987 resultados para 1-D
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We investigate spectral functions extracted using the maximum entropy method from correlators measured in lattice simulations of the (2+1)-dimensional four-fermion model. This model is particularly interesting because it has both a chirally broken phase with a rich spectrum of mesonic bound states and a symmetric phase where there are only resonances. In the broken phase we study the elementary fermion, pion, sigma, and massive pseudoscalar meson; our results confirm the Goldstone nature of the π and permit an estimate of the meson binding energy. We have, however, seen no signal of σ→ππ decay as the chiral limit is approached. In the symmetric phase we observe a resonance of nonzero width in qualitative agreement with analytic expectations; in addition the ultraviolet behavior of the spectral functions is consistent with the large nonperturbative anomalous dimension for fermion composite operators expected in this model.
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We prove that if f is a partially hyperbolic diffeomorphism on the compact manifold M with one dimensional center bundle, then the logarithm of the spectral radius of the map induced by f on the real homology groups of M is smaller or equal to the topological entropy of f. This is a particular case of the Shub's entropy conjecture, which claims that the same conclusion should be true for any C1 map on any compact manifold.
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RATIONALE: AICAR (5-aminoimidazole-4-carboxamide 1β-D-ribofuranoside) is prohibited in sport according to rules established by the World Anti-Doping Agency. Doping control laboratories identify samples where AICAR abuse is suspected by measuring its urinary concentration and comparing the observed level with naturally occurring concentrations. As the inter-individual variance of urinary AICAR concentrations is large, this approach requires a complementary method to unambiguously prove the exogenous origin of AICAR. Therefore, a method for the determination of carbon isotope ratios (CIRs) of urinary AICAR has been developed and validated. METHODS: Concentrated urine samples were fractionated by means of liquid chromatography for analyte cleanup. Derivatization of AICAR yielding the trimethylsilylated analog was necessary to enable CIR determinations by gas chromatography/combustion/isotope ratio mass spectrometry. The method was tested for its repeatability and stability over time and a linear mixing model was applied to test for possible isotopic discrimination. A reference population of n = 63 males and females was investigated to calculate appropriate reference limits to differentiate endogenous from exogenous urinary AICAR. These limits were tested by an AICAR elimination study. RESULTS: The developed method fulfills all the requirements for adequate sports drug testing and was found to be fit for purpose. The investigated reference population showed a larger variability in the CIR of AICAR than of the endogenous steroids. Nevertheless, the calculated thresholds for differences between AICAR and endogenous steroids can be applied straightforwardly to evaluate suspicious doping control samples with the same statistical confidence as established e.g. for testosterone misuse. These thresholds enabled the detection of a single oral AICAR administration for more than 40 h. CONCLUSIONS: Determination of thee CIRs is the method of choice to distinguish between an endogenous and an exogenous source of urinary AICAR. The developed method will enable investigations into doping control samples with elevated urinary concentrations of AICAR and clearly differentiate between naturally produced/elevated and illicitly administered AICAR.
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Sota el títol de Biblioteconomía y Documentación en la era digital: docencia e investigación, l'Observatori de la Comunicació Científica, la Secció Científica de Biblioteconomia i Documentació del Departament de Ciències Polítiques i Socials i l'Institut de Lingüística Aplicada (IULA) de la Universitat Pompeu Fabra organitzaren en les dates ja esmentades el I Encuentro Británico-Español de Profesores de Biblioteconomia y Documentación a la seu de la Rambla d'aquesta Universitat. Han col·laborat en aquesta activitat, a més, el Ministerio de Educación y Cultura, el Departamento de Biblioteconomía y Documentación de la Universidad Carlos III de Madrid, la Llicenciatura en Documentació de la Universitat Autònoma de Barcelona, la Llicenciatura en Documentació de la Universitat de Barcelona, la Llicenciatura en Documentació de laUniversitat Oberta de Catalunya, el Col·legi Oficial de Bibliotecaris-Documentalistes de Catalunya (COBDC) i la School of Information and Media Robert Gordon University. Pel nombre d'institucions implicades i pelseu alt nivell, es constata fàcilment que la trobada naixia amb molt bons auguris.
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Aquesta publicació conté el programa d'activitats previst per l'XIè Congrés d'Història de Medicina Catalana, cel·lebrat a l'edifici de la Reial Acadèmia de Medicina de Catalunya. També conté una petita història i descripció de la seu del congrés.
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Soitinnus: piano.
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Donateur : Bonaparte, Roland (1858-1924)
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[Acte. 1711-10-20. Versailles]
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Collection : Classiques pour tous