Elements Definition and 1000 Threads

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.

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  1. S

    Info on handling dangerous elements

    Hello, I want to do an activity with my students where we study some basic properties of some elements of different groups. I'm concerned about some hazards with some of these elements. I work under a simple fume hood. My concerns are: - Pure Sodium/lithium/magnesium: Is it safe to handle at...
  2. M

    I Matrix elements of Hamiltonian include Dirac delta term

    Currently reading a textbook on non-equilibrium green's functions and I'm stuck in chapter 1 where it recaps just general quantum mechanics because of dirac deltas included in the matrix elements of a generalized hamiltonian. The textbook gives this: I just don't understand how to think about...
  3. dddd

    What Makes Iodine So Fascinating? Exploring the World of Elements

    I’m currently fascinated by the the element iodine. Hoping to find out more about this topic, and other elements.
  4. fluidistic

    LaTeX Most awesome periodic table of the elements in Latex?

    I would like to print a nice PTOTE, written in Latex. So that I could make small modifications before printing it. I have checked on the Internet, but surprisingly couldn't find any really nice one. Ideally, it should contain information like the fusion point, possibly crystallographic...
  5. D

    B What Would Happen to the Elements in the Human Body If Teleported to the Sun?

    The human body is made up of mostly oxygen, hydrogen, nitrogen, carbon, calcium, and phosphorus. Less than 1% is sulfur, potassium, sodium, chlorine, and magnesium. If a human body was teleported to the surface of the sun, what would happen to these elements? Which ones would cease to exist...
  6. manareus

    Engineering Machine Elements: are both of these constructions basically the same?

    The construction just basically a bracket that is being held in place by welds and bolts and there is a force acting on it. The textbook answered the first construction and the free-body diagram is shown like this below: I apologize for the picture not being in English, here's the...
  7. cwill53

    Quantum Workforce Elements, Toolbox for QIS Programs at Universities

    TL;DR Summary: Imagine you have infinite funds and cooperation to build a very ideal curriculum and student organization, both dedicated to quantum information science, at a university. What does this look like pedagogically? How would this be structured? What resources do students need access...
  8. Lotto

    B For what elements does Born–Oppenheimer approximation fail the most?

    I would say that for the elements with the lowest atomic numbers, because these elements have their nuclei the lightest and so they can move more and their movement influence electrons more than in some heavier elements, whose nuclei move less. Am I right or not?
  9. fluidistic

    I Finding the weak form of an eq. with DG elements (finite elements)

    My goal is to numerically solve (finite elements using FEniCSx software) Ohm's law ##\vec J = \sigma \vec E##, where ##\vec E = -\nabla V##, ##\vec J## is given (the current density is given on some boundaries), and ##\sigma## is algo given (the electrical conductivity). The problem is solved...
  10. A

    I Determining elements of Markov matrix from a known stationary vector

    Hi, For a 2 x 2 matrix ##A## representing a Markov transitional probability, we can compute the stationary vector ##x## from the relation $$Ax=x$$ But can we compute ##A## of the 2x2 matrix if we know the stationary vector ##x##? The matrix has 4 unknowns we should have 4 equations; so for a ##A...
  11. A

    Engineering Limiting the torque and safety torque elements

    Greetings I need to identify the elements of the following safety cluches: we have three different clutches. I lready identified most of them exept for number 14 Any help would be appreciated ! thank you! 1- output shaft 2-friction surface 3-preloaded spring 4-nut 5- input shaft 6- output...
  12. M

    A When should you use more mesh elements in the finite element method?

    the simple rectangular isoparametric element (curved edges element) can be used to generate many complex shapes like.. square to circle square to triangle two square elements to annular. and the results i calculated in python code (2D case) are very accurate, then i confused why to use complex...
  13. bob012345

    I FEM Method in 2D with Triangular Elements

    I have worked through the basics of the FEM method in 2D with rectangular elements and now am trying to learn triangular elements but need a simple enough numerical example. It seems triangular elements are far more complicated and also depend on the global coordinates thus each local stiffness...
  14. theycallmevirgo

    Why do throat mics almost always have 2 elements?

    Most things like this https://www.coderedheadsets.com/Assault-MOD-Waterproof-Tactical-Throat-Mic-p/assault-mod-wp.htm generally have 2 transducers. Why? If for phased array noise cancellation, can someone give a broad outline of the "summing" circuit?
  15. A

    I Changing diagonal elements of a matrix

    I have a variance-covariance matrix W with diagonal elements diag(W). I have a vector of weights v. I want to scale W with these weights but only to change the variances and not the covariances. One way would be to make v into a diagonal matrix and (say V) and obtain VW or WV, which changes both...
  16. M

    Hypothetical stable isotope of Promethium?

