990 resultados para Compact Dwarf Galaxies


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The study aimed to determine an optimum angle for the nozzles axial-flow sprayers a deposition for better vertical distribution focused on cashew. In laboratory tests were conducted adjusting the angle of the nozzle axial-flow sprayers. The experimental design was randomized blocks in a 2x3 factorial with four replications. The treatment for this test were two settings (with and without the adjustment of the angles of the nozzles ) and tree application volumes 273, 699 and 954 L ha-¹.The study was conducted in an orchard of dwarf cashew, with eight years of age. It was concluded that the volumetric distribution profile showed better vertical distribution uniformity when the angles of the nozzles were regulated for the canopy, the adjustment of the angles of the nozzles for the canopy provided greater deposition of droplets, the increased volume of application resulted in higher depositions in the leaves of the crop.

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Water and fertilizer among the production factors are the elements that most restrict the production of cashew. The precise amount of these factors is essential to the success of the crop yield. This research aimed to determine the best factor-product ratio and analyze technical and economic indicators, of productivity of the cashew clone BRS 189 (Anacardium occidentale) to production factors water and potassium. The experiment was conducted from May 2009 to December 2009 in an experimental area of 56.0 m x 112.0 m in the irrigated Curu - Pentecoste, located in the municipality of Pentecoste, Ceará, Brazil. Production factors water (W) and potassium (K) were the independent variables and productivity (Y), the dependent variable. Ten statistical models that have proven satisfactory for obtaining production function were tested. The marginal rate of substitution was obtained through the ratio of the potassium marginal physical product and the water marginal physical product. The most suited model to the conditions of the experiment was the quadratic polynomial without intercept and interaction. Considering that the price of the water was 0.10 R$ mm -1, the price of the potassium 2.19 R$ kg -1 and the price of the cashew 0.60 R$ kg-1, the amounts of water and K2O to obtain the maximum net income were 6,349.1 L plant-1 of water and 128.7 g plant -1year, -1 respectively. Substituting the values obtained in the production function, the maximum net income was achieved with a yield of 7,496.8 kg ha-1 of cashew.

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This dissertation presents studies on the environments of active galaxies. Paper I is a case study of a cluster of galaxies containing BL Lac object RGB 1745+398. We measured the velocity dispersion, mass, and richness of the cluster. This was one of the most thorough studies of the environments of a BL Lac object. Methods used in the paper could be used in the future for studying other clusters as well. In Paper II we studied the environments of nearby quasars in the Sloan Digital Sky Survey (SDSS). We found that quasars have less neighboring galaxies than luminous inactive galaxies. In the large-scale structure, quasars are usually located at the edges of superclusters or even in void regions. We concluded that these low-redshift quasars may have become active only recently because the galaxies in low-density environments evolve later to the phase where quasar activity can be triggered. In Paper III we extended the analysis of Paper II to other types of AGN besides quasars. We found that different types of AGN have different large-scale environments. Radio galaxies are more concentrated in superclusters, while quasars and Seyfert galaxies prefer low-density environments. Different environments indicate that AGN have different roles in galaxy evolution. Our results suggest that activity of galaxies may depend on their environment on the large scale. Our results in Paper III raised questions of the cause of the environment-dependency in the evolution of galaxies. Because high-density large-scale environments contain richer groups and clusters than the underdense environments, our results could reflect smaller-scale effects. In Paper IV we addressed this problem by studying the group and supercluster scale environments of galaxies together. We compared the galaxy populations in groups of different richnesses in different large-scale environments. We found that the large-scale environment affects the galaxies independently of the group richness. Galaxies in low-density environments on the large scale are more likely to be star-forming than those in superclusters even if they are in groups with the same richness. Based on these studies, the conclusion of this dissertation is that the large-scale environment affects the evolution of galaxies. This may be caused by different “speed” of galaxy evolution in low and high-density environments: galaxies in dense environments reach certain phases of evolution earlier than galaxies in underdense environments. As a result, the low-density regions at low redshifts are populated by galaxies in earlier phases of evolution than galaxies in high-density regions.

