Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “statistical physics”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 667 records · Page 37Linked to original sources
PubMed1998

Evidence that eating frequency is inversely related to body weight status in male, but not female, non-obese adults reporting valid dietary intakes.

OBJECTIVE: To investigate the relationships between eating frequency (EF) and body weight status and to determine whether these relationships can be explained in terms of differences in physical activity levels, macronutrient intakes or energy compensation. DESIGN: Cross-sectional design; free-living subjects, 48 men and 47 women (aged 20-55 y, body mass index (BMI) 18-30), recruited in a workplace setting. MEASUREMENTS: Height and weight; skinfold thickness (four sites); EF, energy and macronutrient intakes (food diary, unweighed, recorded for seven consecutive days); physical activity (7 d activity diary and heart rate monitoring over 48 h period). RESULTS: In men there was a significant negative correlation between EF and body weight, and an inverse relationship with body mass index (BMI). EF was positively correlated with % energy from carbohydrate, although not with total energy intake. In women, there was no relationship between EF and body weight status; however, there were significant positive correlations between EF and total energy intake, and between EF and intakes of total carbohydrate and sugars. For both men and women, there were associations between EF and physical activity levels, approaching statistical significance. CONCLUSIONS: In men, the association between increased EF and lower body weight status may have been influenced by increased physical activity levels. As energy intake did not increase with EF, men appear to have compensated by reducing the mean energy consumed per eating episode. Energy compensation did not take place in women, with women who ate most frequently having the highest energy intakes, although this did not lead to higher BMIs. Physical activity, through participation in active leisure pursuits, may have been an important factor in weight control in women. The % contribution of carbohydrate to total energy was positively correlated with EF in both men and women, and further analysis showed that snack foods provided a higher proportion of carbohydrate than did foods eaten as meals. These results indicate that a high EF is likely to lead to a high carbohydrate diet, which may be favourable for weight control. Our findings suggest that in this population, a high EF was associated with leanness in men, and there was no link between EF and body weight status in women.

Adult↗
PubMed2000

Self-efficacy, activity participation, and physical fitness of asthmatic and nonasthmatic adolescent girls.

The prevalence of asthma, lung self-efficacy beliefs, physical activities, and physical fitness of adolescent girls were studied in a private inner-city high school serving a multiethnic, middle-class population using a questionnaire, a test of physical fitness, and an activity log. Twenty-two percent of the 172 girls were diagnosed with asthma, and an additional 15% of the girls experienced breathing difficulties. It was found that asthmatic girls were less physically fit, reported lower self-efficacy regarding their lung functioning during vigorous activities, and participated less often in those activities than nonasthmatic girls. Perceived lung efficacy was found to predict girls' subsequent participation in physical activities significantly, even when the effects of asthma, smoking, and physical fitness were controlled statistically.

Adolescent↗
PubMed1992

Concordance between clinician and patient assessment of physical and mental health status.

The degree of concordance between clinicians' and patients' assessment of the patient's physical and mental functioning was examined in 166 consecutive eligible outpatients with rheumatoid arthritis (RA) using 4-category ordinal scales. The weighted kappa statistic was 0.39 for physical functioning and 0.30 for mental functioning, both indicating a fair degree of concordance. This disagreement differed in magnitude and direction depending on the level of disability present. We conclude that clinicians and their patients with RA often disagree in their assessment of the degree of physical and mental impairment that the patient experiences. These disagreements demonstrate the need for formal assessments of outcome and should be recognized and resolved when managing individual patients.

Adolescent↗
PubMed2002

The physical impact of computers and electronic game use on children and adolescents, a review of current literature.

Children using computers and electronic games may adopt the kinds of sustained and awkward postures that are associated with musculoskeletal disorders in working adults. If they do, the physical demands of extensive use could lead to a wide range of adverse effects on developing children, including visual, neurological and physical changes. This article reviews the literature related to media use, ergonomics, epidemiology and pediatrics that address the physical impact of computer use by children. The literature establishes that computer use is common, but does not demonstrate a causal or statistical association with any physical disorders. Laboratory studies on vision, case reports of game-related tendonitis and ergonomic analyses of classroom computers suggest that concern is warranted.

Adolescent↗
PubMed1987

Problems in estimating the prevalence of physical activity from national surveys.

Health policy in the United States has paid scant notice to physical activity until recently. This current policy focus on physical activity has revealed not only that there is less than adequate data about it but also that the single survey questions used for the purpose of measuring its prevalence should be interpreted carefully. A case in point is the example presented in this article, which gives estimates of physical activity prevalence levels for women of child-bearing ages from several National Center for Health Statistics (NCHS) surveys. The amount of physical activity reported, and thus the proportion of women at risk for various diseases due to limited activity, depends on how the question is asked and the type of responses offered as options. Various questions used in three different NCHS surveys produced prevalence estimates of limited physical activity levels ranging from 3.9 to 39.1%. These findings have important implications for survey assessments of physical activity at all policy levels.

