What is Structure: Definition and 1000 Discussions

A structure is an arrangement and organization of interrelated elements in a material object or system, or the object or system so organized. Material structures include man-made objects such as buildings and machines and natural objects such as biological organisms, minerals and chemicals. Abstract structures include data structures in computer science and musical form. Types of structure include a hierarchy (a cascade of one-to-many relationships), a network featuring many-to-many links, or a lattice featuring connections between components that are neighbors in space.

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  1. T

    What Are the Possible Changes in the Fine Structure Constant in the Past?

    Scientists are doing experiments to find any change in the Fine Structure constant in the past. It is dependent on the following constants. C (Velocity of Light) e (Charge of the electron) E0 (Permittivity of free space) h (plancks constant) Could you pls let me know which of the...
  2. O

    Why do we need Gamma point in Band structure

    First post,a good begin. As far as I know,the band gap is generated from the bragg reflection at the BZ boundary.So I think we just need the special K-point at the surface of 1BZ,and also the band gap(direct or indirect) is at the special K-point on the surface. But it seems not real in most...
  3. M

    Photonic Band Structure Calculation

    I am trying to calculate a photonic crystal’s band structure for a very simply case of a 1-dimentional periodic medium, or rather I am trying to understand the calculations that I am looking at for this situation. The end result of what I would like to do is get some function that I can graph...
  4. P

    What is the structure of the electron?

    I ve got a small question. As I have learned so far, the electron is a particle with negative charge and it is homogenouus, i mean there's no concept of structure inside an electron. But electrons have spin .. so they must have certain structure ?
  5. P

    Which Structure Has The Highest Melting Point?

    Which structure will have the highest melting point?
  6. M

    Can MO Theory Explain the Electronic Structure of C60?

    Ok, i am investigating the electronic structure of fullerenes through Near edge x-ray absorption spectroscopy and I really need to know the connection between hybridization theory and LCAO. Everywhere I look it says the carbon atoms in C60 are sp2 hybridized ( sp3 due to angle strain), but as I...
  7. D

    Chemistry Lewis Structure of These Molecules?

    I need to write the lewis structures of two ionic compounds. Can anyone help me out? Thank you. 1) (NH4)2SO3 2) LiBH4
  8. G

    What is the minimum force T necessary to lift the wheel?

    Hi I'm very new so I'm not sure if this is the best place to put this in. I've got a problem that I'm having trouble working out and any help would be great. 'A retracting nose wheel assembly is raised by the application of a torque T applied to link BC through a shaft at B. The wheel and arm...
  9. Amith2006

    Fine structure of sodium spectrum

    Homework Statement Estimate the strength of magnetic field produced by the electron’s orbital motion which results in the 2 sodium lines(5890 & 5896 Angstrom). Homework Equations The Attempt at a Solution Let E be the potential energy of a magnetic dipole when placed in an...
  10. B

    Universal Structure - Bubble Theory

    From general research, I have seen a certain pattern emerge that causes me to re-evaluate how I look at the universe. It's easier to see with visuals, but I will try to describe it here. I believe some of the abstractions can lead to a better understanding of the structure of the universe, or at...
  11. S

    How Does Substitution in NiTi Lattice Affect Transformation Temperatures?

    Hello, I was curious as to what you think of the paper below. This concerns the effects of substitution in a NiTi lattice on the transformation temperatures. The author seems to draw from this study, that since Nickel has comparatively localized electrons, the increase in temperature...
  12. L

    Combining Fine Structure Corrections

    Homework Statement We are to combine the Relativistic Kinetic Energy, Spin-Orbit Interaction, and Darwin fine structure correction terms into a single formula for the energy shift in the Hydrogen atom. The formula must depend only on j = l +/- 1/2, but not l, and must be valid for all l...
  13. Helios

    Equation for Solid Planet Structure

    I'm looking for an radial equation to find the pressure or density of the interior of a moon or rock planet. It would involve Young's modulus or Poisson's ratio or something like. Any help?
  14. C

    Dumb question about electronic structure

    I want to ask which type of the following would have a greater repulsion electrons with parallel spin, electrons with opposite spin. or it's just the same?
  15. I

    High energy electron scattering and proof of nucleus structure

    Hey all, I am currently revising for my Physics mock but i can't get my head around high energy electron scattering, and the proof this provides for the size of the nucleus. I have read from a variety of texts and some of the links on here but these have lead me to become even more...
  16. S

    Alternative theory of gravity explains large structure formation without dark matter

    When i read "Alternative" i immediately thought "crackpots!", but then I read on and found out they're on to interesting stuff. http://www.physorg.com/news85310822.html
  17. K

    Explaining the structure of Galaxy Filaments

    Explaining the structure of Galaxy "Filaments" Are galaxy filaments something that could be explained by the Big Bang theory, but NOT the steady state theory? What makes the scale of galaxies so special that the forms which are generated are unlike what happens in nebulas? Is the expansion...
  18. E

    The Fine Structure Constant and Hawking Radiation

    Abstract. Theory of quantum gravity is still a mystery, as well as the derivation of fine structure constant and masses of elementary particles. (Fine structure constant is calculated from force between two elementary charges.) Possibility that elementary particles are black holes is offering...
  19. H

    Creating a material structure which only allows heat in one direction.

