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Search Results: 1 - 10 of 463293 matches for " Gérard Roizès "
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Molecular and evolutionary characteristics of the fraction of human alpha satellite DNA associated with CENP-A at the centromeres of chromosomes 1, 5, 19, and 21
Nathalie Pironon, Jacques Puechberty, Gérard Roizès
BMC Genomics , 2010, DOI: 10.1186/1471-2164-11-195
Abstract: In this paper, we show that the molecular mechanisms by which these arrays evolve are identical in multiple chromosomes: i) accumulation of crossovers that homogenise and expand the arrays into different domains and subdomains that are mostly unshared between homologues and ii) sporadic mutations and conversion events that simultaneously differentiate them from one another. Individual arrays are affected by these mechanisms to different extents that presumably increase with time. Repeats associated with CENP-A, where the centromere is formed, are subjected to the same evolutionary mechanisms, but constitute minor subsets that exhibit subtle sequence differences from those of the bulk repeats. While the DNA sequence per se is not essential for centromere localisation along an array, it appears that certain sequences can be selected against. On chromosomes 1 and 19, which are more affected by the above evolutionary mechanisms than are chromosomes 21 and 5, CENP-A associated repeats were also recovered from a second homogeneous array present on each chromosome. This could be a way for chromosomes to sustain mitosis and meiosis when the normal centromere locus is ineluctably undermined by the above mechanisms.We discuss, in light of these observations, possible scenarios for the normal evolutionary fates of human centromeric regions.Although human alpha satellite DNA sequences have been studied for decades, a number of their structural and evolutionary characteristics remain obscure. It is generally accepted that sequences constituting highly homogeneous arrays, including those within which the active centromere is formed, evolve in a concerted way [1]. In view of this concerted evolution, many authors have supposed that the repeats are homogenised with high efficiency, both intra-chromosomally and between homologues. At the same time, it has been shown that meiotic recombination is highly suppressed in the centromeric chromosomal regions [2-5]. Indeed, it was recently
La sonification de l'environnement : ic nes sonores de Windows
Gérard Chandès
Revue Fran?aise des Sciences de l’Information et de la Communication , 2012,
Abstract: L'étude met l'accent sur la spécificité de la réalité sonore non musicale et les questions qu'elle pose en termes d'intersubjectivité sémantique. Elle présente un rapide panorama des travaux actuels. Dans le cadre général de la relation homme-machine, elle s'intéresse aux ic nes sonores des systèmes d'exploitation Windows XP 2000 et Vista, sur le mode de l'analyse sémiopragmatique de discours. Elle cherche à décrire des morphologies, à les associer à des fonctions, à discerner les imaginaires sous-jacents aux morphologies. Elle cherche à déterminer la logique et le sens des évolutions entre XP 2000 et Vista. The study focuses on the specific reality of non-musical sound reality and the questions it raises in terms of semantic intersubjectivity. It presents a brief overview of current work. Within the framework of the man-machine relationship, it is interested in sound icons of Windows operating systems XP 2000 and Vista, on the mode of the semiopragmatic analysis of discourse. It seeks to describe morphologies, to associate them functions, to discern the underlying imaginary morphologies. It seeks to determine the logic and meaning of the changes between XP 2000 and Vista.
In Vivo Evaluation of the Skin Tensile Strength by the Suction Method: Pilot Study Coping with Hysteresis and Creep Extension
Gérald E. Piérard,Sébastien Piérard,Philippe Delvenne,Claudine Piérard-Franchimont
ISRN Dermatology , 2013, DOI: 10.1155/2013/841217
Abstract: From an engineering standpoint, both the skin and subcutaneous tissue act as interconnected load-transmitting structures. They are subject to a variety of intrinsic and environmental influences. Changes in the cutaneous viscoelasticity represent an important aspect in a series of skin conditions. The aim of this work was to explore the methodology of biomechanical measurements in order to better appreciate the evolution and severity of some connective tissue diseases. The Cutometer MPA 580 (C+K electronic) was used in the steep and progressive suction procedures. Adapting measurement modalities was explored in order to mitigate any variability in data collection. The repeat steep suction procedure conveniently reveals the creep phenomenon. By contrast, the progressive suction procedure highlights the hysteresis phenomenon. These viscoelastic characteristics are presently described using the 2 and 4?mm probes on normal skin and in scleroderma, acromegaly, corticosteroid-induced dermatoporosis, and Ehlers-Danlos syndrome. The apposition of an additional outer contention on the skin altered differently the manifestations of the creep extension and hysteresis among the tested skin conditions. Any change in the mechanical test procedure affects the data. In clinical and experimental settings, it is mandatory to adhere to a strict and controlled protocol. 1. Introduction Measurements of a number of physical parameters characterizing human skin have been attempted over the recent decades. A diversity of devices assessing skin viscoelasticity were used both in vitro and in vivo [1, 2]. They proved to be useful tools for scientists and medical practitioners [3, 4]. Over a large part of the body, the overall viscoelastic behaviour of the skin primarily depends on the skin connective tissue (SCT) structures present in both the dermis and the subcutis, with minimal contribution from the epidermis [5–7]. The suction method is one of the most widely used approach for determining some of the biomechanical characteristics of human skin in health and disease [8–17]. The progressive suction mode with a stress-versus-strain graphic recording is a convenient way in this endeavour [9–11]. In this procedure, a progressive increase in stress suction for a defined period of time is followed by a symmetrical rate of suction release. During the whole process, skin deformation defined as the strain is recorded. Typically, viscoelastic materials exhibit nonlinear stress-versus-strain properties [1, 2, 9, 17]. The hysteresis loop represents the area delimited by the two curves
Un système régional de télécommunications spatiales: Arabsat
Gérard GAU,Isabelle SOURBèS
Mappemonde , 1989,
Abstract: Concurrentes au moins partiellement du système Intelsat, les télécommunications spatiales régionales ne se sont développées que récemment. Le système Arabsat reflète la complexité des relations politiques, culturelles et économiques entre les états arabes.
