The use of methods from the physical sciences to aid in the study of biological systems.

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Criteria for electrophysiological threshold

As opposed to action potential thresholds (which are yes/no events), electrophysiological thresholds of compound action potentials are arbitrary. Mostly a certain noise level is picked and when the ...
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71 views

How do diving marine mammals avoid decompression sickness?

How do marine mammals, whose very survival depends on regular diving, manage to avoid decompression sickness or "the bends?" Do they, indeed, avoid it?
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69 views

How do marine mammals control buoyancy?

Presumably, as a whale or seal dives, its lungs get compressed by the increasing water pressure, and it gets less buoyant. Under this model, for a given amount of air taken in at the surface, the ...
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68 views

effect of pupil responses on the electroretinogram

The electroretinogram is generally considered to reflect the retinal processing of a light stimulus, typically a photoreceptor response followed by secondary neuronal activity. However, I am wondering ...
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1answer
51 views

How non-invasive blood glucose concentration measurement work?

Diabetes patients need to conduct the “fingerstick” a few times a day. One of the mechanisms of "fingerstick" is to take small amount of blood sample and put it onto a test strip. The enzyme on the ...
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1answer
37 views

How non-invasive blood glucose concentration measurement work? [duplicate]

Diabetes patients need to conduct the “fingerstick” a few times a day. One of the mechanisms of "fingerstick" is to take small amount of blood sample and put it onto a test strip. The enzyme on the ...
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1answer
59 views

What is the difference between rheobase and threshold?

Neuronal tissues can be excited by electrical stimulation. Two commonly encountered characteristics for electrically stimulating nerve cells is the threshold and the rheobase. My question is what the ...
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2answers
48 views

Problems understanding membrane potential

I understand that membrane potential is the difference of the extracellular and intracellular ionic charges, due to their concentrations. We say that the extracellular space has a charge of 0 and then ...
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19 views

Unexpected stoichiometry n in ITC experiments

I'm looking at the binding of a small molecule to several RNA constructs and tried to determine the binding constants. To do this I've performed a few ITC experiments on this system, the results were ...
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1answer
70 views

How efficient is the human body at metabolizing food?

My friend and I were having a discussion over how "efficient" human digestion is. If a human ate a 1000 calorie hamburger, how many of those calories (how much energy) does the body process into ...
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1answer
45 views

How to measure the total number of cells in an average human body?

I have got one assignment to calculate the approximate sum total of all cells in the human body. How to tackle this problem? I know that the current statistics is $10^{13}$ cells. I wanted some hints. ...
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1answer
66 views

How to estimate the DNA density in human sperm head? [closed]

I have got an estimate of sperm head volume from internet.Like consider it as a disk of order 4-5µm. Now I wanted to find the DNA density in the sperm head. How to find that?
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34 views

What is the biding site code recognized by the parts of the spliceosome

Another question about another Youtube video. At 0:50, the splicing process begins to remove the non-coding section of the DNA (intron), so the different parts of the spliceosome attach to the borders ...
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47 views

What regulates the timing of the motion of molecular machines during DNA Replication?

This question is about this video I found on Youtube. I just want to know what is the mechanism which regulates the timing of motion of the parts of these molecular machines. I know that those big ...
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1answer
44 views

How Ants know about Earthquake?

How does an ant know about Earthquake is it because of an organ or due to other factors?
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29 views

Kinesin-5 / cytoplasmic dynein spatial density distribution in neurons

is there some way to experimentally determine the density distribution of those two molecular motors in a Neuron? Fluorescence labeling would be impossible(?) as GFP markers would probably alter the ...
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2answers
50 views

Useful physical information of a protein

Beside energy and heat, I don't know any useful physical information of a protein. Can you help me list some of it. Somethings like Fourier-transform infrared spectroscopy to provide protein structure ...
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1answer
32 views

Muscle force/energy relationship

I found the Hill muscle model, which helps relate the force a muscle can generate to its change in length over time (its "contraction velocity"). Is there a similar model to get an idea of the energy ...
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53 views

PQR files make from pdb2pqr are different to GROMACS

I have a pdb file and I would like to make a pqr one. In GROMACS, I use editconf -mead to produce pqr, with topol.top taken from pdb2gmx or use it to produce pdb file, then use pdb2pqr. Which one is ...
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78 views

How to determine whether the energy of a stem-loop fold is significant or not?

If I have a predicted RNA stem-loop of energy -0.30 kcal/mol, and another of -4.9 kcal/mol, how do I tell whether such a structure is a significantly stable structure or not? Our two competing ...
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2answers
57 views

Which types of hydrogen bonds are known to exist in RNA secondary structures?

I'm programming an implementation of an algorithm for pattern matching in RNA structures. The algorithm assumes the following types of base pairs: Plain: No base pairs (just the primary structure of ...
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1answer
32 views

Protein Conformation Modeling

I'm interested in learning about computational modeling in biophysics. I have heard some amount about people modeling proteins as a network of ideal springs to examine things like conformation ...
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1answer
26 views

Nervous System : Signal Translation

If a device were created to monitor the nervous signals from the heart, including stable heartbeats, rapid heartbeats, etc., and this device were capable of transmitting the "stable heartbeat" to the ...
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1answer
38 views

What's the best way to measure/calculate the size of a light beam at the sample of a microscope?

I am using a microscope with an LED derived light through the epi-fluorescent port of a microscope. I know that the "field of view" for a given objective is equal to the field number/magnification ...
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1answer
53 views

Do local field potentials (LFP) create waves on the surfaces of nerve cells?

