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At least 595 records · Page 33Linked to original sources
PubMedDate not supplied

[Method of computing positive pressure in the human lung following space cabin decompression].

The paper presents a mathematical model and differential equations to be used in computer-aided estimations of the positive pressure in human lugs upon space cabin blast decompression. The paper gives a simplified method of computing the pressure which utilizes a special diagram of decompression of a rigid container communicating with the cabin through a hole of a constant area. The characteristic feature of the method is a simultaneous computation of the air outflowing from the lungs and their expansion during decompression. The paper illustrates the advantage of the simultaneous computation of the processes and specifies the pulmonary regions of positive pressure at given blast decompressions. The paper compares theoretical and experimental (data by foreign researchers) peak values of the positive pressure in human lungs during blast decompression, indicating good agreement of the results.

Atmospheric Pressure↗
PubMed1997

A computer-assisted method for the determination of hair cuticula patterns in mammals.

The study describes a rather simple, computer-assisted method for the determination of different mammalian species or groups with the aid of the cuticula pattern of guard hairs (primary hairs) following SEM presentation. The method is based on an image analysis program developed for metallographic investigations, and includes the evaluation of five parameters (scale area, scale perimeter, number of scales per mm2, ratio of scale width and height, scale index). The scale index as a combination of scale numbers per square unit and the width/height ratio proved to be most useful for a relevant species or group identification of mammals according to the hair cuticula pattern.

Animals↗
PubMed1975

Computer-based method for calculation of the available energy of proteins.

An aspect of protein nutrition that has not been resolved in a satisfactory manner is the utilizable energy equivalence of proteins. The existing methods overestimate the utilizable energy of proteins. A more accurate method fo calculating the utilizable energy of proteins is to calculate the moles of adenosine triphosphate formed during the complete oxidation of a given amount of proteins. The moles of adenosine triphosphate formed can be calculated from knowledge of the amino acid composition and knowledge of the metabolic pathway for each amino acid. A computer program is described that provides the bookkeeping required for these calculations. The available energy of a protein is calculated in this computer-based method by adjusting the energy value of the proteins so that it is equivalent to that of carbohydrates and fats in providing the energy for adenosine triphosphate formation. The computer-based method was used to calculate the available energy of a group of proteins of known amino acid composition. The available energy varied from 3.02 keal/g for colagen to 3

Adenosine Triphosphate↗
PubMed2006

Fast and efficient method for computing ART.

Angular radial transform (ART), which is the region-based shape descriptor of MPEG-7, has desirable properties for representing shape information in a small number of features with no redundancy. However, in order for ART to be useful, especially in limited computing environments, the computational cost of ART must be greatly reduced. In this paper, we derive symmetric/antisymmetric properties from the basis functions of ART and present a fast and efficient method to compute the ART coefficients using these properties. The proposed method significantly reduces the number of sinusoidal operations and multiplications in computing the coefficients of ART. Moreover, the memory requirements needed to store the ART basis functions in lookup tables are only 25% of the conventional method. The experimental results are presented to show the effectiveness of the proposed method.

Algorithms↗
PubMed2006

Particle method for computer simulation of red blood cell motion in blood flow.

A particle method for the computer simulation of blood flow was proposed to analyze the motion of a deformable red blood cell (RBC) in flowing blood plasma. The RBC and plasma were discretized by particles that have the characteristics of an elastic membrane and a viscous fluid, respectively. The membrane particles were connected to their neighboring membrane particles by springs, and the motion of the particles was determined on the basis of the minimum energy principle. The incompressible flow of plasma that was expressed by the motion of the fluid particles was determined by the moving-particle semi-implicit (MPS) method. The RBC motion and plasma flow were weakly coupled. The two-dimensional simulation of blood flow between parallel plates demonstrated the capability of the proposed method to express the blood flow phenomena observed in experiments, such as the downstream motion of the RBC and the deformation of the RBC into a parachute shape.

Blood Circulation↗
PubMed1985

Methods for computing the standard errors of branching points in an evolutionary tree and their application to molecular data from humans and apes.

