The biophysics tag has no wiki summary.
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What is the relationship between UV wavelength and penetration depth into human skin? [migrated]
Some background - Some recent research has strongly suggested that UVA penetration into the skin is far more dangerous than UVB, a very good example is this paper by Agar et al. (2004).
My query is, ...
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368 views
Google interview riddle and scaling arguments
I am puzzled by a riddle to which I have been told the answer and I have loads of difficulties to believe in the result.
The riddle goes as follows:
"imagine you are shrunk to the size of a coin ...
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Does gravitational force affect the human age? [closed]
I have a philosophical as well as a scientific question. The other day I was reading somewhere that under gravity a person ages faster,
i.e. when a person with a bad spine position gets affected more ...
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2answers
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Harmlessness of a pure alpha decay particle
From my high school physics class I remember that there are some particles which exhibit pure alpha decay (i.e. alpha decay to there stable isotope), like Po-210, Po-211 and Bi-209.
What I also know ...
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1answer
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Temperature gradient in body [closed]
Is there a Temperature gradient in the human body? especially I have heard that the eye is colder than other places? Is that right?
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Why can Hiroshima be inhabited when Chernobyl cannot?
In Hiroshima, atomic bomb was dropped, but today, there are residents in Hiroshima. However, in Chernobyl, there is no resident living today (or very few). What made the difference?
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1answer
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What is the minimum pressure difference for your ears to pop?
I'm assuming the answer to this largely varies from person to person. Assuming you could instantly change the pressure around your head by amount $\Delta p$, what is the minimum $\Delta p$ for your ...
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2answers
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Why can't Humans run any faster?
If you wanted to at least semi-realistically model the key components of Human running, what are the factors that determine the top running speed of an individual? The primary things to consider would ...
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1answer
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Atoms in our body
Our body of course exchanges some atoms with environment every day however are there some of atoms which stay with us a life time?
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Effects of a very large magnetic field on the human body
Ever since reading about the NHMFL I have always wondered about this and asked several people without getting a good satisfactory answer. My question is, considering the simplest case let's say a ...
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2answers
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Do viruses suffer from quantum de-localization?
Consider some microscopic life form. It should obviously be localized in space, in the quantum-mechanical sense, if it is treated as a single particle (though it is composite). If its characteristic ...
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RNA piece and force pulling it
RNA piece can be in two states, folded (energy E) or unfolded(enegry E1)? If you fix one side of the RNA, and pull on the other side with f that is constant... How will the force affect the energies ...
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Concentration of Proteins
You release a billion protein molecules at position $x = 0$ in the middle of a narrow capillary test
tube. The molecules’ diffusion constant is $10^{−6} \ cm^2 s^{−1}$. An electric field pulls ...
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1answer
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Radiation exposure to a child who was briefly in the presence of an adult who had received a 18FDG PET scan
I am a physician who thought she was good at math, but apparently am not as I cannot figure out this mathematical/physics question. (My background is obviously NOT nuclear medicine!) A family friend ...
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1answer
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Measuring life through radiation
Dramatic title, I know. But it's shorter than Measuring a person's effective mass through radiation and comparing it to their weighed mass and I figured this would get people's attention.
I just ...
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Recommended (bio)polymer physics book? [closed]
I am looking for a recommended introductory book on polymer physics.
I do not have sufficient time to learn the whole field. I am specifically interested in physics of biological polymers, and even ...
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2answers
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Was the early Earth radioactive?
I've been reading of the (surprising) fact we are uncertain on whether there is nuclear fission in the center of the Earth or not (yet we know so much detail on structures at the other end of the ...
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2answers
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Computing microstate probabilities based on Boltzmann distribution for chemical systems - Is it rigorous?
One approach to predicting the folded structure of a polymer (DNA, RNA, protein) is to compute the probability that any particular part of the polymer $x_i$ is "paired" with another part of the ...
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How efficient is the human body?
This question sort of comes to mind when hearing how efficient an internal combustion engine is turning chemical energy in mechanical energy (something like 20-40%) with lots of excess heat. As an ...
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2answers
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How neutrinos can be harmful?
What are the circumstances in which neutrinos can harm humans or even kill them.?
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Octave equivalence: biological or more?
I'm a graduate student in mathematics doing a bit of research in signal processing and Fourier analysis and I've come across a question that could probably be better answered by a physicist:
Is the ...
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0answers
79 views
How can I measure the calories consumed in daily activity? [closed]
From a nice question here:
How are the calories in food calculated?
I can roughly understand how people provide the data of calories in certain food.
However, I am still confused about 2 things.
1) ...
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3answers
355 views
Why does light of high frequency appear violet?
When people are asked to match monchromatic violet light with an additive mix of basic colours, they (paradoxically) mix in red. In fact, the CIE 1931 color space chromaticity diagram shows this ...
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1answer
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What is the difference between “in-plane shear modulus” and “shear modulus”
In the wiki it is article only about shear modulus and it is written that it's unit is Pascal.
At the same time in all researches about Red Blood Cells shear stresses, authors write "in-plane shear ...
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1answer
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How is tritium illumination possible without negative health effects?
Turns out there's tritium illumination - a tiny very strong plastic tube will be covered in phosphor and filled with tritium. Tritium will undergo beta decay and a flow of electrons will cause the ...
