Diagnosing numerical Cherenkov instabilities in relativistic plasma simulations based on general meshes

Numerical Cherenkov radiation (NCR) or instability is a detrimental effect frequently found in electromagnetic particle-in-cell (EM-PIC) simulations involving relativistic plasma beams. NCR is caused by spurious coupling between electromagnetic-field modes and multiple beam resonances. This coupling may result from the slow down of poorly-resolved waves due to numerical (grid) dispersion and from aliasing mechanisms. NCR has been studied in the past for finite-difference-based EM-PIC algorithms on regular (structured) meshes with rectangular elements. In this work, we extend the analysis of NCR to finite-element-based EM-PIC algorithms implemented on unstructured meshes. The influence of different mesh element shapes and mesh layouts on NCR is studied. Analytic predictions are compared against results from finite-element-based EM-PIC simulations of relativistic plasma beams on various mesh types.Comment: 31 pages, 20 figure

Potencial agroclimatico do Estado de Pernambuco para o cultivo da acerola.

Com base nos balancos hidricos climaticos, obtidos pelo metodo "Thornthwaite e Mather" para 125mm de retencao de agua no solo das regioes de origem e de cultivo comercial da acerola (Malpighia glabra L.) foram estabelecidos os indices-limites de disponibilidade climatica para o cultivo da especie. Com os valores climaticos de temperatura do ar e de precipitacoes mensais de 124 localidades do Estado de Pernambuco, efetuaram-se os balancos hidricos. Foi observado que nao ha limitacao termica em Pernambuco para o cultivo da planta. Maior conteudo de vitaminas C e obtido nas regioes mais quentes, sendo as zonas com aptidao hidrica plena subdividida de acordo com os valores de temperatura media anual. A aptidao hidrica foi estabelecida segundo os indices hidricos anuais (Ih). A aptidao plena foi -15 cultivo de acerola

Evaluation of microclimatic data in the mango crop for epidemiological studies.

Data of air temperature, relative humidity and wind velocity were collected inside and outside a mango orchard cv. Tommy Atkins, irrigated by microsprinklers, in order to complement epidemiological studies in Petrolina, Pernambuco State, Brazil

Embryo transfer from seropositive goats for caprine arthritis-encephalitis virus (CAEV) with birth of seronegative kid.

Abstract: The aim of this study was to determine whether recipient goats would seroconvert following transfer of embryos collected from donor goats seropositive for CAEV and if kids produced would be clinically normal and seronegative for CAEV. Four does (Saanen and Alpine), seropositive for CAEV, were used as donors, receiving superovulation treatment consisting of progestagen, cloprostenol and FSH. During estrus the donors were mated with seropositive bucks. Seven days after estrus, embryo recovery was performed by surgery. The embryos were then frozen according to the protocol of the International Embryo Transfer Society (IETS). Twelve seronegative does were used as recipients and received an estrus synchronization treatment consisting of progestagen, cloprostenol and eCG. Embryo transfer was performed seven days after synchronized estrus using the semilaparoscopy technique. Pregnancy was verified in one of twelve recipients, that remained seronegative until six months after giving birth and the kid until six months of age. The preliminary success in producing CAEV negative kids and failure of seroconversion in previously seronegative recipients in this study suggests that embryo transfer technology may offer an alternative in the prevention of CAEV transmission in goat herds as well for the utilization of genetic patrimony of seropositive goats. [Transferência de embriões de cabras soropositivas para artrite-encefalite caprina a vírus (CAEV) com nascimento de cria soronegativa]. Resumo: O objetivo deste estudo foi verificar se cabras receptoras sofreriam soroconversão após a transferência de embriões colhidos de cabras soropositivas e se as crias nascidas seriam clinicamente normais e soronegativas para CAEV. Foram utilizadas quatro cabras (Saanen e Alpina), todas soropositivas para CAEV e que receberam um tratamento superovulatório que consistiu no uso de progestágeno, cloprostenol e FSH. Durante o estro, as doadoras foram cobertas por bodes soropositivos. Sete dias após o estro, a colheita de embriões foi realizada utilizando a técnica cirúrgica. Os embriões colhidos foram congelados de acordo com o protocolo da Sociedade Internacional de Transferência de Embriões (IETS). Doze cabras soronegativas foram utilizadas como receptoras e receberam um tratamento de sincronização do estro consistindo de progestágeno, cloprostenol e eCG. A transferência de embriões foi realizada sete dias após o estro sincronizado usando a técnica de semi-laparoscopia. A gestação foi confirmada em uma das doze receptoras, a qual permaneceu soronegativa até seis meses após o parto e sua cria até os seis meses de idade. O sucesso preliminar na produção de crias soronegativas para CAEV e a não soroconversão em receptoras soronegativas sugere que a tecnologia de transferência de embriões pode oferecer uma alternativa para a profilaxia da CAEV em rebanhos caprinos, bem como para o aproveitamento do patrimônio genético de animais soropositivos

Stability of casein micelles cross-linked with genipin: a physicochemical study as a function of pH

Chemical or enzymatic cross-linking of casein micelles (CMs) increases their stability against dissociating agents. In this paper, a comparative study of stability between native CMs and CMs cross-linked with genipin (CMs-GP) as a function of pH is described. Stability to temperature and ethanol were investigated in the pH range 2.0-7.0. The size and the charge ($\zeta$-potential) of the particles were determined by dynamic light scattering. Native CMs precipitated below pH 5.5, CMs-GP precipitated from pH 3.5 to 4.5, whereas no precipitation was observed at pH 2.0-3.0 or pH 4.5-7.0. The isoelectric point of CMs-GP was determined to be pH 3.7. Highest stability against heat and ethanol was observed for CMs-GP at pH 2, where visible coagulation was determined only after 800 s at 140 $^\circ$C or 87.5% (v/v) of ethanol. These results confirmed the hypothesis that cross-linking by GP increased the stability of CMs.Comment: 5 pages, 2 figures, International Dairy Journal, 201

Estimativa e mapeamento das normais anuais de umidade relativa do ar no Estado da Paraiba.

Esse trabalho tem como objetivo a obtenção de uma equação de estimativa da umidade relativa do ar, através de dados existentes desse parâmetro e do balanço hídrico climático e o mapeamento na Paraíba, visando a utilização em estudos bioclimáticos

Geometric approach to nonvariational singular elliptic equations

In this work we develop a systematic geometric approach to study fully nonlinear elliptic equations with singular absorption terms as well as their related free boundary problems. The magnitude of the singularity is measured by a negative parameter $(\gamma -1)$, for $0 < \gamma < 1$, which reflects on lack of smoothness for an existing solution along the singular interface between its positive and zero phases. We establish existence as well sharp regularity properties of solutions. We further prove that minimal solutions are non-degenerate and obtain fine geometric-measure properties of the free boundary $\mathfrak{F} = \partial \{u > 0 \}$. In particular we show sharp Hausdorff estimates which imply local finiteness of the perimeter of the region $\{u > 0 \}$ and $\mathcal{H}^{n-1}$ a.e. weak differentiability property of $\mathfrak{F}$.Comment: Paper from D. Araujo's Ph.D. thesis, distinguished at the 2013 Carlos Gutierrez prize for best thesis, Archive for Rational Mechanics and Analysis 201

Zoneamento agroclimático da cultura da videira no Estado da Bahia.

Este estudo teve como finalidade determinar a aptidão climática das diferentes regiões do Estado da Bahia, para o cultivo da videira irrigada, como base para um programa de expansão do seu cultivo comercial no Estado