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January 20

Blood and wounds

Why is coagulated blood the best protective layer for a wound to crust (to skin over)?

Additionally, what about blood from another body, placed on the wound that tries to skin over? 185.27.105.90 (talk) 08:34, 20 January 2017 (UTC)

Since coagulation developed through evolution, it doesn't need to have anything do do with being the best. It's just what we got. Makes sense - coagulated blood is tough, but a bit flexible, and it's right there anyway after a wound. As for someone else's blood? Sounds like an excellent way to spread a bloodborne infection. Better to stick with sterile methods of wound bandaging. Someguy1221 (talk) 10:25, 20 January 2017 (UTC)

Per Someguy1221, evolution doesn't produce the "best" in a Panglossian sense, which would imply that it was under some intelligent control. Evolution produces better traits, in a very rough sense. It actually produces entirely random traits, and over time, the better traits will tend to edge out the worse traits, but there's no plan involved. Stuff happens, and if it works better than what is already existing, it tends to keep working until it isn't better anymore. --Jayron32 13:11, 20 January 2017 (UTC)

Given an infinite amount of time, evolution should produce the best possible result. But, of course, we don't have an infinite amount of time. StuRat (talk) 16:35, 20 January 2017 (UTC)

That might be true if the world was a constant. It is not. Rather, it is constantly changing and so there is always another "best" solution just around the corner. DrChrissy ^(talk) 19:01, 20 January 2017 (UTC)

Yes, you would need an infinite amount of time at each set of conditions to get the perfect solution for that set. StuRat (talk) 02:27, 21 January 2017 (UTC)

I believe that you are mistaken. Evolution typically only finds the local maximum. For example, squid eyes have the blood vessels on the back side, while human eyes have them on the front side, causing blind spots and other less-than-ideal effects on vision. Evolution is very unlikely to result in human blood vessels moving to the rear of the retina, because there is no minor change that cause a minor improvement. Another classic example is the panda's thumb. --Guy Macon (talk) 19:05, 20 January 2017 (UTC)

Given an infinite amount of time, you would eventually get "mutation combos", where many traits change at once. In the case of the eye, all the mutations required to move the blood vessels to the other side would eventually occur all at once, in a single individual. (Yes, it's like monkeys typing at random eventually typing a work by Shakespeare, in that it would take very long time.) StuRat (talk) 02:27, 21 January 2017 (UTC)

Are you suggesting that one day a horse-like female gave birth to a baby that had a 2 m neck and suddenly we had giraffes? DrChrissy ^(talk) 19:13, 21 January 2017 (UTC)

No, but given an infinite amount of time it would happen. You seem to be unfamiliar with the concept that over an infinite time period anything that can possible happen will happen, even incredibly unlikely events. See infinite monkey theorem. StuRat (talk) 01:39, 22 January 2017 (UTC)

You seem to be unfamiliar with the concept that the evolutionary pressures on an animal are in eternal flux - there are no constants. Comparing evolution with the infinite monkey theorem is flawed because the latter has a constant - the works of Shakespeare. Evolution does not work in this way. It does not have a template which it is working towards. There are many other (biological) factors to be considered. For example, in the farcical example I gave above about a horse-like animal giving birth to a giraffe, this simply would not happen because offspring with a 2m neck would kill the mother before birth. So, no giraffes from a one-off series of multiple mutations. So are you suggesting that if a suit of metal armour is the best protective mechanism, given infinite time, prey animals would evolve a mechanism of producing a metal suit of armour? DrChrissy ^(talk) 18:43, 22 January 2017 (UTC)

I had a totally different interpretation of the question, I thought it was just about how wounds heal, and didn't get hung up on "best". Rather than talk of evolution, I'd suggest OP read up on scab formation and wound healing. Here [1] is a very good general reference on the process of wound healing and treating wounds, that is more reliable than our articles. SemanticMantis (talk) 17:46, 20 January 2017 (UTC)

For the question "Can we use blood from person A to help heal a wound on person B?" -I'm not sure, but it's certainly not impossible, though there may be risks, as mentioned above. However, there is some precedent for using a patient's own processed blood to tread wounds. Here [2] is a 2010 review article about the use of platelet-rich plasma to treat wounds, including wounding occurring as part of surgery. The "platelets initiate wound repair by releasing locally active growth factors". We do use blood transfusions between people all the time, so it's not like infectious disease completely prevents us from using one person's blood to help another. SemanticMantis (talk) 17:48, 20 January 2017 (UTC)

Blood type could matter. (That's fairly basic stuff, but I see no reason to assume the OP knows about it.) Tigraan^{Click here to contact me} 14:20, 21 January 2017 (UTC)

You also have no reason to assume I was not aware of this basic stuff (hemm...really basic...). I was only asking about coagulated blood as a protective layer for a wound that tries to heal. As for the blood type, you might assume I was asking about someone else's (coagulated) blood of the same blood type, and again: as a protective layer only. 185.27.105.90 (talk) 17:42, 21 January 2017 (UTC)

Rant by TigraanClick here to contact me 19:00, 21 January 2017 (UTC)

If you had not been aware of blood groups and none had mentioned it, you would have left just as unaware. What you consider "really basic" is known only by those who have had a decent education. I suspect that among citizens of Zimbabwe, where according to our article the literacy rate is about 85%, more have access to Wikipedia's reference desk on a smartphone with internet than to proper biology courses at school. The assymetry between assuming knowledge when there is not and the reverse (which causes in the worst case a few more bytes on Wikimedia's servers and hurt egos) justifies to assume the latter unless the question justifies it. You have described it as a "fairly basic stuff", and I only agreed. However, I don't agree with you about the assymetry: In my opinion, it's entirely symetrical. 185.27.105.90 (talk) 20:14, 21 January 2017 (UTC)

Note: The OP is fooling around with his signatures. He's now editing as 185.27.105.82 (talk · contribs) but keeps erasing that fact. ←Baseball Bugs ^{What's up, Doc?} carrots→ 19:04, 21 January 2017 (UTC)

Since the address is in a close IP range, I don't think such "anti-sockpuppetry" deserves any blame. It may be harder to follow for future page history archeologists, but it is arguably better to follow the discussion. Tigraan^{Click here to contact me} 21:25, 21 January 2017 (UTC)

Exactly.

Sincerely, my aim was "anti-sockpuppetry" (after my computer lost my first IP), just to make the discussion easy to follow. 185.27.105.90 (talk) 10:29, 22 January 2017 (UTC)

You could simply start each comment with "OP here" or words to that effect. Then there should be no confusion. ←Baseball Bugs ^{What's up, Doc?} carrots→ 14:20, 22 January 2017 (UTC)

• StuRat's claim that an infinite amount of time, even when qualified, would lead to perfection is false, a layman's simplification. Evolution is both random and historical. GM is correct that it is largely limited to local maxima. The ontogeny of an organism depends on the matter it has to work with. This is why humans still develop gill arches as embryos, even though a smart designer would have the organsof the ear and throat develop directly.

Also, there is no way for macroorganisms to develop wheels for limbs, even though they might be ideal for locomotion in certain environments.

Look at the pathway of the laryngeal nerve of the giraffe, which travels twice the full length of the neck. In short-necked animals this design fluke is not obvious, but there is no way for the giraffe to overcome this obvious imperfection given they evolved from short-necked ancesstors and are stuck with that developmental path.

Finally, the closest you come to "perfection" in palaeontological history is the dinosaurs, but the Chixulub impactor basically killed off anything over a certain mass or inability to burrow or survive in the water. No matter how well adapted Tyrranosaurus was, it wasn't evolved to handle meteoric incineration.

μηδείς (talk) 01:23, 24 January 2017 (UTC)

Dispersion of atmospheric greenhouse gases

Is it potentially feasible to disperse or dilute excessive greenhouse gases (including CO2) by releasing more oxygen/other gases to the atmosphere (and thus eventually offset the emissions to counter global warming)? Perhaps this could be done regularly. Thanks.--93.174.25.12 (talk) 13:19, 20 January 2017 (UTC)

No, because:

(a) This would produce an overall thicker atmosphere, which would itself increase global warming – all gases have some greenhouse effect, it's just that some of them, like carbon dioxide and methane, have much more effect per molecule (so to speak) than others like oxygen and nitrogen.

