Structure Definition and 1000 Threads

What does it mean to give a group structure? I'm working on a problem and part of it asks for the structure of the group. The law of composition and generators seem to be given already (and an expression that says that a^2 = 1 for any elt a of the group). Is there anything to do other than...

What would be the consequences of slightly changing the fine structure constant, i.e. changing the strength of the electromagnetic interaction - but not changing gravitation or the strong force? In the everyday world? You might imagine that the strength of chemical forces etc. would change...

Everytime I see a picture of the large scale structure of space with matter arranged in a web like form, I come to think of the fenomenon of viscous fingering in fluids between to surfaces when they are moved apart. Since space is expanding as well, maybee these structures have something to do...

There is observational evidence for preferred alignment of spiral galaxies with alignment to the so called axis of evil in the CMB (cosmic microwave backgound 2.75K) data. http://arxiv.org/ftp/arxiv/papers/0707/0707.3793.pdf http://arxiv.org/ftp/arxiv/papers/1104/1104.2815.pdf

Hello experts! Q#1) Write down the family members of {110} plane in a cubic crystal. Attempted Answer) According to my study the this family has 6 members. But what are they? Are these the members (110),(101),(011),(-1-10),(-10-1),(0-1-1)? Q#2) Describe the method to construct the...

Homework Statement Using the pin-jointed structure in the image: a) Set up ALL equations of equilibrium for the structure. b) Determine ALL reactive forces within the structure, including the directions and locations where they act. I have attempted the problem however i can't seem to find a...

Hello! I am a student and have just started studying about graphene. However I am having quite a lot of problems understanding the crystal structure, specifically, I am unable to place certain terms. These being : 1. Basis vectors.(I do understand what a basis vector...

Changes in the internal structure during a "Topological transform" Is there any field of topology which deals with the changes in internal structure of an object when it undergoes topological transform? If I'm transforming a cube into a sphere, is there any 'field of topology' which analyze the...

For a given volume, what (regular) geometrical shape would yield a maximum surface area of a flat-bottomed structure (ie, building for example)? IH

Phi ~ 1.618

I am facing the following interesting question. A closed room\hall contains several identical machines in it, they are fed by an electrical cable. The machines can be turned on or off. When a machine is turned on, it consumes electrical energy and as a by product generates heat. The heat...

I am curious to know if anyone can shed some light on a question I have concerning the neutrino. I am referring only to the electron neutrino and not the others that have theoretical mass values. If it has not mass or charge does that mean it has no dimensions? Or because it has no mass can...

Hello I want to know the available methods to change the 3d structure of a molecule Thanks

Transisiton metal electronic structure question. :) Hey guys, basically I know that Chromium and Copper "donate" one of their electrons from the 4s sub-shell to the 3d sub-shell. Is this true for ALL transition metals? Any help would be greatly appreciated. :)

Electronic Structure question? :) Hey guys essentially in my GCSE Chem class we were told that the maximum number of electrons that can be held in the first four shells are as follows - 2,8,8,2. Now in my AS Level textbook it is saying that it goes 2,8,18,32. Can someone please explain to me...

Hi everyone! I find my way here on google frequently when I get some idea and want an answer, but I haven't been able to find any answers to a few questions I have. I hold no formal knowledge of astronomy or physics, so be understanding if my questions seem inane. I always find answers to my...

OK, the Dirac delta function has the following properties: \int_{ - \infty }^{ + \infty } {\delta (x - {x_0})dx} = 1 and \int_{ - \infty }^{ + \infty } {f({x_1})\delta ({x_1} - {x_0})d{x_1}} = f({x_0}) which is a convolution integral. Then if f({x_1}) = \delta (x - {x_1}) we get...

Hi all, I have a rather naive question about the fine structure constant and the relationship between its value and the energy scale involved. I understand the idea of the a charge being 'screened' by vacuum polarization (i.e., electron-position pairs popping in and out of existence), and...

I and a few friends thought about the oort cloud... If it has 2 light years in lenght, that's half way to Alpha Centauri... What would stop our near neighbor Alpha Centauri to have its own oort cloud... And if this is wright couldn't the galaxy be filled with dwarf planets, asteroids and...

Can anyone tell me what structure would support more weight? And why? Assume all lines are suppose to be straight.

the product of velocity of an electron and the principal quantum number is independent of which variable ? options given : a) velocity b) principal quantum number c) speed of revolution d ) energy of electron I wrote c, is it correct ?

typedef struct { char firstname[MAXLEN]; char lastname[MAXLEN]; char color[MAXLEN]; char baseball[MAXLEN]; char skiing[MAXLEN]; char tree[MAXLEN]; int zipcode; } student_t; So this is a user defined structure that is supposed to store data about a person. It stores the first...

Hi folks, I'm hoping to get your opinions about something. If i were given two linear equations and needed to solve for x and y using the methods of "substitution" and "elimination", what algebraic structure should i use? I can solve the systems just fine, but I'm trying to "explain" each step...

Hi all, structure factor is 2πi(hx+ky+lz), (hkl)is plane index, and (xyz) is index within a unit cell of real lattice. For example, we are now calculating FCC's structure factor. In general, textbook taught us using convention unit cell of FCC( that is FCC in form of cubic) to index...

I have read an amount of material on (potential) variations in the Fine Structure Constant. The majority of the material seems cautiously positive in declaring support for the potential variations, but I have a couple of question that you may be able to help me with. 1) Am I correct is...

Hi all, I have a question about perturbation theory and the fine structure constant. Consider an electron moving through the vacuum - this wil induce vacuum polarization, and (if I understand correctly) perturbation theory can be used to analyze the situation. My question is essentially: if...

