989 resultados para 726
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Este estudo foi conduzido para avaliar os efeitos dos níveis de lisina digestível da ração e da temperatura ambiente sobre o desempenho e as características de carcaça de frangos de corte dos 22 a 42 dias de idade. Foram utilizados 672 frangos Ross®, machos, com peso médio de 726 g, em delineamento inteiramente casualizado segundo arranjo fatorial 4 × 4, com seis repetições de sete aves. Os frangos foram mantidos nas temperaturas de 18,5; 21,1; 24,5 e 27,0ºC e foram alimentados com rações com diferentes níveis de lisina digestível (0,934; 1,009; 1,084 e 1,159%). Não houve interação temperatura ambiente × níveis de lisina da ração para as variáveis estudadas. O consumo de ração (CR) e o ganho de peso (GP) não foram influenciados pelos níveis de lisina. O consumo de ração reduziu linearmente com a temperatura ambiente e o ganho de peso aumentou até a temperatura estimada de 21,5ºC. A conversão alimentar melhorou até o nível estimado de 1,085% de lisina digestível. Os pesos de carcaça (PC), peito com osso (PPO), coxa (PCX) e sobrecoxa (PSCX) aumentaram até as temperaturas estimadas de 21,9; 21,0; 22,7 e 23,7ºC, respectivamente. Os rendimentos de carcaça (RC), coxa (RCX) e sobrecoxa (RSCX) aumentaram, enquanto o peso do peito sem osso (PPSO) e os rendimentos de peito com osso (RPO) e sem osso (RPSO) reduziram linearmente com a temperatura ambiente. O PCX e o RCX aumentaram, mas o RSCX reduziu linearmente com os níveis de lisina da ração. O PC, PPO, PSCX, RC, RPO e o RPSO não foram influenciados pelos níveis de lisina. A temperatura ambiente no intervalo de 18,5 e 27,0ºC não influenciou as exigências de lisina das aves. A condição para melhor conversão alimentar no período de 22 a 42 dias foi obtida com o nível de 1,085% de lisina digestível na ração e com a temperatura ambiente estimada de 23,3ºC.
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Two cases treated for hypertrophy of the frontal sinus are presented. In both patients, the excised frontal bone was inverted, and the resultant cavity was filled with either bone dust from the parietal region or Medpor. The first patient is shown with an excellent result after a follow-up period of 16 years. The second patient, who also achieved an excellent result, is presented after a follow-up period of 5 years. Using Medpor instead of bone dust resulted in the advantage that the operation could be performed with the patient under local anesthesia with sedation and prevention of an additional donor site. The use of Medpor has certain advantages over the use of hydroxyapatite, not least of which is its significant lower cost.
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The nonlinear refractive index, n(2), of films based on the new glass system Sb(2)O(3)-Sb(2)S(3) was measured at 1064 nm with laser pulses of 15 ps, using a single-beam nonlinear image technique in presence of a phase object. The films were prepared from bulk glasses by RF-sputtering. A large value of n(2) = 3 x 10-(15) m(2)/W, which is three orders of magnitude larger than for CS(2), was determined. The result shows the strong potential of antimony-sulfide glass films for integrated nonlinear optics. (c) 2005 Elsevier B.V. All rights reserved.
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Laboratory time-scale experiments were conducted on Carboniferous Limestone gravels from the Mendip Hills area, England, with the purpose of evaluating the release of Rn-222 to the water phase. The specific surface areas of the samples were 4.14 and 1.69 cm g(-1), which provided, respectively, values of 50.6 and 12.7 pCi for the released Rn. These results allowed the calculation of the emanation coefficient of this rock matrix with respect to the release of Rn, where completely different values corresponding to 23% and 6% were found, suggesting that the extent to which grain boundaries or imperfections in aggregates of micro-crystals of calcite intersect the particle surface certainly affects the Rn release. They also permitted the evaluation of models for the generation of Rn in rocks and transfer to water, in order to interpret the radioactivity due to this gas in groundwaters from the karstic aquifer of the Mendip Hills area, where the calculated activities in groundwater based on the values of 23% and 6% for the emanation coefficient were about 51 and 15 times higher than actually measured in groundwater. Therefore, the emanation coefficient in nature is considerably smaller than in the lab experiment, and another factor k (0 < k < 1) may be introduced into the equations related to the modelling, with the aim of adjusting the theoretical-practical results. (C) 1997 Elsevier B.V. Ltd. All rights reserved.
