微机化视频图形发生仪的研制

介绍了以单片机和ＣＲＴ显示器控制芯片ＣＲＴＣ为主的微机化视频图形发生仪的设计方法及原理．对用ＭＣ６８４５ＣＲＴＣ产生视频信号的方法及图象分辨率作了详细介绍，给出了将此视频图象发生仪作图象刺激仪的软件框图．     

On uniform approximation of Poisson variates by normal ones

In this paper the accuracy of the normal approximation to the Poisson is treated from the viewpoint of direct approximation of Poisson variables by normal ones. The conclusions that are derived on the accuracy of this approximation lead (among others) to very useful results on confidence limits for the mean of a linear combination of independent Poisson variables; these latter are employed in precise determination of the composition of a mixture of radioactive isotopes by means of a scintillation counter.     

À propos de l’article de François-Xavier de Vaujany, « Les figures de la gestion du changement sociotechnique »

The approach adopted by François Xavier de Vaujany draws from “structurationist” research in English-speaking social sciences, a current that shares with the sociology of technology a vision of the contextual and negotiated nature of the links between technical and organizational phenomena. Various trajectories in the way organizations use new information and communication technology can be compared; and the role, examined that specific mediators play in the appropriation process. This approach provides stimulating input in discussions about the impact of new technology on organizational change.     

Asymptotical improvement of maximum likelihood estimators on Kullback–Leibler loss

We discuss the general form of a first-order correction to the maximum likelihood estimator which is expressed in terms of the gradient of a function, which could for example be the logarithm of a prior density function. In terms of Kullback–Leibler divergence, the correction gives an asymptotic improvement over maximum likelihood under rather general conditions. The theory is illustrated for Bayes estimators with conjugate priors. The optimal choice of hyper-parameter to improve the maximum likelihood estimator is discussed. The results based on Kullback–Leibler risk are extended to a wide class of risk functions.     

Note on the Cramér-Rao inequality in the nonregular case: the family of uniform distributions

We consider the family of uniform distributions with range of unit length. The main result of this note asserts that the average variance of any unbiased estimator of the midpoint of the range is not less than (2(n+1))(n+2))^-1 and this lower bound is sharp. The proof is based upon a nonregular version of the Cramér-Rao inequality.     

Conditional inference for subject-specific and marginal agreement: Two families of agreement measures

A two-stage procedure is described for assessing subject-specific and marginal agreement for data from a test-retest reliability study of a binary classification procedure. Subject-specific agreement is parametrized through the log odds ratio, while marginal agreement is reflected by the log ratio of the off-diagonal Poisson means. A family of agreement measures in the interval [-1, 1] is presented for both types of agreement. The conditioning argument described facilitates exact inference. The proposed methodology is demonstrated by way of an example involving hypothetical data chosen for illustrative purposes, and data from a National Health Survey Study (Rogot and Goldberg 1966).     

Estimation of an exponential quantile under pitman's measure of closeness

We consider the problem of estimating a quantile of an exponential distribution with unknown location and scale parameters under Pitman's measure of closeness (PMC). The loss function is required to satisfy some mild conditions but is otherwise arbitrary. An optimal estimator is obtained in the class of location-scale-equivariant estimators, and its admissibility in the sense of PMC is investigated.     

Robust scale estimation in the error-components model using the empirical characteristic function

Robust estimators of the scale parameters in the error-components model are described. The new estimators are based on the empirical characteristic functions of appropriate sets of residuals and are affine equivariant, consistent and asymptotically normal. The robustness of the new estimators is investigated via influence-function calculations. The results of Monte Carlo experiments and an example based on real data illustrate the usefulness of the estimators.     

Resolving conflicting demands on evaluation: A test demonstration of videotex for farmers

Evaluating an innovation for federal, state, and local policymakers and program managers alike entails conflicting demands on the evaluation study. Policymakers at federal, state, and local levels are best assisted by impact evaluations, whereas state and local program managers are best assisted by process evaluations. In-house evaluators often have an advantage in conducting process evaluations; external evaluators generally have an advantage in conducting impact evaluations. A cost-effective approach may be to combine in-house process evaluation and external impact evaluation. This dual approach was found to reduce conflicting demands on the evaluation of an experimental videotex system for agricultural producers.     

Inference about permutation parameter in large samples

The estimation problem of a permutation parameter on the basis of a random sample of increasing size is considered. A necessary and sufficient condition for the existence of an estimator, asymptotically fully efficient for two different distributions families, is derived. We also study the application of this result to cyclic groups of order two and three.