Sada: ville ou village
Marie S. Bock,Yann Gérard
Mappemonde , 2001,
The Major Y-Chromosome Haplogroup R1b-M269 in West-Europe, Subdivided by the Three SNPs S21/U106, S145/L21 and S28/U152, Shows a Clear Pattern of Geographic Differentiation  [PDF]
Gérard Lucotte
Advances in Anthropology (AA) , 2015, DOI: 10.4236/aa.2015.51003
Abstract: More than 2600 unrelated males from West-Europe were analysed by molecular hybridization experiments for the p49a,fTaq I polymorphisms. A total of 895 subjects (34%), belonging to haplogroup M269, were identified and further analysed for the three SNPs, S21/U106, S145/L21 and S28/U152; these three SNPs define the Northwest, West and South European sub-haplogroups, respectively. These haplogroups showed quite different frequency distribution patterns within West-Europe, with frequency peaks in Northern Europe, in Brittany in France and in Northern Italy/Southern France.
Exploration of the Face of the Turin Shroud. Pollens Studied by SEM Analysis  [PDF]
Gérard Lucotte
Archaeological Discovery (AD) , 2015, DOI: 10.4236/ad.2015.34014
Abstract: We studied by SEM-EDX analysis the pollens on the Face of the Turin Shroud. A total of ten pollen grains were found; they were photographed, characterised and analysed. Three of them (pollens p6, p7 and p10) belong to Ceratonia siliqua, the carob tree; one of them (pollen p1) belongs to Balanites aegyptiaca (the palm tree of the desert), and another one (pollen p9) belongs to Cercis siliquastrum (the Judean tree). These three plants have their geographical distributions in the Near-East; that is indicative of a Palestinian origin of the Turin Shroud. Two pollen grains (p3 and p4) belong to Myosotis ramosissima. Probably myositis flowers were deposited later on the Turin Shroud, as reverence for this venerable and symbolic object.
Assessing Community-Level and Single-Species Models Predictions of Species Distributions and Assemblage Composition after 25 Years of Land Cover Change
Sébastien Bonthoux, Andrés Baselga, Gérard Balent
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0054179
Abstract: To predict the impact of environmental change on species distributions, it has been hypothesized that community-level models could give some benefits compared to species-level models. In this study we have assessed the performance of these two approaches. We surveyed 256 bird communities in an agricultural landscape in southwest France at the same locations in 1982 and 2007. We compared the ability of CQO (canonical quadratic ordination; a method of community-level GLM) and GLMs (generalized linear models) to i) explain species distributions in 1982 and ii) predict species distributions, community composition and species richness in 2007, after land cover change. Our results show that models accounting for shared patterns between species (CQO) slightly better explain the distribution of rare species than models that ignore them (GLMs). Conversely, the predictive performances were better for GLMs than for CQO. At the assemblage level, both CQO and GLMs overestimated species richness, compared with that actually observed in 2007, and projected community composition was only moderately similar to that observed in 2007. Species richness projections tended to be more accurate in sites where land cover change was more marked. In contrast, the composition projections tended to be less accurate in those sites. Both modelling approaches showed a similar but limited ability to predict species distribution and assemblage composition under conditions of land cover change. Our study supports the idea that our community-level model can improve understanding of rare species patterns but that species-level models can provide slightly more accurate predictions of species distributions. At the community level, the similar performance of both approaches for predicting patterns of assemblage variation suggests that species tend to respond individualistically or, alternatively, that our community model was unable to effectively account for the emergent community patterns.