Adult↗
PubMed2000

House dust mite control measures for asthma.

BACKGROUND: The major allergen in house dust comes from mites. Chemical, physical and combined methods of reducing mite allergen levels are intended to reduce asthma symptoms in people who are sensitive to house dust mites. OBJECTIVES: The objective of this review was to assess the effects of reducing exposure to house dust mite antigens in the homes of mite-sensitive asthmatics. SEARCH STRATEGY: We searched the Cochrane Airways Group trials register, checked reference lists of articles and hand-searched Respiration (1980 to 1996) and Clinical and Experimental Allergy (1980 to 1996). SELECTION CRITERIA: Randomised trials of mite control measures in asthmatic people known to be sensitive to house dust mites. DATA COLLECTION AND ANALYSIS: Two reviewers applied the trial inclusion criteria and extracted the data independently. One reviewer applied the trial quality assessment criteria. Study authors were contacted to clarify information. MAIN RESULTS: Twenty-three trials were included, with four trials awaiting assessment. There was little difference in improvement of asthma between people in experimental groups compared to control groups (odds ratio 1.2, 95% confidence interval 0.66 to 2.18). Asthma symptom scores were also similar for the experimental and control groups (standardised mean difference -0. 06, 95% confidence interval -0.54 to 0.41). These scores showed a high degree of heterogeneity. No significant difference was noted for medication usage (standardised mean difference -0.14, 95% confidence interval -0.43 to 0.15). Peak flow in the morning showed no significant difference between the experimental and the control groups (standardised mean difference -0.03, 95% confidence interval -0.25 to 0.19). REVIEWER'S CONCLUSIONS: Current chemical and physical methods aimed at reducing exposure to house dust mite allergens seem to be ineffective and cannot be recommended as prophylaxis for mite sensitive asthmatics.

Allergens↗
PubMed1987

Mixing one part common sense with each part statistics in planning the design and reporting the results of clinical research in physical therapy.

The purpose of this article is to discuss the importance of clinical research to improve the quality of clinical practice in physical therapy. Research is the process of posing an important, answerable question and collecting data to provide a convincing answer. Many of the manuscripts I reviewed for possible publication during the recent several years I was an Associate Editor contained one or more flaws that impaired the credibility of the study being reported. One of the flaws was inadequate identification of the research question and the measurements needed to collect the data that would answer the question; a second was insufficient rounding of the numbers used to convey the results; a third was misapplication of arithmetic operations to nominal or ordinal data; and another was the extrapolation of results from healthy young volunteers to explain why a particular treatment should or should not be effective in treating a pathological condition. I urge that physical therapy researchers learn to conduct indepth, thoughtfully guided studies to define the indicators that can be used to predict when a particular patient will respond favorably to a particular therapeutic intervention. Successful accomplishment of such studies will have a substantial and lasting impact on the efficacy and quality of physical therapy practice.

Humans↗
PubMed2005

Vocal impact on quality of life of elderly female subjects.

UNLABELLED: Although there are several investigations focusing the physiology and anatomy of voice and the senior's larynx, little has been produced to support the knowledge of the impact of vocal conditions on quality of life of this portion of the population. AIM: To verify the impact of voice on quality of the life of elderly women, using the questionnaires Short-Form Health Survey--SF36 and Voice Handicap Index (VHI). STUDY DESIGN: Prospective transversal cohort study. METHOD AND MATERIAL: Fifty senior women participated in this research, with ages between 60 and 87 years and mean age of 70.8 years old, randomly recruited. The participants of the study were submitted to two questionnaires: SF36 and VHI. The answers of both questionnaires were compared by Kruskall-Wallis test, verifying if there were significant differences among the variables. The test of Spearman was used to evaluate if there was correlation among the results of the variables of VHI and the results obtained in the parameter of SF36 for life quality. RESULTS: We obtained values considered statistically significant in the correlations among physical domain of VHI and physical operation, physical pain and physical role in life of SF36. CONCLUSION: There was a significant and positive correlation among the results obtained in the parameters physical operation, vitality, general health, mental health, corporal pain and physical role in life of SF36. There were statistically significant and negative correlations among the total results obtained in SF36 and VHI.

Aged↗
PubMed2005

Substrate concentration dependence of the diffusion-controlled steady-state rate constant.

The Smoluchowski approach to diffusion-controlled reactions is generalized to interacting substrate particles by including the osmotic pressure and hydrodynamic interactions of the nonideal particles in the Smoluchoswki equation within a local-density approximation. By solving the strictly linearized equation for the time-independent case with absorbing boundary conditions, we present an analytic expression for the diffusion-limited steady-state rate constant for small substrate concentrations in terms of an effective second virial coefficient B2*. Comparisons to Brownian dynamics simulations excluding hydrodynamic interactions show excellent agreement up to bulk number densities of B2*rho0 < approximately = 0.4 for hard sphere and repulsive Yukawa-like interactions between the substrates. Our study provides an alternative way to determine the second virial coefficient of interacting macromolecules experimentally by measuring their steady-state rate constant in diffusion-controlled reactions at low densities.

