4,783 research outputs found

    A Note on the Robustness of Pair Separations Methods in Cosmic Topology

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    The pair separations statistical methods devised to detect the topology of the universe rely on the accurate knowledge of the three-dimensional positions of the cosmic sources. The determination of these positions, however, involves inevitable observational uncertainties. The only significant (measurable) sign of a nontrivial topology in PSH's was shown to be spikes. We briefly report our results concerning the sensitivity of the topological spikes in the presence of the uncertainties in the positions of the cosmic sources, which arise from uncertainties in the values of the density parameters.Comment: To appear in the Proc. of 10th Marcel Grossmann Meeting on General Relativity. Latex2e, World Scientific proc. style files, 2 figs., 4 page

    Solving 1ODEs with functions

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    Here we present a new approach to deal with first order ordinary differential equations (1ODEs), presenting functions. This method is an alternative to the one we have presented in [1]. In [2], we have establish the theoretical background to deal, in the extended Prelle-Singer approach context, with systems of 1ODEs. In this present paper, we will apply these results in order to produce a method that is more efficient in a great number of cases. Directly, the solving of 1ODEs is applicable to any problem presenting parameters to which the rate of change is related to the parameter itself. Apart from that, the solving of 1ODEs can be a part of larger mathematical processes vital to dealing with many problems.Comment: 31 page

    Paramagnetic reentrant effect in high purity mesoscopic AgNb proximity structures

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    We discuss the magnetic response of clean Ag coated Nb proximity cylinders in the temperature range 150 \mu K < T < 9 K. In the mesoscopic temperature regime, the normal metal-superconductor system shows the yet unexplained paramagnetic reentrant effect, discovered some years ago [P. Visani, A. C. Mota, and A. Pollini, Phys. Rev. Lett. 65, 1514 (1990)], superimposing on full Meissner screening. The logarithmic slope of the reentrant paramagnetic susceptibility chi_para(T) \propto \exp(-L/\xi_N) is limited by the condition \xi_N=n L, with \xi_N=\hbar v_F/2 \pi k_B T, the thermal coherence length and n=1,2,4. In wires with perimeters L=72 \mu m and L=130 \mu m, we observe integer multiples n=1,2,4. At the lowest temperatures, \chi_para compensates the diamagnetic susceptibility of the \textit{whole} AgNb structure.Comment: 4 pages, 4 figures (color

    Phase Transition in Asymmetrical Superfluids I: Equal Fermi Surfaces

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    In this paper, we study phase transitions in asymmetrical fermion superfluids. In this scenario, the candidates to form pair are particles with mismatched masses and chemical potentials. We derive an expression for the critical temperature in terms of the gap and masses (or chemical potentials) when the constraint of equal Fermi surfaces maμa=mbμbm_a\mu_a = m_b\mu_b is imposed.Comment: RevTex, 11 pages, 2 figures, typos corrected and an appendix added, accepted for publication in Phys. Rev.

    Sickle cell disease in Bahia, Brazil: the social production of health policies and institutional neglect

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    A disease is considered neglected when it is not given due priority in health policies despite the social relevance of that disease, either in terms of the number of individuals affected by it or its morbidity or mortality. Although the causes are structural, neglect in health does not occur in a vacuum. In this paper, we explore how sickle cell disease (SCD) is constructed and neglected in Brazil, based on insights from our long-term participatory qualitative research in the state of Bahia. We present five overarching themes relevant to the social production of SCD, and associated health policies in Brazil: (1) The achievements and setbacks to overcome neglect in SCD, (2) Continuity of comprehensive SCD care; (3) Social movements of people with SCD; (4) Biocultural citizenship; and (5) Academic advocacy. We conclude that it is insufficient to merely recognize the health inequities that differentiate white and black populations in Brazil; racism must be understood as both a producer and a reproducer of this process of neglect. We conclude with a set of recommendations for the main SCD stakeholder groups committed to improving the lives of people living with SCD

    Symmetries and Ambiguities in the linear sigma model with light quarks

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    We investigate the role of undetermined finite contributions generated by radiative corrections in a SU(2)×SU(2)SU(2)\times SU(2) linear sigma model with quarks. Although some of such terms can be absorbed in the renormalization procedure, one such contribution is left in the expression for the pion decay constant. This arbitrariness is eliminated by chiral symmetry.Comment: 9 pages. Added references through the text; an author was added due to an important contribution; corrected typos; the title also was changed. Submitted to Modern Physics Letter
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