(b) To have any significant effect, vast quantities would be needed, far more than we could possibly generate. To dilute the present excessive carbon dioxide level (approx. 400ppm) caused (we mostly think) by human agriculture and industry back to its previous level (of approx. 200ppm – exact numbers don't matter, so don't let's quibble *), you would have to roughly double the volume of oxygen and nitrogen. Where are you going to get a whole second Earth's worth of atmosphere?

(* NB: our article takes a pre-industrial starting point of 280ppm in 1750, but recent studies suggest that farming practices since the beginning of agriculture had by that time already contributed to a significant rise, hence my taking 200ppm as a mathematically convenient approximation). {The poster formerly known as 97.81.230.195} 94.12.94.189 (talk) 15:15, 20 January 2017 (UTC)

• One might argue that if we had the magical portal that allows to conjure up oxygen and nitrogen from the netherworld and pump it into the atmosphere, atmospheric escape would allow the total mass/volume/whatever of atmosphere to stay roughly constant by sending the surplus to space. I have no idea whether that argument is actually supported by the math, but it is at least within the realm of possibilities.

Of course, the big problem is point (b) - we don't have a portal to the netherworld, nor any industrial process that emits enough gases (let alone the ones we want) to double Earth's atmosphere. Tigraan^{Click here to contact me} 16:16, 20 January 2017 (UTC)

Even if we could dilute the concentration of carbon dioxide, hypothetically by doubling the total quantity of gas in the atmosphere - the outcome would be very hard to predict. Concentration is not the only parameter that affects the greenhouse effect or the average planet surface temperature. The greenhouse effect is driven by many factors, including the total optical depth of the atmosphere at particular infrared wavelengths. Diluting the greenhouse gases, without actually reducing the total quantity, might make for some really complicated dynamics - it might redistribute where the heat goes, and where it gets reabsorbed and recirculated - but it's not clear that we can draw a straightforward conclusion about how it would affect the climate. Bluntly: diluting the CO2 concentration by increasing the other atmospheric species might make the greenhouse effect stronger, weaker, or might have no change - and that complete non-answer is probably the most scientifically accurate conclusion we can draw!

You'd have to do some very sophisticated research on atmospheric modeling to figure out what would happen; and because we have very little useful data about how hypothetical atmospheres would behave, we don't have a great wealth of data to inform our models and figure out where they go awry.

For what it's worth, I spent all weekend learning about the Skew-T/Log-P approach to plotting and analyzing weather. Here's a great resource on Skew-T Log-P Diagrams from the National Weather Service; here's the current database. Anyone want to take a stab at analyzing how concentration and total quantity of our most abundant greenhouse gas, water vapor, affects the weather? Hint: we measure both - TPW and RH - and feed both into our most accurate models, including the NAM and the HRRR....

...and even then, I can't predict with perfect certainty whether it's going to be warm or cold, wet or dry, even in the short term. As a bike commuter, this uncertainty is troublesome - as an aviator, this uncertainty is a factor in my decision-making - as a scientist, it gives me great insight into the difficulty faced by medium- and long-range climate modelers.

The take-away message is that atmospheric dynamics is non-obvious - simple stimuli yield complicated behaviors. Dramatic changes - like changing the total quantity of gas in our atmosphere - start to fall outside of our established models, and responsible scientists won't make strong predictions about what would happen if we hypothetically changed our atmosphere in a way that is so far from physical reality.

You might be able to find great resources on planetary dynamics modeling if you extend your literature survey to include scientific study of planets-other-than-Earth. Here's a fun research paper that clearly resounds in the shadows of Carl Sagan's excellent book, Pale Blue Dot, and his 1993 paper A search for life on Earth:

• Earth as an Extrasolar Planet: Earth Model Validation Using EPOXI Earth Observations (2011).

Look how hard it is to characterize a planet when you have even a few percentage points of uncertainty about its atmospheric parameters!

Nimur (talk) 20:21, 20 January 2017 (UTC)

BTW although as mentioned above simply adding more gases isn't considered a viable or useful proposition, Climate engineering via Greenhouse gas removal including Carbon dioxide removal and Carbon sequestration is at least considered potentially feasible enough to have some research. As our articles mentions, although there is some overlap with Carbon capture and storage and distinction is sometimes made between projects aiming to capture carbon dioxide or carbon once after it's released to the atmosphere versus during production. Nil Einne (talk) 22:51, 20 January 2017 (UTC)

There is no relevant dilution effect here. The gases in the atmosphere can be treated to a very good approximation as independent components, they satisfy the ideal gas law to a very good approximation, the partial pressure of each component equals the concentration (molecules per unit volume) times Boltzmann's constant times the absolute temperature. So, the CO2 in the atmosphere is not going to behave differently just because you put in a lot more oxygen or nitrogen. This means that you're not going to change the mean free path of infrared photons (they have very little interactions with diatomic molecules), so they'll still escape to space from the same mean free path into the atmosphere as before. If you instead increase the CO2 concentration, you're going to reduce this mean free path, so the photons escaping into space will on average come from higher in the atmosphere. If you then balance this energy loss with the absorbed energy from from the Sun and take into account that the escaping photons are in thermal equilibrium with the part of the atmosphere from where they are escaping and that its colder at higher altitudes, then you'll find that the temperature at the surface will increase. Count Iblis (talk) 00:33, 21 January 2017 (UTC)

...and by direct application of the Stefan-Boltzmann equation in tandem with the solar constant, the effective planetary temperature of Earth is guaranteed to oscillate around a stable equilibrium irrespective of any other atmospheric condition and ... hence global warming is a complete myth! In case this isn't obvious, I'm being facetious. Global climate does change - and we know it changes - and these changes are hard to predict because they depend on so many deep and non-obvious interconnections between physical and chemical processes. We can not draw simple conclusions about planet-scale behaviors by naively applying equations from high-school physics. The atmosphere is really complicated, and the experts who spend their careers studying it generally agree that our models are only accurate within certain bounds. The OP asked us for references on atmospheric modification. I don't think you'll be able to find a single peer-reviewed paper that attempts to predict Earth surface temperature trend after applying some hypothetical process to dilute the greenhouse gas species by anthropogenically increasing the quantity of inert gas species. This kind of modeling work is interesting to geologists, planetary scientists, and so on; and in a world where all our information about the atmosphere comes from a single pixel, we can make fantastic speculations about atmospheric chemistry and temperature! But we have to be responsible: when we speculate about an environment so different from the empircal observations of our own atmosphere, our error bars are huge. Per the paper I linked earlier, if you use overly-simplified physics for a hypothetical atmosphere, your temperature estimates can and do err by hundreds of kelvins. If we model Earth's surface temperature dynamics for the proposed hypothetical atmosphere, the surface temperature will probably fall somewhere between zero and a thousand kelvins, if there is even a planetary surface anymore! One cannot casually change the stoichiometry of an entire planet! As we already know, Earth's climate is dramatically affected even by a tiny atmospheric change, such as the carbon-dioxide emitted by normal biological human behaviors - including, but not limited to, technological industrialism. We don't know what would happen if our anthropogenic atmospheric changes were millions of times bigger - and our best scientists don't even try to predict it.

Nimur (talk) 18:44, 22 January 2017 (UTC)

Mathematical physicist Freeman Dyson, FRS questions the mathematical models used to predict global warming on the grounds that necessary data to support global warming are not available, having created similar models to estimate the Earth's environment after a nuclear war for thirty years while working with Los Alamos National Laboratory and the JASON group of the Institute for Defense Analysis. However, he agrees that continued use of petroleum and other hydrocarbons from drilling is bad for the environment and has proposed intensive and vast planting of fast-growing trees to sequester carbon dioxide from the environment. He also predicts that these trees can be genetically altered to serve as an interim fuel source to replace petroleum and natural gas. loupgarous (talk) 21:15, 24 January 2017 (UTC)

January 21

How long ago was there a year when the global average temperature on Earth was as high as it was in 2016?

Is it likely that there existed such a year in the present interglacial or do we need to go all the way back the previous interglacial (which was quite a bit warmer than the present one) that ended 114,000 years ago? Count Iblis (talk) 00:51, 21 January 2017 (UTC)

The margin of error in the Holocene temperature reconstructions is large enough that the answer is "probably not, but we don't really know for sure." Not very satisfying but that's where we are. The likeliest time for a temperature as warm as 2016 would be the period following the rebound from the 8.2 kiloyear event. Shock Brigade Harvester Boris (talk) 00:59, 21 January 2017 (UTC)

Agreed with Shock Brigade Harvester Boris. Holocene climatic optimum has additional context. Matt Deres (talk) 14:13, 22 January 2017 (UTC)

This is a great question. First: let's clarify exactly what we mean when we say "2016 was the hottest year..."

