Wikipedia:Reference desk/Archives/Science/2014 October 8

= October 8 =

Maths in physical geography, geology and environmental science courses at college
Are the above named courses quite mathematical at college level? At school level, a lot of these are qualitative but I'm guessing it becomes alot more quantitative at college level as most courses seem to. — Preceding unsigned comment added by 194.66.246.32 (talk) 11:34, 8 October 2014 (UTC)


 * Very much so. To the point of bordering on engineering in many cases. I studied environmental sciences and oceanography, and took exactly the same full sequence of math and physics classes as the civil engineering students. I would avoid any program that is not math and physics heavy, as that would mean you lack the serious tools to delve beneath the surface of the the subject matter. It would also greatly lower your salability on the job market, where the golden rule is "Math equals money" (and "Qualitative equals waiter". Better yet, go on for an outright engineering degree (petroleum or geology). I regret that I didn't. Dominus Vobisdu (talk) 13:53, 8 October 2014 (UTC)


 * It might also depend on the college's offerings and what program you're studying. E.g. at my university we had an option to take either calculus-based physics or non-calculus based physics. I'd also heard of life science courses with similar distinctions. El duderino (abides) 08:28, 10 October 2014 (UTC)

Unapproved drugs
In general, what is the legal status in the United States of pharmaceutical drugs that are not approved by the FDA? Assuming that the drug is not specifically listed as a scheduled drug of abuse (like List of Schedule I drugs (US), etc.), is it legal to buy, sell, and/or possess such substances? The reason I ask is that I came across this sentence, "Adrafinil does not currently have FDA approval and is thus unregulated in the United States" which I'm not sure is a correct. Specifically, does "is thus unregulated in the United States" automatically follow from "does not currently have FDA approval"? Clearly, an unapproved drug cannot be marketed for any specific medical use, but can it be bought or possessed "privately"? Are there other forms of regulation that cover FDA-unapproved drugs? 71.185.49.96 (talk) 14:10, 8 October 2014 (UTC)
 * Whoever wrote that might be jumping to a false conclusion. But the laws about drugs vary. Your best bet is to contact the FDA and ask about it. ←Baseball Bugs What's up, Doc? carrots→ 14:15, 8 October 2014 (UTC)
 * The Federal Analog Act means a drug doesn't have to be specifically listed if it's "substantially similar" to a listed drug. While I'm not sure that you're really thinking of drugs that the regulators/politicians think are abused, Designer drug does cover to some extent, how countries including some info on the US, are dealing with the fact it's becoming increasingly easy to manufacture new drugs with effects desired by those using them for recreational purposes. And also how those who wish to sell such drugs attempt to get around laws that try and stop them with varying degrees of success. (P.S. I hope people don't use this as an excuse to go offtopic into a lengthy discussion on the merits or lack thereof, of any attempts to control recreational drug usage. I didn't intend that by this comment, simply felt this stuff was specifically relevant as the OP seemed to believe a drug had to be specifically listed. And the stuff about how to handle the recent mass increase in new recreational drugs was something I'm aware of because of the debate and regulations here in NZ relating to "party pills". Nil Einne (talk) 15:08, 8 October 2014 (UTC)
 * Oh and a simple search for 'importing unapproved drug fda' finds these results which seem relevant to the original question  . From there a search for 'fda drug definition' as of course, saying it's illegal to import drugs is meaningless without the definition of a drug  . Nil Einne (talk) 15:15, 8 October 2014 (UTC)
 * So, based on my reading of the links you have provided ( thank you! ), it seems there is some regulation by the FDA regarding importation, interstate trade, and other commercial activities. But I don't see a clear answer to questions about personal use (for example, if someone buys a US-unapproved drug in another country where it is approved and then brings it home to take themself as a medication).  71.185.49.96 (talk) 17:44, 8 October 2014 (UTC)
 * The first 2 links of my second do mention the FDA stance on personal importation (the second one is simpler but seems to cover the basics). Whether this is supported by US law (i.e. including any interactions with the constitution), I can't say. While this obviously isn't legal advice, consider there are some reports of harmful side effects which require monitoring and there are alternatives to Adrafinil allegedly safer and allowed in the US, I'm not sure the FDA would agree to even personal importation if they consider it a drug. Nil Einne (talk) 20:07, 8 October 2014 (UTC)
 * P.S. Obviously not legal advice but I don't think adrafinil would be covered under the analog drug act. At least I can't find any sign of of any in schedule I or II that will covered it. Modafinil is in List of Schedule IV drugs (US) but the analog act doesn't cover that. Also in terms of US law, I couldn't find any particular court cases relating to the FDA's power to deal with personal importation. These cases mention here only seem to deal with larger scale importation. I am reminded of the iconic cases of Wickard v. Filburn and United States v. Lopez as well as cases like those dealing with personal usage of controlled drugs like marijuana Nil Einne (talk) 20:46, 8 October 2014 (UTC)

