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September 14

Defibrillator units

I was watching an early episode of Law & Order (season 2, episode 5 "God Bless the Child") in which hospital staff use a defibrillator in an attempt to resuscitate a small child. The doctor holding the paddles instructs a nurse to set the device to "18 watts per second". Now I'm no brilliant physicist, but if I remember rightly, watts are already joules per second. That would make this unit joules per second per second which would be rate of change of power. I googled around and there are other sources that refer to watts per second as the unit for defibrillation such as this one (which seems to get the relationship between joules and watts wrt time backwards). Some other sources quote doses in watt seconds, which would make more sense, as that reduces to joules but the terminology makes it clear to the operator that the machine is delivering a power for a time period. Does anyone know how the units of defibrillators are normally used in a typical hospital setting? 114.124.175.125 (talk) 00:49, 14 September 2018 (UTC)[reply]

Here is a great review article from the American Heart Association: Defibrillation - 2010 International Consensus on Cardiopulmonary Resuscitation and Emergency Cardiovascular Care Science With Treatment Recommendations. It's part of a whole series of scientific review, published in the October 2010 issue of Circulation (Vol. 122, No. 16), in which a panel of experts detailed the scientific studies and made recommendations for clinical use.

In scientific literature, defibrillation is characterized using several parameters: among them are the paddle type and placement; the total energy; the waveform of the shock; the number of shocks; and the energy level per shock, measured in Joules.

In a clinical setting - like a hospital - scientific accuracy might be sacrificed during common use. If the machine is an AED - an Automated external defibrillator - the operator might have limited or zero medical and scientific training. Though in many places, use of an AED is restricted to only those emergency responders who have certain levels of professional qualification - in other places, the recommended procedure is for the first person near the victim - trained or otherwise - to use the machine. So you can see how the operator might mess up some of the details of the physics.

"Watts per second" is a nonsensical physical unit, at least in the context of measuring an electrical shock during a medical defibrillation procedure. Even if we're generous and we assume the fictional character misspoke, and meant to say "eighteen watts-times-seconds," that's equal to eighteen joules, and it's not a meaningful or reasonable quantity of energy for a defib. Defib shocks are normally in the range of 100 to 300 joules. The duration of time that this energy is delivered is very short - different machines use different waveforms, but all the energy is usually delivered in the first 15 or 20 milliseconds. Normally this would be characterized by describing the energy (in Joules) and the waveform (by naming it, out of a small set of common waveforms like "Pulsed Biphasic Waveform" or "Biphasic Truncated Exponential Waveform"). If the user were a physicist and felt like wasting time during the emergency, they might convert to using watts as the unit of measurement, and compute somewhere between 1 and 2 kilowatts during the application of the shock.

As always, the easy way out is to forgive a little poetic license in a work of fiction - they shouted some technobabble for dramatic effect, and the show's writers probably spent less time researching the topic than I did just now. But hey, in addition to being a volunteer science-enthusiast, I'm also a volunteer emergency-responder and I like to know a little bit of theory in case it ever saves a few seconds during an emergency.

You can sign up to learn more about AEDs; a great resource that's probably available in your community is the Red Cross AED training class - they'll probably encourage you to get a CPR refresher too. "The average response time for first responders once 911 is called is 8-12 minutes. For each minute defibrillation is delayed, the chance of survival reduces by approximately 10%." Or, as I like to phrase it: the professionals are, by definition, the second responders to your emergency: you are the first responder - so why not take some time to prepare for it now?

Nimur (talk) 05:00, 14 September 2018 (UTC)[reply]

Eighteen joules is certainly a reasonable quantity of energy for a pediatric defibrillation (as implied by the original question). Generally the "dose" is 2 J/kg for the first attempt, so 18 joules is right for a 9 kg (20 lb.) child. - Nunh-huh 19:12, 14 September 2018 (UTC)[reply]

I second what Nimur said about the value of getting even minimal training. AEDs are widely deployed in public places now and stupid-easy to use. Some are just "slap the pads on two places on the chest--there is a pictograph on the pads themselves and it doesn't matter which goes where; press the big button and then follow the instructions that the device's voice tells you" (things like "call 911; hands off; shock delivered" and a metronome for chest compressions). And hands-only CPR is pretty simple too (plus a great soundtrack!). Some key AHA data are that the survival rate for cardiac arrest that occurs outside of a hospital setting in communities where AEDs are available and people have AED/CPR training is nearly 40%, vs <10% overall. Part of the basis for improvement is that 23% of those patients initially have shockable rhythms. DMacks (talk) 15:16, 14 September 2018 (UTC)[reply]

I agree that it's useful to be trained in AEDs (even a bonehead like me can follow their instructions), but they're entirely a side issue to the question. The OP specified that the scene took place in a hospital, not at the scene of a first respondent attempting to use an AED. Matt Deres (talk) 17:05, 14 September 2018 (UTC)[reply]

Coming back to the original scenario (thanks Matt Deres for keeping us loosely on track!), doi:10.1001/jama.2010.1576 has the interesting conclusion that "Among hospitalized patients with cardiac arrest, use of AEDs was not associated with improved survival." It had no statistically significant effect on those with shockable rhythms (and these accounted for a lower percentage of patients than out-of-hospital case) and a detrimental effect on those without shockable rhythms. They propose that a major effect is that AED delays CPR and other emergency treatment actions. A systematic review study[1] reminds that although AEDs in hospitals are not effective, the basis for comparison is normal external defibrilation (which is presumably promptly available in that setting). I haven't yet found data for effectiveness of non-external. DMacks (talk) 22:38, 14 September 2018 (UTC)[reply]

Did Prohibition Reduce Drinking?

Our article on Repeal of Prohibition in the United States says that:

Alcohol consumption declined dramatically during Prohibition.
Violent crime did not increase dramatically during Prohibition.
Organized crime did not increase during prohibition.

There are indeed some sources that support at least some of those claims,[2][3] but a `quick web search also finds:

So which view is supported by the sources? Or could it be, as one source says, "In truth, nobody really knows exactly how much alcohol consumption increased or decreased during Prohibition. The reason was simple enough -- people like Al Capone didn't pay taxes on their product and thereby report their production to the government. Licensed saloons became illegal speakeasies, and many common citizens took advantage of the high sales price of illegal booze by secretly manufacturing booze in their own bathtubs."? --Guy Macon (talk) 04:43, 14 September 2018 (UTC)[reply]

And don't forget the yeast-flavored grape juice that would "go bad" if you added sugar and then waited. Anyway, regarding at least the first point, it is true that the certainty on this is pretty shit, and scholars bicker over the flaws in any method, but as far as I can tell, all the indirect evidence points to a singular conclusion: alcohol consumption declined a lot. Both contemporary and modern estimates of illegal alcohol production and consumption are vastly below the surrounding time periods, arrests for public drunkenness declined by two thirds, deaths from alcohol related illnesses declined by 80%... I'd say that there are arguments that the mainstream view is wrong, or poorly supported by the evidence, and it's certainly true that all available evidence is circumstantial, but it seems pretty damned uniform in where it points: [4]. Someguy1221 (talk) 06:16, 14 September 2018 (UTC)[reply]

Deaths from alcohol related illnesses declined by 80%?

"Deaths from Alcoholism. In New York City, from 1900 through 1909, there was an average of 526 deaths annually attributable to alcoholism.

From 1910 through 1917, the average number was 619.

It plummeted to 183 for the years 1918 through 1922.

Thereafter, the figure rose, averaging a new high of 639 for the years 1923 through 1927.

Total deaths from alcoholism in the United States show a comparable trend, with the gradual increase resuming somewhat earlier, about 1922."

"These statistics should be qualified by the observations of Dr. Charles Morris, Chief Medical Examiner for New York City: 'In making out death certificates (which are basic to Census Reports) private or family physicians commonly avoid entry of alcoholism as a cause of death whenever possible. This practice was more prevalent under the National Dry Law than it was in preprohibition time' ".[5] --Guy Macon (talk) 07:15, 14 September 2018 (UTC)[reply]

80% decline is the figure from Gebhart, J. C., Statistical studies of enforcement and social effects, 1930, which is based on contemporary nation-wide statistics, though I can't find an online version. Specifically 5 per 100,000 persons per year prior, dipping to a low of 1 per 100,000 during. Notably, Gebhart was actually anti-prohibition, and believed certain causes of death were under-reported (indeed, it is today a point of contention with this type of measure that at the time, there was no consistent nationwide reporting of causes of death, and standards varied over time in particular places). Someguy1221 (talk) 07:31, 14 September 2018 (UTC)[reply]

And yet The Effect of Alcohol Prohibition on Alcohol Consumption[6] by Jeffrey Miron [7] of the National Bureau of Economic Research says "The overall conclusion of this paper is that Prohibition exerted a modest and possibly even a positive effect on alcohol consumption". So alcohol deaths dropped by a whopping 80% while alcohol consumption stayed about the same? Is there something extra healthy about bathtub gin? Or did Gebhart's 1930 figures simply reflect that during prohibition physicians avoided listing alcohol as a cause of death? --Guy Macon (talk) 12:32, 14 September 2018 (UTC)[reply]

The Miron study is however based entirely on the correlation between the number of deaths due to cirrhosis and alcohol usage (something the author somehow fails to mention in the abstract), since there is simply no real data on alcohol supply or demand in that period. The study does acknowledge one weakness of this method: cirrhosis is correlated mainly with heavy alcohol usage, and so may not be greatly effected by a decrease in casual alcohol consumption. A more solid conclusion from the study then would be to say that the number of heavy drinkers probably did not decrease significantly during prohibition. That is not to say that the total amount of alcohol consumed stayed the same. Also note that this is a working paper, so it has not undergone peer review (yet). - Lindert (talk) 13:13, 14 September 2018 (UTC)[reply]

Using cirrhosis as an indicator of alcohol consumption is an interesting idea. According to our article on it, worldwide 57% of cirrhosis is attributable to hepatitis, and 20% to alcohol consumption. In the US the (current) number is 40% alcohol -- probably because we have better treatments for hepatitis. I wonder whether those percentages hold in the 1920s and 1930s, and whether the incidence of hepatitis remained steady during that period.