The factoid that's been making the news in the last few days is an abbreviated brief summary of this press release: NASA, NOAA Data Show 2016 Warmest Year on Record Globally. Specifically, the GISS Model E temperature data product for 2016 enabled this statement: "NASA estimates 2016 was the warmest year with greater than 95 percent certainty."

That means we're pretty sure that this year (2016) was the hottest on record when compared to similar data compiled for all other years. This methodology can be used to compare data since 1880. When you compare within this range, the model has uncertainty and error bars. Here is one among many papers explaining the details. For example, Climate simulations for 1880–2003 with GISS modelE (2007) uses the data set to simulate climate during the range for which we also have actual measurements. This simulation includes simulation of the Model E global surface temperature anomaly. The simulation is then compared to actual data observed - so we can evaluate how accurately and precisely the model actually models climate within the range for which we have ground truth. Standard deviations are on the order of 0.2 degrees celsius, and observed average temperature rise is in the order of magnitude 0.6 degrees celsius, using this methodology - so we're in the ballpark of a three-sigma event.

Beyond 1880, extending into the distant past, we can use that same methodology - but we can't check the model against real data. Instead, we can back-project the simulation - run the model backwards! - to see what it would have predicted. The farther back we go, the greater the standard deviation - and the less confidence we can have. Think in terms of p-value: we only have a 95% confidence in the conclusion that 2016 is the warmest on record, using the data we actually have. With low confidence (!) we can make any statement we like! "With less than 5% confidence, 2016 is the warmest year in Earth's history." "With less than 5% confidence, I believe the elected leader of a major Earth government is being controlled by a shape-shifting lizard-alien." When we play linguistic games to report statistical information, we can make arbitrary statements that are absolutely factual and totally scientifically sound. Most scientists agree that a hypothesis rigorously tested to 95% confidence is "pretty solid," and most scientists agree that a hypothesis tested to less than 50% confidence is functionally worse than a "completely random guess." But hey - read any recent peer-reviewed published literature on machine learning to see how a research-community plagued by systematically-poor understanding of elementary statistics is encouraging smart humans to believe in methodologies that can only stand up to incredibly weak-confidence p-tests! State-of-the-art face recognition software can distinguish your face from a potato with near 95% confidence, which is good enough for many federally-funded law-enforcement surveillance programs! Heck, if you're ugly, a 15% performance rate is standard!

So now we have an impasse. To compare Year 2016 to paleoclimate, you need a paleoclimate model that can accurately estimate a historical GISS surface temperature at least as well as Model E. With what confidence can we actually reconstruct paleoclimate? To answer your original question, and to have a scientifically-meaningful confidence in the answer, we need a paleo-climate model whose accuracy and precision at estimating the GISS Model E temperature anomaly is better than, say, 0.2 degrees celsius (to give us that nice three-sigma event threshold). I do not know of any such paleoclimate model. This means that:

• It is very easy to find a scientist who confidently announces that 2016 is the hottest year on record (for the period 1880 to 2016)
• It is very difficult to find a scientist who confidently announces that same conclusion over a larger interval of years
• It may be impossible to find a scientist who can confidently announce the most recent year or period of years (with p-tests to 95%) during which Earth's climate was ever at this level. Our paleoclimate data sets are just not accurate enough to compare to modern GISS surface temperature accuracies; and the magnitude of the anomaly is not as large as our paleoclimate error bars.

So what do we do? Well, we share our data and our methods, and we try to make intelligent policy-decisions in the face of uncertainty. We must weigh risks.

It is my opinion that we (ecologically-minded scientists) are overly-fixated on temperature anomaly: and this is a poor strategy. People who disagree with the policies can then nitpick at the factual data; and temperature anomaly in particular has immense uncertainty. Instead, we should concentrate on something which is indisputable: pollution is bad. Let's reduce pollution! Let's reduce emissions! It doesn't even really matter if pollution causes warming, nor does it even matter how certain we are about that fact! The end-goal is to create a cleaner planet, and to reduce the ecological impact of industrial society.

...and quietly, while nobody is looking, we put better weather-cameras in space to help our next-generation researchers understand our planet with greater accuracy, resolution, and confidence.

Nimur (talk) 17:41, 23 January 2017 (UTC)

Thanks everyone for their input here. Count Iblis (talk) 02:04, 24 January 2017 (UTC)

Feynman Lectures. Lecture 44. Ch.44-5 ,Ch.44-5 Internal energy as function of something [3]

...

In doing a problem involving a given mass of some substance, the condition of the substance at any moment can be described by telling what its temperature is and what its volume is. If we know the temperature and volume of a substance, and that the pressure is some function of the temperature and volume, then we know the internal energy. One could say, “I do not want to do it that way. Tell me the temperature and the pressure, and I will tell you the volume. I can think of the volume as a function of temperature and pressure, and the internal energy as a function of temperature and pressure, and so on.”

— Feynman • Leighton • Sands, The Feynman Lectures on Physics, Volume I, Ch. 44-5

...

Now it is interesting that besides the pressure, which is a function of the temperature and the volume, and the internal energy, which is a function of temperature and volume, we have found another quantity which is a function of the condition, i.e., the entropy of the substance.

— Feynman • Leighton • Sands, The Feynman Lectures on Physics, Volume I, Ch. 44-6

In lecture 39 [4] Feynman says that

$pV={\tfrac {2}{3}}U$
$pV=NkT$
So U is a function of T only: $U={\tfrac {3}{2}}kT$. Where is my mistake? Username160611000000 (talk) 11:51, 21 January 2017 (UTC)

You're overlooking N. --Wrongfilter (talk) 12:51, 21 January 2017 (UTC)

Yes, thank you. $U={\tfrac {3}{2}}NkT$ and mean K.E. per atom is ${\tfrac {3}{2}}kT$. But this changes nothing, as N = const , and so U~T. Username160611000000 (talk) 13:10, 21 January 2017 (UTC)

In a closed system, T is just as constant as N. To see changes, you have to open up the system, e.g. put it in contact with a heat bath to change T, or combine two systems of the same size and temperature, thus doubling N. --Wrongfilter (talk) 14:02, 21 January 2017 (UTC)

We will not consider merging the two substances to keep N = const true. And at the moment of completing Lecture 44, we know only adiabatic expansion/compression and isothermal expansion/compression. Consider isothermal expansion. Feynman says there is no change in U (see Ch. 44-4 from start to eq. 44.4). Consider adiabatic compression: $T={\tfrac {const}{V^{\gamma -1}}}$ (see remark between eq. 44.5 and eq. 44.6). So during adiabatic compression we have $U=f(T)=f(g(V))$. But this changes nothing, U is still function of temperature (even if temperature itself is a function of volume). To be a function of two variables , the quantity must contain these two variables in one equation simultaneously, i.e. $U=f(T,V)$.Username160611000000 (talk) 14:51, 21 January 2017 (UTC)

As explained here:

The expression relating changes in internal energy to changes in temperature and volume is

$dU=C_{V}dT+\left[T\left({\frac {\partial p}{\partial T}}\right)_{V}-p\right]dV$

If you use the equation of state for the ideal gas, you find that U only depends on the temperature. Count Iblis (talk) 22:24, 21 January 2017 (UTC)

Do you mean that $T{\tfrac {\partial p}{\partial T}}=T{\tfrac {\partial }{\partial T}}({\tfrac {NkT}{V}})=T{\tfrac {Nk}{V}}{\tfrac {\partial }{\partial T}}(T)={\tfrac {NkT}{V}}=p$, and so $dU=C_{V}dT$? Username160611000000 (talk) 05:28, 22 January 2017 (UTC)

Yes, so you see that the term proportional to dV drops out, so the partial derivative of U w.r.t. V at constant T is zero. Or put differently, U as a function of V when keeping T constant, is constant. Count Iblis (talk) 07:55, 22 January 2017 (UTC)

Plastic food boxes, drink cans and bottles, use water wash then recycle

Recycle bins have signs say cannot put food and drink inside recycle bins, will spoil the things for recycle. How to know what plastic food boxes, drink bottles and cans safe for recycle? Must use water wash, but use more water is bad for earth, but recycle is more good for earth? Of course boxes that not touch the food or drink are not counted. --Curious Cat On Her Last Life (talk) 12:58, 21 January 2017 (UTC)

Contact your local recycling agency to find out what their rules are. They might have a website with the rules listed. ←Baseball Bugs ^{What's up, Doc?} carrots→ 13:14, 21 January 2017 (UTC)

Large amounts of the foods and drinks will cause problems, but small traces are inevitable and the recycling processes can handle them. The containers do not therefore have to be surgically clean (or even as clean as if you were going to re-use them intact), you do not therefore have to use large quantities of water for washing them. Drinks containers should be OK if they have merely been fully emptied: food containers can be adequately rinsed with, say, a quarter of their capacity's worth of water if not less, and if you do several at once you can re-use most of the water from container to container.

