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PubMed1999

[The influence of digoxin treatment on the statistical distribution of R-R intervals in atrial fibrillation].

Functional refraction of atrio-ventricular node and the phenomenon of concealed conduction are basic factors which determine the frequency of ventricular beats as well as the duration of R-R intervals in atrial fibrillation. R-R intervals may be ordered according to their size and presented graphically in the form of histograms. The morphology of histograms depends on the ability of A-V node. Digoxin influences the morphology of histograms of R-R intervals, which may have a diagnostic value and become a therapeutic indicator. The purpose of the study was to evaluate the correlation between the morphology of histograms and digoxin serum concentration, as well as the clinical treatment with digoxin. In the study a classification was used which divided R-R intervals into 4 types and several sub-types. The study covers 91 patients treated with digoxin upon whom 161 histograms were made. Two groups of patients were studied: A-patients in whom digoxin concentration was determined, B-patients in whom treatment with digoxin was evaluated on the basis of their clinical condition. The study confirmed a hypothesis that treatment with digoxin causes specific changes in the statistical distribution of R-R intervals even though no strict correlation was found between the direction of these changes and the digoxin serum concentration. The dependence, however, was observed between histograms of R-R intervals in atrial fibrillation and the clinical course of treatment with digoxin.

Adult↗
PubMed1985

Bone strength statistical distribution functions for broilers.

Shear and three-point bending tests were conducted on the femur and tibia bones from Hubbard broilers to establish the type of statistical distribution function that best fits bone strength data. In the past it was assumed that these types of data followed a normal distribution. The results of this investigation indicate that a log-normal function best describes the mechanical properties of the tibia and a normal function describes the properties of the femur. Overall the results of the distribution analysis indicate that the mechanical properties of bone tend to follow a log-normal distribution.

Animals↗
PubMed1980

[Use of the dynamics of central moments of statistical distributions to analyze muscle fiber differentiation].

The aim of the work is to demonstrate how it is possible to get informations of differentiation in muscle fibres by means of evaluating the dynamics of statistical distribution moments. Combinations of various directions of time changes of the standard deviations, asymmetry and excess give the possibility to construct tables in order to get immediate informations on changes occurring in different parts of the distribution (and, hence, on the course of the muscle fibres development) during the whole time of observation (age dynamics of NAD-H-D activity in fibres of musculus serratus ventralis in Wistar rats is studied as an example). Analysing dynamics, as well as real distribution features of the muscle fibres, we got doubtful on the presence of muscle fibre types that could be considered as independent (though possibly as over-lapping) populations. Various differentiation rates of the muscle fibres with different optic density do not mean development of a certain population, but rather reflect an increasing process of development of a part of a single muscle fibres complex, where separate members have various properties and in the course of development they smoothly change them in such a way that uninterruption and continuation of possible intermediate conditions is kept along the whole variational curve. This method could be applied to analyse any other objects after any quantitative sign.

Animals↗
PubMed2005

Statistical distribution of blood serotonin as a predictor of early autistic brain abnormalities.

BACKGROUND: A wide range of abnormalities has been reported in autistic brains, but these abnormalities may be the result of an earlier underlying developmental alteration that may no longer be evident by the time autism is diagnosed. The most consistent biological finding in autistic individuals has been their statistically elevated levels of 5-hydroxytryptamine (5-HT, serotonin) in blood platelets (platelet hyperserotonemia). The early developmental alteration of the autistic brain and the autistic platelet hyperserotonemia may be caused by the same biological factor expressed in the brain and outside the brain, respectively. Unlike the brain, blood platelets are short-lived and continue to be produced throughout the life span, suggesting that this factor may continue to operate outside the brain years after the brain is formed. The statistical distributions of the platelet 5-HT levels in normal and autistic groups have characteristic features and may contain information about the nature of this yet unidentified factor. RESULTS: The identity of this factor was studied by using a novel, quantitative approach that was applied to published distributions of the platelet 5-HT levels in normal and autistic groups. It was shown that the published data are consistent with the hypothesis that a factor that interferes with brain development in autism may also regulate the release of 5-HT from gut enterochromaffin cells. Numerical analysis revealed that this factor may be non-functional in autistic individuals. CONCLUSION: At least some biological factors, the abnormal function of which leads to the development of the autistic brain, may regulate the release of 5-HT from the gut years after birth. If the present model is correct, it will allow future efforts to be focused on a limited number of gene candidates, some of which have not been suspected to be involved in autism (such as the 5-HT4 receptor gene) based on currently available clinical and experimental studies.

Autistic Disorder↗
PubMed2004

Statistical distributions describing microbial quality of surfaces and foods in food service operations.

