1,159 research outputs found

    CSM digital autopilot testing in support of ASTP experiments control requirements

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    Results are presented of CSM digital autopilot (DAP) testing. The testing was performed to demonstrate and evaluate control modes which are currently planned or could be considered for use in support of experiments on the ASTP mission. The testing was performed on the Lockheed Guidance, Navigation, and Control System Functional Simulator (GNCFS). This simulator, which was designed to test the Apollo and Skylab DAP control system, has been used extensively and is a proven tool for CSM DAP analysis

    Analysis of resonant responses of split ring resonators using conformal mapping techniques

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    We report a novel method for modeling the resonant frequency response of infra-red light, in the range of 2 to 10 microns, reflected from metallic spilt ring resonators (SRRs) fabricated on a silicon substrate. The calculated positions of the TM and TE peaks are determined from the plasma frequency associated with the filling fraction of the metal array and the equivalent LC circuit defined by the SRR elements. The capacitance of the equivalent circuit is calculated using conformal mapping techniques to determine the co-planar capacitance associated with both the individual and the neighbouring elements. The inductance of the equivalent circuit is based on the self-inductance of the individual elements and the mutual inductance of the neighboring elements. The results obtained from the method are in good agreement with experimental results and simulation results obtained from a commercial FDTD simulation software package. The method allows the frequency response of a SRR to be readily calculated without complex computational methods and enables new designs to be optimised for a particular frequency response by tuning the LC circuit

    Equinococose cĂ­stica no sul do Brasil

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    Cystic echinococcosis (CE) is very common in the southern part of Rio Grande do Sul State where sheep and cattle raising is the most important economical activity. Prevalence in intermediate hosts is well known due to reports in slaughterhouses while human reports are of discussed value. This is due to underreporting of cases and few epidemiological studies make it difficult to assess the situation of echinococcosis in the population. Whereas cattle infection rate is more or less stable around 12% of the slaughter animals, in sheep there has been an increasing number in the last five years. Some efforts have been done to control the zoonosis but no effective results were obtained so far. Probably educational efforts to change human practices (feeding dogs with raw viscera), periodic treatment of dogs with praziquantel and joined actions with slaughterhouses could bring more attention to improve some control measures.A equinococose cística (CE) é muito comum na região sul do estado do Rio Grande do Sul, onde a criação de bovinos e ovinos representa a maior atividade econômica. A prevalência nos hospedeiros intermediários é bem conhecida devido aos registros em frigoríficos enquanto que os casos humanos apresentam dados discutíveis e de difícil interpretação. Isto é devido a subnotificação e os poucos estudos epidemiológicos tornam difícil a avaliação da equinococose na população. Enquanto que a prevalência em bovinos estabilizou ao redor de 12% de animais abatidos na última década, em ovelhas está ocorrendo um aumento nos últimos cinco anos. Algumas tentativas estão sendo feitas para controlar esta zoonose mas não tem sido obtidos resultados práticos até agora. Provavelmente ações educativas que alterem comportamentos humanos (alimentação de cães com vísceras cruas), tratamento periódico dos cães com praziquantel e ações junto a frigoríficos poderiam resultar em incremento nas medidas de controle devido às perdas econômicas mensuráveis

    Modelling seasonal patterns in longitudinal profiles with correlated circular random walks

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    Seasonal patterns, as they occur in time series of infectious disease surveillance counts, are frequently modelled using a superposition of sine and cosine functions. However, in some cases this might be too simple. We propose the use of circular second order random walks instead and extend this approach to multivariate time series of counts. A correlated Gaussian Markov random field approach combines a uniform correlation matrix with a circular random walk to allow the seasonal pattern to be similar across regions, say, but not identical. Thus, spatially-varying disease onsets may be accounted for. The methodology is applied to weekly number of deaths from in uenza and pneumonia in nine major regions of the USA

    A Bayesian spatial assimilation scheme for snow coverage observations in a gridded snow model

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    International audienceA method for assimilating remotely sensed snow covered area (SCA) into the snow subroutine of a grid distributed precipitation-runoff model (PRM) is presented. The PRM is assumed to simulate the snow state in each grid cell by a snow depletion curve (SDC), which relates that cell's SCA to its snow cover mass balance. The assimilation is based on Bayes' theorem, which requires a joint prior distribution of the SDC variables in all the grid cells. In this paper we propose a spatial model for this prior distribution, and include similarities and dependencies among the grid cells. Used to represent the PRM simulated snow cover state, our joint prior model regards two elevation gradients and a degree-day factor as global variables, rather than describing their effect separately for each cell. This transformation results in smooth normalised surfaces for the two related mass balance variables, supporting a strong inter-cell dependency in their joint prior model. The global features and spatial interdependency in the prior model cause each SCA observation to provide information for many grid cells. The spatial approach similarly facilitates the utilisation of observed discharge. Assimilation of SCA data using the proposed spatial model is evaluated in a 2400 km2 mountainous region in central Norway (61° N, 9° E), based on two Landsat 7 ETM+ images generalized to 1 km2 resolution. An image acquired on 11 May, a week before the peak flood, removes 78% of the variance in the remaining snow storage. Even an image from 4 May, less than a week after the melt onset, reduces this variance by 53%. These results are largely improved compared to a cell-by-cell independent assimilation routine previously reported. Including observed discharge in the updating information improves the 4 May results, but has weak effect on 11 May. Estimated elevation gradients are shown to be sensitive to informational deficits occurring at high altitude, where snowmelt has not started and the snow coverage is close to unity. Caution is therefore required when using early images

    Correlated GMRF priors for multivariate age-period-cohort models

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    Multivariate age-period-cohort models have recently been proposed for the analysis of heterogeneous time trends. For a fully Bayesian analysis, Gaussian Markov random field (GMRF) priors are typically used. However, standard GMRF priors do not account for a potential dependence between outcomes. We present an extended approach based on correlated smoothing priors and corre-lated overdispersion parameters. Algorithmic routines are based on either Markov chain Monte Carlo or integrated nested Laplace approximations. Results are discussed for data on female mortality in Denmark and Norway and compared by means of DIC, proper scoring rules and the marginal likelihood

    Removal of AMPA receptors (AMPARs) from synapses is preceded by transient endocytosis of extrasynaptic AMPARs

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    AMPA receptors (AMPARs) are dynamically regulated at synapses, but the time course and location of their exocytosis and endocytosis are not known. Therefore, we have used ecliptic pHluorin-tagged glutamate receptor 2 to visualize changes in AMPAR surface expression in real time. We show that synaptic and extrasynaptic AMPARs respond very differently to NMDA receptor activation; there is a rapid internalization of extrasynaptic AMPARs that precedes the delayed removal of synaptic AMPARs

    Prohibiting Good Faith Reports Under the Uniform Mediation Act: Keeping the Adjudication Camel out of the Mediation Tent

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    This symposium article examines a narrow slice of the Uniform Mediation Act - the prohibition on mediator communication to judges about a party\u27s good faith participation or problem behavior in mediation
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