Like anti anxiety pills, anti depressants. I've read lots of people say it does nothing. I used quite a number of anti depressants and all I feel is sleepy. I also used phenibut and it does NOTHING. I feel like they are all scam by greedy pharmaceutical companies. Has there been any investigation into the effectiveness of mind altering medicine? If you know any articles please link. Thanks. [[User:Money is tight|Money is tight]] ([[User talk:Money is tight|talk]]) 07:59, 22 March 2017 (UTC)
Revision as of 07:59, 22 March 2017
Welcome to the science section of the Wikipedia reference desk.
The best answers address the question directly, and back up facts with wikilinks and links to sources. Do not edit others' comments and do not give any medical or legal advice.
This site[1] says the water hardness for Vancouver, WA is 60 to 160 ppm. Looking that up in Hard_water#Hard.2Fsoft_classification show that 60 ppm is soft, while 160 ppm is considered hard.
1. Is it normal for water hardness to vary over such a wide range?
Note these are highest and lowest values recorded which would not necessarily correspond to "normal variation." It's common for hardness levels vary substantially, for example due to seasonal and interannual fluctuations of precipitation, source from which the water is drawn, etc. See e.g. [2]Shock Brigade Harvester Boris (talk) 02:11, 18 March 2017 (UTC)[reply]
This says the readings are from 60-130 - a little closer together, but not much. If you examine the other tests, you see even larger variations than the 100% for hardness. I initially assumed there were multiple sources, but this says they're all from aquifers. Of course, each aquifer may be slightly different and there are apparently 40 separate wells being tapped. As far as whether it's normal or not, the same kind of report on my local water supply is not broken down in quite the same way, but there are values that also more than double in scale. Matt Deres (talk) 02:42, 18 March 2017 (UTC)[reply]
The cause is the presence of soluble minerals, especially calcite in the aquifer rock itself (not really soil). In southern England for example Chalk Group aquifers deliver the typically hard water generally encountered there, although the sandstones of the Lower Greensand Group aquifers [3] deliver softer water. Mikenorton (talk) 12:12, 18 March 2017 (UTC)[reply]
Can electrical current change a chemical bond from covalent to ionic?
I swear this is not homework. I am not a chemistry student. I just want to have a little sharper understanding of atoms and not sure I understand this right:
This is a tough one - I don't claim to know a good case. Obviously many ions will tend to react immediately - put H+ and OH- together and they turn into water again. An electric current is applied over a distance, so even if it coaxes the two apart, they will only find new partners in either direction. The best guess that I could think of in five minutes is ammonium hydroxide - in dilute aqueous solution, it is a combination of NH4+ and OH-; yet supposedly there is an "ammonium hydroxide gas" that seems most famously used in pink slime manufacturing, which if true should be an actual covalent molecule of NH4OH since ionic bonds don't tend to work in the gas state. That makes me wonder if you could come up with some nonpolar solvent where NH4OH stays covalent, but you could coax it apart for some duration with strong current. I have absolutely no idea if you can do this, but I've seen weirder chemistry. Wnt (talk) 23:19, 18 March 2017 (UTC)[reply]
"ionic bonds don't tend to work in the gas state" is a pretty broad claim. Sure, you lose the solvation that provides an alternative bonding to the ion-pairs, but that doesn't mean the alternative is that they actually share electrons rather than just electrostatically attract each other. Compare to doi:10.1063/1.3483897 and doi:10.1063/1.471520 as some lead refs determining NaCl and other classical ionic salts behave as ionic species in the gas phase. Even the nature of ammonia in water is not as clear-cut as "a combination of NH4+ and OH-". See for example doi:10.1364/JOSA.68.000429 that makes the case for more "NH3 hydrogen-bonded to water" in contrast to other ammonium salts that actually have NH4+ cations. DMacks (talk) 16:22, 19 March 2017 (UTC)[reply]
@DMacks: The first paper does indeed give the impression that gas phase NaCl has an entirely ionic character, with no covalent aspect to it at all. Thus their ring dimers, trimers and tetramers have mathematically polygonal angles - 90 or 120 or 135 degree angles. However... it's a simulation, and I wonder if that is truly accurate. Yet they clearly expect the opposite of what I did, and that would be a clue - thanks. But ... why aren't molecular orbitals even relevant here? Why don't they form some sp-like thing at all? And ... well, I was thinking that if covalent and ionic species could coexist in gas phase, you could excite one to the other, which would fulfill the OP's request. Wnt (talk) 13:21, 21 March 2017 (UTC)[reply]
A covalent network solid under an applied voltage can behave as a metal (e.g. graphite), as a semiconductor (e.g. diamond or silicon) or as a dielectric (e.g. silicon dioxide) -- depending on the band structure and, to a varying extent, on the presence of impurities (dopants). Applying electric current to a covalent network solid per se doesn't change the bond type. However, if the current is strong enough to cause a phase transition (by increasing the temperature and/or pressure) then all bets are off. Also, as mentioned above, a strong enough current will ionize some of the material, but that's not ionic bonding - just ions (plasma) Dr Dima (talk) 08:58, 19 March 2017 (UTC)[reply]
Instead of electricity, high pressure can do it, eg see[1]. Also sodium under pressure can change from metallic bond to ionic and become an insulator. Nitrogen pentafluoride is predicted to be ionic under pressure, but would only exist as a mixture with covalent bonds at ambient conditions. Electric current flow in itself is unlikely to change bonds, as only very few bonds will be experiencing electron movement at anyone time. Perhaps a high magnetic field may make some kind of difference, but I don't know any examples. Graeme Bartlett (talk) 01:41, 20 March 2017 (UTC)[reply]
Thanks. Because electronic was started in the second part of XX century (in 1950 years), it gives me think that photoelectric effect been explored at first in electrotechnic (radiotechnic) which was started in the end of XIX century. These all gives me think that semiconductory effect did been explored at first in electrotechnic (radiotechnic). Is I’m right?--79.139.157.152 (talk) 16:35, 18 March 2017 (UTC)[reply]
"Did been"? Yes, this is highly typical of our site-banned friend. And there is no grammatical construction in actual Russian that would lead to this pseudo-construction. μηδείς (talk) 22:53, 18 March 2017 (UTC)[reply]
Organic chemist needed
I discovered Oxalate degrading enzyme in the speedy-deletion queues (someone had misidentified it as spam) a couple of days ago, since which time it's been significantly reworked — but not in fluent English, and the author clearly isn't familiar with our formatting or layout conventions. I've cleaned up the language and wikified it, but I'm not sure I've done the best. Here's how it looked ten minutes ago:
Extended content
Oxalate degrading enzymes
Oxalate degrading enzyme, is a catalytic degradation of oxalic acid polymer protein, including oxalic acid oxidase, oxalic acid decarboxylase and formyl-CoA decarboxylase.
