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PubMed2003

Equilibrium free energies from nonequilibrium measurements using maximum-likelihood methods.

We present a maximum likelihood argument for the Bennett acceptance ratio method, and derive a simple formula for the variance of free energy estimates generated using this method. This derivation of the acceptance ratio method, using a form of logistic regression, a common statistical technique, allows us to shed additional light on the underlying physical and statistical properties of the method. For example, we demonstrate that the acceptance ratio method yields the lowest variance for any estimator of the free energy which is unbiased in the limit of large numbers of measurements.

Journal Article↗
PubMed2006

Physical activity and strength of the femoral neck during the adolescent growth spurt: a longitudinal analysis.

Loading of the femoral neck (FN) is dominated by bending and compressive stresses. We hypothesize that adaptation of the FN to physical activity would be manifested in the cross-sectional area (CSA) and section modulus (Z) of bone, indices of axial and bending strength, respectively. We investigated the influence of physical activity on bone strength during adolescence using 7 years of longitudinal data from 109 boys and 121 girls from the Saskatchewan Paediatric Bone and Mineral Accrual Study (PBMAS). Physical activity data (PAC-Q physical activity inventory) and anthropometric measurements were taken every 6 months and DXA bone scans were measured annually (Hologic QDR2000, array mode). We applied hip structural analysis to derive strength and geometric indices of the femoral neck using DXA scans. To control for maturation, we determined a biological maturity age defined as years from age at peak height velocity (APHV). To account for the repeated measures within individual nature of longitudinal data, multilevel random effects regression analyses were used to analyze the data. When biological maturity age and body size (height and weight) were controlled, in both boys and girls, physical activity was a significant positive independent predictor of CSA and Z of the narrow region of the femoral neck (P < 0.05). There was no independent effect of physical activity on the subperiosteal width of the femoral neck. When leg length and leg lean mass were introduced into the random effects models to control for size and muscle mass of the leg (instead of height and weight), all significant effects of physical activity disappeared. Even among adolescents engaged in normal levels of physical activity, the statistically significant relationship between physical activity and indices of bone strength demonstrate that modifiable lifestyle factors like exercise play an important role in optimizing bone strength during the growing years. Physical activity differences were explained by the interdependence between activity and lean mass considerations. Physical activity is important for optimal development of bone strength.

Adolescent↗
PubMed1996

On the consistency of a physical mapping method to reconstruct a chromosome in vitro.

During recent years considerable effort has been invested in creating physical maps for a variety of organisms as part of the Human Genome Project and in creating various methods for physical mapping. The statistical consistency of a physical mapping method to reconstruct a chromosome, however, has not been investigated. In this paper, we first establish that a model of physical mapping by binary fingerprinting of DNA fragments is identifiable using the key assumption-for a large randomly generated recombinant DNA library, there exists a staircase of DNA fragments across the chromosomal region of interest. Then we briefly introduce epi-convergence theory of variational analysis and transform the physical mapping problem into a constrained stochastic optimization problem. By doing so, we prove epi-convergence of the physical mapping model and epi-convergence of the physical mapping method. Combining the identifiability of our physical mapping model and the epi-convergence of a physical mapping method, finally we establish strong consistency of a physical mapping method.

Aspergillus nidulans↗
PubMedDate not supplied

The value of pseudoneurological symptoms for assessing psychopathology in primary care.

OBJECTIVE: This study sought to examine the relationship between pseudoneurological symptoms (PNS) and somatic and psychiatric symptom severity, physical functioning, and psychiatric comorbidity. METHODS: Interview and questionnaire data were obtained from 120 patients with somatization who participated in a study assessing the efficacy of cognitive-behavioral therapy. Measures elicited information on psychiatric diagnoses, anxiety and depressive symptom levels, somatic symptoms, and physical functioning. Statistical analyses examined the relationship between PNS and the diagnosis of somatization disorder, physical and psychiatric symptom severity, and psychiatric comorbidity. RESULTS: Roughly half of the sample had a history of four or more PNS. Results showed that having four or more PNS was not predictive of somatization disorder. However, having four or more PNS was found to be significantly correlated with the severity of anxiety, depression, somatic complaints, and physical dysfunction. These associations were identified while controlling for the symptom count of nonpseudoneurological symptoms, the presence of somatization disorder, and the presence of chronic painful physical conditions. In addition, having four or more PNS was significantly associated with a higher likelihood of receiving a diagnosis of major depression, dysthymia, panic disorder, and generalized anxiety disorder. CONCLUSIONS: A history of four or more PNS is common among somatizing patients in primary care and associated with a more severe clinical presentation, even after controlling for other factors known to be associated with severity. Four or more PNS may identify a distinct subgroup of somatization and serve as a clinical indicator for identifying psychiatric disorders in primary care. Future studies should explore the assessment of PNS using briefer measures. Furthermore, PNS should be evaluated with samples more representative of US primary care populations, as well as samples that include adequate representation from other ethnic backgrounds (eg, African-American, Asian, etc.).

Adolescent↗
PubMed1978

Multidisciplinary treatment of chronic pain: long-term follow-up of low-back pain patients.

Thirty-six patients with low-back pain who had been treated in our multidisciplinary pain center returned for 80-week follow-up evaluations by the staff pscyhologist, physiatrist and physical therapist. Statistically significant gains were maintained in the reduction of prescription analgesics and on 4 measures of physical functioning: (a) long-sittimg-to-toe; (b) straight-leg-raise; (c) knee-to-chest; and (d) overall exercise performance. Despite verbal reports of continuing pain, most patients claimed they were coping much better with it, and they displayed a marked reduction in their utilization of medical resources for further pain treatment. These long-term results suggest that a multidisciplinary approach can offer an effective means of treating chronic low-back pain.

