What is Elements: Definition and 1000 Discussions

Éléments is a French bi-monthly magazine launched in September 1973 and associated with the Nouvelle Droite.
With a social and European inspiration, the magazine promotes a critical vision of liberal modernity on topics such as localism, ecology, respect for cultural diversity and the defence of European identity.

View More On Wikipedia.org
Recent contents Top users
  1. T

    Hamiltonian matrix off diagonal elements?

    I'm trying to understand how Hamiltonian matrices are built for optical applications. In the excerpts below, from the book "Optically polarized atoms: understanding light-atom interaction", what I don't understand is: Why are the \mu B parts not diagonal? If the Hamiltonian is \vec{\mu} \cdot...
  2. ajayguhan

    Why Does Sum of Matrix Elements x Cofactor in Different Rows Equal Zero?

    In a matrix the sum of element of a matrix in a row times it's co factor of that elemt gives the determinant value, but why does the sum of element of a matrix times cofactor of different row is always zero?
  3. P

    How to understand the off-diagonal elements

    In quantum mechanics, observable variables are represented by operators, and thus can be replaced by matrix in a certain basis. If we have H|n>=E(n)|n>, where |n> are eigenfunctions of Hamilton matrix. Here is the problem: what's the physical meaning of <m|P|n>, namely off-diagonal elements of...
  4. 1

    A set equality proof without elements, I broke my brain?

    Homework Statement b(B) = cls(B) \ Int(B) where b(B) is the boundary, cls is the closure, and int is the interior of set B. This was not hard for me to prove by picking elements and showing that the sets were contained in one another. However, I decided it would be fun to try to derive it by...
  5. S

    Induction to prove then number of subsets with elements of 3

    Homework Statement Prove that a set with n elements has \frac{n(n-1)(n-2)}{6} subsets containing exactly three elements whenever n is an integer greater than or equal to 3. Our professor wants us to use Induction. Homework Equations P(n) = \frac{n(n-1)(n-2)}{6} n \geq 3 The...
  6. Hunus

    Euclid's Elements - The Application of Areas

    In Heath's commentary on Euclid's Elements he stresses the importance of the application of areas (Book I Proposition 44) with, "The marvellous ingenuity of the solution is indeed worth of the 'godlike men of old'...". The proposition, "To a given straight line to apply, in a given...
  7. D

    Finding the elements of a group given two generators and relations

    Hey everyone Let's say I have two generators, a and b, with the following relations: a^{5}=b^{2}=E bab^{-1}=a^{-1}; Where E is the Identity element. What I've done so far is this - the number of elements of the group is the product of the exponents of both generators, which is 10...
  8. M

    Counting Elements in Sets: Steps Included

    How many elements does each of these sets have where a and b are distinct elements? (with steps please) a) P({a,b{a,b}})b)P({∅,a,{a},{{a}}}) c)P(P(∅)) *i have tried to solve them but i am a little bit confused... Thanks in advance :)
  9. E

    Making Heavy Elements: Can Plutonium Be Made Naturally?

    Hi there, I understood that heavy elements could only be formed in stars or supernovae explosions. However I have just read that plutonium can be made by firing deuterons at uranium. Now uranium is a smaller atom than plutonium so what it going on? It seems to me that heavy elements can be...
  10. L

    Sample & Hold in SPICE not holding charge using real elements

    Hi guys, I'm having problem in HSPICE. I designed a Sample & Hold circuit using MOSFET switches (transmission gate). The problem is that when I activate the MOSFET switches, the capacitor doesn't hold the charge as expected (I did the simulation using ideal components, and the charge holds...
  11. E

    How to Calculate Classical Orbital Elements Using Matlab?

    Hi! Is there a way to calculate the classical orbital elements for a satellite or space shuttle around Earth using Matlab? I would like to get started with it since it is something that I've not tried before. so plese help Best regards
  12. M

    Which elements of the human body are found elsewhere?

