520 research outputs found
Motion and performance analysis of an experimental model floating wind turbine
Laboratory measurements of the motion and rotor performance of a model floating wind turbine
were undertaken under simple wind and wave conditions. The model consisted of a 40cm diameter
rotor mounted on a fully submerged cylinder supported vertically by four arms to form a tension leg
floater. The laboratory facility involved a low-wind speed straight-through wind tunnel assembled
on the water wave generator. The turbine was connected to a DC generator and an electrical
variable-resistance load to vary the rotor speed. Tests were undertaken for one fixed wind speed,
varying the rotor tip speed ratio and wave conditions. Four different one-dimensional wave
conditions were considered, each with a different wavelength and frequency. Sensors were
installed to measure the unsteady wave height and surge of the turbine platform. Other sensors
were installed to measure the rotor speed and the generator output power.
The measurements show the effects of rotor tip speed ratio and wave condition on the surge
motion of the floater. The presence of aerodynamic damping due to the turbine was evident for
certain wave conditions. The rotor experienced considerable deviations in the power coefficient
characteristics when subjected to waves. The deviations were larger at and above the optimal tip
speed ratio.
Good agreement was obtained when the measurements for the power coefficient and surge
displacement were compared with those from a simplified mathematical model. The model was
based on the Blade-Element Momentum theory for rotor aerodynamics and on the Morison
equation for the hydrodynamic forces on the floater.peer-reviewe
ANGPTL4 variants E40K and T266M are associated with lower fasting triglyceride levels in Non-Hispanic White Americans from the Look AHEAD Clinical Trial
Background: Elevated triglyceride levels are a risk factor for cardiovascular disease. Angiopoietin-like protein 4 (Angptl4) is a metabolic factor that raises plasma triglyceride levels by inhibiting lipoprotein lipase (LPL). In nondiabetic individuals, the ANGPTL4 coding variant E40K has been associated with lower plasma triglyceride levels while the T266M variant has been associated with more modest effects on triglyceride metabolism. The objective of this study was to determine whether ANGPTL4 E40K and T266M are associated with triglyceride levels in the setting of obesity and T2D, and whether modification of triglyceride levels by these genetic variants is altered by a lifestyle intervention designed to treat T2D. Methods: The association of ANGPTL4 E40K and T266M with fasting triglyceride levels was investigated in 2,601 participants from the Look AHEAD Clinical Trial, all of whom had T2D and were at least overweight. Further, we tested for an interaction between genotype and treatment effects on triglyceride levels. Results: Among non-Hispanic White Look AHEAD participants, ANGPTL4 K40 carriers had mean triglyceride levels of 1.61 +/- 0.62 mmol/L, 0.33 mmol/L lower than E40 homozygotes (p = 0.001). Individuals homozygous for the minor M266 allele (MAF 30%) had triglyceride levels of 1.75 +/- 0.58 mmol/L, 0.24 mmol/L lower than T266 homozygotes (p = 0.002). The association of the M266 with triglycerides remained significant even after removing K40 carriers from the analysis (p = 0.002). There was no interaction between the weight loss intervention and genotype on triglyceride levels. Conclusions: This is the first study to demonstrate that the ANGPTL4 E40K and T266M variants are associated with lower triglyceride levels in the setting of T2D. In addition, our findings demonstrate that ANGPTL4 genotype status does not alter triglyceride response to a lifestyle intervention in the Look AHEAD study
Lifestyle interventions for weight loss in adults with severe obesity: a systematic review
Severe obesity is an increasingly prevalent condition and is often associated with long-term comorbidities, reduced survival and higher healthcare costs. Non-surgical methods avoid the side effects, complications and costs of surgery, but it is unclear which non-surgical method is most effective. The objective of this article was to systematically review the effectiveness of lifestyle interventions compared to standard or minimal care for weight loss in adults with severe obesity. MEDLINE, EMBASE, CENTRAL, databases of on-going studies, reference lists of any relevant systematic reviews and the Cochrane Library database were searched from inception to February 2016 for relevant randomized controlled trials (RCTs). Inclusion criteria were participants with severe obesity (body mass index [BMI] > 40 kg/m(2) or BMI > 35 kg/m(2) with comorbidity) and