A simple derivation of BV bounds for inhomogeneous relaxation systems

We consider relaxation systems of transport equations with heterogeneous source terms and with boundary conditions, which limits are scalar conservation laws. Classical bounds fail in this context and in particular BV estimates. They are the most standard and simplest way to prove compactness and convergence. We provide a novel and simple method to obtain partial BV regularity and strong compactness in this framework. The standard notion of entropy is not convenient either and we also indicate another, but closely related, notion. We give two examples motivated by renal flows which consist of 2 by 2 and 3 by 3 relaxation systems with 2-velocities but the method is more general

Large-scale morphodynamics structures in the Arc en Maurienne River (France)

Water Qualit

Structural properties of a calcium aluminosilicate glass from molecular-dynamics simulations: A finite size effects study

We study a calcium aluminosilicate glass of composition (SiO$_2$)$_{0.67}$-(Al$_2$O$_3$)$_{0.12}$-(CaO)$_{0.21}$ by means of molecular-dynamics (MD) simulations, using a potential made of two-body and three-body interactions. In order to prepare small samples that can subsequently be studied by first-principles, the finite size effects on the liquid dynamics and on the glass structural properties are investigated. We find that finite size effects affect the Si-O-Si and Si-O-Al angular distributions, the first peaks of the Si-O, Al-O and Ca-O pair correlation functions, the Ca coordination and the oxygen atoms environment in the smallest system (100 atoms). We give evidence that these finite size effects can be directly attributed to the use of three-body interactions.Comment: 36 pages, 14 figures. Journal of Chem. Phys., in pres

La construction sociale du marché du handicap : entre concurrence associative et régulation politique (1943-2009)

Les équipements du secteur du handicap sont gérés en France par des acteurs associatifs, qui représentent les trois quarts des opérateurs. Essentiellement financées par des fonds publics, ces organisations privées agissent selon des règles propres au secteur. Mais l'introduction des appels à projets (loi HPST de 2009) cristallise les débats sur la création d'un " marché du handicap " et l'instauration d'une logique concurrentielle entre les associations. Prenant de la distance à l'égard de ces débats, l'objectif de la recherche est de proposer une analyse des processus de transformations des comportements économiques des associations dans le secteur du handicap que nous avons considéré comme un champ organisationnel. Adoptant une approche longitudinale à l'aide d'une part d'une enquête sur les données de l'évolution de l'équipement dans deux départements de la région Rhône-Alpes depuis les années quarante et d'autre part d'une enquête par entretiens auprès d'une soixantaine d'acteurs du champ, cette recherche met en évidence trois résultats. (1) Les luttes concurrentielles, même si elles ont toujours existé dans le champ connaissent des évolutions dans le temps. D'une part elles s'intensifient dans le sens où les opérateurs associatifs s'implantent sur des territoires de concurrence occupés par d'autres et que des ententes implicites protégeaient jusque là de toute nouvelle intrusion. D'autre part, de nouvelles stratégies de lutte concurrentielle émergent : actions sur les coûts et la qualité et prise de contrôle directe sur d'autres opérateurs dans le cadre de fusions-acquisitions (2) Ces nouvelles formes de luttes économiques se diffusent car elles sont soutenues par une nouvelle conception de contrôle " managériale " en émergence qui valorise les comportements de recherche d'efficience, de rationalisation et de rapprochement associatifs. Cette conception de contrôle est soutenue par de nouveaux acteurs clés du champ, issus eux-mêmes des transformations des rapports de pouvoir interne aux opérateurs associatifs (la prise de pouvoir des dirigeants salariés, professionnels de la gestion, sur les dirigeants bénévoles) et des transformations des modes d'intervention des autorités publiques (instruments de contrôle à distance mobilisés par les représentants des autorités publiques). (3) Ces nouvelles formes de lutte économiques ont des effets de stabilisation des rapports de pouvoir dans le champ, autrement dit des positions acquises au cours de la première phase de structuration du champ. Ce travail pourrait ouvrir plusieurs perspectives de recherche. La principale consiste en une exploitation approfondie des données statistiques que nous avons recueillies pour constituer une base de données longitudinales sur l'offre d'équipement dans deux départements de manière à mieux rendre compte des transformations qui affectent les luttes concurrentielles entre opérateurs associatifs. Ce travail soulève par ailleurs des questions sur la façon dont l'information sur l'équipement dans le secteur du handicap est construite et utilisée par les acteurs. Des recherches sur la construction et les usages des nomenclatures officielles (de type FINESS) et leur articulation avec les classements " indigènes " produits par les acteurs de terrain peuvent notamment aider à comprendre certains décalages entre les " besoins " et les équipements créés

Ion Beam Radiation Effects in Monazite.