Incidentally, significant quantities of unconsumed food should also be disposed of in an appropriate manner, such as industrial-scale composting (which reaches sterilizing temperatures that home composting does not): my local council's refuse collection service includes bins dedicated to food waste for this purpose. {The poster formerly known as 87.81.230.195} 94.12.94.189 (talk) 13:55, 21 January 2017 (UTC)

See also Myth: You Must Rinse All Recyclables, Or Else! which says: "The real downside of dirty recyclables is that contaminated recycled material has less market value—which means the recycling service provider has less to spend on things like improving service and technology". Alansplodge (talk) 14:45, 21 January 2017 (UTC)

It will be cleaned and separated again and again anyway but at the begin it is usually just compacted without further processing and then traded. Ofcourse to get a good prize the initial collector tries to get the raw material as clean and preselected as he can. So it doesnt matter much if you throw in some boxes or bottles that are still half filled however if everyone would do that the first collector would have to clean and seperate instead of just compacting it to handy clusters and ofcourse he would also actually have to pay for the disposal of all the additional waste he ofcourse cant resell.

So you dont have to clean up your plastic waste befor you throw it into some recycling bin. Just make shure its as good as empty. --Kharon (talk) 00:02, 22 January 2017 (UTC)

Entering into the cost-benefit analysis of a recycling program is how much work you put on the individual customer, and how much work you put on the recycling agency. There's an inverse relationship between the amount of work you ask a customer to do and the amount of participation you get in a recyclable program. Where you require pre-sorted and pre-cleaned recyclables, the cost to the recycling provider goes down, but participation goes WAY down to; customers just throw all recyclables in with their waste, and you get very little participation. When you basically put no labor on the customer (what is often called "comingled recyclables"), that is they throw EVERYTHING recyclable, unsorted, into one big bin and don't have to do any work except remember which bin to put it in, you get MUCH better participation, but costs go up a LOT. So that weighs into the type of recycling program that an agency will set up. See here or here or here all of which cover various perspectives on recycling systems. --Jayron32 20:01, 23 January 2017 (UTC)

Convergent evolution in humans

In our artivcle Convergent evolution it says:

"When two species are similar in a particular character, evolution is defined as parallel if the ancestors were also similar, and convergent if they were not."

However, someone has recently added a well referenced paragraph that says:

"When humans migrated out of Africa, they moved to more northern latitudes with less intense sunlight. It was beneficial to them to reduce their skin pigmentation. It appears certain that there was some lightening of skin colour before European and Chinese lineages diverged, as there are some skin-lightening genetic differences that are common to both groups. However, after the lineages diverged and became genetically isolated, the skin of both groups lightened more, and that additional lightening was due to different genetic changes."

It would seem to me that the situation in humans equates to parallel evolution as the character was the same in the ancestor population, but that's clearly not the case. So how is convergent eveolution defind in a single species and can you have paralell evolution in a single species? Richerman (talk) 13:01, 21 January 2017 (UTC)

Evolution (of any sort) occurs in populations rather than species. Often, the two will effectively be the same, but in this instance the Chinese and European populations were sufficiently (though doubtless not entirely) separate that parallel evolutions (rather than a single evolution) can be considered to have occurred. This was not convergent, because although the net effect of skin lightening was much the same, it resulted from different mutations arising and being conserved, so technically different characters are involved, even though their gross visible effects are similar. {The poster formerly known as 87.81.230.195} 94.12.94.189 (talk) 13:38, 21 January 2017 (UTC)

That's a good point about evolution occuring in populations but the person that wrote the paragraph is a retired teacher of genetics and the reference he used is Association of the OCA2 Polymorphism His615Arg with Melanin Content in East Asian Populations: Further Evidence of Convergent Evolution of Skin Pigmentation, so it is obviously considered to be convergent. Richerman (talk) 13:48, 21 January 2017 (UTC)

Actually, thinking about it further, I would have described this instance as divergent evolution, since although the resulting appearance is roughly the same, there has actually been an increase in the genetic differences. I suppose it depends on whether your definitions are about gross appearance (which was the pre-genetic basis of anatomical comparisons) or actual genetic details. However, the editor in question and the authors of the paper are obviously qualified in this field whereas I'm only an enthusiastic fan, so I'm obviously wrong on that point. Maybe you should ping the editor and ask if the paragraph can be made clearer for us laypeople. {The poster formerly known as 87.81.230.195} 94.12.94.189 (talk) 14:14, 21 January 2017 (UTC)

I've discussed it a little on the talk page but not got very far yet. I was hoping for some further insights before I go back there. However, it's good to know I'm not the only one confused :-) Richerman (talk) 14:26, 21 January 2017 (UTC)

I think parallel evolution tends to be neglected. Sometimes you see "convergent or parallel". For one thing, if you don't know the exact history of the populations, it is hard to say with confidence that they had similar ancestors. Maybe one race became light-skinned first, and then the other, well, "converged" to that end point. The other argument, about how it is "really" divergent, is something that could be made in virtually every case. Convergent evolution at the molecular level is rare, though it does happen; I think red hair at MC1R is a repeated example. Nobody imagines that a fish and an ichthyosaur have more similar genes than the ancestors of the two did. Convergent is defined for a specific endpoint, and no other - the fins might converge, the bones of the skull not so much. Wnt (talk) 15:08, 21 January 2017 (UTC)

• It would be wrong to make too much of this. The distinction between parallel evolution and convergent evolution is not something that most geneticists pay a lot of attention to -- they tend to use the term "convergent evolution" for both. Even among scientists imprecision in terminology is pretty common. Looie496 (talk) 14:10, 23 January 2017 (UTC)

Medical apparatus

Does a medical apparatus exist for measuring the amount of human flatus pruduced and the number of flatal(?) events. I ask because medical web sites quote figures for quantity and number of daily emissions. --31.121.94.188 (talk) 18:59, 21 January 2017 (UTC)

• I have not looked at all of them, but there are quite a few medical papers in the references of Flatulence, one of which may contain information of the protocol. (Even then, such devices might not be commercially available, but that is a lead.) Tigraan^{Click here to contact me} 19:06, 21 January 2017 (UTC)

• I believe there is a rarely used device called a flatus bag/flatal bag, which was designed to collect samples. Analysis of the flatus gases could theoretically be useful in diagnosis of digestive system diseases, but other diagnosis techniques, such as a stool sample, seem to be easier to collect and more effective. StuRat (talk) 01:33, 22 January 2017 (UTC)

See "What is a rectal tube (or catheter)" illustrated, with discussion and "Use of flatus tube." Blooteuth (talk) 15:05, 22 January 2017 (UTC)

The contents of flatulence are commonly measured indirectly by blood sample. Only when there is a concern for a specific problem will a direct measurement be made. However, that is usually skipped over as an examination of the problem causing unusual flatulence may be easier to check than attempting to capture and analyze flatulence. I've only known two cases of a blood test for flatulence being performed in over 20 years. I've never known of a flatulence bag being used to capture flatulence, but I know it exists. First, I don't work in GI and most intestinal problems are checked using stool specimins, MRI, colonoscopy, or ultrasound. Flatulence is not a primary diagnosis tool. On a related note, I do remember a study on bovine flatulence that used flatulence bags. 209.149.113.5 (talk) 12:43, 23 January 2017 (UTC)

Flatus bag is a bluelink. DMacks (talk) 13:40, 23 January 2017 (UTC)

January 22

A diet rich in fruit and vegetables

Hi. I can find many sources asserting that it's advised to eat a diet rich in fruits and vegetables, but am not having luck finding any good sources that quantify exactly what that means. Loads of people eat "eat more" but how much is more? 30% of what you eat? 60%? 90%? Would appreciate any and all sources. 184.147.116.166 (talk) 23:54, 22 January 2017 (UTC)

