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PubMed1991

Assessment of inhomogeneities in an E. coli physical map.

A statistical method based on r-fragments, sums of distances between (r + 1) consecutive restriction enzyme sites, is introduced for detecting nonrandomness in the distribution or too markers in sequence data. The technique is applicable whenever large numbers of markers are available and will detect clumping, excessive dispersion or too much evenness of spacing of the markers. It is particularly adapted to varying the scale on which inhomogeneities can be detected, from nearest neighbor interactions to more distant interactions. The r-fragment procedure is applied primarily to the Kohara et al. (1) physical map of E. coli. Other applications to DAM methylation sites in E. coli and NotI sites in human chromosome 21 are presented. Restriction sites for the eight enzymes used in (1) appear to be randomly distributed, although at widely differing densities. These conclusions are substantially in agreement with the analysis of Churchill et al. (3). Extreme variability in the density of the eight restriction enzyme sites cannot be explained by variability in mono-, di- or trinucleotide frequencies.

Base Sequence↗
PubMed1984

Stability distribution in the phage lambda-DNA double helix: a correlation between physical and genetic structure.

Statistical analyses on the positional correlation of physical-stability and base-sequence distribution maps with genetic map are made for the whole DNA (48502 bases) of lambda-phage. The susceptibility to a double-helix unfolding perturbation and the fraction of the transient opening of a particular region of the double helix are adopted to define this physical stability. The principal features obtained are: A) The DNA double strand of protein coding regions is found to have homostabilizing propensity around a defined stability which is characteristic to each individual gene. B) The stability of the double helix in non-protein coding region fluctuates, on average over the whole region, more than that in protein coding region. C) Boundary regions of protein coding and non-protein coding regions are regions of high stability-fluctuation. Stability especially fluctuates at the protein-coding-region side of the boundary. Contrary to the quiet feature of the interior part of protein coding region rather noisy part exists at its edge. D) One frequently opening region coincides with the attaching site for the site specific recombination between phage and bacterial DNA. There are two possible ways to explain the noisy feature in the stability distribution in non-protein coding regions: 1) The region has been used as the locus of recombination as evolution took place. Thus DNAs which were homostabilized around a different value characteristic to each individual DNA, have been joined there many times, so that the noise has accumulated as a remnant of evolutional history; and/or 2) the base-composition homogenizing or double-helix homostabilizing mechanism does not work in unneeded region such as non-protein coding region or introns. Since corresponding characteristics have been found in our previous analyses on other viral and globin-gene DNAs, the rules mentioned above may be comprehensively extended to other DNAs.

Bacteriophage lambda↗
PubMed1977

Physics of chemoreception.

Statistical fluctuations limit the precision with which a microorganism can, in a given time T, determine the concentration of a chemoattractant in the surrounding medium. The best a cell can do is to monitor continually the state of occupation of receptors distributed over its surface. For nearly optimum performance only a small fraction of the surface need be specifically adsorbing. The probability that a molecule that has collided with the cell will find a receptor is Ns/(Ns + pi a), if N receptors, each with a binding site of radius s, are evenly distributed over a cell of radius a. There is ample room for many indenpendent systems of specific receptors. The adsorption rate for molecules of moderate size cannot be significantly enhanced by motion of the cell or by stirring of the medium by the cell. The least fractional error attainable in the determination of a concentration c is approximately (TcaD) - 1/2, where D is diffusion constant of the attractant. The number of specific receptors needed to attain such precision is about a/s. Data on bacteriophage absorption, bacterial chemotaxis, and chemotaxis in a cellular slime mold are evaluated. The chemotactic sensitivity of Escherichia coli approaches that of the cell of optimum design.

Bacterial Physiological Phenomena↗
PubMed2004

Trauma and dissociation in conversion disorder and chronic pelvic pain.

OBJECTIVE: The purpose of this study was to: a) assess the link between sexual and/or physical abuse and dissociation in conversion disorder and chronic pelvic pain patients; and b) assess whether this effect is independent of level of general psychopathology. METHOD: This report examines data from four separate samples. Fifty-two patients with chronic pelvic pain, 61 patients with non-epileptic seizures, and two samples of patients (102 and 54) with predominantly motor or sensory types of conversion disorder were studied. RESULTS: Using point-biserial correlations no compelling evidence for a consistent and positive association of sexual and/or physical abuse with dissociation was found. After statistically controlling for level of psychopathology using multiple regression analyses, in most of the cases the association of abuse with dissociation was no longer statistically significant. Only physical abuse predicted level of somatoform dissociation over and above level of psychopathology. CONCLUSION: In future clinical studies of dissociation in patients with conversion disorder and chronic pelvic pain more complex models may be needed with less exclusive reliance on historical antecedents such as childhood abuse and more emphasis on recent potentially traumatizing experiences or co-morbid psychiatric disorders.

