PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “statistical physics”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

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

At least 1,243 records · Page 69Linked to original sources
PubMed2005

Pore-scale investigation of viscous coupling effects for two-phase flow in porous media.

Recent studies have revealed that viscous coupling effects in immiscible two-phase flow, caused by momentum transfer between the two fluid phases, can be important in porous medium systems. In this work, we use a three-dimensional parallel processing version of a two-fluid-phase lattice Boltzmann (LB) model to investigate this phenomenon. A multiple-relaxation-time (MRT) approximation of the LB equations is used in the simulator, which leads to a viscosity-independent velocity field. We validate our model by verifying the velocity profile for two-phase flow through a channel with a square cross section. We then simulate co-current flow through a sphere-pack porous medium and obtain correlations of the relative permeabilities as a function of capillary number, wettability, and the fluid viscosities. The results are qualitatively consistent with experimental observations. In addition, we calculate the generalized permeability coefficients and show that the coupling coefficients are significant and the matrix is nonsymmetric. We also find a strong correlation between the relative permeability and interfacial area between fluids, indicating that both the common extension of Darcy's Law and the generalized formulation accounting for viscous coupling effects do not provide adequate insight into two-phase flow processes in porous media. This work lends additional support for the hypothesis that interfacial area is a key variable for multiphase flow in porous medium systems.

Algorithms↗
PubMed1979

Sterilization: a comparative review.

Publications relating to surgical procedures for sterilization have been reviewed, and the incidences of complications and subsequent pregnancies compared. Laparoscopic sterilization has the lowest incidence of complication, the morbidity rate being lower than that of laparotomy sterilization or hysterectomy, and the mortality rate lower than that of a single pregnancy or taking oral contraceptives for 1 year.

Female↗
PubMed1988

Rating disabilities of older patients by nurses and social workers on geriatric health care teams: a research note with implications for further study.

This article reports the results of an analysis of interprofessional agreements between nurses and social workers when rating older patients on their physical self-maintenance abilities, mental statuses, and dispositions to social interaction with other residents of a home for the aged. The findings showed statistically significant intercorrelations of ratings of physical self-maintenance abilities and mental statuses, but no agreement on disposition to interaction. These findings are interpreted for their implications for research and practices of nurses and social-workers on geriatric health care teams.

Activities of Daily Living↗
PubMed2007

Knee-muscle activation during landings: developmental and gender comparisons.

PURPOSE: This study determined anteroposterior knee-joint muscle activation differences among children and adult males and females landing from a self-initiated vertical jump (VJ) under normal and offset-target conditions to further understand physical maturation's influence on anterior cruciate ligament (ACL) injury risk. METHODS: Fifty-five recreationally active volunteer subjects grouped by age (children = 9.5 +/- 0.9 yr; adult = 23.9 +/- 2.8 yr) and gender (females = 28; males = 27) completed motion analysis, ground reaction force, and surface electromyography (SEMG) data collection during a two-footed landing under straight (midline-target) and offset-target (adult = 45.7 cm; child = 30.5 cm) conditions. Target height was 50% of maximum VJ height. Co-contraction ratios (CCR) (hamstrings (HAMS)/vastus medialis (VM) activity) from normalized SEMG root mean squares were analyzed in the prelanding (PRE) (100 ms before initial contact (IC)), reflexive (REF) (100 ms after IC), and voluntary (VOL) (end of REF to maximum knee flexion) muscle activity phases. Repeated-measures statistical analyses determined significant gender, physical maturation, and target differences (P < 0.05) in CCR and associated HAMS and VM activity across landing phases. RESULTS: A significant interaction (P < 0.0001) indicated similar CCR for children and adults during the REF and VOL phases, but during the PRE phase adult CCR (619.04 + 52.01) were two times greater than children's (308.32 +/- 51.04). Significantly more HAMS activity, not less VM activity, increased adult PRE-CCR. Gender and target CCR differences were absent. CONCLUSIONS: Children's decreased preparatory co-contraction about the knee does not seem to be linked to increased ACL injury risk. Thus, adults may strive for preparatory co-contraction levels about the knee that permit adaptability to varied landing tasks.

