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A computer program for multivariate ratio analysis (MISCAT).

Analysts must deal frequently with missing data in multivariate analysis. In such cases, estimating the covariance maxtrix V of the dependent variables usually involves initial estimation and iterative adjustment of imputed missing data values, and/or smoothing of an estimate V which is not necessarily positive semi-definite. This paper presents an alternative procedure for computing estimates of relevant multivariate parameters in situations where missing data occur at random and with small probability. MISCAT is a computer program which computes multivariate ratio estimates of the means and a corresponding positive semi-definite estimate of the covariance matrix. It is an extension of GENCAT, which is a program for the generalizaed least squares analysis of categorical data. Thus, one advantage of dealing with missing data in this manner is that variation among the ratio estimates may be conveniently analyzed within MISCAT using asymptotic regression methodology, provided that sample sizes are sufficiently large. An example is given to illustrate such analysis for longitudinal data from a multicenter clinical trial.

Computers

A computer program for stepwise logistic regression using maximum likelihood estimation.

A computer program has been written which performs a stepwise selection of variables for logistic regression using maximum likelihood estimation. The selection procedure is based on likelihood ratio tests for the coefficients. These tests are used in a forward selection and a backward elimination at each step. The use of the program is illustrated by several examples.

Computers

Development of a computer program to analyze the parameters of platelet-vessel wall interaction.

The use of the Baumgartner perfusion system allows the morphometric quantification of platelets interacting with vessel wall, however it presents the basic difficulties of morphometrical measurements. In order to facilitate the procedure of evaluation we developed a semiautomated method to avoid the complexity of the classical evaluation. Our system consists on an optical picture analysis system connected with a specially developed computer program which allows fast quantification. Simultaneously to the outlining of interacting platelets the computer program recognizes, corrects, selects and stores the information, in order to perform the final calculations as previously established. This system has been demonstrated to be as effective as the classical morphometric evaluation in the measure of platelets interacting with subendothelium. Potential sources of error such as subjectivity of the observers in selecting the class of interacting platelets are avoided. The use of this combined method opens the possibility to adapt the Baumgartner perfusion system to clinical routine and to the screening of drugs that modify platelet adherence.

Animals

The AAHA Computer Program. American Animal Hospital Association.

The American Animal Hospital Association Computer Program should benefit all small animal practitioners. Through the availability of well-researched and well-developed certified software, veterinarians will have increased confidence in their purchase decisions. With the expansion of computer applications to improve practice management efficiency, veterinary computer systems will further justify their initial expense. The development of the Association's veterinary computer network will provide a variety of important services to the profession.

Animals

Reduction of the limitations for the calculations of shielding effects with Van de Geijn's computer program.

The possibilities for reducing in Van de Geijn's computer program the original limitations for the size and the position within the field of shielding blocks are explored. New methods are presented which are based on experimental measurements as well as more theoretical approaches, without need for any change in the program itself. Two typical clinical examples are presented and the precision obtained critically investigated.

Cobalt Radioisotopes

A simple computer program for optimization of source loading in cervical intracavitary applicators.

A computer program has been developed to aid in the brachytherapy of cancer of the cervix. Using a least-squares minimization algorithm, the program will optimize the source loading in intracavitary applicators so as to reproduce, as nearly as physical considerations allow, the dose distribution requested by the user. Applicator geometry and the relative positions of anatomical points of interest must be supplied to the program, as well as an inventory of available source strengths. Output from the computer includes the optimized source loading, time of application, and the resulting relative doses to the various user-selected points of interest.

Computers

A computer program for multiple decrement life table analyses.

Life table analysis has traditionally been the tool of choice in analyzing distribution of "survival" times when a parametric form for the survival curve could not be reasonably assumed. Chiang, in two papers [1,2] formalized the theory of life table analyses in a Markov chain framework and derived maximum likelihood estimates of the relevant parameters for the analyses. He also discussed how the techniques could be generalized to consider competing risks and follow-up studies. Although various computer programs exist for doing different types of life table analysis [3] to date, there has not been a generally available, well documented computer program to carry out multiple decrement analyses, either by Chiang's or any other method. This paper describes such a program developed by Research Triangle Institute. A user's manual is available at printing costs which supplements the contents of this paper with a discussion of the formula used in the program listing.

Computers

A computer program for analyzing bivariate flow karyotypes.

This article describes a computer program for analyzing bivariate flow karyotypes of human chromosomes stained with Hoechst 33258 (HO) and chromomycin A3 (CA). The karyotype first is divided into regions that contain chromosome peaks. The chromosomes that are associated with those areas are identified. The distributions in these areas then are fitted with mathematical functions of increasing complexity. The process starts by fitting a specified number of univariate Gauss functions to projections of the HO and CA distributions of each area. The final fit can include multiple bivariate Gauss functions, including a background function for debris subtraction. The results of one stage in the fitting process serve as seed values for the next, more complex step. Since the program autonomously estimates the starting values for the iterative fitting procedures, the fit results are insensitive to operator bias and the program will consistently converge to the same solutions. The resulting table of parameter values can be used to compare flow karyotypes to a reference data set.

Chromomycin A3

Computer programs for the analysis of protein fluorescence quenching data.

Educational computer programs for analysis of fluorescence quenching studies of proteins have been developed. The program is written according to the classical Stern-Volmer equation and some modified Stern-Volmer equations. The static and dynamic quenching constants as well as the accessibility of the quencher molecules to the fluorescence groups are calculated. The experimental data are plotted on a high resolution graph. The calculated data or the graphs can be printed out to obtain a hard copy for filing.

