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Tuesday, October 24, 2017

If large atoms are formed in stars and then spread out in the universe, why are heavy metals found in high concentrations, rather than distributed evenly, throughout the earth?

If large atoms are formed in stars and then spread out in the universe, why are heavy metals found in high concentrations, rather than distributed evenly, throughout the earth?


If large atoms are formed in stars and then spread out in the universe, why are heavy metals found in high concentrations, rather than distributed evenly, throughout the earth?

Posted: 24 Oct 2017 02:28 AM PDT

Is it possible to see the flag that was left on the moon?

Posted: 23 Oct 2017 03:43 PM PDT

Why do your eyes feel heavy when you’re tired?

Posted: 23 Oct 2017 12:41 PM PDT

If the moon were pear-shaped, which end would face the earth?

Posted: 23 Oct 2017 02:16 PM PDT

Would it be the small end because it has "extra" mass ("outside" the sphere) or the big end because it has the center of gravity?

submitted by /u/fwubglubbel
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If there's clockwise and counterclockwise in three dimensions, is there an analogous third-clockwise in four dimensions?

Posted: 23 Oct 2017 04:27 PM PDT

In both two and three dimensions, there's only two directions to rotate things: clockwise and counterclockwise. Is there an analogous third-clockwise in four dimensions? Or is it still only clockwise and counterclockwise?

And I guess a follow up would be: why are there only two ways to rotate in 2D and 3D instead of say three or only one? And do higher dimensions still only have two ways to rotate things?

And I guess this is really more of a math question than a science question, but I suppose it's relevant to physics.

submitted by /u/BroccoliHelicopter
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What's the difference between a dissection and a necropsy?

Posted: 23 Oct 2017 06:15 PM PDT

All of a sudden I don't see a difference between the two.

submitted by /u/immr_meeseeks
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Is electron spin and orbital momentum the sole cause of magnetism? And related questions.

Posted: 23 Oct 2017 09:26 PM PDT

Second similar question is do electron's magnetism have an orientation? I understand that electron's are not spinning balls but they have a magnetic field and what not so wouldn't they have a North/South orientation in some physical spacial dimension? If this is the case how does that effect magnetic properties? Tied to this then is how does the physical orbital "direction" or shape affect magnetism? Lastly, how does this relate to macroscopic objects such as the earth and it's magnetic field? Is it's magnetic field caused by this same thing or is it because it's a rotating charged body which then does this charge come from uneven protons/electrons?

P. S. I have a reasonable conceptual understanding of particles, moderate conceptual understanding of classical physics. However no math background in those, but I can understand some math.

submitted by /u/Ug1uk
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What are known technical hurdles that AlphaGo Zero would have to overcome before being able to play go on arbitrary graphs?

Posted: 23 Oct 2017 07:56 PM PDT

AlphaGo Zero recently demonstrated impressive success in AI by training a winning neural net from only self-play. I read somewhere (can't find the original source) that there is reason to be skeptical of how much of an advance this really is, since the resulting network won't be able to generalize its knowledge to even slightly different games, like "go on an 18x18 board". It seems like one possible next step is to fix the rules but to allow the topology to vary. My limited knowledge of neural nets suggests that this would be hard.

What are specific hurdles to constructing a neural net that can play go over arbitrary graphs (supplied at the beginning of game play)? What are avenues of exploration for overcoming them?

submitted by /u/rpglover64
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How would inserting a floating balloon into the atmosphere of a planet from space be technically different from landing a craft on the rocky surface of a planet from space?

Posted: 23 Oct 2017 12:03 PM PDT

So I know there are a some important technical differences between landing a craft on Earth (which has a moderate atmosphere) versus landing a craft on Mars (which has a thin atmosphere). If my understanding is correct, the thinner atmosphere of Mars poses particular challenges because it's not thick enough to make use of air braking, but it is thick enough to cause frictional heating.

I've also heard that landing a craft on Venus is damn near impossible because the heat, pressure and chemical composition of the atmosphere at ground-level basically melts any craft we might send to its surface.

And I've read briefly about proposed missions to Venus that involve floating a lighter-than-atmosphere vessel in the upper layers of the venereal atmosphere, where the heat and pressure and causticness of that atmosphere won't be so severe.

But how would we go about inserting a balloon-like craft from orbit into the upper atmosphere of Venus?

submitted by /u/CalibanDrive
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What classifies a sickness as the "flu" and why do we have flu seasons?

Posted: 23 Oct 2017 02:15 PM PDT

Would matter made of tetra and penta-quarks have their own periodic tables?