1. Brief introduction
2. Classify
3. Calcium oxalate stones and oxalate degrading enzymes
Brief introduction
Enzymes are macromolecules with biocatalytic activity, and most enzymes are proteins. Almost all of the cellular processes in the body require enzyme involvement to improve efficiency. Oxalate degrading enzyme, is a catalytic degradation of oxalic acid polymer protein, including oxalic acid oxidase, oxalic acid decarboxylase and formyl-CoA decarboxylase.[1]
Classify
Enzymes that currently degrade oxalic acid in the biology include oxalate oxidase, oxalate decarboxylase and formyl-CoA decarboxylase.[2]
Oxalic acid oxidase（EC1.2.3.4）mainly in plants, it can degrade oxalic acid into carbon dioxide and hydrogen peroxide.
Oxalate decarboxylase ( Oxalate decarboxylase，OXDC，EC4.1.1.2) is a kind of oxalate degrading enzyme containing Mn2+, mainly in fungi or some bacteria, it can be in the absence of other cofactors under the action of the degradation of oxalic acid directly to form formic acid and CO2.[1]
Formyl-CoA decarboxylase（EC4.1.1.8）mainly mediated degradation of bacterial oxalic acid.[2]
Calcium oxalate stones and oxalate degrading enzymes
Calcium oxalate is the main component of urinary calculi, one of the important reason for leading to calcium oxalate stone disease is for the lack of degradation of oxalic acid metabolic pathway. Therefore, the use of oxalate degrading enzyme for degradation of oxalic acid in the human body has become an important research direction for the prevention and treatment of calcium oxalate stone disease.[2]
Studies have shown that with the intake of a large number of foods rich in oxalic acid, the excretion urinary acid in the urine will be significantly increased. Therefore, to reduce the intake of exogenous oxalic acid can reduce urinary oxalate excretion, can significantly reduce the recurrence of stones.[3]
Reference materials
1. Properties and Application of Oxalate Decarboxylase Wikipedia [citation date 2016-12-14]
2. Research progress of oxalate - degrading enzyme in the prevention and treatment of calcium oxalate. Wikipedia article [citation date 2016-12-14]
3. The Latest Development of Preventive Treatment of Calcium Oxalate Calculus. Wikipedia article [citation date 2016-12-14]
And here's what it looks like now:
Extended content
An oxalate degrading enzyme is a catalytic degradation of oxalic acid polymer protein, including oxalic acid oxidase, oxalic acid decarboxylase and formyl-CoA decarboxylase.
==Brief introduction==
Enzymes are macromolecules with biocatalytic activity, and most enzymes are proteins. Almost all of the cellular processes in the body require enzyme involvement to improve their efficiency. An oxalate degrading enzyme is a catalytic degradation of oxalic acid polymer protein, including oxalic acid oxidase, oxalic acid decarboxylase and formyl-CoA decarboxylase.[1]
Oxalic acid oxidase（EC1.2.3.4）occurs mainly in plants. It can degrade oxalic acid into carbon dioxide and hydrogen peroxide.
Oxalate decarboxylase (Oxalate decarboxylase，OXDC，EC4.1.1.2) is a kind of oxalate degrading enzyme containing Mn2+, mainly in fungi or some bacteria. It can appear in the absence of other cofactors under the action of the degradation of oxalic acid directly to form formic acid and CO2.[1]
Formyl-CoA decarboxylase（EC4.1.1.8）mainly mediates degradation of bacterial oxalic acid.[2]
==Calcium oxalate stones and oxalate degrading enzymes==
Calcium oxalate is the main component of urinary calculi. One of the important factors leading to calcium oxalate stone disease is the lack of degradation of the oxalic acid metabolic pathway. Therefore, the use of oxalate degrading enzyme to degrade oxalic acid in the human body has become an important research direction for the prevention and treatment of calcium oxalate stone disease.[2] Studies have shown that with the intake of a large number of foods rich in oxalic acid, the excretion of urinary acid in the urine will be significantly increased. Therefore, reducing intake of exogenous oxalic acid can reduce urinary oxalate excretion, thus significantly reducing the recurrence of stones.[3]
==References==
^ abProperties and Application of Oxalate Decarboxylase Wikipedia, date 2016-12-14.
^ abcResearch progress of oxalate - degrading enzyme in the prevention and treatment of calcium oxalate. Wikipedia article, date 2016-12-14.
^The Latest Development of Preventive Treatment of Calcium Oxalate Calculus. Wikipedia article, date 2016-12-14.
I've nowiki-ed all the section headers, since I don't want them messing with the WP:RDS table of contents or confusing the archiving bot.
