

Homemade explosives, part 2
I've recently been re-reading the third part of The Gulag Archipelago, and it brought up a technical question: In the part describing the uprising at the Kengir (Dzhezkazgan) hard-labor camp, one of the defense measures taken by the zeki (inmates) was to make homemade bombs from sulfur and calcium carbide, with which they reportedly later knocked out one of the tanks sent in to suppress the uprising. My question is, can such a device really knock out any tank, or specifically a T-34? Or was that an erroneous report on Solzhenitsyn's part (or maybe even a misreading on my part)? (Note: by "knocked out", I don't mean a complete K-kill, but an F-kill or M-kill, which would still put the tank out of combat.) 24.23.196.85 (talk) 01:02, 26 June 2013 (UTC)


 * It's hard to tell without more information, but at least in concept it is possible: calcium carbide, acidified, with sulfuric acid or the like, produces acetylene, which can be burned with oxygen to make a cutting torch that could be used to slice apart the tracks on the tank and, eventually, even to open up the armor! :) An explosion of acetylene and air could also, in theory, launch the tank so far and fast up in the air that it would kill everything inside.  See also   Sulfur itself apparently reacts violently with carbides .  There may be important aspects of the chemistry I'm missing here.  My bet, however, is that they "knocked out" the tank by welding something together or melting it apart in a far more localized way than a true high explosive would do. Wnt (talk) 06:28, 26 June 2013 (UTC)
 * I'm not an explosive expert but I would bet you could make a pretty good explosive out of calcium carbide, capable of disabling a tank. It might take one or two more common ingredients other then sulfur, maybe like sodium peroxide, but perhaps the author is just being cautious and responsible by not providing a ready recipe for a home made bomb. If a grease covered sock with some tnt can do it ;) Vespine (talk) 06:44, 26 June 2013 (UTC)
 * Actually, the "just use some TNT" bit omits the detail of a blasting cap - I think that usually, the hobbyist/terrorist/freedom fighter finds that the most fearsome part, since a primary explosive is designed to go off with little provocation. Then again, TNT explosives predating IMX-101 and the like were subject to the possibility of going off by bullet or in a fire - I don't know how likely it was though. Wnt (talk) 18:38, 26 June 2013 (UTC)
 * Hit it in the right spot(s), and a tank can be surprisingly easy to 'take out' - more so if 'take out' refers to a mobility kill, firepower kill or mission kill as opposed to a catastrophic kill. You don't even need explosives to do it; during the Winter war the Finns took out Russian tanks with incendiary bottles, and during the Second Italo–Ethiopian War several Italian tracked vehicles were disabled by having their drive-trains jammed. WegianWarrior (talk) 06:54, 26 June 2013 (UTC)
 * My grandfather was in the Warsaw uprising, and frequently tells the story of the 14 year old kid who took out two tanks by getting close enough to put a petrol bomb in the right place and legging it (he looked young for his age, so the Germans didn't realise he was a combatant until too late). MChesterMC (talk) 08:31, 26 June 2013 (UTC)


 * It seems that the T34 remained vulnerable to petrol bombs; they were used in the 1956 Hungarian Uprising and were claimed to be effective. However, according to our Molotov cocktail article, there were tests with petrol bombs and the No. 76 Special Incendiary Grenades in 1940; "...trials on modern British tanks confirmed that Molotov and SIP grenades caused the occupants of the tanks 'no inconvenience whatsoever'." Alansplodge (talk) 19:29, 27 June 2013 (UTC)

What is the speed of sound in liquid diamond?
- and what does the stuff look like? - I fluctuate between imagining something like graphite and something like, well, liquid diamond...

Thanks Adambrowne666 (talk) 10:14, 26 June 2013 (UTC)


 * A phase change doesn't preserve a network solid's characteristics. Meaning, that there is no such thing as liquid diamond. Molten diamond is just molten carbon. Plasmic Physics (talk) 11:07, 26 June 2013 (UTC)


 * yeah, i was expecting someone to say this - thanks for the reply - I don't quite understand it either, but check out the link, and the original paper linked in the article - it seems if carbon is under sufficiently high pressure and temperature, scientists are happy to call it liquid diamond. Adambrowne666 (talk) 11:11, 26 June 2013 (UTC)


 * Perhaps it is a metastable phase consisting of nanodiamond fragments, like unsaturated adamantane with dangling bonds? Plasmic Physics (talk) 11:21, 26 June 2013 (UTC)