Posted: 23 Oct 2017 11:19 AM PDT

If atoms in an element have protons, neutrons, and elections, and get their chemical properties depending on their atomic number, would, in theory, "atoms" made or tetra or penta-quarks, make up a different nucleus and replace a neutron and or proton?

submitted by /u/Phlegmsky
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People cannot live in Pripyat, but they live in Hiroshima and Nagasaki. What is the difference in atomic after-affects (radiation) in a bomb context versus that of a reactor meltdown context?

Posted: 23 Oct 2017 12:59 PM PDT

How much beta/gamma radiation does the core of a star that has undergone supernova emit?

Posted: 23 Oct 2017 07:30 PM PDT

Specifically how would it compare to say, a typical nuclear reactor running at full capacity?

I wonder because it seems like in the entirety of a star there would be a very small amount of fissile material. How much plutonium or other fissile material would there be in a stellar core? How much is in a typical reactor?

Asked before but the context here is a little different.

submitted by /u/MostlyCarbonite
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What happens to your body after getting a vaccine?

Posted: 23 Oct 2017 06:37 PM PDT

After getting a flu shot, I got curious about what happens as soon as the needle punctures the skin and what happens to your body as the vaccine works its way through/develops (?).

Sub-question: What happens when you come into contact with whatever you were vaccinated for?

submitted by /u/TheDrKillJoy
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How big would a ball have to be to start rolling due to the curvature of the earth?

Posted: 23 Oct 2017 04:15 PM PDT

Also would it keep rolling forever?

submitted by /u/profuttbuck
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How are exoplanet host stars distributed by spectral class, and how does that compare to the distribution of stars generally?

Posted: 23 Oct 2017 03:31 PM PDT

The visual processing region of the brain is located on the opposite side of the brain to the eyes, does this distance cause lag in our visual perception?

Posted: 23 Oct 2017 05:40 PM PDT

Is power being drawn by an appliance that is plugged in but switched off?

Posted: 23 Oct 2017 03:22 PM PDT

Do appliances draw any power, i.e. I am charged for power usage, when they are plugged in to an outlet that is switched on but the appliance itself is switched off and not on standby? Also does an outlet draw power if it has nothing plugged in but is switched on?

submitted by /u/ThatsTheWaySheGoes
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What are the physical implications of Maxwell’s relations (of thermodynamics)?

Posted: 23 Oct 2017 10:03 AM PDT

For example, the one derived from enthalpy:

(∂T/∂p)_S = (∂V/∂S)_p

The answer I'm looking for is not "the rate of change in temperature respective to pressure at constant entropy is equal to the rate in change of volume wrt entropy at constant pressure". This I already know.

What I'm trying to understand is more so the physical implications of these equations.

For example, the constant pressure heat capacity Cp is defined similarly through a partial derivative as (∂H/∂T)_p. What this directly represents is the change in heat respective to the change in temperature while holding pressure constant, however in a gas it is much more significant when understood in terms of intermolecular interactions; complex gas molecules can absorb some of the incoming energy through their vibrational states/bonds/etc, which therefore lessens the change in temperature due because not all of the incoming energy goes to influencing ΔT.

I am primarily trying to understand this in terms of gases, as the course I'm taking is Physical Chemistry rather than thermo, and so the vast majority of what we've been discussing involves gases. However, any interpretation would help greatly.

submitted by /u/G-Quadruplex
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How do you interpret Heisenberg's Uncertainty Principle for wave functions?

Posted: 23 Oct 2017 11:22 AM PDT

Okay so I understand the idea behind Heisenberg's Uncertainty principle when applied to macroscopic objects, like a ball - if you were to see a clear picture of a ball, you could accurately identify its location, but not its momentum, and if you happened to see a blurry picture of a ball, its location would be less well defined, but the blur direction would allow you to accurately identify its momentum.

However, I can't quite grasp the a proper understanding of the the Uncertainty Principle when applied to wave functions. I stumbled across this picture - I understand why the bottom wave function has a more well-defined location than the top wave function, but I can't understand why its momentum is less well defined. Fundamentally, what characteristic of the bottom wave function means it has a less well-defined momentum? If someone could somehow draw parallels between these wave functions and macroscopic objects in this way, that would be fantastic, as I hope I would then understand.

Thanks.

submitted by /u/ThatCosmicGuy
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Monday, October 23, 2017

What is happening when a computer generates a random number? Are all RNG programs created equally? What makes an RNG better or worse?

What is happening when a computer generates a random number? Are all RNG programs created equally? What makes an RNG better or worse?


