1,233 research outputs found
Methods for Removing Urea and Preventing Discoloration During Processing of Dehydrated Salted Shark.
A polymorphism associated with depressive disorders differentially regulates brain derived neurotrophic factor promoter IV activity
PMCID: PMC3712170Peer reviewedPublisher PD
Decomposing the Sources of Earnings Inequality: Assessing the Role of Reallocation
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/93733/1/irel697.pd
Exploring nu signals in dark matter detectors
We investigate standard and non-standard solar neutrino signals in direct
dark matter detection experiments. It is well known that even without new
physics, scattering of solar neutrinos on nuclei or electrons is an irreducible
background for direct dark matter searches, once these experiments each the ton
scale. Here, we entertain the possibility that neutrino interactions are
enhanced by new physics, such as new light force carriers (for instance a "dark
photon") or neutrino magnetic moments. We consider models with only the three
standard neutrino flavors, as well as scenarios with extra sterile neutrinos.
We find that low-energy neutrino--electron and neutrino--nucleus scattering
rates can be enhanced by several orders of magnitude, potentially enough to
explain the event excesses observed in CoGeNT and CRESST. We also investigate
temporal modulation in these neutrino signals, which can arise from geometric
effects, oscillation physics, non-standard neutrino energy loss, and
direction-dependent detection efficiencies. We emphasize that, in addition to
providing potential explanations for existing signals, models featuring new
physics in the neutrino sector can also be very relevant to future dark matter
searches, where, on the one hand, they can be probed and constrained, but on
the other hand, their signatures could also be confused with dark matter
signals.Comment: 38 pages, 8 figures, 1 table; v3: eq 3 and nuclear recoil plots
corrected, footnote added, conclusions unchange
Tri-Bimaximal Lepton Mixing and Leptogenesis
In models with flavour symmetries added to the gauge group of the Standard
Model the CP-violating asymmetry necessary for leptogenesis may be related with
low-energy parameters. A particular case of interest is when the flavour
symmetry produces exact Tri-Bimaximal lepton mixing leading to a vanishing
CP-violating asymmetry. In this paper we present a model-independent discussion
that confirms this always occurs for unflavoured leptogenesis in type I see-saw
scenarios, noting however that Tri-Bimaximal mixing does not imply a vanishing
asymmetry in general scenarios where there is interplay between type I and
other see-saws. We also consider a specific model where the exact Tri-Bimaximal
mixing is lifted by corrections that can be parametrised by a small number of
degrees of freedom and analyse in detail the existing link between low and
high-energy parameters - focusing on how the deviations from Tri-Bimaximal are
connected to the parameters governing leptogenesis.Comment: 29 pages, 6 figures; version 2: references added, minor correction
Modelo para Mensuração de Projetos de Circuitos Lógicos em Atividades Acadêmicas
Avaliando o tempo e a complexidade de circuitos, o artigo propõe uma métrica para análise de desempenho dos mesmos. O foco dessa pesquisa consiste em propor um modelo que sirva de auxílio ao aluno para concepção de um novo circuito e disponibilização de um feedback sobre a solução proposta
Heteroskedasticity testing through a comparison of Wald statistics
This paper shows that a test for heteroskedasticity within the context of classical linear regression can be based on the difference between Wald statistics in heteroskedasticity-robust and nonrobust forms. The test is asymptotically distributed under the null hypothesis of homoskedasticity as chi-squared with one degree of freedom. The power of the test is sensitive to the choice of parametric restriction used by the Wald statistics, so the supremum of a range of individual test statistics is proposed. Two versions of a supremum-based test are considered: the first version does not have a known asymptotic null distribution, so the bootstrap is employed to approximate its empirical distribution. The second version has a known asymptotic distribution and, in some cases, is asymptotically pivotal under the null. A simulation study illustrates the use and finite-sample performance of both versions of the test. In this study, the bootstrap is found to provide better size control than asymptotic critical values, namely with heavy-tailed, asymmetric distributions of the covariates. In addition, the use of well-known modifications of the heteroskedasticity consistent covariance matrix estimator of OLS coefficients is also found to benefit the tests’ overall behaviour.info:eu-repo/semantics/publishedVersio
Neutrino Mixings and the S4 Discrete Flavour Symmetry
Discrete non-Abelian Symmetries have been extensively used to reproduce the
lepton mixings. In particular, the S4 group turned out to be suitable to
describe predictive mixing patterns, such as the well-known Tri-Bimaximal and
the Bimaximal schemes, which all represent possible first approximations of the
experimental lepton mixing matrix. We review the main application of the S4
discrete group as a flavour symmetry, first dealing with the formalism and
later with the phenomenological implications. In particular, we summarize the
main features of flavour models based on S4, commenting on their ability in
reproducing a reactor angle in agreement with the recent data and on their
predictions for lepton flavour violating transitions.Comment: 33 pages, 7 figures, 4 tables. Review written for the special issue
on "Flavor Symmetries and Neutrino Oscillations", published in Fortschritte
der Physik - Progress of Physic
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