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This paper presents a new model for the representation of electrodes' filaments of hot-cathode fluorescent lamps, during preheating processes based on the injection of currents with constant root mean square (rms) values. The main improvement obtained with this model is the prediction of the R-h/R-c ratio during the preheating process, as a function of the preheating time and of the rms current injected in the electrodes. Using the proposed model, it is possible to obtain an estimate of the time interval and the current that should be provided by the electronic ballast, in order to ensure a suitable preheating process. is estimate of time and current can be used as input data in the design of electronic ballasts with programmed lamp start, permitting the prediction of the R-h/R-c ratio during the initial steps of the design (theoretical analysis and digital simulation). Therefore, the use of the proposed model permits to reduce the necessity of several empirical adjustments in the prototype, in order to set the operation of electronic ballasts during the preheating process. This fact reduces time and costs associated to the global design procedure of electronic ballasts.
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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This paper presents the analysis of a dc-ac converter using a zero-voltage-switching (ZVS) commutation cell. First, we show the cell applied to the buck converter. The stages of operation are presented along with the main current and voltage equations. Next, we adapt the converter to the regenerative-operation mode. Hence, the full-bridge converter at low-frequency operation is connected in the dc-dc output stage (at high frequency). The main switches commute at zero voltage. The converter operated at constant frequency with pulse-width modulation (PWM), and neither overvoltage nor additional current stress was observed by digital simulation. A design example and experimental results obtained by prototype, rated at 275 V and 1 kW, are also presented. © 1997 IEEE.
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The magnetic and structural properties of sol-gel derived organic/inorganic nanocomposites doped with Fe(II), Fe(III), Nd(III) and Eu (III) ions are discussed. These hybrids consist of poly(oxyethylene)-based chains grafted onto siloxane nanodomains by urea cross-linkages. Small angle X-ray scattering data show the presence of spatial correlations of siloxane domains embedded in the polymer matrix. The magnetic properties of rare-earth doped samples are determined by single ion crystal-field-splitted levels (Eu3+ J=0; Nd3+ J=9/2) and the small thermal irreversibility is mainly associated to structural effects. Fe2+ -doped samples behave as simple paramagnet with residual antiferromagnetic interactions. Fe3+-doped hybrids are much more complex, with magnetic hysterisis, exchange anisotropy and thermal irreversibility at low temperatures. Néel temperatures increase up to 14K for the highest (∼5.5%) Fe3+ mass concentration.
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In this study we describe and quantify the brood care performed by workers in queenless colonies of the leaf-cutting ant Acromyrmex subterraneus brunneus. Fifteen behavioral acts were recorded in the three colonies studied. The behavioral repertoire of males was more limited, with only four behavioral acts being observed: feeding through workers, collecting staphylae and self-feeding, mutual grooming between adults (worker-males), and self-grooming. Males were also found to be able to collect food (staphylae or fungal hyphae) from the fungus garden and to feed themselves, not requiring workers for this activity. This study contributes to a better understanding of the basic biology of leaf-cutting ant colonies, with the description and quantification of the activities performed by the members of a colony in a situation of the loss of the fertile caste.
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Two new flavone glucosides, nitensosides A and B (1, 2), together with four known compounds, sorbifolin (3), sorbifolin 6-O-β-glucopyranoside (4), pedalitin (5), and pedalitin 6-O-β-glucopyranoside (6) were isolated from Pterogyne nitens. Their structures were elucidated from 1D and 2D NMR analysis, as well as by high resolution mass spectrometry. All the isolated flavones were evaluated for their myeloperoxidase (MPO) inhibitory activity. The most active compound, pedalitin, exhibited IC 50 value of 3.75 nM on MPO. Additionally, the radical-scavenging capacity of flavones 1-6 was evaluated towards ABTS and DPPH radicals and compared to standard compounds quercetin and Trolox®. © 2008 Pharmaceutical Society of Japan.
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