What is happening when a computer generates a random number? Are all RNG programs created equally? What makes an RNG better or worse?

Posted: 22 Oct 2017 11:09 AM PDT

What are the hair follicles doing differently in humans with different hair types (straight vs wavy vs curly vs frizzy etc., and also color differences) at the point where the hair gets "assembled" by the follicle?

Posted: 23 Oct 2017 07:00 AM PDT

If hair is just a structure that gets "extruded" by a hair follicle, then all differences in human hair (at least when it exits the follicle) must be due to mechanical and chemical differences built-in to the hair shaft itself when it gets assembled, right?

 

So what are these differences, and what are their "biomechanical" origins? In other words, what exactly are hair follicles, how do they take molecules and turn them into "hair", and how does this process differ from hair type to hair type.

 

Sorry if some of that was redundant, but I was trying to ask the same question multiple ways for clarity, since I wasn't sure I was using the correct terms in either case.

 

Edit 1: I tagged this with the "Biology" flair because I thought it might be an appropriate question for a molecular biologist or similar, but if it would be more appropriately set to the "Human Body" flair, let me know.

Edit 2: Clarified "Edit 1" wording.

submitted by /u/Mars2035
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What is happening when a chip goes stale?

Posted: 22 Oct 2017 09:28 AM PDT

What "physically" is the wave described in Pilot-wave Theory/Bohmiam mechanics?

Posted: 23 Oct 2017 04:38 AM PDT

In Pilot-wave Theory (de Broglie–Bohm theory), what is the wave that the particle is interacting with? Is it like a quantum field theory wave, one for every particle or type of particle in the universe? Some sort of interaction with space-time? Or some sort of emergent property of the particle itself - in which case how does that differ from wave-particle duality?

submitted by /u/danielchorley
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How do the salt balls form in the Dead Sea?

Posted: 22 Oct 2017 08:28 PM PDT

My parents brought some salt balls back from the Dead Sea and my dad and I got into a discussion about how they form. After a bit of hypothesizing we turned to the trusty internet to see who is correct but we both have come up empty. Can Reddit settle it? How do they form?

submitted by /u/Fireprf
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Do babies in the womb dream?

Posted: 22 Oct 2017 07:07 PM PDT

I mean of course it would have to be at a more advanced stage where the brain is developed to a point but considering pre-born babies do not have any perspective on ... well anything, do they dream?

submitted by /u/LebronKingJames
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What happens to concrete on a molecular level when it cures?

Posted: 22 Oct 2017 05:20 PM PDT

I know it does not just dry out the water, otherwise buildings would melt when it rains. What exactly happens? Thanks.

submitted by /u/sebasvel
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Stepping down AC voltage and converting to DC comes with losses. LED light bulbs get pretty hot. Are they really saving energy?

Posted: 22 Oct 2017 08:23 PM PDT

Is there any reason to wash your clothes in separate loads/“with like colors”?

Posted: 22 Oct 2017 07:15 PM PDT

Often you'll see clothing tags advise consumers to wash "with like colors," and my own mother has a "light" load, "dark load," "jean," "dressy," "red" (if it's big enough), and "intimates/sheets/towels/gym clothes" (stuff with a lot of contact with the smellier parts of you). However, my fiancée just throws in as much as the washer can hold. Have I been over-complicating clothes washing all my life?

(Fiancée is a man, uses the extra e because I proposed to him, we know it's Frenchmatically wrong)

submitted by /u/SlippingStar
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How come light has momentum when it travels at the speed of light(c)?

Posted: 23 Oct 2017 05:33 AM PDT

Using the relativistic momentum equation we see the result is zero momentum p=mv/√(1-v2 / c2 ). v=c so the result would be mv/0, undefined.

submitted by /u/samdude17
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Is the human genome adapting to our modern diet?

Posted: 22 Oct 2017 02:23 PM PDT

It's quite clear that modern humans in industrialized countries eat a far different diet than the hunters and foragers of antiquity. I would guess that natural selection pressures (such as deaths due to heart disease or diabetes) and sexual selection pressures (such as an aversity towards obesity) have had some effect on the modern human genome. Has there been a measurable effect on allele frequency?

submitted by /u/TristanBomb
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How exactly does Earth's magnetic field protect us from solar flares?

Posted: 22 Oct 2017 06:49 PM PDT

If staring at the sun will damage our eyesight, why aren't our peripherals damaged severely from all the time the sun spends there?

Posted: 22 Oct 2017 02:44 PM PDT

Given the increase in mobile data speed from 2G to 3G to 4G, is there a theoretical limit? If so, are we close? Or just getting started?

