22 research outputs found

    More on deviation from bi-maximal neutrino mixing

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    We study the case of UlTU^T_l presenting the exact bi-maximal mixing form with UνU_\nu inducing the deviation from the bi-maximal mixing in the final form of the Pontecorvo-Maki-Nakagawa-Sakata neutrino mixing, UPMNS=UlTUνU_{PMNS}=U^T_l U_\nu. We will show that such possibility will lead to a democratic texture for the charged lepton mass matrix and to a neutrino mass matrix with four null entries.Comment: a scenario realizing our proposal is added, new references added, to be published in J.Phys.

    A White Paper on keV Sterile Neutrino Dark Matter

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    We present a comprehensive review of keV-scale sterile neutrino Dark Matter,collecting views and insights from all disciplines involved - cosmology,astrophysics, nuclear, and particle physics - in each case viewed from boththeoretical and experimental/observational perspectives. After reviewing therole of active neutrinos in particle physics, astrophysics, and cosmology, wefocus on sterile neutrinos in the context of the Dark Matter puzzle. Here, wefirst review the physics motivation for sterile neutrino Dark Matter, based onchallenges and tensions in purely cold Dark Matter scenarios. We then round outthe discussion by critically summarizing all known constraints on sterileneutrino Dark Matter arising from astrophysical observations, laboratoryexperiments, and theoretical considerations. In this context, we provide abalanced discourse on the possibly positive signal from X-ray observations.Another focus of the paper concerns the construction of particle physicsmodels, aiming to explain how sterile neutrinos of keV-scale masses could arisein concrete settings beyond the Standard Model of elementary particle physics.The paper ends with an extensive review of current and future astrophysical andlaboratory searches, highlighting new ideas and their experimental challenges,as well as future perspectives for the discovery of sterile neutrinos

    A White Paper on keV sterile neutrino Dark Matter

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    We present a comprehensive review of keV-scale sterile neutrino Dark Matter, collecting views and insights from all disciplines involved—cosmology, astrophysics, nuclear, and particle physics—in each case viewed from both theoretical and experimental/observational perspectives. After reviewing the role of active neutrinos in particle physics, astrophysics, and cosmology, we focus on sterile neutrinos in the context of the Dark Matter puzzle. Here, we first review the physics motivation for sterile neutrino Dark Matter, based on challenges and tensions in purely cold Dark Matter scenarios. We then round out the discussion by critically summarizing all known constraints on sterile neutrino Dark Matter arising from astrophysical observations, laboratory experiments, and theoretical considerations. In this context, we provide a balanced discourse on the possibly positive signal from X-ray observations. Another focus of the paper concerns the construction of particle physics models, aiming to explain how sterile neutrinos of keV-scale masses could arise in concrete settings beyond the Standard Model of elementary particle physics. The paper ends with an extensive review of current and future astrophysical and laboratory searches, highlighting new ideas and their experimental challenges, as well as future perspectives for the discovery of sterile neutrinos

    A White Paper on keV sterile neutrino Dark Matter

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    We present a comprehensive review of keV-scale sterile neutrino Dark Matter, collecting views and insights from all disciplines involved—cosmology, astrophysics, nuclear, and particle physics—in each case viewed from both theoretical and experimental/observational perspectives. After reviewing the role of active neutrinos in particle physics, astrophysics, and cosmology, we focus on sterile neutrinos in the context of the Dark Matter puzzle. Here, we first review the physics motivation for sterile neutrino Dark Matter, based on challenges and tensions in purely cold Dark Matter scenarios. We then round out the discussion by critically summarizing all known constraints on sterile neutrino Dark Matter arising from astrophysical observations, laboratory experiments, and theoretical considerations. In this context, we provide a balanced discourse on the possibly positive signal from X-ray observations. Another focus of the paper concerns the construction of particle physics models, aiming to explain how sterile neutrinos of keV-scale masses could arise in concrete settings beyond the Standard Model of elementary particle physics. The paper ends with an extensive review of current and future astrophysical and laboratory searches, highlighting new ideas and their experimental challenges, as well as future perspectives for the discovery of sterile neutrinos

    Sobre a forma do particípio do português e o estatuto dos traços formais On the form of portuguese past participle and the status of formal features

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    Este trabalho mostra que o português tem três tipos de formação de particípio passado, que compartilham a presença da seqüência [Vacentuada + C + V] e diferem a respeito de sua localização dentro da palavra: (A) [[...]Radical + [Vacentuada+ C + V]], para todas as conjugações, (B) [[...Vacentuada... + C]Radical + V], para 1ª conjugação, e (C) [[...Vacentuada...]Radical + C + V], para 2ª e 3ª conjugações. A proposta específica do trabalho é que há uma estrutura abstrata de traços formais subjacente tanto à forma morfofonológica quanto à interpretação semântica gramatical: aquelas formações resultam de a interpretação de particípio ser satisfeita nessas três localizações. Essa análise é uma extensão da proposta de Chomsky (1995) sobre traços formais.<br>This paper shows that Portuguese has three types of past participle formations, which share the presence of the string [stressedV + C + V] and differ with respect to its location within the word: (A) [[...]Root + [stressedV + C + V]], for all conjugations, (B) [[...stressedV...+ C]Root + V], for 1st conjugation, and (C) [[...stressed V...]Root + C + V], for 2nd and 3rd conjugations. The specific proposal of the paper is that there is an abstract structure of formal features underlying both the morphophonological form and grammatical semantic interpretation: those formations result from the participial interpretation being met at these three locations. This analysis is an extension of Chomsky's (1995) proposal about formal features

    Detection and molecular characterization of group A rotavirus from hospitalized children in Rio de Janeiro, Brazil, 2004

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    Rotavirus is a major cause of infantile acute diarrhea, causing about 440,000 deaths per year, mainly in developing countries. The World Health Organization has been recommending the assessment of rotavirus burden and strain characterization as part of the strategies of immunization programs against this pathogen. In this context, a prospective study was made on a sample of 134 children with acute diarrhea and severe dehydration admitted to venous fluid therapy in two state hospitals in Rio de Janeiro, Brazil, from February to September 2004. Rotavirus where detected by polyacrylamide gel electrophoresis (PAGE) and by an enzyme-linked immunoassay to rotavirus and adenovirus (EIARA) in 48% of the children. Positive samples for group A rotavirus (n = 65) were analyzed by reverse transcription/heminested multiplex polymerase chain reaction to determine the frequency of G and [P] genotypes and, from these, 64 samples could be typed. The most frequent G genotype was G1 (58%) followed by G9 (40%). One mixed infection (G1/G9) was detected. The only [P] genotype identified was [8]. In order to estimate the rotavirus infection frequency in children who acquired diarrhea as hospital infection in those hospitals, we studied 24 patients, detecting the pathogen in 41% of them. This data suggest that genotype G9 is an important genotype in Rio de Janeiro, with implications to the future strategies of vaccination against rotavirus, reinforcing the need of continuous monitoring of circulating strains of the pathogen, in a surveillance context

    A White Paper on keV Sterile Neutrino Dark Matter

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