1,234 research outputs found

    Radiatively induced leptogenesis in a minimal seesaw model

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    We study the possibility that the baryon asymmetry of the universe is generated in a minimal seesaw scenario where two right-handed Majorana neutrinos with degenerate masses are added to the standard model particle content. In the usual framework of thermal leptogenesis, a nonzero CPCP asymmetry can be obtained through the mass splitting induced by the running of the heavy Majorana neutrino masses from their degeneracy scale down to the seesaw scale. Although, in the light of the present neutrino oscillation data, the produced baryon asymmetry turns out to be smaller than the experimental value, the present mechanism could be viable in simple extensions of the standard model.Comment: 6 pages, 2 figures, uses RevTeX4, calculations improved, comments adde

    Hidden Genetic Variability, Can the Olive Moth Prays oleae (Lepidoptera: Yponomeutidae or Praydidae?) be a Species’ Complex?

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    Prays oleae is the second most important pest in Mediterranean olive groves, causing substantial damage on olive production. We used mitochondrial [cytochrome c oxidase subunit I (COI), and NADH dehydrogenase subunit 5 (nad5)] and nuclear [ribosomal protein S5 (RpS5)] amplicons to assess the population variability in five main olive producing regions from Tunisia, to support or dismiss the existence of two non-monophyletic groups within the species, as found within Portugal. Our phylogenetic analysis with cytochrome c oxidase subunit I (COI) indeed displayed two distinct and well-supported clades of P. oleae, which were corroborated by the haplotype network reconstructed with both mitochondrial and nuclear amplicons. We were also able to dismiss the hypothesis that one of the clades would not develop on olive fruits. No correlation was observed between clades differentiation and geographic distribution. The existence of cryptic species can impact on the management of agroecosystems and on the perception of how these moths responds to environmental changes

    Thermostatistics of overdamped motion of interacting particles

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    We show through a nonlinear Fokker-Planck formalism, and confirm by molecular dynamics simulations, that the overdamped motion of interacting particles at T=0, where T is the temperature of a thermal bath connected to the system, can be directly associated with Tsallis thermostatistics. For sufficiently high values of T, the distribution of particles becomes Gaussian, so that the classical Boltzmann-Gibbs behavior is recovered. For intermediate temperatures of the thermal bath, the system displays a mixed behavior that follows a novel type of thermostatistics, where the entropy is given by a linear combination of Tsallis and Boltzmann-Gibbs entropies.Comment: 4 pages, 2 figure

    A Bridge between CP violation at Low Energies and Leptogenesis

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    We discuss the possibility of relating the size and sign of the observed baryon asymmetry of the universe to CP violation observable at low energies, in a framework where the observed baryon asymmetry is produced by leptogenesis through the out of the equilibrium decay of heavy Majorana neutrinos. We identify the CP violating phases entering in leptogenesis as well as those relevant for CP violation at low energies in the minimal seesaw model. We show that although in general there is no relation between these two sets of phases, there are specific frameworks in which such a connection may be established and we give a specific grand unification inspired example where such a connection does exist. We construct weak-basis invariants related to CP violation responsible for leptogenesis, as well as those relevant for CP violation at low energies

    Construindo a identidade agroecológica através de trocas de experiências entre assentamentos da reforma agrária no estado de São Paulo.

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    Resumo: Este trabalho faz parte do projeto ?Capacitação sócio-ambiental para construção de projetos de desenvolvimento sustentável em assentamentos rurais no estado de São Paulo?, uma parceria da Embrapa Meio Ambiente com o INCRA, MST e outras organizações de agricultores assentados. Assim, propomos apresentar uma etapa dos trabalhos que vem sendo desenvolvido nos assentamentos Itapeva e Sepé Tiaraju, nos respectivos municípios de Itapeva/SP e Ribeirão Preto/SP. Iniciado em 2009, este trabalho visa a assessorar e potencializar os trabalhos de transição agroecológica através da aproximação de agricultores assentados com processos diferentes de ocupação da terra, porém com mesmos objetivos de diversificação do sistema produtivo de forma sustentável. Abstract: This work is part of the project "Capacity building for social and environmental projects for sustainable development in rural settlements in the state of São Paulo, a partnership withEmbrapa Environment INCRA, MST and other organizations offarmers settled.Therefore, we propose to present a step in the work being donein the settlements and Itapeva Sepe Tiaraju, in their municipality of Itapeva / SP, Ribeirao Preto / SP. Started in 2009, this work aims to assist and enhance the work through the transitionalagro- ecological approach to resettled farmers with different processes acupaçao of the earth, but with the same objectivesof diversification of the productive system in a sustainable manner

    Exploring the relationship between ethical and sustainable consumption in short supply chains: A literature review

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    Sustainable development, sustainable consumption and short supply chains are nowadays acquiring increasing relevance in the literature. On the other hand, from the consumer's attitudinal statement, ethical consumption is also requiring more attention from marketing sciences. Besides that, the integration of the last concept on sustainability remains in a complete lack of systematic and integrative conceptualization. This paper tries to promote a potential integration of all the dimensions of sustainable consumption and to understand the potential linkage and interaction among them, in order to promote the Sustainable Development Goal 15 from the United Nations. The methodology follows a systematic literature review and preliminary information comes from a case study of the approved project SDGsConsum. The results confirm that, besides a huge development in sustainable development and sustainable consumption in the literature, the focus on shortly supply chains of production is yet modest. Moreover, the motivations and constraints that drive and restrain, respectively, consumers toward ethical and sustainable consumption presents several incongruences.info:eu-repo/semantics/acceptedVersio

    Nonlinear Relativistic and Quantum Equations with a Common Type of Solution

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    Generalizations of the three main equations of quantum physics, namely, the Schr\"odinger, Klein-Gordon, and Dirac equations, are proposed. Nonlinear terms, characterized by exponents depending on an index qq, are considered in such a way that the standard linear equations are recovered in the limit q1q \rightarrow 1. Interestingly, these equations present a common, soliton-like, travelling solution, which is written in terms of the qq-exponential function that naturally emerges within nonextensive statistical mechanics. In all cases, the well-known Einstein energy-momentum relation is preserved for arbitrary values of qq
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