Sequential Correlation Research Articles

On Nonparametric Sequential Tests for Independence

A nonparametric sequential rank correlation test for independence consisting of a generalized sequential probability ratio test is investigated through the Monte Carlo method. The test is found to be satisfactory in terms of the power function. Comparison of the expected sample size of the test and three other tests including the fixed sample size test suggests that the sequential rank test is also efficient.

On Nonparametric Sequential Tests for Independence

A nonparametric sequential rank correlation test for independence consisting of a generalized sequential probability ratio test is investigated through the Monte Carlo method. The test is found to be satisfactory in terms of the power function. Comparison of the expected sample size of the test and three other tests including the fixed sample size test suggests that the sequential rank test is also efficient.

Speech Data Rate Reduction Part I: Applicability of Modern Estimation Theory

Efficient coding of continuous speech signals for digital representation has attracted much interest in recent years. The underlying aim of efficient coding methods is to reduce the channel capacity required to represent a signal to meet a specific reconstruction fidelity criterion. To achieve this objective, modern speech data compression techniques rely on two very similar procedures. One procedure uses predictive deconvolution which subtracts from the current signal value that portion which can be predicted from its past and thus removes redundancy in the speech by removing sequential correlation. The signal thus requires fewer bits for equivalent quantization error. The second procedure involves identification of a complete mathematical model of the speech producing mechanism. This involves determination of the characteristics of the source that drives this transfer function. Data reduction is again achieved since the rate of change of the parameters of the speech model is much smaller than the rate of change of the speech waveform. This paper develops these data reduction procedures in terms of modern estimation theory, specifically a Kalman filter model, and illustrates the utility of this model as an analysis tool by means of an example based on a uniform tube which provides a qualitative assessment of the potential of the technique for application to real speech signals.

The olfactory bulb lesion in the hibernating squirrel (Citellus lateralis) infected with coxsackievirus B-3. II. Immunological study.

The immunological response was studied in the adult hibernating squirrel (Citellus lateralis) infected with coxsackievirus B-3. The complement activity was considerably reduced between the 4th and 9th day of infection, but was restored to the normal level by the 11th day. The neutralizing antibody was first detected in the blood on the fourth day, reached an average ND50 of 10−2.62 on the seventh day after inoculation, and remained at this level.Gamma globulin was demonstrated in the infected olfactory bulb by the direct fluorescent antibody method on the seventh day after inoculation. The specific fluorescence appeared as a surface staining of the infected granule cells, cellule nervose piccole, and within numerous inflammatory cells. On staining with methyl green – pyronin these cells resembled the antibody-producing cells in the spleen.A sequential correlation existed between the development and appearance of the gamma-globulin-producing cells in the spleen and the olfactory bulb which indicated that the lymphoid cells infiltrated into and contributed to the tissue destruction in the olfactory bulb of the infected squirrel.

Unsupervised Learning Minimum Risk Pattern Classification for Dependent Hypotheses and Dependent Measurements

A recursive Bayes optimal solution is found for the problem of sequential multicategory pattern recognition when unsupervised learning is required. An unknown parameter model is developed which, for the pattern classification problem, allows for 1) both constant and time-varying unknown parameters, 2) partially unknown probability laws of the hypotheses and time-varying parameter sequences, 3) dependence of the observations on past as well as present hypotheses and parameters, and most significantly, 4) sequential dependencies in the observations arising from either (or both) dependency in the pattern or information source (context dependence) or in the observation medium (sequential measurement correlation), these dependencies being up to any finite Markov orders. For finite parameter spaces, the solution which is Bayes optimal (minimum risk) at each step is found and shown to be realizable in recursive form with fixed memory requirements. The asymptotic properties of the optimal solution are studied and conditions established for the solution (in addition to making best use of available data at each step) to converge in performance to operation with knowledge of the (unobservable) constant unknown parameters.

Calcium flux in the mammalian ventricular myocardium.

The exchange of Ca(45) was studied in dog myocardium by means of a newly developed perfusion technique whereby an excised papillary muscle was perfused through its own artery. This makes possible the sequential and simultaneous correlation of ionic flux with ventricular myocardial function with each muscle serving as its own control. Calcium exchange has the following characteristics: (a) The major component of calcium flux is independent of the frequency of contraction. It demonstrates a rapidly equilibrating phase (half-time, 4 to 6 minutes) and a more slowly equilibrating phase with a progressively decreasing rate constant. The flux characteristics of the more rapidly equilibrating compartment are determined by a factor or factors, in addition to simple diffusion, which increase the time required for this compartment to achieve a steady-state with respect to the vascular compartment. (b) A lesser component of exchange is stimulus-rate dependent and is characterized by an alteration in the rate of calcium turnover such that the altered influx: efflux ratio requires 20 to 25 minutes to achieve equilibrium. After this time, despite the higher stimulus rate, there is no evidence of change in total tissue calcium. (c) The initial rate of the transient response is approximately proportional to the change in stimulus rate.

Information content of the mean

The amount of information given by a statistical estimate is defined as the reciprocal of the variance of the estimate. In this study, a random series is adopted as the standard of information content. The relative information content of the mean for various types of hydrologic series is defined as the ratio of the variance of the mean for a random series to the variance of the mean for given types of series. Beyond the well-known fact that the sequential correlation in hydrologic series reduces the effective length of the series, the sequential correlation tends to impair the effectiveness of cross-correlations between series. There are limits, therefore, upon increasing the information content of a mean by utilizing the information contained in a related series. Moreover, cross-correlation tends to decrease the effective length of series for computing regional means.

Queuing Theory and Water Storage

Method for determining amount of holdover storage for regulating stream flow; derivation of expression for case where discharge varies linearly with reservoir contents; use of queuing analogy to generalize solution by probability routing; effect of sequential correlation.