Posted: 22 Oct 2017 03:21 PM PDT

Do more devices result in thinner slices of pie?

submitted by /u/lessnonymous
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Why do European bottles say "Fill level due to technical reasons" but in Asia they are filled to the top?

Posted: 22 Oct 2017 01:07 PM PDT

Assuming they use the same machines to bottle, there don't seem to be any technical issues preventing them from filling it up to the top.

submitted by /u/k_thien
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In what language were programming languages written?

Posted: 22 Oct 2017 03:27 PM PDT

What causes quantum fluctuations?

Posted: 22 Oct 2017 02:39 PM PDT

If virtual particles are caused by fluctuations in quantum fields, then what causes those fluctuations?

submitted by /u/JosephTheMlem
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Orbital slingshot? (what is it and how does it work?)

Posted: 22 Oct 2017 07:23 PM PDT

So I'm having a bit of a mind blank moment, but I need some help with being explained how and what orbital slingshots are. I would've asked r/ExplainLikeImFive, but I feel like it would be more appropriate here. Giving an easy to understand answer would be appreciated though !!

thankyou :)

submitted by /u/Rachaelvl500
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How is Mills's constant calculated? How does it relate to the Riemann hypothesis? Why don't we know if it's rational?

Posted: 22 Oct 2017 11:37 AM PDT

Is fire affected by momentum?

Posted: 22 Oct 2017 10:15 AM PDT

Say if you were to drop a fire 50 ft on to the ground in a box where no wind would put the fire out. Would the fire hit the ground and then compress due to momentum? Or would it keep burning normally (upright flames)

submitted by /u/SheanGomes
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Sunday, October 22, 2017

Do hydrogen isotopes affect chemical structure of complex hydrocarbons?

Do hydrogen isotopes affect chemical structure of complex hydrocarbons?


Do hydrogen isotopes affect chemical structure of complex hydrocarbons?

Posted: 22 Oct 2017 06:10 AM PDT

Hello!

I am wondering if doubling/tripling of the mass of hydrogen in complex hydrocarbons has a chance of affecting its structure, and consequently, its reactability.

Furthermore, what happens when a tritium isotope decays in a hydrocarbon to the hydrocarbon?

Finally, as cause for this whole question, would tritiated ethanol behave any differently to normal ethanol?

submitted by /u/Hoihe
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How far can a big passenger aircraft (for instance an Airbus A340) glide after catastrophic engin failure?

Posted: 22 Oct 2017 03:03 AM PDT

I imagine "not far" being the tl;dr, but I was wondering how would it look from the ground? If loaded close to capacity, would it look little like a rock falling from the sky?

submitted by /u/docsleepy
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Is there a difference in suicide rates between people who have already had children and those who haven't?

Posted: 21 Oct 2017 09:20 PM PDT

Because on one hand, having children fulfills our biological goal so I'd imagine there would be less incentive to stick around if things came to that, but on the other hand there could be increased incentive to stick around to care for and protect the kids. Is there any discrepancy between the groups that becomes apparent on a large scale?

submitted by /u/AbsolutelySwedish
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Why do electrons have a constant mass?

Posted: 21 Oct 2017 11:28 PM PDT

So as far as I understand, electrons can gain and lose a quantifiable amount of energy in the form of photons. Because photons have energy, they must have mass because having a zero mass would result in energy being zero due to E=mc2. However, this implies that electrons in higher energy orbitals would have more mass than those in lower orbitals because they have either absorbed or emitted energy in the form of photons. What equalizes the mass of the electron for the photon being either lost or gained?

Also, if an electron is gaining/losing mass as photons are emitted and released, where is the charge of the electron stored? The photon isn't a charged particle/wave/whatever it is, so the electron isn't losing or gaining charge despite losing mass.

Sorry for the lengthy question!

submitted by /u/Malsirhc
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Why don’t we use salt water for toilet water? Wouldn’t it save millions of gallons of freshwater?

Posted: 21 Oct 2017 07:23 AM PDT

If you drop something on a solid, does it ripple like a liquid would except much less noticeably?

Posted: 21 Oct 2017 01:01 PM PDT

I thought of this when I was dropping some objects into sand, the sand would shift outwards kind of like a ripple.

submitted by /u/XH192
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Why do some trees leaves turn red some yellow and some orange and if a tree is red this year then is it always red or can it be yellow next year?

Posted: 21 Oct 2017 08:43 PM PDT

How do we calculate the exhaust speed of ions in a Hall-effect thruster ?