Adolescent↗
PubMed1981

Systemic factors in patients with low-tension glaucoma.

Nineteen patients (38 eyes) with low-tension glaucoma were compared with 53 subjects (106 eyes) with ocular hypertension. Comparable for age and sex, the 2 groups were assessed with respect to haematological and biochemical criteria, physical activity, and medical history. Statistical analyses of the differences between the 2 groups highlighted the importance of diastolic ophthalmodynamometry levels, prediagnosis exercise habits, cardiovascular disease status, and possibly systolic blood pressure. Patients with low-tension glaucoma suffered a higher prevalence of multiple abnormalities of these systemic factors than did their ocular hypertensive counterparts. There were no significant differences between the 2 groups with respect to the many other factors examined.

Adult↗
PubMed1998

[Diagnostic significance of topical image of infrared thermograph on the patient with lumbar intervertebral disc herniation--a comparative study on 45 patients and 65 normal control].

OBJECTIVE: To analyse and explore the diagnostic significance of infrared thermography on the patients with lumbar intervertebral disc protrusion. METHODS: Forty-five hospitalized cases under conservative treatment (mainly manipulation) and 65 controls were sequentially selected. Both groups were examined with infrared thermograph on lower back and lower extremities as well as physical examination before and after treatment. The study statistically analysed the temperature difference between the involved and healthy parts at different areas; and also compared the change of the temperature difference after the treatment to the decreasing scores of physical examination afterward. RESULTS: The statistic result showed that the temperature difference between two sides on patients group was significantly higher than those of control group. The further analysis shows that the temperature difference at posterior femur area in the patient's group correlated significantly to the severity of clinical signs caused by nerve root irritation. CONCLUSIONS: The thermograph could only be considered as a reference in the diagnosis of lumbar disc protrusion. It is helpful to discover the severity of radical signs according to the posterior femoral region of hypo- (or hyper) thermogram.

Adult↗
PubMed2026

The Impact of Baseline Negative Emotions on Postoperative Quality of Life in Adolescent Idiopathic Scoliosis Patients: A 2-Year Follow-Up Study.

OBJECTIVE: Adolescent idiopathic scoliosis (AIS) is a three-dimensional spinal deformity that develops during puberty without a clear etiology. Beyond physical manifestations, AIS severely impacts adolescents' psychological and social well-being, leading to anxiety, depression, and low self-esteem. While advancements in surgical techniques have enhanced objective outcomes, existing studies on AIS have primarily focused on objective indices, with limited attention to the long-term impact of preoperative negative emotions on patient-reported subjective quality of life. METHODS: This was a retrospective cohort study. A total of 112 eligible AIS patients who underwent posterior spinal correction surgery between April and August 2023 were enrolled. Inclusion criteria included confirmed AIS, completion of 2-year follow-up, and informed consent; exclusion criteria included missing imaging/questionnaire data, comorbid psychiatric/neurological diseases, or prior spinal surgery. Patients were grouped using the Hospital Anxiety and Depression Scale (HADS) administered on admission. Quality of life was assessed preoperatively and 2&#x2009;years postoperatively using the Scoliosis Research Society-22 (SRS-22, evaluating self-image, mental health, pain, function, treatment satisfaction) and Short Form 36 Health Survey (SF-36, assessing 8 physical and mental health dimensions). Statistical analysis was performed via SPSS, using independent t-tests, paired t-tests, Mann-Whitney U test, and chi-square test. p&#x2009;<&#x2009;0.05 was considered significant. RESULTS: There were no significant differences in baseline characteristics (age, gender, BMI, surgical parameters, scoliosis type, preoperative/postoperative Cobb angles) between the two groups (all p&#x2009;>&#x2009;0.05). Preoperatively, SRS-22 and SF-36 scores showed no inter-group differences (all p&#x2009;>&#x2009;0.05). Postoperatively, the Negative Emotion Group had significantly lower scores in SRS-22 mental health (3.9&#x2009;&#xb1;&#x2009;0.3 vs. 4.5&#x2009;&#xb1;&#x2009;0.2) and treatment satisfaction (4.0&#x2009;&#xb1;&#x2009;0.3 vs. 4.6&#x2009;&#xb1;&#x2009;0.7), as well as SF-36 general health (68.6&#x2009;&#xb1;&#x2009;6.4 vs. 79.7&#x2009;&#xb1;&#x2009;13.3), role-emotional (61.3&#x2009;&#xb1;&#x2009;9.3 vs. 70.8&#x2009;&#xb1;&#x2009;9.7), and mental health (61.8&#x2009;&#xb1;&#x2009;14.3 vs. 68.9&#x2009;&#xb1;&#x2009;10.7) (all p&#x2009;<&#x2009;0.05); no inter-group differences were observed in physical function-related dimensions. Both groups showed significant improvements in physical function-related dimensions postoperatively. The Non-Negative Emotion Group also exhibited significant improvements in SRS-22 self-image/pain and SF-36 bodily pain (all p&#x2009;<&#x2009;0.05), while the Negative Emotion Group showed no significant improvements in these dimensions. CONCLUSIONS: Preoperative anxiety and depression do not affect the recovery of physical function in AIS patients after spinal correction surgery but significantly impede improvements in subjective quality of life dimensions, including mental health and treatment satisfaction. These findings highlight the need to integrate psychological assessment and targeted interventions into the perioperative management of AIS. Such a patient-centered approach will help optimize both physical and psychological outcomes, ultimately achieving comprehensive rehabilitation for AIS adolescents.