Cardiac cycle figure
I am writing a booklet for cardiology residents and fellows.I need permission to publish few of the figure (cardiac cycle and few others) from your website.I may make some modification in few of them.Reference of your website will be mentioned in of all of these diagrams with acknowledgment.I need an official permission for a transparent authorship. Warm regards Asadullah kundi Prof.(Rtd)Asadullah kundi, coordinator post graduate teaching National institute of cardiovascular diseases Karachi. — Preceding unsigned comment added by Asadkundi (talk • contribs) 17:58, 8 October 2014 (UTC)


 * I don't believe you need individual permission to use Wikipedia material. Just correctly attribute it to Wikipedia, and you're good to go.  Somebody else can probably point you to a policy page which states this explicitly. StuRat (talk) 18:26, 8 October 2014 (UTC)


 * (EC) You may want to ask at the WP:Help Desk if you have further queries but we have a page which should help Reusing Wikipedia content. Since the media you are using may be hosted in the Wikimedia Commons, it's probably helpful to read the other page linked there i.e. Commons:Commons:Reusing content outside Wikimedia. Note that while StuRat was trying to help, they've once again demonstrated the problem with randomly talking about stuff without citations (findable with 20 seconds). The linked page says all this and more and probably in a better way, but given the confusion that exists in this thread, I feel it important to clarify some key points to try and reduce confusion. Firstly, the English wikipedia allows content under the US fair use law under our WP:NFCC policy. Our usage is quite restrictive (in particular, there has to be no resonable chance of replacing the media) and I can't see why our cardiovascular health related articles would have such media, except perhaps for images of highly relevant deceased people or perhaps recordings related to groundbreaking research. Presuming when you say diagrams, you mean symbolic representations produced by drawings or computer program, not recordings of something in real life (photos, videos, sound), it seems very unlikely. But you should still check each media you wish to use, and in the unlikely event there is something used under NFCC, you'd need to either obtain permission from the copyright holder or consider whether Pakistani law allows it without permission (as we believe US law allows wikipedia). Also saying "correctly attribute it to Wikipedia" is confusing. Nearly all of our content which remains copyrighted (i.e. anything not in the public domain or otherwise without copyright), remains copyrighted by whoever produced it. We don't expect copyright assignment here. This means if there is any attribution requirement, the requirement is usually to the copyright holder/s not to wikipedia. A link to the wikimedia or wikipedia page may be enough to fill the attribution requirements but simply attributing it to wikipedia without a link will usually not be so, and the copyright holder may rightfully feel aggrieved if that's all you do. Note in particular that if the content was uploaded to the wikimedia commons, not everyone there likes wikipedia. So even more reason for the copyright holder to be annoyed if you attribute it to wikipedia. (Although because of the way commons works, there's may not much they can do about you linking to the wikipedia page rather than the commons one.) While the argument could be made a hyperlink is what's meant by "correctly attribute it to Wikipedia", I think many would not consider a hyperlink or more may be required based only upon the statement. In any case, attribution can be complicated. The wikimedia TOS (which apply to all projects) have required for a while that contributors accept a hyperlink for text but doesn't require this for media. The is the text seen in the edit window which says a hyperlink is enough, but it also says you release content under the CC and GFDL (which it's accepted isn't required for media) and the window isn't normally seen when uploading. And either way, this hasn't been there forever and we still accept media from elsewhere under a suitable licence. And the licences themselves don't necessarily specify that a hyperlink is enough (e.g. the CC says "credit reasonable to the medium or means"). So attribution requirements for media are frequently not that clear cut. And I think some allowed licences even let the contributor specify how to attribute. In some cases you also need to consider the risk of the content being deleted (even for text and if someone agreed to the current TOS, I'm not sure whether a hyperlink is enough when the content has been deleted). For this reason and considering media content often only has a few contributors, some reusers only attribute the contributor (their username on wikipedia or commons with a link to their userpage or what name they asked for) rather than bothering with wikipedia or commons And note simply attributing even if done properly may not be enough. Depending on the terms of the licence, you may need to mention the licence the media is under somewhere. In extreme cases like the GFDL or GPL, you'd even need to include the entire licence text. Note that ultimately the wikimedia TOS and the copyright holders licencing terms are what matter, not any policy. Of course if you find you can't meet the licence requirements, you're free to try and get individual permission from the copyright holder/s under terms which work for you. Finally, remember that while we take steps to weed out any content contributed without the copyright holder's permission (except as allowed under NFCC), we can't magically ensure all content is properly licenced so it's always possible some content you want to use is a copyright violation even here on wikipedia. And do understand that neither my comments, or anything on the pages I linked are intended as legal advice. Nil Einne (talk) 20:02, 8 October 2014 (UTC)