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Three egg-type stocks segregating dwarf (dw) and bantam (dwB) genes in female progeny were produced from the same 18 heterozygous (dwB/dw) sires used to inseminate dams of three different genotypes: normal (dw+), dwarf (dw) and bantam (dwB) dams. The heritability of 8-week body weight estimated from full-sibs of the same phenotype of progeny was 0.40, and that estimated from paternal half-sibs of the same phenotype (dwarf or bantam), and from the same genotype of dam was 0.38. Therefore, maternal and non-additive effects within genotypic classes of dam made little contribution to the genetic variance for 8-week body weight among their progeny. The interaction of sires (S) with genotypes (dw+, dw and dwB) of dam (G) was significant at the 5% level. This indicates that the rankings of the sires within each one of the three genotypes of dam were not the same, probably due to non-additive genetic variation among genotypes of dams. The evidence indicated that in general the genes from individual sires combined differently with each type of dam (G). Those genes which combined well with the genes from normal (dw+) dams combined poorly with both the genes from the dwarf (dw) and the genes from the bantam (dwB) dams. The interaction of sires (S) with phenotypes (dwarf and bantam) of progeny (P) was significant at the 10% level. The results indicated a probable gene x genotype interaction for 8-week weight between genes at the dwarf locus (dw and dwB) and the background genotype (single and/or polygenes). The correlation among paternal half-sibs was influenced more by the S x G than by the S x P interaction, but the effects tended to be cumulative

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The present study describes the production of stocks segregating dwarf (dw), bantam (dwB) and normal (dw+) alleles, as well as the characters, shank length, adult body weight, age at sexual maturity and egg production. Heterozygous K dw+/k dwB sires were mated to normal (dw+) dams to produce stock D6.a, and mated to dwB females to produce stock D6.b. Stock D4.a came from mating F1 heterozygous dwB dw sires to dwarf Leghorns. In a third series of matings, 7/8 Sebright and 1/8 dw-Leghorn dwB dw sires were crossed to three groups of dams of different genotypes. The progeny of the normal (dw+), dwarf (dw), and bantam (dwB) dams were designated as stocks D4.b, D4.c and D4.d, respectively. The dw+ dams were White Leghorn strain cross females. The difference between the rate of laying of normal (69.7%) and their bantam sisters (68.6%) was not statistically significant when the average 32-week body weight of the dw+ sisters was 1,897 g. However, when the 32-week body weight of the normal daughters from the same sires and smaller dams was around 1,646 g, the difference between the rate of laying of the normal (78.1%) and their bantam sisters (75.9%) was significant (P < 0.05). The dwB gene may have a similar but smaller effect on the rate of egg laying than its dwarf allele. The difference between sexual maturity of normal and bantam daughters of either the largest or the smallest dams was not statistically significant, even though the smallest dwB pullets were in average 2.9 days older at first egg. The use of shank length combined with adult body weight allowed a precise discrimination between bantams and dwarfs

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Les pulsateurs compacts sont des étoiles présentant des variations intrinsèques de luminosité dont les gravités de surface sont supérieures à 100,000 cm/s² On retrouve parmi ces objets deux familles des sous-naines chaudes de type B (sdB) pulsantes et quatre familles distinctes de naines blanches pulsantes. Dans le but d'observer les pulsations de tels objets pour ensuite analyser leur propriétés grâce à l'astéroséismologie, l'Université de Montréal, en collaboration avec le Imaging Technology Laboratory (ITL - University of Arizona), a développé la caméra Mont4K (Montreal4K) CCD qui est, depuis le printemps 2007, le principal détecteur employé au télescope Kuiper de 1.55 m du Mt Bigelow (Steward Observatory, University of Arizona). à l'aide de ce montage, des observations ont été menées pour quelques-uns de ces pulsateurs compacts. La première cible fut HS 0702+6043, un pulsateur hybride. Une importante mission pour cet objet, réalisée du 1er novembre 2007 au 14 mars 2008, a permis d'identifier 28 modes de pulsations pour cet objet en plus de mettre en évidence pour certains de ces modes d'importantes variations d'amplitude. Deux autres cibles furent les naines blanches pulsantes au carbone de type « Hot DQ » SDSS J220029.08-074121.5 et SDSS J234843.30-094245.3. Il fut possible de montrer de façon indirecte la présence d'un fort champ magnétique à la surface de J220029.08-074121.5 grâce à la présence de la première harmonique du mode principal. En outre, pour ces deux cibles, on a pu conclure que celles-ci font bel et bien partie de la classe des naines blanches pulsantes au carbone.