    Say one was to create an artificial stable isotope of Promethium as it has predicted applicable properties. What would it’s number have to be? I know Promethium-147 is semi-stable.
  17. A

    I Understanding the diagonal elements of the transition dipole moment

    Hey guys, I just numerically calculated the matrix elements for a superconducting qubit and I'm having some trouble to interpret the result. I will include a plot of the matrix I got below: I basically have "large" non zero elements on the main diagonal of this matrix. In previous courses I...
  18. WMDhamnekar

    Elements of Combinatorial Analysis

    ##P_m(r + 1, n)= n^{-r}\cdot E_m(r + 1, n), E_m(r + 1, n)= \binom{n}{m} A(r+1, n-m) = \binom{n}{m} \displaystyle\sum_{v=0}^{n-m}(-1)^v \binom{n-m}{v}(n-m-v)^r ## ##P_{m+1}(r, n) = \binom{n}{m} A(r, n-m-1) =\binom{n}{m+1} \displaystyle\sum_{v=0}^{n-m-1}(-1)^v \binom{n-m-1}{v}(n-m-1-v)^r...
  19. F

    Why serendipity elements are called serendipity?

    title
  20. A

    I Radioactive Dating of Asteroid Elements: How Do Scientists Know?

    When scientists use radioactive dating of elements in the asteroids to determine the age of the solar system, how do they know what the original amount of the radioactive element that was in the rock was? Do they need to know what the original amount of the radioactive element was in the rock...
  21. M

    MHB How do we distribute the elements into schedules?

    Hey! :giggle: The transactions $T_1, T_2,\ldots , T_7$, the database elements $A, B, C, D, E$ and the below multiset are given Now distribute the twenty elements from $M$ in three different ways so that three different schedules $S_1$, $S_2$ and $S_3$ arise. Also make sure that $S_1$ is a...
  22. Y

    MHB Group Elements of Z24: Find the Order

    Determine the order of every element of Z24
  23. D

    I Irreducible polynomials and prime elements

    let p∈Z a prime how can I show that p is a prime element of Z[√3] if and only if the polynomial x^2−3 is irreducible in Fp[x]? ideas or everything is well accepted :)
  24. N

    B Are quarks fundamental elements of matter?

    I would like to ask scientists or anybody: what do you think about qwarks, do you consider them to be the littiest parts of matter or that matter is cyclically or infinitaly smalling, like numbers, or that there are some smaller parts, which have not been observed, but they have an end in their...
  25. J

    A Probability distributions in an ordered set of extracted elements

    Hello, I tried looking for an existing solution for the following problem: "Assume that S is a set of d elements, and R is a total order relation on S. Assume that n elements are randomly extracted from S, and then they are ordered according to R. Which is the probability that in the i-th...
  26. F

    Weak solutions under finite elements

    Finite elements give weak solutions, that is, the solutions to a PDE are only correct in its integral form. Is it possible that in finite element software, the solution differs a lot from the analytic one locally while it's exact in its integral form (globally)?
  27. Mayhem

    Chemical inhibitions of radioactive elements

    Is it possible to chemically inhibit (block/absorb) ionizing radiation from radioactive elements, and is any research being done in this area to use it for long term storage of nuclear waste (in conjunction with other precautions, of course)?
  28. Positronix

    What is the percentage of elements in a compound?

    Thanks in advance for explaining this to me. I have a very small sample of thorium dioxide in a sealed ampoule (reasonably pure) as an example of thorium for a display. Every time I wonder what % of the compound is thorium people start talking moles and grams and envisioning it in a...
  29. A

    I Purpose of Tensors, Indices in Tensor Calculus Explained

    I would like to know what is the utility or purpose for which the elements below were defined in the Tensor Calculus. They are things that I think I understand how they work, but whose purpose I do not see clearly, so I would appreciate if someone could give me some clue about it. Tensors. As...
  30. M

    Elements of the set {6a + 2b} where a and b....

    I've boxed around my answer but I don't know if this is the right answer. I also used a substitution with c=3a+b in my work. I don't know if my work is precise or not.
  31. M

    Finding the elements of these sets

    Can anyone please check/confirm my answers? I've shown my work and I boxed around all of my answers. Thank you.
  32. M

    Elements in Sets: Check/Confirm Answers

    Can anyone please check/confirm my answers if they are correct or not? I boxed around my answers just to be clear and understanding. Thank you.
  33. M

    B Questions about dark matter, matter and elements

    Hello. I'm posting here for the first time. I have a few related questions about matter, dark matter and elements for which I have not been able to find answers. Does dark matter 'hold' matter in the universe in place? Does matter 'hold' the elements of the universe in place? Does matter create...
  34. Hamiltonian

    Moment of inertia of a disc using rods as differential elements

    I know there are more convenient differential elements that can be chosen to compute the moment of inertia of a disc(like rings). the mass of the differential element: $$dm = (M/\pi R^2) (dA) = (M/ \pi R^2) (2\sqrt{R^2 - y^2})(dy)$$ the moment of inertia of a rod through its COM is...
  35. DaveC426913

    Troubleshooting stove heating elements

    Plz forgive. Old man fingers on young whippersnapper phone kb. This stove takes an hour to boil a pot of water. I'm looking at replacing the burners right now. They look brand new (top) but who knows? I bought this one (bottom) which is not exactly the same one. The prongs will fit but the new...
  36. W

    A How do heavier nuclei maintain stability despite requiring energy for fusion?

