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PubMed2000

[Study on statistical method of distribution for erythrocyte morphological features by computerized image processing].

This study sought to develop a new statistic method for the semiautomatic analysis and classification of erythrocyte morphology based on the morphological features and shape analysis of erythrocytes by computer image processing. Shape factor as the description of the erythrocyte morphological features was used for the shape classification of erythrocytes. And the models and algorithms of erythrocytes image segmentation, cell body shape recognition and measure can be implemented through the VC++. The present method can efficiently and semi-automatically provide the statistical analysis of erythrocyte morphology, and can give the distribution of erythrocyte morphological features. The result showed that there was a significant difference between the distribution curves of the normal erythrocyte morphology (one apex) and hemolytic anemia's (two apices). By this way, it can be obtained the proportion data of different cell bodies' shapes. This method could provide some information for the study and diagnosis of the diseases (e.g. hemolytic anemia, pre-leukemia) related to erythrocyte morphology.

Algorithms↗
PubMed1994

Molecular distributions in interphases: statistical mechanical theory combined with molecular dynamics simulation of a model lipid bilayer.

A mean-field statistical mechanical theory has been developed to describe molecular distributions in interphases. The excluded volume interaction has been modeled in terms of a reversible work that is required to create a cavity of the solute size against a pressure tensor exerted by the surrounding interphase molecules. The free energy change associated with this compression process includes the configuration entropy as well as the change in conformational energy of the surrounding chain molecules. The lateral pressure profile in a model lipid bilayer (30.5 A2/chain molecule) has been calculated as a function of depth in the bilayer interior by molecular dynamics simulation. The lateral pressure has a plateau value of 309 +/- 48 bar in the highly ordered region and decreases abruptly in the center of the bilayer. Model calculations have shown that for solute molecules with ellipsoidal symmetry, the orientational order increases with the ratio of the long to short molecular axes at a given solute volume and increases with solute volume at a given axial ratio, in accordance with recent experimental data. Increased lateral pressure (p perpendicular) results in higher local order and exclusion of solute from the interphase, in parallel with the effect of surface density on the partitioning and local order. The logarithm of the interphase/water partition coefficient for spherical solutes decreases linearly with solute volume. This is also an excellent approximation for elongated solutes because of the relatively weak dependence of solute partitioning on molecular shape. The slope is equal to (2p perpendicular - p parallel)/3KBT, where p parallel is the normal pressure component, and different from that predicted by the mean-field lattice theory. Finally, the lattice theory has been extended herein to incorporate an additional constraint on chain packing in the interphase and to account for the effect of solute size on partitioning.

Biomechanical Phenomena↗
PubMed2006

Adaptive algorithms for two-channel polarization sensing under various polarization statistics with nonuniform distributions.

The polarization of light carries much useful information about the environment. Biological studies have shown that some animal species use polarization information for navigation and other purposes. It has been previously shown that a bioinspired polarization-difference imaging (PDI) technique can facilitate detection and feature extraction of targets in scattering media. It has also been established [J. Opt. Soc. Am. A 15, 359 (1998)] that polarization sum and polarization difference are the optimum pair of linear combinations of images taken through two orthogonally oriented linear polarizers of a scene having a uniform distribution of polarization directions. However, in many real environments the scene has a nonuniform distribution of polarization directions. Using principal component analysis of the polarization statistics of the scene, we develop a method to determine the two optimum information channels with unequal weighting coefficients that can be formed as linear combinations of the images of a scene taken through a pair of linear polarizers not constrained to the horizontal and vertical directions of the scene. We determine the optimal orientations of linear polarization filters that enhance separation of a target from the background, where the target is defined as an area with distinct polarization characteristics as compared to the background. Experimental results confirm that in most situations adaptive PDI outperforms conventional PDI with fixed channels.

Journal Article↗
PubMed1989

On statistical methods for analysing the geographical distribution of cancer cases near nuclear installations.

There is great public concern, often based on anecdotal reports, about risks from ionising radiation. Recent interest has been directed at an excess of leukaemia cases in the locality of civil nuclear installations at Sellafield and Sizewell, and epidemiologists have a duty to pursue such information vigorously. This paper sets out to show that the epidemiological methods most commonly used can be improved upon. When analysing geographical data it is necessary to consider location. The most obvious quantification of location is ranked distance, though other measures which may be more meaningful in relation to aetiology may be substituted. A test based on distance ranks, the "Poisson maximum test", depends on the maximum of observed relative risk in regions of increasing size, but with significance level adjusted for selection. Applying this test to data from Sellafield and Sizewell shows that the excess of leukaemia incidence observed at Seascale, near Sellafield, is not an artefact due to data selection by region, and that the excess probably results from a genuine, if as yet unidentified cause (there being little evidence of any other locational association once the Seascale cases have been removed). So far as Sizewell is concerned, geographical proximity to the nuclear power station does not seem particularly important.