Posted: 22 Oct 2017 07:03 AM PDT

Can there be anything higher than a pH of 14 or lower than a pH of 0?

Posted: 21 Oct 2017 08:26 AM PDT

How can we prove that earth is rotating?

Posted: 22 Oct 2017 03:13 AM PDT

Aside from the Foucault pendulum, how can we prove that earth is rotating?

My friend showed me a video of a gyroscope which keeps its position by hours. I thought a gyroscope keeps its horizon no matter what, but with a rotating earth, it should have been seen as tilting after a couple hours.

Am I not right? Do I miss something here?

Is there an another way of proving that earth is rotating and round physically? (Without the satellite images etc.)

submitted by /u/contruiga
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Why are sloths so slow?

Posted: 21 Oct 2017 12:01 PM PDT

Why is Ruthenium's electron configuration [Kr] 5s1 4d7?

Posted: 21 Oct 2017 08:28 PM PDT

Why is it more favourable than [Kr] 5s2 4d6? Also what would the electron configuration for Ru 4+ look like?

submitted by /u/ItsnotEasyman
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Is the low dosage of cosmic background radiation we are constatly exposed to a driver of evolution?

Posted: 21 Oct 2017 08:25 PM PDT

Will sterilisation with gamma rays not make the product radioactive or destroy the product?

Posted: 21 Oct 2017 09:59 AM PDT

I was told yesterday that sometimes drugs are sterilised using gamma rays because some drugs can't handle being heated. Then he added that it's also used for food!?

Is there not a risk of the drug, food or packaging becoming radioactive? Or will the rays not alter the drug or the food?

I am also wondering if this done in very controlled facilities? But he said it was very common, but I thought it would be too expensive!?

submitted by /u/DiegoRez
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Human fetal development: When does the uterus start to form?

Posted: 21 Oct 2017 02:11 PM PDT

I know why men have nipples, and why some men have supernumerary nipples. I know that the ovaries and the testicles started off as the same primitive structure. I know that the same erectile tissue and urethra in women combine to become the penis in men.

Is there an equivalent structure to the uterus in male bodies? Or does it not start forming until later, after sexual differentiation has begun? Or does it vanish, like nipples in male mice? Are there many anatomical features that don't have an equivalent between men and women?

submitted by /u/raendrop
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The impact of canals in a city?

Posted: 21 Oct 2017 11:33 AM PDT

A lot of cities in The Netherlands have canals. Example

Once used mainly as a water highway for goods, now they're obviously less functional in that department. So other than aesthetics, what consequences/benefits does this have in a city?

Nature wise? Health wise? Temperature regulation? Etc..
Would there be a good reason for 'new' cities to incorporate canals/waterways like this in their design? (If costs wasn't an obvious limiting factor) Or is the impact of canals relatively low otherwise?

submitted by /u/AlbertLooper
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How do tree rings form?

Posted: 21 Oct 2017 08:29 AM PDT

Does a flashing LED light use less electricity than a steady light? Would a light on a 1/2 second on/off flash use half the electricity?

Posted: 21 Oct 2017 09:45 AM PDT

Can deaf people get tinnitus?

Posted: 21 Oct 2017 10:01 AM PDT

Do you burn more calories when cold compared to when you are warm when doing the same activity?

Posted: 21 Oct 2017 09:29 AM PDT

When sitting down for example, would my body use more energy and burn more calories in the cold than it would when I was warm or would there be minimal to no overall difference?

submitted by /u/ckoppula199
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What factors lead to the Wisconsin glaciation?

Posted: 21 Oct 2017 08:53 PM PDT

How do the switching mechanisms in transistors work, and how are they triggered?

Posted: 21 Oct 2017 08:55 AM PDT

I've been wondering for a while how the flow of electrons in a transistor was switched from one direction to the other. How does the software running on the OS interact with the hardware to manipulate the movement of electrons?

submitted by /u/afrench53198
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Why does absence of blood flow cause cell death?

Posted: 21 Oct 2017 08:41 PM PDT

Why don't the cells just stop working until blood flow full of nutrients and oxygen is restored (suspended animation if you will)?

submitted by /u/ravupadh
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Concerning the photoelectric effect, if an electron's energy is nearly proportional to the frequency of the incident photons, why don't solar panels work on cloudy days? Doesn't UV light, which is higher energy than visible and infrared, pass through clouds?

Posted: 21 Oct 2017 09:09 AM PDT

Or don't current solar panels currently work with UV light? And is there any progress towards engineering solar panels that can work efficiently in the UV range?

submitted by /u/arzthaus
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