194 research outputs found
Evolution des sols irrigués dans la moyenne vallée du fleuve Sénégal : sodisation/alcalinisation
The Architecture Competition: A Beauty Contest or a Learning Opportunity?
The architecture competition is a high point of interaction between very diverse actors, architecture specialists or not. However, is it really an opportunity for exchange and shared learning? Based on surveys conducted in France and in several European countries on behalf of the French Ministry of Culture, this contribution aims to identify the conditions that foster the interactions inherent to competitions, the possible scope of these exchanges and the rationale behind them. When the competition is a chosen procedure, it is most often perceived as a moment of generating ideas that opens a professional debate and also addresses the general public. When it is mandatory, the competition is guided by another logic: that of ensuring the fairness and transparency of the joint choice of a project and a service provider as well as the legality of the contract concluded with the latter. Depending on the place given by decision-makers to this legal and contractual dimension, the nature and scope of the debates around the competition vary widely. If the legalistic approach dominates, it tends to limit interactions. However if the contracting authority adopts a more open approach to the competition, from programming to the dissemination and capitalisation of its results, it can make a real process of collective deliberation and favour the growth of shared competence
Atomic Dipole Traps with Amplified Spontaneous Emission: A Proposal
We propose what we believe to be a novel type of optical source for
ultra-cold atomic Far Off-Resonance optical-dipole Traps (FORTs). The source is
based on an Erbium Amplified Spontaneous Emission (ASE) source that seeds a
high power Erbium Doped Fiber Amplifier (EDFA). The main interest of this
source is its very low coherence length, thus allowing an incoherent
superposition of several trapping beams without any optical interference. The
behavior of the superimposed beams is then a scalar sum greatly simplifying
complex configurations. As an illustration, we report an estimation of the
intensity noise of this source and an estimation of the atomic excess heating
rate for an evaporative cooling experiment application. They are both found to
be suitable for cold atoms experiments
Prévision de l'échauffement et de la microplasticité des aciers sous sollicitations cycliques
L'élévation de température dans les aciers sous chargement cyclique est une manifestation de l'existence de mécanismes irréversibles qui sont aussi à l'origine de l'amorçage des microfissures. Ainsi, afin d'optimiser la microstructure des aciers pour le comportement en fatigue, un modèle polycristallin est proposé pour mieux comprendre les interactions entre les mécanismes dissipatifs et la microstructure. Le cadre de la plasticité cristalline est utilisé pour décrire ces mécanismes dissipatifs qui sont soit dus à des oscillations de segments de dislocations, soit dus au glissement plastique. Le modèle ainsi développé est validé au travers d'une comparaison avec des résultats expérimentaux
The French EO high spatial resolution hyperspectral dual mission - an update
More than 25 years of airborne imaging spectroscopy and spaceborne sensors such as Hyperion [1] or HICO [2] have clearly demonstrated the ability of such a remote sensing technique to produce value added information regarding surface composition and physical properties for a large variety of applications [3]. Scheduled missions such as EnMAP [4], HISUI [5] or PRISMA [6] prove the increased interest of the scientific community for such a type of remote sensing data. In France, after gathering a group of Science and Defence users of imaging spectrometry data (Groupe de Synthèse Hyperspectral, GSH [7]) to establish an up-to-date review of possible applications, define instrument specifications required for accurate, quantitative retrieval of diagnostic parameters, and identify fields of application where imaging spectrometry is a major contribution, CNES (French Space Agency) decided a pre-phase A study for an hyperspectral mission concept called HYPXIM (HYPerspectral-X IMagery), the main fields of applications of which were to be vegetation, coastal and inland waters, geosciences, urban environment, atmospheric sciences, cryosphere and Defence. During this pre-phase A, the feasibility of such a platform was evaluated, based on specific studies supported by Defence and a more accurate definition of reference radiances and instrument characteristics. Results also pointed to applications where high spatial resolution was necessary and would not be covered by the other foreseen hyperspectral missions. For example, in the case of ecosystem studies, it is generally agreed that many model variables and processes are not accurately represented and that upcoming sensors with improved spatial and spectral capabilities, such as higher resolution imaging spectrometers, are needed to further improve the quality and accuracy of model variables [8, 9]. The growing interest for urban environment related applications also emphasized the need for an increased spatial resolution [10, 11]. Finally, short revisit time is an issue for security and Defense as well as crisis monitoring. Table 1 summarizes the Science and Defence mission requirements at the end of pre-phase A.