Another interesting factor; a bunch of light drinkers consuming X amount of alcohol would result in less cirrhosis than a smaller number of heavy drinkers consuming the same amount. It's heaviy drinking that ruins your liver. I don't have any figures, but it is plausible that light drinkers were more likely to become nondrinkers once it became illegal.

There is also a matter of timing. Increased alcohol consumption doesn't cause an immediate increase in deaths by cirrhosis. It take a while to destroy your liver. A decrease in deaths by cirrhosis follows a decrease in alcohol consumption much quicker; livers that aren't yet bad enough to kill you start healing if you stop drinking. The two are certainly cause/effect related, but it isn't a simple one-to-one correlation. --Guy Macon (talk) 17:54, 14 September 2018 (UTC)[reply]

Death from cirrhosis can also go under-reported (if there is no autopsy). Ruslik_Zero 20:23, 15 September 2018 (UTC)[reply]

I wonder if the autopsy rate was different in the 1920s compared to the 1930s. The more I look into this the less I like the absolute certainty that is in our article. --Guy Macon (talk) 04:04, 16 September 2018 (UTC)[reply]

All of the 3 assumptions on Developments are based on official statistics, which seem most unfit to estimate black markets and their circumstances. Therefor any such assumption should be mentioned as "based on very limited official knowledge" due to their systematically hidden nature. --Kharon (talk) 10:59, 16 September 2018 (UTC)[reply]

There is an interesting article about similar anti-alcohol campaign. Ruslik_Zero 20:19, 16 September 2018 (UTC)[reply]

Internation standard

Is anyone having knowledge of international quality standard that are to be followed for equipment racks and enclosures. 112.133.223.2 (talk) —Preceding undated comment added 06:24, 14 September 2018 (UTC)[reply]

Try here: 19-inch_rack#Specifications 196.213.35.147 (talk) 06:56, 14 September 2018 (UTC)[reply]

Best also search for ISO-Norms (International Organization for Standardization). --Kharon (talk) 10:41, 16 September 2018 (UTC)[reply]

Unidentified farm crop

Can anyone help me identify the crop in this picture? Taken on 9 June at 36°20′58″N 76°59′53″W / 36.34944°N 76.99806°W / 36.34944; -76.99806; there were a lot of fields in the area with the same crop, and I can't remember ever seeing such a crop anywhere else. Nyttend (talk) 14:00, 14 September 2018 (UTC)[reply]

Looks like clary sage to me. 216.59.42.36 (talk) 16:40, 14 September 2018 (UTC)[reply]

To me too: https://www.ncfieldfamily.org/farm/on-the-scent-of-sage/ 194.174.73.80 (talk) 16:57, 14 September 2018 (UTC) Marco Pagliero Berlin[reply]

Another option is lavender, though the plants tend to form more rounded shrubs that you see in the OP's picture. Matt Deres (talk) 17:11, 14 September 2018 (UTC)[reply]

Per the clary sage article, "In the United States, large scale production is concentrated in northeastern North Carolina in the counties surrounding Bertie County, NC." This is just the next county north of Bertie. Thanks! Nyttend (talk) 17:19, 14 September 2018 (UTC)[reply]

September 15

Is there something that is non-inflammable 100%?

As I understood everything is flammable (includes rocks and stones as we can see in lava) but all of the materials in the world are kind of located on the scale of flammability and while some require a very low temperature to be flamed and to change form, other materials require a very high temperature (like stones) to be flamed and change form. Is it correct? or there are exception for totally non-inflammable materials? 93.126.116.89 (talk) 05:08, 15 September 2018 (UTC)[reply]

Combustion products are essentially non-flammable, such as carbon dioxide, water, etc. but I suppose in principle even those substances can be reacted to higher and higher oxidation states. 139.194.65.208 (talk) 05:14, 15 September 2018 (UTC)[reply]

By the way...flammable and inflammable have the same meaning. Non-flammable is the term for something that doesn't burn. 139.194.65.208 (talk) 05:16, 15 September 2018 (UTC)[reply]

Thank you, I really didn't know it. I corrected it. 93.126.116.89 (talk) 14:53, 15 September 2018 (UTC)[reply]

In principle, CO₂ and H₂O really are completely combusted, with C and H in their maximum possible oxidation states and O happy with a full shell. Trying to oxidise these further would either be completely impossible (H doesn't have any more electrons for anything else to take) or require more energy than any chemical reaction could give (trying to involve the 1s electrons of carbon). Double sharp (talk) 06:15, 15 September 2018 (UTC) (Answer struck based on Ruslik0's comment, raising something which I somehow completely forgot about: this answer is only accurate if we restrict ourselves to combustion in air.) Double sharp (talk) 03:38, 16 September 2018 (UTC)[reply]

I get what you are saying but H2O2 Greglocock (talk) 06:34, 15 September 2018 (UTC)[reply]

H₂O₂ is thermodynamically unstable and slowly disproportionates to water and oxygen, so it doesn't affect the statement. ^_^ Double sharp (talk) 08:07, 15 September 2018 (UTC)[reply]

Of course the H is in the same oxidation state in both water and peroxide, but the oxygen is in the -2 state in water but increases to the -1 state in peroxide. It is further increased to -1/2 in superoxides. 139.194.67.236 (talk) 13:00, 15 September 2018 (UTC)[reply]

Yes, but we're typically thinking of oxidising the other element in an oxide, not oxygen itself. Otherwise, we could further oxidise oxygen in all oxides just by decomposing them to their constituent elements. Double sharp (talk) 15:17, 15 September 2018 (UTC)[reply]

Water can burn quite well in atmosphere of fluorine. Ruslik_Zero 20:05, 15 September 2018 (UTC)[reply]

Hmm, good point. I guess I must have been thinking implicitly of combustion in air. I've struck my original answer and added a note explaining that it only applies to that case. Double sharp (talk) 03:38, 16 September 2018 (UTC)[reply]

@Double sharp: What you say is true, in any sane way, yet ... well, in principle, I could take any substance and convert it into a plasma. Then I could take oxygen and convert it to plasma. Then I could mix the two plasmas and they would be intermingled, no matter what, with some conceptual release of energy no matter what, because entropy. Therefore ... everything is combustible at a high enough temperature. ??? Wnt (talk) 21:51, 15 September 2018 (UTC)[reply]

Naturally, we have an article on this - Combustibility and flammability. It appears to confine the definition of flammable to the commonly understood concept of something burning in the presence of oxygen. It lists some non-flammable materials. Interstingly, they include Diesel fuel. Haven't read it all so as to get my head around that yet. HiLo48 (talk) 06:27, 15 September 2018 (UTC)[reply]

The article seems to indicate that diesel fuel is considered combustible but not flammable, because it must be heated above room temperature before it ignites. Double sharp (talk) 08:09, 15 September 2018 (UTC)[reply]

Just to point out that lava isn't burning, it's molten. Some rocks can be burnt, such as limestone when making quicklime. Although that's strictly thermal decomposition, rather than burning. Mikenorton (talk) 08:54, 15 September 2018 (UTC)[reply]

Interesting, but I'd like to know based on what do you say that lava isn't burning while we can see it red and everything that you put into it burn as well.93.126.116.89 (talk) 15:02, 15 September 2018 (UTC)[reply]

Melting and burning are not the same thing. ←Baseball Bugs ^{What's up, Doc?} carrots→ 16:34, 15 September 2018 (UTC)[reply]

The red/orange glow of lava is black-body radiation. The rock is so hot that it glows in the visible spectrum. This doesn't have anything to do with combustion. --47.146.63.87 (talk) 04:09, 16 September 2018 (UTC)[reply]

One obvious example of a rock that burns is coal. 139.194.67.236 (talk) 12:51, 15 September 2018 (UTC)[reply]

Coal and jet are rocks that can be set on fire, sometimes with interesting results. --Guy Macon (talk) 13:01, 15 September 2018 (UTC)[reply]

Can I conclude from the article that mentioned above above that liquids are the only non-inflammable substance, or there're are also solid materials that no mater what they'll not be burnt? Basically except for water I didn't find a specific solid material that is non-flammable. 93.126.116.89 (talk) 15:00, 15 September 2018 (UTC)[reply]

Any oxide is non-flammable. I can think of glass or quartz (SiO2) or corundum (Al2O3). Ruslik_Zero 20:03, 15 September 2018 (UTC)[reply]

Tin(II) oxide has a bone to pick with you. That's just one example - conventional burning is still possible for an oxidized material if it can still be oxidized even further by oxygen. Someguy1221 (talk) 03:56, 16 September 2018 (UTC)[reply]

Of course, carbon monoxide can also be burned, and is in fact the gas that is combusted in many pyrometallurgical processes. 139.194.67.236 (talk) 10:16, 16 September 2018 (UTC)[reply]

In the presence of pure oxygen a lot of unlikely substances can undergo combustion - steel cutting torches depend on this to convert steel to rust, thereby cutting it. Per mention above, there is a difference between temperature-induced incandescence (i.e., fresh lava) and actual combustion. The flames seen coming from lava are from the decomposition of organic material that the lava has covered, which combust. Acroterion (talk) 17:17, 15 September 2018 (UTC)[reply]

