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. 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...
  2. 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)?
  3. S

    MHB Conditions on Matrix Imply Conditions on Elements

    Question 1 The reduced row echelon form of             3 4 17 22 1 2 5 row a b A is equal to             0 0 0 0 0 0 1 2 1 2 0 3 R . (a) What can you say about row 3 of A? Give an example of a possible third row for A. (b) Determine the values of a and b. (c) Determine...
  4. S

    Why do some radioactive elements emit a green glow?

    Hello I am doing radioactivity with my year 10 class and it has set me think about something. I would be grateful for clarification on the following issue and also any other facts that you would like to share that would be of interest to 14 year olds! My issue: all the famous...
  5. Math Amateur

    MHB Prime elements in integral domains

    In Dummit and Foote, Section 8.3 on Unique Factorization Domains, Proposition 10 reads as follows: Proposition 10: In an integral domain a prime element is always irreducible. The proof reads as follows: =========================================================== Suppose (p) is a non-zero...
  6. T

    Current and Voltage of Elements of a Circuit with a Solenoid.

    Ended up figuring out how to solve this problem. I just was not expecting certain parts of the results which lead me to believe I did it wrong.Homework Statement Voltage of battery is 5V Resistors are 5 Ohms The solenoid has no internal resistance 1.Need to find V_2 before switch is opened...
  7. A

    Transitivity for set of 2 elements

    If we have a set of two elements, say S={0. 1} and we defined 0 to be less than 1, would this obey the transitivity axiom? (If a<b and b<c then a<c? ) To me, it seems looks like you need at least 3 elements but I'm not entirely sure.
  8. I

    MHB Does the permutation group S_8 contain elements of order 14?

    Does the permutation group $S_8$ contain elements of order $14$?My answer: If $\sigma =\alpha \beta$ where $\alpha$ and $\beta$ are disjoint cycles, then $|\sigma|=lcm(|\alpha|, |\beta|)$ . Therefore the only possible disjoint cycle decompositions for a permutation $\sigma \in S_8$ with...
  9. shounakbhatta

    What Are the Processes for Manufacturing Elements Heavier Than Iron in Stars?

    Hello, Is there any specific reason that a star is primarily composed of hydrogen and helium and not any other metals? Thanks.
  10. S

    Group of invertible elements of subring of C.

    Homework Statement Let R be a subring of ℂ such that the group of invertible elements U(R) is finite, show that this group is a cyclic group. (Group operation being multiply). Homework Equations The Attempt at a Solution I have the answer, and I got very close to getting there myself before...
  11. P

    How toasters works with the functions of elements in open loop system?

    1. Explain briefly an example of open loop system. At the same time, explain how this example works with the functions of the elements in the system. example is pop up toaster The Attempt at a Solution The pop up toaster can be set for the desireddarkness of the toastedbread. The setting of the...
  12. R

    Proving Finite Order Elements Form a Subgroup of an Abelian Group

    Homework Statement Prove the collection of all finite order elements in an abelian group, G, is a subgroup of G. The Attempt at a Solution Let H={x\inG : x is finite} with a,b \inH. Then a^{n}=e and b^{m}=e for some n,m. And b^{-1}\inH. (Can I just say this?) Hence...
  13. C

    [Chemistry]Composition of elements in empirical formula

    Homework Statement 0.2243 g of compound C give 0.3771 g of carbon dioxide, 0.0643 g of water and 0.2685 g of silver bromide. Determine the empirical formula of the compound. Homework Equations Why the empirical formula only takes C,H and Br into consideration, but singles out Ag? Ans...
  14. T

    Exploring Unknown Elements: Fact or Fiction?

    I've heard chatter about possible new elements on other planets and even hidden on our own, Could this be possible?
  15. M

    What determines the abundance of elements?