Humans↗
PubMed1995

Stratification of palpable and nonpalpable breast cancer by method of detection and age.

BACKGROUND: Methods used to diagnose breast cancer in women under the age of 50 years are somewhat controversial. To determine the relationship between type and stage of breast cancer, clinical presentation, and age, we reviewed breast cancer diagnosed at our institution during a recent 3-year period. METHODS: Records from 589 consecutive excisional biopsies and 372 needle placement biopsies performed over a 3-year period were reviewed. Carcinomas were staged according to the TNM system and results compared using chi 2. RESULTS: Breast carcinoma was diagnosed in 118 women during the study period, 33% in patients under 50 years of age. Breast cancer diagnosed by mammography in all age groups was more likely to be noninvasive than that diagnosed by physical examination (p < 0.05). The few invasive cancers diagnosed by mammography in women under age 50 were lower in stage than those diagnosed by physical examination, although not by a statistically significant amount (p = 0.125). Breast cancer diagnosed by mammography in women 50 years and older was significantly lower in stage than that diagnosed by physical examination (p < 0.05). CONCLUSIONS: Invasive carcinoma detected as a nonpalpable lesion by mammography was earlier in stage than invasive carcinoma detected by physical examination, including in women under 50 years of age, although the number of invasive cancers detected in younger women was quite small. The role of mammography in this younger age group remains to be defined.

Age Factors↗
PubMed2002

Quality of life of palliative care patients in the last two weeks of life.

Quality of life (QOL) is the main consideration in caring for advanced cancer patients, yet little is known about the QOL in the terminal phase. We profiled the QOL of 58 advanced cancer patients during their last 2 weeks of life using the McGill QOL questionnaire-Hong Kong version. The patients provided ratings of QOL an average of 5.6 (median 6) days pre-death. Palliative care services were successful in maintaining the total QOL score during the dying phase. The mean score was 7.0 of 10. Among the various domains, the physical and existential domains scored relatively poorly at 5.9 and 6 of 10, respectively. The worst physical symptom and meaning of life were the individual items with the poorest scores (4.8 and 5.4 of 10, respectively). Compared with admission, there was statistically significant improvement in the worst physical symptom (P = 0.02) and eating item (P = 0.002), but deterioration in physical well-being (P = 0.03), meaning of existence (P = 0.007), and satisfaction with oneself (P = 0.04). In conclusion, QOL evaluation during the terminal phase identifies important aspects requiring improvement during the last two weeks of life. Physical and existential domains of dying cancer patients needed more attention.