Are waves created by the LFP on the surfaces of neurons cell bodies? Since the cells have a resting potential, do these waves create harmonic oscillation of the membranes at particular frequencies? ...
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181 views

How is membrane capacitance related to the increased speed of saltatory conduction?

Here is the original question which inspired my question. As explained by the answers there, the reason saltatory conduction in myelinated neurons is faster than non-myelinated conduction is because ...
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4answers
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How do trees lift water higher than 10 meters?

The atmosphere pressure is 10 meters of water (approx). This means that it is impossible to lift water higher than 10 meters with vacuum or сapillary action (on Earth, under normal conditions). There ...
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1answer
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Isotropy of sarcomere bands in skeletal muscle cells

As seen under a polarization microscope, the A-Band in skeletal muscle fibres is so named because it is anisotropic in its refractive index which is a characteristic of orderly crystalline structure. ...
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How is saltatory conduction faster than conduction of unmyelinated fibers? [duplicate]

It's always the same explanation that currents are able to "hop" along Ranvier nodes instead of passing continuously along the axon making saltatory conduction more efficient than continuous ...
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1answer
58 views

What is the strength of human cornea?

What is the difference of pressure a human eyeball cornea (cornea, lens and other elements separating vitreous body from air) can handle? Or asking differently: what the outside pressure should be to ...
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69 views

Harmful effects of radiation from cell phone towers? [closed]

As per this article - http://www.thehindu.com/news/national/mumbai-citizens-link-cancer-to-cell-phone-towers/article5139166.ece , people living adjacent to cell phone towers claim to have developed ...
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391 views

How do small animals make loud sounds?

Walking past the park today, I heard a cicada so loud I thought at first it must be some sort of large power tool. How is it that that very small animals like cicadas (crickets, etc.) can make such ...
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Do voltage-gated calcium channels in earthworms relate to speed of neuron conduction?

We have a hypothesis that a drug may block the voltage-gated calcium channels (VGCC) in annelid worms. We are wondering whether there are any correlations between VGCCs and neuron conduction ...
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1answer
776 views

What is the exact principle of capillary isotachophoresis?

I know it's a type of capillary electrophoresis, but I don't get how does the separation happen exactly.
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430 views

What is the relationship between UV wavelength and penetration depth into human skin?

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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Why is saltatory conduction faster than continuous conduction?

How does spacing apart sodium and potassium channels allow the action potential to travel faster down the axon? This is the reason always cited for saltatory conduction and myelination, but my mental ...
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4answers
331 views

Does darker skin color make it easier to live under sun?

I have always thought darker colors absorb more heat from the sun, so if you are wearing a white T-shirt you will be cooler under sun than wearing a darker T-shirt, or a black piece of steel will be ...
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1answer
157 views

What is the energy balance of cooking?

If I cook some food, I get apparently several energetic advantages: thermal : the temperature of the food is closer or superior to the temperature of my body or internal organs, so I do not have to ...
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1answer
305 views

Why human cannot stand still in one place?

When a human stands in one place, he cannot stand still but we can see the body slightly swings. Is this due to the Earth rotation or it has something with biology and muscles relaxations? I have ...
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225 views

Question about equilibrium potential formula

My biology book says, that the equilibrium potential for an ion with a charge of +1 is: $$E_{ion}= 62mV \biggl(\log\frac{[ion]_{outside}}{[ion]_{inside}}\biggr)$$ Where does the 62 mV come from? How ...
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1answer
968 views

Does coloring affect the perception of depth?

I have a question about the mechanics of human vision which may be as much of a physics question as it is a biology/physiology question. I noticed that if I try to imagine a clear blue daytime sky ...
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3answers
4k views

How do warm-blooded animals keep their temperatures constant?

Warm blooded animals like us keep their temperature constant irrespective of their surroundings. But how do they do that? Energy should be supplied from the inside. I assume that reactions like making ...
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3answers
396 views

What is a good list of unsolved protein structures?

I'm trying to get a list of unique soluble structured proteins that don't have a solved structure. That is, they aren't the usual membrane proteins or some derivative of another protein. Things that ...
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3answers
200 views

Action Potential Distribution On Synapses

This is a biology+physics question. Since there is no biology section, I am asking here. In brain, when a neuron reaches to threshold value, it fires an action potential. In most graphics, that is ...
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2answers
767 views

Bone conduction . Different from the normal hearing phenomena in humans?

Bone conduction, is it something different from the normal phenomena of listening through the ears. I checked on some literature . Is it so that Bone conduction has very less to do with the ears and ...
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2answers
4k views

How do trees use Adhesion and Cohesion to move water against gravity?

I have an AP Bio class where I have to name 3 properties of water and I chose adhesion and cohesion for one of them. I'm having trouble finding out how exactly trees use adhesion and cohesion to move ...
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1answer
102 views

How to quantitatively measure work done by a biological system?

Thermodynamic efficiency can be expressed as the ratio of Work done(W) to Energy invested (Q). Thermodynamic efficiency= W/Q How can one measure work done by a ...
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2answers
902 views

Is the EC50 of an activating protein for an enzyme a good indicator for the binding affinity Kd?

We work with a membrane protein system where measuring the affinity between the enzyme and the upstream activating protein has been difficult, and when measured in detergent solution, it is almost 100 ...
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195 views

How do optical illusions work? [closed]

Hello fellow investigators I have two questions 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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1answer
242 views

Are Bovine serum albumin, Avidin, Ficoll-70 and Dextran-70 positively charged or negatively charged? [closed]

Bovine serum albumin, Avidin, Ficoll-70 and Dextran-70,are they positively charged or negatively charged ? And which other solvents can be used as a substitute to water for preparing solutions in each ...