Funny, non of all the experts, who tried to answer here till now, who obviously have some remarkable deep insight into chemistry and/or physics, mentioned noble gases which are not only 100% "non-inflammable" but even widely used in the industry as Shielding gas (usually Argon) to even prevent any "burning" (aka Exothermic reaction based on Oxygen) from happening. --Kharon (talk) 10:32, 16 September 2018 (UTC)[reply]

Except numerous oxides of noble gasses exist such as XeO4. 139.194.67.236 (talk) 13:39, 16 September 2018 (UTC)[reply]

XeO4 is manufactured by Synthesis. That hardly counts as inflammable. Whats the other "numerous oxides of noble gasses" that exist according to you? I bet they are all synthetic. With your argumentative pattern you could as well claim that Bricks fly, since you could form them like a wing and add enough air flow to actually make them fly. --Kharon (talk) 14:01, 16 September 2018 (UTC)[reply]

Our Noble gas compound article is a good place to start learning about the various classes of compounds of them that exist. For your specific concern about "synthesis", I assume you mean other than simply combining, say, xenon and oxygen at some temperature and pressure and getting xenon oxide? See doi:10.1038/nchem.2528 for examples of exactly that. Given the difficulty in getting it to happen, I suppose it's "combustible" not "flammable", and given the scale on which the reaction is performed, there is presumably not an actual "flame". DMacks (talk) 14:13, 16 September 2018 (UTC)[reply]

@DMacks. "Some temperature"? I was actually most impressed that XeO4 explodes above −35.9 °C and started wondering how many hundred Million $ a laboratory probably would cost that would be able to do both, the synthesis and storage, like some casual task for the day.

Btw, have you actually read your source yourself. At least until it mentions "Diamond-anvil-cell experiments" in the second sentence of its description? --Kharon (talk) 21:47, 16 September 2018 (UTC)[reply]

Diamond anvil cell experiments are relatively cheap (well, the pair of diamonds are a problem) because they're small scale. This makes them cheap to perform, also safe to perform. The reaction quantities are so small that even energetic results are still manageable. Andy Dingley (talk) 22:09, 16 September 2018 (UTC)[reply]

Of course I read the article before writing about it. That's why I clearly stated that the scale was small and the conditions were non-ambient. Even the diamonds of diamond anvils are only a few $K if I recall. And long-term storage of materials only a few tens of °C below zero is trivial too. Dry ice is not expensice even for small amounts to the general public, and large amounts or LN2 or low-temp freezers are present in every even poorly-equipped lab facility I've seen. DMacks (talk) 01:49, 17 September 2018 (UTC)[reply]

Indeed, at least the lighter noble gases should really be completely non-inflammable. Helium and neon should qualify under any sane definition since they have no known chemistry; argon should also count, because inserting Ar into an HF molecule isn't oxidising anything. Krypton will react with fluorine, which may count as combustion by some definitions. Double sharp (talk) 01:59, 17 September 2018 (UTC)[reply]

September 16

Heating of solids

It's known that a temperature increase increases the speed of molecules/atoms. Since in solids molecules are tightly packed and tied by intermolecular forces of attraction, having little or no room to move, this means that they should experience very negligible to no temperature increase at all. So why do solids have different thermal conductivity and in general it's relatively easy to heat up a solid material? 212.180.235.46 (talk) 12:06, 16 September 2018 (UTC)[reply]

Actually solid water (Ice) is less dense than fluid water and altho that is rather unique that is enough to prevent setting a general rule of matter "packings". Also atoms and their state have almost no significance for thermal conductivity. The real significance lies in the molecular "static", aka their arrangement in 2 or 3 dimensions as crystal, net or string. The most thermal conductiv natural material for example is Diamond with 1000 watts per metre-kelvin (W·m−1·K−1) and the (known) most conductive artificial materials are Carbon nanotubes (3500 W·m−1·K−1) and (molecular 2-dimensional) Graphene (5300 W⋅m−1⋅K−1). So you see that thermal conductivity is much more complicated than just how atoms swing (aka move) more or less dependent on their temperature.

The third part of your question is dependent on the Volumetric heat capacity AND thermal conductivity, which again does not follow a simple rule and contrary is a very individual perk of materials in general. --Kharon (talk) 12:57, 16 September 2018 (UTC)[reply]

It's known that a temperature increase increases the speed of molecules/atoms.

That's true as a statement, but it's not useful as a model unless you start to consider the laws which relate these two things. In a gas, kinetic theory does claim, "a temperature rise increases the speed", but it does so by showing the temperature to be proportional to the energy of each molecule, not its speed (i.e. the square of its speed, from the usual relation for kinetic energy).

It's similar in a solid. Temperature is proportional to the energy, not the speed. You might find phonons worth reading. The usual simple approximations begin by modelling the crystal lattice forces as atoms on springs, with a mathematical treatment as simple harmonic oscillators. This still works fine for a crystal or metal with a rigid lattice, but keep thinking about the energy for each atom (much of which is going into displacing that spring), not just their velocity, as if they were a free particle in a gas. Andy Dingley (talk) 13:20, 16 September 2018 (UTC)[reply]

Metal identity

Can the likely identity of the metal in these terminal blocks be inferred from the colour variations of the metal? 185.230.100.66 (talk) 15:58, 16 September 2018 (UTC)[reply]

No. Those are screws you're looking at, not the blocks, and their colour is due to a coating on them, not the underlying metal.

The blocks inside are usually brass, but modern ones are becoming ever more cheaply made and might become steel at some point. They're usually tinned or plated to make their surface more corrosion-resistant and avoid poor contact problems. You can tell brass from steel easily with a magnet. It's quite likely that there are steel screws in a brass block.

These 'chocolate block' connectors are also becoming less widely used, in favour of connectors (such as the Wago range) with sprung connectors. They have a perennial reputation for poor contacts over time. Andy Dingley (talk) 16:57, 16 September 2018 (UTC)[reply]

This is the correct link to the Wago range of connectors. 194.174.73.80 (talk) 10:53, 17 September 2018 (UTC) Marco Pagliero Berlin[reply]

The surface appears to be Cadmium but terminal screws are almost never pure cadmium but rather cadmium plated. A magnet will tell you if there is steel underneath.

https://www.google.com/search?q=Cadmium+plating&num=100&tbm=isch will show you what cadmium plating looks like. --Guy Macon (talk) 17:55, 16 September 2018 (UTC)[reply]

It won't be cadmium. Cadmium is so toxic that even the Chinese have stopped plating things with it. Now it looks like cadmium, but so do many other modern plating and conversion coating processes. You can even get "super cadmium-looking" processes, for the car restoration crowd. Andy Dingley (talk) 18:12, 16 September 2018 (UTC)[reply]

Metallurgy is a very specialized Science and Metallurgists have a masters degree. They are also the highest paid specialists in material science, i learned by chance a long time ago. So you may have to pay the 500$ bill for the correct professional answer to your Question! Sorry, way above my pay grade. --Kharon (talk) 22:17, 16 September 2018 (UTC)[reply]

Then why do you keep answering questions here, if you have nothing to contribute? Andy Dingley (talk) 23:44, 16 September 2018 (UTC)[reply]

Makes sense to me. It keeps people from too easily believing answers posted by other people who are guessing. --76.69.47.228 (talk) 01:54, 17 September 2018 (UTC)[reply]

I'm a metallurgist and I don't have a masters degree. Neither do any of my colleagues. I'm reasonably well paid, but I'm not the highest paid person around either. 139.194.65.208 (talk) 22:19, 17 September 2018 (UTC)[reply]

Obesity

Is it genetic or determined by what you eat?86.8.203.189 (talk) 18:31, 16 September 2018 (UTC)[reply]

Have you considered that both factors may be in play, and that there may be others as well, for example gut flora? Matters of biology are rarely simple. {The poster formerly known as 87.81.230.195} 90.208.172.36 (talk) 18:54, 16 September 2018 (UTC)[reply]

It can't be only genetics because anyone can starve to death and 3 pounds of butter has 12,250 calories. Sagittarian Milky Way (talk) 18:56, 16 September 2018 (UTC)[reply]

The answer is "Yes". ←Baseball Bugs ^{What's up, Doc?} carrots→ 19:07, 16 September 2018 (UTC)[reply]

Some people cannot get fat no matter how much they eat. 86.133.58.126 (talk) 19:12, 16 September 2018 (UTC)[reply]

Jack Sprat, for example. ←Baseball Bugs ^{What's up, Doc?} carrots→ 19:15, 16 September 2018 (UTC)[reply]

The nursery rhyme merely states that Jack couldn't eat fat, not that he couldn't get fat. It is certainly possible to get fat on a low-fat diet: the body is quite good at converting carbohydrates to fats. Wymspen (talk) 10:09, 19 September 2018 (UTC)[reply]

See Obesity#Causes. PrimeHunter (talk) 23:02, 16 September 2018 (UTC)[reply]

The more fat, refined grains and sugar you eat the less calories you can eat before you'll put on weight. This is because unlike whole grains, these food sources are empty calories that don't contain the nutrients the body needs for metabolism. The human body is a self-maintaining factory that cannot run on just fuel, it uses hundreds of thousands of different types of enzymes that need to be produced from the nutrients we eat. Count Iblis (talk) 16:24, 19 September 2018 (UTC)[reply]

Is the negative charge - the absence of the positive charge?