interventions with a minimal duration of 12 weeks that were multi-component combinations of diet, exercise and behavioural therapy. Risk of bias was evaluated using the Cochrane risk of bias criteria. Meta-analysis was not possible because of methodological heterogeneity. Seventeen RCTs met the inclusion criteria. Weight change in kilograms of participants from baseline to follow-up was reported for 14 studies. Participants receiving the lifestyle intervention had a greater decrease in weight than participants in the control group for all studies (1.0-11.5 kg). Lifestyle interventions varied greatly between the studies. Overall lifestyle interventions with combined diet and exercise components achieved the greatest weight loss. Lifestyle interventions for weight loss in adults with severe obesity were found to result in increased weight loss when compared to minimal or standard care, especially those with combined diet and exercise components
Influence of the Duration of Diabetes on the Outcome of a Diabetes Self-Management Education Program
BackgroundDiabetes education and lifestyle modification are critical components in controlling blood glucose levels of people with type 2 diabetes. Until now, available data on the effectiveness of education with respect to the duration of diabetes are limited. We investigated whether adherence to lifestyle behavior modification prompted by diabetes education was influenced by the duration of diabetes.MethodsTwo hundred and twenty-five people with type 2 diabetes were recruited for an intensive, collaborative, group-based diabetes education program with annual reinforcement. We divided the patients into two groups based on the duration of their diabetes prior to the education program (≤1 year [≤1Y] vs. ≥3 years [≥3Y]). Dietary habits, physical activity, and the frequency of blood glucose self-monitoring were evaluated with a questionnaire prior to education and at the follow-up endpoint.ResultsThe mean follow-up period was 32.2 months. The mean hemoglobin A1c (A1C) value was significantly lower in the ≤1Y group. Self-care behaviors, measured by scores for dietary habits (P=0.004) and physical activity (P<0.001), were higher at the endpoint in the ≤1Y group than in the ≥3Y group. Logistic regression analysis revealed that a longer diabetes duration before education was significantly associated with mean A1C levels greater than or equal to 7.0% (53 mmol/mol).ConclusionDiabetes duration influenced the effectiveness of diabetes education on lifestyle behavior modification and glycemic control. More-intense, regular, and sustained reinforcement with encouragement may be required for individuals with longstanding type 2 diabetes
Early Identification of Type 2 Diabetes: Policy should be aligned with health systems strengthening
This article does not have an abstract
The Association of Unintentional Changes in Weight, Body Composition, and Homeostasis Model Assessment Index with Glycemic Progression in Non-Diabetic Healthy Subjects
BackgroundWe performed a retrospective longitudinal study on the effects of changes in weight, body composition, and homeostasis model assessment (HOMA) indices on glycemic progression in subjects without diabetes during a four-year follow-up period in a community cohort without intentional intervention.MethodsFrom 28,440 non-diabetic subjects who participated in a medical check-up program in 2004, data on anthropometric and metabolic parameters were obtained after four years in 2008. Body composition analyses were performed with a bioelectrical impedance analyzer. Skeletal muscle index (SMI, %) was calculated with lean mass/weight×100. Subjects were divided into three groups according to weight change status in four years: weight loss (≤-5.0%), stable weight (-5.0 to 5.0%), weight gain (≥5.0%). Progressors were defined as the subjects who progressed to impaired fasting glucose or diabetes.ResultsProgressors showed worse baseline metabolic profiles compared with non-progressors. In logistic regression analyses, the increase in changes of HOMA-insulin resistance (HOMA-IR) in four years presented higher odds ratios for glycemic progression compared with other changes during that period. Among the components of body composition, a change in waist-hip ratio was the strongest predictor, and SMI change in four years was a significant negative predictor for glycemic progression. Changes in HOMA β-cell function in four years was a negative predictor for glycemic progression.ConclusionIncreased interval changes in HOMA-IR, weight gain and waist-hip ratio was associated with glycemic progression during a four-year period without intentional intervention in non-diabetic Korean subjects
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