In crystalline material, bands arise due to the interaction of electron waves with periodic potentials. Can anyone please explain the origin of energy bands in non-crystalline material..couldn't find relevant links on Google.

Hi all, I have a bit of a variation of a question I asked some time ago. Webb et al. continue to publish results which suggest that the fine structure constant may vary over space and time. I realize the results are controversial - what I'm wondering: If the fine structure constant...

I was attempting this question where I had to say which, out of graphite, diamond and sodium chloride represent a giant molecular structure? The answer is only the first two. Why is the latter excluded?

[FONT="Times New Roman"]I need to derive the lattice parameter in terms of the Zn-S separation distance, l. I looked up the value and I've found it to be a = \frac{4}{\sqrt{3}}l The way that I started my derivation was saying that each tetrahedron has a sulfide ion in the center, so then we...

Let $H\leq G$, where $G$ is some infinite group, and there exists some $g\in G$ such that the set $\{g^n: n\in\mathbb{Z}\}$ is a transversal for $G/H$. Then is $H$ normal in $G$? I suspect not. However, I cannot seem to find a counter-example. (By "a transversal for $G/H$" I mean that 1)...

I came across this question in chapter 4 of Hull 'Options Futures and other Derivatives'. I have the answer but I am not sure what the explanation is. Could anyone help? The term structure of interest rates is upward sloping. Put the following in order of magnitude : a) the 5 year zero...

I am building a little balsa wood model. I was hoping there was a program to help me test designs before I spend hours gluing sticks together. I've used a 2d program for testing bridge designs, but I've never seen a 3d version. I'm hoping this question is cake walk for you guys. Also, I...

Hello, I graduated in spring 2010, and I am beginning study for the Oct 2012 FE / EIT exam (long wait, I know ...) . I was wondering if anyone else has taken it after being out of school about two years, and what you did to efficiently structure / make use of your time for studying for...

Hi Everyone, I have a question about panel vs. solid rod structures. Assume a two cubes of equal dimension and weight. Cube 1 is made of panels, ie. a hollow cube. Cube 2 is made with solid rod Material is linear elastic Which would be stiffer? I think the panel...

[FONT="Times New Roman"][SIZE="3"] It is well known that, "Neil bohr failed in his model in which he described an electron as a charged particle moving in well defined circular orbits about the nucleus." However he failed because of the two major reasons.. a) It didn't consider the wave nature...

Hi all, just like the atomic world is unobservable to our normal optical observation, can it not be that there can be out there some structure too large that we are deluded to believe that there are merely galaxies and all empty beyond.

Hello, I have a quick question about extension fields. We know that if E is an extension field of F and if we have got an irreducible polynomial p(x) in F[x] with a root u in E, then we can construct F(u) which is the smallest subfield of E containing F and u. This by defining a homomorphism...

Hi, this is my first post on this forum and I hope that I am in the right category. My question concerns an independent study and not a homework assignment. However, it's a standard homework question in introductory solid state physics courses which makes me both the more frustrated that I...

i'm considering whether to take chemical engineering or material engineering to major. anyone can help to explain the topics and scope of both of these engineering?

The question is to draw the shear and moment diagram for this frame structure. I think I can do the diagram part alright, but I'm confused as to how I can draw the FBDs for this structure. What I'm thinking is to split into two members, AB and BC. For member AB, I know that there's...

I don't understand the fibre bundle structure of the Mobius band, described by my textbook. "The base space ##X## is a circle obtained from a line segment L as indicated in Fig. by identifying its ends. The fibre ##Y## is a line segment. The bundle ##B## is obtained from the product ##L \times...

Cai Easson avoid "eternal inflation", use Higgs to seed structure Cai and Easson's paper takes off from the seminal paper of Shaposhnikov and Wetterich that is discussed here at BTSM https://www.physicsforums.com/showthread.php?t=560031 Shapo-Wetter predicted 126 GeV Higgs in 2009 on the...

when i see 3d images of the webbed shaped structure of the universe, such as clusters and strands, the strands meeting in superclusters, i can't get away from how identical this looks to a reduced dimension view of the upwelling of water after a wave crashes. the foam from the ocean, which you...

I am hoping someone might be able to explain the significance of the arrows in the following structural diagram of copper(II) phthalocyanine (CuPc). http://upload.wikimedia.org/wikipedia/commons/e/ec/Copper_phthalocyanine.svg Which I have also seen represented as dashed lines such as on...

Ok I've been surfing trough the internet for quite some time now trying to find a solution to my problem but nothing similair pops up. This is my problem: http://i40.tinypic.com/295dc9f.png For some peculiar reason the structure tends to bend over to the left. I have no idea why and I've...

Dear forum people, I just learned how to get a tight-binding dispersion for graphene: E = +- \sqrt{1+4\cos((\sqrt{3}a/2) k_x)\cos((a/2) k_y)+4\cos^2((a/2) k_y)} But i can not figure out how can I plot that. I want to plot that in the following path: K \rightarrow \Gamma \rightarrow M...

guys can u help me how ta make a structure in DEV C++ ? the all information i need thanks guys :)

I've been having a very difficult time understanding why band structure is expressed in terms of momentum/crystalline directions. I've included a picture of the band structure of silicon so that you can better understand my question. I think I understand basic crystalline structures and the...

I am not a chemist. I have a molecular structure question. Is it possible to bind two positively charged molecules together by having two electrons bounce up and down in the space between them? M1+ e e M2+ imagine the e, electrons oscillating up and down. Either in sync and 180...