Statistical methods for computing the standard errors of the branching points of an evolutionary tree are developed. These methods are for the unweighted pair-group method-determined (UPGMA) trees reconstructed from molecular data such as amino acid sequences, nucleotide sequences, restriction-sites data, and electrophoretic distances. They were applied to data for the human, chimpanzee, gorilla, orangutan, and gibbon species. Among the four different sets of data used, DNA sequences for an 895-nucleotide segment of mitochondrial DNA (Brown et al. 1982) gave the most reliable tree, whereas electrophoretic data (Bruce and Ayala 1979) gave the least reliable one. The DNA sequence data suggested that the chimpanzee is the closest and that the gorilla is the next closest to the human species. The orangutan and gibbon are more distantly related to man than is the gorilla. This topology of the tree is in agreement with that for the tree obtained from chromosomal studies and DNA-hybridization experiments. However, the difference between the branching point for the human and the chimpanzee species and that for the gorilla species and the human-chimpanzee group is not statistically significant. In addition to this analysis, various factors that affect the accuracy of an estimated tree are discussed.

Amino Acid Sequence↗
PubMed2000

Analysis of the direct Fourier method for computer tomography.

We develop a direct Fourier method (DFM) for reconstructing a function from its X-ray projections. We introduce a framework that can be used to get a quantitative comparison between different choices of basis functions in the step of resampling from polar to Cartesian coordinates. We use the framework to compare polynomial interpolation, approximated sinc-functions, Gaussians, splines, and Kaiser-Bessel functions. The resulting algorithm is very fast, requiring 12.5N2 log2 N + 49N2 flops. Numerical experiments show it to be efficient.

Algorithms↗
PubMed1977

A standardized method for computed tomography of the orbits.

A standardized method for the CT exploration of the orbital region has been searched for. This method makes it possible to visualize the entire orbital region with a minimum of 4 tomographic scans, each section 6 mm thick. The reference line chosen for this exploration is parallel to the optic nerve and joins the projection of the inferior border of the orbit on the lateral view with the upper border of the ear to the scalp. After each tomographic scan the patient is moved so that the new scanning line is still parallel to the reference line but distant by 9 mm from the previous one.

Humans↗
PubMed1989

Strategies for the use of computational SAR methods in assessing genotoxicity.

The relationship between computational SAR studies and relevant data gathering and generation activities is complex. First, the chemical class to be studied is selected on the basis of information requirements for hazard identification and assessment. Membership in the class is determined by consideration of chemical structure and reactivity. Compilation of the existing bioassay data for this chemical class follows immediately from the specification of the class. Bioassay data, qualitative knowledge of general chemical reactivities in this class, and knowledge concerning potential interactions with biomolecular targets all contribute to the derivation of possible mechanisms for biological activity. Computational studies based on modeling the proposed mechanism of action and/or the existing data base can provide a quantitative basis for the differentiation between chemicals. There is the opportunity for continuing feedback between the quantitative computational studies and the development of a relevant bioassay data base for this chemical class. The qualitative and quantitative information on the potential biological responses obtained will provide a rational basis for extrapolation from the extant data base to the chemicals of interest, and to biological responses significant to the assessment for which complete data are unavailable. Knowledge concerning possible mechanisms of action and preexisting data determine the type of computational study that will be most useful.

Animals↗
PubMed1996

Facing future challenges in general practice: a clinical method with computer support.

This paper proposes a clinical method for general practice which is patient-centred and which ensures that the doctor's agenda is supported to secure 'best practice'. It encompasses self-learning for GPs which is patient-focused and describes the encouragement and support of patient self-care. The method attempts to be pragmatic and usable within GPs' available time. The method, however, is not solely focused on the GP; it encompasses the primary health care team and the patient. It uses clinical information systems to assist in the management of the patient care plan, to supply information to the GP and patient, in order to aid shared decision making and to quality assure clinical activity. It goes further by extending the care process to handle 'virtual' encounters in which the clinical information systems play a central role.

Education, Medical, Continuing↗
PubMedDate not supplied

Validation of a new counts-based gated single photon emission computed tomography method for quantifying left ventricular systolic function: comparison with equilibrium radionuclide angiography.

