Hugues J.N.,University of Paris 13
Human Reproduction | Year: 2012
BACKGROUND: The influence of LH on serum progesterone rise during gonadotrophin stimulation is a matter of debate. The purpose of this analysis was to assess the impact of supplementation with 'LH activity' products on serum progesterone changes before hCG administration in GnRH analog-treated women. METHODS: A computerized literature search was performed to identify studies comparing FSH treatment alone to those that provided supplementation with 'LH activity' using hMG, recombinant (r)LH (rLH) or hCG in GnRH analog protocols. Data regarding stimulation regimens were extracted from those that reported serum progesterone levels at the time of hCG in order to assess the specific role of LH activity products. RESULTS: Serum progesterone determination at the time of hCG administration was performed in 34 out of 108 studies comparing the effects of FSH alone or in combination with LH activity products. In a vast majority, no significant difference in serum progesterone could be found between stimulation regimens. However, in four studies where LH activity (three hMG and one rLH) was administered from the beginning of ovarian stimulation, serum P-values were significantly decreased. In contrast, in two studies where LH activity (hCG) was provided during the late follicular phase, serum P-values were significantly increased. Analysis of confounding factors showed that the intensity of ovarian stimulation is the most important determining factor to explain serum progesterone elevation at the time of hCG administration, CONCLUSIONSThis systematic review shows that providing LH activity supplementation in combination with FSH during ovarian stimulation does not have a consistent effect on serum progesterone concentrations at the time of hCG administration. However, these data also suggest that, in accordance with physiological concept, the timing of LH activity administration could influence the impact on serum progesterone changes. © The Author 2011.
Darquie B.,University of Paris 13
Chirality | Year: 2010
Parity violation (PV) effects in chiral molecules have so far never been experimentally observed. To take up this challenge, a consortium of physicists, chemists, theoreticians, and spectroscopists has been established and aims at measuring PV energy differences between two enantiomers by using high-resolution laser spectroscopy. In this article, we present our common strategy to reach this goal, the progress accomplished in the diverse areas, and point out directions for future PV observations. The work of André Collet on bromochlorofluoromethane (1) enantiomers, their synthesis, and their chiral recognition by cryptophanes made feasible the first generation of experiments presented in this article. © 2010 Wiley-Liss, Inc.
Kesse-Guyot E.,University of Paris 13
American Journal of Epidemiology | Year: 2012
Findings regarding the association between n-3 polyunsaturated fatty acid (PUFA) status and depression are conflicting. Thus, the authors studied associations between PUFA intake and depressive symptoms. In 1996, depressive symptoms were assessed in a subsample of participants from the Supplementation with Antioxidant Vitamins and Minerals (SU.VI.MAX) Study using the Center for Epidemiologic Studies Depression Scale (CES-D). In 2007-2009, information on CES-D score, history of depression, and use of antidepressant medication was obtained. Intakes of n-3 PUFAs were estimated from repeated 24-hour dietary records collected during 1994-1996. Subjects with depressive symptoms (cases) were identified using CES-D scores greater than 15 and/or antidepressant use. Logistic regression analyses were used. Cross-sectional (n = 2,744) and longitudinal (n = 1,235) associations between quartiles of PUFA intake and depressive symptoms were estimated. In cross-sectional analyses, quartile of n-3 PUFA intake was associated with lower odds of depressive symptoms (fourth quartile vs. first: odds ratio = 0.74, 95% confidence interval: 0.58, 0.95; P for trend = 0.001). No association between PUFA intake and incidence of depressive symptoms over 13 years was detected. This study provides new insights into the PUFA-depression link. While no association between n-3 PUFA intake and incidence of depressive symptoms was detected, an association was observed in cross-sectional analyses, which may reflect unhealthy dietary patterns among subjects with depressive symptoms. © The Author 2012. Published by Oxford University Press on behalf of the Johns Hopkins Bloomberg School of Public Health. All rights reserved.
Li J.,University of Paris 13
International Journal of Solids and Structures | Year: 2011
In this paper, we first describe a homogenization methodology with the aim of establishing strain gradient constitutive relations for heterogeneous materials. The methodology presented in this work includes two main steps. The first one is the construction of the average strain-energy density for a well-chosen RVE by using a homogenization technique. The second one is the transformation of the obtained average strain-energy density to that for the continuum. An important characteristic of this method is its self-consistency with respect to the choice of the RVE: the strain gradient constitutive law built by using the present method is independent of the size and the form of the RVE. In the frame of this homogenization procedure, we have constructed a strain gradient constitutive relation for a two-dimensional elastic material with many microcracks by adopting the self-consistent scheme. It was shown that the effective behavior of cracked solids depends not only on the crack density but also on the average crack size with which the strain gradient is associated. The proposed constitutive relation provides a starting point for the development of an evolution law of damage including strain gradient effect, which will be presented in the second part of this work. © 2011 Elsevier Ltd. All rights reserved.
Znaidi L.,University of Paris 13
Materials Science and Engineering B: Solid-State Materials for Advanced Technology | Year: 2010
During the last years, ZnO thin films have been studied extensively due to their potential applications in e.g. piezoelectric and optoelectronic devices or photovoltaic cells. Ordered c-axis orientation of ZnO crystallites is desirable for applications where crystallographic anisotropy is a prerequisite such as for short-wavelength semiconductor diode lasers (SDLs), and piezoelectric surface acoustic wave or acousto-optic devices. Many works were dedicated to c-axis oriented ZnO thin films elaboration and the study of their properties, including physical and chemical methods. For instance, sol-gel processes are particularly well adapted to produce ZnO films in a simple, low-cost and highly controlled way. This review summarizes the main chemical routes used in the sol-gel synthesis of undoped ZnO thin films and highlights the chemical and physical parameters influencing their structural properties. In this process, the ZnO films synthesis includes three principal steps: (i) solution preparation, (ii) coating and (iii) heat treatment. For the first step, the particle formation is discussed including nucleation and growth, particle size, morphology and colloids stability. These three steps involve several parameters such as: (i) nature and concentration of precursor, solvent and additive, and solution aging time, for the chemical system, (ii) coating method, thickness and substrate for the coating step, and (iii) pre-and post-heat treatment for the last step. The influence of these steps and synthesis parameters on ZnO thin films orientation is discussed. © 2010 Elsevier B.V. All rights reserved.