Two questions: were all my changes improvements (or did I damage something unknowingly), and what else can be improved? The final sentence in "Brief introduction" is particularly opaque to me; I'm not sure if it's saying the oxalic acids oxidase and decarboxylase, and formyl-CoA decarboxylase, or if it's saying the compound "oxalic acid oxidase", the compound "oxalic acid decarboxylase", and the compound "formyl-CoA decarboxylase", or something else; oxidase and decarboxylase don't appear to me to be kinds of oxalic acids, but I'm completely out of my league here. Nyttend (talk) 14:15, 18 March 2017 (UTC)[reply]
I made a few changes to the article and created the talk page. One change was to remove the erroneous and confusing "polymer proteins", which I hope makes the final sentence of the introduction clearer.--Wikimedes (talk) 05:59, 19 March 2017 (UTC)[reply]
Writing articles like this takes time - but some of the scut work like transferring references from other Wikipedia articles cited should be easy, if not glamorous. I sympathize with the original poster just wanting to link the articles rather than screw around grabbing references out of them. There are some things like Oxalate CoA-transferase and Oxalyl-CoA decarboxylase that would bear mentioning, and it seems inevitable to mention bacteria responsible for protection against kidney stones, but also oxalate growth medium (maybe there's a better name?) used to test for certain bacteria. This can be a substantial article... Wnt (talk) 23:56, 18 March 2017 (UTC)[reply]
I couldn't transfer the references because I couldn't find them; none of the articles I checked, none of the articles mentioned in the citations, appeared to have such citations. My question with the links was basically "which of these articles covers the intended meaning in this spot of text" and thus "which ones should be linked here". Nyttend (talk) 00:32, 19 March 2017 (UTC)[reply]
pH stands for the power of hydrogen. H+ is hydrogen ion in aqueous solution. To calculate pH, you need to take the negative logarithm of the ion concentration. 50.4.236.254 (talk) 02:17, 19 March 2017 (UTC)[reply]
pH explains how it is calculated. 50.4 has given you the wrong answer (well, mostly wrong. There's some negative logarithming going on there, but he doesn't tell you WHAT is being negative logarithm. An ion is not a number, and cannot be logarithmed.) If you want the right answer, read the article on pH. --Jayron3202:22, 19 March 2017 (UTC)[reply]
I live at 40 degrees latitude and -83 degrees longitude. There are a lot of grocery stores here. But some things aren't local. Avocados, for example, come from California or Mexico. Oranges may come from Florida. There are countless corn fields here. And there are many coniferous trees and dandelions and cattails, so I may be able to gather pine nuts. I wonder if I may store them in a safe space for the winter. If I want to eat local, then what should my diet be? What should I do about the winter? 50.4.236.254 (talk) 02:53, 19 March 2017 (UTC)[reply]
Wikipedia has an article titled Local food which explains some of the benefits and pitfalls thereof. Please do not solicit opinions from the ref desks as to what you should do. You can come to those conclusions on your own, and don't need us. We can, however, provide you reading material such as the article Local food. This search contains several links to good locally-sourced foods near your locale. --Jayron3203:04, 19 March 2017 (UTC)[reply]
Not exactly "locally sourced food", per se. But anything in the vicinity, which includes pine nuts. So far, I only know that pine trees, dandelions, and cattails grow here, because I've seen them. I once saw an oak tree too, but I'm not sure if that's common in these parts. I wonder if it's possible to locate specific flora and fauna in the vicinity. 50.4.236.254 (talk) 03:39, 19 March 2017 (UTC)[reply]
Yeah, I know that. I found a website that provides information on how to prepare acorns to make them edible. But I wish to know how various trees - oaks, for example - are dispersed. That may give me some hint to find them. 50.4.236.254 (talk) 04:33, 19 March 2017 (UTC)[reply]
IMHO, a wide variety of food is more important than local sourcing, at least as far as health is concerned. Of course, local sourcing also helps the local economy, at least until everyone else does it and stops buying the food you export. StuRat (talk) 03:46, 19 March 2017 (UTC)[reply]
Eating local is not simply about eating what happens to grow locally - it is about what can be grown locally. If enough people wanted to do it, a lot of those corn fields could easily be used to produce local fruit and vegetables, and to farm animals for meat. If you are the only one wanting to do it, you need to get a bit of land, and grow your own. Wymspen (talk) 12:58, 19 March 2017 (UTC)[reply]
Those coordinates seem to put you at the Ohio State University which certainly has resources to teach you about the local flora, fauna and agricultural practices. Googling "ohio state university" "local food" shows many promising links. Rmhermen (talk) 17:13, 19 March 2017 (UTC)[reply]
Eating local is BS. It is a general postulate of economics that what is cheapest is least detrimental. For example, electric cars "sound" green but they require huge amounts of toxic heavy metals, and the electricity they run on is produced by highly toxic coal-burning electric plants. (That might change with nuclear/fusion and better batteries, but not soon.) The best policy is ALWAYS to buy the cheapest, non-subsidized product. You can pretty-much assume anything from Sacrifornia is the spawn of the Jevil. See "Capitalism" by Reisman. Here's the downloadable PDF http://www.capitalism.net/ (on the left) and the general principle here is division of labor. μηδείς (talk) 17:49, 19 March 2017 (UTC)[reply]
That might be true, but only if the total cost of the entire product life cycle is considered, and if you compare amounts of products that last the same amount of time. Otherwise, plastic forks seem like a better deal than real ones, because each costs less and the disposal costs aren't included. Also, a large part of the reason gasoline cars are cheaper is just economies of scale, so, once electric cars are created on that scale, the price should come down some. (BTW, what is the "J" in Jevil for ?) StuRat (talk) 21:02, 19 March 2017 (UTC)[reply]
Yes, that's why I mentioned "non-subsidized". If transportation is subsidized by taxes, and that is not calculated in, you don't get the actual cost. μηδείς (talk) 01:13, 20 March 2017 (UTC)[reply]
Venezuela#Shortages is an example of what can happen if you don't buy locally. The government there actively discouraged it, instead preferring to export oil and use that money to import food and other goods. Unfortunately, when the price of oil collapsed, this left them without enough cash to import what they need. StuRat (talk) 21:09, 19 March 2017 (UTC)[reply]
Communist governments do encourage people to buy locally, often by having high import duties or just flat out banning many imported products. In fact they have to do so if they want to stay out of the capitalist market. However, shortages are the bane of such countries because of poor planning of production and importation, and dependence on a bureaucracy to manually balance out the market by import/export. I would bet money that Venezuelan people are eating a lot of local food right now, and probably from their very own gardens. 93.138.122.175 (talk) 01:58, 20 March 2017 (UTC)[reply]
I don't think it's true, in general, that communist govs encourage buying locally. For example, they may form huge farm collectives, and grow one item in each province, and expect everyone to buy from that collective. (In addition to the counter-example of Venezuela, we also have China during the "Great Leap Forward", where Mao encouraged farmers to abandon farming and build backyard forges, with disastrous results.) StuRat (talk) 07:26, 21 March 2017 (UTC)[reply]
Buying local is encouraged in developed countries by environmentalists to reduce carbon emissions (see food miles), each individual kiwi fruit is said to require its own weight in aviation fuel to get it from NZ to the UK. Apparently, EU rules prevent the UK government from promoting local produce over imports from other member states. [4]Alansplodge (talk) 11:21, 20 March 2017 (UTC)[reply]
Aqua streaksDifferent-colored areasLong streak in the distance