You can look here to see if your present diet contains enough of the required vitamins, minerals, amino-acids and Omege-3 and Omega-6 fatty acids. But you need to build in safety margins, not everyone absorbs nutrients from foods as well, also some foods contain compunds that block absorption, e.g. oxalate in spinach will prevent your body from absorbing most of the calcium contained in it. You can deal with this by eating a wide variety of vegetables instead of depending on just a few to get some particular nutrients from. E.g. 100 grams of broccoli contains the following vitamins:

Vitamin A 1548IU 31% Retinol 0.0 mcg Retinol Activity Equivalent 77.0 mcg Alpha Carotene 0.0 mcg Beta Carotene 929mcg Beta Cryptoxanthin 0.0mcg Lycopene 0.0mcg Lutein+Zeaxanthin 1080mcg Vitamin C 64.9mg108% Vitamin D~ ~ Vitamin E (Alpha Tocopherol) 1.5mg7% Beta Tocopherol 0.0 mg Gamma Tocopherol 0.3 mg Delta Tocopherol 0.0 mg Vitamin K 141 mcg 176% Thiamin 0.1mg 4% Riboflavin 0.1 mg 7% Niacin 0.6 mg 3% Vitamin B 60.2 mg 10% Folate 108 mcg 27% Food Folate 108 mcg Folic Acid 0.0 mcg Dietary Folate Equivalents 108 mcg Vitamin B12 0.0 mcg 0% Pantothenic Acid 0.6 mg6% Choline 40.1mg Betaine 0.1mg

It contains the following amino-acids:

Tryptophan 34.0 mg Threonine 96.0 mg Isoleucine 92.0 mg Leucine 147 mg Lysine 155 mg Methionine 43.0 mg Cystine 31.0 mg Phenylalanine 116 mg Tyrosine 60.0 mg Valine 138 mg Arginine 200 mg Histidine 63.0 mg Alanine 114 mg Aspartic acid 329 mg Glutamic acid 549 mg Glycine 101 mg Proline 111 mg Serine 129 mg Hydroxyproline~

Minerals:

Calcium 40.0 mg 4% Iron 0.7 mg 4% Magnesium 21.0 mg 5% Phosphorus 67.0 mg 7% Potassium 293 mg 8% Sodium 41.0 mg 2% Zinc 0.5 mg 3% Copper 0.1 mg 3% Manganese 0.2 mg 10% Selenium 1.6 mcg 2% Fluoride 4.0 mcg

Omega-3 and Omega-6 fatty acids:

Total Omega-3 fatty acids 119 mg Total Omega-6 fatty acids 51.0 mg

Count Iblis (talk) 00:58, 23 January 2017 (UTC)

Thank you. Can you link directly to the page you are referring to at the nutritiondata site? I cannot find anything there re amounts of fruits and vegetables; it seems all about calories which is not my interest. 184.147.116.166 (talk) 17:58, 23 January 2017 (UTC)

You need to scroll down, you then see the additional details on vitamins and minerals, you can then click on "mode details" to get more precise data. Count Iblis (talk) 23:56, 23 January 2017 (UTC)

The 5 A Day page says the WHO recommend "a minimum of 400g of fruit and vegetables per day (excluding potatoes and other starchy tubers)." --TrogWoolley (talk) 13:56, 23 January 2017 (UTC)

Thank you. I think that number must come from this page, which interestingly does not say the total weight of food recommended, although it gives percentages for other types of food such as sugar. Perhaps the WHO feels that people who eat fewer calories need a higher percentage of fruit and vegetables than people who eat more calories? On the other hand, I do see some (not good sources) saying people generally eat 1500-2000 g of food per day. If true, that would make the 400 g recommendation a rather modest percentage. 184.147.116.166 (talk) 17:58, 23 January 2017 (UTC)

Yes, it's best to treat the 400 grams of fruits and vegetables as a minimum amount. I eat a lot more than average, about 4000 Kcal and I'll have at least 500 grams of vegetables, yesterday I had 800 grams of spinach that I ate with 1 kg of potatoes for dinner. I eat a lot of fruits, e.g. two bananas, 2 apples and some oranges during the day. Also note that nuts should be included in the diet, I eat 100 grams of walnuts every day. Count Iblis (talk) 02:51, 24 January 2017 (UTC)

January 23

syphilis among first peoples in south america, north america, and nearby islands, etc.

Do the descendants of first peoples exhibit more immunity and better tolerance to syphilis infections than most other people? I think if their bodies did fight syphilis better, it wold support the theory that the 1400s and 1500s european explorers brought it back from the americas after having sex with first peoples. But if so, where did the first peoples get it? Did their ancestors bring it over the bering strait 30000 years ago in a prior form that europe and asia previously had and may still have?Thanks144.35.45.33 (talk) 19:42, 23 January 2017 (UTC)

Wikipedia has an article titled History of syphilis. It would be a good starting place for your research. --Jayron32 19:54, 23 January 2017 (UTC)

Yes, I had already read that. It does not address my question.144.35.45.63 (talk) 16:07, 24 January 2017 (UTC)

The article states that there are two competing hypotheses, the Columbian and pre-Columbian. We do not know at present which is correct, so I'm afraid there's no answer to your question at present. --47.138.163.230 (talk) 01:00, 25 January 2017 (UTC)

Dehumidifier performance when the coils develop a coating of ice

When I read about why dehumidifier performance can deteriorate sources say that ice on the coils stops dehumidification and completely glosses over why this should be. Ice is at a cold temperature so water in the air should condense onto it just as it would onto metal. I don't see why this defrost period should be less effective than the usual cycle provided the fan continues to run (and it does). --78.148.97.148 (talk) 19:56, 23 January 2017 (UTC)

Ice blocks airflow between the coils, which reduces the amount of moisture in the air that has the chance to condense. Reduced airflow also slows the air moving past the coils, which leads to more ice buildup, which reduces airflow, which leads to more ice, which eventually blocks all airflow and system is not effective in any way. You can create this on your own (but I highly advise against it) if you have central air conditioning. Block at least half of the main air return duct. That reduces airflow to the main unit. The air moisture will begin freezing on the coils and, eventually, completely ice up the coils and block all air flow. Because the ice can cause severe damage to the unit, I strongly advise against going this, but if you really really really want to see it happen, it is possible. I did it inadvertently one summer by moving the trash can in front of the return duct while cleaning and it iced up the unit and cracked the coil, releasing all the coolant. Expensive mistake. 209.149.113.5 (talk) 20:09, 23 January 2017 (UTC)

• Dehumidifiers work because of the difference between absolute humidity (water content of the air) and relative humidity (current water content as a proportion of the maximum water content possible). Absolute humidity is constant, unless water is added or removed. The maximum humidity (the carrying capacity) though is temperature dependent and decreases with falling temperature. So if the air is cooled, the relative humidity does change: it increases, not because the water content has increased, but because the potential carrying capacity is less at reduced temperature. When the max humidity is reached, water condenses out.

This leads to the main problem with dehumidifiers: they don't work efficiently in cold weather. If the air is already cold, cooling it down further has only a small difference of carrying capacity to work with. They still work (if the temperature is still anything above the refrigerator temperature) but increasingly less efficiently: the electrical cost of running the refrigerator compressor is much the same, but the water yield is less. A well-designed dehumidifier should not become encased in ice; if it does, that may indicate that it is being operated at a low starting temperature.

Ice (so long it's dry, not wet) is also a good insulator. Refrigerator evaporator coils coated with it are no longer so effective. If they increase in size, they may also block airflow through them. This is less significant an effective than the humidity aspects, but it also makes a dehumidifier less effective in cold weather. Andy Dingley (talk) 00:09, 24 January 2017 (UTC)

January 24

Why doesn't bariatric surgery lead to starvation?

What causes the weight loss after bariatric surgery to be limited so that you don't keep on losing weight and starve to death? After all, your stomach has been made so small that you can't even tolerate the normal amount of food that most people need to eat. Count Iblis (talk) 02:03, 24 January 2017 (UTC)

You have to be prepared to follow a special diet, focusing on protein as you main source of calories, followed by vegetables that provide vitamins, and then carbs. Very small roux-en-y gastric surgeries which left a stomach the size of a lemon are less popular know, the gastric sleeve (which I had done on Friday) leaves you with a stomach the size of a banana. A woman I know who had the surgery did eventually die from kidney and liver failure due to malnutrition. Diet is key, and she ate fast food, and turned jaundiced as she starved to death.