 * Here's the easiest way to use any image in a Wikipedia Article: 1) click the image to access the file page. 2) Check the licensing section relating to the image. 3) Abide by the information there.
 * For instance, today's PotD is available under the creative commons license, you are free to share and remix it as you please, as long as you attribute it to the author(Cyron Ray Macey, seen above the licensing box) properly - which includes providing a link (or the URL, for hardcopy) to the page where the image originated (on Flickr). Effovex (talk) 19:55, 8 October 2014 (UTC)


 * There's a lot of ideology on this stuff, with opinions ranging from extreme levels of attribution to, all too commonly, none at all. It rarely makes a real difference, and the proper answer is probably "whatever your boss believes in, right or wrong".  Many news sources I read simply attribute "Wikipedia", or when being extra accurate, "Wikimedia Commons".  (Usually figures are on Commons; the ones on Wikipedia might be used under "Fair Use" and not therefore free after all)  I can't tell you what to do; we're not supposed to be giving advice here of any kind, especially not legal advice. Wnt (talk) 14:48, 11 October 2014 (UTC)

Transparent Styrofoam ?
Is this possible ? It would be made of air-filled bubbles of clear plastic, all stuck together in sheets. The idea is to let light in but not let heat out, to provide a greenhouse effect. I realize you wouldn't be able to have a clear view through them, like with a glass window. However, it should be a superior thermal insulator to glass, and would be ideal for passive solar heating. (I suppose instead of air-filled, you could fill the bubbles with a gas that's a better thermal insulator, but I would guess this would be cost prohibitive.) StuRat (talk) 18:17, 8 October 2014 (UTC)


 * See aerogel. —Quondum 18:42, 8 October 2014 (UTC)


 * That seems to fit the bill, but looks like it's around $8 per square foot for the hyrophobic variety, which is needed to keep it from self destructing from humidity. That would seem to be prohibitive for insulating an entire greenhouse, but might work for just windows in a house. StuRat (talk) 19:50, 8 October 2014 (UTC)


 * That's a big jump from "Is it possible?" to "Is it cheap?" ;-) Yes, I think it has a way to go before it is affordable for large greenhouses.  That cost seems to in the same ballpark as standard glass panes. —Quondum 20:15, 8 October 2014 (UTC)


 * Aerogel is kinda fragile. The idea of having a kind of foam might be OK - but I doubt it would be very transparent.  The random orientation of the beads to the light would probably scatter it in all directions.  That said, I've seen transparent plastic sheets with corrugated interior structure - and also with hexagonal grid structure, and with box sections that run the length of the panel that ought to do something similar to what you're suggesting.   Indeed this greenhouse supplier seems to already be selling such things. SteveBaker (talk) 19:13, 8 October 2014 (UTC)


 * This is important: the "greenhouse effect" of the Earth's atmosphere is a bad name, because actual greenhouses do not work that way! See e.g. here . Unfortunately that page is sparse on refs, but it is written by a highly accomplished professor of meteorology (and he should know better, but I'll cut him some slack because he became emeritus 15 years ago). The basic idea of the greenhouse effect is well summarized by the article you linked, but actual greenhouses work by simply preventing convective flow, i.e. isolating a volume of air, while accepting insolation. That is, if a greenhouse's walls had all the same optical properties, but air moved freely through there, there would be only a tiny/negligible amount of heating over the ambient temperature. In contrast, the atmospheric greenhouse effect is solely about radiation fluxes, and has nothing to do with confinement. Unfortunately, we're stuck with the name for the atmospheric effect by now, but it's important to remember the actual mechanism retaining heat in a greenhouse is totally different.
 * So, if you want to replicate the effect of a greenhouse, as opposed to the "greenhouse effect" of the atmosphere, you just need any translucent material that will restrict the flow of air. Bubble wrap and soda bottles (e.g., , just google for more info) can also be used to make inexpensive backyard greenhouses. You can even find people building their own houses out of soda bottles via google, in part because of their insulating ability and low cost. Anyway, not sure what you're going for, but I'd stick to recycled and conventional materials (e.g. those linked by Steve above) for home-built greenhouses. SemanticMantis (talk) 20:26, 8 October 2014 (UTC)


 * I was thinking of it from a passive solar heating POV, say for a water tank to provide hot water for the house. Wrap some of that stuff around a tank, painted black, and it ought to heat up nicely in the sunlight.  The flexible version would be good here.