We used to say, based on the science - if I'm not mistaken, that the darkness is the absence of the light, because there're no photons at the medium of the darkness. True? So my question is about physics or chemical physics, is the negative charge is the absence of the positive charge? If it is, what is the explanation for that? (for example about light we say that there're are no photons but here in negative charge what is the actual absence in the micro-level?19:52, 16 September 2018 (UTC) — Preceding unsigned comment added by 93.126.116.89 (talk)

no, no, no. The attractive force is proportional to the negative charge times the positive charge, which can't be if the negative is just a lack of positive. Wnt (talk) 21:20, 16 September 2018 (UTC)[reply]

'Absence of charge' generally implies no charge. Only in some cases (where a negative charge carrier is expected) would it really be seen as implying a positive charge.

Charge is different to light (or mass). There are two forms of it, so there's a difference between 'negative' and 'absent' which doesn't arise for light.

The most common charge carrier (at least in discussion and description) is the negative electron (as electrons can travel freely in metals). But the 'natural' state of an atom is to be neutral (the number of positive and negative charges are equal). If a charge is removed, then yes, that's equivalent to gaining the opposing charge. So atoms in ionic bonding (how many molecules are formed) may easily lose or gain an electron (or two) to an adjoining atom; one becomes positively charged (an ion), one negatively charged. It's the electrons which move between atoms, not their protons, as the electrons are both less tightly bound and also lighter.

In semiconductors, both positive and negative charges are important. The idea of 'holes' is an importat one. It's just as important to account for a removed electron as it is for an excess electron. But this is the removal of an electron which was there, not merely the absence of one. Andy Dingley (talk) 21:55, 16 September 2018 (UTC)[reply]

Good answer. Excellent article. DroneB (talk) 16:03, 17 September 2018 (UTC)[reply]

Donated blood not clotting

Why does donated blood not clot? I thought, no air=no clot, but blood can clot inside our veins. Mix up some anti-coagulant into it? But, then wouldn't that be pretty inconvenient for recipients like accident victims and hemophiliacs? — Preceding unsigned comment added by 31.177.99.255 (talk) 22:14, 16 September 2018 (UTC)[reply]

I googled "why doesn't donated blood clot", and here's an answer:[8] ←Baseball Bugs ^{What's up, Doc?} carrots→ 22:46, 16 September 2018 (UTC)[reply]

Yes, I saw that page too, when I googled it. It does not touch the topics of my sub-questions. --31.177.99.255 (talk) 22:54, 16 September 2018 (UTC)[reply]

Just enough citrate is added to the blood in order to chelate most of the calcium. Calcium (specifically Ca²⁺) is required for coagulation (factor 4 in the coagulation cascade), so without free Ca²⁺ the blood will not clot in the bag. When blood is then transfused, because there is little unbound citrate in the bag, there will be little effect on the plasma calcium concentration, and hence coagulation in the body is possible as normal. The kidneys can then effectively clear the citrate from the body, although in the interim it may have other biological effects. Klbrain (talk) 00:34, 17 September 2018 (UTC)[reply]

A reference for the actual amounts of citrate vs calcium in a donated unit would be important here. How much of the calcium is actually bound and how much free citrate remains? The plasma calcium concentration is also affected by dilution of the added no-free-calcium blood in the recipient. A donated unit is about 0.5 L and a person has about 5 L total volume, so if we are talking about someone suffering from blood loss, mixing one unit of whole blood with no Ca++ into "well less than 5 L" of whole blood is easily a 10% drop. If one really needs blood, it's obviously an acute situation and side effects or interactions with other conditions can be addressed later. Headed slightly off the OP's question, the citrate is also a potential problem for the donor in apheresis, where the blood is withdrawn, citrate added, certain components of interest removed, and the rest returned to the donor. That means dumping a bunch of calcium-depleted blood and possibly excess citrate into the donor for a several-hour period. pmid:26607494 is an interesting read. DMacks (talk) 03:13, 17 September 2018 (UTC)[reply]

Not a direct answer, but the citations in the "trauma" section of this review [9] presumably mention it at some point? That talks about standard practices in the management of bleeding during surgery. In brief, if someone comes in needing a massive blood transfusion after an accident, coagulation is very carefully monitored and a variety of infusions are available to keep the blood behaving normally. Someguy1221 (talk) 03:25, 17 September 2018 (UTC)[reply]

The American Red Cross notes[10] that there actually can be a possibly clinically significant amount of anticoagulant infused, although it is indeed metabolized promptly assuming normal liver function and circulation. And it concurs with my thought that that the transient drop in free Ca++ can be an acute problem. And it notes that the transient presence of citric acid and then the presence of its metabolic products can also be an acute problem (blood pH and Ca++-level effects) for those who have certain circulatory or metabolic problems. DMacks (talk) 03:29, 17 September 2018 (UTC)[reply]

For educational value: blood does not clot inside our veins, except when something's wrong, and if it does it can cause serious problems and needs treatment. Blood is only "supposed" to clot when it leaves the blood vessels, which only occurs when trauma damages them. --47.146.63.87 (talk) 08:23, 21 September 2018 (UTC)[reply]

September 17

Oil and fat yields

Out of avocado oil, beeffat, butter, canola/rapeseed oil, castor oil, chickenfat, cocoa butter, coconut oil, corn oil, cottonseed oil, flaxseed oil, grapeseed oil, lard, olive oil, oliveseed oil, palm oil, palm kernal oil, peanut oil, pumpkin seed oil, rice bran oil, safflower oil, sesame oil, soybean oil, sunflower oil and tallow which need the most and least grams of source organism per gram? (mass right before harvest or slaughter) If you consider the livestock ate like 10 times it's weight in it's life and milk is only ~3% butter is the lowest yielding one an animal fat? (of course a low yielding plant is probably not "economically inefficient", just able to make oil and other valuable products at the same time (i.e. wine and cotton cloth)) Sagittarian Milky Way (talk) 15:18, 17 September 2018 (UTC)[reply]

Does it make sense to measure yield of products with greatly differing molecular weights in terms of grams of source material and grams of product? I'd think moles might be a better measure for the yield efficiency. See atom economy. --OuroborosCobra (talk) 21:42, 17 September 2018 (UTC)[reply]

Flu infection

I was reading our article on the flu and there's a passage that I'm having trouble understanding. It's the second paragraph from here, which says: "Influenza viruses bind through hemagglutinin onto sialic acid sugars on the surfaces of epithelial cells, typically in the nose, throat, and lungs of mammals, and intestines of birds (Stage 1 in infection figure). After the hemagglutinin is cleaved by a protease, the cell imports the virus by endocytosis." (there's are references, but it's offline - and likely beyond my understanding anyway!).

It's the last sentence. Okay, so hemagglutinin exists on the outer shell of the virus particle. This attaches to the sialic acid sugars on the surface of some cells. So far, so good. But where I'm stuck is how the cleaving of the hemagglutinin helps the virus gain entry. Does it act kind of like a key, "unlocking" sialic acid sugars (and therefore the surface of the cell)? If so, how does cleaving (i.e. breaking) the key help the virus? Proteolysis was linked in there, but it's not helping me picture the activity going on. Matt Deres (talk) 16:32, 17 September 2018 (UTC)[reply]

The source cited doesn't say that cleavage is necessary for endocytosis, it's just that the cleavage itself can only be carried out by specific extracellular proteins in mammalian flus and non-pathogenic avian flus. (In highly pathogenic avian flus, it happens inside the cell, and the enzymes involved are ubiquitous.) The actual deal with the cleavage, though, is that the HA protein has a short little loop on its side connecting the HA1 and HA2 subunits. When the loop is snipped, one of the loose ends becomes the fusion peptide described at Hemagglutinin (influenza)#Function of HA in Viral Entry, and the protein's structure also becomes capable of the pH-driven rearrangements necessary for membrane fusion (described at the same link). -165.234.252.11 (talk) 20:38, 17 September 2018 (UTC)[reply]

Ah! Thank you - excellent explanation! Matt Deres (talk) 01:52, 19 September 2018 (UTC)[reply]

Dog flappy leggy bit

Hey guys, I tried Googling to little avail, but I was wondering what that flappy bit connecting a dog's back leg to his body is called. Thanks in advance! Drewmutt (^ᴥ^) talk 18:06, 17 September 2018 (UTC)[reply]

Floof leg? CHRISSYMAD ❯❯❯¯\_(ツ)_/¯ 18:29, 17 September 2018 (UTC)[reply]

I'm seeing "fold of flank". Heaviside glow (talk) 18:36, 17 September 2018 (UTC)[reply]

Heaviside glow Floof fold? Floof flank? CHRISSYMAD ❯❯❯¯\_(ツ)_/¯ 18:54, 17 September 2018 (UTC)[reply]

Aerodynamic aid? Sagittarian Milky Way (talk) 22:10, 17 September 2018 (UTC)[reply]

"Fold of flank" (FOF) is described here:[11]. 107.15.157.44 (talk) 22:13, 17 September 2018 (UTC)[reply]

Works for me! Thanks Heaviside glow! Drewmutt (^ᴥ^) talk 17:40, 19 September 2018 (UTC)[reply]

September 18

Which charge is stronger, negative or positive?

