Wikipedia:Reference desk/Archives/Science/2017 April 10

= April 10 =

Transgender suicide rates
I'm looking for sources on transgender suicide rates. Benjamin (talk) 03:42, 10 April 2017 (UTC)


 * — Preceding unsigned comment added by Hofhof (talk • contribs) 11:17, 10 April 2017 (UTC)


 * Any high quality secondary sources? Benjamin (talk) 11:35, 11 April 2017 (UTC)

UV-vis spectroscopy
I've asked this once before, but nobody answered: In UV-vis spectroscopy, which wavelengths are the best for determination of aqueous Cu2+, Al3+/AlOH2+/Al(OH)2+, and PO43-/HPO42-/H2PO4-? 2601:646:8E01:7E0B:B50C:9D96:7F66:5859 (talk) 05:45, 10 April 2017 (UTC)
 * I think the UV-vis graph will show you which wavelengths are the best for determination of those aqueous chemicals. The graph will have wavelength at the X-axis and absorbance at the Y-axis. The peak of the curve means that the absorbance reaches a maximum at the corresponding wavelength. In my experience, UV-vis is done through software that is connected to the spectrophotometer machine, and the software will just output the information you want. You just have to set the range of wavelengths. 50.4.236.254 (talk) 12:51, 10 April 2017 (UTC)
 * I have an old, cheap machine which is not hooked up to any software -- you have to manually set the wavelength on the machine itself, and then it gives you a number for the absorbance. So where can I find the wavelengths I need? 2601:646:8E01:7E0B:E59B:261:F198:38A4 (talk) 00:45, 11 April 2017 (UTC)
 * In that case, you may have to test each chemical yourself. If you have the chemical samples, then you may put each sample in, one by one, and adjust for wavelength and check the absorbance reading for each wavelength. Then, you plot a curve. Do so for the other chemicals. 50.4.236.254 (talk) 01:18, 11 April 2017 (UTC)
 * For aqueous copper see https://carnicominstitute.org/wp/the-biggest-crime-of-all-time/?print=print Copper is easily detected in the visual range, with a peak absorption near 750nm and a maximum transmittance in the violet. But the wavelengths move with concentration. So you really need to plot a graph and look at the shape of the whole thing to match features. Your other ions are colourless, so you would have to check UV. Water also absorbs UV, so test some pure water too to see what you get. Our article is at Electromagnetic absorption by water. Water absorbs heavily shorter than 200nm. The metal ions would always be hydrated in water too so no Al3+ will be found in isolation in water, it would have about six molecules of water attached. Perhaps these will shift the absorption edge in the UV but I have not come up with any references for this. More normally IR or Raman spectroscopy would be used on the anions. Graeme Bartlett (talk) 02:15, 11 April 2017 (UTC)
 * Since water is a universal solvent, it can be used as a baseline for the other chemicals in aqueous solution. 50.4.236.254 (talk) 03:29, 11 April 2017 (UTC)

