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Questions tagged [biology]

Questions about biology are OFF TOPIC and should be asked on the Biology Stack Exchange. However, questions about biology in the context of physics (e.g., biophysics) can be on topic here if the primary concern is physics.

34 questions with no upvoted or accepted answers
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4
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1answer
83 views

What would the ideal amount of gravity be for an Olympic sprinter?

The goal here is to get the sprinter running as fast as possible. How much of an effect would more or less gravity have on the top speed of an Olympic sprinter, say... Usain Bolt? 6 ft 5 in (1.95m) ...
4
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0answers
219 views

Does Blue Light Really Have a Dark Side?

I was reading the following article on Wikipedia which discusses the dangers of blue light: Blue-light hazard is defined as the potential for a photochemical-induced retinal injury resulting from ...
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0answers
1k views

Why water heat capacity has minimum at body temperature?

Water heat capacity has the following plot: One can see it has minimum near 40 degrees of Celsius, i.e. close to human body and other warm blooded animals have. Is this just coincidence? UPDATE ...
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91 views

Stability of plants and buildings: the role of the xylem

Dicotyledon plants show a stem structure with many xylem tubes, hollow but with lignified (woody) walls. These are arranged as in the figure below, in a circle. Their roots, on the other hand, have ...
3
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0answers
106 views

Medical/Physics Question - Cut Off Finger Preservation

This question might require some knowledge of medical/tissue, but physicists seem to know everything, so figured I've give it a shot here ;) When people put cut off fingers they are told to put the ...
2
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0answers
1k views

Why human body is not affected on magnetic field?

Electric-current easily cause shock to human body. But magnetic fluxs through human body do-not cause any perceptible change, as-well no invisible-impacts/ health impacts are well-known. We, when hold-...
2
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1answer
62 views

Suffocation in a granular medium

I read of a recent accident in Alberta in which three girls fell into an open bed truck carrying canola seeds and suffocated. In that situation would it have been possible to keep breathing by using ...
2
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0answers
308 views

Insect Eyes Vs Human Eyes?

Humans have frontal eyes. Less field of view. But better resolving power. Insects have lateral eyes. This means they have a large field of view. In some female insects the lateral eyes have much more ...
2
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1answer
181 views

At what distance is lightning dangerous for someone lying down?

My 8 yo child told me that they learned at school that they should lay down flat on the ground in case of lightning. I told him that the more correct position is crouching down with feet together, but ...
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2answers
60 views

How does tanning oil increase UV skin damage?

I see many websites claiming oils amplify UV waves. This would only seem possible if thicknesses caused no reflection as in a quarter-wave coating, but that seems hard to believe. So, is it a myth ...
1
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1answer
48 views

If you get punched, is it better to be lighter or heavier?

I've seen people argue that lighter people can take a punch better because they can "go with it" better. This seems plausible to me, but is it really true? One reason why it seems plausible is that ...
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0answers
52 views

How much heat do we lose perspirating?

How can I calculate the heat my body loses from perspirating? For example, X Jouls per liter of sweat.
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32 views

Bimolecular and Isomerization reactions

Is it possible to describe a reaction of the $$ A+B \rightleftharpoons AB $$ exactly using the solution of an isomerization reaction? $$A \rightleftharpoons B$$ I just can not figure it out the ...
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121 views

Quantum beats and Quantum mechanical side of photosynthesis

I have two questions. One concerning quantum beats alone, another - process of photosynthesis. I am very well aware that there is strong evidence suggesting that mechanism that leads light through, ...
1
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1answer
100 views

What is the atomic composition of the human body, by volume?

