Mass for Plasma Photons from Gauge Symmetry Breaking

We derive the effective masses for photons in unmagnetized plasma waves using a quantum field theory with two vector fields (gauge fields). In order to properly define the quantum field degrees of freedom we re-derive the classical wave equations on light-front gauge. This is needed because the usual scalar potential of electromagnetism is, in quantum field theory, not a physical degree of freedom that renders negative energy eigenstates. We also consider a background local fluid metric that allows for a covariant treatment of the problem. The different masses for the longitudinal (plasmon) and transverse photons are in our framework due to the local fluid metric. We apply the mechanism of mass generation by gauge symmetry breaking recently proposed by the authors by giving a non-trivial vacuum-expectation-value to the second vector field (gauge field). The Debye length $\lambda_D$ is interpreted as an effective compactification length and we compute an explicit solution for the large gauge transformations that correspond to the specific mass eigenvalues derived here. Using an usual quantum field theory canonical quantization we obtain the usual results in the literature. Although none of these ingredients are new to physicist, as far as the authors are aware it is the first time that such constructions are applied to Plasma Physics. Also we give a physical interpretation (and realization) for the second vector field in terms of the plasma background in terms of known physical phenomena. Addendum: It is given a short proof that equation (10) is wrong, therefore equations (12-17) are meaningless. The remaining results are correct being generic derivations for nonmagnetized plasmas derived in a covariant QFT framework.Comment: v1: 1+6 pages v2: Several discussions rewritten; Abstract rewritten; References added; v3: includes Addendu

On fermion masses and mixing in a model with A4A_4 symmetry

In a recently proposed multi-Higgs extension of the standard model in which discrete symmetries, $A_4$ and $Z_3$ are imposed we show that, after accommodating the fermion masses and the mixing matrices in the charged currents, the mixing matrices in the neutral currents induced by neutral scalars are numerically obtained. However, the flavor changing neutral currents are under control mainly by mixing and/or mass suppressions in the neutral scalar sector.Comment: Version accepted for publication in International Journal of Modern Physics A. In this version we added a discussion on the charged lepton and neutrino masses. The title has been changed. Other minor changes do not modify the conclusion

INTERNATIONAL AND INSTITUTIONAL R&D SPILLOVERS: ATTRIBUTION OF BENEFITS AMONG SOURCES FOR BRAZIL'S NEW CROP VARIETIES

In general, reported rates of return to agricultural R&D are high, but questions have been raised about upward biases in the evidence. Among the reasons for this bias, insufficient attention to attribution aspects-matching of research benefits and costs-is a pervasive problem, the magnitude of which is illustrated here with new evidence for Brazil. Over the period 1981 to 2003, varietal improvements in upland rice, edible beans, and soybeans yielded benefits attributable to research of $14.8 billion in present value (1999 prices) terms; 6.1 percent of the corresponding value of crop output. If all of those benefits were attributed to Embrapa, a public research corporation accounting for more than half Brazil's agricultural R&D spending, the benefit-cost ratio would be 78:1. If a geometric attribution rule based on genetic histories is used in conjunction with quantitative evidence on the extent of research collaborations to account for the innovative effort of others, the ratio drops substantially to 16:1 (or an internal rate of return of 38.7 percent). The sources of these gains vary markedly among crops and over time, making it hard to generalize about the international and institutional origins of varietal innovations in Brazilian agriculture during the past several decades.Brazil, agricultural R&D, attribution, soybeans, rice, beans, benefit-cost ratios, Crop Production/Industries, Research and Development/Tech Change/Emerging Technologies,

Psychometric Properties of the Barrier Autoinform for the Practice of the Physical Exercise (ABPEF)

El estudio consistió en examinar las propiedades psicométricas del cuestionario de autoinforme de barreras para la práctica del ejercicio físico (ABPEF) y comprobar el efecto del género sobre dichas barreras. Se han estudiado sus propiedades psicométricas con una muestra de 342 adolescentes (media de edad: 15.02±1.86). Se realizaron análisis de confiabilidad, análisis factorial exploratorio, correlación ítem con puntaje total y análisis factorial confirmatorio. Se encuentra una buena confiabilidad interna (α = .86), adecuada correlación ítem con puntaje total, y la presencia de cuatro factores en el análisis factorial exploratorio con correlaciones significativas entre las mismas. El análisis factorial confirmatorio mostró adecuado ajuste a los datos de un modelo tetrafactorial del cuestionario (χ2 /gl = 3.696; GFI=.89; AGFI=.86; RMSEA=.061). El género femenino presenta mayores barreras para la práctica del ejercicio físico. Este cuestionario es un instrumento fiable y válido y se sugiere su uso en futuras investigacionesThe objective of this study was to examine the psychometric properties of the self-report questionnaire for physical exercise (ABPEF). And to chek the effect of gender on those barriers. Their psychometric properties were studied with a sample of 342 adolescents (mean age: 15.02 ± 1.86). We performed reliability analysis, exploratory factor analysis, item correlation with total score and confirmatory factor analysis. We found a good internal reliability (α = .86), an adequate item correlation with total score, and the presence of four factors in the exploratory factor analysis with significant correlations between them. The confirmatory factor analysis showed adequate adjustment to the data of a tetrafactorial model of the questionnaire (χ2 / gl = 3.696; GFI = .89; AGFI = .86; RMSEA = .061). The female gender presents greater barriers to the practice of physical exercise. This questionnaire is a reliable and valid instrument for the population under study, and its use in future research is suggeste