    Carbon (18%) Hydrogen (10%) Nitrogen (3%) Calcium (1.5%) Phosphorus (1.0%) Potassium (0.35%) Sulfur (0.25%) Sodium (0.15%) Magnesium (0.05%) Copper, Zinc, Selenium, Molybdenum, Fluorine, Chlorine, Iodine, Manganese, Cobalt, Iron (0.70%) Lithium, Strontium, Aluminum, Silicon, Lead...
  13. J

    Algorithm to find the submatrix with the greatest sum of its elements?

    This is a challenge problem I thought of: Given a real-valued matrix A, develop an algorithm that finds the submatrix with the greatest sum of its element. (If there's a tie, just return an arbitrary submatrix that's tied for the win.) Is there a way other than brute force?
  14. M

    Aberrations at Lens Elements as Unsharp Filter

    I want to learn do aberrations and compensation actions used as unsharp filter for final image ? I read a Leica paper. There was symmetrical lens Summicron as a subject. I found that at the exit of the lens there were no aberrations without corrected. But when you look inside , some lens...
  15. M

    Filter Near-Zero Matrix Elements: Reasonable?

    Given A(m,n), eps = Machine Epsilon, fNorm = FrobeniusNorm(A), p >= 1 To filter noise near zero created by floating point error: if (|Aij| < fNorm * eps *p) Aij =0 end if Seem reasonable?
  16. D

    Power absorbed by multiple elements

    Homework Statement Calculate the power absorbed at t=0,t=0+,and t=200 mS by each of the elements in the circuit of fig 11.25 if us is equal to (a) -10u(-t) V (b) 20 + 5u(-t) V Homework Equations The Attempt at a Solution...
  17. B

    Why the off-diagonal elements of electric dipole element are zero?

    the two energy level atom, whose hamiltonian takes the form \hat{H_A}=E_g|g\rangle\langle g|+E_e|e\rangle\langle e|, where E_g as well as E_e represent the eigenvalues and |g\rangle as well as |e\rangle denote the ground state and excited state. There is an interaction between the atom...
  18. S

    Accelerating Atomic Decay Rate of Unstable Elements

    Is there any thing that could, or any way to increase the atomic decay rate of already unstable elements, such as the radio active elements. magnetically or otherwise, even if the thought is only plausible or otherwise theory, I wouldn't mind hearing it. A thought accord to me, what if...
  19. L

    Invertible elements in a commutative ring with no zero divisors

    Homework Statement Suppose that a commutative ring R, with a unit, has no zero divisors. Does that necessarily imply that every nonzero element of R is invertible? Homework Equations The Attempt at a Solution We have to show that there exists some b in R such that ab = e. Having...
  20. tom.stoer

    List of matrix elements or Feynman diagrams

    Is there a list of matrix elements for elementary processes? ##f\bar{f}\to\gamma\to f^\prime\bar{f}^\prime## ##f\bar{f}\to Z^0\to f^\prime\bar{f}^\prime## ##ff^\prime\to W \to \ldots## ##qq^\prime\to \ldots## ##\ldots##
  21. C

    # elements in base does not depend on the basis

    Essentially, I have to show that where {e_1,...,e_n} forms the basis of L, no family of vectors {e'_1 ,..., e'_m} with m>n can serve as the basis of L. The book shows this by saying there exists a 0 vector such that 0 = \sum_{i=1}^{m}x_ie'_i, where not all x_i vanish. I wanted to show it by...
  22. Einj

    Pseudoscalar Matrix Elements and Parity Transformation Behavior

    Hi all. I have a question. What is the behaviour of the polarization vector of a pseudoscalar particle under a parity transformation?? Let me explain my problem. I know for sure that the effective matrix element which links a D^* and a \pi can be written as: $$ \langle \pi(p)D^*(q,\lambda)...
  23. J

    Why are there still heavy elements in the earth's crust?

    When the early Earth melted, the heavy elements were drawn to the center due to gravity. Thus we have a iron core. Why shouldn't the core also have drawn in the heavy elements like uranium? The theory says the heat energy for the melt was due to the radioactive decay Why do we still have a...
  24. W

    Proof Writing for Dummies: Intersection & Union Elements

    Problem: Prove that any element in the intersection of two sets is also in their union. I am reading a proof writing book for dummies & the solution given in text is: http://tinypic.com/r/141hn7/5 http://tinypic.com/r/141hn7/5 First Question: In exam/test, is it OK if I write the...
  25. S

    How have supernovae shaped the evolution of heavy elements in the Milky Way?