Adult↗
PubMedDate not supplied

Lognormal distribution in physical work capacity in young healthy males.

This paper evaluates the statistical distribution of physical work capacity (Vo2 max) in young healthy males. For this purpose, the normally of Vo2 max data, collected on two random samples consisting of 123 and 120 young healthy male volunteers was tested. It is concluded that physical work capacity follows lognormal distribution and the quality of fit has been found to be good as tested by chi2 test.

Disability Evaluation↗
PubMed2002

Physical activity and colon cancer: confounding or interaction?

PURPOSE: Although physical activity has been consistently inversely associated with colon cancer incidence, the association of physical activity with other diet and lifestyle factors that may influence this association is less well understood. Confounding and effect modification are examined to better understand the physical activity and colon cancer association. METHODS: Based on hypothesized biological mechanisms whereby physical activity may alter risk of colon cancer, we evaluated confounding and effect modification using data collected as part of a case-control study of colon cancer (N = 1993 cases and 2410 controls). We examined associations between total energy intake, fiber, calcium, fruit and vegetables, red meat, whole grains as well as dietary patterns along with cigarette smoking, alcohol consumption, BMI, and use of aspirin and/or NSAIDs and physical activity. RESULTS: No confounding was observed for the physical activity and colon cancer association. However, differences in effects of diet and lifestyle factors were identified depending on level of physical activity. Most striking were statistically significant interactions between physical activity and high-risk dietary pattern and vegetable intake, in that the relative importance of diet was dependent on level of physical activity. The predictive model of colon cancer risk was improved by using an interaction term for physical activity and other variables, including BMI, cigarette smoking, energy intake, dietary fiber, dietary calcium, glycemic index, lutein, folate, vegetable intake, and high-risk diet rather than using models that included these variables as independent predictors with physical activity. In populations where activity levels are high, the estimate of risk associated with high vegetable intake was 0.9 (95% CI 0.6-1.3), whereas in more sedentary populations the estimate of risk associated with high vegetable intake was 0.6 (95% CI 0.5-0.9). CONCLUSIONS: Physical activity plays an important role in the etiology of colon cancer. Its significance is seen by its consistent association as an independent predictor of colon cancer as well as by its impact on the odds ratios associated with other factors. Given these observations, it is most probable that physical activity operates through multiple biological mechanisms that influence the carcinogenic process.

Adult↗
PubMed1986

[Effect of diet and exercise therapy on body weight, performance and lipid metabolism of post-infarct patients during a 4-week rehabilitation program].

From a total of 130 male patients following myocardial infarction a symptom-limited stress cycling ergometer was carried out at the beginning as well as at the end of a 4-week rehabilitation, as well as controls of body weight, the Broca-Index, and Triglyzeride, Cholesterol, HDL-Cholesterol, LDL-Cholesterol and VLDL-Cholesterol fractions. With regard to the Broca-Index, the patients received respectively a 1600 Kcal normal diet (Broca-Index 1.00, n = 34), a 1100 Kcal reductional diet (Broca-Index 1.20, n = 67) and a 600 Kcal reductional diet (Broca-Index 1.32, n = 29). During the whole duration of their stay, the patients underwent a program of physical exercise related to their personal physical performance, which consisted of gymnastic, cycle training, swimming (facultative) and physical training. The improvements of the physical performance were statistically significant, and consisted of 19.4% (normal diet), 18.2% (1100 Kcal diet), namely 11.3% in the 600 Kcal diet group. Weight, Broca-Index and parameters of fat-metabolism remained unchanged under a normal diet. In both reductional diet groups a significant reduction of weight and Broca-Index as well as all blood-fat-metabolism parameters were noted, with the exception of the HDL-Cholesterol fraction, which remained unchanged. Statistical significant correlations between weight reduction, namely increases of physical performance and parameters of blood-fat-metabolism were only noted in cases of a 600 Kcal diet. The noted changes in weight, physical performance and blood-fat-metabolism can be considered as a reduction of the cardiovascular risk profile.

Body Weight↗
PubMed1987

Statistical analysis of productivity in one physical therapy department.

The purposes of this retrospective study were to document productivity-relevant measurements, describe the relationships between these measurements, and discuss the implications of the relationships in one physical therapy department. The department's inputs (clinician and staff hours worked), outputs (patient visits, patient procedures, hours charged, and dollars charged), and productivity (staff utilization, financially productive time, and dollars charged per staff hours worked) were monitored. Pearson product-moment correlations, partial correlations, and linear regression statistics were calculated to determine the relationships between the variables measured. During the 30-month period studied, average daily census of the institution decreased, clinician hours worked decreased, patient procedures and dollars charged increased, and the three productivity measures increased. The relationship between output measures and clinician hours worked was apparent only after the effects of increased productivity were controlled. Departmental outputs and productivity were independent of the institution's census. The findings provided no evidence that decisions regarding staffing should be based on institutional census.

