Nematic liquid crystal dynamics under applied electric fields

In this paper we investigate the dynamics of liquid crystal textures in a two-dimensional nematic under applied electric fields, using numerical simulations performed using a publicly available LIquid CRystal Algorithm (LICRA) developed by the authors. We consider both positive and negative dielectric anisotropies and two different possibilities for the orientation of the electric field (parallel and perpendicular to the two-dimensional lattice). We determine the effect of an applied electric field pulse on the evolution of the characteristic length scale and other properties of the liquid crystal texture network. In particular, we show that different types of defects are produced after the electric field is switched on, depending on the orientation of the electric field and the sign of the dielectric anisotropy.Comment: 7 pages, 12 figure

Interaction of Anthonomus grandis and cotton genotypes: biological and behavioral responses.

The boll weevil, Anthonomus grandis Boheman (Coleoptera: Curculionidae), is a key pest of cotton, Gossypium hirsutum L. (Malvaceae). Knowledge about boll weevil feeding and oviposition behavior and its response to plant volatiles can underpin our understanding of host plant resistance, and contribute to improved monitoring and mass capture of this pest. Boll weevil oviposition preference and immature development in four cotton genotypes (CNPA TB90, TB85, TB15, and BRS Rubi) were investigated in the laboratory and greenhouse. Volatile organic compounds (VOCs) produced by TB90 and Rubi genotypes were obtained from herbivore-damaged and undamaged control plants at two phenological stages ? vegetative (prior to squaring) and reproductive (during squaring) ? and four collection times ? 24, 48, 72, and 96 h following herbivore damage. The boll weevil exhibited similar feeding and oviposition behavior across the four tested cotton genotypes. The chemical profiles of herbivore-damaged plants of both genotypes across the two phenological stages were qualitatively similar, but differed in the amount of volatiles produced. Boll weevil response to VOC extracts was studied using a Y-tube olfactometer. The boll weevil exhibited similar feeding and oviposition behavior at the four tested cotton genotypes, although delayed development and production of smaller adults was found when fed TB85. The chemical profile of herbivore-damaged plants of both genotypes at the two phenological stages and time periods (24?96 h) was similar qualitatively, with 30 identified compounds, but differed in the amount of volatiles produced. Additionally, boll weevil olfactory response was positive to herbivory-induced volatiles. The results help to understand the interaction between A. grandis and cotton plants, and why it is difficult to obtain cotton genotypes possessing constitutive resistance to this pest

Implementação do algoritmo em Matlab® do método de diagonalização filtrada para análises de sinais de ressonância magnética nuclear.

No título, em Matlab® o símbolo é sobrescrito

The influence of hot pressing on high density fibreboards, when the panels are used for overlaying

Um conjunto de painéis de fibras de alta densidade, colados com uma resina de melamina/ureia-formaldeído, foi submetido a operações de prensagem a quente, de modo a estudar a influência desta operação nas propriedades do substrato. Usou-se uma prensa de pratos, a uma pressão que permitisse um contacto firme entre os painéis e os pratos da prensa. Foi desenvolvido um plano experimental para três temperaturas diferentes de 95, 180 e 210 º C e dois tempos de prensagem, de 22 e 35 segundos, para cada uma delas. Os painéis foram fabricados com fibras de pinho (Pinus pinaster) a uma densidade média de 930 kg/m3 e espessura média de 6,7 mm De acordo com os resultados obtidos, as operações de pós-fabrico dos painéis de alta densidade resultaram numa ligeira melhoria do módulo de elasticidade, da tensão de rotura à flexão estática e da resistência interna dos painéis usados como substrato. Observou-se também uma ligeira diminuição da humidade de equilíbrio e espessura dos painéis, bem como um aumento da densidade e do inchamento, com o aumento da temperatura e tempo de prensagem.ct A series of high density fiberboard (HDF) panels, bonded with melamine/urea-formaldehyde (MUF), were exposed to a post manufacture hot pressing at various temperatures and pressing durations using a hot press and just enough pressure to ensure firm contact between the panel and the press platens. The experimental plan was developed for three different temperatures of 95, 180 and 210ºC and two different pressing times, of 22 and 35 seconds. The panels were made with pine fibers (pinus pinaster) at a target density of 930 kg/m3 and target thickness of 6.7 mm. The results indicated that the pos-manufacture hot-pressing of the exterior HDF panels resulted in a slightly improvement of the modulus of elasticity (MOE), bending strength and internal bonding (IB) of the panels used as substrates. A reduction in moisture content and thickness as well as an increase in density and thickness swelling was also noticed with an increase in the temperature and pressing timeinfo:eu-repo/semantics/publishedVersio