According to Wikipedia, the composition (by atomic percent) of the human body is: 62% hydrogen 24% oxygen 12% carbon 1% nitrogen etc. Question: What is our volumetric composition*? *I get this is a ...
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105 views

Effects of light wavelength on the Hamiltonian of the FMO complex

Recently, I have been interested in the energy transfer within the FMO complex. I was wondering, how could the wavelength of the light that excites the complex affect the energy transfer efficiency. ...
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38 views

Audio anomaly identification

I left an audio recorder in the forest in many different locations for fauna identification. I am collecting subjects on my audio recorder that are clearly not in the frequency range of any animal ...
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0answers
128 views

Biological Themodynamics - What does an endpoint saturated signal mean. How does it relate to equillibrium constant

I have had a question that has been bugging me for a couple of years in my graduate school career, and I was wondering if perhaps some physicist could help explain it to me. Given an endpoint assay ...
1
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1answer
108 views

Properties of infrasound of our muscles?

I have read, that some animals (like cats) are able to hear other animals (like humans) staying still by percepting infrasound, emmited by their muscles. Is this true? I know, muscles are really ...
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41 views

Why don't we see/feel charged particles, penetrating our brains/retina?

If we see tracks in bubble or Wilson chamber, it means that particles are everywhere and can leave tracks in gases and liquids. They can also penetrate concrete of the building levels in the lab. So ...
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0answers
14 views

What are good books to study life sciences related physics at an introductory level?

I study medicine, but also love physics and I want to have this physical and mathematical perspective of what I learn. What are some good textbooks for studying physics for the life sciences (i.e ...
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23 views

Permeability of the human skull using Radio Frequency (RF) and Ultrasound waves

I have been looking into the permeability of the human skull using RF and ultrasound waves, and had a few questions. Which frequencies of Ultrasound and Radio Frequency (RF) waves can pass through ...
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0answers
31 views

The rise of BCI

If EEG and MEG are measuring different aspects of neural oscillations, why can't we measure the combined signals as a whole, when we are doing the same for higher frequencies? Why did the us navy ...
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0answers
131 views

How do hypermetropic people see objects beyond the focus of their convex corrective lenses?

The way I have developed intuition about optics suggests that humans can only see objects if two rays of light that originally emanated from the same point reach the eye in a way such that when ...
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0answers
54 views

Why animal eyes see the spectrum from red to violet?

Maybe this would not be proper question on physics stack exchange, but it originated from physics book so I'll post it here anyway. I have much interest in color recognition evolution. I'm studying ...
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2answers
63 views

What do we call these energy forms?

First of all I apologize for the basic question. When we throw a ball upwards, energy gets converted from us to kinetic energy which becomes potential energy and as the ball falls back down it ...
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215 views

Can a human body actually experience large gravitational time dilation?

As sometimes depicted in science fiction, can a human actually experience a large gravitational time dilation? These depictions often show a human experiencing a large dilation (ex. 1 minute = 10 ...
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1answer
239 views

Physics of Sound and the middle ear?

Once sound waves reach the eardrum, ,the eardrum moves back and forth and transmits those waves/pulses to three bones that serve to transmit and amplify the pulses to another "drum" in the inner ear. ...
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74 views

What material used in soil based microbial fuel?

I have seen from wikipedia that there are soil based microbial fuel which need only anode and cathode while soil itself could act as proton exchange filter But what kind of other material it needed? ...
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27 views

Hiccup in frequency domain

Main question: What would the Fourier transform of hiccup look like? This question is too general so let me elaborate a few possible approaches. Hiccup just as a series of pulses (of no matter what ...
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144 views

Magnification: Microscopes Telescopes

What is the difference between the way a microscope magnifies say a star and a telescope say a cell? Why is it, that the eyepiece of a telescope magnifies stronger when it is smaller and with a ...
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0answers
595 views

How does cryptochrome produce quantum entanglement?

I found this video on the net, which explains how a bird called "European robin" uses a trick based on quantum entanglement to see the earth's magnetic field. I am just asking if some of you know any ...
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2answers
75 views

Why do many animals die at the same time when lighting hits surroundings?

I have been reading about many cases in history of lighting striking and killing dozens even hundreds of animals, to be more specific quadruples, at the same time. Apparently this doesn't happen with ...
-1
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1answer
31 views

What is a safe mass flow rate

In my machine class, the instructor said that if we use compressed air to clean metal of ourselves then we'll actually get hurt because the pressure is too high. I am wondering, What is considered a ...