Efficiency↗
PubMed2003

Personal, social, and physical environmental correlates of physical activity levels in urban Latinas.

BACKGROUND: Nationwide, Hispanic women report low levels of physical activity and bear excess health risk associated with inactivity. This study investigated the relationship between physical activity levels and sociodemographic, social environmental, and physical environmental factors. DESIGN: A cross-sectional, community-based convenience sample of 285 Hispanic/Latino women completed a face-to-face survey administered in Spanish. MAIN OUTCOME MEASURES: The following categories of physical activity were used in analyses: "meets current national recommendations," which includes women who reported engaging in moderate activity at least 5 days per week for at least 30 minutes or who engaged in vigorous activity at least 3 days per week for at least 20 minutes; "insufficiently active" for women not meeting moderate or vigorous objectives; and "inactive" for women who report no moderate or vigorous physical activity. RESULTS: The majority of women (46%) were aged 20 to 29 years, 48% have less than or equal to a high school education, 72% are employed, 43% speak Spanish, and 76% are from Central or South America. A total of 37% of the women met physical activity recommendations, 23% were inactive, and 40% were insufficiently active. Personal and physical environmental factors were not statistically significant correlates of activity level comparison groups; however, most indicated trends in the hypothesized direction. Social environmental factors that showed statistically significant relationships with various physical activity comparison groups included the following: Women were significantly less likely to be active if they reported knowing people who exercise (odds ratio [OR]=0.42; 95% confidence interval [CI], 0.23-0.76), reported that there are people in the neighborhood who exercise (adjusted OR=0.19; 95% CI, 0.09-0.42), belonged to community groups (OR=0.32; 95% CI, 0.15-0.69), or attended religious services (OR=0.41; 95% CI, 0.41-0.72). CONCLUSION: Social environmental factors appeared to be the most important factors related to physical activity in this group of Latino women. Physical environment and personal factors, although not statistically significant, showed trends in expected directions and should be explored further.

Adult↗
PubMed2000

A review of correlates of physical activity of children and adolescents.

BACKGROUND: Understanding the factors that influence physical activity can aid the design of more effective interventions. Previous reviews of correlates of youth physical activity have produced conflicting results. METHODS: A comprehensive review of correlates of physical activity was conducted, and semiquantitative results were summarized separately for children (ages 3-12) and adolescents (ages 13-18). The 108 studies evaluated 40 variables for children and 48 variables for adolescents. RESULTS: About 60% of all reported associations with physical activity were statistically significant. Variables that were consistently associated with children's physical activity were sex (male), parental overweight status, physical activity preferences, intention to be active, perceived barriers (inverse), previous physical activity, healthy diet, program/facility access, and time spent outdoors. Variables that were consistently associated with adolescents' physical activity were sex (male), ethnicity (white), age (inverse), perceived activity competence, intentions, depression (inverse), previous physical activity, community sports, sensation seeking, sedentary after school and on weekends (inverse), parent support, support from others, sibling physical activity, direct help from parents, and opportunities to exercise. CONCLUSION: These consistently related variables should be confirmed in prospective studies, and interventions to improve the modifiable variables should be developed and evaluated.

Adolescent↗
PubMed1994

Design and analysis of chromosome physical mapping experiments.

Mathematical and statistical aspects of constructing ordered-clone physical maps of chromosomes are reviewed. Three broad problems are addressed: analysis of fingerprint data to identify configurations of overlapping clones, prediction of the rate of progress of a mapping strategy and optimal design of pooling schemes for screening large clone libraries.

Chromosome Mapping↗
PubMed1975

Deuterium order parameters in relation to thermodynamic properties of a phospholiped bilayer. A statistical mechanical interpretation.

The physical properties of bilayers of dipalmitoyl-3-sn-phosphatidylcholine are analyzed in terms of a statistical model proposed by Marcelja (S. Marcelja (1974), Biochim. Biophys. Acta 367, 165). The model is used to calculate the segmental order parameters of the hydrocarbon chains, the transition temperature of the crystalline leads to liquid crystalline phase transition, the entropy change of the transition, the bilayer thickness, and the linear thermal expansion coefficient. The theoretical predictions are in excellent agreement with experimental results obtained by deuterium magnetic resonance, differential scanning calorimetry, and X-ray diffraction. The model yields the probabilities of trans and gauche conformations and also those of more specific conformational defects like kinks or jogs.

Calorimetry↗
PubMed2004

Estimation of gait cycle characteristics by trunk accelerometry.