I was at Key West, Florida the other day and the ocean there has aqua-colored streaks in it. (Well, that is the closest color I know - they are actually a little more greenish than aqua.) This photo is a sample. What causes that? Bubba73You talkin' to me?04:58, 19 March 2017 (UTC)[reply]
I would guess you are seeing white sand bars close to the surface. There are many other factors which can affect water color, but most are more subtle than this. StuRat (talk) 05:12, 19 March 2017 (UTC)[reply]
Sometimes sunlight getting through the clouds creates patches or streaks of brighter color on the water. Here's how you can tell. If it's the bottom and/or seaweed affecting the water color, the patches don't move much. If it's the clouds and/or wind affecting the water color, the patches move or appear / disappear. In the picture I'd guess it's the sun shining on the water through the breaks in the clouds. Dr Dima (talk) 08:34, 19 March 2017 (UTC)[reply]
It's sunlight, as suggested by Dr Dima above. The ship in the middle pic is in shadow surrounded by darker sea. The third pic shows "aqua" sea and sunny beaches on the left; darker sea with beaches in shadow on the right. Bazza (talk) 16:22, 19 March 2017 (UTC)[reply]
It can't be from sand bars but it did look a lot like the top photo at the algal bloom article and like the second photo at Florida Keys ("...tan sediments and microscopic marine organisms (like phytoplankton and algae) discolor the water...") . Bubba73You talkin' to me?00:35, 20 March 2017 (UTC)[reply]
As the ship moved through these waters, the patches seemed to be more-or-less fixed. It was very windy that day - the cold front that resulted in the winter storm in the northeast had come through, so the clouds should have been moving at a pretty good pace. And a few miles out to sea they were gone. For what it is worth, here are two more photos taken about that time: File:Sunset Key Island, Key West, FL, US.jpg
I don't know how to describe this, but I think it's related to overthinking. I have a habit of overthinking and checking things again and again, and oftentimes, this leads to more inaccuracy. When I rely on my "gut response", I get it right most of the time. I remember the time when I was in 9th grade geometry class and how I initially was a B or C student and then jumped to A student. I finished each test or quiz very quickly and accurately, because I stopped overthinking. I answered all the questions correctly, including the bonus questions, so I always got more than 100%. Later, I've heard that my instructors would caution students about overthinking. So, this phenomenon may not just apply to me. I am wondering if there is a neurological basis for "overthinking". 50.4.236.254 (talk) 05:28, 19 March 2017 (UTC)[reply]
It is very useful to be able to think of two different ways to analyse a complex problem and then compare the two solutions. As an example one method might be your gut reaction, and the other a carefully weighted evaluation of the alternatives with score for each attribute. If the two disagree then it can be productive to see why the careful analysis came up with the 'wrong' answer. This can be useful in real life such as choosing where to live, not just engineering and so on.Greglocock (talk) 07:33, 19 March 2017 (UTC)[reply]
I removed someone's ridiculous "hat" that they put on this claiming that this was "psychiatric advice". Their racket is big enough already without letting them take over teaching too - you'd have to give your kids a little bar of gold apiece to cover the day's tuition fees. Wnt (talk) 13:26, 21 March 2017 (UTC)[reply]
Earth-Mars common orbiter
Is it feasible to have a space station orbiting both Earth and Mars such that, periodic arrival takes place during shortest distance between both planets?--Almuhammedi (talk) 07:57, 19 March 2017 (UTC)[reply]
Yes according to Buzz Aldrin who promotes plans for a Mars cycler, a continuously orbiting ferry around Earth and Mars. It would sail endlessly in a complex interplanetary orbit, picking up passengers or sending them off in space taxis when it nears a space station near our Moon or one of the moons of Mars. See The Martian Metro by Frank Braun and Owen Davies, OMNI magazine November 1987. — Preceding unsigned comment added by Blooteuth (talk • contribs) 13:38, 19 March 2017 (UTC)[reply]
Hohmann transfer orbit (and its 'See also' section) may be helpful. Read literally, the OP's question is difficult to follow, but it's not easy to formulate purely verbal descriptions of such dynamic situations without using diagrams. {The poster formerly known as 87.81.230.195} 2.123.26.158 (talk) 18:54, 19 March 2017 (UTC)[reply]
Can we generate unlimited energy?
Is there anything in physics that theoretically allows an infinite power source? Alan Guth refers to the universe as "the ultimate free lunch", so I'm thinking cosmic inflation or some other phenomenon of GR / cosmology.
I have already searched through the refdesk archives to no avail.
quantum fluctuation might also be relevant, as it refers to changes in energy, and it was quantum fluctuations that were amplified in the inflationary epoch that gave rise to the structure of the universe. Or maybe something completely different. Any ideas for an infinite power source? PeterPresent (talk) 09:07, 19 March 2017 (UTC)[reply]
Let's say you have a small region of space with high energy density. If you could trigger inflation in that region, it will expand so you have much more total energy. If you could repeat the process, why couldn't you create arbitrarily much energy? Is it because the energy gradients remain the same (so all you do is magnify unusable heat)? PeterPresent (talk) 10:15, 19 March 2017 (UTC)[reply]
It's not actually known if energy is conserved in General Relativity. See Conservation_of_energy#Relativity. In brief, the Stress–energy tensor of General Relativity does not predict conservation of energy, but also does not include all possible forms of energy (such as gravitational waves). Tensors that do incorporate such things do not behave well. Someguy1221 (talk) 22:57, 20 March 2017 (UTC)[reply]
Even if we had one, it may not be such a good idea. "Free energy" has often turned into profligate use of that energy, with resulting pollution or simply heat pollution. Waste energy ends up as heat, so a society with free energy on offer is likely to become very hot, then using more free energy to run air conditioning and make its surroundings even hotter (air con moves the heat 'outside', but it doesn't make it vanish). Andy Dingley (talk) 10:32, 19 March 2017 (UTC)[reply]
Not if the energy density remains the same. Inflation doesn't change energy density; it changes total energy by amplifying the energy over a much larger volume. PeterPresent (talk) 10:38, 19 March 2017 (UTC)[reply]
Could we not (theoretically) just create a new universe of low entropy (using whatever process created our universe, including cosmic inflation), and migrate? PeterPresent (talk) 10:42, 19 March 2017 (UTC)[reply]
I'm amazed how few people are trying to solve this problem. Once we defeat aging, we will need to find a way to overcome the heat death of the universe if we want to live forever (the SENS approach of repairing the body will require thermodynamic free energy). PeterPresent (talk) 01:53, 20 March 2017 (UTC)[reply]
A thank-you treat for anyone answering this question! :)
Hi all - apologies if this is the wrong branch of RD - it seems closest of the alternatives.
If you by a tub of nice creamy ice cream, and keep it frozen in between servings, it says nice and creamy. If, on the other hand, you let it thaw and then re-freeze it, it gains a solid, ice-like crust. Does the thawing process somehow separate out a coating of water from the ice cream, which then rises to the surface and freezes, or is there something else going on here?
Not really. As Ice cream#Physical properties mentions, ice cream is a colloid. As Ice cream#Production, this is generally achieved by churning the ice cream as it freezes. Our article perhaps isn't the best at explaining this but [5] has what looks to be decent info on the structure of ice cream. If you refreeze it after it's thawed, the structure is lost unless you refreeze it in the same way (which doesn't seem to be recommended for food safety reasons anyway). If you let the ice cream partially thaw you have the same problem but perhaps only on the surface (although even if the ice cream hasn't completely thawed, from my experience it is often still affected mostly throughout if you let it thaw too much). This is an interesting source [6] which talks about the complexities of ice cream melting. Nil Einne (talk) 09:57, 19 March 2017 (UTC)[reply]
There are two processes.