You are expected to take vitamin supplements for the rest of your life, and your stomach will expand if you eat until fullness at each meal, which defeats the purpose of the surgery over the long run. Since I fasted on Thursday, I have not had to take any of my diabetes medicines. Eventually I should be off my blood pressure and cholesterol medicines, which will pay for the cost of surgery in under two years, and add 18 years to my life expectancy. (See the Northwest Mutal Life Expectancy Calculator.)

The big issue is keeping hydrated, since you have to drink about 64 oz of water and get 60 or so grams (more for men) of protein a day. So I have been drinking a quart of wonton soup broth and eating a quart of sugar-free jello made with a quart of protein-fortified water since then.

Basically, the bottom line is that this is not the sort of surgery you do without a lot of preparation, a long term commitment, and a support system where things like vitamin and protein supplements are available. I suggest you google bariatric diet at your favorite hospital's website, they will give reliable information.

μηδείς (talk) 03:59, 24 January 2017 (UTC)

Whole thing sounds like puppeteer birth control if you ask me. I still can't comprehend why, if people are willing to commit to this diet, they don't just go on it. I mean, either you commit to it or you don't? I don't follow the concept. Wnt (talk) 14:07, 24 January 2017 (UTC)

Is that an obscure Larry Niven reference, Wnt? Even if it is, I don't understand it, and either way it sounds potentially offensive, so perhaps you'd like to clarify? {The poster formerly known as 87.81.230.195}94.12.94.189 (talk) 15:32, 24 January 2017 (UTC)

Pierson's Puppeteers forbade contraception; the only allowable form was surgery. Hence, a trillion puppeteers. Anyway, bariatric surgery a last-ditch possibility for people who have tried everything else. --jpgordon^{𝄢𝄆 𝄐𝄇} 16:37, 24 January 2017 (UTC)

Puppeteer birth control if you like, but: (1) It is considered a last ditch option for the morbidly obese with co-morbidities such as diabetes type II; my body mass index is/was 35, (20 is normal) and I was diagnosed with type II diabetes in 2012. (2) You are expected to have dieted, which I have done lifelong, as well as at one point 1hr/ day on the stairmaster and rowing machine, yet was still 40 lbs over weight. (3) The surgery is a tool. At this point I am full with two ounces, eventually I will be able to eat a lb of food a day, with three full meals of 4 ounces and two 2 ounce snacks (a slice of peperoni bread is 2 ounces).

And (4), most importantly, the portion of the stomach removed includes the portion which produces ghrelin. Hence the gastric sleeve is actually a type of endocrine surgery; you're not just shrinking the bag, your removing a malfunctioning part of your endocrine system. One of the most intriguing consequences of the surgery is that patients’ blood sugar levels normalize within days—long before any weight loss has occurred. Patients can often stop taking their diabetes medication even before leaving the hospital.

I had the surgery at 2pm Friday, was home Saturday afternoon, am eating broth and jello, and can start yoghurt, cream soups, farina, scrambled eggs, and so forth tomorrow, most regular foods in two weeks. I don't feel deprived; I feel liberated.

μηδείς (talk) 18:08, 24 January 2017 (UTC)

Best wishes for an excellent outcome, Medeis! --Trovatore (talk) 22:05, 24 January 2017 (UTC)

Thanks, Trovatore. So far it has been miraculous, and a walk through the park. (Of course I have been through 7 major surgeries, and this was my second time on a morphine drip, so I knew what to expect.) But except for taking (needing) dilaudid for abdominal pain when I lay down to sleep, I am fully functional. Even went to the library and grocery shopping today. μηδείς (talk) 23:35, 24 January 2017 (UTC)

Brothers and sisters in dog packs

I cannot find this at Dog behavior.

In a (wild) dog pack, do brothers and sisters have babies together? Anna Frodesiak (talk) 02:55, 24 January 2017 (UTC)

I've been trying to find good information on this by searching "Dhole" (Indian wild dog) social structure, and "African wild dog" (Also called "Cape Hunting Dog") social structure, but have run out of time. You could follow these leads. They have both been studied extensively. 49.197.122.249 (talk) 08:42, 24 January 2017 (UTC)

Depending on what is meant by "wild dog", there are several different canines that could be so described. Wild canis lupus are generally called wolves, which would be the wild relative to the domestic dog. There are also feral dogs, which are different, as well other species of canine also called "wild dogs", such as the African wild dog or Lycaon pictus. This article from 2012, seems to indicate "no" for Lycaon pictus. --Jayron32 14:22, 24 January 2017 (UTC)

This study suggests "rarely". --jpgordon^{𝄢𝄆 𝄐𝄇} 16:30, 24 January 2017 (UTC)

Thank you all. Anna Frodesiak (talk) 19:52, 24 January 2017 (UTC)

milk tooth

Which of the non-human mammals have elementary teeth,once those teeth fall and again new teeth replace.--Akbarmohammadzade (talk) 04:18, 24 January 2017 (UTC) Milk tooth

Our article Diphyodont which is linked to from milk tooth mentions a small number but also makes it clear it applies to most mammals. So an exhaustive list is unlikely. In terms of mammals, it's probably more useful to ask which ones aren't diphyodont. Polyphyodont lists some. Monophyodont may lists others but it seems we don't even have an article, perhaps because it's relatively rare. Nil Einne (talk) 05:41, 24 January 2017 (UTC)

One of the most important themes of mammal evolution has been the development of a mechanism allowing us to both bite and chew with precision. Birds and reptiles bite, but they do not chew. The alligator's teeth are simple alternating pegs made for grabbing and tearing. Mammalian teeth line up in a set pattern that developed as mammals evolved from therapsids. The incisors nip, the canines grab, the premolars (also carnassials) tear and the molars crush and chew.

Their proper function requires proper alignment, and a system where new teeth just come out whenever an old one is lost has been replaced by one of the proper characters of mammals; the one-time replacement of milk teeth by adult teeth in an orderly fashion. Of course there are variations that have developed on this theme, but it was the primitive condition of the first mammals, and still continues in most mammalian groups. μηδείς (talk) 23:47, 24 January 2017 (UTC)

Have you seen someone at the age of 90 grow teeth in his mouth again

--Akbarmohammadzade (talk) 04:26, 24 January 2017 (UTC) what is old age growing tooth ? — Preceding unsigned comment added by Akbarmohammadzade (talk • contribs) 06:44, 24 January 2017 (UTC)

Many years ago, there was a buzz on the Internet about a Russian woman who grew a tooth again long after she had lost all her teeth. Then, it turned out to be squamous cell carcinoma. That news wasn't as popular, so I figure anyone who read the first story still remembers the old Russian lady who regrew her teeth (though she only grew one "tooth"). 209.149.113.5 (talk) 13:05, 24 January 2017 (UTC)

The condition of growing extra, or "supernumary", teeth, is called Hyperdontia. --Jayron32 14:04, 24 January 2017 (UTC)

As in movies

In movies, the person is shown to be made again just by a thread of hair. And, the memories are shown to be implanted. Is it even possible to implant the memories? And, how possible is the new clone be the same age from whom the clones were prepared? Are those things theoretically possible ? Learnerktm 07:39, 24 January 2017 (UTC)

• Not such which movie this refers to, though it could be The Fifth Element.

The genetic "code" is stored in a DNA molecule that is (mostly) the same in all cells for a given organism, including hair follicles, so it is theoretically possible to make a clone from a single follicule (though not from the external hair part). Technically, of course, that is another story; you would need to have a full genome sequencing technique that works with a single cell, and then still generate an zygote with the matching genome, both of which are as far as I remember not feasible today. As for the new clone being the same age, well, if you wait enough time...

Notice however that DNA is not the full source code, and the individual's development is affected by the environment, so the end result should be "close enough", not "fully indistinguishable".