This study reports on the novel use of a portable system to measure gait cycle parameters. Measurements were made by a triaxial accelerometer over the lower trunk during timed walking over a range of self-administered speeds. Signals from each trial were transformed to a horizontal-vertical coordinate system and analyzed by an unbiased autocorrelation procedure to obtain cadence, step length, and measures of gait regularity and symmetry. By curvilinear interpolation, speed-dependent gait parameters could be compared at a normalized speed. It was demonstrated that analysis of gait cycle parameters which previously required fixed laboratory equipment and paced walking procedures, now can be made from data obtained by a timing device and a portable sensor at free walking speeds.

Abdomen↗
PubMed2003

Prevalence of sexual and physical abuse and its relationship with symptom manifestations in patients with chronic organic and functional gastrointestinal disorders.

UNLABELLED: A history of physical and/or sexual abuse is a frequent occurrence in patients referred for chronic gastrointestinal disorders and it may predispose to the development of functional gastrointestinal disorders, and multiple medical complaints. This study was aimed to determine: (a) prevalence of abuse history in Italian patients with chronic gastrointestinal disturbances, and (b) relationship between abuse history and clinical manifestations. SUBJECTS AND METHODS: Consecutive gastrointestinal out-patients filled in a self-administered standardised questionnaire, made up of two separate sections: (1) a medical section enquiring on gastrointestinal and extra-gastrointestinal symptoms, and (2) a section on abuse enquiring on the presence and type of abuse suffered during their lifetime. Associations between number of symptoms and abuse history were evaluated using univariate and multivariate logistic models. RESULTS: Questionnaires were handed out to 260 patients; 13% of whom did not fill in the questionnaires. Functional gastrointestinal disorders were diagnosed in 72.5% of patients and organic gastrointestinal diseases in 27.5%. A total of 31% of patients with organic gastrointestinal diseases and 32% of those with functional gastrointestinal disorders referred to a history of sexual or physical abuse. Histories of physical plus sexual abuse, sexual abuse, childhood abuse and female gender, were statistically associated with an increased number of gastrointestinal and extra-gastrointestinal symptoms irrespective of functional or organic disorders, whereas there was no statistical association with physical abuse only. Furthermore, diagnosis of functional gastrointestinal disorders was associated with a significantly (p<0.001) greater number of gastrointestinal symptoms than the diagnosis of organic gastrointestinal diagnosis. A total of 10 patients met the diagnostic criteria of somatization disorder. Of these, eight reported a history of severe physical and sexual abuse that had occurred, in all but one, during childhood. CONCLUSIONS: A history of physical and/or sexual abuse has a high prevalence in Italian patients with chronic gastrointestinal disorders, irrespective of organic or functional diagnosis. Abuse history has no relevant role in the pathogenesis of either functional or organic chronic gastrointestinal disorders but it can affect their clinical expression irrespective of functional or organic diagnosis. Severe physical and sexual abuse and childhood abuse were found in patients who met diagnostic criteria for somatization disorder, suggesting a role of abuse history in this subset of patients.

Adolescent↗
PubMed2001

Is physical deconditioning a perpetuating factor in chronic fatigue syndrome? A controlled study on maximal exercise performance and relations with fatigue, impairment and physical activity.

BACKGROUND: Chronic fatigue syndrome (CFS) patients often complain that physical exertion produces an increase of complaints, leading to a greater need for rest and more time spent in bed. It has been suggested that this is due to a bad physical fitness and that physical deconditioning is a perpetuating factor in CFS. Until now, studies on physical deconditioning in CFS have shown inconsistent results. METHODS: Twenty CFS patients and 20 matched neighbourhood controls performed a maximal exercise test with incremental load. Heart rate, blood pressure, respiratory tidal volume, O2 saturation, O2 consumption, CO2 production, and blood-gas values of arterialized capillary blood were measured. Physical fitness was quantified as the difference between the actual and predicted ratios of maximal workload versus increase of heart rate. Fatigue, impairment and physical activity were assessed to study its relationship with physical fitness. RESULTS: There were no statistically significant differences in physical fitness between CFS patients and their controls. Nine CFS patients had a better fitness than their control. A negative relationship between physical fitness and fatigue was found in both groups. For CFS patients a negative correlation between fitness and impairment and a positive correlation between fitness and physical activity was found as well. Finally, it was found that more CFS patients than controls did not achieve a physiological limitation at maximal exercise. CONCLUSIONS: Physical deconditioning does not seem a perpetuating factor in CFS.

Activities of Daily Living↗
PubMed2005

Mixed quantum-classical Redfield master equation.

Redfield master equation is derived from mixed quantum-classical Liouville equation using product initial conditions. Simple two-level system example is given and comparison with Fermi golden rule is made.

Algorithms↗