1,412 research outputs found

    Patterns of antenal sensilla of Panstrongylus megistus from three Brazilian states

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    The objective of the present study was to analyze and describe the phenotype of the antennal sensilla of Panstrongylus megistus, one of the epidemiologically most important species of triatomines in Brazil. Specimens from the Brazilian states of Goiás (GO), Minas Gerais (MG), and Rio Grande do Sul (RS) were compared, based on studies of four types of sensilla on three antennal segments: thick-walled trichoid (TK), thin-walled trichoid (TH), bristles (BR), and basiconica (BA). Discriminant analysis allowed the separation of the RS specimens from those of GO and MG. Multivariate discriminant analysis demonstrated that the sensilla of males differed from those of females, the variables with greatest weight being the BA of all three segments and the TK of flagellum 1. The basiconica sensilla were significantly more abundant in females, on all three segments. Antennal sensilla patterns also demonstrated significant differences among P. megistus specimens.Fil: Villela, M. M.. Fundación Oswaldo Cruz; BrasilFil: Catala, Silvia Susana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja. - Universidad Nacional de La Rioja. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja. - Universidad Nacional de Catamarca. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja. - Secretaría de Industria y Minería. Servicio Geológico Minero Argentino. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja. - Provincia de La Rioja. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja; ArgentinaFil: Juberg, J.. Instituto Oswaldo Cruz; Brasil. Fundación Oswaldo Cruz; BrasilFil: Silva, I. G.. Universidade Federal de Goiás; BrasilFil: Dias, J. C. P.. Fundación Oswaldo Cruz; Brasi

    Spillover and diffraction sidelobe contamination in a double-shielded experiment for mapping Galactic synchrotron emission

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    We have analyzed observations from a radioastronomical experiment to survey the sky at decimetric wavelengths along with feed pattern measurements in order to account for the level of ground contamination entering the sidelobes. A major asset of the experiment is the use of a wire mesh fence around the rim-halo shielded antenna with the purpose of levelling out and reducing this source of stray radiation for zenith-centered 1-rpm circular scans. We investigate the shielding performance of the experiment by means of a geometric diffraction model in order to predict the level of the spillover and diffraction sidelobes in the direction of the ground. Using 408 MHz and 1465 MHz feed measurements, the model shows how a weakly-diffracting and unshielded antenna configuration becomes strongly-diffracting and double-shielded as far-field diffraction effects give way to near-field ones. Due to the asymmetric response of the feeds, the orientation of their radiation fields with respect to the secondary must be known a priori before comparing model predictions with observational data. By adjusting the attenuation coefficient of the wire mesh the model is able to reproduce the amount of differential ground pick-up observed during test measurements at 1465 MHz.Comment: 14 pages, 17 eps + 1 gif figures and 4 Tables. Accepted for publication in A&AS. Fig.7 available at full resolution from http://www.das.inpe.br/~tello/publications.ht

    Alignment tests for low CMB multipoles

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    We investigate the large scale anomalies in the angular distribution of the cosmic microwave background radiation as measured by WMAP using several tests. These tests, based on the multipole vector expansion, measure correlations between the phases of the multipoles as expressed by the directions of the multipole vectors and their associated normal planes. We have computed the probability distribution functions for 46 such tests, for the multipoles l=2-5. We confirm earlier findings that point to a high level of alignment between l=2 (quadrupole) and l=3 (octopole), but with our tests we do not find significant planarity in the octopole. In addition, we have found other possible anomalies in the alignment between the octopole and the l=4 (hexadecupole) components, as well as in the planarity of l=4 and l=5. We introduce the notion of a total likelihood to estimate the relevance of the low-multipoles tests of non-gaussianity. We show that, as a result of these tests, the CMB maps which are most widely used for cosmological analysis lie within the ~ 10% of randomly generated maps with lowest likelihoods.Comment: References added, updated discussion on alignment with Ecliptic Plane. 12 Pages, 6 Figures. Results for additional maps, the normalized frequencies for the tests and a Mathematica Notebook that computes the tests can be found on http://fma.if.usp.br/~abramo/MVA.htm

    Resistência do milho (Zea mays L.) transgênico (Bt) a lagarta-do-cartucho, Spodoptera frugiperda (Smith) (Lepidoptera: Noctuidae).

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    No Brasil, a utilização de milho transgênico (Bt) pode reduzir perdas causadas por vários lepidópteros-pragas, equivalentes a aproximadamente 500 milhões de dólares anuais. O objetivo deste trabalho foi avaliar os híbridos de milho Bt disponíveis no mercado americano para resistência à lagarta-do-cartucho do milho (LCM), Spodoptera frugiperda (Smith) (Lepidoptera: Noctuidae). Nove híbridos de milho Bt expressando as toxinas Cry 1F, Cry 1A(b), Cry 1 A(c) e Cry 9C, além de um híbrido (MP 704 X 707) expressando resistência natural para a LCM, foram comparados num experimento, em campo, em blocos ao acaso, com parcela subdividida e quatro repetições. Nas parcelas, foram comparados os dez híbridos e, nas subparcelas, as versões Bt versus não-Bt, ou híbrido com resistência natural versus susceptível. A infestação artificial foi realizada 33 dias após a semeadura e as avaliações basearam-se no número de larvas sobreviventes, aos 10 e 15 dias após a infestação, peso das larvas sobreviventes e notas de danos nas plantas. Para todas as variáveis estudadas, os resultados demonstraram diferenças significativas (P=0,05) entre os híbridos avaliados. Também as testemunhas não-Bts diferiram significativamente dos respectivos híbridos Bts, exceto para aqueles expressando a toxina Cry 9C. O híbrido 2722 IMI, expressando a toxina Cry 1F, foi o mais resistente (imune) e os híbridos expressando a toxina Cry 1A(b) e a resistência natural foram moderadamente resistentes. Em geral, os híbridos transgênicos resistentes produziram cerca de 32% a mais de grãos que as testemunhas suscetíveis
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