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. V

    Operator matrix elements, opposite-parity functions

    Homework Statement For operator H=f(r)γ , where γ=\bigl(\begin{smallmatrix} 0 & I\\ I& 0 \end{smallmatrix}\bigr) , f(r) some even function. Show that matrix element of this operator <\psi_{a}|H|\psi_{b}> is non-vanishing only if ψ_a and ψ_b functions are of the opposite parity...
  2. G

    What causes some elements to be conductive and other element to resist?

    Hi Guys, I am new here I have been programming for some time in C/C++/etc,but my knowledge in physics/chemistry I am currently improving I wanted to know why is the causes that makes some elements resist and some other elements conduct electricity ?
  3. K

    Ms temperature raiser elements other than Cobalt?

    Hi, Is there any elements or compounds other than cobalt, which raise martensite start temperature during solidification of steel.
  4. R

    Process to form elements in quantity

    Do macro amounts of elements form when atoms of a certain type (e..g. gold) bond together to form a substantial mass? Or do atoms of mixed types bond together and then together take on the properties we ascribe to each element? The reason I ask is that it seems improbable to me that a few...
  5. R

    Elements that can be oxidizing AND reducing agents?

    Hello people, so there is a gr.11 chem question that I've been struggling with... a) Identify three oxidizing agents (other than Fe2+) from the redox table that can also react as reducing agents. b)try to explain this suprising behavior. so, any ideas? i have a redox table in my textbook...
  6. L

    How Do Maxwell Elements in Parallel Derive Force Elongation Relationships?

    Homework Statement Not sure this is the right place for this but here it goes... I am trying to figure out the derivation of the force elongation relationship of the maxwell elements in parallel in order to derive it for the Kelvin Voigt elements in series. I have attached the material that I...
  7. R

    Heavy Elements Accumulate in Earth: Why?

    In layman's language, why have the heavy elements, which were created atom by atom over enormous periods of time, accumulated into large masses into small spaces as we find in the earth, rather than being scattered uniformly? E.g nuggets, and veins of silver and gold.
  8. T

    Simple Algebra Proof: Finding all elements of a Group, S.

    Homework Statement Find all elements x in S4 such that x4 = e. (e is the identity) Homework Equations Cycle notation is advised. The Attempt at a Solution I know there are 4 elements in this (1 2 3 4). And I feel like I need to find the order of S which can be found by finding the number...
  9. L

    How to predict which elements will have a certain oxidation state?

    Homework Statement I have a test coming up and some of the practice questions were things like "Name 6 elements with a maximum oxidation state of +7" or some other number like +8, +6, etc. How do I go about doing this? The Attempt at a Solution There is the obvious trick of counting...
  10. M

    Order of elements in finite group

    Homework Statement If G is a finite group such that all elements have prime order(other than the identity). If G has a non-trivial center then show every element has the same order. Homework Equations The Attempt at a Solution Since we know that G has a center, we know that...
  11. E

    Infinite groups with elements of finite order

    Can anyone think of an example of an infinite group that has elements with a finite order?
  12. S

    Decide if specified elements are linearly independent, span V, and form a basis

    Homework Statement "In each of the given cases, decide whether the specified elements of the given vector space V (i) are linearly independent, (ii) span V, and (iii) form a basis. Show all reasoning. V is the space of all infinite sequences (a0, a1, a2, ...) of real numbers v1 =...
  13. S

    Matrix elements of the time development operator (position representation)

    Homework Statement There is a freely moving particle of mass m. Prove that the matrix elements of the time development operator, T(t,0), in the position representation is <q'|T|q''> = [(m/2i*pi hbar t)^1/2] Exp[-m(q'-q'')^2/2it hbar] Homework Equations H = (p^2)/2m The Attempt at a...
  14. F

    Proving that a subspace must have a specific number of elements

    Homework Statement Let V = (F2)^3, the set of triples (x; y ; z) of numbers in F2, the fi eld with two elements. V is a vector space over F2. Prove that any subspace of V must have either 1, 2, 4, or 8 elements. Homework Equations F2 = {0,1} The Attempt at a Solution The only...
  15. Pengwuino

    Voltages in bathroom appliance heating elements

    I'm doing a lecture on electricity for my class and one of the students at the beginning of the semester wanted to know how a curling iron works. So I've never ripped open a curling iron but I assume there's coils of wires within the little 'arm' parts that rely on ohmic heating. However, since...
  16. J

    Forming set with infinite elements

    using only the empty set, pairs, and unions can you form sets with infinitely many elements?
  17. S

    Struct array memory layout of the elements

    hi every one , i am new in data structure course i need help in this : Struct Person { Char name[20]; int id; float gpa; }; Person student[5]; Compute the addresses of all the elements of array student and show a memory layout for the array if the address of the first...
  18. C

    Understanding proof about A(adj A) elements

    Hey everyone, I've been going thru a linear alg textbook and there's this one theorem I can't quite follow. It proves that the elements of A(adj A) are |A| if on the diagonal and are 0 if not. Therefore, A(adj A) = |A|I. The first part shows that along the diagonal of this product A(adj...
  19. T

    What are the criteria for classifying elements as metalloids and halogens?

