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Search Results: 1 - 10 of 4025 matches for " Alain Sibille "
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Time-Domain Diversity in Ultra-Wideband MIMO Communications
Alain Sibille
EURASIP Journal on Advances in Signal Processing , 2005, DOI: 10.1155/asp.2005.316
Abstract: The development of ultra-wideband (UWB) communications is impeded by the drastic transmitted power limitations imposed by regulation authorities due to the ¢ € polluting ¢ € character of these radio emissions with respect to existing services. Technical solutions must be researched in order either to limit the level of spectral pollution by UWB devices or to increase their reception sensitivity. In the present work, we consider pulse-based modulations and investigate time-domain multiple-input multiple-output (MIMO) diversity as one such possible solution. The basic principles of time-domain diversity in the extreme (low multipath density) or intermediate (dense multipath) UWB regimes are addressed, which predict the possibility of a MIMO gain equal to the product Nt —Nr of the numbers of transmit/receive antenna elements when the channel is not too severe. This analysis is confirmed by simulations using a parametric empirical stochastic double-directional channel model. They confirm the potential interest of MIMO approaches solutions in order to bring a valuable performance gain in UWB communications.
Statistical Modeling of Antenna: Urban Equipment Interactions for LTE Access Points
Xin Zeng,Alain Sibille
International Journal of Antennas and Propagation , 2012, DOI: 10.1155/2012/292018
Abstract: The latest standards for wireless networks such as LTE are essentially based on small cells in order to achieve a large network capacity. This applies for antennas to be deployed at street level or even within buildings. However, antennas are commonly designed, simulated, and measured in ideal conditions, which is not the real situation for most applications where antennas are often deployed in proximity to objects acting as disturbers. In this paper, three conventional wireless access point scenarios (antenna-wall, antenna-shelter, and antenna lamppost) are investigated for directional or omnidirectional antennas. The paper first addresses the definition of three performance indicators for such scenarios and secondly uses such parameters towards the statistical analysis of the interactions between the wall and the antennas. 1. Introduction With the development of new wireless communication systems and standards, antennas of base stations or access points are more likely deployed at street level in proximity to walls and urban furniture other than the traditional antennas for GSM networks which are mounted on rooftops with few neighboring disturbers [1–3]. The effect of surrounding disturbers may be strong or weak and is very sensitive to the antenna location and antenna characteristics. Unfortunately, antennas are commonly designed, simulated, and measured in isolation from anything else as much as possible, which is not a realistic use case. For instance, the radiation pattern of a dipole mounted beside a wall is highly perturbed, indicating the severe performance degradation to omnidirectionality (see below). Unfortunately, such disturbances are highly variable and impact the behavior of antennas in an uneasily predictable manner, with significant consequences in terms of cell coverage. The latter can be quantitatively evaluated through, for example, ray tracing of even empirical propagation simulation tools, but it will be very costly to compute the propagation for many realizations of disturbed antenna characteristics. For this reason, a reasonable approach is first to develop a statistical model for the antenna radiation behavior, before combining it with a model of simulation of the propagation. It is the goal of this paper, keeping in mind that statistical models lend themselves to the tuning of the trade-off between complexity and accuracy, depending on the number of parameters involved in the statistical distributions. For instance, [4] gives an example of this approach through radiation patterns series expansions. Actually, the evaluation of
Single and Multiple Scattering in UWB Bicone Arrays
Raffaele D'Errico,Alain Sibille
International Journal of Antennas and Propagation , 2008, DOI: 10.1155/2008/129584
Abstract: An analysis of interactions between radiators in a UWB biconical array, drawing attention to single and multiple scatterings, is carried out. The complementarity between electrical coupling and radiation scattering is argued. The point source approximation is discussed and shown to be insufficient. An approximation of radiation scattering based on angular averaging of the scattering coefficient is proposed. This approach yields a reduction of the problem complexity, which is especially interesting in UWB multiple antenna systems, because of the large bandwidth. Multiple scattering between radiators is shown to be a second-order effect. Finally, a time domain approach is used in order to investigate pulse distortion and quantify the exactness of the proposed scattering model.
