Generation of higher derivatives operators and electromagnetic wave propagation in a Lorentz-violation scenario

We study the perturbative generation of higher-derivative operators as corrections to the photon effective action, which are originated from a Lorentz violation background. Such corrections are obtained, at one-loop order, through the proper-time method, using the zeta function regularization. We focus over the lowest order corrections and investigate their influence in the propagation of electromagnetic waves through the vacuum, in the presence of a strong, constant magnetic field. This is a setting of experimental relevance, since it bases active efforts to measure non linear electromagnetic effects. After surprising cancellations of Lorentz violating corrections to the Maxwell's equation, we show that no effects of the kind of Lorentz violation we consider can be detected in such a context.Comment: v2: 13 pages, no figures, section IV considerably rewritten, main results unchanged and are now obtained in a simpler way. To appear in PL

Descrição das larvas das principais espécies de peixes utilizadas pela pesca, no Pantanal.

Elaborou-se uma chave ilustrada, baseando-se na comparacao de caracteristicas morfologicas e morfometricas dos estadios iniciais, quando as larvas ainda sao encontradas no plancton, a deriva no rio. A chave possui a descricao das cinco principais especies utilizadas economicamente no Pantanal: pacu (Piaractus mesopotamicus), curimbata (Prochilodus lineatus), dourado (Salminus maxillosus), piavucu (Leporinus macrocephalus). As especies pintado (Pseudoplatystoma corruscans) e cachara (Pseudoplatystoma fasciatum), por nao apresentarem nenhuma diferenca nas caracteristicas utilizadas nas descricoes, foram incluidas em Pseudoplatystoma sp. As descricoes foram feitas a partir de amostras obtidas em condicoes artificiais.bitstream/item/37433/1/BP19.pd

Distribuicao espacial do tucunare, Cichla sp (Pisces, cichlidae), peixe amazonico introduzido no Pantanal, Brasil.

O tucunare, uma especie exotica, introduzido da bacia Amazonica, tem sido observado no Pantanal desde 1982 no Rio Piquiri, na divisa dos estados de Mato Grosso e Mato Grosso do Sul. Entre novembro de 1992 e janeiro de 1994 foram realizadas 5 campanhas ao longo da bacia do rio Piquiri e no rio Sao Lourenco, acima e abaixo da sua juncao com o rio Piquiri. Exemplares de tucunare foram encontrados em lagos marginais, sugerindo que possivelmente utilizam o rio somente como "corredor". Os limites da distribuicao foram definidos como: 17o28'59"S, 55o13'45"O (abertura da passagem subterranea do rio Correntes); 17o21'20"S, 54o30'25"O (cachoeira Itiquira); 17o18'44"S, 56o43'24"O (boca do rio Piquiri). Portanto, ocorrendo somente na bacia do Piquiri. A transparencia (medida atraves do disco de Secchi) do rio Sao Lourenco e menor que a do rio Piquiri, (22 e 39 cm, e 50 e 70 cm, respectivamente). A baixa transparencia e o reduzido numero de ambientes lenticos, o habitat preferencial das especies, e a longa distancia entre os mesmos no rio Sao Lourenco, podem estar atuando como uma barreira a dispersao do tucunare.bitstream/item/37428/1/BP24.pd

Alimentacao do tucunare Cichla sp. (Pisces, cichlidae) um peixe introduzido no Pantanal, Brasil.

Com o objetivo de estudar a alimentacao do tucunare (Cichla sp.) no Pantanal, foram realizadas cinco coletas entre novembro/1992 e junho/1994. Foram capturados 425 especimes, destes 207 apresentaram conteudo estomacal. Foram analisadas a Frequencia de Ocorrencia (FO), Volume Relativo (Vr) e "Indice Alimentar" (IA). Os peixes foram o principal item alimentar (FO=97,10%, Vr=96,45, IAi=99,81%), seguido de "restos vegetais", (FO=6,28%, Vr=2,49, IAi=16%) e camaroes (FO=1,93%, Vr=1,04, IAi=2%). Foram identificadas 21 especies de peixes no conteudo estomacal do "tucunare". Curimatella dorsalis foi a presa predominante em numero de individuos (18,75%) e em biomassa (28,81%). A familia mais representativa em biomassa foi Curimatidae (27,36%) e Cichlidae (26,93%); em numero de individuos, Sternopygidae foi mais representada (26,66%), seguida de Cichlidae e Curimatidae, com 15,55%. Os resultados permitem caracterizar o tucunare como piscivoro generalista.bitstream/item/37429/1/BP23.pd

Experimental and theoretical evidences for the ice regime in planar artificial spin ices

In this work, we explore a kind of geometrical effect in the thermodynamics of artificial spin ices (ASI). In general, such artificial materials are athermal. Here, We demonstrate that geometrically driven dynamics in ASI can open up the panorama of exploring distinct ground states and thermally magnetic monopole excitations. It is shown that a particular ASI lattice will provide a richer thermodynamics with nanomagnet spins experiencing less restriction to flip precisely in a kind of rhombic lattice. This can be observed by analysis of only three types of rectangular artificial spin ices (RASI). Denoting the horizontal and vertical lattice spacings by a and b, respectively, then, a RASI material can be described by its aspect ratio $\gamma$=a/b. The rhombic lattice emerges when $\gamma$=$\sqrt{3}$. So, by comparing the impact of thermal effects on the spin flips in these three appropriate different RASI arrays, it is possible to find a system very close to the ice regime

Regularized quantile regression for SNP marker estimation of pig growth curves.