One is simply the growth of larger ice crystals within the mix, crystals grown from the original mix and with the same taste (but not texture). Your ice cream converts to an ice lolly. If you're making ice lollies deliberately, it's usual to use a mix that is physically softer when frozen, to improve its texture - i.e. it freezes to small crystals but won't form single big ones. An ice lolly / popsicle is just a sorbet / ice cream mix that's frozen in one piece, without the churning action that's used for ice cream. They can both benefit from being frozen extra-quickly in manufacture, as that gives less time for large and coherent ice crystals to form.
Another effect is formation of a layer of clear water ice on top of the ice cream. This is atmospheric moisture condensing out and freezing. Don't just keep the ice cream cold, keep the tub sealed airtight too. Andy Dingley (talk) 10:29, 19 March 2017 (UTC)[reply]
Diagram of how metal can recrystallize at nucleation points and then exhibit crystal growth. If you consider the fresh ice cream to be roughly like c), then a few warm ups and re-freezes will leave you with something like d), with a noticeably different texture.We do have three articles on recrystallization (I think they should be merged, but that's an issue for another day). The Recrystallization_(metallurgy) has the best pictures, and may help OP visualize some of the possible changes. SemanticMantis (talk) 16:03, 19 March 2017 (UTC)[reply]
When my ice cream starts to melt, I immediately eat the melted part so it won't refreeze like this, which leads to me "accidentally" leaving it out quite often. :-) StuRat (talk) 13:09, 20 March 2017 (UTC)[reply]
My reaction is that, as we say at the top of the page, we don't answer homework questions, even if you copy them out accurately (which you haven't done here – A uniform 1m long what? Supported where? Suspended 10cm from where?).
However, if you show us your working so far and tell us where you're stuck, someone may give you hints on how to proceed. (The poster formerly known as 87.81.230.195} 2.123.26.158 (talk) 19:06, 19 March 2017 (UTC)[reply]
Have you tried drawing a diagram showing forces on the unnamed object (possibly a rod?), then taking moments about certain points? Let us know how you get on. Dbfirs20:57, 19 March 2017 (UTC)[reply]
During the heat death of the universe, once the energy density becomes low enough, is it possible for quantum effects to cause some or all of matter/energy to spontaneously self-assemble into a singularity and undergo a second Big Bang with the creation of a new universe? If so, if a Big Rip occurs before this, will the new universe therefore be smaller than the current universe? Also, a related question: Is it possible that one or more Big Rip events have already occurred, with the resulting separation of parallel universes from our own part of our universe has already passed beyond the event horizon and thus separated from our own universe into a separate universe (which I thought was what a Big Rip is, even though in fact it's a completely different phenomenon)? 2601:646:8E01:7E0B:5900:99FF:87AF:35DC (talk) 00:16, 20 March 2017 (UTC)[reply]
Its all "bloody" theory! Even the frequently refered "first" Big Bang is. There is some evidence that supports such theories, including logic developements in the far future but there are also some facts that dont fit. More obviouse against all the theories even ist the fact that humanity has merely started to take "the big picture" of our universe. --Kharon (talk) 16:38, 20 March 2017 (UTC)[reply]
One issue with this idea is that it proposes a giant black hole in a spacetime and pictures that spitting out (I presume) Hawking radiationinto the spacetime it came from, i.e. from a distinct center. But the Big Bang is thought to have had no center (or rather, it was everywhere) - all the stars have moved away from it only in time. But there are a lot of wacky "baby universe" theories where universes come out of black holes, "brane" collisions and so forth. I don't know what is relevant and what is just mental masturbation. Wnt (talk) 13:32, 21 March 2017 (UTC)[reply]
Well, it's a weeping willow, but there are several kinds. Our article redirects to Salix babylonica; but in England, the Salix alba 'Tristis' is the most common weeping willow.[7] Our article on that says that the Salix 'Chrysocoma' hybrid "is the most popular and widely grown weeping tree in the warm temperate regions of the world". However, the trees from England and New England seem to get on all right in each others climates, so the Salix alba cultivar seems likely to me. Alansplodge (talk) 14:02, 20 March 2017 (UTC)[reply]
By the way, Salix babylonica doesn't come from Babylon (now Iraq) but refers to Psalm 137: "By the rivers of Babylon, there we sat down, yea, we wept, when we remembered Zion. We hanged our harps upon the willows in the midst thereof", [8] although newer translations have "poplars" instead. [9]Alansplodge (talk) 14:02, 20 March 2017 (UTC)[reply]
Interesting,, and thank you. I didn't realise that the weeping willow was a kind of willow — I thought we just always spoke of willows as "weeping". Had I known that, I wouldn't have come here. And interesting that "poplars" is used; I'm much more familiar with the metrical "By Babel's streams we sat and wept/Our thoughts to Zion turned/There on its willow trees we hung/Our harps which now we spurned". Nyttend (talk) 17:22, 20 March 2017 (UTC)[reply]
Well, as you can see, "weeping willow" is a sort of umbrella term for a willow with pendulous shoots, which encompasses several species, cultivars and hybrids that grow in the same way. That's the problem with using English names for trees, you can never tell exactly what's what - see sycamore for example.
With regard to the psalm: "Biblical scholars point out that these 'willow-trees' were probably Euphrates poplar (Populus euphratica) and not the weeping willows (Salix babylonica) which originated in China.". [10] However, willows and poplars are close cousins, so I don't think King James's translators were too far adrift. As an Anglican, I grew up with the earlier Book of Common Prayer translation which wisely doesn't attempt an identification: "BY the waters of Babylon we sat down and wept : when we remembered thee, O Sion. As for our harps, we hanged them up : upon the trees that are therein". [11]Alansplodge (talk) 17:54, 20 March 2017 (UTC)[reply]
Yes it is possible, that is to say, given that there are a billion hair dryers out there of all sorts of designs and ages, including home made ones, it is quite possible that one might explode. However the standard design has a casing that looks pretty strong compared with the fan, and there's a whole bunch of heating elements and a grill between the fan and the user that would stop shrapnel from coming out 'explosively'. see http://s.hswstatic.com/gif/how-to-repair-small-appliances-24.jpg for an exploded view. Greglocock (talk) 08:36, 20 March 2017 (UTC)[reply]
It's not that unusual - or at least used to be.
For a "pieces fly out" failure you need enough energy to make them fly. In both devices, this is centrifugal kinetic energy of the rotating parts. Hair driers are a lot slower rotating, but they're also more lightly constructed. So both of them have the potential to do this.