Le parler occitan de Chiomonte (Italie) : situation linguistique et sociolinguistique (au contact de l’italien, du fran ais, du piémontais et du francoproven al)
Sibille Jean
SHS Web of Conferences , 2012, DOI: 10.1051/shsconf/20120100233
Abstract: Le parler occitan de Chiomonte (Italie) : situation linguistique et sociolinguistique (au contact de l’italien, du fran ais, du piémontais et du francoproven al) La Haute Vallée de Suse (ou Vallée d’Oulx), du c té italien du col du Montgenèvre, ainsi que la vallée du Haut Cluson, étaient jadis partie intégrante du Dauphiné. Elles on été cédées par la France au Royaume de Piémont-Savoie lors du traité d’Utrecht en 1713. Elles sont devenues italiennes lors de l’unification de l’Italie en 1861. L’italien s’y est substitué au fran ais comme langue dominante (et officielle) au tournant du XIXe et du XXe siècle. Dans la Haute Vallée de Suse, le vernaculaire occitan est en contact avec deux autres langues vernaculaires : le franco-proven al parlée dans la moyenne vallée et le piémontais parlé à Suse et dans la basse vallée, près de Turin. Chiomonte est le dernier village occitanophone à la fois au nord et à l’est : à 3 km on parle francoproven al, à 7 km piémontais. Le parler de Chiomonte fait partie de l’ensemble dialectal occitan dénommé vivaro-alpin, mais de par sa situation il présente des affinités aréale avec des parlers situés hors de la zone occitane (piémontais et francoproven aux) et est influencé par un double superstrat : fran ais à date ancienne et italien pour la période plus récente. Il présente des caractéristiques communes avec la partie la plus septentrionale de la zone nord occitane. Les adultes autochtones de Chiomonte sont souvent trilingues, voire quadrilingues, mais on observe des différences entre les générations. La transmission familiale de l’occitan a cessé dans les années 1950-1970, et le parler occitan de Chiomonte, bien qu’il compte encore un nombre significatif de locuteurs – pas toujours très agés – est un idiome en grand danger. Le fait que, de ce c té-ci de la frontière le parler local ne soit pas dévalorisés dans les représentations collectives est de peu de poids face aux mutations économiques et sociales, et aux médias qui favorisent la généralisation de l’italien. Le piémontais, en expansion dans les années 1960-1970 est également en recul et la connaissance du fran ais a considérablement régressé chez les plus jeunes. C’est ainsi qu’en quatre générations, on est passé d’un quadrilinguisme quasi général, à un quasi monolinguisme italien.
Differentially Expressed Genes in Major Depression Reside on the Periphery of Resilient Gene Coexpression Networks
Chris Gaiteri,Etienne Sibille
Frontiers in Neuroscience , 2011, DOI: 10.3389/fnins.2011.00095
Abstract: The structure of gene coexpression networks reflects the activation and interaction of multiple cellular systems. Since the pathology of neuropsychiatric disorders is influenced by diverse cellular systems and pathways, we investigated gene coexpression networks in major depression, and searched for putative unifying themes in network connectivity across neuropsychiatric disorders. Specifically, based on the prevalence of the lethality–centrality relationship in disease-related networks, we hypothesized that network changes between control and major depression-related networks would be centered around coexpression hubs, and secondly, that differentially expressed (DE) genes would have a characteristic position and connectivity level in those networks. Mathematically, the first hypothesis tests the relationship of differential coexpression to network connectivity, while the second “hybrid” expression-and-network hypothesis tests the relationship of differential expression to network connectivity. To answer these questions about the potential interaction of coexpression network structure with differential expression, we utilized all available human post-mortem depression-related datasets appropriate for coexpression analysis, which spanned different microarray platforms, cohorts, and brain regions. Similar studies were also performed in an animal model of depression and in schizophrenia and bipolar disorder microarray datasets. We now provide results which consistently support (1) that genes assemble into small-world and scale-free networks in control subjects, (2) that this efficient network topology is largely resilient to changes in depressed subjects, and (3) that DE genes are positioned on the periphery of coexpression networks. Similar results were observed in a mouse model of depression, and in selected bipolar- and schizophrenia-related networks. Finally, we show that baseline expression variability contributes to the propensity of genes to be network hubs and/or to be DE in disease. In summary, our results suggest that the small-world and scale-free properties of gene networks are resilient to pathological changes in major depression, and that the network structure may constrain the extent to which a gene may be DE in the illness, hence informing further gene-network-based mechanistic studies of neuropsychiatric disorders.
Carnot Factor of a Vapour Power Cycle with Regenerative Extraction  [PDF]
Duparquet Alain
Journal of Modern Physics (JMP) , 2017, DOI: 10.4236/jmp.2017.811107
Abstract: The present paper describes the energy analysis of a regenerative vapour power system. The regenerative steam turbines based on the Rankine cycle and comprised of vapour extractions have been used industrially since the beginning of the 20th century, particularly regarding the processes of electrical production. After having performed worked in the first stages of the turbine, part of the vapour is directed toward a regenerative exchanger and heats feedwater coming from the condenser. This process is known as regeneration, and the heat exchanger where the heat is transferred from steam is called a regenerator (or a feedwater heater). The profit in the output brought by regenerative rakings is primarily enabled by the lack of exchange of the tapped vapour reheating water with the low-temperature reservoir. The economic optimum is often fixed at seven extractions. One knows the Carnot relation, which is the best possible theoretical yield of a dual-temperature cycle; in a Carnot cycle, one makes the assumption that both compressions and expansions are isentropic. This article studies an ideal theoretical machine comprised of vapour extractions in which each cycle partial of tapped vapour obeys these same compressions and isentropic expansions.
