Stress dependent thermal pressurization of a fluid-saturated rock

Temperature increase in saturated porous materials under undrained conditions leads to thermal pressurization of the pore fluid due to the discrepancy between the thermal expansion coefficients of the pore fluid and of the solid matrix. This increase in the pore fluid pressure induces a reduction of the effective mean stress and can lead to shear failure or hydraulic fracturing. The equations governing the phenomenon of thermal pressurization are presented and this phenomenon is studied experimentally for a saturated granular rock in an undrained heating test under constant isotropic stress. Careful analysis of the effect of mechanical and thermal deformation of the drainage and pressure measurement system is performed and a correction of the measured pore pressure is introduced. The test results are modelled using a non-linear thermo-poro-elastic constitutive model of the granular rock with emphasis on the stress-dependent character of the rock compressibility. The effects of stress and temperature on thermal pressurization observed in the tests are correctly reproduced by the model

The effectiveness of physical activity monitoring and distance counselling in an occupational health setting - a research protocol for a randomised controlled trial (CoAct)

<p>Abstract</p> <p>Background</p> <p>The CoAct (Cocreating Activity) study is investigating a novel lifestyle intervention, aimed at the working population, with daily activity monitoring and distance counselling via telephone and secure web messages. The main purpose of this study is to evaluate the effectiveness of lifestyle counselling on the level of physical activity in an occupational health setting. The purposes include also analysing the potential effects of changes in physical activity on productivity at work and sickness absence, and healthcare costs. This article describes the design of the study and the participant flow until and including randomization.</p> <p>Methods/Design</p> <p>CoAct is a randomised controlled trial with two arms: a control group and intervention group with daily activity monitoring and distance counselling. The intervention focuses on lifestyle modification and takes 12 months. The study population consists of volunteers from 1100 eligible employees of a Finnish insurance company. The primary outcomes of this study are change in physical activity measured in MET minutes per week, work productivity and sickness absence, and healthcare utilisation. Secondary outcomes include various physiological measures. Cost-effectiveness analysis will also be performed. The outcomes will be measured by questionnaires at baseline, after 6, 12, and 24 months, and sickness absence will be obtained from the employer's registers.</p> <p>Discussion</p> <p>No trials are yet available that have evaluated the effectiveness of daily physical activity monitoring and distance counselling in an occupational health setting over a 12 month period and no data on cost-effectiveness of such intervention are available.</p> <p>Trial Registration</p> <p>ClinicalTrials.gov identifier: NCT00994565</p

Evaluation of lifestyle interventions to treat elevated cardiometabolic risk in primary care (E-LITE): a randomized controlled trial

<p>Abstract</p> <p>Background</p> <p>Efficacy research has shown that intensive individual lifestyle intervention lowers the risk for developing type 2 diabetes mellitus and the metabolic syndrome. Translational research is needed to test real-world models of lifestyle interventions in primary care settings.</p> <p>Design</p> <p>E-LITE is a three-arm randomized controlled clinical trial aimed at testing the feasibility and potential effectiveness of two lifestyle interventions: information technology-assisted self-management, either alone or in combination with care management by a dietitian and exercise counselor, in comparison to usual care. Overweight or obese adults with pre-diabetes and/or metabolic syndrome (n = 240) recruited from a community-based primary care clinic are randomly assigned to one of three treatment conditions. Treatment will last 15 months and involves a three-month intensive treatment phase followed by a 12-month maintenance phase. Follow-up assessment occurs at three, six, and 15 months. The primary outcome is change in body mass index. The target sample size will provide 80% power for detecting a net difference of half a standard deviation in body mass index at 15 months between either of the self-management or care management interventions and usual care at a two-sided α level of 0.05, assuming up to a 20% rate of loss to 15-month follow-up.</p> <p>Secondary outcomes include glycemic control, additional cardiovascular risk factors, and health-related quality of life. Potential mediators (e.g., treatment adherence, caloric intake, physical activity level) and moderators (e.g., age, gender, race/ethnicity, baseline mental status) of the intervention's effect on weight change also will be examined.</p> <p>Discussion</p> <p>This study will provide objective evidence on the extent of reductions in body mass index and related cardiometabolic risk factors from two lifestyle intervention programs of varying intensity that could be implemented as part of routine health care.</p> <p>Trial registration</p> <p>NCT00842426</p

Incidences of obesity and extreme obesity among US adults: findings from the 2009 Behavioral Risk Factor Surveillance System

