Neutrino dispersion relation in a magnetized multi-stream matter background

We study the propagation of a neutrino in a medium that consists of two or more thermal backgrounds of electrons and nucleons moving with some relative velocity, in the presence of a static and homogeneous electromagnetic field. We calculate the neutrino self-energy and dispersion relation using the linear thermal Schwinger propagator, we give the formulas for the dispersion relation and discuss general features of the results obtained, in particular the effects of the stream contributions. As a specific example we discuss in some detail the case of a magnetized two-stream electron, i.e., two electron backgrounds with a relative velocity $\vec v$ in the presence of a magnetic field. For a neutrino propagating with momentum $\vec k$, in the presence of the stream the neutrino dispersion relation acquires an anisotropic contribution of the form $\hat k\cdot\vec v$ in addition to the well known term $\hat k\cdot\vec B$, as well as an additional contribution proportional to $\vec B\cdot\vec v$. We consider the contribution from a nucleon stream background as an example of other possible stream backgrounds, and comment on possible generalizations to take into account the effects of inhomogeneous fields. We explain why a term of the form $\hat k\cdot(\vec v\times\vec B)$ does not appear in the dispersion relation in the constant field case, while a term of similar form can appear in the presence of an inhomogeneous field involving its gradient.Comment: Title changed, 21 pages, 1 figur

Cultivos consorciados de cafeeiro arábica: caracterização morfológica, fisiológica e nutricional

FObjetivou-se nesta pesquisa caracterizar a morfologia, fisiologia e nutrição do cafeeiro arábica (Coffea arabica L.) sob três sistemas de condução: monocultivo, consorciado com bananeira e consorciado com bananeira e palmeira juçara. O estudo foi desenvolvido na localidade de Lagoa Seca, município de Alegre-ES, em lavoura de cafeeiro arábica, cultivar Catuaí Vermelho IAC 44. As variáveis analisadas no experimento formam: a) atributos físicos e químicos do solo; b) características morfológicas (arquitetura de copa, morfologia e partição de biomassa de ramos plagiotrópicos, razão de rendimento, produtividade e tamanho dos grãos); c) características fisiológicas (concentração de clorofilas e trocas gasosas); e d) características nutricionais (teores de macro e micronutrientes em folhas, ramos e frutos e conteúdo de nutrientes por compartimento do ramo plagiotrópico) do cafeeiro. Foi possível verificar que o solo cultivado com cafeeiro em condições de monocultivo apresentou melhores características químicas (pH, P, K, Ca, Mg, SB, t, V e m). As plantas em monocultivo alocaram mais massa seca e nutrientes nos grãos; apresentaram maiores teores foliares para P, K, Ca, S, Cu e Zn; foram mais eficientes no uso de água (A/gs; A/E); e foram mais produtivas. Nos sistemas consorciados, as plantas de cafeeiro expuseram maior diâmetro de copa; maior alocação de massa seca e nutrientes nas folhas e caules dos ramos plagiotrópicos; exibiram maior proporção de grãos graúdos (peneira 16 acima); apresentaram maior condutância estomática; exibiram maiores teores foliares para Mg e Fe; alocaram mais nutrientes nas folhas e caules

Crystallographic Oxide Phase Identification of Char Deposits Obtained from Space Shuttle Columbia Window Debris

Analyzing the remains of Space Shuttle Columbia has proven technically beneficial years after the vehicle breakup. This investigation focused on charred deposits on fragments of Columbia overhead windowpanes. Results were unexpected relative to the engineering understanding of material performance in a reentry environment. The TEM analysis demonstrated that the oxides of aluminum and titanium mixed with silicon oxides to preserve a history of thermal conditions to which portions of the vehicle were exposed. The presence of Ti during the beginning of the deposition process, along with the thermodynamic phase precipitation upon cool down, indicate that temperatures well above the Ti melt point were experienced. The stratified observations implied that additional exothermic reaction, expectedly metal combustion of a Ti structure, had to be present for oxide formation. Results are significant for aerospace vehicles where thermal protection system (TPS) breaches cause substructures to be in direct path with the reentry plasma.

Muscle mass measured using bioelectrical impedance analysis, calf circumference and grip strength in older adults

AbstractObjectiveTo determine the correlation between muscle mass, measured using bioelectrical impedance analysis (BIA), with calf circumference and grip strength.Materials and methodsCross-sectional and observational study. Including all functional adults over 60 years of age seen in our Geriatric Clinic during the months of March 2013–February 2014. Measurements of weight, height, BMI, calf circumference, grip strength and muscle mass by BIA were made after the signature of informed consent.Results105 patients were evaluated, 73 women and 32 men, with a mean age of 76 years (SD±7.3). Muscle mass showed a mild positive correlation with calf circumference: Pearson (r=0.31; p=0.000) and a moderate positive correlation with grip strength: Pearson (r=0.50; p=0.000).DiscussionMuscle mass by BIA has a positive correlation with calf circumference and grip strength, and is a reliable measure to assess muscle mass and physical performance in older adults in geriatric ambulatory clinics and can be used in the diagnosis of sarcopenia in Mexican patients

Plutonium pit manufacturing unit process separation options for rapid reconstitution, a joint position paper of Lawrence Livemore National Laboratory and Los Alamos National Laboratory

This document addressed technical issues regarding the manufacturing processes involved in making plutonium pits. It addresses acceptable approaches from a technical standpoint as to how the manufacturing processes can be separated and distributed among different manufacturing sites. Site selections, costs, and intra-site transfers are not addressed in this document

Academic freedom in Europe: time for a Magna Charta?

This paper is a preliminary attempt to establish a working definition of academic freedom for the European Union states. The paper details why such a definition is required for the European Union and then examines some of the difficulties of defining academic freedom. By drawing upon experience of the legal difficulties beset by the concept in the USA and building on previous analyses of constitutional and legislative protection for academic freedom, and of legal regulations concerning institutional governance and academic tenure, a working definition of academic freedom is then derived. The resultant definition which, it is suggested, could form the basis for a European Magna Charta Libertatis Academicae, goes beyond traditional discussions of academic freedom by specifying not only the rights inherent in the concept but also its accompanying duties, necessary limitations and safeguards. The paper concludes with proposals for how the definition might be tested and carried forward