BACKGROUND: Because myocardial wall thickness is smaller than the spatial resolution of single photon emission computed tomography (SPECT) imaging, changes in myocardial wall thickness are related to changes in maximum pixel counts via the partial volume effect, allowing for quantification of regional systolic wall thickening. We have developed a new gated SPECT method for computing the global left ventricular ejection fraction (LVEF) based entirely on changes in maximum regional myocardial counts during systolic contraction. This new method is independent of endocardial edge detection or other geometric measurements. METHODS AND RESULTS: In 23 patients the gated SPECT method was validated by comparison with radionuclide angiography. The correlation between computed LVEFs was excellent (slope = 0.97, r = 0.91). The measurement of LVEF by gated SPECT was highly reproducible, with minimal intraoperator (slope = 0.97, r = 0.97) or interoperator (slope = 1.00, r = 0.97) variability. Measurements of regional thickening indexes were also reproducible, with a mean intraoperator correlation coefficient of 0.89 +/- 0.05 (range 0.79 to 0.95) for the 14 myocardial regions. Finally, the measurement of LVEF was not significantly influenced by changes in reconstruction filter parameters over a range of cutoff frequencies from 0.16 to 0.28. CONCLUSIONS: This new counts-based gated SPECT method for measuring global left ventricular systolic function correlates well with radionuclide angiography, is highly reproducible, and has theoretic advantages over geometric methods.

Adult↗
PubMedDate not supplied

Validation of a computer-assisted method for estimating the number and volume of gallstones visualized by cholecystography.

It is likely that in the near future there will be widespread use of medicinal therapy to dissolve gallstones. The efficacy of medicinal therapy can best be determined by attempting to relate the total surface area of a collection of gallstones to the composition of bile in patients undergoing therapy. Surface area, in turn, can be directly related to gallstone size and number. In this study, involving 48 cholecystectomized patients, we have shown that standard cholecystography, together with a computer-assisted method of metrology, can effectively monitor the above parameters. Determinations of the standard deviation of 1) replicate readings (35.8%) and 2) averaged metrology estimates compared with actual stone volumes (42.9%), as well as correlation of actual stone volumes with averaged metrology estimates (r = 0.961), indicated the magnitude of assessed change in stone volume that would be necessary to accept a roentgenographic decrease or increase in stone size with 95% confidence. Even with the increased precision found in the computer-assisted method as described, to attain a 98% certainty of some volume change it was necessary to have metrology volume change of 50% or more. Actual stone counts were without significant error in 87.5% of the determinations.

Chenodeoxycholic Acid↗
PubMed1993

Computer-aided methods for evaluating cancer risk in miners due to radiation exposure.

The paper presents some aspects of radiation hazard which occurs in a non-nuclear sector of industry, namely radiation hazard in non-uranium underground mines. The radiation hazard is caused in each type of underground mine by the naturally occurring noble radioactive gas-radon (222Rn) and radioactive products of its decay 218Po, 214Pb, 214Bi/214Po the so-called 'radon daughters' occurring in the mines' air. The paper presents the concept of how to provide a reliable system of assessment of miners' exposure by application of representative individual dosimetry, and also presents principles of computer-aided methods for interpretation of the results of miner's dosimetry useful for conversion of dosimetry data to the term of expected risk of cancer caused by exposure at miner's workplaces. The representative Individual Dosimetry system strengthened by computer-aided methods of analysis of results provided essential information on radiation cancer risk for miners employed in coal mines, metal-ore mines, chemical raw material mines in Poland. The coefficient of annual cancer risk induction is 1.5 x 10(-4) year-1 for coal mines, 1.40 x 10(-4) year-1 for metal ore mines and 1.5 x 10(-4) year-1 for chemical raw material mines. The radiation risk appears to be of the same magnitude as the conventional risk of life loss at work-related accidents. The average Lost Life Expectancy coefficient for both the radiation risk and conventional risk are 0.5 and 0.3 year per each miner, respectively.

Electronic Data Processing↗
PubMed2004

Enhanced functional information from predicted protein networks.

Experimentally derived genome-wide protein interaction networks have been useful in the elucidation of functional information that is not evident from examining individual proteins but determination of these networks is complex and time consuming. To address this problem, several computational methods for predicting protein networks in novel genomes have been developed. A recent publication by Date and Marcotte describes the use of phylogenetic profiling for elucidating novel pathways in proteomes that have not been experimentally characterized. This method, in combination with other computational methods for generating protein-interaction networks, might help identify novel functional pathways and enhance functional annotation of individual proteins.