    I'm currently studying grade 11 chemistry... And the periodic table of elements slightly confuses me. I am having trouble understanding which are metalloids, and halogens. In the handout that my teacher gave me, it listed the following as metalloids: B, Si, Ge, As, Sb, Te, Po, and At. It also...
  20. A

    Intersection of sets with infinite number of elements

    I have to decide whether the following is true or false: If A1\supseteqA2\supseteqA3\supseteq...are all sets containing an infinite number of elements, then the intersection of those sets is infinite as well. I think I found a counterexample but I'm not sure the correct notation. I to...
  21. S

    Proving the Differential of $\det (A)$ with Differentiable Elements of t

    Homework Statement PROVE: If A(t) is nxn with elements which are differentiable functions of t Then: \frac{d}{dt}(det(A))=\sumdet(Ai(t)) where Ai(t) is found by differentiating the ith row only. Homework Equations I know I should prove this by induction on n The Attempt at a...
  22. T

    Super Novas Create Heavy Elements: Does this absorb or release energy?

    A massive star collapses when it begins to create iron in the normal fusion sequence. Iron absorbs energy. The collapse then produces all the heavier elements. When the heavier elements are created is energy absorbed or released?
  23. S

    Why in periodic table normally we have elements with FCC and HCP structure?

    what is basic principle followed by atoms to arrange in basic structure?
  24. S

    Equating Field of Elements via the Radix

    Is there a way of calculating the field of elements in a system using the base? I expect that's the main way, I am just unlearned. For Example base phi: (1+√5)/2 has the FoE Q[√5] = Q + [√5]Q Is it just any non-rational elements are added to the field? what would base: (√2 / √7) be?
  25. J

    Replacing specific array elements in IDL

    Replacing specific array elements in IDL - solved! Hi I was just wondering if there was any way, other than using FOR loops, to replace specified elements of an array? For example, say A is a 1D array of 50 elements, each equal to 1.0. Is it possible to change say elements 0-9 and 30-49...
  26. Y

    Line integrals distance elements

    in line integrals we always need a vector element of distance. I can't understand the difference between ds and dr. is ds for all kinds of paths (even curly ones) and dr only for straight lines, or theyre the same? I am confused, or maybe dr is just the magnitude of ds, and the vector here is...
  27. H

    What is the essential elements of being a mathematician

    I just want to know, what are the essential elements of being a mathematician? Because I want to decide whether I am better to study physics or mathematics in the University. I knew that a lots of people learn mathematic olympiads and got a good result in the competition...
  28. A

    MATLAB Defining a Struct with Multiple Elements

    Hi The following structure has 2 elements. people = struct(... 'name',{'bob', 'john'},... 'numKids',{0, 2}, ... 'kidsage',{[],[12,9]}); each element people(1), people(2) has three frields (name, numKids, kidsage) Instead of declaring the structure in one line as above...
  29. B

    MATLAB Grab elements from a vector thru formula, matlab

    I have a vector, say v = [ 1 2 3 4 5 6 ...] ' and suppose that I want to first take the first n elements and place them somewhere else, then the next n-1 elements and place them somewhere else, and so on... How would I do the indexing if it were performed in a loop? So for example, if v = [ 1...
  30. Shackleford

    Finding Distinct Elements of G/H in Symmetric Group S4

    http://i111.photobucket.com/albums/n149/camarolt4z28/IMG_20110804_134032.jpg?t=1312484230 http://i111.photobucket.com/albums/n149/camarolt4z28/IMG_20110804_134038.jpg?t=1312484242 I found that the order of G/H is 6. According to the Lagrange's Thereom, order of G = order of H *...
  31. U

    Why do some elements have more than one charge in specific reactions?

    Why do certain elements (particularly transition metals) possesses varying charges in different reactions? For example: Iron (Fe), is known to exist as Iron2+ and 3+.
  32. S

    Mathematica [Mathematica] Finding equal elements in a list

    I have a nested list of the type: {{1, 2, 3}, {1, 2, 4}, {1, 1, 2}} I want to find the number of sublists in which the first two elements are equal, so in this case that's one (the sublist {1, 1, 2}). Is this possible in Mathematica?
  33. A

    Determining the Number of Invertible Elements in Zn

    Can we describe describe n such that Z_n has exactly 12 invertible elements? Thank you
  34. C

    Elements in a Vacuum: What is the Nothingness?

    Is it possible that even in a vacuum that the void space in the vacuum could consist of some other material? What is the median on which gases move, what is the nothingness in between atoms?
  35. D

    Fast random access of elements in a large file

    Hello all, I have a question concerning the best way to access random elements in a large file. I have a single data file of numbers, 12G in size with dimensions 1024x768x16384. My goal is to, as quickly as possible, load, say 16384 of those numbers into memory. Assume these numbers are not...
  36. S

    Can electronegativity be the same for 2 elements?