 * Here's a visualisation: a diamond is to carbon, as a windowpane is to glass. A molten windowpane is just molten glass. When you melt a windowpane, you compromise its shape, the completely liquid glass produced, does not contain bits of windowpane, nor does it consist of windowpane, though it originated as from a windowpane. Molten glass is the same, independent of the method used to prepare it, as long as the temperature, pressure, and recipe remains constant. So it is with molten carbon. Plasmic Physics (talk) 11:17, 26 June 2013 (UTC)


 * If the liquid is indeed a mixture of nanodiamond fragments, then perhaps carbon compares better to sulfur than to glass. Plasmic Physics (talk) 11:25, 26 June 2013 (UTC)


 * See diamondoid, to know what I'm talking about. Plasmic Physics (talk) 11:33, 26 June 2013 (UTC)


 * Is there no clue in the links provided? - I admit it's well beyond my understanding. Adambrowne666 (talk) 11:57, 26 June 2013 (UTC)


 * No, it seems like the journal article may have been misquoted. It seems like what they are talking about, is liquid carbon with diamondoids floating on top, not a single phase system with uniform properties. Just like an ice cube covered in dust. Plasmic Physics (talk) 12:12, 26 June 2013 (UTC)
 * Perhaps, this system reflects the freezing range that lies between the solidus and the liquidus. Probably, what is occurring, is that the freezing range expands with pressure, making the system less susceptible to pressure and temperature variations. As a result, it should be easier to maintain such a metastable state. Plasmic Physics (talk) 12:32, 26 June 2013 (UTC)
 * It follows that the study may assume that at a certain depth in those gas giants, a temperature and pressure exists that lie within the freezing range. Plasmic Physics (talk) 12:38, 26 June 2013 (UTC)
 * For the diamondoids to be differentiated from the liquid carbon, it is necessary for a freezing range temperature-pressure pair to coincide at the carbon-mantle interface. Plasmic Physics (talk) 12:43, 26 June 2013 (UTC)
 * The Nature paper linked from the phys.org article here talks about extending "the phase diagram of diamond", though I can only get the title and a small amount of the abstract. If someone with access could have a look, it would probably answer a lot of questions.  It may be that the final state is liquid carbon, but the phase changes to get there are heavily dependent on which allotrope is considered. MChesterMC (talk) 15:00, 26 June 2013 (UTC)


 * Here is a link to the abstract of the paper in question. It does not speak of "liquid diamond" -- it says that diamond melts at high pressure to a complex metallic fluid state. Looie496 (talk) 15:17, 26 June 2013 (UTC)


 * Harrumph. Carbon has a liquid-liquid phase transition   The high pressure phase is largely sp3 bonded, i.e. liquid diamond. Wnt (talk) 18:25, 26 June 2013 (UTC)


 * What molecules are formed that contains the sp3 bonding? Plasmic Physics (talk) 10:44, 27 June 2013 (UTC)

Thank YOU, Wnt! Adambrowne666 (talk)


 * So then, my post at 11:21, 26 June 2013 (UTC) is correct, except for the 'metastable' part? Plasmic Physics (talk) 01:40, 27 June 2013 (UTC)
 * What makes the presence of sp3 bonding so uniquely diamondine? Doesn't Lonsdaleite also contain sp3 bonding? Plasmic Physics (talk) 01:45, 27 June 2013 (UTC)


 * Yeah, good on you, Plasmic - but in the meantime, can we answer the questions please? - what are the properties of this stuff, whatever we want to call it?Adambrowne666 (talk) 05:12, 27 June 2013 (UTC)


 * I wasn't looking for praise, only confirmation. I needed to know that we're on the same page, so to speak. - fair enough - sorry Adambrowne666 (talk) 12:47, 27 June 2013 (UTC)


 * Well, it's not sp2 graphite.--Wikimedes (talk) 08:57, 27 June 2013 (UTC)
 * Um, I believe that for a single component system (i.e. carbon) there will be a freezing point rather than a freezing range for a given pressure.--Wikimedes (talk) 08:57, 27 June 2013 (UTC)


 * Reducing it to a single component system, because it contains only carbon is a false logic, because that would be neglecting the existence of bonds. Plasmic Physics (talk) 10:54, 27 June 2013 (UTC)


 * Interesting idea. Do you have an example of a (materially) single component system that exhibits a melting point range because different bonding types allow it to circumvent the phase rule?--Wikimedes (talk) 18:19, 27 June 2013 (UTC)


 * Sulfur. Plasmic Physics (talk) 23:06, 27 June 2013 (UTC)
 * Boron, Silicon, Phosphorus, Germanium, Arsenic, Selenium, Antimony, and Tellurium are all good candidates. Plasmic Physics (talk) 23:12, 27 June 2013 (UTC)