International audienceMonazite is a potential matrix for conditioning minor actinides arising from spent fuel reprocessing. The matrix behavior under irradiation must be investigated to ensure long-term containment performance. Monazite compounds were irradiated by gold and helium ions to simulate the consequences of alpha decay. This article describes the effects of such irradiation on the structural and macroscopic properties (density, hardness) of monazites LaPO4 and La0.73Ce0.27PO4. Irradiation by gold ions results in major changes in the material properties. At a damage level of 6.7 dpa, monazite exhibits volume expansion of about 8.1%, a 59% drop in hardness, and structure amorphization, although Raman spectroscopy analysis shows that the phosphate-oxygen bond is unaffected. Conversely, no change in the properties of these compounds was observed after He ion implantation. These results indicate that ballistic effects predominate in the studied dose range

First-principles molecular-dynamics simulations of a hydrous silica melt: Structural properties and hydrogen diffusion mechanism

We use {\it ab initio} molecular dynamics simulations to study a sample of liquid silica containing 3.84 wt.% H$_2$O.We find that, for temperatures of 3000 K and 3500 K,water is almost exclusively dissolved as hydroxyl groups, the silica network is partially broken and static and dynamical properties of the silica network change considerably upon the addition of water.Water molecules or free O-H groups occur only at the highest temperature but are not stable and disintegrate rapidly.Structural properties of this system are compared to those of pure silica and sodium tetrasilicate melts at equivalent temperatures. These comparisons confirm the picture of a partially broken tetrahedral network in the hydrous liquid and suggest that the structure of the matrix is as much changed by the addition of water than it is by the addition of the same amount (in mole %) of sodium oxide. On larger length scales, correlations are qualitatively similar but seem to be more pronounced in the hydrous silica liquid. Finally, we study the diffusion mechanisms of the hydrogen atoms in the melt. It turns out that HOSi$_2$ triclusters and SiO dangling bonds play a decisive role as intermediate states for the hydrogen diffusion.Comment: 25 pages, 18 figures. submitte

Massively multiplayer online role-playing games: comparing characteristics of addict vs non-addict online recruited gamers in a French adult population

<p>Abstract</p> <p>Background</p> <p>Massively Multiplayer Online Role-Playing Games (MMORPGs) are a very popular and enjoyable leisure activity, and there is a lack of international validated instruments to assess excessive gaming. With the growing number of gamers worldwide, adverse effects (isolation, hospitalizations, excessive use, etc.) are observed in a minority of gamers, which is a concern for society and for the scientific community. In the present study, we focused on screening gamers at potential risk of MMORPG addiction.</p> <p>Methods</p> <p>In this exploratory study, we focused on characteristics, online habits and problematic overuse in adult MMORPG gamers. In addition to socio-demographical data and gamer behavioral patterns, 3 different instruments for screening addiction were used in French MMORPG gamers recruited online over 10 consecutive months: the substance dependence criteria for the Diagnostic and Statistical Manual of Mental Disorder, fourth revised edition (DSM-IV-TR) that has been adapted for MMORPG (DAS), the qualitative Goldberg Internet Addiction Disorder scale (GIAD) and the quantitative Orman Internet Stress Scale (ISS). For all scales, a score above a specific threshold defined positivity.</p> <p>Results</p> <p>The 448 participating adult gamers were mainly young adult university graduates living alone in urban areas. Participants showed high rates of both Internet addiction (44.2% for GIAD, 32.6% for ISS) and DAS positivity (27.5%). Compared to the DAS negative group, DAS positive gamers reported significantly higher rates of tolerance phenomenon (increased amount of time in online gaming to obtain the desired effect) and declared significantly more social, financial (OR: 4.85), marital (OR: 4.61), family (OR: 4.69) and/or professional difficulties (OR: 4.42) since they started online gaming. Furthermore, these gamers self-reported significantly higher rates (3 times more) of irritability, daytime sleepiness, sleep deprivation due to play, low mood and emotional changes since online gaming onset.</p> <p>Conclusions</p> <p>The DAS appeared to be a good first-line instrument to screen MMORPG addiction in online gamers. This study found high MMORPG addiction rates, and self-reported adverse symptoms in important aspects of life, including mood and sleep. This confirms the need to set up relevant prevention programs against online game overuse.</p

Signature of small rings in the Raman spectra of normal and compressed amorphous silica: A combined classical and ab initio study