Essay on Playfulness and Play in Children’s Art Class: A Reflection Based on Winnicott  [PDF]
Alain Savoie
Creative Education (CE) , 2019, DOI: 10.4236/ce.2019.102024
Abstract: From a survey of literature, this article presents some reflections about the value of play and playfulness as, respectively, an activity and a creative attitude of mind to be fostered in art education in children. Indeed, at the heart of any artistic creative impulse sits a playful attitude of the artist towards realitya feature that has been highlighted by the psychoanalyst Winnicott. Following his line of thought, we propose that the art teacher must place the learner in a position of being able to play with her/him, in order to overlap their two areas of playing and establish a learning space. Playfulness and play tend to be confused with impulsive and disruptive behaviours and generally more tolerated at home then school. We claim that artistic activities in school should always be play-based and take place in a playful environment because art and creation emerge from and grow in and as play.
Design of a Performance Measurement Framework for Cloud Computing  [PDF]
Luis Bautista, Alain Abran, Alain April
Journal of Software Engineering and Applications (JSEA) , 2012, DOI: 10.4236/jsea.2012.52011
Abstract: Cloud Computing is an emerging technology for processing and storing very large amounts of data. Sometimes anomalies and defects affect part of the cloud infrastructure, resulting in a performance degradation of the cloud. This paper proposes a performance measurement framework for Cloud Computing systems, which integrates software quality concepts from ISO 25010.
A human-mouse conserved sex bias in amygdala gene expression related to circadian clock and energy metabolism
Li-Chun Lin, David A Lewis, Etienne Sibille
Molecular Brain , 2011, DOI: 10.1186/1756-6606-4-18
Abstract: Using gene arrays followed by quantitative PCR validation, we compared the transcriptome profiles between sexes in human and mouse amygdala. We now report sexually dimorphic features of transcriptomes in the basolateral nucleus of the amygdala, and these features are highly conserved across species. A functional analysis of differential gene expression showed that mitochondrial-related gene groups were identified as the top biological pathways associated with sexual dimorphism in both species.These results suggest that the basolateral amygdala is a sexually dimorphic structure, featuring a regulatory cascade of mitochondrial function and circadian rhythm, potentially linked through sirtuins and hormone nuclear receptors. Hence, baseline differences in amygdalar circadian regulation of cellular metabolism may contribute to sex-related differences in mood regulation and vulnerability to major depression.Males and females differ in behavior and brain structure, as well as in prevalence of neuropsychiatric disorders. The greater prevalence of major depression and rapid cycling bipolar disorder in women [1,2] highlights the importance of studying potential mechanisms for sex differences. Sex chromosome- and hormone-linked genes may directly affect sexually dimorphic neurobiology [3]. For example, sex hormones regulate the size of the medial amygdala and bed nucleus of the stria terminalis during development [4]. The lateral (LA) and basal (basolateral; throughout the article we refer to human BA and mouse BLA) nuclei of the amygdala have been identified as critical sites for learned fear and emotion regulation in healthy subjects and in patients with mood disorders [5,6], but little is known about their sexual dimorphism. The isolation of subnuclei from the amygdala complex improves microarray sensitivity to detect differences in gene expression by reducing sample heterogeneity, and could facilitate the subsequent identification of genetic sex differences. To characteriz
LPS induces IL-10 production by human alveolar macrophages via MAPKinases- and Sp1-dependent mechanisms
Hugues Chanteux, Amélie C Guisset, Charles Pilette, Yves Sibille
Respiratory Research , 2007, DOI: 10.1186/1465-9921-8-71
Abstract: The present study investigated the role of intracellular signalling and transcription factors controlling the production of IL-10 in LPS-activated HAM from normal nonsmoking volunteers.LPS (1–1000 pg/ml) induced in vitro IL-10 production by HAM, both at mRNA and protein levels. LPS also activated the phosphorylation of ERK, p38 and JNK MAPkinases (immunoblots) and Sp-1 nuclear activity (EMSA). Selective inhibitors of MAPKinases (respectively PD98059, SB203580 and SP600125) and of Sp-1 signaling (mithramycin) decreased IL-10 expression in HAM. In addition, whilst not affecting IL-10 mRNA degradation, the three MAPKinase inhibitors completely abolished Sp-1 activation by LPS in HAM.These results demonstrate for the first time that expression of IL-10 in lung macrophages stimulated by LPS depends on the concomitant activation of ERK, p38 and JNK MAPKinases, which control downstream signalling to Sp-1 transcription factor. This study further points to Sp-1 as a key signalling pathway for IL-10 expression in the lung.Strategically located on the alveolar surface, alveolar macrophages represent highly specialized macrophages that function primarily in lung defence against inhaled particle matter, microorganisms and environmental toxins. Among microorganisms, gram-negative bacteria and more precisely, the lipopolysaccharide (LPS) component of the outer cell wall, is a very potent activator of macrophages. LPS binds to LPS-binding protein and is delivered to the cell surface receptor CD14, before being transferred to the transmembrane signaling receptor toll-like receptor 4 (TLR4) and its accessory protein MD2 [1]. LPS stimulation activates several intracellular signaling pathways including the three mitogen-activated protein kinase (MAPK) pathways: extracellular signal-regulated kinases (ERK) 1 and 2, c-Jun N-terminal kinase (JNK) and p38. These signalling pathways in turn activate a variety of transcription factors which coordinate the induction of many genes encoding inf
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