 * We're getting a bit far from the OP's question, so I've responded on your talk page.--Wikimedes (talk) 08:42, 28 June 2013 (UTC)


 * According to "the stability domain of lonsdaleite (hexagonal diamond) lies entirely within that of cubic diamond".  If that means what I think it means, then the liquid carbon would not adjoin on it directly, so it would be better described as liquid diamond; even if it did, it would still be "diamond" in the loose sense that lonsdaleite is "cubic diamond".  Wnt (talk) 12:10, 27 June 2013 (UTC)

Diplazium esculentum
Does anyone know if this fern has nectaries? Aaadddaaammm (talk) 12:48, 26 June 2013 (UTC)
 * The nectaries article you linked cites a recent review which probably sheds some light on whether it is one of the species . Unfortunately I can't access it right now either.  You (or anyone here who wants to be nice!) could take a request to WikiProject Resource Exchange or otherwise ILL it to get a copy.  Another approach would be to e-mail the author and ask, or ask for an electronic copy etc.
 * If you do, it would be great if you could copy out the list of species known to have them to the article. They can't copyright a mere list of species believed to have this feature.
 * Last but not least... when dealing with a group where a feature is widely present, it is very possible you could take a sample yourself under a microscope and find them (or some vestige thereof) even if they are not already known to exist, and actually make a research discovery! :) Wnt (talk) 18:33, 26 June 2013 (UTC)
 * I have a pdf of the article, email me if you want a copy. I'll be skimming it, looking for any lists I can paste here, and/or this particular species. SemanticMantis (talk) 18:52, 26 June 2013 (UTC)


 * Now, this is interesting. Our photo of a fern at Nectar (EFN) also appears in the Weber & Keeler article. Our photo is credited as "own work" from our own ref-desker user:Obsidian Soul (does linking like that give him a notification?). Perhaps s/he also contributed to that review article, or knows something of this matter? I hope at least that he can confirm he is the source of the photo.


 * Anyway, here's a list of clades/orders with known EFN (sorry for lack of formatting, it's a 4-col table)
 * The only fern clades mentioned in the article are Cyatheales and Polypodiales. Polypodiales does contain D. esculentem, via Athyriaceae, but neither genus nor family name occurs in the article. Fern EFN seem to be the exception, as 99.7% of known species are Angiosperms. Nevertheless, they were known to Darwin, and he seems to have been slightly wrong about them, see (Darwin F. 1877. On the nectar glands of the common brake fern. Journal of the Linnean Society of London (Botany) 15: 398–409.)
 * So, no conclusive answer from that article. The fern in question is in a fern order known to have EFN. I can't find any published source saying they do, but it's certainly possible. Best bet, as Wnt suggests, is to get a sample and a hand lens! SemanticMantis (talk) 20:06, 26 June 2013 (UTC)


 * Hi SemanticMantis, sorry for the delayed response. No, I'm not a botanist, heh, so no I didn't contribute anything to the mentioned paper. The authors however, contacted me a while ago for permission to use the picture, which I readily gave.


 * The picture is of a young Drynaria quercifolia frond with ants feeding on the EFNs. They are already pretty well-known in having EFNs. I can't find any sources however, that identifies Diplazium members as having EFNs. Neither on their closest related genera - Deparia and Athyrium.


 * D. esculentum, like the Drynaria quercifolia in my pic, are also pretty common around here (the Philippines), and I've never seen any of them attracting ants or anything like that, so probably unlikely.--  O BSIDIAN  †  S OUL  05:56, 29 June 2013 (UTC)

How much should it cost to replace the propeller shaft in my 2001 BMW 740i?
I was quoted nearly 1800 including 1200 or so in parts and 420 in labor plus tax and disposal fees, is this fair? Also I already signed the estimate I think, if I find another mechanic, do I have a way out?108.212.70.237 (talk) 13:45, 26 June 2013 (UTC)
 * Where are you and what currency are you working in? Generally when people don't bother posting their location, it's the US. Is that the case here? Also, isn't this probably better at Misc? 131.251.133.26 (talk) 13:48, 26 June 2013 (UTC)
 * It says science and technology and I am in Oakland, California and working in US dollars obviously.108.212.70.237 (talk) 20:52, 26 June 2013 (UTC)
 * As to "do I have a way out", that would be legal advice, which we can't help you with. You would need to talk to a lawyer in your jurisdiction.  Rojomoke (talk) 13:58, 26 June 2013 (UTC)
 * That's not what I said, I want to know which is information available about such matters which law or laws cover this theme are they federal financial laws or are they California state vehicle code laws? I am just asking for information not an answer.108.212.70.237 (talk) 20:54, 26 June 2013 (UTC)
 * The way to confirm an estimate is to find the part prices and the amount of labor involved. You can check online parts sites and call a BMW dealership for a part cost. The labor price sounds fair to me (in the US) - there is a decent amount of work involved, and they also rolled in disposal and taxes to that number. If you want to confirm it with a reference, estimator's guides are published that give labor time estimates - you could check with your local library to see if they have one available that covers your vehicle. $75/hr is a good low-end labor rate, so you multiply that by how many hours the guide suggests. 209.131.76.183 (talk) 16:08, 26 June 2013 (UTC)