Downsides of fresh beef and natural preservatives/colors/flavors
I know many restaurants are trying to bring in customers by promoting "fresh beef" and "no artificial preservatives/colors/flavors". Though, this means that the food will have an increase in sodium intake, because sodium chloride, for centuries, has always been used as a natural preservative. Does this mean that the fresh beef will have higher content of sodium in order to preserve the beef? What kind of natural preservatives/colors/flavors are harmful in restaurant portion sizes? 50.4.236.254 (talk) 12:43, 10 April 2017 (UTC)
 * I'm a veggie, so this just ain't my party, but I don't recall restaurants pushing "fresh beef" as a good thing. If anything, high-end beef is sold on how old it is, and the premium product makes a point of it being "aged for 28 days" etc. Some meats (and fish!) are sold by freshness being a great virtue, but not beef.
 * No comment on salt levels. Andy Dingley (talk) 12:49, 10 April 2017 (UTC)
 * Interesting. Wendy's keeps promoting "fresh beef" in commercials, and McDonalds is trying to switch to fresh beef to stay competitive. I think that's a trend, because the fast food companies think that using fresh beef will attract more customers. By the way, is "veggie" some kind of vegetarian or a vegan? 50.4.236.254 (talk) 12:57, 10 April 2017 (UTC)
 * "is "veggie" some kind of vegetarian or a vegan?" Yes. It's a fairly common umbrella term. I happen to be vegetarian, so I eat eggs, dairy, but not fish.
 * I'm also British, if that makes a difference for which adverts I see. I don't think we have Wendys here, but McD's are busy advertising about the source of their beef, how local and how happy the cows are. In the UK animal welfare is a bigger current issue than simple quality. Although there was a recent McD campaign to try and counter the 'McD's is "all lips and arseholes"' viewpoint that does tend to circulate. Andy Dingley (talk) 13:15, 10 April 2017 (UTC)
 * I think many Westerners and Indians are lacto-ovo vegetarians. East Asian vegetarians are closer to ovo-vegetarianism (though eggs may be considered a luxury product, so veganism is the default), because of the lack of dairy farming and consumption. Soy milk production is very similar to cow's milk production, and tofu is like cheese. Cheese usually contains a lot of sodium content, while tofu can be flavored with salt or spices. A quick scan of a vegetarian menu in America hints that American vegetarians really like cheese. 50.4.236.254 (talk) 14:20, 10 April 2017 (UTC)
 * "Fresh" in the McD context, at the moment, is talking about fresh v. frozen. --jpgordon&#x1d122;&#x1d106; &#x1D110;&#x1d107; 13:17, 10 April 2017 (UTC)


 * Think some are falling to see the Sales & Marketing angle being used here. Like any good magician they use 'distraction' and misdirection to fool their audiences. 'Fresh' is the current word now. There is growing  concern,  that a few countries (like for instance the US) are using antibiotics as a growth promoter for their livestock  (especially beef) with a total disregarded for the problems that such usage may bring to the final consumer. We are already running out of effective antibiotics and intensive farming methods are making this crisis  far worse, by becoming  the breeding ground for more antibiotic resistant bacteria. So to stem this negative publicity, the S&M's  are promoting the word  'fresh',   'no artificial preservatives/colors/flavors', as if it also means natural,  wholesome and safe. --Aspro (talk) 15:50, 10 April 2017 (UTC)


 * I believe "fresh" is used as contrast to "frozen", not "aged". Some points:


 * 1) While meat frozen improperly can suffer from freezer burn, if handled properly this shouldn't be an issue.


 * 2) Never-frozen meat is rarely preserved by salting it. While it is possible to do so, the amount if salt required makes the food almost inedible.  You need to use small portions of it mixed with bland food, to make it palatable.  See salting (food).


 * 3) The salt added to restaurant foods is for flavor and to make you buy high-profit margin beverages.


 * 4) Never-frozen meat does have more of a risk of bacterial contamination, as it spends more time in the temperature danger zone (unless you butcher the animal at the restaurant). Proper cooking should reduce these risks. StuRat (talk) 17:19, 10 April 2017 (UTC)


 * The commercials specifically state "Fresh, never Frozen." They are using "Fresh" to mean "Not Frozen." It has nothing to do with how old the meat is. In the fine print, it usually states that frozen meat is used for Hawaii and Alaska as meat is usually frozen for long transits. To reinforce the meaning, the commercials show frozen hamburger patties and claim that they don't use those. 209.149.113.5 (talk) 19:18, 10 April 2017 (UTC)


 * The meat is put in a sterile container and then irradiated. Count Iblis (talk) 19:57, 10 April 2017 (UTC)