Cluster Analysis↗
PubMed2004

Estimating vital statistics and age distributions of measurable soil organic carbon fractions based on their pathway of formation and radiocarbon content.

Radiocarbon measurements have been used in combination with "bomb 14C" models to estimate turnover of soil organic carbon fractions. However, the bomb 14C models assume that all SOC fractions are formed directly from external inputs of carbon, which is not always valid because some SOC fractions may receive carbon from other SOC fractions. Due to the continuous inputs of organic carbon, we argue that the most appropriate way to describe the age of SOC is by an age distribution. We developed age distributed models of SOC fractions and derived analytical solutions to them. The models all assume that SOC fraction decay can be described by first-order kinetics, but differ in their assumptions about the pathway of SOC fraction formation. The solutions can be used to estimate age distributions at steady state of different SOC fractions based on their radiocarbon content. These age distributions can be used to calculate the mean age, mean residence time, and other vital statistics of each measurable SOC fraction. Furthermore, if a sequential scheme is used to isolate the SOC fractions, an estimated age distribution of the total SOC can be obtained by adding the contributions of each soil fraction. The age distributions can be very helpful in interpretations of soil organic carbon dynamics in different soils.

Carbon Radioisotopes↗
PubMed1980

[Statistical method of determining distribution of foci in infectious diseases].

Primary infections in organized groups have been found to correspond to the Poisson distribution. This fact is the basis of the statistical method for determination of lhe distribution of foci, the equation is proposed wherein the following data are used: the total number of cases, the total number of organized groups, the number of groups tree of infection, the average size of a group, and the time of observations. The use of foci distribution index for the statistical determination of distribution of foci in varicelfa and parotitis has allowed the author to reveal regularities characteristic of the epidemic process in these infections.

Communicable Diseases↗
PubMed1989

[A statistical study on distribution patterns of plasma free amino acids].

We investigated the distribution patterns of 23 plasma free amino acids in 875 healthy adults (375 males and 500 females, aged from 30 to 50 years), which were obtained after an overnight fast, using three statistical parameters of MLL (Maximum Logarithmic Likelihood), square root of b1, b2, and selected their patterns from the three of ordinary normal, log-normal and square root-normal distributions. The distribution patterns of the majority of plasma free amino acids were found to be either log-normal or square root-normal, and occasionally ordinary normal. We also evaluated the reliability of our selection system by a simulation model of 100 sets of values for plasma free amino acids that were randomly determined by the parameters of original data. Good reliability was observed for some amino acids. Our selection system may be useful for comparing the present results with the future results that will be obtained by other methods.

Adult↗
PubMed2004

Bayesian fluorescence in situ hybridisation signal classification.

Previous research has indicated the significance of accurate classification of fluorescence in situ hybridisation (FISH) signals for the detection of genetic abnormalities. Based on well-discriminating features and a trainable neural network (NN) classifier, a previous system enabled highly-accurate classification of valid signals and artefacts of two fluorophores. However, since this system employed several features that are considered independent, the naive Bayesian classifier (NBC) is suggested here as an alternative to the NN. The NBC independence assumption permits the decomposition of the high-dimensional likelihood of the model for the data into a product of one-dimensional probability densities. The naive independence assumption together with the Bayesian methodology allow the NBC to predict a posteriori probabilities of class membership using estimated class-conditional densities in a close and simple form. Since the probability densities are the only parameters of the NBC, the misclassification rate of the model is determined exclusively by the quality of density estimation. Densities are evaluated by three methods: single Gaussian estimation (SGE; parametric method), Gaussian mixture model assuming spherical covariance matrices (GMM; semi-parametric method) and kernel density estimation (KDE; non-parametric method). For low-dimensional densities, the GMM generally outperforms the KDE that tends to overfit the training set at the cost of reduced generalisation capability. But, it is the GMM that loses some accuracy when modelling higher-dimensional densities due to the violation of the assumption of spherical covariance matrices when dependent features are added to the set. Compared with these two methods, the SGE and NN provide inferior and superior performance, respectively. However, the NBC avoids the intensive training and optimisation required for the NN, demanding extensive resources and experimentation. Therefore, when supporting these two classifiers, the system enables a trade-off between the NN performance and NBC simplicity of implementation.