    Hi, I'm new here. Can someone help me with several sets of questions? I know the estimated age of the Milky Way. There is information that there are various types of supernovae in the Milky Way that occur on the average of 2.2 to 2.7 per century. My first set of question: Is this...
  26. S

    Outer valence electrons for d-block elements (Se to Zn)

    I wish to better understand the configuration situation for the outer most valence electrons for the d-block elements, Sc to Zn. I am having a problem understanding how to predict where the two outer most valence electrons must be located for some of the ten d-block elements? For some...
  27. Y

    Looking for image theory regarding magnetic elements.

    Question on Perfect Magnetic conductor. Are PMC always metal compound like Iron etc. That has high ##\mu##? So most of good magnetic conductor are themselves electric conductor? From articles I read: PEC ##\Rightarrow\;\hat n \times \vec E=0\;\hbox{ and }\;\hat n\times \vec H=\vec J##...
  28. ash64449

    Explaining weird trend of d- and f- block elements.

    Hello friends, I noticed from Wikipedia the following information: Atomic radii: 4th period(only d-block elements): Sc:160 pm Ti : 140 pm V : 135 pm...
  29. B

    Does constantly removing elements from a set produce the null set?

    If you keep removing elements from a nonempty set, will you eventually get the null set? Some context below in a problem which I made myself and have been trying to solve: A set S having property P is smallest with respect to property P if S is an improper subset of any set having property P...
  30. E

    Superposition, Moving Around CKT Elements

    2. V=IR, Voltage division, KCL, KVL 3. When I short out the dependent current source by replacing it with an open, can I switch the location of the independent source and the 20 ohm resistor so I can do a voltage division to find the voltage across the 20ohm resistor which is then equal to Vo...
  31. A

    Orders of elements in a quotient group.

    Homework Statement I want to find the orders of the elements in Z_8/(Z_4 \times Z_4), (Z_4 \times Z_2)/(Z_2 \times Z_2), and D_8/(Z_2 \times Z_2). Homework Equations The Attempt at a Solution The elements of Z_2 \times Z_2 are (0,0), (1,0), (0,1), (1,1), and the elements of Z_8 are of course...
  32. B

    Uniqueness of identity elements for rectangular matrices

    Let A be the set of n \times n matrices. Then the identity element of this set under matrix multiplication is the identity matrix and it is unique. The proof follows from the monoidal properties of multiplication of square matrices. But if the matrix is not square, the left and right...
  33. E

    Calculating on-axis elements of a solenoid

    I wanted to mention that this solenoid has many winds over many layers. The thickness of the windings is 2.4 inches coming off of the engineering schematics, and has many many many turns, which is unknown. It has a 6T field at the zeroth point on-axis. I'm doing research with a professor and...
  34. J

    Relationship between the number of fuel elements and criticality

    I usually do not ask for this kind of stuff, but this time I really have no way to verify if this is correct(and it has to be). So here it goes: On a subcritical nuclear reactor with 100 fuel elements we read the signal of 10e-9 A. When we add 10 more fuel elements, signal jumps to 10e-8 A. How...
  35. C

    Do I need a new book? (Using Calculus: The elements by Comenetz)

    Hello all, I am re-teaching myself calculus (I don't remember anything from Calculus in college, and I only took calc I in college) I am using the book stated in the title. I got up to page 65...so far so good. Until it started asking me to compute definite integrals. Nowhere so far...
  36. W

    Eigenvalue problem with operators as matrix elements

    Hello, I have a feeling that the solution to this question is going to be incredibly obvious, so my apologies if this turns out to be really dumb. How do I solve the following eigenvalue problem: \begin{bmatrix} \partial_x^2 + \mu + u(x) & u(x)^2 \\ \bar{u(x)}^2 & \partial_x^2 + \mu +...
  37. C

    What elements a light made of?