    I understand overall decrease in potential energy of Lighter nuclei releases energy on Fusion- but for heavier nuclei - energy is required- means overall potential energy is not decreased - than how these heavier nuclei sustained their stability.
  37. Mr Davis 97

    Dimension of set of all linear maps that map three elements to zero

  38. H

    Quantum Elements of Modern Physics book recommendations?

    Hello, undergrad Physics student here. I have a course called "Elements of Modern Physics" this semester. Looking for some good book recommendations. Note that I need a book for self-study as I have decided to skip out on lectures because they are online right now and combined with a bad prof...
  39. S

    Can we write mass in coefficients of elements in a chemical equation

    let's take a chemical equation - CH4+2O2 ------> CO2+2H2O From Reactant side- the coefficient of CH4 is 1 and the coefficient of O2 is 2 From Product side - the coefficient of CO2 is 1 and the coefficient of H2O is 2 we can write this chemical equation in terms of molecules,atoms,moles. Can we...
  40. murshid_islam

    B Finding the Point: Unveiling Euclid's 'Elements' Redux

    The following proof (in the image below) is from the book Euclid's "Elements" Redux (by Daniel Callahan and John Casey). I did not understand why the point D or the ##\triangle \rm ABD## was necessary. (I mean, what was the "point" of D? :-p) Joking apart, wasn't this sufficient: suppose we have...
  41. BWV

    B Creation and distribution of elements - looking for recommendations

    Looking for good sources, something beyond typical popular science but readable for a layperson that details current thinking on how various elements get created and distributed over time (supernova, neutron star mergers etc) and implications for evolution of life. Any recommendations?
  42. J

    Prove that Casimir operators commute with the elements of Lie algebra

    I want to show that ##[C, a_{r}] = 0##. This means that: $$ Ca_{r} - a_{r}C = \sum_{i,j} g_{ij}a_{i}a_{j}a_{r} - a_{r}\sum_{i,j} g_{ij}a_{i}a_{j} = 0$$ I don't understand what manipulating I can do here. I have tried to rewrite ##g_{ij}## in terms of the structure...
  43. A

    I Add an exponential number of elements, what will be the final cardinality?

    Suppose we construct a set, adding at each step a polynomial number of elements. My impression that after we do countably infinite number of steps, the set will have countably infinite cardinality. But what happens if we add exponential number of elements each step? For instance, on step 0 we...
  44. S

    Python 4D array with elements only on one side of the diagonal

    Given the parameters ##n## and ##m##, I'd like to initialize a ##n \times n ## 4D array where each entry is an ##m \times m ## matrix, and where each column of the matrix is an array of type numpy.linspace(0,1,m). Furthermore, I'd only like to have entries on the diagonal and above it, or only...
  45. S

    Converting State Vectors to Keplerian Orbital Elements for Binary Objects

    Homework Statement:: I'm working on a personal project to convert objects from a simulation using state vectors for position and velocity to Keplerian orbital elements (semimajor axis, eccentricity, argument of periapsis, etc.). However, the equations I am using do not calculate the...
  46. L

    MHB How Many Elements Are Found in Each Mathematical Set?

    Question: How many elements are in each set? For the first set, I think it's 8995 because the set is the union of {1,2,3,4,5},{1,2,3,4,5,6},...{1,2,3,...9000}. So 9000 - 5 = 8995. For the second set, I'm not too sure about counting the elements in the set. Since 1<x≤i, I can't think of any x...
  47. A

    MHB What Are the Elements of (Z4×Z12)/<2,1>?

    List all elements of \[ (Z_4\times Z_{12})/<2,1> \]
  48. M

    MHB Show that these elements are linearly independent

    Hey! 😊 Let $1\leq n\in \mathbb{N}$, let $\mathbb{K}$ be a field, $V$ a $\mathbb{K}$-vector space with $\dim_{\mathbb{K}}V=n$ and let $\phi:V\rightarrow V$ be linear. - Let $0\neq v\in V$ and $1\leq m\in \mathbb{N}$, such that $\phi^{m-1}(v)\neq 0=\phi^m(v)$. Show that $\phi^0(v)=v, \phi (v)...
  49. F

    I How to define infinite extent elements in COMSOL?

    This figure shows 2 capacitor plates. Except the region in between the 2 plates, I want to set the others as infinite elements. How to 'stretch' the x and y directions in the infinite element settings?
  50. C

    A Off-diagonal elements in a density matrix

    Hello everyone, I have a math / physics question that has been with me for a while. I would be grateful if someone could help me. Given a density matrix, what is the minimum value a sum of some of its off-diagonal elements can assume (or the most negative value)? Remark: if one collect an...
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