Adaptation, Psychological↗
PubMed2006

Iterative reconstruction techniques in emission computed tomography.

In emission tomography statistically based iterative methods can improve image quality relative to analytic image reconstruction through more accurate physical and statistical modelling of high-energy photon production and detection processes. Continued exponential improvements in computing power, coupled with the development of fast algorithms, have made routine use of iterative techniques practical, resulting in their increasing popularity in both clinical and research environments. Here we review recent progress in developing statistically based iterative techniques for emission computed tomography. We describe the different formulations of the emission image reconstruction problem and their properties. We then describe the numerical algorithms that are used for optimizing these functions and illustrate their behaviour using small scale simulations.

Algorithms↗
PubMed1995

Visual training programme applied to precision shooting.

A three month visual training programme was conducted at the CAR of Sant Cugat (Olympic Training Center). Eleven members of 'The Catalan Government Special Intervention Squad' were used in a clinical trial. Pre-test and post-test results were obtained for pistol shooting, visual function, and psychological and physical states. Statistical analysis indicated significant gains in visual function and pistol shooting scores after the programme, while psychological (anxiety) and physical condition remained the same. Some conclusive statements can be made with regard to the relation of visual function improvement and shooting performance increment, after analysing the data. This improvement is evident in statistically significant post-test gains in the following variables: 'phoria at distance, recovery points in fusional reserves at distance, analytical amplitude, negative relative accommodation, saccadic fixations, and accommodative facility at distance and at near. The rest of the controlled visual variables also showed clinical improvement.

Accommodation, Ocular↗
PubMed2005

Survivors of acute respiratory distress syndrome: relationship between pulmonary dysfunction and long-term health-related quality of life.

BACKGROUND: Patients who survive acute respiratory distress syndrome (ARDS) often report decreased general health-related quality of life (HRQOL) following hospital discharge. The extent to which this impairment is due to pulmonary or nonpulmonary causes is unclear. We describe the pattern of recovery of patients surviving ARDS to illuminate any relationships between lung spirometry values, pulmonary symptoms, and overall HRQOL. METHODS: Seventy-three survivors of ARDS were enrolled in a 12-month follow-up study as part of a phase III randomized, multicenter trial. Patients were contacted at 3, 6, and 12 months after enrollment to complete generic and disease-specific HRQOL questionnaires and have lung spirometry tests performed. RESULTS: For all domains of the Medical Outcomes Study Short Form-36 (SF-36) and the St. George's Respiratory Questionnaire (SGRQ) at all time intervals, survivors of ARDS had significantly lower scores than age- and sex-matched population values. Over the 12-month follow-up period, we observed significant improvements to the overall Physical Component Score, but the Mental Component Score of the SF-36 and the SGRQ scores were not statistically different. Physical performance measures suggested that by 12 months, 57% had not returned to "normal activity." At 12 months, lung spirometry tests demonstrated mild abnormalities that were stable over time (64% and 49% had <80% predicted forced expiratory volume in 1 sec [Fev1] and forced vital capacity [Fvc], respectively). At 12 months, the forced expiratory volume in 1 sec correlated strongly with the physical function domain of the SF-36 (correlation coefficient = 0.601; p < .01) and moderately with all domains of the SGRQ (correlation coefficient = -0.36, -50; p < .01 in all cases). In addition, there were several strong to moderate correlations between the various domains of the SF-36 and SGRQ. CONCLUSIONS: Survivors of ARDS have considerable respiratory symptoms and reduced HRQOL that is still prevalent at 12 mos following onset of injury. There are significant correlations between lung spirometry, pulmonary symptoms, and overall HRQOL, thus suggesting the acute lung injury/ARDS is causally contributing to the observed long-term outcome.

Adolescent↗
PubMed2006

Effect of nurse-led gut-directed hypnotherapy upon health-related quality of life in patients with irritable bowel syndrome.

AIMS AND OBJECTIVES: This study quantified health-related quality of life in a group of irritable bowel syndrome patients and measures changes following a treatment programme of nurse-led gut-directed hypnotherapy. BACKGROUND: It is well recognized that health-related quality of life can be severely impaired in patients suffering form the irritable bowel syndrome. Current conventional treatment for irritable bowel syndrome is often unsatisfactory. In contrast it has been shown that gut-directed hypnotherapy is an effective treatment of irritable bowel syndrome with up to three-quarters of patients reporting symptomatic improvement. DESIGN/METHOD: Seventy-five patients (55 females/20 males, median age 37.1 years, age range 18-64) comprised the study group. Physical symptoms of irritable bowel syndrome were recorded using seven-day diary cards. On presentation the predominant symptoms were abdominal pain (61%), altered bowel habit (32.5%), and abdominal distension/bloating (6.5%) in the patient group. An irritable bowel syndrome quality of life questionnaire was used to define health-related quality of life. Psychological well-being was measured using the Hospital Anxiety and Depression Scale. Data analysis was carried out using MINITAB, Release 12 for Windows. RESULTS: Physical symptoms statistically improved after hypnotherapy. There were also significant statistical improvements (P < 0.001) in six of the eight health-related quality of life domains measured (emotional, mental health, sleep, physical function, energy and social role). These improvements were most marked in female patients who reported abdominal pain as their predominant physical symptom. Anxiety and depression improved following treatment. CONCLUSION: Gut-directed hypnotherapy has a very positive impact on health-related quality of life with improvements in psychological well-being and physical symptoms. It appears most effective in patients with abdominal pain and distension. Relevance to clinical practice. This study demonstrates that by integrating complementary therapies into conventional care that gastrointestinal nurses have a potential role in the management of irritable bowel syndrome.

Humans↗