Energy Metabolism↗
PubMed2002

Designing gene libraries from protein profiles for combinatorial protein experiments.

Protein combinatorial libraries provide new ways to probe the determinants of folding and to discover novel proteins. Such libraries are often constructed by expressing an ensemble of partially random gene sequences. Given the intractably large number of possible sequences, some limitation on diversity must be imposed. A non-uniform distribution of nucleotides can be used to reduce the number of possible sequences and encode peptide sequences having a predetermined set of amino acid probabilities at each residue position, i.e., the amino acid sequence profile. Such profiles can be determined by inspection, multiple sequence alignment or physically-based computational methods. Here we present a computational method that takes as input a desired sequence profile and calculates the individual nucleotide probabilities among partially random genes. The calculated gene library can be readily used in the context of standard DNA synthesis to generate a protein library with essentially the desired profile. The fidelity between the desired profile and the calculated one coded by these partially random genes is quantitatively evaluated using the linear correlation coefficient and a relative entropy, each of which provides a measure of profile agreement at each position of the sequence. On average, this method of identifying such codon frequencies performs as well or better than other methods with regard to fidelity to the original profile. Importantly, the method presented here provides much better yields of complete sequences that do not contain stop codons, a feature that is particularly important when all or large fractions of a gene are subject to combinatorial mutation.

Amino Acids↗
PubMedDate not supplied

Evaluation of computational chemistry methods: crystallographic and cheminformatics analysis of aminothiazole methoximes.

Cheminformatics is used to validate the capabilities of widely used quantum chemistry and molecular mechanics methods. Among the quantum methods examined are the semiempirical MNDO, AM1, and PM3 methods, Hartree-Fock (ab initio) at a range of basis set levels, density functional theory (DFT) at a range of basis sets, and a post-Hartree-Fock method, local Moller-Plesset second-order perturbation theory (LMP2). Among the force fields compared are AMBER, MMFF94, MMFF94s, OPLS/A, OPLS-AA, Sybyl, and Tripos. Programs used are Spartan, MacroModel, SYBYL, and Jaguar. The test molecule is (2-amino-5-thiazolyl)-alpha-(methoxyimino)-N-methylacetamide, a model of the aminothiazole methoxime (ATMO) side chain of third-generation cephalosporin antibacterial agents. The Ward hierarchical clustering technique yields an insightful comparison of experimental (X-ray) and calculated (energy optimized) bond lengths and bond angles. The computational chemistry methods are also compared in terms of the potential energy curves they predict for internal rotation. Clustering analysis and regression analysis are compared. The MMFF94 force field such as implemented in MacroModel is the best overall computational chemistry method at reproducing crystallographic data and conformational properties of the ATMO moiety. This work demonstrates that going to a higher level of quantum theory does not necessarily give better results and that quantum mechanical results are not necessarily better than molecular mechanics results.

Journal Article↗
PubMed2003

Computer-aided method for quantification of cartilage thickness and volume changes using MRI: validation study using a synthetic model.

The primary objective of this study was to develop a computer-aided method for the quantification of three-dimensional (3-D) cartilage changes over time in knees with osteoarthritis (OA). We introduced a local coordinate system (LCS) for the femoral and tibial cartilage boundaries that provides a standardized representation of cartilage geometry, thickness, and volume. The LCS can be registered in different data sets from the same patient so that results can be directly compared. Cartilage boundaries are segmented from 3-D magnetic resonance (MR) slices with a semi-automated method and transformed into offset-maps, defined by the LCS. Volumes and thickness are computed from these offset-maps. Further anatomical labeling allows focal volumes to be evaluated in predefined subregions. The accuracy of the automated behavior of the method was assessed, without any human intervention, using realistic, synthetic 3-D MR images of a human knee. The error in thickness evaluation is lower than 0.12 mm for the tibia and femur. Cartilage volumes in anatomical subregions show a coefficient of variation ranging from 0.11% to 0.32%. This method improves noninvasive 3-D analysis of cartilage thickness and volume and is well suited for in vivo follow-up clinical studies of OA knees.

Algorithms↗