 * Another use would be to stuff in windows in winter, to let light in be not heat out. The rigid version would be better for that.StuRat (talk) 00:41, 9 October 2014 (UTC)


 * You can buy transparent corrugated plastic sheets. I've no idea if they are any better for greenhouses than glass or perspex, but I'd imagine that the thermal insulation is a lot better and the optical transparency is only slighly worse CS Miller (talk) 09:24, 9 October 2014 (UTC)


 * I have a south-facing conservatory with a sloping twin wall polycarbonate roof. It gets extremely hot in the summer and I have often thought I could pump water to the top of the flutes and, as it runs down to the bottom, it would collect heat, cooling the conservatory and providing warm water which could be fed through a coil to transfer the waste heat to a water tank. This water would then be further heated to provide domestic hot water. You would need to add antifreeze to stop it freezing in winter and you could add a reflective sheet underneath to improve the efficiency. You could also make cheap stand-alone solar collectors this way. As no-one seems to have come up with a system like this I wonder if there is a fundamental problem with the theory. Also bubble wrap, as mentioned above, is sold in the UK to line greenhouses in the winter months as a cheap insulation material. I can't see how transparent styrofoam would be any better, as in both cases the layer of material around the bubbles is extremely thin and would have a negligible effect on the insulation properties. Richerman    (talk) 13:29, 9 October 2014 (UTC)


 * I believe the more bubbles the better. The reason is radiation.  Heat radiates to get from one side of a bubble to the other, but once it arrives at the far side it might radiate back where it came from.  So, the more bubbles it has to cross the more opportunities for it to turn around.  With enough bubbles, it's something like a labyrinth, with the heat "getting lost" somewhere in the center.  It will eventually find it's way out, but that might take many hours or even days. StuRat (talk) 16:27, 11 October 2014 (UTC)

how do mobile phones know how much battery is left
do they measure current draw (voltage drop over some very small resistor, perhaps) and integrate, or is it a software thing plus some heuristic, or is there a concrete relationship between the battery's condition and its voltage output? my phone shows the state of the battery in percent. but it's not overly accurate (it's ok for everyday purposes, of course), sometimes the phone turns off when there are some percent left (according to itself), and sometimes the number even goes up even though the phone isn't charging... Asmrulz (talk) 19:54, 8 October 2014 (UTC)


 * It's probably a combination of things.


 * My phone (running a relatively recent version of Android) can tell me what percentage of battery power was consumed by which apps and sub-systems (eg the screen eats 47%, 13% was spend in "idle", 2% in voice calls, etc).  So I don't think it's directly measuring voltage to do that because the screen is on while I'm making calls - and it can't tell which of those things is causing the battery voltage to change.   So, more likely that it's gaining some estimate of number of CPU cycles, display-activity duration, GPS usage...and somehow integrating that over the time that applications are using those resources.


 * Measuring the battery voltage will tell you how much charge it has left for some technologies (disposable dry cells, for example) - but for others (like NiCd's), the voltage stays stable until right before they fail and the voltage drops suddenly over the last few minutes of battery life.  I'm not sure how the present generation of batteries change voltage over time - but I'd be surprised if the system used just that.