    Between Sulfur and Iodine, which has more Electronegativity? I read that they both have the same, if so how can i determine in SI2 compound around which atom do the shared electrons spend more with with(Since that is determined by which atom has greater electronegativity) Or maybe they spend...
  37. F

    Find Orbital Elements given Orbital State Vectors

    Hi everyone, I've been banging my head against this problem for a few days now so I'm ready to find some help with it. In short, I have a set of orbital state vectors(a position vector and velocity vector) describing an object's starting position, as well as the mass of the focus, and I...
  38. S

    How many elements of order 2 are contained in S_4?

    Homework Statement How many elements of order 2 does the symmetric group S_4 contain? Homework Equations The Attempt at a Solution I know that transpositions have order two. Moreover, any k-cycle has order k. Thus there are six elements with order two contained in S_4? Is this...
  39. O

    Group/Representation Theory Help (Summations and elements of a finite group)

    Apologies, the LaTeX thing doesn't seem to be working, so not very clear! I am working through a book on representation theory, but am stuck on these exercises. Homework Statement Let G be a finite group and let E = Sum g (running over all g in G). (i) Prove: Ex = E (forall x in G)...
  40. B

    Transients(RC) elements in the circuit after commutation?

    Homework Statement Find I1,I2,I3,Uc Homework Equations I was trying to make this task but my result was not correct Before commutation I=E/(R1+R2)=0.1 A U=0.1*R2=100 V After commutation I=0 A In the moment equatations I1*R1+I1*R2-I3*R2=E I3*R2-I1*R2=Uc I3=C*dUc/dt But when I had got result...
  41. M

    What is the Most Efficient Way to Heat a Small Object Using a Battery?

    i hope I am asking this at the right place i just have a few questions... why does it take so much power (115v) to heat up a small coil(heating element) roughly the size of a spring in a pen. what could get just as hot, maybe a resistor? i have a 18 volt battery from a drill and i need to get...
  42. C

    Set Elements: 2^\emptyset and {x:x \subseteq {1,2,3,4,5} and |x| \leq 1}

    Homework Statement Write out the following sets by listing their elements between the curly braces. a. 2^\emptyset b. {x:x \subseteq {1,2,3,4,5} and |x| \leq 1 The Attempt at a Solution a. I'm not sure if the only element is one, or if this is an undefined operation. b. I think the...
  43. D

    Which finite elements are best for structural analysis in engineering courses?

    i am a 3rd year engineering student currently a course in computer methods for structural analysis, as a part of the course we are learning about finite elemnts, we have learned about CST LST Q4 and Q8, but i am having difficulty deciding which element to use for different models. does anyone...
  44. K

    Elements of odd-order abelian groups are squares.

    Homework Statement Let G be a finite abelian group, and assume that |G| is odd. Show that every element of G is a square. The Attempt at a Solution So we want to show that \forall g \in G, \exists h \in G, g = h^2 . Let g \in G be arbitary, and consider the subgroup generated by g, denoted...
  45. C

    Radioactive Decay: Are stable elements really stable?

    Ok, so all elements undergo radioactive decay. But why? I have been snooping around and what i find is that radioactive decay occurs because of instability of the atom nucleus in quantity, proton-neutron ratio and energy content; therefore we have alpha, beta and gamma decay consecutively...
  46. M

    Question: Can elements above iron actually be clusters of smaller elements?

    Hello, I would like to ask if elements of higher atomic number than iron might actually be clusters made up of smaller elements? Is there any evidence that rules out this possibility? The reason I am guessing that elements below iron are discrete is because of the theory that iron has its...
  47. H

    MATLAB MATLAB if question for each elements

    Hi, I have a question about comparing each and every element in a matrix.. Heres what i have, S1 = 90 S2 = 1 delta = 0.75 SM = 80 m = 0.1:0.01:100; if (S1-S2*m.^(delta))>=SM S_avg = SM elseif (S1-S2*m.^(delta))<SM & (S1-S2*m.^(delta))>0 S_avg = (S1-S2*m.^(delta)) else S_avg = 0...
  48. reddvoid

    6th group elements as dopants to silicon ?

    what will result when 6th group elements are used as dopants to silicon ?
  49. A

    Symmetry Elements of XeF4: Meaning of 2C2 & σh

    In my lecture notes the symmetry elements for XeF4 are listed as: [PLAIN]http://img690.imageshack.us/img690/7216/syms.png but nowhere does it explain what 2C2 or σh means. What are these symmetry operations?
  50. G

    Why is HCP more common than FCC in elemental compositions?

    This may be obvious but since the packing fraction for both hexagonal close packed and face centered cubic is the same (74% i believe) why is HCP more common in elemental compositions?
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