Two instrument designs were proposed by the industry (EADS-Astrium and Thales Alenia Space) based on these new requirements [12]: HYPXIM-Challenging, on a micro-satellite platform, with a 15 m pixel and HYPXIM-Performance, on a mini-satellite platform, with a 8 m pixel, and possible TIR hyperspectral capabilities. Both scenarios included a PAN camera with a 1.85 m pixel. Platform agility would allow for “on-event mode” with a 3-day revisit time. CNES decided to select HYPXIM-Performance, the system providing a higher spatial resolution (pixel ≤ 8 m, [13, 14]), but without TIR capabilities, for a phase A study [15]. This phase A was to start at the beginning of 2013 but is currently stopped due to budget constraints. An important part of the activities has been focusing on getting the French community more involved through various surveys and workshops in preparation for the CNES prospective meeting, an important step for the future of the mission. During this prospective meeting, which took place last March, decision was taken to keep HYPXIM alive as a mid-term (2020-2025) mission. The attendance at the recent workshop organized by the SFPT-GH (Société Française de Photogrammétrie et Télédétection, Groupe Hyperspectral) which gathered more than 90 participants from various field of application, including the industry (see http://www.sfpt.fr/hyperspectral for more details), demonstrates the interest and support of the French scientific community for a high spatial resolution imaging spectrometry mission
Hepatic Stem-like Phenotype and Interplay of Wnt/β-Catenin and Myc Signaling in Aggressive Childhood Liver Cancer
SummaryHepatoblastoma, the most common pediatric liver cancer, is tightly linked to excessive Wnt/β-catenin signaling. Here, we used microarray analysis to identify two tumor subclasses resembling distinct phases of liver development and a discriminating 16-gene signature. β-catenin activated different transcriptional programs in the two tumor types, with distinctive expression of hepatic stem/progenitor markers in immature tumors. This highly proliferating subclass was typified by gains of chromosomes 8q and 2p and upregulated Myc signaling. Myc-induced hepatoblastoma-like tumors in mice strikingly resembled the human immature subtype, and Myc downregulation in hepatoblastoma cells impaired tumorigenesis in vivo. Remarkably, the 16-gene signature discriminated invasive and metastatic hepatoblastomas and predicted prognosis with high accuracy
Actin-Related Protein Arp6 Influences H2A.Z-Dependent and -Independent Gene Expression and Links Ribosomal Protein Genes to Nuclear Pores
Actin-related proteins are ubiquitous components of chromatin remodelers and are conserved from yeast to man. We have examined the role of the budding yeast actin-related protein Arp6 in gene expression, both as a component of the SWR1 complex (SWR-C) and in its absence. We mapped Arp6 binding sites along four yeast chromosomes using chromatin immunoprecipitation from wild-type and swr1 deleted (swr1Δ) cells. We find that a majority of Arp6 binding sites coincide with binding sites of Swr1, the catalytic subunit of SWR-C, and with the histone H2A variant Htz1 (H2A.Z) deposited by SWR-C. However, Arp6 binding detected at centromeres, the promoters of ribosomal protein (RP) genes, and some telomeres is independent of Swr1 and Htz1 deposition. Given that RP genes and telomeres both show association with the nuclear periphery, we monitored the ability of Arp6 to mediate the localization of chromatin to nuclear pores. Arp6 binding is sufficient to shift a randomly positioned locus to nuclear periphery, even in a swr1Δ strain. Arp6 is also necessary for the pore association of its targeted RP promoters possibly through cell cycle-dependent factors. Loss of Arp6, but not Htz1, leads to an up-regulation of these RP genes. In contrast, the pore-association of GAL1 correlates with Htz1 deposition, and loss of Arp6 reduces both GAL1 activation and peripheral localization. We conclude that Arp6 functions both together with the nucleosome remodeler Swr1 and also without it, to mediate Htz1-dependent and Htz1-independent binding of chromatin domains to nuclear pores. This association is shown to have modulating effects on gene expression
Enseignants et enseignements au cœur de la transmission des savoirs
Ce recueil est consacré à la question de la transmission des savoirs abordée non pas comme un transfert individuel, de personne à personne, dans le cadre de la famille ou de l’atelier, mais comme un système formel combinant de façon plus structurée un ou des enseignements. Cette problématique a fait l’objet de très nombreuses conférences, d’une extrême diversité, présentées lors du 143e Congrès national des sociétés historiques et scientifiques tenu à Paris, en 2018. Leur point commun est principalement de s’interroger sur la transmission des savoirs par l’enseignement, son éventuelle formalisation, ses acteurs, ses méthodes et ses outils, voire ses enjeux. Le Congrès national des sociétés historiques et scientifiques rassemble chaque année universitaires, membres de sociétés savantes et jeunes chercheurs. Ce recueil est issu de travaux présentés lors du 143e Congrès sur le thème « La transmission des savoirs »
Maternal outcomes and risk factors for COVID-19 severity among pregnant women.
Pregnant women may be at higher risk of severe complications associated with the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which may lead to obstetrical complications. We performed a case control study comparing pregnant women with severe coronavirus disease 19 (cases) to pregnant women with a milder form (controls) enrolled in the COVI-Preg international registry cohort between March 24 and July 26, 2020. Risk factors for severity, obstetrical and immediate neonatal outcomes were assessed. A total of 926 pregnant women with a positive test for SARS-CoV-2 were included, among which 92 (9.9%) presented with severe COVID-19 disease. Risk factors for severe maternal outcomes were pulmonary comorbidities [aOR 4.3, 95% CI 1.9-9.5], hypertensive disorders [aOR 2.7, 95% CI 1.0-7.0] and diabetes [aOR2.2, 95% CI 1.1-4.5]. Pregnant women with severe maternal outcomes were at higher risk of caesarean section [70.7% (n = 53/75)], preterm delivery [62.7% (n = 32/51)] and newborns requiring admission to the neonatal intensive care unit [41.3% (n = 31/75)]. In this study, several risk factors for developing severe complications of SARS-CoV-2 infection among pregnant women were identified including pulmonary comorbidities, hypertensive disorders and diabetes. Obstetrical and neonatal outcomes appear to be influenced by the severity of maternal disease
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