Background: Genomic growth curves are generally defined only in terms of population mean; an alternative approach that has not yet been exploited in genomic analyses of growth curves is the Quantile Regression (QR). This methodology allows for the estimation of marker effects at different levels of the variable of interest. We aimed to propose and evaluate a regularized quantile regression for SNP marker effect estimation of pig growth curves, as well as to identify the chromosome regions of the most relevant markers and to estimate the genetic individual weight trajectory over time (genomic growth curve) under different quantiles (levels). Results: The regularized quantile regression (RQR) enabled the discovery, at different levels of interest (quantiles), of the most relevant markers allowing for the identification of QTL regions. We found the same relevant markers simultaneously affecting different growth curve parameters (mature weight and maturity rate): two (ALGA0096701 and ALGA0029483) for RQR(0.2), one (ALGA0096701) for RQR(0.5), and one (ALGA0003761) for RQR(0.8). Three average genomic growth curves were obtained and the behavior was explained by the curve in quantile 0.2, which differed from the others. Conclusions: RQR allowed for the construction of genomic growth curves, which is the key to identifying and selecting the most desirable animals for breeding purposes. Furthermore, the proposed model enabled us to find, at different levels of interest (quantiles), the most relevant markers for each trait (growth curve parameter estimates) and their respective chromosomal positions (identification of new QTL regions for growth curves in pigs). These markers can be exploited under the context of marker assisted selection while aiming to change the shape of pig growth curves

Calibration and validation of models for short-term decomposition and N mineralization.

Insight of nutrient release patterns associated with the decomposition of plant residues is important for their effective use as a green manure in food production systems. Thus, this study aimed to evaluate the ability of the Century, APSIM and NDICEA simulation models for predicting the decomposition and N mineralization of crop residues in the tropical Atlantic forest biome, Brazil. The simulation models were calibrated based on actual decomposition and N mineralization rates of three types of crop residues with different chemical and biochemical composition. The models were also validated for different pedo-climatic conditions and crop residues conditions. In general, the accuracy of decomposition and N mineralization improved after calibration. Overall RMSE values for the decomposition and N mineralization of the crop materials varied from 7.4 to 64.6 % before models calibration compared to 3.7 to 16.3 % after calibration. Therefore, adequate calibration of the models is indispensable for use them under humid tropical conditions. The NDICEA model generally outperformed the other models. However, the decomposition and N mineralization was not very accurate during the first 30 days of incubation, especially for easily decomposable crop residues. An additional model variable may be required to capture initial microbiological growth as affected by the moisture dynamics of the residues, as is the case in surface residues decomposition model

Estratégias ambientais em grandes empresas com atividade galvânica no Rio Grande do Sul.

As pressões sociais sinalizam que os custos para adequação da empresa às demandas do meio ambiente podem se transformar em conscientização, pois a sociedade não mais aceita a exacerbação do lucro obtido às custas dos efeitos ambientais negativos. Assim, a proteção ambiental deixou de ser uma função exclusiva da produção para ser uma função da empresa, fazendo parte da estrutura organizacional e do planejamento estratégico. As empresas que possuem processos galvânicos são consideradas de alto impacto ambiental, devido ao grande consumo de água, energia, geração de emissões e resíduos sólidos perigosos. Conciliar a atividade produtiva com a sustentabilidade ambiental é um desafio enfrentado pelas empresas. Este contexto determinou o problema da pesquisa: qual o tipo e o foco das estratégias ambientais adotadas pelas grandes empresas do Rio Grande do Sul com atividade galvânica para o controle dos impactos negativos? O objetivo do trabalho foi identificar tipos de estratégias implantadas pelas empresas pesquisadas. Para a realização da pesquisa foi usado o método investigativo, a partir do estudo de caso em cinco grandes empresas. O estudo de caso permitiu identificar o potencial das empresas gaúchas para a implantação de estratégias preventivas que possibilitam reduzir perdas e a poluição ambiental

REVIEW OF CFD SIMULATION OF OXY-COAL COMBUSTION FOR ELETRICAL POWER GENERATION: OPPORTUNITIES AND CHALLENGES

The oxy-combustion has generated significant interested for reduction of CO2 emission when the fossil fuel is coal, due to simplification on the separation process of CO2 from the flue gas, it can be more easily stored in reservoir. The CFD numerical simulation techniques in oxy-coal combustion has the potential to contribute to designers in cost savings and reduced computational time; Furthermore, such techniques also provide a robust tool for better understanding and description of the aerothermodynamics processes involved, as well as, aiding the design of most efficient furnaces. However, to obtain representative results of the physical phenomena, the numerical models employed by CFD needs to be suitable for oxy-coal combustion. So, the aim of the paper is to carry out a review of the recent models that are being used for turbulence, combustion and pollutant emissions. Moreover, it is shown a comparison of different results obtained in the numerical simulation of oxy-coal combustion among new models, existing models and experiments. The analysis of the models and experiments shows that the challenges that are still being faced to obtain better accuracy of numerical simulation results. Improvements in the models for oxy-coal combustion can be seen like potential opportunities to investigate and optimize the process that occur in the combustion