Why would a hair drier fail? Mostly because it's a 1960s model, made with the technology of the day. That means a moulded plastic fan, rather than the pressed sheetmetal of earlier designs. Remember The Graduate - plastics, the business of the future. However the materials science of the day hadn't yet caught up with the designs. Although strong when new, continual stresses applied to the heated plastic caused it to become brittle over time. Eventually this could lead to a blade snapping off. A missing blade makes for an unbalanced fan, thus more vibration, and on the other similarly weakened blades, they would often fail immediately too.
This sort of failure was a regular problem for the first retail angle grinders of the late 1970s. These rotate maybe ten times faster than a power drill, two or three time the speed of a car engine at its redline, require a motor cooling fan, yet were initially built from the same materials and standards. The first of these failed regularly. Another fan with notable failure problems was in Formula One and the fan car. Like a reverse hovercraft, this used a pair of fans to suck itself down onto the track. They suffered continual fan failures (and threw the blades out of the back) even with machined aluminium fan blades, until they started using cooling fans from a Chieftain tank engine pack, which had themselves cost Leyland a fortune in development costs.
I don't think they ever broke in public or during a race, but the development history is covered in fair detail in Staniforth, Allan (1983). Race and Rally Car Source Book., along with the Chieftain use. Years later this led me to blag the fans off the AS90 power pack when we needed some indestructible fans at Cummins. They destructed anyway. Andy Dingley (talk) 18:14, 20 March 2017 (UTC)[reply]
Hard to say. It's plausible, but to say any more you'd have to look at specific models and diagnose some actual failures. We're seeing the tangential fans of old hair driers replaced by axial fans, running at higher speeds. These can make the drier smaller and lighter, potentially less noisy too. But it also increases fan stress. We also have the problem today with increasing imports of poor quality fakes and these certainly suffer from poor materials and engineering. Hair straighteners are probably the worst case for hazardous appliances, but the mechanical aspects of fans will have suffered too. Andy Dingley (talk) 12:49, 20 March 2017 (UTC)[reply]
I actually read a number of the hits from that Google search. For the ones that made it clear what sort of abrupt failure they were talking about, none of them described an "uncontained failure like a jet engine", i.e. the fragments of fan smashing through the housing. Some of the accounts did refer to pieces being blown out the air outlet, which, of course, requires a lot less force. --76.71.6.254 (talk) 19:05, 20 March 2017 (UTC)[reply]
It's also exceptionally unusual for a jet engine fan to "smash through the casing". This has barely happened since the collapse of Rolls-Royce, and for similar reasons. Jet engines, at least civil airliner engines, have extensive protection to stop this. If there is an unconfined failure like this, it generally not just a single turbine blade, but the whole turbine disc breaking loose. Running at higher temperatures than the fan or compressor, they're made of denser materials (more steel, less aluminium) and thus have a lot more energy after a failure. Andy Dingley (talk) 19:25, 20 March 2017 (UTC)[reply]
No exact "like" failures. Jet engine rotors are massive, solid metal parts and thus accumulate very high kinetic energy when rotating (very) fast while a fan in a hair dryer will be plastic part with a mass of maybe 5-10 gramms. Also fans usually dont rotate nearly as fast as turbimes. Btw. thats in essence why fans can be made from plastic and turbines cant. --Kharon (talk) 16:22, 20 March 2017 (UTC)[reply]
Iron loss
Hello. The Wikipedia article on iron metabolism says that normal people lose about 2 mg of iron per day, but that people with inflammatory bowel disease lose "more". How much is more? 2x? 4x? 10x? I know that iron loss can vary depending on the severity of the disease, but I'm looking for a rough number here. Thanks. --90.69.12.160 (talk) 08:30, 20 March 2017 (UTC)[reply]
I think loss of iron varies from individual to individual. People only lose iron, because of regular menstual bleeding and intestinal bleeding, and bleeding amount can vary. I found this website that reports that bleeding, perhaps caused by IBD, is the cause of iron loss, but the iron loss can easily be replaced by diet, though people who have IBD just happen to eat less iron. Also, "Chronic intestinal bleeding in IBD may exceed the amount of iron that can be absorbed from the diet, resulting in a negative iron balance." So, the actual amount may vary. Hence the iron deficiency is seemingly caused by the IBD, even though it's really IBD and the diet that both contribute to iron deficiency. Animals are rich in easily absorbable iron, and several plants, including dandelion greens, contain iron. Though, iron found in plants may not be readily absorbed. Though, I suppose your own gastric acid and maybe some lemon juice can aid absorption of iron, but phytic acid can decrease absorption. I think that is one reason why people should really add dressing and properly prepared beans to their salads. Beans that have not been soaked may include high amount of phytic acid and thus result in iron deficiency. 50.4.236.254 (talk) 13:05, 20 March 2017 (UTC)[reply]
Is potassium in plants linked to soil quality?
Many plants seem to contain a lot of potassium. People use potash fertilizer to fertilize the soil. Could it be that the potassium in the potash is converted into potassium in the plant? What happens if an animal corpse is buried right next to or below the plant? Will the plant absorb the animal's nutrients? Will the soil be more nutritious for the plant? 50.4.236.254 (talk) 13:45, 20 March 2017 (UTC)[reply]
Corpses are poor short-term fertilisers, although there are traditions of planting a sheep-sized animal beneath new trees, wrapped in a sack, as a slow-release fertiliser on a longer time scale.
A better fertiliser is bonemeal. More of the useful minerals, in a form with a high surface area and so more easily accessible. Less of the deliquescent fats that aren't. The traditional "blood, fish and bone" is particularly useful.
If you bury a corpse, especially too shallow, it may actually scorch the plants on the surface. They may give rise to a "fairy ring" structure, where fungi (which do enjoy a good corpse) emerge around it, but they in turn discourage green plants. Modern "green burials" tend to use a permeable "pod", which acts to delay the effluents travelling into the surrounding soil until the microoccupants of the pod have had a go at them first.
If you're really after bulk potassium, then wood ash is a favoured source. You can also grow a fast-growing crop of a green mulch, like comfrey or even nettles, then apply these or convert them to a liquid first. [12] Famously nettles are rare in the wild (English countryside) but clumps of them are an indication of previous settlements, wood fires and the increased soil potassium that produces. If you walk in heathlands around abandoned farmland (Ireland is good for this) then a sudden clump of nettles will often reveal a few stones in the middle of it, and the last remnant of a cottage. Andy Dingley (talk) 14:41, 20 March 2017 (UTC)[reply]
I wonder if corpses can be fed to the scavengers, and the scavengers will lick the muscles and fats and organs off the bones, and then the bones will be left on the surface. Then, the bones may be grounded up into bone meal. I've read that a forest that has not been touched by humans can grow really big trees, but the superficial soil is very low quality. I wonder if it's possible to convert cemeteries into big forests and dump human bodies into these forests to be eaten by scavengers and decomposers and absorbed by the plants. 50.4.236.254 (talk) 14:53, 20 March 2017 (UTC)[reply]
Green burials in woodlands are increasingly a thing, but the scavengers are microbial and underground.