    I was just watching a very particular old documentary, when the question hit me. I could probably manage an educated guess, but I don't really know what exactly determines how much of a certain element there is(except H and He, those are obvious).
  16. D

    Engineering Solving for elements on a circuit using KCL and KVL

    Homework Statement calculate the voltages and currents for each element in the circuit? the resistances are as follows R1 = 1 KΩ R2 = 2.4 KΩ R3 = 1.2 KΩ R4 = 1 KΩ R5 = 1.2 KΩ. Vs= 6V Homework Equations Is - I1 = 0 I1 - I2 - I3 = 0 I3 - I4 = 0 I2 + I4 - I5 = 0 -Vs +V1 +V2 +V5 = 0...
  17. micromass

    Calculus Calculus: The Elements by Comenetz

    Author: Michael Comenetz Title: Calculus: The Elements Amazon Link: https://www.amazon.com/dp/9810249047/?tag=pfamazon01-20 Prerequisities: High-School mathematics Level: Undergrad
  18. micromass

    Geometry Euclid's Elements: Free Resources & Amazon Link

    Author: Euclid Title: Elements Free Resources: http://aleph0.clarku.edu/~djoyce/java/elements/elements.html http://farside.ph.utexas.edu/euclid/Elements.pdf Amazon Link: https://www.amazon.com/dp/1888009195/?tag=pfamazon01-20 (please feel free to give more links to good versions)...
  19. micromass

    The Elements of Coordinate Geometry by Loney

    Author: H.M. Schey Title: Div, Grad, Curl, and All That: An Informal Text on Vector Calculus Amazon Link: https://www.amazon.com/dp/0393925161/?tag=pfamazon01-20 Prerequisities: Calculus 1,2,3 Table of Contents: Preface Introduction, Vector Functions, and Electrostatics Introduction...
  20. A

    C/C++ C++ Problem with accessing elements of a character

    Hey guys, I'm having trouble with sampling data from a force/torque sensor. I'm using Serial Com to receive the readings from the sensor, which is stored in a character of with 45 individual elements. What I'm trying to do is to pick out pieces of these data and store them separately. I'm...
  21. A

    Finding Matrix Elements of Operators in Quantum Mechanics

    If you have an operator a represented in some basis l1>, l2> you find its matrix elements by doing Aij = <ilAlj> But more oftenly you are interested in the expectation value of A. So you take: <ψlAlψ>. My teacher tends to call these numbers matrix elements too. But which matrix element...
  22. nomadreid

    Second-order variables: elements of domain only without quantifiers?

    On one side one can define second-order variables as ranging over all elements of Pk(M) for all natural numbers k (P=power set of M, M is the universe of the model, superscript being iteration). On the other side it is sometimes defined as ranging over all first-order relations and predicates...
  23. A

    Graphical to Mathematical representation of changing the order of some elements

    I have a question that is a little hard to explain, since i don't know the name of this method, but I'll try my best, if anyone knows the name please do tell me. So let's say we have three numbers, 1 2 3 (in this order) and we have a container for this numbers: C123 and we have some...
  24. A

    Density matrix off-diagonal elements

    The possible values of the diagonal elements of a density matrix are restricted by the condition \mathrm{Tr}~\rho = 1 . Are there any restrictions on the possible values of off-diagonal elements, apart from the obvious \mathrm{Re}~\rho_{nm} = \mathrm{Re}~\rho_{mn}, \mathrm{Im}~\rho_{nm} = -...
  25. V

    Converting volume elements to area elements

    Homework Statement I need to evaluate an integral of the form: h(\vec{x}) = \int d^3\vec{x}' \frac{\delta(r' - R)}{|\vec{x}-\vec{x}'|} where r' = |\vec{x}'| = \sqrt{x'^2 + y'^2 + z'^2}. Homework Equations The above, and maybe the fact that \delta(g(x)) = \sum_i \frac{\delta(x -...
  26. K

    Posets and minimal elements - Looking for an inductive proof

    Homework Statement Suppose R is a partial order on a set A. Then every finite, nonempty set B \subseteq A has an R-minimal element. Homework Equations Partial orders are characterized by: Reflexivity: xRx Transitivity: xRy \wedge yRz \rightarrow xRz Antisimmetry...
  27. B

    Is there a vector version of The Elements?