    What elements? How a light beam became a light? Thanks in advanced.
  38. B

    Permutations with Repetition and Repeated Elements

    The theory says that if you have x objects containing a repeats of one element and b repeats of another, Np(without repetition)=x!/(a!b!). If you have x objects and repetitions are allowed, Np(with repetition)=xx, correct? Combining these, if we have x objects containing a repeats of one...
  39. H

    Can a Passive Device Mimic V = (const.) d3I/dt3 in a Circuit?

    The three circuit elements are capacitors, resistors, and inductors, which act in the following manner: Capacitor: V = (1/C) q Resistor: V = R dq/dt Inductor: V = L d2q/dt2 Is it possible to build a passive device that acts like: V = (const.) d3q/dt3 Google search has come up with...
  40. Fernando Revilla

    MHB Zach's question at Yahoo Answers (Field with 25 elements)

    Here is the question: Here is a link to the question: Abstract Linear Algebra? - Yahoo! Answers I have posted a link there to this topic so the OP can find my response.
  41. B

    Difficult Stats Problem (Repeated Elements)

    Homework Statement A word has n letters, in which one of those letters is present a times and another is present b times (all other letters are present only once). a.) How many combinations of x letters are there from this word? b.) How many arrangements of x letters are there from this word...
  42. A

    Order of Elements in a Group: A Quick Check of Understanding

    I just want to check if there is anything wrong with my understanding... Let's say we have a group of order 42 that contains Z_6. Since the group of units of Z_6 has order (3-1)(2-1), it means that we have 2 elements of order 6 in G, right? In other words, for any cyclic subgroup of order n...
  43. A

    MHB Order of product of elements in a group

    Hello. I'm just beginning my course in algebra. I've been reading Milne, Group Theory ( http://www.jmilne.org/math/CourseNotes/GT310.pdf page 29). I've found there a very nice proof of the fact that given two elements in a finite group, we cannot really say very much about their product's...
  44. X

    Algorithm or expression to put n elements in k sets

    I have 17 elements, and I want to put them in 3 sets. This makes 2 sets with 6 elements, and 1 set with 5 elements. Now I want to find an algorithm to partition n elements in k sets. Can anyone give me an algorithm, or a math expression for me to implement in a algorithm? Thanks
  45. T

    6 Nodes, 4 Elements, Size of Stiffness Matrix?

    Howdy, If I have the following configuration of nodes: 2---4--6 | \ | /| | \ | / | | \| / | | \/ | 1---3--5 What should the dimensions of my FEM stiffness be? Thanks
  46. R

    Showing elements of a Principal Ideal Domain are Relatively Prime?

    Homework Statement Let ##R## be a PID and let ##\pi\in{R}## be an irreducible element. If ##B\in{R}## and ##\pi\not{|}B##, prove ##\pi## and ##B## are relatively prime. Homework Equations ##\pi## being irreducible means for any ##a,b\in{R}## such that ##ab=\pi##, one of #a# and #b# must be a...
  47. F

    Why do different elements have different charges?

    Since I was first introduced to chemistry, it's been because "it has two more than eight, and it wants eight to be "happy" so it loses two electrons and gains a positive two charge." It's good enough for me to write on tests, but 'happy' isn't exactly a scientifically accurate term. And why...
  48. N

    Convert between state vectors and orbital elements

    Hi there I've been struggling to convert the following two vectors into orbital elements, the vectors are as follows: R = 0i - 7950j + 0k km V = 5i + 0j + 5k km/sec I would like someone to help with the calculations of the following COEs: - semimajor axis (a) - eccentricity vector...
  49. J

    Projection of surface area elements in vector calculus

    Homework Statement (i) Find the normal, n, at a general point on the surface S1 given by; x2+y2+z = 1 and z > 0. (ii) Use n to relate the size dS of the area element at a point on the surface S1 to its projection dxdy in the xy-plane. The Attempt at a Solution To...
  50. C

    How to do cyclic permutation on interatomic matrix elements?

    For example, how to obtain E_(yz,xz)(l,m,n) from E_(xy,xz)(l,m,n)?
Back
Top