 * So that is a misdirection. Meat, rapidly frozen (before ice crystals can grow and puncture the cells etc.) is the same as freshly slaughtered meat. Frozen or unfrozen... meat can still contain  the hormones and anti-biotic  encouraged nasties that get pumped into cows. The US are making a song and dance about Europe (under the ]World Trade Organization) not allowing some of their meat products into Europe because of their  questionable consumer safety.  This is a big issue, because in some countries  like the US, if you or your child becomes ill, you simply go off to the doctor and pay what ever is necessary to get your child well again. - if you can afford it.  Even if it means paying for very expensive antibiotic more powerful than what  the cows were fed - from which the infection may have originated. In many parts of Europe we have better than Obama Health Care . If one is too sick to work, you are unable to pay any tax. Solution, provide cheap and affordable heath care to get you back to work again (and pay tax again). That means removing the cause of one's malady. Banning imported, questionable, American meat is one of them. As for irradiated food, we can buy food (for say mountaineering) that has  been gammer'd or betar'd but this  not permitted for everyday consumption.--Aspro (talk) 20:41, 10 April 2017 (UTC)


 * I suppose one can buy free-roaming, organic meat for personal health reasons. Though, those are more expensive than the conventionally grown ones derived from intensive animal farming. But you get what you pay for. If you eat cheap meat, then it has a cheap quality. If you eat organic meat derived from an animal that was raised well with plenty of space, then it is more valuable and healthier, because it is less disease-ridden. It may be more expensive, but the cost should be a reason to eat less meat or reserve meat on special holidays. 50.4.236.254 (talk) 22:59, 10 April 2017 (UTC)


 * Anyone for pink slime ? StuRat (talk) 02:11, 11 April 2017 (UTC)


 * Soylent Green may make a good alternative, for those that get turned off by pink stuff.--Aspro (talk) 20:58, 11 April 2017 (UTC)


 * ...or you can swirl them together to make rotten meat candy canes. StuRat (talk) 03:42, 14 April 2017 (UTC)


 * Once again, there's no intrinsic reason why organic meat is healthier. As for less intensively raised meat, again it's complicated. Less intensively raised meat may reduce bacterial levels but it also depends significantly on the practices and other factors. For example, eating intensively farmed chicken from KFC probably has a far lower risk of infectious diseases than you preparing the chicken yourself, no matter how fancy and non-intensively raised it is. (Eating at KFC may have other health risks, but the point is these don't relate to how the chickens are raised.) Note that while there may be a benefit in reducing the development and spread of some viral diseases, unless you're a farm worker your risk is likely almost negligible. There may be a benefit to the community (and your risk there is higher) but your personal form of meat consumption is basically irrelevant to that, what matters is what everyone else is doing. Even in terms of the use of antibiotics in farm animals, you need to consider the distinction between what your personal risks are, and the effect on the community. Of course, if you aren't selfish, you may want to consider these communal aspects (as well as a bunch of other things) in your decision, just as you may recycle for example, but this is different from suggesting it's going to make a difference to your health where it isn't. Nil Einne (talk) 10:09, 13 April 2017 (UTC)


 * A lot of the replacement of "artificial" for "natural" is just gibberish to fool the uninformed. A common replacement for nitrite-curing of meat, for instance, is curing the meat instead in beet- or carrot-juice, which chemically accomplishes the same thing, but causes the meat to taste awful. But the food is "healthy", so people are expecting it to taste bad. Someguy1221 (talk) 23:10, 10 April 2017 (UTC)


 * I found some reference to this here. But what perplexes me about meat curing is that nitrate and nitrite are treated as if they were the same thing.  I know nitrates are in beet juice and the soil; since they are so common I think of them as more natural, even if artificially produced.  I don't know if there's a natural precedent or longstanding use from the Middle Ages for nitrite, so I wonder more about it... Wnt (talk) 00:11, 12 April 2017 (UTC)


 * As for natural colors, the downsides are often less of a color range, and some of the ingredients are a bit gross, like the cochineal beetle parts in carmine (red). StuRat (talk) 04:33, 11 April 2017 (UTC)

Is 580°F twice as hot as 60°F? and other weird temperature math
I recognize that saying "120°F is twice as hot as 60°F" doesn't make sense, because the Celsius doubling equivalent of 60°F, ~15°C would get you 30°C, or 86°F.