<p>Abstract</p> <p>Background</p> <p>No recent national studies have provided incidence data for obesity, nor have they examined the association between incidence and selected risk factors. The purpose of this study is to examine the incidence of obesity (body mass index [BMI] ≥ 30.0 kg/m²) and extreme obesity (BMI ≥ 40.0 kg/m²) among US adults and to determine variations across socio-demographic characteristics and behavioral factors.</p> <p>Methods</p> <p>We used a weighted sample of 401,587 US adults from the 2009 Behavioral Risk Factor Surveillance System. Incidence calculations were based on respondent's height and current and previous weights. Logistic regression was used to examine associations between incidence and selected socio-demographic characteristics and behavioral factors.</p> <p>Results</p> <p>The overall crude incidences of obesity and extreme obesity in 2009 were 4% and 0.7% per year, respectively. In our multivariable analyses that controlled for baseline body mass index, the incidences of obesity and extreme obesity decreased significantly with increasing levels of education. Incidences were significantly higher among young adults, women, and adults who did not participate in any leisure-time physical activity. Incidence was lowest among non-Hispanic whites.</p> <p>Conclusions</p> <p>The high incidence of obesity underscores the importance of implementing effective policy and environmental strategies in the general population. Given the significant variations in incidence within the subgroups, public health officials should prioritize younger adults, women, minorities, and adults with lower education as the targets for these efforts.</p

The STRATOB study: design of a randomized controlled clinical trial of Cognitive Behavioral Therapy and Brief Strategic Therapy with telecare in patients with obesity and binge-eating disorder referred to residential nutritional rehabilitation

bstract BACKGROUND: Overweight and obesity are linked with binge eating disorder (BED). Effective interventions to significantly reduce weight, maintain weight loss and manage associated pathologies like BED are typically combined treatment options (dietetic, nutritional, physical, behavioral, cognitive-behavioral, pharmacological, surgical). Significant difficulties with regard to availability, costs, treatment adherence and long-term efficacy are present. Particularly Cognitive Behavioral Therapy (CBT) is the therapeutic approach indicated both in in-patient and in out-patient settings for BED. In recent years systemic and systemic-strategic psychotherapies have been implemented to treat patients with obesity and BED involved in familiar problems. Particularly a brief protocol for the systemic-strategic treatment of BED, using overall the strategic dialogue, has been recently developed. Moreover telemedicine, a new promising low cost method, has been used for obesity with BED in out-patient settings in order to avoid relapse after the in-patient step of treatment and to keep on a continuity of care with the involvement of the same clinical in-patient team. METHODS: The comparison between CBT and Brief Strategic Therapy (BST) will be assessed in a two-arm randomized controlled clinical trial. Due to the novelty of the application of BST in BED treatment (no other RCTs including BST have been carried out), a pilot study will be carried out before conducting a large scale randomized controlled clinical trial (RCT). Both CBT and BST group will follow an in-hospital treatment (diet, physical activity, dietitian counseling, 8 psychological sessions) plus 8 out-patient telephone-based sessions of psychological support and monitoring with the same in-patient psychotherapists. Primary outcome measure of the randomized trial will be the change in the Global Index of the Outcome Questionnaire (OQ-45.2). Secondary outcome measures will be the percentage of BED patients remitted considering the number of weekly binge episodes and the weight loss. Data will be collected at baseline, at discharge from the hospital (c.a. 1 month after) and after 6-12-24 months from the end of the in-hospital treatment. Data at follow-up time points will be collected through tele-sessions. DISCUSSION: The STRATOB (Systemic and STRATegic psychotherapy for OBesity), a comprehensive two-phase stepped down program enhanced by telepsychology for the medium-term treatment of obese people with BED seeking intervention for weight loss, will shed light about the comparison of the effectiveness of the BST with the gold standard CBT and about the continuity of care at home using a low-level of telecare (mobile phones). TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT0109625

Pore Volume and Porosity Changes under Uniaxial Strain Conditions

Expressions for the changes that occur in the pore volume and the porosity of a porous rock, due to changes in the pore pressure, overburden stress, and temperature, are derived within the context of the linearised theory of poroelasticity. The resulting expressions are compared to the commonly used equations proposed by Palmer and Mansoori, and it is shown that their expressions are consistent with the exact expressions if their factor f is identified with (1+ν)/3(1−ν)(1+ν)/3(1−ν) , where νν is the Poisson’s ratio of the porous rock. Finally, the first derivation is given, within the context of the fully coupled linearised theory of poroelasticity, that under uniaxial strain, the partial differential equation that governs the evolution of the pore pressure is a pure diffusion equation, with a total compressibility term that (exactly) equals the sum of the fluid compressibility and the uniaxial pore volume compressibility