Cells Definition and 450 Threads

Hello everyone, I have a quick question. Ok the endoneurium is a layer of delicate connective tissue that encloses the myelin sheath of a nerve fiber within a fasciculus. Now my question is supporting cells of the nervous system like glial cells usually connect two nerve fibres together, so...

Homework Statement Two cells that divide on Earth each 10s start a travel to the Sun at v = 0.85c (Distance earth-sun: 1.5·10^11 m). How many cells should exist when the rocket they travel in carshes with the Sun? Homework Equations Time dilation: t=t0/sqrt[1-v2] being t0 the time from a...

I understand that space might be made up of individual units, such that you can't have a location which is between two units. When moving, a particle would just "pop" into the next unit repeatedly instead of smoothly moving - like how a computer screen works with pixels. Do I understand that at...

I'm not a biology students, so please use the simple language. The group of cells working in coordination for the same end is called a tissue. The combination of different tissues working in harmony together is called an organ. Different organs functioning according to some defined rules...

I have the following questions regarding solar panels. 1)Why solar panels which use sunlight concentrators gain in efficiency despite they produce larger currents?Usually it`s believed that with increase in current flow efficiency should fall. Example here is a fuel cells. 2)Currently...

Could somebody expain me the following questions: 1)Why hydrogen fuel cell needs catalyst (such as platinum) to operate, while elcectrochemical elements (such as zinc-air) do not? 2)Why power density increase in fuel cells leads to efficiency decrease while in electrochemical batteries it...

Homework Statement The maximum size to which a cell may grow is limited by the cell's ? Homework Equations NIL The Attempt at a Solution It's a multiple-choice question... so i picked nucleus. My argument is that the nucleus controls the internal functions of the cell. However...

Considering this is for a condensed matter course, I'm assuming it'll belong here :) I cannot, for the life of me, figure out why solar cells are operated in forward bias as that would counteract the electron-hole separation in the depletion zone. Wouldn't it make more sense to operate them...

I keep thinking of doing something with Solar Power. (Southern UK) The easiest, conceptually would be very basic homemade thermal panels but then there's the problem of how to use the hot (warm) water. That involves plumbing and a special hot tank. Once you've gone for that, you may as well...

Hi I just finished reading the chapter on electrochemistry from my chemistry textbook (I just took the first half of general college chemistry this past semester) and I feel like I’m missing something- I don’t understand how electric fields play into the operation of the battery. I understand...

I just read this article and began wondering if the woman hadn't died from cancer, would she have lived forever? http://en.wikipedia.org/wiki/HeLa

When I was reading back over my book to re-write my notes, I saw the words, "The Cl2 is the electrode (cathode). It must be in a solution with its ions i.e Cl- has KCL." My question is, why does the Chlorine gas have to be in a solution with its ions? If anyone could answer this, it would be...

Hi all, I recently made my own hydrogen fuel cell and really enjoyed the process and everything I learned. I didn't know much about electronics or cells, so it was a great learning experience. In my research I found that chemical engineers made a nanometal to work as a catalyst instead of the...

What exactly is the difference between a concentration cell and galvanic/voltaic cell? How do you know what are the half reactions? Also, is the ion and electron flow the same found in voltaic cells or is it the opposite? My biggest question of electrolysis has to do with Cl species...

Hello guys, A capillary is made up of a single layer of endothelial cells right. So when blood cells pass through it, do the endothelial cells take blood cells up by endocytosis and then release it to other side. How do capillaries take up nutrients, do the endothelial cells take it up...

This is my first post here, be gentle please ^_^. I searched for answers, but nothing came up. This is not homework, it's something I've been working on after I got bored with my Arduino. I'm working on a small project in my spare time. Using just discrete transistors, I'm building an adding...

1. The problem statement Given an n-dimensional CW complex on a space X, show that each n-cell is open in X. Definition of CW Complex 1. The cells form a disjoint union of X 2. For each k-cell e, there is a relative homeomorphism : \phi: (D^k, S^{k-1}) \rightarrow (e \cup X^{k-1}...

One way muscle grows is muscle hypertrophy where sarcoplasmic fluid increases inside the muscle cell. Wouldn't this burst the cell membrane, I can understand how organelles can replicate but what about the cell membrane. I know this sounds like a stupid question but please help. Thanks :smile:

Nerve and muscle tissue don't grow back much but epithelial cells in the skin grow very quickly. Why is that some tissues find it difficult to grow back and are replaced by fibrous scar tissue. Can't they do some mitosis and regrow? Thank you :smile:

The theoretical maximum efficiency of silicon solar cells is about 29%. How is this theoretical maximum efficiency derived? How can I use the working principles of a silicon solar cell to explain this?

So, I am doing a little bit of research on how energy is created in solar cells. From what I understand, there is just a whole bunch of n and p junctions connected to each other electrons flow the same way. Or, electrons travel one way, and holes travel the other. So when you dope the silicon...

What is your opinion of http://www.cbsnews.com/video/watch/?id=6228923n&tag=related;photovideo" segment which appeared on "60 Minutes today (February 21)? It would, if it proves out, apparently make the "fuel Cell" a feasible idea for mass use. KM

Hi guys, can you guys point to me what are the recent experimental results that show that cells can be induced to make a pluripotent cells?

Homework Statement How many cells can be in a computer`s main memory if each cell`s address can be represented by 2 hexadecimal digits? what if 4 hexadecimal digits are used? Homework Equations N/A The Attempt at a Solution ok, i tried and other people helped and i am stuck...