Algorithms↗
PubMed1981

Brazil.

Explore the source record for details and available documents.

Age Distribution↗
PubMed2005

[A method for the medical image registration based on the statistics samples averaging distribution theory].

The registration method based on mutual information is currently a popular technique for the medical image registration, but the computation for the mutual information is complex and the registration speed is slow. In engineering process, a subsampling technique is taken to accelerate the registration speed at the cost of registration accuracy. In this paper a new method based on statistics sample theory is developed, which has both a higher speed and a higher accuracy as compared with the normal subsampling method, and the simulation results confirm the validity of the new method.

Algorithms↗
PubMed1983

Scandinavia.

Explore the source record for details and available documents.

Age Distribution↗
PubMed2003

Clinical responses to tumor necrosis factor alpha antagonists do not show a bimodal distribution: data from the Stockholm tumor necrosis factor alpha followup registry.

OBJECTIVE: To study the distribution of clinical responses to treatment with the tumor necrosis factor alpha (TNFalpha) antagonists etanercept and infliximab, and in particular, to determine whether there is a biologically meaningful distinction between responders and nonresponders. METHODS: Among patients in the Stockholm TNFalpha Followup Registry, we analyzed the clinical responses to etanercept and infliximab, using the American College of Rheumatology (ACR) core set of outcome measures. For each parameter, the absolute change (value at baseline - current value) and the percentage change ([absolute change]/[value at baseline] x 100) from baseline were calculated. The results were plotted as histograms and inspected visually, and the distributions were statistically compared with computer-generated normal distributions. RESULTS: Absolute and relative changes in outcomes on the ACR core set of measures in 406 patients receiving etanercept or infliximab were studied. All but a few of these analyses yielded normal or somewhat skewed distributions. The statistical analyses did not detect any non-normal distributions, and visually, the distributions did not appear to be bimodal. CONCLUSION: The clinical response to TNFalpha blockade displays a normal or skewed, but not bimodal, distribution. The frequently encountered perception that a clear distinction can be made between responders and nonresponders is not borne out. These relatively straightforward findings imply that the biologic mechanisms determining responsiveness to TNFalpha blockade are multifactorial and may also have important implications for regulatory guidelines pertaining to treatment with these biologic agents.

Antibodies, Monoclonal↗
PubMed1985

The statistical analysis of distribution of blood deposits in arterial prostheses after short-term exposure to reduced blood flow in dogs: a computerized study using radioisotopes.

This study was undertaken to analyse the distribution pattern of blood elements deposits in 15 cases of vascular prostheses submitted, ex vivo, to reduced blood flow in a canine model. Autologous blood platelets labeled with Indium-111 and human 125 Iodinated fibrinogen were injected into the animals. Ten minutes later, the blood flow in the aorta was reduced to 50 ml/min and the prostheses (Woven DeBakey, 30 cm long and 6 mm internal diameter), were implanted as substitutes for the infrarenal abdominal aorta. The blood flow was then reestablished to 50 ml/min and controlled throughout the entire experiment. When a thrombosis occurred, or after 4 hours of low blood circulation, the prosthesis was collected, weighted and chemically fixed, and the radioactivity was measured by means of a two-channel gamma scintillation counter. These data were then formatted and processed by a special computer program. Final values were processed for graphical representation and analysed statistically. Results show a lack of correlation between weight of thrombotic matrix, platelet accumulation, and fibrin deposits retained from one animal to the other. There is, though, an appearance of a complex interrelationship between the mean pattern of longitudinal distribution of these elements, which shall be qualified as contagious distal accumulation of the deposits. The influence of each animals' blood characteristics, as evaluated by means of regression analysis, account for 40 to 60% of the interindividual variance in blood deposits. Data corrections following evidence of undesirable influences due to uncontrolled parameters are presented. This experimental method permits simultaneous graphical representation of the distribution of several elements in the thrombotic matrix, and at the same time an elaborate numerical analysis of their longitudinal distribution and total accumulation. The method is easy to use, does not require sophisticated equipment, and is less expensive than scintigraphy.

Animals↗