Tree size depends on species and climate, not humans. Also the soil around the trees - trees that deposit leaves to produce leaf litter in a climate to rot it down can have abundant undergrowth around them. Some species (most conifers) don't, and some, like beech keep other trees away by shading or walnuts produce juglones that are toxic to other plant species, all leading to bare soils low in organic material. Andy Dingley (talk) 15:46, 20 March 2017 (UTC)[reply]
Almost all forests in the contiguous US have been cut down since Europeans arrived. If you've seen Back to the Future you'd see that the average American probably lives in a suburb that was farmland only a few decades before and they often have treeless lawns. The routes between major Mid-Atlantic states cities are often lined with trees barely decades old even in long rural stretches. The UK actually has parks, streets, privacy walls of trees etc. over 400 years old so possibly you're more used to tree size not being so correlated with remoteness. You have thousand year oaks don't you? Sagittarian Milky Way (talk) 18:57, 20 March 2017 (UTC)[reply]
Yes, we have a few thousand year old oaks. They're generally smaller than a 200 year old oak.
Apart from the non-UK-native firs, sequoia etc. (our tallest trees) that grow vertically upwards, branching forest trees are often limited by competition. So human intervention in felling the competition is as likely to make them larger (if fewer). Three of the tallest ten trees in the UK are on Lord Armstrong's Cragside estate and they're only about 150 years old. Andy Dingley (talk) 19:11, 20 March 2017 (UTC)[reply]
To answer the question, "Could it be that the potassium in the potash is converted into potassium in the plant?": Yes, potash and other forms of fertilizer containing potassium are added to soil for the specific purpose of providing potassium to be incorporated into a plant as it grows (potassium content is the the "K" in the NPK labeling of fertilizer). Deli nk (talk) 15:01, 20 March 2017 (UTC)[reply]
Yes, soil quality in part depends on potassium available. See Plant_nutrition#Potassium for an overview and more detail. In particular, "Potassium does not enter into the composition of any of the important plant constituents involved in metabolism, but it does occur in all parts of plants in substantial amounts... Potassium is outstanding among the nutrient elements for its mobility and solubility within plant tissues."
On using corpses as fertilizer: Blood meal and bone meal are common organic fertilizers, and are often key components of a soil management plan. You can find many brands of these dead-animal-derived fertilizers on the shelves of any decent garden center, here's an example at Walmart [13]. Bone meal is not especially fast acting at putting phosphorus into the soil: that's basically the point, sustained slower release over a long period of time. Blood meal is faster acting, but mostly contains N. SemanticMantis (talk) 20:00, 20 March 2017 (UTC)[reply]
Does raw sewage enter tap water during a hurricane in florida?
I was reading this article from florida saying not to drink or bathe in tap water during a hurricane and have heard conflicting stories about why this is, some saying raw sewage can enter tap water, others saying it is due to other reasons which they never explain in detail. Can anyone clarify what the real reason is?--Sara203040 (talk) 17:26, 20 March 2017 (UTC)[reply]
Tap water likely comes from a municipal water supply, but also refers to a local pumped well. Either way, that water supply comes from a source. During a flood, the source can become contaminated with raw sewage, as noted in the question, as well as chemicals, toxins, and decaying animals. It is not possible to say that there will be a specific contaminate, but there is a possible contaminate. Further, water supply lines often lose pressure during a hurricane. Power goes out. Pumps turn off. There is no water being forced into the lines, so the lines back up. It is possible for lines to break also. Pressure in water lines helps reduce contaminates, which is why you always get a boil advisory when a supply line is shut off or repaired. There are certainly more causes for contamination. So, if someone were to mention yet another method contamination, it isn't a "conflicting story." A conflicting story would be to claim that it is not possible for a flood to contaminate a water supply or a hurricane to drop pressure in a supply line. 209.149.113.5 (talk) 17:45, 20 March 2017 (UTC)[reply]
If you happen to have a horrid combined sewer system, as we do, rainwater and raw sewage mix together, so that during heavy rain the sewers back up in our basements and flood out into the lakes and rivers. Hopefully the water treatment center will clean up any sewage that gets into the intakes, but there's still breaks in the water mains where all that sewage can get in. StuRat (talk) 07:13, 21 March 2017 (UTC)[reply]
On a large scale, gravity is used for movement of water throughout a city. Look at the water tower design. You pump water up to the top of the water tower. Then, gravity pushes it to all of the houses. If flood water is higher than the level of the reservoir, even if it is enclosed, the water can flow the wrong direction - flowing up into the reservoir instead of down out of it. That is because the water level outside the reservoir is higher than the water level inside it. Now, what kind of water flows in? Could simply be rain water. Could be sea water. Could be raw sewage. 209.149.113.5 (talk) 11:48, 21 March 2017 (UTC)[reply]
How would flood water enter the reservoir though? Even if there is a combined sewer system, the pipes for sewage and fresh water are separate.--Sara203040 (talk) 21:38, 21 March 2017 (UTC)[reply]
How would seawater affect the skin if we showered daily with it? Do people on sail boats use it, or, do they load drinking water for it? (seems like a big hassle to me, if our skin is not heavily affected by seawater).--Hofhof (talk) 20:53, 20 March 2017 (UTC)[reply]
And why is hypertonic better for showering than hypotonic or isotonic solutions? Wouldn't it dry out the skin if used daily? --Hofhof (talk) 23:20, 20 March 2017 (UTC)[reply]
Whatever the medical benefits are it does not make for a great shower, subjectively. Soap doesn't lather, and when you dry off you still feel a bit sticky. It's better than nothing, and better than typical bore water in the Outback, but that ain't saying a whole lot.Greglocock (talk) 04:47, 21 March 2017 (UTC)[reply]
A good compromise is to shower with sea water, then take a quick rinse with fresh water. So, you mostly use salt-water, but don't end up smelling like fish. StuRat (talk) 07:08, 21 March 2017 (UTC)[reply]
As for the sailboat question... When I was much younger and sailed from North Carolina to Bermuda to Puerto Rico, and back to North Carolina, we bathed in the water when the sea was still. You do come out covered in salt, but you have to remember that you are working on a boat in the open sea. You sweat profusely. So, your internal saltwater flushes away the sea water. Overall, the amount everyone sweats could count as a saltwater shower itself. Of course, this was a working sailboat. I've been on sailboats (sail yachts to be more precise) since. They have freshwater showers, tubs, and swimming pools. That is a completely different type of boat. 209.149.113.5 (talk) 11:44, 21 March 2017 (UTC)\[reply]