Hi, I was just doing some reading on semiconductors mostly with respect to photovoltaic cells. I understand that doping silicon with Boron and Phosphorus creates a good semiconductor because the extra electrons from the phosphorus jump over to the 'holes' provided by boron, and then creating...

From what i understand, the only thing that makes using fuel cells in cars versus lithium batties less desirable, is the cost of hydrogen. If hydrogen can be produced extremely cheaply, assuming the same standards for compressing and transporting and storage of hydrogen, would it be better...

Question given. Predict how the average life span of a nerve cell located in the brain differs from the average life span of a red blood cell. Provide a basis based on cellular features. I know that the average life span of a nerve cell is the life span of the organism which it lives in. The...

Does anyone know where I can get information on how particles such and quarks/lepton that form atoms, atoms to molecules and molecules to cellular life.? What area of physics is based on the area of study and can evolution of biological organism be traced?

A typical red blood cell subtends an angle of only 1.90E-5 rad when viewed at a person's near-point distance of 25.0 cm. Suppose a red blood cell is examined with a compound microscope in which the objective and eyepiece are separated by a distance of 12.5 cm. Given that the focal length of the...

This image confuses me a tad. We have the n-type (negative) silicon and the p-type (positive) silicon plates. We put the plates together. The electrons are in a rush to fill the positive "holes" on the p-side, and the positive holes are in a rush to to the n-side, to the electrons. Between...

Hello, Im working on a paper on solar cells and i came across the term "Fermi level". What exactly is the Fermi level in this context: "The working voltage produced by the device is the difference between the chemical potential of the titanium dioxide (Fermi level) and the redox...

Although a complete cost analysis is much more complicated, the particular question only requires the following: an energy cost estimate (in terms of $/Joule). This was directed to be done by taking volumetric or mass based costs of each fuel as well as the associated energy conent or energy...

How are plantae protists similar and different from plant cells? The Attempt at a Solution similarity: both are photosynthetic, and producers, both are paraphylitic differences: protists are unicellular whereas plants are multicellular, plants are big and complex where as protists are...

Homework Statement If the probability of any given molecule occupying any given phase cell is known, what additional information is required in order to work out the equilibrium distribution of molecular speeds in a pure gas? Homework Equations The Attempt at a Solution Since the phase...

Does anyone know or know where I could find the average mass of a single lymphocyte? Specifically, a T-cell?

Homework Statement 1.) Explain why it is necessary to divide phase space into quantified cells of a finite size. 2.) Why is it necessary to know the size of these cells to over come the Gibb's paradox? Homework Equations The Attempt at a Solution 1.) I think it's something to...

Hey all, This is just a post about some questions I had regarding electrolysis and fuel cells. I know that when electricity is forced through water the water molecules split, and produce hydrogen and oxygen gas. I was wondering how things like the electrode material and how far apart they are...

How are the cells (say 2V) of a typical lead acid battery connected in series to increase voltage to 12V when all the neg. plates are connected together and all the positive plates are connected together which as I understand is the principle of connecting two batteries in parallel (pos...

Here's something I've been wondering about for some time. How long does it take a cell to produce a string of amino acids? More spesific: The duration between the DNa beginning to make the RNA string and the string of amino acids being delivered?

Solar Voltaic Cells -- converting sunlight to electricity over a given area Homework Statement Lake Mead is formed by the Hoover Dam, and while it actually changes in area and volume, consider it has an average area of 100,000 acres. Assume that 250 W/m^2 of sunlight falls on Lake Mead...

How is the energy of an excited electron sent to another adjacent molecule as in the photosystem of chloroplasts in plant cells?

Given a multicellular organism, what is the theoretic minimum amount of cells it can have? Theory aside, what is the smallest known mulitcellular organism? Furthermore, anyone know of any links that show a table of organism and # of cells? Much thanks!

Homework Statement Using kirchhoff's laws, calculate the current in the 2 ohm resistor. Picture of the circuit attached. Homework Equations kirchhoff's laws, and ohms law The Attempt at a Solution i3 = i1 - i2 then i used kirchhoff's law to get: 2 - i1 = 2.i2 and 1 - 2 (...

I am doing the IB and have an extended essay to write. I intend to write it in Physics. I am thinking of doing something with my PEM fuel cell. However, I've found it hard to constrain the topic into the core of physics as fuel cell theory is mostly electrical chemistry. Any suggestions for a...

Im try to make sure i understand something right. I have two jars on the left is oxidation takes place and on right reduction takes place. A wire connects them to allow electrons to move. electrons move from left side to right side. This makes the left side negative cause it produces electrons...

What happens when virus invades a host cell, reproduces and then leaves without destroying the host cell. Then does the immune system destroy these infected host cells? How do viruses do damage. Is it simply by leaving the host cell and destroying it?If bacteria can enter the cell without...

Hello everyone, I just started biology and I have lots of clarifications If red blood cells are created in the bone marrow how do they enter the circulatory system. Do they permeate through the blood vessels?

Can anyone tell me how can I take the impedance spectra of a dye-sensitized solar cell ? Do I need to irradiate (i.e. AM 1.5, 100 mW/cm2) the solar cell during impedance measurement? or I can measure the spectra without irradiating light ? More specifically, how can I get the comparison between...

Homework Statement How exactly does connecting cells in series increase the voltage on the atomic scale? Does it speed up the electrons somehow? Explanations appreciated!

This question would perhaps be an ocean engineering question, but since we don't have a forum for that, I thought mechanical engineers would have some idea about this. My background is electrical engineering, and I have little knowledge about the mechanical issues when operating at the surface...