Kinetics

An integrated set of computer programs for processing electron micrographs of biological structures.

A set of computer programs is described which has been developed for processing electron micrographs of biological structures. The programs provide facilities for efficient image storage, enhancement and display. Extensive programs are available for analysis of images of structures with translational, rotational and helical symmetry, and for performing 3-dimensional reconstruction. The considerations which went into the design of the system are listed. A description is provided of the means of control of the main program, which performs the majority of the image processing operations, and an example is given to illustrate its use. These programs are compared with other program systems also developed for micrograph image processing.

Computers

A computer program for automatic plotting of isopotential contours in CNS.

A computer program was developed in a Basic (Applesoft) version for generating up to five isopotential curves from field potentials recorded in nervous structures. Voltages are fed according to a cartesian coordinate system, and an area is delineated each four points in which a certain number of intermediate voltage points are calculated, according to the required resolution. The calculated values are compared to those prefixed for each curve and, if similar, their coordinates are stored in corresponding bidimensional matrixes. A special subroutine was designed for constructing an isometric tridimensional perspective of the isopotential curve ensemble. The reliability of this program was tested in the localization of sensory representation areas on the neocortex of the South American armadillo (Chaetophractus vellerosus) studied by evoked potential mapping following visual, auditory and somatosensory stimuli. The isopotential curves traced permitted a quantitative evaluation of the cortical activated areas, and from their topographical distribution, relative unresponsive zones could be inferred where only inconspicuous responses were obtained. It is concluded that the present program provides a reliable and fast method for studying the evoked potential's spatial distribution over the entire neocortex. In addition, it can be extended to the study of curves or contours which connect equivalent values pertaining to biophysical magnitudes other than voltage data.

Animals

A computer program for molecular weight determination of DNA fragments (HOWBIG).

The computer program HOWBIG has been developed based on the reciprocal correlation of size to migration distance of DNA in high voltage gradient gel systems (Southern, 1979). For calculation the program automatically chooses three marker bands migrating closest to the calculated band, reducing the error down to approximately 0.5% or less (reciprocal method, local form of calculation). The big advantages of the completely menu-driven program are high accuracy, error detectability, speed and ease of data handling. Management of marker-DNA molecular weights, data and analyses as files included in the menu driven program speeds up every-day lab work.

DNA

A PC based computer program to aid the preparation of solvent systems for the HPLC.

An interactive computer program, SOLCOMP, is developed which calculates the volumes of the components that are to be added to obtain either a fresh solvent mixture or a new solvent system from the old one of required composition. The code is implemented in MicroSoft FORTRAN and GWBASIC which runs on any IBM compatible PC under MSDOS environment.

Algorithms

[A computer program for toxico-chemical analysis using gas chromatography].

A high probability of identification of substances containing nitrogen or phosphorus in their molecules is obtained by the original gas chromatographic (GC) system. It enables the reliability of positive identification in 98.43% of cases compared with the modern GC where for the chromatographic library spectrum of 200 substances the probability of identification of unknown substances is only 28.13%. GC system is based on the parallel configuration of the two capillary columns of different polarities connected to the one-column injector and the one nitrogen-phosphorus detector as well as the original computer program developed on the qualitative-logistic approach to interpretation of chromatographic parameters using only one reference substance. The computer program can perform positive logistic identification also in the case when the unknown substance is in the closest chromatographic vicinity, with quite different reference substances on both capillary columns.

Chromatography, Gas

A computer program to record technical data in leukapheresis and plateletpheresis procedures.

A computer program for the recording of data and calculation of results from leukapheresis and plateletpheresis procedures is described. It provides a printout of cell yields and other results for each procedure, as well as an updated list of donors and phereses. The data are kept on tape, accessible for periodic statistical analysis. While primarily set up for use with Haemonetics (intermittent-flow centrifugation) equipment, the program is adaptable for other systems.

Blood Transfusion

Mixed oligo designer (MOD), a computer program to aid planning of automated, mixed oligodeoxyribonucleotide synthesis for mutagenesis experiments.

A computer program, MOD (mixed oligo designer), which aids in planning site-directed mutagenesis experiments using highly substituted oligodeoxyribonucleotides (oligos), is described. The program calculates the relationship between the degree of oligo substitution and the mutation frequency, in order to achieve an optimal level of mutagenesis. The program can be used on a wide variety of computers and runs under a number of different operating systems.

Algorithms

[A computer program for recognition of normal and pathologic blood and bone marrow cells].

A computer program to identify normal and pathological blood and marrow cells is presented. It requires an analysis of cellular morphology according to ten simple criteria. These criteria are treated by the Bayesian method; then the program offers, in decreasing order, the cells which are best classified. The responses are analyzed and discussed. This program seems to be well suitable to a computer-assisted teaching (CAT) of cytology. It supplements effectively the traditional methods.

Bayes Theorem

[A computer program for the interpretation of the acid-base status and respiratory gases].

A computer program for analysing the parameters of the acid-base status and respiratory gases has been designed. The program separates cases which are included into classical picture of certain respiratory, metabolic and mixed disorders. Out of a test series of 200 findings, 93% findings have been accurately interpreted. The program is written in BASIC, translated into machine code and occupies about 25 Kbyte computer memory. The main parts of the program use commands which do not favorize any version of BASIC increasing the program portability to other systems. The classification of respiratory gases and acid-base status was based on the already known facts.

Acid-Base Equilibrium