Data on the microbial quality of food service kitchen surfaces and ready-to-eat foods were collected over a period of 10 years in Rutgers University dining halls. Surface bacterial counts, total aerobic plate counts, and total and fecal coliform counts were determined using standard methods. Analysis was performed on foods tested more than 50 times (primarily lunch meats and deli salads) and on surfaces tested more than 500 times (36 different surfaces types, including pastry brushes, cutting boards, and countertops). Histograms and statistical distributions were determined using Microsoft Excel and Palisades Bestfit, respectively. All data could be described by lognormal distributions, once data above and below the lower and upper limits of detection were considered separately. Histograms for surfaces counts contained one peak near 1 CFU/4 cm2. Surfaces with higher levels of contamination tended to be nonmetal, with the exception of buffalo chopper bowls, which commonly had high counts. Mean counts for foods ranged from 2 to 4 log CFU/g, with shrimp salad, roast beef, and bologna having higher means. Coleslaw, macaroni salad, and potato salad (all commercially processed products, not prepared in the dining halls) had lowest overall means. Coliforms were most commonly found in sealeg salad (present in 61% of samples) and least commonly found in coleslaw (present in only 7% of samples). Coliform counts (when present) were highest on average in shrimp salad and lowest in coleslaw. Average coliform counts for most products were typically between 1 and 2 log most probable number per gram. Fecal coliforms were not typically found in any deli salads or lunch meats.

Bacteria↗
PubMed1992

Local tissue oxygenation by statistically distributed sources.

The effect of red blood cell separation on tissue oxygenation was analyzed using a previously developed model which accounts for the particulate nature of blood at the capillary level. Results show that an empirically based RBC pattern yields the same levels of oxygenation at 20% hematocrit as an even spacing pattern. Introduction of an empirically based RBC spacing pattern during hemodilution, where capillary hematocrit is reduced by half with concomitant doubling of velocity, results in a reduction of average tissue pO2 by 23% and volume of oxygenated tissue by 28%, whereas axial delivery of oxygen along the length of the capillary was unchanged. Tissue oxygenation levels are optimized with even RBC spacing pattern but not with an empirical pattern because the tissue does not effectively use the oxygen delivered by unevenly spaced RBCs despite an equivalent time-averaged flux. Model predictions for tissue oxygenation for statistically distributed spacing under normal and hemodilution conditions show trends consistent with previously obtained results using even spacing, namely, increased axial distance and volume oxygenated, with decreased average tissue pO2. During hemodilution, the volume of tissue oxygenated above 2 mm Hg decreased to 84%, while the volume above 1 mm Hg increased to 131% relative to control. This finding suggests a redistribution of oxygen within tissue during hemodilution, causing a greater amount of tissue to be exposed, but at a lower pO2.

Animals↗
PubMed1998

The statistical distribution of wrist movements during sleep.

The purpose of this work was to describe the basic statistical properties of the process of production of movements measured with a wrist actimeter, along a complete sleep period in normal human subjects. Two distinct types of random magnitudes were considered to analyze the data, the times between successive groups of movements and the number of movements at each fixed time (1 min) measurement epoch. Suitable probabilistic models for the two variates were chosen, fitting theoretical distribution functions to the observed data. It is concluded that interval data fit a one-parameter exponential distribution, while the number of movements fit a two-parameter negative binomial distribution. The estimated values of these parameters, besides being necessary to perform further statistical analysis, are a measure of the intensity and frequency of the movements. Finally the relationship between polysomnography measures and the elicited parameters was studied.

Adult↗
PubMed2003

Coding DNA sequences: statistical distributions.

The base distributions in coding DNA sequences (CDS) are investigated. We explore the scaling properties of the 4-dimensional directed random walk and compare them with that for the DNA sequences. Inference from these observation are, however, contradicted by alternate analysis using factorial moments. To resolve this conflict we look directly at the nucleotide base distributions. In all the cases the base distributions change from gaussian to non-gaussian as the scale size is increased. The CDS, therefore, have nucleotide distributions different from the random.

Animals↗
PubMed1982

[Analysis of the statistical distribution of aminolevulinic acid dehydratase in a population not exposed to occupational chemical factors].

The subject of the paper has been to check the aminolevulinic dehydratase (ALAD) activity in those with no occupational exposure to inhibitors of this enzyme. Altogether 293 persons have been examined, 132 women and 161 men, aged 20-69. The resultant ALAD activity distribution showed no differences between women and men, though statistically significant differences have been found between the mean values. The distribution did not deviate from normal in both groups. The analysis of ALAD activity distribution in particular age groups, whether female or male, showed statistically significant differences. No clear dependence between ALAD activity and haemoglobin concentration in blood has been found. On the other hand, clear differences in ALAD activity between groups of high and low haemoglobin concentrations have been found. In addition to the mentioned examinations, 32 persons (12 women and 20 men) presently exposed to lead had their lead concentration determined in blood. No correlations have been found between lead concentrations in blood and ALAD activity.

Adult↗