Which of the charges (in chemistry, physics, electricity) is stronger, positive or negative? For example, if we have more negative than positive charge, the one that will be dominant is the negative or the positive charge cancels any negative charge? (I have the same question about having more positive than negative) 93.126.116.89 (talk) 05:19, 18 September 2018 (UTC)[reply]

Neither. They're equal and opposite. Did something give you the impression that one was stronger? --47.146.63.87 (talk) 05:36, 18 September 2018 (UTC)[reply]

To be more precise, a proton and electron have equal and opposite charges. However, it is possible for something to have more of one than another. For example, a hydrogen atom has one proton and one electron, giving it zero charge. If it loses its electron, it becomes a hydrogen ion with a +1 charge. A Chlorine atom can gain an extra electron, forming an ion with a -1 charge, while an oxygen atom can gain two extra electrons, giving it a -2 charge. (Chemical compounds form by combining positive and negative ions so that the charges balance out. That's why hydrogen chloride (HCL) has equal amounts of hydrogen and chlorine, but water (H2O) has twice as much hydrogen as oxygen). Iapetus (talk) 09:39, 18 September 2018 (UTC)[reply]

For a more complex answer at a fundamental level, see C-symmetry. For most fundamental physical situations, particles obey C-symmetry, meaning that the laws of physics are identical for particles which have opposite charges (for this purpose, the opposite of a proton is an antiproton and not an electron; while the opposite of an electron is a positron (antielectron).) Not everything obeys C-symmetry, however. The lack of C-symmetry in the weak interaction led to the development of a more basic type of symmetry that is universal, known as CPT symmetry (charge-parity-time symmetry). --Jayron 32 11:20, 18 September 2018 (UTC)[reply]

The error is in assuming that the two types of charge are invariable. Bear in mind that quarks have electrical charges of +2⁄3e or −1⁄3e. Protons and electrons having opposite and equal charges has led to that being the unit of charge - but actual charge doesn't always have to be +1 or -1. Wymspen (talk) 10:16, 19 September 2018 (UTC)[reply]

Charge is still quantized, though. Historically, we picked the wrong thing to call the "1", but the entire system works (for example) if we had picked the charge of the down quark and called that "1". It's still quantized, and there is still a fundamental charge which all other charges must be a multiple of. It's just not "1" in our current system. --Jayron 32 11:13, 19 September 2018 (UTC)[reply]

"Wrong" is subjective. Free quarks don't exist below the Hagedorn temperature, so outside of high-energy physics we only care about the charges on electrons, protons, and other "stable" particles. It's simpler to use "1" for this; otherwise we'd be doing a lot of base 3 math. --47.146.63.87 (talk) 08:16, 21 September 2018 (UTC)[reply]

Although the negative and positive charges are equal and opposite fundamentally, as per the above discussion, in chemistry, it's quite often the case that the negative charges of the electron cloud are felt more strongly than the positive charges of the nucleus. This is because the electrons are on the outside, so they form a shield around the nucleus. This is discussed under the subjects of electron shielding and effective nuclear charge. The latter article shows that for neutral atoms, increasing charge of the nucleus by one results in less than one additional charge being felt outside the electron cloud. Neon for example has 10 positive charges (and 10 negative charges) but a charge of only +5.758 is felt by the outermost electrons. Handschuh-^{talk to me} 10:45, 22 September 2018 (UTC)[reply]

Addendum: it's not just that electrons are on the outside, but that they exist in shells around the nucleus. This is because electrons are fermions, and therefore the Pauli exclusion principle keeps them from all occupying the same quantum state, which bosons are free to do. --47.146.63.87 (talk) 06:04, 23 September 2018 (UTC)[reply]

Have there been any predictions/projections on when we will be able to regrow human skin and thus completely eliminate white scars?

Have there been any predictions/projections on when we will be able to regrow human skin and thus completely eliminate white scars? Futurist110 (talk) 20:01, 18 September 2018 (UTC)[reply]

Human skin does "regrow", but as scar tissue; there is research for "wounds to heal as regenerated skin rather than scar tissue":[12], but that doesn't cover already existing scars. 2606:A000:1126:4CA:0:98F2:CFF6:1782 (talk) 23:02, 18 September 2018 (UTC)[reply]

Biology is funny. I remember a time when I was 16 or so and managed to somehow slice or rip open the skin across my Achilles tendon on a rock, seemingly all the way to the fascia. It didn't hurt, and didn't bleed, and I didn't want the bother of a doctor, so I just closed it up a little and left it under a bandage; it healed without trouble with a fairly wide white scar. Years later, I couldn't find the scar at all. But another scar from a burn on a finger from that time never went away, though after many cycles of becoming aggravated and being picked at its appearance reduced a bit. We have an articles scar free healing and decent reviews are available, but it seems like there is a lot of randomness in the process still in need of explanation. Wnt (talk) 00:05, 19 September 2018 (UTC)[reply]

See [13]. 92.8.178.228 (talk) 10:41, 19 September 2018 (UTC)[reply]

I found the manufacturer who mentions CTGF, and cites [14]. The design of the modified asymmetric siRNA is given in this appendix. The actual substance is therefore the annealed combination of

cp - asiCTGF sense = mCUmUAmCCmGAmCUmGGmAA(s)mG(s)A(s)-chol

cp - asiCTGF antisense = UCUUCCAGUCGGUAmAmGmCmCmGmCmGmAmGmGmGmCmA(s)mG(s)mG(s)mC(s)mC-chol

Where mN = 2’ - OMe modified nucleotide, (s) = phosphorothioate, and -chol = cholesterol.

If this holds up, it is not merely a medical advance, but also a big technical step forward in siRNA technology, with applications to a vast number of target genes. And, this should be a type of drug fairly readily manufactured on an illicit basis by those with the will to do so, making it potentially accessible to the common people. Wnt (talk) 13:56, 19 September 2018 (UTC)[reply]

Would this also work for old white scars? Futurist110 (talk) 03:53, 20 September 2018 (UTC)[reply]

We have an unconfirmed report from the manufacturer that it works on a fresh wound in a rat. Everything else is fun... but speculative at this point. Unless someone tries the experiment I won't even have a guess what would happen there; I'm not very optimistic but you can look up CTGF and related articles and see what you think. Wnt (talk) 13:50, 20 September 2018 (UTC)[reply]

September 19

How to choose an expert?

If I want to solve an issue -- settling a dispute about an edit in an article in Wikipedia, deciding whether cell phones provoke cancer or taking homeopathic medication -- are we doomed to appeal to an authority to settle the issue? Wikipedia has a rather dismissive attitutde towards credentials, so, it makes the question even trickier. When we admit that we are not competent in a field, how to decide who is competent, when there's a huge body of knowledge in a science? --Doroletho (talk) 00:35, 19 September 2018 (UTC)[reply]

Wikipedia doesn't "choose an expert", it summarises what the majority of experts have published in WP:Reliable sources, giving both sides where there is wide disagreement. Dbfirs 06:15, 19 September 2018 (UTC)[reply]

The leap of faith that Wikipedia makes is that, while it takes an expert to appreciate the validity, limitations etc. of the expert consensus on domain Foo, it does not take one to know what that consensus is. And that is what we describe (alongside significant minority views, public perception yada yada). We proceed exclusively by "appeal to authority". Tigraan^{Click here to contact me} 09:07, 19 September 2018 (UTC)[reply]
I need to make one minor quibble, "dismissive attitutde towards credentials" is 100% wrong. Wikipedia has a strong respect for the writings of experts that have been published in reliable sources. Indeed, ALL of Wikipedia is designed to be referenced to the writings of highly credentialed people who have been scrupulously vetted and who's writings are considered highly reliable. What Wikipedia is (and is rightly so!) dismissive of is a) the claim that because a person in an argument says they have credentials, they should win any disagreement and b) that the existence of credentials (even if valid) in a discussion should override actual, published, reliable sources where the person fronting the argument disagrees with those sources. Wikipedia loves credentials, it just dismisses people who use claims of credentials to win arguments in opposition to what is written in reliable sources. --Jayron 32 11:09, 19 September 2018 (UTC)[reply]

We have an encyclopedia article: an expert ..."has intense experience through practice and education..." and "is widely recognized as a reliable source."

That lede paragraph summarizes it! Expertise is developed by studying, and is established by peer-review. Whether we are participating in editing or reading Wikipedia, or in any other aspect of our lives, we determine "expertise" by finding many other people who agree with us.

This may seem like an oversimplification; it may seem unstable or hazardous; but it works. Alternatives to this method have been proposed; you can study the theory of knowledge to learn about the meta-problem of trying to establish knowledge (and the related concept, "truth"), from first principles; but in short summary, even though many philosophers have proposed alternatives, Wikipedia is one exemplar of a working system in which all knowledge is established through community consensus - including the specific ouroboric knowledge about which members of our community carry even more knowledge.

Nimur (talk) 16:01, 19 September 2018 (UTC)[reply]

Society used to appeal to authorities to settle issues on all matters before the scientific revolution. For 300,000 years humanity has existed we didn't have cell phones, cars, satellites etc. etc., and that changed when the scientific revolution started about 300 years ago. The most important thing that allowed the scientific revolution to succeed was to stop to appeal to authority. Count Iblis (talk) 17:06, 19 September 2018 (UTC)[reply]

No, we still appeal to valid scientific authorities: Every individual person (like you, me, everyone else here) does not have enough minutes on earth to do every scientific experiment ever done. While what makes science different from other forms of knowledge-making is that one could re-do each experiment (and also that each experiment has the potential to disprove a hypothesis, what is called falsifiability, the ability of a hypothesis to be disproved by experimentation). What has changed is the type of authority upon which we appeal: the appeal to a scientific authority is still necessary, because we literally cannot expect every citizen to do every experiment themselves; the same applies to authorities in other field: we cannot expect every human to read every historical text ever written; but they should be able to check the sources of reliable historians. We still appeal to the authority of those scientists because they have a reputation of using valid scientific methods to make knowledge and we still appeal to the authority of historians because they have a reputation of using valid historical methods to make knowledge, etc. etc. The reliance on valid authority in knowledge building is necessary because no one human can build all of that knowledge on their own from first principles. At some point, they have to have reasons to trust that someone else is doing it right. --Jayron 32 17:20, 19 September 2018 (UTC)[reply]

Yes, we do need to put our trust in a system, as even scientists cannot go about verifying everything they need to know for their own research. However, this is then the system involving rigorous reviews and independent reproduction/verification of results, so it's not about trusting the judgment of particular individuals. If it's at all possible to have doubts about some result, then such doubts will be the subject of further research. So, it's far more about the whole process making sure that researchers are not going to leave any stone unturned, that allows people to have trust in the results of scientific research. Count Iblis (talk) 20:33, 20 September 2018 (UTC)[reply]

The traditional approach has been a combination of authority, jury, evidence, and democracy. People expect "good papers" and "good journals" to be run by "the right people", based on ad hominem considerations, but then allegedly random researchers (chosen by authority) review papers and decide based on the text, and then we review the papers by doing a literature search and seeing who is mostly believed.