I understand both Fahrenheit and Celsius have "arbitrary" zero points, and Kelvin uses an *absolute zero*, but converting to Kelvin, then back, doesn't seem right either as it yields bizarre sounding results, like that in the title.

Are there any other units of measurement that have this issue?

Is there a better way to consider the concept of "twice as hot"?

Thanks!

- MacAddct1984 (talk &#124; contribs) 13:25, 10 April 2017 (UTC)


 * For the kinetic theory of gases, which is as good a meaning of temperature as anything, then yes, 580 F is indeed twice as hot as 60 F.
 * I work with lasers, and have worked with plasmas. Where they have "negative" temperatures, on account of being so hot. They produce a condition (for the energy distributions of the atoms within them) of "population inversion". As the word "inversion" might suggest, this is in some, rather arcane, ways comparable to a temperature that would be negative. Andy Dingley (talk) 13:39, 10 April 2017 (UTC)


 * Heat content also needs to take into account the amount of material (usually mass or mole amounts) and its specific heat capacity rather than just raw temperature; for example a liter of water at some arbitrary temperature (say 25 degrees C) has a LOT more thermal energy than does a liter of air at the same temperature; and a liter of water has more thermal energy than does a milliliter of water. Concepts like enthalpy or internal energy are better for quantifying relationships.  Temperature really isn't a "countable" thing in the way that energy would be.  Saying something is twice the temperature is almost like saying red is twice the color as blue is... -- Jayron 32 13:44, 10 April 2017 (UTC)


 * You're right that converting to Kelvin is the only way that "twice as hot" is literally true, so if you mean anything else you should avoid using the phrase in any context where accuracy is important.
 * I don't have a cite, but I've noticed that rarely in some contexts "twice as hot" might use room temperature as a baseline. (If you have two overheating electronic components, the one that's 130F might be "twice as hot" as the one that's 100F because what you care about is the heat added by that component, but you don't see that usage often.)
 * In general, though, I've only commonly heard this expression used in casual conversation as a hyperbole where no actual measurements are implied. ("Texas weather is twice as hot as Maine weather!")


 * The other part of your question is easier to answer. There aren't too many units of measurements that have non-zero baselines like the common temperature units, but units that are nonlinear have a similar problem.  A sound that is "twice as loud" as a 1 decibel sound will not be 2 decibels. An earthquake that is "twice as strong" as a 1 on the richter scale will not be a 2 on the richter scale.  Etc.
 * 13:51, 10 April 2017 (UTC)
 * The decibel (dB) is not a unit of sound level, despite frequent misuse. It is 0.1 times the logarithm of a ratio. A sound Loudness must be expressed in units such as dB SPL (or for perception of single tones dBA) that define what is the 0 dB reference. "Twice as loud" is then by physical definition +3 dB (but the human ear limits the range that can be heard or tolerated.) Blooteuth (talk) 15:05, 10 April 2017 (UTC)
 * Sure, Decibel SPL. Fair enough. Point is, it's logarithmic, so it doesn't double or halve as one might otherwise expect. ApLundell (talk) 15:21, 10 April 2017 (UTC)
 * Which, of course, hints at other Decibel-based units that answer the question. The other one you might commonly see is dBm (decibel milliwatt) used to compare radio signal reception. (You're most likely to see this measuring wifi reception.) This is particularly resistant against easy doubling or halving because your wifi reception is almost certainly negative dBm even though obviously a positive amount of power is being detected.ApLundell (talk) 15:31, 10 April 2017 (UTC)
 * Digital-smart but analog-ignorant engineering has had tragicomic consequence. A company responsible for international emergency communication needed a survey of its radio coverage. A campaign of thousands of field strength measurements was initiated at considerable expense. The measuring instruments indicated values in dBμV (0 dBμV = -60dBmV = -120 dBV). In presenting a "tidy" report to management, someone "smoothed" the raw measurements by taking the arithmetic mean or Average of groups of values. After this, our hero saw no reason to preserve the raw measurements and the entire campaign cost was effectively wasted. Blooteuth (talk) 18:21, 10 April 2017 (UTC)
 * I would enjoy reading the details of such a spectacular screw-up. Do you have a cite? ApLundell (talk) 18:26, 10 April 2017 (UTC)
 * Suave mare magno..? I know of two instances of the screw-up but choose not to identify the engineers who have since learned from the experience. Industries where it can happen are a) broadcasting, especially by Geosynchronous satellite where footprint area represents a critical capital investment, and b) the Mobile phones used in Cellular networks display received signal strength indicator bars that are in steps of dB. The only way to calculate a correct average voltage (or power) is by converting values given in dBV (or dBm) to volts (or milliwatts) respectively before averaging them together.