    Hey everyone, i've been a lurker here for a while now but i was wondering if the combined mind of the physics forum could help me come up with a few more solutions to this problem. I'm looking into creating a low cost composite material which would absord solar energy during the day and...
  20. Loren Booda

    Does a quantum possess structure or geometry?

    Does a quantum possesses structure or geometry? If so, how would one describe it? Does a quantum intrinsically counteract definition in spacetime?
  21. M

    Titanium 2+ Ion electronic structure?

    Titanium 2+ Ion. Is it [Ar]3d^04s^2 or [Ar]3d^24s^0 I'd assume it's the former (looks more energy efficient).
  22. B

    So the top quark is pure mass, with no internal structure, as heavy as a gold nuclei?

    The gold nucleus has an atomic mass of 197 with 79 protons and 118N and 79 electrons. The top quark has about the same mass, but no internal structure. It's just a particle with pure mass. Why would a structure of pure mass and nothing internal decay?
  23. K

    Forming Structures from Cells: Exploring Bone Cell Replication

    I've only taken high school biology and I'm actually a computer science major, but I've had an idea rolling around in my head recently and I think it might be better realized if I approach the problem from a biological standpoint. I'm sort of stuck at a particular problem that I can't seem to...
  24. 0

    Are There Standard Tools for Verifying Directory Structure?

    Are there standard tools for verifying that a directory structure takes a certain form? This is for when a program needs certain minimum files with certain name constraints to be in certain places and directories with certain name constraints to be in certain places. It would specify things...
  25. U

    IF3 Lewis Structure Guide: Mastering the Bonding Pairs & Electron Counting

    Trying to draw Lewis structure for IF3. There's four atoms, so 32 electrons needed minus the 28 availabe (7 valence each) give 4 electron bonded pairs, which is 2 bonds... but there has to be at least 3. I'm stupid, what am I missing? edit: never mind i got it
  26. H

    Help Needed: Determining Rhodamine B Band Structure Experimentally

    Hi, my name is Hans Lindroth and I have difficulties understanding how to determine the band structure of a chemical substance (in this case rhodamine B) experimentally, given I have the absorption spectrum of it. Is there anybody out there who can help me with this? If you can please help...
  27. A

    Chemistry Features in the molecular structure of a compound that affect solubility mp,bp.

    Hi guys, I need some help with this question. What features in the molecular structure of a compound affect its solubility and its melting and boiling points. I need to answer this question with several examples and include structural diagrams. Please help :yuck:
  28. S

    Help with structural formula and resonance structure

    I don't know what I am doing wrong, please help. 2) How many different structual formulas can be written for C6H14 Include straight chain and branched chain compounds. Enter an integer as an answer. (I put in 5 but it say that I am wrong) 3) Which of the following...
  29. J

    Exploring Electronic Structure: What Are Bands?

    hi, I am beginning study electronic structure and I do not understand formely what is a band, what mean the lines that appear when a band structure calculation is made?, where are the bands?. thanks
  30. N

    Chemistry Ques. re: structure of organic compounds

    Okay, using the structure of organic compounds. Are supposed "natural" vitamin C extracts from rose hips better than synthetic tablets of vitamin C? I have to answer this and if another source is used document it. So If you have the answer can you tell me where you found it? Thanks in advance...
  31. B

    PDF example of mechanical structure?

    Where can I find a good course (maybe in pdf) that give me a lot of example of mechanical structure? Statical, dynamical? Thanks.
  32. P

    Cartan forms and structure equations

    Could someone explain these two concepts? What I need is the big picture of 'why' we need this, roughly 'what' these equations mean, 'where' its used etc Thanks in advance
  33. C

    Talk on the group structure of elementary particles

    The Background: I'm looking to put together a 40 minute talk on the group structure of elementary particles for a group of undergraduate mathematics students many of whom know little about group theory - sort of a math talk with a physics flavor (no pun intended). So the talk would include...
  34. L

    Band structure and dispersion relations

    -Let's suppose we have 2 gases ..one is a "Fermi" gas under an Harmonic potential and the other is a "Bose" gas under another Harmonic potential... in both cases (as an approximation) the particles (bosons and electrons are Non-interacting) then we could write the partition functions. \prod...
  35. marcus

    New value for alpha, the fine structure constant

    alpha reciprocal new value is 137.035 999 710(96) (uncertainty 0.70 ppb) http://physicsweb.org/articles/news/10/8/1/1?rss=2.0 "The new value, based on the most precise measurements ever of the magnetic moment of the electron, has an uncertainty of 0.7 parts per billion. The new value is ten...
  36. M

