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22

Dickinson (2005) has a good review of insect flight, including behavior, biomechanics, electrophysiology, and neural control with links to more of the primary literature. What follows is a general summary thereof. The jagged trajectories you mention are called saccades in the insect flight literature. In Drosophila, saccades are ~90° turns accomplished in ...


17

Usually in biology (and being ATP, it most probably is biology), it's one of two things. The gamma-phosphate (the third one, the one farthest from the adenosine) is very unstable, meaning the phosphoanhydride bond is easy to break. The cell "allows" it to break, but only at the cost of moving the phosphate to some other molecule, such as a serine or ...


14

Although at first sight this might seem to be biology rather than physics, maintenance of human posture is an example of control theory. Indeed a quick Google will find many publications on it - I found a good review here. A standing human is a dynamical system that is not in equilibrium so it requires a (closed loop) feedback system to maintain it. This ...


12

Absolutely a serious part of research - quantum mechanics defines chemical structure and reactivity. Whenever you see a headline like 'Scientists find quantum effects important in protein activity, weird huh?', read it as 'Scientists find pragmatic classical approximations inadequate in describing protein activity'. In protein structure, for example, ...


9

You can certainly get massive differences between EC50 and affinity. This is especially true for cell-based assays and membrane protein systems. The reason why is because the appropriate time scales to achieve binding equilibrium (hrs for nM affinity, days for picomolar, feptomolar affinity according to back of the envelope calculations) may be and likely ...


8

That quasi-travesty is the Nernst equation in $\log_{10}$ for a positive monovalent ion at physiological temperatures (37 degrees celsius), but they've hidden all that from you. Shame on them. The canonical form of the Nernst equation, for an ion $S$ is $$ E_{S} = \frac{RT}{z_{S}F}\ln{\frac{[S]_{out}}{[S]_{in}}} $$ where $R$ is the gas constant, $T$ is ...


7

No; the problem is, as you pointed out, that no organism will manage to multiply, grow or even sustain itself without absorbing matter to create new cells and fill metabolic losses. Even photoautotrophic organisms which get energy from light (which is in fact an E-M wave, so pretty close to electricity) collect matter from the environment -- plants for ...


7

Quick search - Some articles that may interest you: 1) Random walk model of insect movements Kareiva P. M., Shigesada N. (1983). Analyzing insect movement as a correlated random walk. Oecologia 56(2-3) 234-238 2) Artificial life model of flying insects and its comparison to real insects navigation strategies. Dale K., Collett T. C. (2001). Using ...


7

There are two factors that need to be taken into account here: 1. Myelination decreases membrance capacitance. The rate at which sodium influx through a node can depolarize the axon at the next node is related to both the current and capacitance across the membrane (in addition to a few other factors). So while adding a new node to the axon would indeed ...


7

Disclaimer: This is not my field of research. First, this is not a complete answer to our question. A nice explanation of the current hypothesis of water transport in trees (Dixon-Joly cohesion-tension theory, originally proposed 1894) can be found at The Amazing Physics of Water in Trees but also in Tyree (1997). The key points are that the stoma (leaf ...


6

The System intracellular/membrane/extracellular space is well described by the model of a Concentration cell (see more on Wikipedia). The equation you mentioned is also called the Nernst equation. $$ E_{ion}= 62mV \biggl(\log\frac{[ion]_{outside}}{[ion]_{inside}}\biggr)= \frac{k_B T}{z e} \biggl(\ln\frac{[ion]_{outside}}{[ion]_{inside}}\biggr) $$ where ...


6

It isn't about heat but ultraviolet light. Melanin is the pigment that makes our skin colour whatever it is and in darker skin there's more melanin. Melanin dissipates UV, which otherwise would cause skin cancer as it introduces mutations into DNA. Melanin production is stimulated by UV so that's why tanning beds work, our body senses the danger and responds ...


6

if you are using NMR structures you might be making the mistake of using several superimposed structures - it would be nice to develop with x-ray structures at less than 2.0 A resolution for starters. Some of the models at low resolution can be sloppy, but submitted after 1994 or so will not have any center to center distances as that's when the x-ray ...


5

In high school, we did an experiment that showed this. Basically, if you take a glass of water, and let it sit out, perhaps in front of an open window, it will eventually lose water due to evaporation. It may take a few days/weeks to really see a large difference, but the level will go down. But, if you take a few flexible straws, put them in so the bendy ...