I will leave the memory question to someone else, but you can start at encoding (memory). Tigraan^{Click here to contact me} 09:13, 24 January 2017 (UTC)

You wouldn't need full sequencing. You could extract the follicle cells, turn them into iPS cells (this is actually done in the building I work in), and theoretically form a clone out of those. The last bit is very theoretical in humans. (BTW, single cell sequencing is very much possible). And no, you can't implant memories, as we basically still know very little about how they work. Fgf10 (talk)

Cloning an individual is certainly possible (the main barriers are political/ethical/etc.), but bear in mind identical twins are clones. They have some similarities but many differences. To transfer memory, you really have to lay on some industrial strength pseudo-science, preferably making up something original as you go along. Perhaps the memory is somehow "transferred to the morphogenetic field" and begins to flow back again, or identical twins have a kind of telepathy that occasionally occurs, and in people without twins the excreted thoughts float around in the ether for years before winging back to the new clone. Or there are billions of tiny, impossibly advanced aliens embedded in every pebble and drop of snot that make a secret high-resolution data store that they mistakenly put back into the clone. I dunno, think of something. But it's not going to be anything remotely plausible for ordinary people in a world where one lousy stroke reduces a loved one to living dead status for years on end. Wnt (talk) 14:02, 24 January 2017 (UTC)

An important article about what information is missing when you clone is epigenetics. Vespine (talk) 23:39, 24 January 2017 (UTC)

(I just realized Tigraan already linked to that article). Vespine (talk) 23:41, 24 January 2017 (UTC)

Octane rating

I know that branched and cyclic hydrocarbons almost always have a higher octane rating than straight-chain ones, but what exactly is the mechanism which determines this? Does this have something to do with Markovnikov's rule and the relative energies for the formation of free radicals, i.e. that during ignition, the molecules break up more gradually and/or in a more predictable manner? 2601:646:8E01:7E0B:80A2:2428:A67E:94FC (talk) 11:47, 24 January 2017 (UTC)

Combustion chemistry is complex. The octane rating is not even a physical property, but an empirical measurement. But I think that you're on the right track looking at radical mechanisms. Certainly radicals have a key role in combustion: tetraethyllead served essentially to place lead atoms into the reaction, which would interact with the free radicals. Since a free radical with a branch point is expected to be more stable than one that does not, that may matter. But the length of straight chains also matters greatly even when there is no variation in how many carbons each carbon bonds to - compare the -130 for hexadecane to the 112 for propane! And any branched structure inevitably shortens the straight chain and reduces the size of the molecule compared to others with a similar number of carbons. Wnt (talk) 14:34, 24 January 2017 (UTC)

Autoignition temperature is probably one of the relevant parameters, an article that is sparse on the chemical/structural causes but does mention chain-branching as being a consideration. And that aricle does go into some mathematical detail about the timing (using parameters of thermal conductivity, density, and specific heat capacity), which is clearly important in the octane-rating idea. DMacks (talk) 15:17, 24 January 2017 (UTC)

@Wnt:, some of the chemistry is covered by Combustion#Reaction mechanism. Should that section be offloaded to Combustion chemistry or should that redlink redirect to that section so at least the link turns blue? DMacks (talk) 15:24, 24 January 2017 (UTC)

That's a tolerable redirect for now. I don't want to put the mechanism of combustion under combustion chemistry, because I think properly the latter term refers to the field of study rather than the process itself. I'm sure there must be many academic departments and private corporate institutes which deserve to be mentioned in such an article, for example, though I know truly very little about it. Wnt (talk) 16:57, 24 January 2017 (UTC)

Ratings for lamp shades based on heat or light output?

I keep seeing shades with ratings on for the lights used in power/watts but they give different ratings for incandescents and energy-saving forms which to me makes no sense. If the lamp shade can handle 42 watts of halogen, why not 42 watts of any other bulb type? — Preceding unsigned comment added by 129.215.47.59 (talk) 15:30, 24 January 2017 (UTC)

This article is about lamp shade design, and shows recommendations based on Underwriters Laboratory standards; it appears the standards are based on incandescent bulb wattage, and designed to account for ventilation and heat output. I have no idea if similar standards have been developed for wattage of other bulb types (CFL, LED, etc.) but I would not expect the heat/wattage relationship to be the same given different types of bulbs. That is a CFL which actually draws 60 watts may not have the same heat properties as an incandescent bulb would. --Jayron32 15:53, 24 January 2017 (UTC)

[Edit Conflict] Because the important factor here is the heat the bulb puts out (which may cause the light shade or the fitting to catch fire if the shade's rating is exceeded). For example, traditional incandescent bulbs put out the majority of their rated power as heat (typically 95–98%); the various energy-saving types of bulb put out much less of their output as heat – which is why they're energy saving; most of their energy is being output as visible light, so they actually consume much less power for the same level of illumination. For example, a rather dated 20W compact fluorescent bulb is claimed on the packaging (which I still have to hand) to put out the same light as an 85W incandescent (were such a thing to exist).

Different types of 'bulb' give different proportions of their total power output as heat – LEDs, for example, give off almost no heat – so it's important to pay regard to the ratings to avoid putting too much heat into the shade, and as explained. {The poster formerly known as 87.81.230.195} 94.12.94.189 (talk) 16:01, 24 January 2017 (UTC)

{{ec}} The wattage of the bulb is the total amount of energy it consumes, energy that is converted into light and heat. Different types of lighting have different relative levels of light vs heat produced--"efficiency" talks about how much energy is wasted as heat in the process of creating a certain amount of light. A major difference among incadescent to CFL to LED is the increase in efficiency, meaning it takes a lower wattage bulb to produce the same amount of light, and therefore less heat is produced. Or the same wattage produces more light and less heat. I have no idea what criteria are used to establish the ratings on this item, but "total energy" only relates to the wiring, not the effects of the different fates of that energy. DMacks (talk) 16:03, 24 January 2017 (UTC)

The specific example is (a) "42W Eco Halogen" vs (b) "12W Low Energy". Both are equivalent lighting (42W eco halogen and 12W low energy/CFL are both 60W incandescent). So the rating is actually a limit on brightness? The halogen uses more energy to get the same brightness, which means more heat produced. If the design limit were about heat, I should be able to put an even higher wattage bulb in if it's of a more efficient bulb-type. DMacks (talk) 16:14, 24 January 2017 (UTC)

It was common to limit the wattage to 60 watts for incandescent bulbs in such fittings for heat reasons. I've often seen heat damage to fittings as a result of ignoring the limit. Are the manufacturers just confused? I can see no reason to limit the brightness. Dbfirs 19:37, 24 January 2017 (UTC)

Food waste and rat traps

Given that every restaurant and supermarket will generate some food waste and that rats are ubiquitous in cities, why don't humans look for free food in dumpsters, thereby competing with the rats and seagulls and other urban creatures for food that costs time and energy instead of coins and paper? Why must the food be shipped from a factory or a farm and transacted in grocery stores? Why can't humans just eat what they can find locally? Other animals spend their entire days searching for food. Humans have to work 8 hours a day (full-time) or less than that (part-time), and 8 hours may be spent on sleeping, so the remaining 8 hours may be spent on searching for food in dumpsters and setting up rat traps or teaching other humans how to search for food to minimize food wastage. If a seagull ingests toxins, then the human that eats the seagull ingests toxins as well. The toxins will limit human population growth, so in order to expand the human species, humans will have to learn how to minimize the presence of toxins in the environment. 66.213.29.17 (talk) 16:09, 24 January 2017 (UTC)

You first. And humans do look for free food in dumpsters. --jpgordon^{𝄢𝄆 𝄐𝄇} 16:15, 24 January 2017 (UTC)

Don't know what planet your living on but many folks have had to resort to Freeganism & Dumpster diving for many years in order to to survive and not let their children starve to the point that they are taken away by the social services. Many people fall through the cracks of social welfare and so are all ready competing with rodents.--Aspro (talk) 16:27, 24 January 2017 (UTC)

I didn't know there was an article on Freeganism! Though, I didn't know that was an actual concept. 66.213.29.17 (talk) 16:48, 24 January 2017 (UTC)

I think this suggestion is too stupid to warrant further discussion. 129.215.47.59 (talk) 16:29, 24 January 2017 (UTC)

That is your opinion. This modern developed World is the richest in all recorded history but hunger has not gone away and is getting worse. Just be thankful that you have never experienced what prolonged hunger really feels like! Remember, haggis was hailed because it gave subsidence at the time of the year when animal protein was in very short supply... and it was so cheap that even Scottish peasants could afford it, as it was made from the discarded offal.--Aspro (talk) 16:40, 24 January 2017 (UTC)

Obviously it's my opinion. The OP suggested that people voluntarily eat foot with toxins as an alternative to purchasing food of an appropriate quality in a supermarket. They suggested that people voluntarily off themselves by scavanaging and foraging and hunting pigeons when they're not busy at work. It's moronic but I'm not sure there's any objective way to frame that. But go ahead and waste your time on what looks like a troll post. — Preceding unsigned comment added by 78.148.97.148 (talk) 20:13, 24 January 2017 (UTC)