Humans↗
PubMed2002

Physical performance tasks: what are the underlying constructs?

OBJECTIVES: To investigate the structural validity of a battery of physical performance tasks and to investigate the construct validity of the resulting factors. DESIGN: A measurement study. SETTING: A large, private orthopedic clinic and a physical therapy clinic in an urban area. PARTICIPANTS: One hundred three consecutive adult patients with low back pain who were referred for physical therapy assessment. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: The physical performance battery was composed of the 50-foot speed walk, 5-minute walk, repeated trunk flexion, sit to stand, loaded reach, rollover tasks, and Sorensen upper-body lift. Participants also completed 5 self-report measures. RESULTS: Two correlated (.74) factors, speed and coordination and endurance and strength, were derived from the physical performance tasks. The Sorenson upper-body lift task was the only indicator that was not useful in defining the factors. Both factors had statistically significant correlations with measures of physical disability, lack of self-efficacy, and negative affect. Both factors had a trivial correlation with a numeric rating of pain intensity. CONCLUSIONS: There is support for 2 meaningful empiric groupings (ie, the derived factors) of the performance tasks. Pain intensity had a trivial overlap with speed-coordination and endurance-strength factors.

Adult↗
PubMed2004

A longitudinal analysis of efficacy expectations and exercise in older adults.

The purpose of this study was to consider the longitudinal changes in self-efficacy and outcome expectations for exercise and the impact of these variables on maintaining regular exercise over a 4-year period in a group of older adults living in a continuing care retirement community. There were 78 individuals who completed all four surveys. The participants had at least a high school education, and the majority were Caucasian (99%), female (83%) and either widowed or never married (80%). The mean age of the participants was 84.4+/-5.1 years. Based on repeated measure analysis of covariance, controlling for mental and physical health, there was not a statistically significant difference in self-efficacy expectations (F = 2.0, p > .05) or outcome expectations (F = 2.2, p > .05) over time. There was a statistically significant decrease in exercise over time (F = 9.9, p < .05). Using path analysis it was demonstrated that self-efficacy expectations, outcome expectations, and physical health directly and indirectly influenced maintenance of regular exercise. Age, gender, and mental health had a limited and inconsistent influence on maintenance of exercise. Future research and clinical work should focus on developing and testing interventions that strengthen both self-efficacy and positive outcome expectations in older adults to facilitate maintenance of exercise behavior over time.

Aged↗
PubMed2005

Promoting behavior change among working-class, multiethnic workers: results of the healthy directions--small business study.

OBJECTIVES: We examined the efficacy of a cancer prevention intervention designed to improve health behaviors among working-class, multiethnic populations employed in small manufacturing businesses. METHODS: Worksites were randomly assigned to an intervention or minimal-intervention control condition. The intervention targeted fruit and vegetable consumption, red meat consumption, multivitamin use, and physical activity. RESULTS: Employees in the intervention group showed greater improvements for every outcome compared with employees in the control group. Differences in improvement were statistically significant for multivitamin use and physical activity. Intervention effects were larger among workers than among managers for fruit and vegetable consumption and for physical activity. CONCLUSIONS: The social-context model holds promise for reducing disparities in health behaviors. Further research is needed to improve the effectiveness of the intervention.

Adult↗
PubMed2005

Representativeness of an automobile shredder residue sample for a verification analysis.

To apply a decision-making scheme using a statistical classification while conforming to the meaning of representativeness as defined by the US EPA, we propose an equation defining the representativeness of a sample. To utilize this equation, the batch must be homogenized. This requires analyzing the constitution and distribution heterogeneities. The equation relates the sample weight m(s) to its representativeness R either by a statistical approach or by a physical approach using the following equation: m(s) = {4/(1 - R)(2)}.[K + k(e)(1 - 2t(e))/t(e)]. In the equation, K and k(e) are the heterogeneity factors determined from a descriptive analysis. This equation is applicable to solid waste with majority constituents such as automobile shredder residue (ASR) and domestic waste. This analysis was applied to a sample of ASR in the framework of a verification for France. The results of the analysis showed that the sample weight must be at least 140 kg to have a representativeness of 90%.