In times of yore, sailors on sailing ships just pulled up a pail of sea water and doused themselves when they needed a wash. People that have only showered in tap-water may find the saltiness odd at first and want to shower it off with fresh, because the skin feels different from what they are used to. Any editors that may have become collage drop-outs (so they could spend every day surfing) will back me up, that as a teenager I didn’t feel the need to shower after. Also remember, that these sailors (and surfers) ate a lot of sea-food. So they didn't suffer from dry skin, which some people on vacation complain of when in contact with sea-water. --Aspro (talk) 20:43, 21 March 2017 (UTC)[reply]
(edit conflict) Well the easiest way is to just measure your velocity relative to something on the furthest edge of the visible universe... but I'm guessing you wanted a real answer. We have nice articles at Spacecraft propulsion and interstellar travel. The problem with most spacecraft propulsion technologies getting you to near the speed of light is that to go say twice as fast, you need to carry way more than twice as much fuel, since you have to get the fuel to make that extra speed bost, as well as even more fuel to get the extra fuel to that point. As a result, the fuel cost goes up exponentially, and that's not even taking into account relativistic effects (see Tsiolkovsky rocket equation). So a conventional chemical rocket or even an ion engine are probably no-goes if 99% c is your goal. An antimatter rocket may be able to reach near the speed of light, and the speed of a laser propulsion system is not limited at all by how much fuel you can carry. Someguy1221 (talk) 00:57, 21 March 2017 (UTC)[reply]
But where are you going to get that much antimatter? And for laser propulsion, doesn't a laser beam spread out, making its intensity drop the farther the sail gets away? Bubba73You talkin' to me?02:59, 21 March 2017 (UTC)[reply]
In the case of antimatter, you run into the first problem that trovatore lists. Regarding laser propulsion, it's not without problems! Simply that fuel is not one of them (well sort of. If you are using a laser-ablative propulsion system, then you still have fuel, but you're only carrying the inert propellant and not the power source). This is why our articles link to sources giving a "top speed" if you will. Any given system has a distance or speed beyond which it doesn't work, for one reason or another. Someguy1221 (talk) 03:51, 21 March 2017 (UTC)[reply]
In theory any engine and fuel that produces acceleration long enough would achieve something close to that speed eventually. In reality tho this seems rather pointless, because the only usefull task would be to travel somewhere and for that you would have to decelerate more or less the same amount eventually. So as it doesnt make much sense to reach the highest possible "top speed" in travels today it would not make sense for space exploration alike. Any aproach would mainly focus on economical problems to solve. So your question seems rather pointless. --Kharon (talk) 04:08, 21 March 2017 (UTC)[reply]
Given a hypothetical engine capable of constant acceleration changing at mid-course when to deceleration, by the Equations of motion often referred to as the "SUVAT" equations, where "SUVAT" is an acronym from the variables: s = displacement, u = initial velocity, v = final velocity, a = acceleration, t = time:
I think you need to balance the chemical equation first. See gallium arsenide for details. You may be assuming a 1:1 ratio, because it appears that way, even though the gallium arsenide article suggests that it's not really 1:1. 50.4.236.254 (talk) 03:32, 21 March 2017 (UTC)[reply]
Yes. But this chemical formula most closely matches your situation. 4 Ga + As 4 → 4 GaAs or 2 Ga + As 2 → 2 GaAs With this balanced equation in hand, try recalculating everything and see what you get. 50.4.236.254 (talk) 04:16, 21 March 2017 (UTC)[reply]
I appreciate your help, but don't understand the difference. The only thing that would affect the calculations is the relative molar or mass amounts of each reactant. If you double or quadruple each reactant, you're still ending up with the same relative amounts. Also, when the book shows a reaction like that it doesn't assume any need to change it unless explicitly stated. 69.22.242.15 (talk) 10:22, 21 March 2017 (UTC)[reply]
Given the apparent level of the question (this is a high-school or freshman-college general-chemistry course), I agree that the intracacies of figuring out the formula of an intermetallic product are probably well out-of-scope. OP, you can probably keep yourself from getting confused and from making easy mistakes in more complicated problems by following your book's example to use "g/mol" for atomic or molar masses rather than "g" for actual measured amounts of substance. For example:
X mol *
Y
g
= X*Y g
mol
has correct algebra of the units as well as correct arithmetic of the numbers, rather than having to remember what your "g" represents in different contexts). See Dimensional analysis, and especially its "The factor-label method for converting units" section, for more details. DMacks (talk) 12:55, 21 March 2017 (UTC)[reply]
I agree. I'm pretty sure I have this textbook around my office...will look for errata and solution-manual to see if there are any further details later today. DMacks (talk) 13:22, 21 March 2017 (UTC)[reply]
Is trophic level based on what keeps an organism alive instead of what the organism can eat?
Humans can drink urine or eat feces, if they want to. There doesn't seem to be anything stopping them. Since they can eat feces and drink urine, regardless of nutrition or toxicity, does that mean that their trophic level includes coprophagia? Or is trophic level based on what keeps an organism alive? 50.4.236.254 (talk) 05:27, 21 March 2017 (UTC)[reply]
Defining a trophic level is ultimately somewhat arbitrary. Humans are frequently referred to as apex predators, but then there are vegans. Even apex predators in nature will eat carrion when hungry. And many decomposers will behave as facultative parasites and pathogens when the opportunity arises. From my own observation, occupancy of a level seems to be defined as what an organism mostly does. Someguy1221 (talk) 07:02, 21 March 2017 (UTC)[reply]
It is a problem. Both pubmed and google scholar list many papers studying cathelicidin resistance (though some of the papers that show up in such a search are about resistance of cathelicidin to proteases). Someguy1221 (talk) 06:57, 21 March 2017 (UTC)[reply]
Like anti anxiety pills, anti depressants. I've read lots of people say it does nothing. I used quite a number of anti depressants and all I feel is sleepy. I also used phenibut and it does NOTHING. I feel like they are all scam by greedy pharmaceutical companies. Has there been any investigation into the effectiveness of mind altering medicine? If you know any articles please link. Thanks. Money is tight (talk) 07:59, 22 March 2017 (UTC)[reply]
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