Lobster#History is interesting. Never know what will become popular. DMacks (talk) 16:51, 24 January 2017 (UTC)

The potential for disease seems obvious. Scavengers are typically specialized for the purpose. That said, the "omnivorous" human is quite a mystery to me. I've been told Homo erectus gained an endurance runner's physique doing marathons following the vultures above old lion and hyena kills with bones to crack for their marrow. But people do not do so well eating rotten food as to seem like plausible scavengers; their primate stomachs and lack of vitamin C biosynthesis for example are in line with fruit eaters. Though humans can be carnivorous, they are not true carnivores either in that they don't (usually) eat feces; they hack off just certain bits they like. I am inclined just to take the approximation that humans don't properly scavenge because they're not scavengers. Wnt (talk) 17:04, 24 January 2017 (UTC)

By coincidence, just 2 days ago I went to put a bag of garbage into a skip (dumpster). The one I usually use was locked, so I went to the next one which is owned by the nearby supermarket. There, sitting on the top were 2 salmon fillets in totally perfectly sealed packaging. So, what do I do? Yes, I took them. The fillets were dumped because they were on the last day of their "sell by" date. I was thinking more that animals had been reared and died to provide this food...what an immoral act to throw them out simply for commercial reasons. DrChrissy ^(talk) 20:38, 24 January 2017 (UTC)

material science

if a unit cell of a tin has a tetralgonal symentry with a and c lattice parameters 0.318nm and 0.583nm respectively, if it density, atomic wieght and radius are 7.30g/cm, 118g/mol and 0.15nm respectively. What is its atomic packing factor.

Its atomic packing factor is...a good homework question indeed!

Please do your own homework.

Welcome to the Wikipedia Reference Desk. Your question appears to be a homework question. I apologize if this is a misinterpretation, but it is our aim here not to do people's homework for them, but to merely aid them in doing it themselves. Letting someone else do your homework does not help you learn nearly as much as doing it yourself. Please attempt to solve the problem or answer the question yourself first. If you need help with a specific part of your homework, feel free to tell us where you are stuck and ask for help. If you need help grasping the concept of a problem, by all means let us know.

DMacks (talk) 16:34, 24 January 2017 (UTC)

Genetic modification

If an apple is genetically modified to contain caffeine or some kind of drug from another plant, then would it get a food label or a drug label? How would doctors prescribe such a medicine? Can pharmaceutical companies own large industrial farms with genetically modified apples, eggplants, squashes, romaine lettuce heads, etc.? 66.213.29.17 (talk) 17:21, 24 January 2017 (UTC)

Here is an article that discusses some of the issues surrounding the use of genetically modified organisms and drugs. Here is perhaps a more neutral source that discusses the legality. One thing to note: regulation has always lagged behind technology. That is, governments don't create laws in anticipation of a concept maybe existing sometime in the future. Governments only create regulation to deal with problems as they come up. Since there currently is no genetically modified apple that has caffeine, there exists no law that deals with the way such a thing is to be labeled, and who is responsible for regulating such a thing. Unless and until caffeinated apples exist, your question will continue to be unanswerable. --Jayron32 17:28, 24 January 2017 (UTC)

That said, I doubt there is tremendous interest in genetically engineering drug containing apples. Apples require large areas of land, nutrients, water, etc., to successfully grow. It's the only way to get an apple, but it isn't the only way to get most drug compounds. If drug compounds are made from genetic engineering at all, bacteria are usually used. They make excellent chemical factories and are used in bioreactors, where much more efficient use of input materials is made to get the desired product. Insulin is made in e. Coli bioreactors, for example. --OuroborosCobra (talk) 19:49, 24 January 2017 (UTC)

Does the SI need 7 basic units?

Besides the glitch of the kg (which is not defined in natural units), couldn't the SI be simplified? Couldn't we define it in less than the 7 SI base units - second, metre, kilogram, ampere, kelvin, mole, and candela? The meter for example, is just a fraction of the distance that light travels in 1 second, therefore, not fundamental, but derived. Or, are they trying to define all units based in concepts that are common knowledge? Hofhof (talk) 18:17, 24 January 2017 (UTC)

The base SI units are based upon basic measurements. The fundamental set of base measurements is somewhat arbitrary, but at some point you need to have certain measurements pegged to universal standards, such measurements then are irreducible to other measurements. You need to measure distance, time, number and mass, and also have some fundamental measurement of electricity, heat, and light. The first four are more "fundamental" in a sense, since distance doesn't give you a lot of choices: the space between two points is the space between two points, and not much else to measure there. The number of objects in a set is a countable thing, and you pick some number (Avogadro's number in this case) as the defined counting set. So those measurements are pretty much locked in. For measurements of electricity, heat, and light, there's some leeway how you define the fundamental measurements. For example, is electric charge more fundamental or is electric current more fundamental? Arguments could be made either way, and it doesn't matter much since you can define one in terms of the other and time (thus current = charge divided by time, OR charge = current times time). For various reasons, it was decided "current" would be chosen as the base measurement, and then charge was pegged to that. The same with heat measurements for example: do we go with energy or temperature, knowing the two are tied together by the Boltzmann constant? It was decided to go with Temperature instead. Once you've defined your basic set of measurements, then you pick a unit that is most convenient for the work you are doing. For most human-sized things, meter, kilograms, seconds, moles, amperes, kelvin, candela, etc. all work well because for most people, it gives them nice 1-3 digit numbers to work with. People's number sense tends to break down for very large or very small numbers, so the units chosen allow numbers that we can wrap our heads around. --Jayron32 18:28, 24 January 2017 (UTC)

Convenience is why inches, feet, yards, etc. still work well. ←Baseball Bugs ^{What's up, Doc?} carrots→ 23:40, 24 January 2017 (UTC)

Yes, it is quite possible. CGS uses just three. Ruslik_Zero 20:46, 24 January 2017 (UTC)

Animals making knots

I just added Knot#Use by animals and am wondering if other animals make and use knots. Birds? Primates? Anna Frodesiak (talk) 22:33, 24 January 2017 (UTC)

Hi Anna - some of the most wonderful knots are produced by weaver birds.

Weavers and nests in western India

But is a weave a knot? We've not figured that out yet. Anna Frodesiak (talk) 22:41, 24 January 2017 (UTC)

I asked myself the same question before I posted here. So, I checked our Knot article which states "A knot is a method of fastening or securing linear material such as rope by tying or interweaving." So there we have it - WP is never wrong (hee hee)! DrChrissy ^(talk) 23:10, 24 January 2017 (UTC)

Having thought about this a little more, if we accept the "looser" definition of knots as including inter-weaving, many bird nests could be included as having knots and many other animal nests such as drays of squirrels and nests of primates (they interweave leaves together) could be included. Perhaps I am getting myself into knots about this! DrChrissy ^(talk) 23:20, 24 January 2017 (UTC)

Orangutan - http://www.livescience.com/54780-orangutan-wattana-is-knot-tying-master.html Wymspen (talk) 23:30, 24 January 2017 (UTC)

That is a great video - thanks for that! I have a word of caution though. The authors state that they never taught the orang to tie knots. This might be true, but that does not mean she did not learn by Observational learning. However, the video clearly shows her tying knots! DrChrissy ^(talk) 23:47, 24 January 2017 (UTC)

Hagfish make knots to pull scraps off dead bodies or escape being caught. Dmcq (talk) 23:52, 24 January 2017 (UTC)

How much do minor planet spacecraft change their targets' orbits?

Has one changed a minor planet orbit by a millimeter or changed it's year enough to make it a millimeter late or early by 2100? What about a meter? A kilometer? More?

Yes I am aware that radiation pressure and comet outgassing might change their orbits many orders of magnitude more than a millimeter. Sagittarian Milky Way (talk) 00:15, 25 January 2017 (UTC)

A millimeter? Maybe, but how would we know? You'd need to deploy precision instruments like laser rangefinders to detect that tiny a difference; I don't think any existing craft have them. I'm pretty sure anything larger than that is safely out of the question. Gravity tractor gives a worked example of using a spacecraft to alter the orbit of an asteroid over 10 years. Compare the mass of a spacecraft like Dawn. --47.138.163.230 (talk) 01:10, 25 January 2017 (UTC)