The modern issue is that some trolls might generate more comments than everyone else put together. Papers and whole journals might be the blathering of artificial intelligence. Such mechanisms have the net effect of disrupting communication, so people retreat into "bubbles" by which they trust fewer opinions, even if less competent, to go through the mass of nonsense and try to pick out something that sounds logical and reasonable. But then there's also the issue that while in the past a forged figure might be crudely copied and pasted in multiple papers, now we can picture some entities generating convincing forged video, so certainly a good faked PAGE gel. So long as an honest mind trying to reconcile the logic behind the data can make sense of what is genuine, there might be hope, but how long can that last? After that, all communication is lost and humans are back to where they were before the invention of speech, but with a superior species of machines occupying their former niche. Wnt (talk) 14:08, 20 September 2018 (UTC)[reply]

That's the problem of knowledge making in general, and in the end following your train of thought leads only to solipsism, which while logically consistent is not a practical way to live one's life. As soon as one places trust in any concept which cannot be perfectly proven (including, even, what your own senses tell you on a daily basis), one must take some leap of faith that the information one is assuming is real is actually real. At some point, you have to just trust it, and you can set your own criteria for what is likely to be more trustworthy, but to follow perfect logic and demand that all information require perfect truth to be acceptable, ONLY solipsism works. --Jayron 32 16:49, 20 September 2018 (UTC)[reply]

It depends how much effort you want to put into it. The legal system has a highly-developed way of arriving at the truth. Cases are originally heard in a court of first instance. If there is any doubt you can appeal to a higher court, then a still higher court and so on. At the end of the process you get a well-referenced decision which is very unlikely to be wrong. 92.31.140.53 (talk) 15:08, 20 September 2018 (UTC)[reply]

Hmmm, I would have said something more like "fifty-fifty". Wnt (talk) 12:28, 22 September 2018 (UTC)[reply]

Regarding trusting experts and science see our article on argument from authority. --Modocc (talk) 16:40, 20 September 2018 (UTC)[reply]

type of turbine in a dam

I have a hydroelectric question about two dams in western Washington, both described in Wiki: the Upper Baker Dam and Lower Baker Dam. Are both dams equipped with Pelton impulse turbines? If not, what kind of turbines are in use? Thanks for your help! It's a wonderful service. Rossroderick (talk) 03:17, 19 September 2018 (UTC)[reply]

They're 300' dams, so that's enough head for Peltons to make sense. I can't find anything on-line about them to confirm this, although [15] contains this tiny cross-section image of the new 30MW Unit 4 which looks more like a Francis turbine. Andy Dingley (talk) 11:32, 19 September 2018 (UTC)[reply]

Are there any bacteria that are hydrophobic?

My understanding is bacteria in general all thrive in wet/moist conditions, so are there any bacteria that don't like water? Then, are there any bacteria that are neutral in water (don't actually thrive more). Otherwise, bacteria is generally 100% hydrophilic right. 12.239.13.143 (talk) 18:58, 19 September 2018 (UTC).[reply]

"Hydrophobic" and "hydrophilic" are not typically used to describe organisms. All known cells are bags of water, so in that sense (if you don't consider viruses and prions to be alive) you could describe all life as "hydrophilic", because all life needs water. But not all bacteria are adapted to wet environments. Bacteria or archaea live in every terrestrial environment we've checked, including bone-dry deserts, acid mine drainage, salt lakes, and rock miles underground. Bacteria adapted to those environments will often not do well in others because other bacteria will out-compete them. As you may see, the reason those terms aren't used is they don't have much descriptive power when you try to apply them to organisms. They're too reductive. Plus, it risks confusion with their typical usage in chemistry. --47.146.63.87 (talk) 06:45, 20 September 2018 (UTC)[reply]

Lipophilic bacteria may be helpful, although I think that article would benefit from some work. Klbrain (talk) 22:48, 22 September 2018 (UTC)[reply]

type of hydroelectric turbine in use

Yesterday I asked this:

I have a hydroelectric question about two dams in Western Washington, both described in Wiki: the Upper Baker Dam and Lower Baker Dam. Are both dams equipped with Pelton impulse turbines?

This was the very good answer:

They’re 300’ dams, so that’s enough head for Peltons to make sense. I can’t find anything on-line about them to confirm this, although [16] contains this tiny cross-section image of the new 30MW Unit 4 which looks more like a Francis turbine. Andy Dingley (talk) 11:32, 19 September 2018 (UTC)

I have since learned that the turbine vanes in at least one of the dams have streams of water directed at them, through nozzles, that are controlled by hydraulics, i.e., by oil under pressure controlling the motion of pistons. The hydraulics are used to determine the direction of the flow and possibly the pressure of the flow.

Would that information tend to indicate Pelton impulse turbines or the Francis turbine?

And a second question: Do you know which dam the new 30MW Unit 4 is installed in: the upper or lower dam?

Thanks very much.

Rossroderick (talk) 03:28, 20 September 2018 (UTC)[reply]

Atleast the technology of the last unit 4 turbine is pretty clear because of its unique feature of being "fishfriendly". All conventional hydro turbines are fischkillers and on top allow only one direction since no fish is fast enough to swim up in them.

That it is the newest also gives a clue, because altho it is one of the oldest turbine principles of all, it has only recently become very popular again in modern hydroelectric powerplant constructions.

They are called vortex-, low head- or very low head turbines (VLH-Turbines). Seems they are still so brand new and uncommon (altho i had already read about them (wrongly described) as "new innovation" 4-5 years ago) that we actually still dont have an article about them, nomatter they are definitely worth one. I am a little puzzled with the 2 dams tho because these vortex turbines actually dont need a dam and the mentioned sidenote about the benefit for the fish should mean there are 2 of these or the one in the lower dam somehow circumvents the upper to let the fish pass tru both. --Kharon (talk) 04:43, 20 September 2018 (UTC)[reply]

A Gravitation water vortex power plant is one of the types mentioned in the Low head hydro power article. DMacks (talk) 05:16, 20 September 2018 (UTC)[reply]

Construction- and engineering-firms still seem in a contest about how to call these. I learned about them under the name vortex hydro turbine. I am pretty sure many more will be build in the future because they are actually very simple and easy to build, yet surprisingly effective and versatile and on top very ecological. So guess some common name will crystallize out in some years. --Kharon (talk) 06:18, 20 September 2018 (UTC)[reply]

I'm kind of surprised they need a special turbine to spare fish. I mean, haven't any of these engineers heard of FACS sorting? :) Wnt (talk) 13:57, 20 September 2018 (UTC)[reply]

Lots of methods have been tried to reenable natural diadromous fish migration. Unfortunately only with limited success no matter the serious effort and investments. These new old vortex turbines actually promise a very good solution to that which is surprisingly cheap and effective enough for power generation on top. Besides Hydro power is pretty abundant anyway so dependent on POV it may actually look a bit silly to take such huge investments, just to tinker out a few more % efficiency. --Kharon (talk) 18:02, 21 September 2018 (UTC)[reply]

September 20

Particles, wood heating & diesel

Hello! The dieselgate has brought to light a fraud involving toxic emissions from diesel vehicles. In the case of fine particles, total pollution includes emissions from industry, transport, individual heating &c. How is each contribution calculated? If transport-related emissions have long been undervalued due to car manufacturers' fakes, what is the adjustment factor and have we not, for example, exaggerated the impact of wood heating? Thanks for your help, --methodood (talk) 10:34, 20 September 2018 (UTC)[reply]

Dieselgate redirects to Volkswagen emissions scandal. Is that what you're referring to? Also, where have you been for the last eight years. :) ←Baseball Bugs ^{What's up, Doc?} carrots→ 13:02, 20 September 2018 (UTC)[reply]

Hi Bugs! Can you give me the detail of the contributions of each pollutant before and after the revelation of the scandal, how it is calculated (and if the prorata didn't evolve, why ?) Thank you.--methodood (talk) 18:31, 20 September 2018 (UTC)[reply]

Dieselgate is only about NO_x emissions. Fine particle emissions were not involved. Ruslik_Zero 20:22, 20 September 2018 (UTC)[reply]

These numbers are all estimated (numerically projected) based on a few samples. If you manipulate some samples you of course also manipulate the whole picture and change the relation of all picture elements among each other. That does not mean you change every element and its own impact! --Kharon (talk) 22:54, 20 September 2018 (UTC)[reply]

Plants question.