    Is there a "vector" version of The Elements? I have noticed that many theorems in classical geometry can be proven using vectors. Thus, I am naturally inclined to believe that pretty much every theorem in the Elements can be proven using vectors (using the vector space axioms and the vector...
  28. caffeinemachine

    MHB O(G)=56. Sylow 2 subgroup has all its elements of order 2.

    Let $G$ be a group of order $56$ having at least $7$ elements of order $7$. 1) Prove that $G$ has only one Sylow $2$-subgroup $P$. 2) All elements of $P$ have order $2$. The first part is easy since it follows that the number of Sylow $7$-subgroups is $8$. I got stuck on part 2. From part 1 we...
  29. caffeinemachine

    MHB Finite group of order 4n+2 then elements of odd order form a subgroup.

    Let $G$ be a finite group of order $4n+2$ for some integer $n$. Let $g_1, g_2 \in G$ be such that $o(g_1)\equiv o(g_2) \equiv 1 \, (\mbox{mod} 2)$. Show that $o(g_1g_2)$ is also odd. I found a solution to this recently but I think that solution uses a very indirect approach. Not saying that that...
  30. B

    Kinematics of Euler Bernoulli and Timoshenko Beam Elements

    Folks, Trying to get some appreciation for what is going on in the attached schematic of 1)Euler bernoulli and 2) Timoshenko beam elements. For the first one, ie the top picture, how was ##u- z \frac{dw}{dx}## arrived at? thanks
  31. J

    How to determine elements based on received frequency from Space?

    I would like to know on how to determine the elements based on received frequency from Space? Such as water H2O Does anyone have any suggestions on where to find the reference materials? Thanks in advance for any suggestions
  32. S

    Abstract Algebra: Rings, Unit Elements, Fields

    1) Show that (R,*,+) is a ring, where (x*y)=x+y+2 and (x+y)=2xy+4x+4y+6. Find the set of unit elements for the second operation. I understand that the Ring Axioms is 1. (R,+) is an albein group. 2. Multiplication is associative and 3. Multiplication distributes. I just don't understand how to...
  33. R

    Transpose a matrix whose elements are themselves matrices

    If I have (for simplicity) a vector ( A, B) where A and B are matrices how does the transpose of this look, is it ( AT, BT) or (AT BT)
  34. Z

    Calculate the elements of the Riemann tensor

    Homework Statement Compute 21 elements of the Riemann curvature tensor in for dimensions. (All other elements should be able to produce through symmetries) Homework Equations R_{abcd}=R_{cdab} R_{abcd}=-R_{abdc} R_{abcd}=-R_{bacd} The Attempt at a Solution I don't see how 21...
  35. S

    Why Do Elements Behave Differently as Gas or Liquid?”

    Hello, why the same quantity of different elements behave in the same way (take about 22,4 L) when they are gas and they don't when they are liquid ?
  36. Feodalherren

    # of atoms when combining elements

    Homework Statement One liter of nitrogen combines with 3 L of hydrogen to form 2 L of ammonia. If the molecules of nitrogen and hydrogen have two atoms each, how many atoms of hydrogen and nitrogen are in one molecule of ammonia? Homework Equations Chemical equations The...
  37. M

    MHB Abelian Groups of Order $2100$: Elements of Order $210$

    Find all the abelian groups of order $2100.$ For each group, give an example of an element of order $210.$ $2100 = 2^2 \cdot 3 \cdot 5^2 \cdot 7,$ then $G_1 = \mathbb{Z}_2 \times \mathbb{Z}_2 \times \mathbb Z_3 \times \mathbb{Z}_5 \times \mathbb{Z}_5 \times \mathbb{Z}_7 \cong \mathbb Z_{10}...
  38. V

    Number of elements for a given probability?