Stroke Epidemiology in Douala: Three Years Prospective Study in a Teaching Hospital in Cameroon  [PDF]
Yacouba N. Mapoure, C. Kuate, Clet B. Tchaleu, Hugo B. Mbatchou Ngahane, Gérard N. Mounjouopou, Hamadou Ba, Salomon Mbahe, Julius Y. Fonsah, Gérard Beyiha, Henry N. Luma, Albert S. Mouelle, Philomène K. Ndouongo, Alfred K. Njamnshi
World Journal of Neuroscience (WJNS) , 2014, DOI: 10.4236/wjns.2014.45044
Abstract: Background and Objectives: Cerebro-vascular accident or stroke constitutes a major challenge in sub-Saharan Africa. In Cameroon, basic epidemiologic data are not routinely available. Aims: The aim of this study was to determine the type, the associated risk factors, time to admission, the clinical presentation and the case fatality of stroke at the Douala General Hospital (DGH) in Cameroon. Methods: A cross-sectional study was performed from January 1, 2010 to December 31, 2012 at the neurology and intensive care units of the DGH. All patients above 15 years of age with a diagnosis of established stroke were enrolled. For each patient, socio-demographic, clinical and paraclinical data were recorded as well as the duration of hospitalization and the case fatality. Results: In all, 325 patients were enrolled with males constituting 68.1% and general mean age of 58.66 ± 13.6 years. The mean initial consultation delay was 47.36 ± 18.48 hours. The majors cerebro-vascular risk factors were hypertension (81.15%), chronic alcohol consumption (28.3%), diabetes mellitus (20.61%), obesity (18.15%), cigarette smoking (16%), dyslipidemia (8.9%) and atrial fibrillation (3.07%). Ischemic stroke accounted for 52% of cases while 48% were hemorrhagic. The mean duration of hospitalization was 8.58 ± 6.35 days with a case fatality rate of 26.8%. Septic conditions appeared to be the leading cause of death accounting for 35.6% of cases. Conclusion: Stroke in the DGH is associated with a high case fatality rate and hypertension remains the number one risk factor. There is a clear and urgent need for public health authorities to reinforce measures for the control of modifiable stroke risk factors.
Risques de gel accru liés à la présence d’ouvrages linéaires en remblai
Hervé Quenol,Gérard Beltrando,Sébastien Bridier
EchoGéo , 2008,
Abstract: Sur un coteau, le remblai d’un ouvrage de transport, en créant un obstacle à l’écoulement naturel de l’air froid superficiel, favorise la formation d’un lac d’air froid. Au printemps, cet obstacle peut accro tre le risque de gel dommageable pour les cultures qui sont vulnérables à cet aléa (vigne, arbres fruitiers…). A partir de mesures météorologiques aux échelles fines, réalisées lors des nuits froides de type radiatives (vent faible et ciel clair) et en simulant le remblai sur une longueur conséquente par l’intermédiaire d’un bache, il est possible d’évaluer grossièrement le différentiel thermique que va constituer cet ouvrage. Une autre méthode, basée sur la simulation de l’ouvrage en remblai, dans un SIG, et d’une validation sur le terrain aboutit à des résultats proches. Les exemples présentés ici proviennent d’études réalisées ces dernières années sur les remblais des lignes à grande vitesse du TGV Est européen (dans le vignoble de Champagne) et du TGV Méditerranée (dans les terroirs arboricoles de la basse vallée de la Durance). Les résultats montrent des différences de températures de plusieurs degrés et aussi une stagnation plus longue de l’air froid superficiel en amont du remblai, ce qui peut provoquer la destruction des jeunes bourgeons. Devant l’importance des problèmes prévisibles, le Ma tre d’ouvrage a proposé des aménagements afin de réduire au mieux ce risque supplémentaire. By radiativ weather (weak wind and clear sky), an embankment located in below slope level generates an obstacle with the natural flow of the cold air and it develops the formation of cold air lake. In spring, this obstacle can increase the frost risk for the vulnerable cultures (vine, fruit trees...). Weather measurements on fine scales and embankment simulation (with a plastic cover or in a GIS) permit to evaluate the temperature difference after the embankment implantation. The examples presented here are the impact of the embankments of high speed lines of the East European TGV (in the Champagne vineyard) and of the Mediterranean TGV (in orchards of Durance Valley). The results show a temperature difference of several degrees and also a longer stagnation of cold air surface upstream of the embankment, which can cause the buds destruction. With the importance of the foreseeable problems, the building owner proposed installations in order to reduce this additional risk.
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