If you bring a plant from the cold arctic, like coniferous trees, and bring it to the tropics, equatorial regions, will it be happy, or worse? Cuz I imagine the other way around is more painful, bringing a tropical plant to the cold arctic. So when you bring a arctic plant to the warm regions, with more sunlight, what would be the answer? If things like different soils play a role, then what about if you bring the same soil and so the only changing variables are temperature and latitude? Thanks. 12.239.13.143 (talk) 21:21, 20 September 2018 (UTC).[reply]

Depends. I don't have an answer to your actual question, but will note that the equator is not all happiness and sunshine from every plant's perspective. Heat and high humidity are downright stressful for some of them. Someguy1221 (talk) 21:48, 20 September 2018 (UTC)[reply]

Not all but many plants are specialized on specific environments and according conditions. Arctic plants for example tend to have a very slow metabolism that probably cant "deal" with the energy volume of sunlight in warmer regions, just like you cant put a Seacow into the Rapids and expect it to survive and reproduce there. --Kharon (talk) 23:14, 20 September 2018 (UTC)[reply]

Do yo mind providing any source to your claim that "Arctic plants for example tend to have a very slow metabolism"? Is that something you can cite or just imagined to be the case?

Indeed, arctic plants very fast development, high rates of metabolism concentrated in a short period of time, when there's sun available.

In contrast, in season-less tropical climates, plants can compensate for low rates of metabolism by having long durations of activity. There's plenty of sun for that.

In any of both cases, the evolutionary adaptation is the lowest temperature at which new cells can be generated.Doroletho (talk) 01:50, 21 September 2018 (UTC)[reply]

According to this source "the vegetation of the taiga is vulnerable because of its low rate of metabolism and biological activity due to cold temperatures". Mikenorton (talk) 09:16, 21 September 2018 (UTC)[reply]

But there's a question of chicken versus the egg: does their metabolism appear to be slow because of the reduced sunshine for much of the year or is it really slow? It's a question of lack of resources versus internal mechanisms. Anecdotally, northern plants are certainly capable of rapid growth when conditions are ripe (broadly similar to a desert bloom) and the stunted "trees" around the treeline also grow bigger and faster further south. Whether they're genetically tuned to grow differently is really the crux of the question. Matt Deres (talk) 15:10, 21 September 2018 (UTC)[reply]

Sunshine seems less important than temperature because you find the very same strategy and adaption for example in Greenland sharks who are even apex predators aka Carnivores in their environment, thus hardly dependent on allot of sunlight, have a even extremely slow metabolism and obviously no interest to leave their very cold environment. --Kharon (talk) 17:11, 21 September 2018 (UTC)[reply]

Wait a minute you're comparing plants to animals here?? Plants need sunlight to photosynthesize, animals do not. 67.175.224.138 (talk) 05:57, 22 September 2018 (UTC).[reply]

Hence: asking for real sources rather than "I imagine that" is the way to go. --Doroletho (talk) 13:01, 22 September 2018 (UTC)[reply]

Okay I asked 2 plant professors this question. 1st 1 said for coniferous trees, yes it can as it is strong enough to live in both environments. But not all Arctic plants. Basically his ultimate answer was "depends on the plant." A 2nd 1 predicted that if you move a plant from the Arctic to the tropics, it will have problems where it loses a lot of water. But I ask what if it were moist, rainfall environment, so he goes on with other factors like being exposed to different kinds of bacteria and fungi. So it seems to me, that placing a plant from a wet environment to a dry environment is a bigger issue - so now my 2nd question is - what happens if you bring a desert plant like cacti into a moist, rainfall environment? I'll later ask around about metabolism. 207.140.218.10 (talk) 17:40, 21 September 2018 (UTC).[reply]

Many (but not all) cacti will suffer root rot if they are in a wet environment. I wouldn't even try to grow a cactus where I live with a hundred inches of rain a year. Even Mediterranean plants tend to rot here, but conifers grow well. Here is a Quora answer about cacti. Dbfirs 19:39, 21 September 2018 (UTC)[reply]

You could probably grow them indoors as long as you don't overwater. --47.146.63.87 (talk) 06:50, 23 September 2018 (UTC)[reply]

Well, yes, I do grow small ones indoors where they seem to thrive on neglect most of the time. Dbfirs 10:20, 23 September 2018 (UTC)[reply]

Not about conifers, but here's some comments from the University of Florida (http://gardeningsolutions.ifas.ufl.edu/plants/edibles/fruits/chill-hours.html) regarding deciduous fruit trees - "In order to bloom in spring, deciduous fruit trees like peaches, plums, and nectarines all must go through the plant equivalent of a long winter's nap. They need a dormancy period with a certain number of chilling hours, when the temperature drops below 45 degrees Fahrenheit. The exact number of chilling hours depends on the fruit tree variety, but it can be anywhere from a hundred to more than a thousand....." So, your peach tree might survive in the tropics, but may not set fruit. HiLo48 (talk) 22:47, 22 September 2018 (UTC)[reply]

September 21

Baker Dam turbines, continued dialog

In response to the dialogue about dams on Baker Lake.

But these are NOT low-head dams. The new low-head turbine technology is simply not required, and there are tradeoffs if it's used unnecessarily. And if you look at satellite photos of Baker lake on Googlemaps, you can clearly see the special nets employed to capture fish and move them around the dam. And you can read about them as well, in Wiki articles.

If the Baker-dam turbines are EITHER Pelton OR Francis, what would they likely be? What’s your best guess, and can you justify making it?

Thanks again!Rossroderick (talk) 00:41, 21 September 2018 (UTC)[reply]

Several sources list head ranges from 200 or 500 metres up to 1500 metres for Pelton turbines, and from 20 or 80 metres up to 500 or 750 metres for Francis turbines ( https://www.slideshare.net/BKLR/hydraulic-turbines, http://164.100.133.129:81/econtent/Uploads/16-Hydraulic%20Turbines%20%5BCompatibility%20Mode%5D.pdf and https://www.youtube.com/watch?v=k0BLOKEZ3KU&vl=en ). It would also depend on flow rate, see the "Hydraulic turbine selection" graph at page 40 of the second source. So I would say a Francis turbine. Prevalence 02:28, 21 September 2018 (UTC)[reply]

When this query was first posted, I did quite a bit of digging around, but decided not to post with a non-definitive reply. But since you ask for "best guess" (with choice limited to Pelton vs. Francis), here's my evaluation: in 1925, Francis turbines were installed; by 1988 they were Peltons. The latter is supported by your description of the hydraulic piston mechanism. The Pelton impulse-jet uses a synchronization device (perhaps using pistons) which I equate as sort of the inverse of the mechanism developed in WW1 for machine guns on airplanes. On airplanes, the machine guns were synchronized such that the bullets would miss the propeller blades, whereas the Pelton device would synchronize the water-jet impulses such that they would hit the turbine blades -- in just the right spot for maximum efficiency. If need be, I could peruse my internet history and (hopefully) find photos/documents that lead me to this (e.g: archived 1925 photo of newly-installed turbines on one of the Baker dams that were not Pelton, probably Francis and archived government document that evaluated Peltons, noting their installation within the system that includes the Baker dams -- but not specifically those dams). So, my "best guess" is that the current primary turbines are Pelton, augmented by some "fish-friendly" system. —2606:A000:1126:4CA:0:98F2:CFF6:1782 (talk) 03:38, 21 September 2018 (UTC)[reply]

Its very odd that no one, not the owner nor management nor locals made any effort to offer some more detailed documentation.

Additionally, after trying to research about it for some time, it also struck me that homeland security may just now look over my shoulder "virtually live" and ask themselves why the heck i am interested in some power station in the state of Washington. So in conclusion let me forward that! Why the heck are you? --Kharon (talk) 17:28, 21 September 2018 (UTC)[reply]

I can't find any sources to support the general idea that the water flow is pulsed in Pelton designs. The flow can be increased or decreased depending on output demand, but everything I've seen is that it's essentially held constant at any given time. Sounds like a possible confusion of the idea of pulse vs impulse (physics)? DMacks (talk) 17:31, 21 September 2018 (UTC)[reply]

The transfer of water flow from each bucket to the next one of a Pelton wheel is modelled by design to minimise turbulence which represents wasted energy and vibration; note the shaped leading edges of the buckets here. The idea of externally interrupting the flow between buckets invites causing Water hammer, an extremely dangerous phenomenon at the high levels of kinetic energy involved in hydropower stations; witness the devastation in the 2009 Sayano–Shushenskaya power station accident. DroneB (talk) 17:06, 23 September 2018 (UTC)[reply]

September 22

Valence Bond theory vs Molecular Orbital theory descriptions of O₂

I am reading this paper on the use of VBT and MOT in teaching chemistry, and I'm having trouble getting past the first paragraph. Specifically, the following excerpt is what I'm struggling with:

"MO theory is often presented as a superior or more advanced theory citing “failures” of VB such as the paramagnetism of O₂ and the explanation of excited electronic states. However, a more in-depth application of VB (1) shows that resonance between two paramagnetic structures with two 3-electron π bonds (Figure 1A) is more stable than resonance between two diamagnetic spin paired structures each with a 2-electron π bond and a 4-electron repulsion (Figure 1B)."

I don't understand several points about this. Firstly, isn't the double bond in dioxygen a sigma bond and and pi bond, not two pi bonds as per the text? I understand that the two bonds are actually equivalent (not one sigma and one pi, but two equivalent bonds of mixed character), but to make that point clear you'd need to invoke hybridization, and in their description and drawing they haven't done so.