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Un nouveau contrôleur de EMCCD (Electron multiplying Charge Coupled Device) est présenté. Il permet de diminuer significativement le bruit qui domine lorsque la puce EMCCD est utilisé pour du comptage de photons: le bruit d'injection de charge. À l'aide de ce contrôleur, une caméra EMCCD scientifique a été construite, caractérisée en laboratoire et testée à l'observatoire du mont Mégantic. Cette nouvelle caméra permet, entre autres, de réaliser des observations de la cinématique des galaxies par spectroscopie de champ intégral par interférométrie de Fabry-Perot en lumière Ha beaucoup plus rapidement, ou de galaxies de plus faible luminosité, que les caméras à comptage de photon basées sur des tubes amplificateurs. Le temps d'intégration nécessaire à l'obtention d'un rapport signal sur bruit donné est environ 4 fois moindre qu'avec les anciennes caméras. Les applications d'un tel appareil d'imagerie sont nombreuses: photométrie rapide et faible flux, spectroscopie à haute résolution spectrale et temporelle, imagerie limitée par la diffraction à partir de télescopes terrestres (lucky imaging), etc. D'un point de vue technique, la caméra est dominée par le bruit de Poisson pour les flux lumineux supérieurs à 0.002 photon/pixel/image. D'un autre côté, la raie d'hydrogène neutre (HI) à 21 cm a souvent été utilisée pour étudier la cinématique des galaxies. L'hydrogène neutre a l'avantage de se retrouver en quantité détectable au-delà du disque optique des galaxies. Cependant, la résolution spatiale de ces observations est moindre que leurs équivalents réalisés en lumière visible. Lors de la comparaison des données HI, avec des données à plus haute résolution, certaines différences étaient simplement attribuées à la faible résolution des observations HI. Le projet THINGS (The HI Nearby Galaxy Survey a observé plusieurs galaxies de l'échantillon SINGS (Spitzer Infrared Nearby Galaxies Survey). Les données cinématiques du projet THIGNS seront comparées aux données cinématiques obtenues en lumière Ha, afin de déterminer si la seule différence de résolution spatiale peut expliquer les différences observées. Les résultats montrent que des différences intrinsèques aux traceurs utilisées (hydrogène neutre ou ionisé), sont responsables de dissemblances importantes. La compréhension de ces particularités est importante: la distribution de la matière sombre, dérivée de la rotation des galaxies, est un test de certains modèles cosmologiques.

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Mémoire numérisé par la Division de la gestion de documents et des archives de l'Université de Montréal

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Mémoire numérisé par la Division de la gestion de documents et des archives de l'Université de Montréal

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Plusieurs familles de fonctions spéciales de plusieurs variables, appelées fonctions d'orbites, sont définies dans le contexte des groupes de Weyl de groupes de Lie simples compacts/d'algèbres de Lie simples. Ces fonctions sont étudiées depuis près d'un siècle en raison de leur lien avec les caractères des représentations irréductibles des algèbres de Lie simples, mais également de par leurs symétries et orthogonalités. Nous sommes principalement intéressés par la description des relations d'orthogonalité discrète et des transformations discrètes correspondantes, transformations qui permettent l'utilisation des fonctions d'orbites dans le traitement de données multidimensionnelles. Cette description est donnée pour les groupes de Weyl dont les racines ont deux longueurs différentes, en particulier pour les groupes de rang $2$ dans le cas des fonctions d'orbites du type $E$ et pour les groupes de rang $3$ dans le cas de toutes les autres fonctions d'orbites.

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The arrow shaped microstrip antenna, which produces dual frequency dual polarisation operation with considera-ble size reduction compared to conventional patches has been reported [I]. These antennas provide greater area reduction and improved gain compared to drum shaped patches [2]. Prediction of the resonance frequency of drum shaped patches [3] and circular patches for broadband operation [4] are available in the literature. In this Letter, we propose empirical formulas for calculating the resonance frequencies of the arrow shaped microstrip antenna. These antennas can be employed for obtaining dual frequency with the same polarisation, bandwidth enhancement, circular polarisation etc. by varying its different parameters or by introducing slots. The proposed design equations provide an easier and simple way of predicting the resonant frequencies of these patches.

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A new microstrip antenna geometry with considerable reduction in size, with similar radiation characteristics to those of an equivalent rectangular patch antenna is proposed. A relationship has been suggested for fmding out the resonant frequency of the new geometry, and its validity has been established by the experimental results. Without increasing the aperture area, this geometry also offers a facility for considerably reducing the resonant frequency compared to conventional patches.