6,587 research outputs found

    La guerre et les maladies vénériennes

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    Parmi toutes les misĂšres matĂ©rielles que la guerre mondiale a dĂ©chaĂźnĂ©es sur l'humanitĂ©, les ravages causĂ©s par le flĂ©au vĂ©nĂ©rien occupent une place considĂ©rable. En vĂ©ritĂ© nous ne somraes pas encore, aujourd'hui, en Ă©tat d'entrevoir les multiples rapports qui relient les maladies vĂ©nĂ©riennes Ă  la guerre; il nous manque des donnĂ©es statistiques exactes portant sur le nombre total des soldats vĂ©nĂ©riens dans les diffĂ©rentes armĂ©es, et plus incomplĂštes encore sont nos connaissances sur l'extension des maladies vĂ©nĂ©riennes dans la population civile des pays belligĂ©rants. Incomplets aussi sont nos renseignements sur toutes les mesures prises par les diffĂ©rents pays et armees pour l'endiguement des maladies vĂ©nĂ©riennes, et surtout sur leurs rĂ©sultats favorables et dĂ©favorables. MalgrĂ© ces lacunes, les faits acquis par l'expĂ©rience sont si nombreux ct importants qu'ils doivent attirer l'attention de tout homme Ă  qui l'avenir de l'humanitĂ© civilisĂ©e tient Ă  cƓur. La guerre mondiale nous a montrĂ© que la lutte contre les maladies vĂ©nĂ©riennes est un problĂšme qui nĂ©cessite d'urgence une prompte solution. Elle a aussi modifiĂ© dans leur essence nos opinions sur les moyens les mieux appropriĂ©s Ă  cette solution. Il y a lĂ , Ă  cĂŽtĂ© de tous les maux et de toutes les tristesses que la guerre a semĂ©s, un bon grain Ă  la germination duquel chaque peuple et chaque race sont intĂ©ressĂ©

    On the significance of quantum effects and interactions for the apparent universality of Bloch laws for M_s(T)

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    The apparent universality of Bloch's T^{3/2}-law for the temperature dependence of the spontaneous magnetization, and of generalizations thereof, is considered. It is argued that in the derivation one should not only consider the exchange interaction between the spins, but also the other interactions between them, leading to elliptical spin precession and deviations from the parabolic dispersion of magnons. Also interaction effects are important to explain the apparent universality of generalized Bloch law exponents e_B, defined by M_s(T)= M_s(0)-const. x T^{e_B}, valid in a wide temperature range T_1 < T < T_2, and for dimensionalities d = 1, 2, and 3. The above-mentioned temperature range, the 'Bloch range', lies above the quantum range, where magnetic long-range order (e.g. in d=2 dimensions) is nontrivially enforced by the additional interactions, but below the thermal critical region, where universal 'anomalous scaling dimensions' apply. In contrast, for the Bloch temperature region, the universality is only apparent, i.e. a crossover-phenomenon, and simple scaling considerations with 'normal dimensions' apply. However, due to interactions, the Bloch exponent e_B depends not only on the dimensionality d of the system, but also on the spin quantum number s (mod (1/2)) of the system, i.e. for given d the Bloch exponent e_B is different for half-integer s and for integer s.Comment: LATEX, 27 pages (including 5 eps-figures); accepted by JMM

    Geometrically constrained magnetic wall

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    The structure and properties of a geometrically constrained magnetic wall in a constriction separating two wider regions are investigated theoretically. They are shown to differconsiderably from those of an unconstrained wall, so that the geometrically constrained magnetic wall truly constitutes a new kind of magnetic wall, besides the well known Bloch and Neel walls. In particular, the width of a constrained wall cann become very small if the characteristic length of the constriction is small, as is actually the case in an atomic point contact. This provides a simple, natural explanation for the large magnetoresistance observed in ferromagnetic atomic point contacts.Comment: RevTeX, 4 pages, 4 eps figures; v2: revised version; v3: ref. adde

    Relatos do processo do meia metragem “O Ouro, O Ladrão e Sua Família”

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    Trabalho de conclusĂŁo de curso (graduação)—Universidade de BrasĂ­lia, Instituto de Artes, Departamento de Artes CĂȘnicas, 2017.Esta monografia tem como objetivo relatar os principais eventos da trajetĂłria de um ano e meio do meia metragem “O Ouro, O LadrĂŁo e Sua FamĂ­lia” dirigido por Leo Sykes, desde os primeiros desejos do que poderia ser, atĂ© as apresentaçÔes finais