 * On the other hand, if it *just* used integration, it would become less and less correct over time. So I bet that it's measuring voltage when the charger is recharging it.
 * SteveBaker (talk) 20:29, 8 October 2014 (UTC)


 * For a detailed explanation, see:. — 71.20.250.51 (talk) 20:44, 8 October 2014 (UTC)
 * The app notes speak of "coulomb counting" which is not a term I'm familiar with, and it speaks of "charging at 0.2C" where C is some unspecified charging rate. An explanation of "coulomb counting" and a definition of rate "C" would be helpful. Edison (talk) 00:03, 9 October 2014 (UTC)
 * State of charge explains a bit. —  —explains a lot.  71.20.250.51 (talk) 02:29, 9 October 2014 (UTC)


 * See Battery charger for definition of "C" in this context. DMacks (talk) 02:39, 9 October 2014 (UTC)
 * Oh, I thought it might be like Douglas Adam's R. You know, where R17 is not any particular speed, but it is clearly far too fast. --Trovatore (talk) 05:24, 9 October 2014 (UTC)

Wrong structure in DiI
On the DiI page the molecular structure in the box top right seems to be incorrect. The long alkyl chains seem to have only 17 carbons each when they should have 18. My apologies but I'm too busy (lazy?) to get involved in actually trying to edit the page to fix the error. Can someone be notified of this who can do the actual work? Thanks. — Preceding unsigned comment added by 50.250.24.225 (talk) 19:58, 8 October 2014 (UTC)


 * Our article DiI redirects from 1, 1′-dioctadecyl-3,3,3′,3′-tetramethylindocarbocyanine perchlorate. The CAS number comes up dry  but PubChem  gives the name and structure, and is linked from the article.  Its structure does indeed show 18 carbons.  I do indeed confirm our image has 17 carbons.  Now, I have some considerable hesitations about saying that the 17 is "absolutely wrong" because our article mentions a series of dyes, and the simple abbreviation DiI might conceivably have been applied to two similar substances.  Taking one carbon off those chains shouldn't affect the color much.  But... I don't find any diheptadecyl compound in PubChem similar to it, so it would be at least more obscure; and ultimately the sources rule on Wikipedia, so yeah, it should be fixed with an extra line. Wnt (talk) 21:23, 8 October 2014 (UTC)
 * creator of disputed chemical-structure image. DMacks (talk) 02:45, 9 October 2014 (UTC)
 * Yes, it looks like the image I created is missing a carbon atom in each alkyl chain. I have now corrected it.  Thanks for catching the error and reporting it.  -- Ed (Edgar181) 11:06, 9 October 2014 (UTC)

General medical question.
''Please do NOT offer medical advice as I am NOT seeking medical advice. This question does NOT violate the reference desk guidelines. If you feel that it does, please at least take your concerns to the talk page when removing it to seek input from other editors. Do not act as judge, jury and executioner.' Thank you!'

Can bowel cancer and diverticulosis be detected on a CT scan?

If so, why do hospitals do colonoscopies instead?

Is a colonoscopy significantly better at detecting these diseases compared to a CT scan? — Preceding unsigned comment added by 181.48.214.242 (talk) 20:21, 8 October 2014 (UTC)


 * Looks like maybe, in some cases. Here's two articles on the topic . The first one says "Our results suggest that CT findings of fluid at the root of the mesentery and vascular engorgement are useful in distinguishing sigmoid diverticulitis from carcinoma of the sigmoid."
 * The second one says "The contrast enema should remain the initial and routine examination for the evaluation of patients with suspected diverticulitis. CT should be reserved for patients who are unable to have an adequate contrast enema, those with suspected distant or diffuse abdominal abscess, those who are unresponsive to medical therapy, and those who are candidates for percutaneous drainage."
 * But I'm just some guy on the internet who knows how to use google scholar. I suggest anyone that cares much about this read and understand the articles, as well as more recent literature. SemanticMantis (talk) 20:33, 8 October 2014 (UTC)


 * You're thinking virtual colonoscopy. Wnt (talk) 21:08, 8 October 2014 (UTC)


 * As they get better (higher resolution, less radiation) I would expect scans to replace many invasive tests. I'm not sure if we're there yet, though.  Personally I hope they get there soon, as many people would be willing to get a scan who don't want a camera rammed where the Sun don't shine. StuRat (talk) 00:29, 9 October 2014 (UTC)


 * Here is NCI's summary sheet on tests used to screen for bowel cancer, which is supposed to represent the expert consensus on the topic. You'll note that fecal occult blood tests, sigmoidscopy, and colonoscopy are considered standard screening tests for colorectal cancer, while virtual colonoscopy (and, contrast enema, that SemanticMantis refered to) are still regadred as experimental procedures. You can read more about the evidence underlying these determinations here. Abecedare (talk) 02:43, 9 October 2014 (UTC)

If this weren't funny it would be hilarious. They do give Cat scans fo diverticulosis. Only exploratory surgery gives a determinative result. I've had more than 2/3 of my colon removed--email me if you are in the NE US and want a referral. μηδείς (talk) 04:44, 9 October 2014 (UTC)