Conception et réalisation des capteurs hybrides photovoltaïque-thermiques sous vide ou avec lame d’air confinée

Cette étude fait l’analyse des performances thermiques et électriques de deux types de capteurs solaires hybrides photovoltaïque-thermiques à air intégrables en toitures des bâtiments. Pour ces capteurs hybrides, les cellules PV sont isolées soit avec une lame d’air confinée ou soit avec un gap vide. La modélisation des transferts de chaleur dans les systèmes est effectuée en 2D et en régime transitoire, suivant l’approche nodale. Le code numérique développé a été validé et a permis d’analyser les comportements thermiques ainsi que les efficacités thermique et électrique des capteurs. L’optimisation des paramètres fonctionnels est ensuite effectuée et présentée.Mots-clés: énergie solaire, cellules photovoltaïques, capteurs solaires hybrides (PV/T), transferts thermiques. Conception and realization of hybrid photovoltaic thermal collectors with empty gap or with enclosed air cavityThe present work reports thermal and electrical efficiencies for two solar hybrid photovoltaic-thermal air collectors integrated into the roof of the buildings. In these hybrid collectors, the PV cells are insulated with the enclosed air film or with the empty gap cavity. The unsteady and two-dimensional heat transfer equations are proposed and these equations are discretized using nodal method. The numerical model developed is validated. Then thermal and electrical efficiencies are analyzed for the collectors. The optimization of the characteristics parameters is studied in detail.Keywords: solar energy, photovoltaic cells, hybrid solar collector, heat transfer, nodal method

High-Dose Chemotherapy Followed by Autologous Stem Cell Transplantation for Metastatic Rhabdomyosarcoma—A Systematic Review

INTRODUCTION: Patients with metastatic rhabdomyosarcoma (RMS) have a poor prognosis. The aim of this systematic review is to investigate whether high-dose chemotherapy (HDCT) followed by autologous hematopoietic stem cell transplantation (HSCT) in patients with metastatic RMS has additional benefit or harm compared to standard chemotherapy. METHODS: Systematic literature searches were performed in MEDLINE, EMBASE, and The Cochrane Library. All databases were searched from inception to February 2010. PubMed was searched in June 2010 for a last update. In addition to randomized and non-randomized controlled trials, case series and case reports were included to complement results from scant data. The primary outcome was overall survival. A meta-analysis was performed using the hazard ratio as primary effect measure, which was estimated from Cox proportional hazard models or from summary statistics of Kaplan Meier product-limit estimations. RESULTS: A total of 40 studies with 287 transplant patients with metastatic RMS (age range 0 to 32 years) were included in the assessment. We identified 3 non-randomized controlled trials. The 3-year overall survival ranged from 22% to 53% in the transplant groups vs. 18% to 55% in the control groups. Meta-analysis on overall survival in controlled trials showed no difference between treatments. Result of meta-analysis of pooled individual survival data of case series and case reports, and results from uncontrolled studies with aggregate data were in the range of those from controlled data. The risk of bias was high in all studies due to methodological flaws. CONCLUSIONS: HDCT followed by autologous HSCT in patients with RMS remains an experimental treatment. At present, it does not appear justifiable to use this treatment except in appropriately designed controlled trials

Design and methods for evaluating an early childhood obesity prevention program in the childcare center setting

BACKGROUND: Many unhealthy dietary and physical activity habits that foster the development of obesity are established by the age of five. Presently, approximately 70 percent of children in the United States are currently enrolled in early childcare facilities, making this an ideal setting to implement and evaluate childhood obesity prevention efforts. We describe here the methods for conducting an obesity prevention randomized trial in the child care setting. METHODS/DESIGN: A randomized, controlled obesity prevention trial is currently being conducted over a three year period (2010-present). The sample consists of 28 low-income, ethnically diverse child care centers with 1105 children (sample is 60% Hispanic, 15% Haitian, 12% Black, 2% non-Hispanic White and 71% of caregivers were born outside of the US). The purpose is to test the efficacy of a parent and teacher role-modeling intervention on children’s nutrition and physical activity behaviors. . The Healthy Caregivers-Healthy Children (HC2) intervention arm schools received a combination of (1) implementing a daily curricula for teachers/parents (the nutritional gatekeepers); (2) implementing a daily curricula for children; (3) technical assistance with meal and snack menu modifications such as including more fresh and less canned produce; and (4) creation of a center policy for dietary requirements for meals and snacks, physical activity and screen time. Control arm schools received an attention control safety curriculum. Major outcome measures include pre-post changes in child body mass index percentile and z score, fruit and vegetable and other nutritious food intake, amount of physical activity, and parental nutrition and physical activity knowledge, attitudes, and beliefs, defined by intentions and behaviors. All measures were administered at the beginning and end of the school year for year one and year two of the study for a total of 4 longitudinal time points for assessment. DISCUSSION: Although few attempts have been made to prevent obesity during the first years of life, this period may represent the best opportunity for obesity prevention. Findings from this investigation will inform both the fields of childhood obesity prevention and early childhood research about the effects of an obesity prevention program housed in the childcare setting. TRIAL REGISTRATION: Trial registration number: NCT0172203