 * The subject is sensitive to me because I was asked by a company management to invent a technical "justification" for the incorrect adding of decibels that had been programmed into survey equipment already delivered and in use.


 * Analog-savvy engineers do sometimes add together values in decibel units; this is a correct way of calculating the overall gain of a signal path through a chain of stages with individual gains (positive dB values i.e. amplifiers) and losses (negative dB values). Two-port network develops the theory in full to cover both forward and reverse interactions between stages. Blooteuth (talk) 14:16, 11 April 2017 (UTC)
 * Musical pitch is also a nonlinear scale. Each one-octave increment is "twice as high" in frequency (two octaves up is four times as high, three octaves is eight times as high). DMacks (talk) 15:40, 10 April 2017 (UTC)


 * (ec)Well, it may seem bizarre, but it's the only (?) definition that makes physical sense. In thermodynamics, temperature is (e.g.) a measure for the average kinetic energy of particles of an ideal gas. If you double the temperature measured in Kelvin, you double the kinetic energy of the particles. --Stephan Schulz (talk) 13:51, 10 April 2017 (UTC)


 * Any time people don't have a universal concept of the baseline, this situation can occur. If one plane is in level flight at a height of 1000 feet and another is directly above it at 2000 ft, one might say the second is "twice as high". But if they then continue flying straight forward over a 500-foot mountain, it's pretty confusing to say that the second is now "three times as high" as the first, but compared to the ground they are now only 500 ft and 1500 ft respectively. So instead one references sea level rather than ground level for altitude, but that means 2000 ft vs 1000 ft compared to the ground might be much greater than "twice as high" by visual appearance if the ground is high. DMacks (talk) 14:04, 10 April 2017 (UTC)
 * Relative to the centre of the Earth, all aircraft are at the same height to within a rounding error. Someguy1221 (talk) 23:13, 10 April 2017 (UTC)


 * For some background, see Level of measurement. -- zzuuzz (talk) 18:33, 10 April 2017 (UTC)
 * Just a note &mdash; the absolute-temperature equivalent of Fahrenheit is the Rankine scale. 60 degrees Fahrenheit equals 519.67 degrees Rankine.  Double that is 1039.34 degrees Rankine, which is 579.67 degrees Fahrenheit, the same you got from the Kelvin scale.  This is a pretty trivial observation, of course, but I wouldn't want anyone to think that the answer is specific to a particular unit.  It's what you get whenever you double the absolute temperature, regardless of the temperature scale you use to do that. --Trovatore (talk) 00:01, 11 April 2017 (UTC)
 * Just a note &mdash; the absolute-temperature equivalent of Fahrenheit is the Rankine scale. 60 degrees Fahrenheit equals 519.67 degrees Rankine.  Double that is 1039.34 degrees Rankine, which is 579.67 degrees Fahrenheit, the same you got from the Kelvin scale.  This is a pretty trivial observation, of course, but I wouldn't want anyone to think that the answer is specific to a particular unit.  It's what you get whenever you double the absolute temperature, regardless of the temperature scale you use to do that. --Trovatore (talk) 00:01, 11 April 2017 (UTC)