 * re post aboove: Sounds like the OP went to a registered dealer who's charging him the book price. For a car that age he  might be able to google local owners club that know of back-street auto-shops that are both reliable and can do the same thing cheaper. Insistently: A prop-shaft is a pretty easy thing to replace oneself. If you don't know how to take out the circlips  with out circlip pliers then you might need to buy one of those but it really is a p-of-p. 420 in labour? If that's US dollars and not Honkong dollars or European Croners then I am in the wrong job – bring it over to me  and I'll do it for you. Mind you a auto-shop has loads of overheads so it bound to cost more. Do you have a way out? Have you left the car with them and have they started work on it  -if not then yes.--Aspro (talk) 16:24, 26 June 2013 (UTC)
 * Note that BMW's have a split prop shaft, with a carrier bearing between the two halves - like on trucks. There is not a single prop shaft as is typical with older US RWD cars.  On the 740i the uv joints are not attached with circlips.  BMW makes the whole thing, 2 prop shafts and uv joints as a single replaceable unit.  Also note that the price quoted may include other items the mechanic found appropriate.  This is the same OP that asked about vibration on mild acceleration a week ago, saying he had no cash.  Therefore, as explained then, the car may be a cheapy that has not been properly serviced.  Indeed prop shaft / uv joint failure will not happen if the car has been properly serviced since new.  — Preceding unsigned comment added by 120.145.9.177 (talk) 00:56, 27 June 2013 (UTC)


 * If those are new, original, BMW parts - bought from a dealership who has to make a profit on them - then probably that's the right price. But with something like a prop shaft, and for a car that old, you'd probably be better off getting a used one from a junkyard or something: This guy will sell you one for $150.  These guys have new ones for $630 and "remanufactured" ones for $450.  Labor charges are quite variable.  BMW dealerships charge around $600/hour here in Texas - I doubt you can change a prop shaft in much less time than that..."disposal fees" on a prop shaft shouldn't be significant.  A non-BMW garage would likely have lower labor rates - but with mechanics who are less familiar/trained with that car, it might well take them longer to do the job.  So I don't find the labor charge too unreasonable by US/Texas standards.


 * Good to hear that there are better part prices out there - I recommend that if the OP isn't comfortable doing the work himself, he should try calling around other local mechanics. Mention the part price online, and if the mechanic can't match it, see if they're willing to install it. Some mechanics require that they handle everything, and others allow you to bring your own parts. In my experience, $75/hr is a pretty common low-end rate, which makes the $420 be about 5 hours plus $50 for the taxes/fees mentioned. I don't know the details for doing the job on his car, but it doesn't seem unreasonable to me, especially for a non-BMW shop. 209.131.76.183 (talk) 17:24, 26 June 2013 (UTC)


 * As for whether you can get out of some agreement that you signed - that would be legal advice - and we're not allowed to give out legal advice here on Wikipedia. I bet if you asked them nicely to use a used or "remanufactured" prop shaft instead of a new one, they'd be OK with that. SteveBaker (talk) 16:28, 26 June 2013 (UTC)


 * Okay FindLaw seems to have this page FindLaw but perhaps there is a more comprehensive guide on auto repair laws which is what they seemed to be called, are there any mentions in consumer law? Also UDAP (Unfair and Deceptive Acts and Practices) Laws seem to have a lot to do with it possibly, but I still don't see which laws cover estimates or contracts for work. I wasn't given a copy, does that law take that into consideration? I haven't paid and said he wouldn't give me estimate until I did but I think this has more to do with estimate shopping, no?108.212.70.237 (talk) 21:20, 26 June 2013 (UTC)
 * As I explained earlier - we are absolutely not allowed to provide legal advice or to entertain discussion of your own findings. It is inappropriate for you to post such things here (even in response to your own question.  Please read Legal_disclaimer. SteveBaker (talk) 03:41, 27 June 2013 (UTC)

Frame shifting indel mutation confusion.
I've been reading this paper - http://genome.cshlp.org/content/23/5/749.full.pdf as an amateur but I'm confused by something.