5

This phenomenon is called depolarization block and it occurs in real membranes in current-clamp experiments. The key mechanism is that the membrane has not been allowed to repolarize sufficiently to relieve the inactivation of sodium channels. The Hodgkin-Huxley model reflects this in the "inverted" voltage-dependence of the h gate (sodium inactivation ...


5

Solar UV radiation is broadly classified as UV- A,B and C (Decreasing order of wavelengths). Penetrating ability of UV is a not a direct function of its wavelength; lesser the wavelength lesser is the penetrating ability (But higher is the energy: a direct function of wavelength). Penetration ability is dependent on scattering and absorption. Most ...


4

(I probably ought to have a pat answer to this on the tip of my mind, but since I don't I'm going to wing it. This is probably just an opportunity to make an utter fool of myself. Please treat everything that follows with extreme suspicion.) I think this is effectively an artefact of the model. That may not be true in the strictest sense -- it is possible ...


4

If I cook some food, I get apparently several energetic advantages... Let's make things a little more explicit. If you are talking of energy within the body, you are talking proteins, alcohols, fats, and sugars. You are not talking Vitamins or Minerals or any of the unique compounds (like specific antioxidants) that are available in the food. ...


4

Since there seems to be several distinct sub-topics in your question, I will answer them one-by-one: 1). There are a variety of mechanisms that allow endothermic animals to maintain thermal homeostasis in a cold environment. The main ones are: a). The shivering response: When the core body temperature of a endotherm drops below a critical value (36.8C in ...


4

I think you are really wondering how axonal morphology affects the voltage along the axon. The short answer to your question is that each synaptic terminal sees the same voltage because that voltage is generated "fresh" at each site. This has nothing to do with synaptic strength, which determines the amount of voltage deflection in the postsynaptic terminal ...


4

While Luke's answer is perfectly correct, the answer can be given in a more intuitive manner. First, the main point is that it is increased positive voltage (inside the axon) that opens the sodium ion channels to propagate the action potential. The question is: how fast can this voltage get to the sodium channels? In an unmyelinated axon, the movement of ...


3

Yes, color and shading can certainly affect depth perception, as explained by wikipedia: Aerial perspective – Due to light scattering by the atmosphere, objects that are a great distance away have lower luminance contrast and lower color saturation. Due to this, images seem blurry the farther they are away from a person's point of view. In computer ...


3

I am not sure that kind of action would be a "significant influence", but the general understanding is that LFP and spike frequency are inter-correlated (1, 2). An interesting recent publication on the topic (3), however, doubts this correlation as the nature of LFP recording and signal processing might introduce some artifacts to the recordings. It would ...


3

Measuring the work done by a biological system seems pretty impossible. Imagine how many different ways one cell of your body uses energy (ATP). You can't really measure all the work done by every cell on a macro scale. Metabolic efficiency has been defined as... "health". That seems just a little ambiguous. That's why we use things like averages to ...


3

Prologue: Bone conducted signals are considered to be evoked by the perilymph fluid moving back and forth out of the cerebrospinal cavity, via the cochlear aqueduct, towards the scala tympani. And not by mechanical deformation of the cochlea. “the fact that the bone conduction phenomenon is actually the result of the push-pull movement of the perilymph fluid ...


3

Measuring the electrical signals (=nerve signals) from the heart is frequently done in medicine, it is called electrocardiography. It looks like this (from the same article): Influencing the heartbear can also be done and is done by pacemakers. Depending on the patients necessities the can permanently stimulate the heart or do this only, when certain ...


2

Sound travels faster through solid material than air. It also travels more efficiently, the sound does not diminish as quickly over long distances as the molecules in the air do not collide as often and can cause the sound waves to decompose over time and distance. This is accentuated when the solid through which the sound is travelling is long in one ...


2

For charge, you could check this one by sequence level, for example for Bovine Albumin (Uniprot: P02769) you can get the theoretical pI of 5.82, as the mean of pKa aminoacid values, to do this can use protparm, so when the pH > pI, the protein has a net negative charge and when the pH < pI, the protein has a net positive charge. And there are only two ...


2

Try looking at structure homology databases - the sequences that they have no annotation for are likely the kind of sequences that you are seeking. SUPERFAMILY has a comprehensive annotation across almost 2500 fully sequenced cellular genomes. this would be a good place to start ...


2

This is how I would do it: Download the UniProt/SWISSPROT flat file for bacteria from here. After decompressing the files, extract the E. coli protein IDs for which there is no PDB annotation in the file (I am giving you a command line that will work on *ix systems (Linux/Unix/OSX etc)): zcat uniprot_sprot_bacteria.dat.gz | gawk ...



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