Automobiles↗
PubMed1994

Neck strain in car occupants: injury status after 6 months and crash-related factors.

In this study, 29 individuals who sustained a neck strain as a result of a car crash were drawn from a group of physiotherapy and general practices and were followed up after 6 months. The aim was to examine relationships between the state of the neck injury at the time of follow up and crash-related factors, notably crash severity and occupant awareness. Crash severity was assessed by measurement of damage to the involved vehicles, while 6-month injury status was established through physical examinations and interviews. No statistically significant associations between crash severity and 6-month injury status were found, but subjects who were unaware of the impending collision had a greatly increased likelihood of experiencing persisting symptoms of and/or signs of neck strain, compared with those who were aware (odds ratio = 15.0; 95 per cent confidence limits: 1.8, 178). While the role of crash severity in the production and duration of neck strains remains unclear, awareness appears to have a strong protective influence and may prove to be a useful prognostic indicator in clinical settings.

Accidents, Traffic↗
PubMed2000

Lower beta-cell secretion in physically active first-degree relatives of type 2 diabetes patients.

Regular physical activity may prevent or postpone type 2 diabetes, and is thought to be related to an increase of insulin sensitivity. We studied whether physically active, glucose-tolerant first-degree relatives of type 2 diabetes patients differ in glucose tolerance (oral glucose tolerance test [OGTT]) and insulin secretion (hyperglycemic glucose clamp) from less active first-degree relatives. A group of 37 relatives was split into 2 subgroups according to the sex-specific median of the sports index, assessed by a questionnaire, as the cutoff point. Blood glucose levels during the OGTT were lower in the highly active subgroup versus the less active counterparts (multivariate ANOVA [MANOVA], P = .011), but the plasma insulin levels were similar. First-phase secretion was not different in the highly active group versus the less active group, but second-phase secretion (average plasma insulin in the third hour) was significantly lower (P = .016). As expected, the insulin sensitivity index (ISI) was higher in the highly active subgroup (P= .011). Subdivision into subgroups with high or low maximal O2 consumption (VO2max) resulted in similar differences, but these were not significant. In a group of 21 controls, the results resembled the values in the relatives but were less often statistically significant. In conclusion, regular physical activity not only is associated with increased insulin sensitivity but also downregulates the pancreatic beta cell. This downregulation may provide an extra mechanism by which physical activity diminishes the development of type 2 diabetes.

Adult↗
PubMed2003

Physical activity and breast cancer risk among Asian-American women in Los Angeles: a case-control study.

BACKGROUND: To the authors' knowledge, there have been few studies published to date regarding physical activity patterns and breast cancer risk in Asian and Asian-American women. METHODS: The authors conducted a population-based case-control study of 501 Asian-American women with incident breast cancer and a control group of 594 Asian-American women in Los Angeles County to evaluate the role of lifetime physical activity on breast cancer risk. Information concerning lifetime recreational physical activity (i.e., type of activity, duration [years], and frequency [average hours per week]) and occupational physical activity was obtained using a structured questionnaire that was administered in person. RESULTS: Increasing years and levels (average metabolic equivalent [MET] hours per week) of lifetime recreational activity were associated with a significantly reduced risk of breast cancer after adjusting for demographic factors, migration history, and menstrual and reproductive factors. Compared with women who had no lifetime recreational physical activity, 3-6 MET hours per week, > 6-12 MET hours per week, and > 12 MET hours per week of activity were associated with significantly reduced risk, with odds ratios (and 95% confidence intervals) of 0.91 (0.55-1.49), 0.65 (0.39-1.10), 0.53 (0.31-0.90), and 0.47 (0.28-0.80), respectively (P value for trend < 0.001). The risk of breast cancer was associated inversely with occupational physical activity, although the result was not statistically significant. CONCLUSIONS: The findings of the current study provide further support for the finding that physical activity has a protective role in breast cancer.

Adult↗