It states on page 755:

"After accounting for these biases, we observed consistent depletion of indels across genic sequences relative to flanking intergenic regions, with coding sequence (CDS) displaying the strongest depletion of particularly frameshift indels (Fig. 3B). As a result, frame-preserving indels, and in particular indels of 3 bp in length, are the most abundant within CDS (Fig. 3C). Indel rates are also markedly reduced across a broad spectrum of functional noncoding sequences in the human genome (CNCs), and mild but significant reductions are seen in 59 UTRs and introns."

Which I take to mean that indels of length 3 are conserved while indels which cause a frame-shift are more subject to purifying selection within coding sequences (i.e. exons).

But on page 757 it states:

"As our set includes many indels within exons, we sought to examine their influence on gene expression and their relationship to complex trait associations. We first observed that frameshift-causing indels of lengths 1, 2, 4, and 5 were enriched with significant (FDR<0.5) exon-level gene expression associations compared to in-frame indels of length 3, a signal that itself is significant (Fisher’s exact test, P = 0.031) and is consistent with the action of nonsense-mediated decay (Fig. 4B). Further tests indicate that this signal is unlikely to be the product of length-driven differences in genotyping accuracy (see Methods)."

I'm not sure I understand what this means. Is it saying that genes with indels of length 3 are less expressed than genes with indels of lengths other than 3? Wouldn't nonsense-mediated decay act in the opposite direction, with frame-shifting indels casuing more premature stop codons? 87.194.131.188 (talk) 22:20, 26 June 2013 (UTC)


 * What they're saying in the second section is that 17.4% of the top associations with gene expression differences in the CEU cohort traced to indels. In other words, at the point of measuring sequence variations in a population and differences in RNA levels in that population - whether the higher one is frameshifted or not-frameshifted is not determined at that point.  And then they figure out that frameshifts 1,2,4,5 are enriched with gene expression associations, i.e. they make a difference, as expected from NMD.  It could be written more clearly - I don't see anything very obvious to prevent it from being interpreted backwards if you want - but the way it is written is at least consistent with the idea that the frameshifted genes have lower measured RNA levels due to NMD as expected. Wnt (talk) 06:59, 27 June 2013 (UTC)


 * Thank you. That clarifies is somewhat. 87.194.131.188 (talk) 16:44, 27 June 2013 (UTC)

Lobotomy
What would the process of having a lobotomy (fully conscious, assuming an analgesic is given to relieve pain but leave other awareness unimpaired) feel like? I understand there are obviously no primary sources for this procedure so could a conjecture be made based on the parts of the brain that are affected?

Thanks.

24.92.79.193 (talk) 23:19, 26 June 2013 (UTC)
 * We don't do conjecture here. You're free to read Lobotomy and arrive at your own conjectures, but it would be quite inappropriate for anyone here to give their own opinions or conjectures.  Of course, if reliable sources DO exist that answer your question, people should be free to link to those sources so you can read them.  -- Jayron  32  23:53, 26 June 2013 (UTC)


 * I'm not sure why there would "obviously" be no primary sources. I think the person was generally under total anaesthesia, but I'm not sure of it.  If you mean that such a person wouldn't be able to report his/her experiences, that's not true, or at least not always true.  A fascinating read is My Lobotomy, a first-person account of life before and after.  My impression of it was that it reflected a somewhat flat affect (if I'm using that term correctly), but did not seem to lack clarity about events per se. --Trovatore (talk) 10:05, 27 June 2013 (UTC)
 * I wonder whether the severed portions of the frontal lobes have a different experience of the matter? In the conscious case, I wonder whether the arteries of the region would experience pain akin to migraine - though admittedly, I have absolutely no comprehension of how such a crude procedure possibly avoided lethal bleeding in the brain!  I leave you with the song... Wnt (talk) 12:06, 27 June 2013 (UTC)


 * I seriously doubt that anybody would have tried that. Even disregarding the obvious ethical issues, without anesthesia or major sedation the chances of causing an epileptic seizure would be very high, and the last thing a surgeon wants is for the patient to start flailing uncontrollably during an operation.  As to what it would feel like, the best way to gain insight would be to read up on what a stroke feels like -- the answer is quite complex. Looie496 (talk) 15:23, 27 June 2013 (UTC)