    Homework Statement Let A be a set with 8 elements and B be a set such that A U B has 12 elements. What is the number of elements in P(B\A) U P(∅)? Homework Equations The Attempt at a Solution I have no idea what it means to ask what are the number of elements in a probability.. Is it the...
  39. P

    Atomic radii of transition elements

    Hi, my question is regarding atomic radii of transition elements. When we move to the right of the periodic table (in the region of the transition elements) the atomic number increases, thus there is one more proton in the nucleus and on more electron in the atom. The nuclear charge increases...
  40. R

    If I have two elements A and B, is the compound AB the same as BA?

    Is there a specific reason for how compounds are named? Like NaCl for instance, what's the criteria to have NaCl rather than ClNa?
  41. D

    Where Can I Find Crystal Structures of Pure Elements?

    Hi, suppose I want to look up the crystal structure of a pure element (for example, the structure of pure Tellurium), is there an online database or reference to easily find this information? Thanks.
  42. B

    Plane Trusses Finite Elements 2 - Assembled Matrix

    Folks, I am having difficulty understanding how this global matrix is assembled with the naming convention used as shown in attached. The numbers in the corners such as 1(1,2) etc in figure 4.6.3 (b) denote the global and element numbers respectively. Can anyone shed light on how this...
  43. N

    Formation of elements heavier than iron

    I know that in the process of fusion in Stars, the hydrogen fuses into helium and so on until Iron is formed. The fusion stops after the formation of Iron and the graviatational force wins to take over the star evolution. Then how do we account for the elements which are havier than Iron?
  44. B

    Transformation between Global and Local Coordinates for Uniform Bar Elements

    Folks, The element equations for a uniform bar element with constant EA according to the attachment is given as ##\displaystyle \frac{E_a A_e}{h_e}\begin{bmatrix} 1 &0 &-1 &0 \\0 &0 &0 &0 \\-1 &0 &1 &0 \\ 0 &0 &0 &0 \end{bmatrix}\begin{Bmatrix} u^e_1\\v^e_1 \\u^e_2...
  45. C

    Clarification of statement on how to evaluate S-matrix elements.

    Hi. I'm trying to understand a statement from the book Field Quantization on the evaluation of the S-matrix elements for a certain initial and final state in QED. The author states, if one is evalutating a matrix element on the form \langle k_1' \lambda_1', \ldots, \bar p_1' \bar s_1'...
  46. C

    Does first order QED matrix elements vanish?

    Hi! I'm trying to learn the Feynman rules trough Wick's theorem right now and I'm focusing on QED. Here the first order term of the S-operator can be written as -ie\int d^4x :\bar \psi(x) \gamma^\mu \psi(x) A^\mu(x): but the author of the book I'm reading (Greiner Reinhart) claims that all...
  47. G

    Finding Equivalence Relations in a Set of 4 Elements - Juan's Question

    Our math Teacher asked us to find how many equivalence relations are there in a set of 4 elements, the set given is A={a,b,c,d} I found the solution to this problem there are 15 different ways to find an equivalence relation, but solving the problem, i looked in Internet that the number of...
  48. K

    Problem Involving Counting of Elements in Three Sets

    Problem: -The Union of set A, set B and set C has 104 elements. -The Union of Set A and B has 51 elements -The Union of Set A and C has 84 elements -The Union of Set B and C has 97 elements -The Intersection of Set A and the Union of Set B and C has 17 elements. -Set C has twice as many...
  49. S

    Partially specified elements of a group?

    Is there a technical term in group theory for (what I would call) partially specified elements of a group? I mean "partially specified" in the following sense: An elements of a group acts as permuation on the set of elements of the group. So a group element can be considered to be a function...
  50. S

    How Are Elements Beyond Iron Created in Stars?

    A friend wrote this in an exchange we had about iron and its role in the process of fusion. I question the last sentence. Is it right, and what is the "coating"? The creation of the element iron via fusion "is the final peal of a star's natural life" (if the star is massive enough to even get...
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