Eletroantenograma para estudo comportamental de insetos.

bitstream/CNPDIA-2009-09/11834/1/CT74_2006.pd

Degradation analysis in the estimation of photometric redshifts from non-representative training sets

We perform an analysis of photometric redshifts estimated by using a non-representative training sets in magnitude space. We use the ANNz2 and GPz algorithms to estimate the photometric redshift both in simulations as well as in real data from the Sloan Digital Sky Survey (DR12). We show that for the representative case, the results obtained by using both algorithms have the same quality, either using magnitudes or colours as input. In order to reduce the errors when estimating the redshifts with a non-representative training set, we perform the training in colour space. We estimate the quality of our results by using a mock catalogue which is split samples cuts in the $r$-band between $19.4< r< 20.8$. We obtain slightly better results with GPz on single point z-phot estimates in the complete training set case, however the photometric redshifts estimated with ANNz2 algorithm allows us to obtain mildly better results in deeper $r$-band cuts when estimating the full redshift distribution of the sample in the incomplete training set case. By using a cumulative distribution function and a Monte-Carlo process, we manage to define a photometric estimator which fits well the spectroscopic distribution of galaxies in the mock testing set, but with a larger scatter. To complete this work, we perform an analysis of the impact on the detection of clusters via density of galaxies in a field by using the photometric redshifts obtained with a non-representative training set.Comment: 19 pages, 9 figures. Accepted for publication in MNRA

Atividades de quitinase após eliciação das defesas da soja contra a ferrugem asiática.

Para avaliar a influência do jasmonato de metila (JM) sobre a atividade da quitinase (proteína relacionada à patogênese), assim como, o potencial do eliciador na redução do progresso da ferrugem asiática, no estádio V5 as plantas da cultivar suscetível BRS 361 foram pulverizadas com água, Tween 20 a 0,02 % e JM a 1,25 mM. Após 24 horas da pulverização, as plantas foram inoculadas com 1,4x105 uredósporos/mL de Phakopsora pachyrhizi; como controle foi aplicado água. Utilizou-se delineamento em blocos ao acaso, com seis blocos, cada vaso contendo cinco plantas. Coletaram-se folhas V4 e V5, às 48, 96, 144 e 192 horas após a inoculação. Folhas de plantas não inoculadas foram coletadas nos mesmos períodos. A atividade da quitinase foi determinada pelo método proposto por Robert & Selitrennikoff (Journal of General Microbiology, v. 134, n. 1, p. 169-176, 1988), modificado por Harman et al. (Phytopathology, v. 83, n. 3, p. 313-318, 1993). A atividade da quitinase foi superior em folhas de soja inoculadas em comparação com as não inoculadas, independente dos produtos aplicados. A aplicação de JM aumentou a atividade da quitinase em folhas submetidas ou não a inoculação, independente do período de avaliação. A aplicação de Tween 20 também aumentou a atividade em comparação com a água, independente da inoculação, embora com intensidade sempre menor que o JM. Os resultados obtidos sugerem que a inoculação com ferrugem asiática da soja induz a atividade da quitinase e que eliciadores JM e Tween 20 podem ser usados para avaliar a resistência da soja ao patógeno