We calculate the parallel (VV) and perpendicular (VH) polarized Raman spectra of amorphous silica. Model SiO2 glasses, uncompressed and compressed, were generated by a combination of classical and ab initio molecular-dynamics simulations and their dynamical matrices were computed within the framework of the density functional theory. The Raman scattering intensities were determined using the bond-polarizability model and a good agreement with experimental spectra was found. We confirm that the modes associated to the fourfold and threefold rings produce most of the Raman intensity of the D1 and D2 peaks, respectively, in the VV Raman spectra. Modifications of the Raman spectra upon compression are found to be in agreement with experimental data. We show that the modes associated to the fourfold rings still exist upon compression but do not produce a strong Raman intensity, whereas the ones associated to the threefold rings do. This result strongly suggests that the area under the D1 and D2 peaks is not directly proportional to the concentration of small rings in amorphous SiO2.Comment: 21 pages, 8 figures. Phys. Rev. B, in pres

Sepsis and septic shock in patients with malignancies : a Groupe de Recherche Respiratoire en Réanimation Onco-Hématologique study

Objectives: Cancer affects up to 20% of critically ill patients, and sepsis is one of the leading reasons for ICU admission in this setting. Early signals suggested that survival might be increasing in this population. However, confirmation studies have been lacking. The goal of this study was to assess trends in survival rates over time in cancer patients admitted to the ICU for sepsis or septic shock over the last 2 decades. Data Source: Seven European ICUs. Study Selection: A hierarchical model taking into account the year of admission and the source dataset as random variables was used to identify risk factors for day 30 mortality. Data Extraction: Data from cancer patients admitted to ICUs for sepsis or septic shock were extracted from the Groupe de Recherche Respiratoire en Reanimation Onco-Hematologique database (1994-2015). Data Synthesis: Overall, 2,062 patients (62% men, median [interquartile range] age 59 yr [48-67 yr]) were included in the study. Underlying malignancies were solid tumors (n = 362; 17.6%) or hematologic malignancies (n = 1,700; 82.4%), including acute leukemia (n = 591; 28.7%), non-Hodgkin lymphoma (n = 461; 22.3%), and myeloma (n = 244; 11.8%). Two-hundred fifty patients (12%) underwent allogeneic hematopoietic stem cell transplantation and 640 (31.0%) were neutropenic at ICU admission. Day 30 mortality was 39.9% (823 deaths). The year of ICU admission was associated with significant decrease in day 30 mortality over time (odds ratio, 0.96; 95% CI, 0.93-0.98; p = 0.001). Mechanical ventilation (odds ratio, 3.25; 95% CI, 2.52-4.19; p < 0.01) and vasopressors use (odds ratio, 1.42; 95% CI, 1.10-1.83; p < 0.01) were independently associated with day 30 mortality, whereas underlying malignancy, allogeneic hematopoietic stem cell transplantation, and neutropenia were not. Conclusions: Survival in critically ill oncology and hematology patients with sepsis improved significantly over time. As outcomes improve, clinicians should consider updating admission policies and goals of care in this population

Cadmium triggers an integrated reprogramming of the metabolism of Synechocystis PCC6803, under the control of the Slr1738 regulator

<p>Abstract</p> <p>Background</p> <p>Cadmium is a persistent pollutant that threatens most biological organisms, including cyanobacteria that support a large part of the biosphere. Using a multifaceted approach, we have investigated the global responses to Cd and other relevant stresses (H₂O₂and Fe) in the model cyanobacterium <it>Synechocystis </it>PCC6803.</p> <p>Results</p> <p>We found that cells respond to the Cd stress in a two main temporal phases process. In the "early" phase cells mainly limit Cd entry through the negative and positive regulation of numerous genes operating in metal uptake and export, respectively. As time proceeds, the number of responsive genes increases. In this "massive" phase, Cd downregulates most genes operating in (i) photosynthesis (PS) that normally provides ATP and NADPH; (ii) assimilation of carbon, nitrogen and sulfur that requires ATP and NAD(P)H; and (iii) translation machinery, a major consumer of ATP and nutrients. Simultaneously, many genes are upregulated, such as those involved in Fe acquisition, stress tolerance, and protein degradation (crucial to nutrients recycling). The most striking common effect of Cd and H₂O₂is the disturbance of both light tolerance and Fe homeostasis, which appeared to be interdependent. Our results indicate that cells challenged with H₂O₂or Cd use different strategies for the same purpose of supplying Fe atoms to Fe-requiring metalloenzymes and the SUF machinery, which synthesizes or repairs Fe-S centers. Cd-stressed cells preferentially breakdown their Fe-rich PS machinery, whereas H₂O₂-challenged cells preferentially accelerate the intake of Fe atoms from the medium.</p> <p>Conclusion</p> <p>We view the responses to Cd as an integrated "Yin Yang" reprogramming of the whole metabolism, we found to be controlled by the Slr1738 regulator. As the Yin process, the ATP- and nutrients-sparing downregulation of anabolism limits the poisoning incorporation of Cd into metalloenzymes. As the compensatory Yang process, the PS breakdown liberates nutrient assimilates for the synthesis of Cd-tolerance proteins, among which we found the Slr0946 arsenate reductase enzyme.</p