    CPV tests with rare kaon decays

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    The K_S \to pi+/- e+ e- decay mode has been investigated using the data collected in 2002 by the NA48/1 collaboration. With about 23k signal events and 59k K_L \to pi+ pi- pi0_D normalization decays, the K_S \to pi+ pi- e+ e- branching ratio was determined. This result is also used to set an upper limit on the presence of E1 direct emission in the decay amplitude. The CP-violating asymmetry has been also measured. We report on measurements of the rare decays K +/- \to pi+/- e+ e- and K+/- \to pi+/- mu+ mu- . The full NA48/2 data set was analyzed, leading to more than 7200 reconstructed events in the electronic and more than 3000 events in the muonic channel, the latter exceeding the total existing statistics by a factor of four. For both channels the selected events are almost background-free. From these events, we have determined the branching fraction and form factors of K+/- \to pi+/- e+ e- using different theoretical models. Our results improve the existing world averages significantly. In addition, we measured the CP violating asymmetry between K+ and K- in this channel to be less than a few percent.Comment: 4 pages, 1 figure, To appear in the proceedings of IX International Conference on Hyperons, Charm and Beauty Hadrons (BEACH2010), Perugia, Italy, 21-26 June 201

    Vortex stability and permanent flow in nonequilibrium polariton condensates

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    The following article appeared in Journal of Applied Physics 109.10 (2011): 102406 and may be found at http://scitation.aip.org/content/aip/journal/jap/109/10/10.1063/1.3576151We study the effects of imprinting a single-quantized vortex on the steady state of a microcavity exciton-polariton condensate generated via parametric scattering. Interestingly we observe two distinct regimes: In the first case, at low polariton densities, the effect of the pulsed probe, containing the vortex state, is to generate a gain response in the condensate lasting for tens of picoseconds during which no dissipation of the circulating currents is detected. In the second regime, at higher densities, the gain lasts much less and the circulation is imprinted directly into the steady state, which acquires permanent rotation for as long as the vortex remains within the condensate. We use two different ways of measuring the circulation of the condensate and demonstrate that in both cases, polariton condensation in the parametric scattering regime can sustain permanent supercurrentsThis work was partially supported by the Spanish MEC (MAT2008-01555 and QOIT-CSD2006-00019), the CAM (S2009/ESP-1503) and FP7 ITNs “Clermont4” (235114). D.S. acknowledges financial support from the Ramón y Cajal program. G.T. is grateful for the FPI scholarship from the Ministerio de Ciencia e Innovació

    Classes de cycles motiviques \'etales

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    Let X be a smooth variety over a field k, and l be a prime number invertible in k. We study the (\'etale) unramified H^3 of X with coefficients Q_l/Z_l(2) in the style of Colliot-Th\'el\`ene and Voisin. If k is separably closed, finite or p-adic, this describes it as an extension of a finite group F by a divisible group D, where F is the torsion subgroup of the cokernel of the l-adic cycle map. If k is finite and X is projective and of abelian type, verifying the Tate conjecture, D=0. If k is separably closed, we relate D to an l-adic Griffiths group. If k is the separable closure of a finite field and X comes from a variety over a finite field as described above, then D = 0 as soon as H^3(X,Q_l) is entirely of coniveau > 0, but an example of Schoen shows that this condition is not necessary.Comment: FInal version, to appear in Algebra and Number Theor

    The Code of Protest. Images of Peace in the West German Peace Movements, 1945-1990

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    The article examines posters produced by the peace movements in the Federal Republic of Germany during the ColdWar, with an analytical focus on the transformation of the iconography of peace in modernity. Was it possible to develop an independent, positive depiction of peace in the context of protests for peace and disarmament? Despite its name, the pictorial selfrepresentation of the campaign ‘Fight against Nuclear Death’ in the late 1950s did not draw on the theme of pending nuclear mass death. The large-scale protest movement in the 1980s against NATO’s 1979 ‘double-track’ decision contrasted female peacefulness with masculine aggression in an emotionally charged pictorial symbolism. At the same time this symbolism marked a break with the pacifist iconographic tradition that had focused on the victims of war. Instead, the movement presented itself with images of demonstrating crowds, as an anticipation of its peaceful ends. Drawing on the concept of asymmetrical communicative ‘codes’ that has been developed in sociological systems theory, the article argues that the iconography of peace in peace movement posters could not develop a genuinely positive vision of peace, since the code of protest can articulate the designation value ‘peace’ only in conjunction with the rejection value ‘war’

    Single-atom imaging of fermions in a quantum-gas microscope

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    Single-atom-resolved detection in optical lattices using quantum-gas microscopes has enabled a new generation of experiments in the field of quantum simulation. Fluorescence imaging of individual atoms has so far been achieved for bosonic species with optical molasses cooling, whereas detection of fermionic alkaline atoms in optical lattices by this method has proven more challenging. Here we demonstrate single-site- and single-atom-resolved fluorescence imaging of fermionic potassium-40 atoms in a quantum-gas microscope setup using electromagnetically-induced-transparency cooling. We detected on average 1000 fluorescence photons from a single atom within 1.5s, while keeping it close to the vibrational ground state of the optical lattice. Our results will enable the study of strongly correlated fermionic quantum systems in optical lattices with resolution at the single-atom level, and give access to observables such as the local entropy distribution and individual defects in fermionic Mott insulators or anti-ferromagnetically ordered phases.Comment: 7 pages, 5 figures; Nature Physics, published online 13 July 201
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