73 resultados para 817


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The strange morphology of the F ring of Saturn is thought to be caused by the perturbing effects of two close satellites, Prometheus and Pandora. The F ring and the satellites also experience periodic close encounters as a result of differential precession arising from Saturn's oblateness. Using the orbits of the F-ring strands derived by Murray et al. (1997, Icarus 129, 304-316) the behaviour of the ring particles at their closest approach to Prometheus is analysed using numerical simulations. The results show that a gap and a wave are formed in the ring at each encounter with the satellite. However, the gap is expected to have a short lifetime due to keplerian shear. © 2000 Elsevier Science Ltd. All rights reserved.

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In this work we analyze the convergence of solutions of the Poisson equation with Neumann boundary conditions in a two-dimensional thin domain with highly oscillatory behavior. We consider the case where the height of the domain, amplitude and period of the oscillations are all of the same order, and given by a small parameter e > 0. Using an appropriate corrector approach, we show strong convergence and give error estimates when we replace the original solutions by the first-order expansion through the Multiple-Scale Method.

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In this work, a silica surface chemically modified with [3-(2,2′-dipyridylamine)propyl] groups, named [3-(2,2′- dipyridylamine)propyl]silica (Si-Pr-DPA) was prepared, characterized, and evaluated for its heavy metal adsorption characteristics from aqueous solution. To our knowledge, we are the first authors who have reported the present modification. The material was characterized using infrared spectroscopy, SEM, and NMR 29Si and 13C solid state. Batch and column experiments were conducted to investigate for heavy metal removal from dilute aqueous solution by sorption onto Si-Pr-DPA. From a number of studies the affinity of various metal ions for the Si-Pr-DPA sorbent was determined to follow the order Fe(III) > Cr(III) >> Cu(II) > Cd(II) > Pb(II) > Ni(II). Two standard reference materials were used for checking the accuracy and precision of the method. The proposed method was successfully applied to the analysis of environmental samples. This ligand material has great advantage for adsorption of transition-metal ions from aqueous medium due to its high degree of organofunctionalization associated with the large adsorption capacity, reutilization possibility, and rapidity in reaching the equilibrium. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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This work describes an electronic system implementation with two force plates, 24 load cells with strain gages, signal conditioning circuit, interfacing circuit and data acquisition system, designed for measuring plantar force distribution in patients. The system presented linear response, low hysteresis, with determination coefficient of 0.9997, precision better than 0,84% and resolution less than 0.5 N. The Measurements are presented on a computer screen and easier visualization to specialists, mainly physicians, physiotherapists and occupational therapists. Using the system, the distribution of weight in the plantar region of 100 normal subjects and 10 hemiplegic patients was investigated. There were determined the relationship between weight distribution on the right and left forefoot, hemiplegic patients and normal patients, with the implemented system. © 2013 Springer.

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The aim of this study was to determine the variation of the temperature after shearing in sheep under dry and hot environment conditions and to compare the temperature changes with variation in cardiac and respiratory frequencies, ruminal movements and hydration status. Twenty Suffolk unshorn ewes were studied. Physical examination was performed in all animals three times a day at 7:00 AM, 1:00 PM and 7:00 PM, during 42 days (22 days before shearing and 20 days after shearing). The skin temperature was measured by infrared thermometer over several surfaces of the body. Data were submitted to analysis of variance, for comparisons between groups (shorn versus unshorn) at each time, and the significant difference was evaluated at level of P<0.05 by Tukey test. The respiratory frequency was statistically significant at all times. When air humidity was high, the respiratory frequencies were low. The thermal stress was clear in sheep of this study, reflecting marked changes in cardiac and respiratory frequencies and rectal temperature. The respiratory frequency was the parameter more reliable to establish a framework of thermal stress in the unshorn sheep, with values on average three times higher than those reported in the literature. The heart rate monitors the thermal variation of the environment and is also an indicator of heat stress. This variation shows the Suffolk breed is well adapted to hot climates. The correlation between the body surface temperatures with environment temperature and air humidity was negative, as explained by the effect of wool insulation, i.e. even with an increase in environment temperature and humidity, the body temperature tends to maintain a compensating balance. In the shorn animals, the correlation between skin temperature with environment temperature and air humidity showed that the skin temperature increases when the environment temperature increases. The increase in the environment temperature does not affect the body temperature of unshorn animals due the insulating effect of the wool. However, when environment temperature rises, the presence of the wool starts to affect the thermal comfort as the heat absorption is larger than the capacity of heat loss. In this study, the best thermal stress indicators were the respiratory frequency and rectal and skin temperatures. The temperatures of the skin measured at the perineum, axillae and inner thigh were considered the most reliable.

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Pós-graduação em Ciências Cartográficas - FCT

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Pós-graduação em Geologia Regional - IGCE

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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Pós-graduação em Zootecnia - FMVZ

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Pós-graduação em Ciências Biológicas (Zoologia) - IBB

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The Brazilian campos rupestres (high-altitude grasslands) are very important on the world conservation scenario because of high species richness and endemism. These grasslands are regarded as threatened ecosystems due to intense, on-going disruption by man's activities. The aim of this study was to describe the reproductive and vegetative phenological patterns of six shrub species endemic to these grasslands in the Espinhaço Range, sympatric in Serra do Cipó, MG. We tested the relationship between species phenophases and local climate seasonality. We expect that the species phenophases are strongly correlated with variations of the dry and wet seasons. Observations were conducted monthly on reproductive (flowering, fruit production and dispersal) and vegetative (leaf fall and budding) phenophases. Given the combination of reproductive phenology, vegetative phenology, and seasonality, we observed four phenological strategies for the six species. Therefore this study revealed great diversity in phenological patterns, even when considering the small number of species sampled. Moreover, all species showed a significant seasonal pattern for the reproductive phenophases, with high concentrations of species reproducing during a given season, suggesting a key role of climate in defining phenological patterns in the campo rupestre grasslands.

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OBJECTIVE:The present study aimed at estimating the prevalence of lifetime sexual abuse among women and at investigating its association with alcohol consumption.METHOD:Population-based survey conducted through a representative and stratified cluster sample of metropolitan São Paulo. GENACIS questionnaire was used. Sample unit was the home, and all residents aged 18 years and over were interviewed. The outcome was lifetime sexual abuse. The univariate statistical analysis used the Rao-Scott test. Logistic regression was used for the multivariate analysis.RESULTS:The final sample totalized 1,216 women aged 18 years and over; the response rate was 75.0%. Most women were married (56.6%) and had less than 12 years of formal education (59.0%); 46.2% were aged between 25 and 44 years, and 44.4% had a low income. Of the respondents, 7.5% reported having suffered lifetime sexual abuse. Multiple logistic regression model showed an association between lifetime sexual abuse and being a heavy drinker (OR = 4.97) and being a former drinker (OR = 2.04).CONCLUSIONS:There are few population studies in Brazil investigating sexual abuse and its relation to alcohol use. Although the prevalence of lifetime sexual abuse in the present study was smaller than that observed in other studies, it is a highly expressive percentage on account of its social and economic impact, as well as its potential effect on the health system.