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Climbing stairs two at a time vs. one at a time. Which one is more efficient? [closed]
What is the more efficient way to climb stairs? Taking two steps at a time is almost twice faster, but how much energy does it take compared to taking one step at a time?
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2answers
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How much time can I power my laptop by eating one dessert?
Random question that popped into my mind after a 4-hours power outage. Let us assume that I am eating an extra dessert (250 kcal) and that I am using a bike and a generator to power my laptop (it ...
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Visualise the sound intensity
I'm studying Biophysics and my current subject is sound. One of the properties of sound is intensity. From my notes I can see the following definition:
Intensity Formula is: $(I = w*m^{-2})$ or $(I = ...
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1answer
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What is physics of a normal jump?
What is the physics behind a normal human jump ?
when a normal human wants to jump.
First, some energy is stored in their thighs and The elastic tendons Just like a spring.
In mechanics and ...
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1answer
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Why do beverages taste different based on how cold they are? [closed]
Why does temperature effect the taste of beverages?
Specifically, how does the temperature for example mask certain tastes ie filtered vs unfiltered water taste very similar at colder temp and Is ...
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1answer
132 views
How do photo mosaic work from eye and image processing perspective? [closed]
Hello fellow investigators
I have two question about optical illusions
1) A photo mosaic is something like this http://i.stack.imgur.com/Pzplp.png
What are the optical principles behind our eye ...
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How and where is the information which constitutes memories stored in our brain? [closed]
I am wondering if the information was stored as in computers, with a sort of condensators system, but this would imply a certain discretization, and seems to be too restrictive.
Therefore, how the ...
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2answers
161 views
Can wireless power transfer harm organic life by anyway?
Now, humanity can beam 50-60 watts power through 10 centimeter-thick concrete block. Can such wireless power transfer harm us by anyways?
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Is metabolic rate the amount of heat given off?
The Basal Metabolic Rate is intuitively expressed as "the amount of energy you consume just sitting around." In some places it seems to be equated with the amount of heat that you give off.
Is this ...
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Dynamic Light Scattering
In the Dynamic Light Scattering experiment, how is the intensity distribution plotted against time, keeping in view the multiple scattering of photon particles in laser ?
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Cyclist's electrical tingling under power lines
It's been happening to me for years. I finally decided to ask users who are better with "practical physics" when I was told that my experience – that I am going to describe momentarily – prove that I ...
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1answer
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Examples of piecewise smooth dynamical systems [closed]
I have recently been studying continuous dynamical systems whose phase space can be divided into a number of regions. Inside each of these the flow is smooth, but there is a discrete jump in the flow ...
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3answers
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Why is the sky not purple?
I realise the question of why this sky is blue is considered reasonably often here, one way or another. You can take that knowledge as given. What I'm wondering is, given that the spectrum of ...
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Why don't massive water-borne animals crush under their own weight when they're in water?
If you take a giant whale out of the water and put it on land for long enough, it will crush itself under its own weight. Why doesn't the animal get crushed under its own weight when it's in water?
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Human perception of distance
When we see things around us, distant objects look smaller to our eyes than nearby objects do.
Is there any physics-related reason why our eyes or brain perceive things like this?
Or if this is ...
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2answers
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Why the pressure of atmosphere doesn't crush you when you e.g. walk outside?
Why the pressure of atmosphere doesn't crush you when you e.g. walk outside? I mean the density of air is $1.26 kg/m^3$, so with $100 km$ above us, it exerts much pressure on you when you walk ...
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Is energy applied by the muscle when it holds a body in the air? [duplicate]
Possible Duplicate:
Why does holding something up cost energy while no work is being done?
We all know the following Newtonian formulas:
PotentialGravitationEnergy=m*g*h
Kinetic Energy = ...
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2answers
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How can an an ant lift 50 times its own weight and pull 30 times its weight?
According to many sites like this one, an ant can apparently lift 50 times its own weight and pull 30 times its weight. Is it true?
Can it be proved using physics? Though most sites agree that an ...
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How Safe Are Heat Ray Guns?
Could a little meddling with the frequencies of the Heat Ray Gun beam result in frying crowds rather than dispersing them?
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1answer
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How does a stronger magnet affect the MRI image quality?
In which ways is a stronger magnet better for magnetic resonance imaging? I read that:
The field strength of the magnet will influence the quality of the MR image regarding chemical shift ...
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1answer
365 views
How does a speaker produced different sounds?
What I have read is that a speaker produce sound by just moving a coil attached to a cone which moves back and forth. So, If I try to move the coil by hand, would it produce sound? If not why not? or ...
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What does Peter Parkers formula represent?
Okay, so the trailer for the new Spider Man movie is out and appearently our friendly physicist from the neightborhood came up with something. However I can't find out what this is.
...
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2answers
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How does space affect the human body (no space suit, no space craft)
How does "outer space" affect the human body? Some movies show it as the body exploding, imploding or even freezing solid.
I know space is essentially a vacuum with 0 pressure and the dispersion of ...
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What are brain waves? [closed]
I watched a documentary showing that humans could alter the results of an experiment by thinking about it, and the data these people collected supported their hypothesis.
And the reason these people ...
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What happens to body chemistry at the speed of light?
Assume that I'm traveling at the speed of light in one direction. My brain is also traveling at the speed of light in that direction. Presumably there is at least one receptor site in my brain that is ...