Conformal Orbifold Partition Functions from Topologically Massive Gauge Theory

We continue the development of the topological membrane approach to open and unoriented string theories. We study orbifolds of topologically massive gauge theory defined on the geometry $[0,1]\times\Sigma$, where $\Sigma$ is a generic compact Riemann surface. The orbifold operations are constructed by gauging the discrete symmetries of the bulk three-dimensional field theory. Multi-loop bosonic string vacuum amplitudes are thereby computed as bulk correlation functions of the gauge theory. It is shown that the three-dimensional correlators naturally reproduce twisted and untwisted sectors in the case of closed worldsheet orbifolds, and Neumann and Dirichlet boundary conditions in the case of open ones. The bulk wavefunctions are used to explicitly construct the characters of the underlying extended Kac-Moody group for arbitrary genus. The correlators for both the original theory and its orbifolds give the expected modular invariant statistical sums over the characters.Comment: 47 pages LaTeX, 3 figures, uses amsfonts and epsfig; v2: Typos corrected, reference added, clarifying comments on modular invariance inserted; v3: Further comments on modular invariance added; to be published in JHE

Surface tension implementation for Gensmac 2D

In the present work we describe a method which allows the incorporation of surface tension into the GENSMAC2D code. This is achieved on two scales. First on the scale of a cell, the surface tension effects are incorporated into the free surface boundary conditions through the computation of the capillary pressure. The required curvature is estimated by fitting a least square circle to the free surface using the tracking particles in the cell and in its close neighbors. On a sub-cell scale, short wavelength perturbations are filtered out using a local 4-point stencil which is mass conservative. An efficient implementation is obtained through a dual representation of the cell data, using both a matrix representation, for ease at identifying neighbouring cells, and also a tree data structure, which permits the representation of specific groups of cells with additional information pertaining to that group. The resulting code is shown to be robust, and to produce accurate results when compared with exact solutions of selected fluid dynamic problems involving surface tension

Numerical and experimental investigations of three-dimensional container filling with Newtonian viscous fluids

This work employs numerical and experimental approaches to investigate three-dimensional container filling with Newtonian viscous fluids. For this purpose, a computer code developed for simulating three-dimensional free surface flows has been used. The CFD Freeflow3D code was specifically designed to deal with unsteady three-dimensional flows possessing multiple moving free surfaces. An experimental apparatus that allows the visualization of the various phenomena that can occur during the filling of containers has been constructed and employed. Experiments on container filling were carried out by varying the fluid velocity at the injection nozzle. This paper presents a computational study on container filling with Newtonian viscous fluids and employs the experimental results to validate the software. The experimental observations were compared with the predictions from the Freeflow3D code and good agreement between the two sets of results is observed. Moreover, the code predictions showed that it is capable of capturing the most relevant phenomena observed in the experiments.The Brazilian authors would like to acknowledge the financial support given by the funding agencies: CNPq - Conselho Nacional de Desenvolvimento Cientifico e Tecnologico (Grant Nos. 302631/2010-0, 301408/2009-2, 472514/2011-3), FAPESP - Fundacao de Amparo a Pesquisa do Estado de Sao Paulo (Grant No. 2011/13930-0) and CAPES Grant Nos. BEX 2844/10-9 and 226/09 (CAPES-FCT). This work is part of the activities developed within the CEPID-CeMEAI FAPESP project Grant No. 2013/07375 - 0 and also benefits from the early collaboration within the framework of the University of Sao Paulo (Brazil) and University of Porto (Portugal) research agreements. The Portuguese authors gratefully acknowledge funding from Fundacao para a Ciencia e Tecnologia (FCT) under the project PEst-C/CTM/LA0025/2013 (Strategic Project - LA 25-2013-2014), project PTDC/MAT/121185/2010 and FEDER, via FCT

Influência de diferentes sítios de crescimento sobre a qualidade da madeira de Pinus taeda.

O presente trabalho analisa os efeitos de diferentes sítios de crescimento na qualidade da madeira de Pinus taeda, além de testar a técnica não-destrutiva de aplicação de ondas de tensão para estimativa das características da madeira. Foram analisados três sítios com árvores de 14, 16 e 18 anos de idade. Para a caracterização do sítio, foram coletadas amostras de solo indeformadas e compostas. Em cada sítio foram selecionadas cinco árvores. Com elas ainda em pé, foram realizadas medições do tempo de propagação de ondas de tensão. Também foram medidos a altura total e comercial e o diâmetro à altura do peito, e retirados discos em cinco posições ao longo do fuste. Posteriormente, nas toras recém-abatidas, efetuaram-se novamente as medições do tempo de propagação das ondas de tensão, além de serem coletadas acículas do terço médio da copa de cada árvore. De maneira geral, as madeiras provenientes de sítios com taxa de crescimento elevado apresentaram maiores valores para massa específica, fibras mais curtas, mais largas, com diâmetros maiores e paredes mais espessas ? conseqüentemente, maiores valores para índice de Runkel e fração parede e menores valores para coeficiente de flexibilidade e índice de enfeltramento. Correlações significativas foram detectadas, indicando que a técnica não-destrutiva pode ser empregada para determinação indireta dessas características