8,821 research outputs found

    Charge and Magnetic Flux Correlations in Chern-Simons Theory with Fermions

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    Charge and magnetic flux bearing operators are introduced in Chern-Simons theory both in its pure form and when it is coupled to fermions. The magnetic flux creation operator turns out to be the Wilson line. The euclidean correlation functions of these operators are shown to be local and are evaluated exactly in the pure case and through an expansion in the inverse fermion mass whenever these are present. Physical states only occur in the presence of fermions and consist of composite charge-magnetic flux carrying states which are in general anyonic. The large distance behavior of the correlation functions indicates the condensation of charge and magnetic flux.Comment: Latex, 17 page

    Supersymmetric free-damped oscillators: Adaptive observer estimation of the Riccati parameter

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    A supersymmetric class of free damped oscillators with three parameters has been obtained in 1998 by Rosu and Reyes through the factorization of the Newton equation. The supplementary parameter is the integration constant of the general Riccati solution. The estimation of the latter parameter is performed here by employing the recent adaptive observer scheme of Besancon et al., but applied in a nonstandard form in which a time-varying quantity containing the unknown Riccati parameter is estimated first. Results of computer simulations are presented to illustrate the good feasibility of this approach for a case in which the estimation is not easily accomplished by other meansComment: 8 pages, 6 figure

    Dataset of ideological polarization in Western Europe

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    This dataset provides data on ideological polarization in Western Europe. It is based on parties’ left-right placement provided by several expert surveys. Then, it uses Dalton’s polarization index (2008) to calculate the polarization score in terms of votes and seats for each election. The dataset covers 20 Western European countries since 1945, for a total of 398 parliamentary elections and legislatures (Lower House). The dataset will be regularly updated to include the polarization scores of new elections and legislatures

    Evidence of the inhomogeneity of the stellar population in the differentially reddened globular cluster NGC 3201

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    We report on evidence of the inhomogeneity (multiplicity) of the stellar population in the Galactic globular cluster (GC) NGC 3201, which is irregularly reddened across its face. We carried out a more detailed and careful analysis of our recently published new multi-color photometry in a wide field of the cluster with particular emphasis on the U band. Using the photometric data corrected for differential reddening, we found for the first time two key signs of the inhomogeneity in the cluster's stellar population and of its radial variation in the GC. These are (1) an obvious trend in the color-position diagram, based on the (U-B) color-index, of red giant branch (RGB) stars, which shows that the farther from the cluster's center, the bluer on average the (U-B) color of the stars is; and (2) the dependence of the radial distribution of sub-giant branch (SGB) stars in the cluster on their U magnitude, where brighter stars are less centrally concentrated than their fainter counterparts at a confidence level varying between 99.2% and 99.9% depending on the color-index used to select the stars. The same effects were recently found by us in the GC NGC 1261. However, contrary to NGC 1261, we are not able to unambiguously suggest which of the sub-populations of SGB/RGB stars can be the progenitor of blue and red horizontal branch stars of the cluster. Apart from M4, NGC 3201 is another GC very probably with an inhomogeneous stellar population, which has essentially lower mass than the most massive Galactic GCs where multiple stellar populations were unambiguously detected for the first timeComment: 5 pages, 4 figure

    Impacto do aumento da concentração de CO2 atmosférico sobre a microbiota do solo rizosférico de arroz.

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    A intensificação da atividade antrópica está causando significativo aumento da concentração de dióxido de carbono (CO2) na atmosfera, resultando em alterações no clima do planeta que devem ser acentuadas nas próximas décadas. Além das mudanças climáticas previstas, impactos também ocorrerão no ambiente biótico. O trabalho teve por objetivo avaliar os efeitos do aumento do CO2 atmosférico na microbiota do solo rizosférico de arroz (cultivar Agulha Precoce), em ensaio conduzido em estufas de topo aberto. Os tratamentos com injeção automatizada do gás apresentaram concentração média de 613 ppm de CO2. Como testemunha, foram utilizadas parcelas sem estufa e sem injeção do gás. Não houve efeito dos tratamentos no carbono da biomassa microbiana, na hidrólise de diacetato de fluoresceína, no desprendimento de CO2 e na condutividade elétrica do solo rizosférico e no número de bactérias diazotróficas endofíticas isoladas das raízes utilizando-se meio de cultura JNFb semi-específico para Herbaspirillum. Os tratamentos com estufa apresentaram aumento do pH do solo, sendo que o maior aumento foi obtido no tratamento com injeção de CO2

    Strong low-frequency quantum correlations from a four-wave mixing amplifier

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    We show that a simple scheme based on nondegenerate four-wave mixing in a hot atomic vapor behaves like a near-perfect phase-insensitive optical amplifier, which can generate bright twin beams with a measured quantum noise reduction in the intensity difference of more than 8 dB, close to the best optical parametric amplifiers and oscillators. The absence of a cavity makes the system immune to external perturbations, and the strong quantum noise reduction is observed over a large frequency range.Comment: 4 pages, 4 figures. Major rewrite of the previous version. New experimental results and further analysi

    A metacognitive model of self-esteem

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    Background: In the current study, we aimed to test a metacognitive model of self-esteem grounded in the Self-Regulatory Executive Function model of psychopathology. Method: A convenience sample of 346 community participants were recruited and completed a battery of online questionnaires that measured self-esteem, self-criticism, self-critical rumination, metacognitions about self-critical rumination, generic metacognitions and negative affect. Initially, we tested a series of hypotheses to establish the relationships between the study variables. We then examined whether self-critical rumination, and its associated metacognitions, both positive and negative, would independently predict self-esteem when controlling for age, negative affect, levels of self-criticism and generic metacognitions. Results: Self-critical rumination and its associated negative metacognitions, levels of depression and self-criticism independently predicted self-esteem. Additionally, a path analysis revealed that the study data was a very good fit to the proposed metacognitive model of self-esteem. Conclusion: The metacognitive model of self-esteem presented in this paper may be used to generate novel interventions to improve self-esteem and decrease self-critical rumination
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