    Structure constants of Lie algebra

    The following matrices are written in Matlab codes form. The standard basis for so(3) is: L1 = [0 0 0; 0 0 -1; 0 1 0], L2 = [0 0 1; 0 0 0; -1 0 0], L3 = [0 -1 0; 1 0 0; 0 0 0]. Since [L1, L2] = L3, the structure constants of this Lie algebra are C(12, 1) = C(12, 2) = 0, C(12, 3) = 1...
  37. M

    Structure constants of Lie algebra

    The following matrices are written in Matlab codes form. The standard basis for so(3) is: L1 = [0 0 0; 0 0 -1; 0 1 0], L2 = [0 0 1; 0 0 0; -1 0 0], L3 = [0 -1 0; 1 0 0; 0 0 0]. Since [L1, L2] = L3, the structure constants of this Lie algebra are C(12, 1) = C(12, 2) = 0, C(12, 3) = 1...
  38. R

    Nuclear Structure: Hindrance Factor Explained

    What is hindrance factor? What does it indicate? If the Hindrance is very high? If its low? For eg. 103Rh (39.76 keV) E3 transition has got hindrance factor of ~400. What does this mean. The Hindrance is calculated using Theoretical Lambda(E3) / Exptl. Lambda (E3) Lambda(E3) -- >...
  39. P

    Mathematica Mathematical structure of terrorism

    I wonder if they can tell if this means the war is lost, or if they will be able to defeat the insurgents by manipulating this 'law of terrorism'.
  40. R

    Suitable Nuclear Book explaining Structure Functions

    I have just completed my undergraduate degree and results pending will be starting a PHD in nuclear physics. However in my undergrad nuclear physics i found my recommended textbook Introductory Nuclear Physics by Kennith Krane and my lecture notes weren't the greatest for explaining about...
  41. N

    Structure of the Milkyway Spiral Redifined

    Astronomers have made the most detailed map ever of our galaxy's overall shape, showing that its spiral arms extend much further than expected. Evan Levine, Leo Blitz and Carl Heiles of the University of California at Berkeley analysed the distribution of atomic hydrogen in the Milky Way at...
  42. R

    Strength In Relation To Bone Structure.

    I realize this is related to biology, but I think the question would be better suited to those who study or have studied physics. The question is this: I learned recently that the cavity in bones, actually increases the overall strength of the bone, even though it has less mass than if it were...
  43. B

    Exploring the Unknown: CO2-V Network Solid

    Well, we know how quartz and glass are a network SiO2 molecules *But what if we replace the Si atoms with carbon? In other words, what if we have the same network arrangement of CO2 molecules? -Is there a name for this network solid? Edit: Perhaps I am referring to "CO2-V", possibly?
  44. R

    Cartan's first structure equation proof

    this is my first post on this site but it looks like the sort of ppl that i would like to associate myself with. Unfourtanately, I have not had any formal schooling for any mathematics above calculus but i have read a few books and papers and am trying to make due. I was studying about the...
  45. R

    Lewis Structure Help: CH3NCO Bonding Scheme

    i am attempting to figure out the lewis structure/ bonding scheme for CH3NCO. so far i have: O=C=C-N-H l l H H the Hs are attached to the second C then the N the formal charges seem to be ok i have a formal charge of 0 for O...
  46. K

    Band structure of ferromagnetic metal

    for a ferromagnetic metal, the there will be splitting of energy band(one for spin up e- and one for spin down e-) under the influence of external magnetic field. the it is known as exchange splitting. here are my questions 1. what determine the degree of splitting? i guess it depends on the...
  47. H

    Can you help with Electron Dot Structures for these 6 compounds?

    I got another problem with my Chemistry Homework. I need to put the Electron Dot Structure for the following. 1) Lead Oxide 2) Potassium Sulphide 3) Sodium Nitride 4) Silver Oxide 5) Copper Chloride 6) Calcium Chloride Hope somone can help
  48. H

    Structure of Liquids: Atom Arrangement & Phase Diagrams

    What is the structure of the liquids??isn't there any way by which we can differentiate between structure of liquids...And above all what is that "thing" present between individual atoms in liquid state? All these questions arose while studying phase diagrams...because we had FCC,BCC(etc.) for...
  49. J

    Egg White Protein Structure Change

    Hey, I have some homework questions and I'd appreciate some clarification. As a class we did an experiment where we put egg white into seven different test tubes, and then introduced seven different solutions, one to each test tube. The different solutions were weak & strong salt solutions...
  50. G

    Group theory and crystal structure

    Hi, I have the following problem : I generate GaAs (zinc blende structure) supercells, and then I want to replace some As atoms by N atoms. Let's say I have fcc conventional cell repeated twice in the x, y and z direction so that I have a total of 64 atoms, 32 of Ga and 32 of As. 8 atoms...
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