Secondly, don't bonds involving three electrons imply that at least two electrons would have the same set of quantum numbers and therefore be in violation of the Pauli principle? I've never heard anything about 3 electron bonds before, and I don't understand how they can be made to fit with either VBT or MOT as both are quantum based theories and as such must conform to Pauli. Figures 1A and 1B don't help me much either. Assuming that the solid line between the nuclei indicates a sigma bond, figure 1A seems to show a triple bond between the atoms. The existence of two p orbital on each atom also seems to indicate sp hybridization, whereas O₂ has sp² hybridization. Actually, a VBT description that explains the paramagnetism of O₂ would make more sense to me if they showed 2 sp hybridized O atoms triply bonded (1 sigma bond between the sp orbitals, and two pi bonds between p orbitals) with an unpaired electron in each of the remaining sp orbitals. This would not account for the lone pairs though, and would imply a far shorter bond length. Handschuh-^{talk to me} 09:39, 22 September 2018 (UTC)[reply]

"O₂ has sp² hybridization" is either circular reasoning or an unsupported underlying premise:) You are rightly concerned about putting a third electron into a single π molecular orbital, but when you add two p atomic orbitals, you get both a π and a π* and that latter can hold up to two more electrons. If you hybridize two p, which can hold a total of 4, your result can also hold a total of 4. Their diagram 1A represents two p orbitals interacting rather than a single unified π. They casually call it "π", but it's really also π* (which also actually does have π symmetry). So there are two sets of π/π* in addition to the σ, but each bonding π (populated by 2 electrons) is weakened by 1 electron in its associated antibonding π. That means each of the two π/π* has net effect of approximately "half bonding". So "1σ+2[half-π]" rather than "1σ+1π" still gives a net appearance of 4 bonding electrons exactly as "O=O" represents. Our triplet oxygen discusses the MO approach in detail and also links to the idea of three-electron bonds. DMacks (talk) 10:31, 22 September 2018 (UTC)[reply]

"when you add two p atomic orbitals, you get both a π and a π* and that latter can hold up to two more electrons"

Except this is supposed to be a VBT description of the bonding. Bonding and anti-bonding orbitals are a MOT concept..aren't they? Handschuh-^{talk to me} 10:50, 22 September 2018 (UTC)[reply]

No, at the introductory level we usually gloss over that aspect, but Modern valence bond theory is entirely compatible with MOT, and uses many of the same tools to deduce electronic properties. --Jayron 32 23:08, 22 September 2018 (UTC)[reply]

Also, as shown in the paper, especially the diagram, it isn't a 3-electron, 1-orbital bond, it's a 3-electron, 2-orbital bond; that is you have 3 electrons distributed (via Resonance between two perpendicular pi-bonds). In the case between VBT and MOT here, the difference is in the explanation of the paramagnetism: VBT explains it via resonance, MOT explains it via bonding/anti-bonding orbitals. Either way, however, Pauli is preserved, look at the diagram on the right: You have two perpendicular p-orbitals, and neither ever has more than 2 electrons in them. Ultimately, however, they are both still useful theories which is why we keep them both: VBT is powerful in explaining geometry (angles, positions, and bond lengths), whereas MOT is useful in such matters as visualizing energy and bond order. Each can kind-of come up with explanations the other is better at (i.e. "resonance", which is still an inelegant kludge that MOT avoids entirely), but the point of the paper is that BOTH theories are valid because even VBT can explain observed behavior. --Jayron 32 23:16, 22 September 2018 (UTC)[reply]

Well, if VBT can include bonding and anti-bonding orbitals then I don't even understand what the distinction between the two theories is. As I understand VBT, a bond is created by overlapping two atomic orbitals. This allows the electrons to be counted as being in atomic orbitals from both atoms in the bond. In the diagram, no atomic orbital has more than 2 electrons, but two atomic orbitals are indicated to be bonding i.e. overlapping to form a bond with a total occupancy of 3 electrons.

Secondly, if VBT is only able to accurately describe the bonding of dioxygen after we update the theory with concepts borrowed from MOT, then that doesn't say much for the paper's argument that VBT is just a good a description of the phenomenon. Handschuh-^{talk to me} 00:10, 23 September 2018 (UTC)[reply]

Whatever this is, it is not the familiar approach. The original cited article is [16] - I have to go, so I haven't looked to see if it's in Sci-Hub. Wnt (talk) 12:48, 22 September 2018 (UTC)[reply]

Species identification (Unknown spiders)

2 unknown spiders for Species identification:

Based on uploaders talk page, most probable region is North Eastern US, maybe New York?

(Aside: A photo subject identification refdesk would be useful.) ShakespeareFan00 (talk) 10:30, 22 September 2018 (UTC)[reply]

For photo identification the TinEye service, an example of Content-based image retrieval, is useful for checking whether an image is already on the web, though it cannot interpret an image. DroneB (talk) 11:07, 22 September 2018 (UTC)[reply]

The lower one looks like a Dolomedes tenebrosus - in fact they may both be. Mikenorton (talk) 12:25, 22 September 2018 (UTC)[reply]

When An Idea appears on your conscious mind

What makes ideas pop up into your conscious mind? Is there a brain mechanism for that? — Preceding unsigned comment added by 37.252.180.177 (talk) 23:11, 22 September 2018 (UTC)[reply]

See this for example. Before the idea becomes conscious it is sometimes called preconscious though our article uses that term in a somewhat different way. 173.228.123.166 (talk) 00:59, 23 September 2018 (UTC)[reply]

Yes, the word did not pop up into my mind when I wrote the question. But it remains unanswered. There is probably loads of preconscious processing. How come only some become conscious? --31.4.136.202 (talk) 09:52, 23 September 2018 (UTC)[reply]

I have had occasions where I would need for some reason to remember some obscure fact, like who was some unsuccessful presidential candidate’s vice president candidate, knowing that I knew the answer at least during the campaign. Hard concentration does not bring the answer to mind, but I can leave the search to the unconscious processes and go on to to some other task. After thirty seconds or so the answer pops up without any conscious effort at all. It is literally like the file search is being done by a separate mental process from conscios awareness or mental effort. Edison (talk) 15:54, 23 September 2018 (UTC)[reply]

Related may be Working memory#Relation to attention. I cannot remember the name of another possibly related bias (similar to confirmation bias), although we tend to notice what we expect to see or what we're looking for. We routinely think and remember things that are not considered immediately important and quickly discard, but if such normally mundane event is recently seeked for, we'll tend to focus on it (or finally remember what was "tagged for retrieval"). An example is when we notice we need to buy an item (it may have recently stopped working, or a newly perceived need), then we start noticing it in stores and ads, although we never would normally care about the particular item... But that's of course not explaining the internal details of preconscious processing, a lot of which is still mysterious... —Paleo Neonate – 17:23, 23 September 2018 (UTC)[reply]

See subliminal advertising. 92.31.140.53 (talk) 18:12, 23 September 2018 (UTC)[reply]

September 23

5 ARIs and erectile issues.

Why do 5 Alpha Reductase inhibitors cause erectile dysfunction and are they reversible for Finasteride and Dutasteride? — Preceding unsigned comment added by 103.15.60.45 (talk) 06:08, 23 September 2018 (UTC)[reply]

See 5α-Reductase inhibitor. And if you're concerned, see your doctor. ←Baseball Bugs ^{What's up, Doc?} carrots→ 06:22, 23 September 2018 (UTC)[reply]

I feel the link given gives a very vague answer. I want a more incisive one. — Preceding unsigned comment added by 103.15.60.45 (talk) 06:28, 23 September 2018 (UTC)[reply]

Dihydrotestosterone § 5α-Reductase inhibitors goes into more detail. --47.146.63.87 (talk) 06:49, 23 September 2018 (UTC)[reply]

Still not enough to describe the effect on penile muscle contractile issues. — Preceding unsigned comment added by 103.15.60.45 (talk) 07:46, 23 September 2018 (UTC)[reply]

If you are asking for a concrete case like "when used for few years and five months respectively" it's difficult to answer, unless for a doctor, who meets the patient in person. --Doroletho (talk) 10:55, 23 September 2018 (UTC)[reply]

Ok... please remove that time period. Can the effects be reversible? — Preceding unsigned comment added by 103.15.60.45 (talk) 11:57, 23 September 2018 (UTC)[reply]

3d screen, made of See-through displays

If you stack transparent LCDs, do you get a 3d screen? It would be a rather expensive toy for consumers, but could this work? Doroletho (talk) 10:53, 23 September 2018 (UTC)[reply]

Yes it works but Liquid-crystal displays do not emit light so you would have to arrange adequate illumination of the stacked screens, and LCDs have a limited viewing angle so you cannot achieve a full walk-around stereoscopic effect. Unless you really want to use a big stock of LCDs with all their associated connectors, wires, circuit boards and power supplies, first review the alternatives at the end of the article Stereo display. DroneB (talk) 15:51, 23 September 2018 (UTC)[reply]

Several famous projects using layered displays have come out of the MIT Media Lab and have been presented at SIGGRAPH and elsewhere. For example:

Tensor Displays
Kinetic Blocks and related tangible displays
"HR3D" displays using stacked displays

...and so on.

The ideas are neat but the execution is usually limited by several factors: most of these kinds of demo projects haven't gone anywhere because they're just not very useful - and once the innovative novelty wears off, even researchers lose interest. It's pretty unlikely that hobbyists or companies that target mass-market audiences are going to build anything better - because as soon as you add the extra constraints of cost, reliability, manufacturability, and compatibility, the technology has no clear net advantage over conventional displays.

Here's a review article: Three-Dimensional Displays: A Review and Applications Analysis (2011), which was featured in IEEE's Transactions on Broadcasting.

Nimur (talk) 17:38, 23 September 2018 (UTC)[reply]