Anisotropy↗
PubMed2003

Estimates of echo correlation and measurement bias in acoustic radiation force impulse imaging.

Acoustic radiation force impulse (ARFI) imaging is a novel imaging modality in which pulses from a diagnostic ultrasound scanner are used to displace tissue and track its motion. The region displaced has lateral and elevational dimensions of similar scale to the ultrasound beams used to track the motion. Therefore, there is a range of tissue displacements present within the tracking beam, leading to decorrelation of the echo signal. Expressions are derived for the expected value of the displacement estimate and the cross-correlation at the expected displacement. Numerical simulations confirm the analytical model.

Computer Simulation↗
PubMed2006

[Prevalence of violence against women users of health services].

OBJECTIVE: Intimate partner abuse is a complex phenomenon and a public health problem and health care services are one of the places sought by women in this situation. The objective of this study was to assess the prevalence of violence against women attending a health care center. METHODS: This study was carried out in a municipality of Southeastern Brazil, in 2003. A sample of 265 women, aged 18 to 49 years old, was interviewed using a questionnaire administered face-to-face. Violence was classified as psychological, physical, sexual and general. Statistical analyses utilized were exact logistic regression and Fisher's exact test. RESULTS: Psychological violence, at least once in life, was reported by 41.5%, physical violence by 26.4%, and 9.8% reported sexual violence. "General violence", which refers to anyone of the above mentioned types of violence, was reported by 45.3% of the women, and, in 20.3% of the cases, they stated it had occurred during the last 12 months before the interview. However, when asked whether they had suffered any kind of violence in life, only 22.3% answered affirmatively. The multivariate analysis indicated that the risk factors for each type of violence were: drug use by the partner, socioeconomic status and family history of violence for both psychological and general violence; drug use by the partner, schooling and family history of violence for physical violence; and, socioeconomic status and family history of violence for sexual violence. CONCLUSIONS: This study indicates that the prevalence of violence among women attending the health center is high and consistent with the results of other investigations. It also suggests that most of the violence is invisible to the health center.

Adolescent↗
PubMed2006

What is a desirable statistical energy function for proteins and how can it be obtained?

Can one obtain a physical energy function for proteins from statistical analysis of protein structures? A direct answer to this question is likely "no." Aless demanding question is whether one can produce a statistical energy function that has the desirable features of a physical-based energy function. Such a desirable energy function would be founded on a physical basis with few or no adjustable parameters, reproduce the known physical characters of amino acid residues, be mostly database independent and transferable, and, more importantly, reasonably accurate in various applications. In this review, we show how such a desirable energy function can be obtained via introducing a simple physical-based reference state called DFIRE (Distance-scaled, Finite, Ideal-gas REference state).

Computer Simulation↗
PubMed2000

Physical functioning and health-related quality of life: before and after total hip replacement.

Total hip replacement (THR) is a commonly adopted procedure for arthritis-related diseases. Although the THR efficacy in pain relief and restoration of physical functioning has been extensively studied, it remains unclear how health-related quality of life is affected by THR. The major purpose of this study was to examine and compare the differences in physical functioning and health-related quality of life for THR patients before and after operations. Based on a prospective study design, 46 THR patients at one medical center were reviewed and followed up (six months after operations) during the period from March 1997 to June 1998, with a follow-up rate of 88%. The THR subjects were interviewed and measured by the Modified Harris Hip Scale and the Chinese-version Short-form 36-item Health Survey (SF-36). Patient characteristics and the information related to procedures were derived from chart review. The results indicated that the THR patients had statistically significant improvements in physical functioning and health-related quality of life. In terms of the Harris Score, the mean Harris score was 91.6 (SD = 10.7) 6 months after THR, as compared to 45.2 (SD = 17.3) before THR. The eight ratings in the SF-36 measures were also statistically significantly improved (p < 0.001). Specifically, "role limitations due to physical functioning" demonstrated dramatic improvements after THR (15.2 vs. 63.5), followed by "role limitations due to emotional problems" (25.4 vs. 85.5). The findings confirm the effectiveness of THR outcomes in terms of physical functioning, pain relief, and health-related quality of life, which can be revealed by disease-specific (Harris Scale) and generic health measures (SF-36).

Adult↗
PubMed2002

Average unit cell for Penrose tiling and its Gaussian approximation.

In this paper, the average unit cell for a quasicrystal is constructed by a statistical approach. For the Penrose tiling, it is shown that such a unit cell is fully equivalent to the oblique projection of the atomic surface onto physical space. The obtained statistical distributions can be easily extended to imperfect structures by using a Gaussian approximation. This leads to simple analytical expressions for diffraction intensities, which can be very useful in structure refinement.

Journal Article↗