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321.
采用电刺激兔下丘脑室旁核后观察血流动力学的变化,初步探讨中枢神经系统对心肌力调控的机理。发现室旁核被刺激兴奋后,不但有升高动脉血压的作用,更重要的是对心脏有正性肌力的作用并同时增加心肌氧耗量,其机制可能与室旁核内NMDA受体的激活有关。 相似文献
322.
Clazien J. De Vos Mirjam Nielen Emelinda Lopez Armin R.W. Elbers Aldo Dekker 《Risk analysis》2010,30(4):605-618
Emergency vaccination is an effective control strategy for foot‐and‐mouth disease (FMD) epidemics in densely populated livestock areas, but results in a six‐month waiting period before exports can be resumed, incurring severe economic consequences for pig exporting countries. In the European Union, a one‐month waiting period has been discussed based on negative test results in a final screening. The objective of this study was to analyze the risk of exporting FMD‐infected pig carcasses from a vaccinated area: (1) directly after final screening and (2) after a six‐month waiting period. A risk model has been developed to estimate the probability that a processed carcass was derived from an FMD‐infected pig (Pcarc). Key variables were herd prevalence (PH), within‐herd prevalence (PA), and the probability of detection at slaughter (PSL). PH and PA were estimated using Bayesian inference under the assumption that, despite all negative test results, ≥1 infected pigs were present. Model calculations indicated that Pcarc was on average 2.0 × 10?5 directly after final screening, and 1.7 × 10?5 after a six‐month waiting period. Therefore, the additional waiting time did not substantially reduce Pcarc. The estimated values were worst‐case scenarios because only viraemic pigs pose a risk for disease transmission, while seropositive pigs do not. The risk of exporting FMD via pig carcasses from a vaccinated area can further be reduced by heat treatment of pork and/or by excluding high‐risk pork products from export. 相似文献
323.
R.R. Hocking 《统计学通讯:理论与方法》2013,42(12):4591-4617
Closed form expressions are developed for the estimators of functions of the variance components in balanced, mixed, linear models. These estimators are averages of sample covariances (variances) which offer diagnostic information on the data and the model. The cause of negative estimates may be revealed. Examples illustrate the basic concepts. 相似文献
324.
L.D. Broemeling 《统计学通讯:理论与方法》2013,42(3):297-305
Earlier investigations used a one-sided inequality to consltuct confidence regions for the variance ratios or balanced randoiu models. In this study, confidence regions are based on a two-sided generalisation of this inequality and the results are illustrated by estimating the parameters of some elementary random models. 相似文献
325.
《随机性模型》2013,29(2):157-190
In this paper, we establish an explicit form of matrix decompositions for the queue length distributions of the MAP/G/1 queues under multiple and single vacations with N-policy. We show that the vector generating function Y (z) of the queue length at an arbitrary time and X (z) at departures are decomposed into Y (z) = p idle (z)ζ Y (z) and X (z) = p idle (z)ζ X (z) where p idle (z) is the vector generating function of the queue length at an arbitrary epoch at which the server is not in service, and ζ Y (z) and ζ X (z) are unidentified matrix generating functions. 相似文献
326.
《随机性模型》2013,29(2-3):615-630
Abstract Recently, risk processes have been analyzed as fluid queues. That approach is adapted here to the analysis of the token bucket model for Markovian traffic patterns. This paper presents the Laplace transform of the time until a given traffic pattern is not compliant anymore with a particular token bucket model. 相似文献
327.
S. John 《统计学通讯:理论与方法》2013,42(8):879-885
This note introduces a family of skew and symmetric distributions containing the normal family and indexed by three parameters with clear meanings. Another respect in which this family compares favourably with families like the Pearson family, the Bessel-Gram-Charlier family and the Johnson family is ease of maximum likelihood fitting. Fitting by the method of moments is also considered. Asymptotic distributions of maximum likelihood and moment estimators are worked out. A test of symmetry and normality is suggested. 相似文献
328.
Partial specification of a prior distribution can be appealing to an analyst, but there is no conventional way to update a partial prior. In this paper, we show how a framework for Bayesian updating with data can be based on the Dirichlet(a) process. Within this framework, partial information predictors generalize standard minimax predictors and have interesting multiple-point shrinkage properties. Approximations to partial-information estimators for squared error loss are defined straightforwardly, and an estimate of the mean shrinks the sample mean. The proposed updating of the partial prior is a consequence of four natural requirements when the Dirichlet parameter a is continuous. Namely, the updated partial posterior should be calculable from knowledge of only the data and partial prior, it should be faithful to the full posterior distribution, it should assign positive probability to every observed event {X,}, and it should not assign probability to unobserved events not included in the partial prior specification. 相似文献
329.
广义kdv方程的局部解与整体解 总被引:2,自引:0,他引:2
郑丽霞 《内蒙古工业大学学报》1998,17(4):5-12
本文研究了广义Kdv方程(GP)的初值问题,利用基本解及压缩映象原理,证明了非齐次项f(u,ux)充分光滑的条件下,局部解的存在唯一性,并对特殊的f(u,ux)得到了整体解的存在唯一性。 相似文献
330.
S. R. Paul 《The American statistician》2013,67(2):136-139
Binary-response data arise in teratology and mutagenicity studies in which each treatment is applied to a group of litters. In a large experiment, a contingency table can be constructed to test the treatment X litter size interaction (see Kastenbaum and Lamphiear 1959). In situations in which there is a clumped category, as in the Kastenbaum and Lamphiear mice-depletion data, a clumped binomial model (Koch et al. 1976) or a clumped beta-binomial model (Paul 1979) can be used to analyze these data. When a clumped binomial model is appropriate, the maximum likelihood estimates of the parameters of the model under the hypothesis of no treatment X litter size interaction, as well as under the hypothesis of the said interaction, can be estimated via the EM algorithm for computing maximum likelihood estimates from incomplete data (Dempster et al. 1977). In this article the EM algorithm is described and used to test treatment X litter size interaction for the Kastenbaum and Lamphiear data and for a set of data given in Luning et al. (1966). 相似文献