On simple arrangements of lines and pseudo-lines in P^2 and R^2 with the maximum number of triangles

We give some new advances in the research of the maximum number of triangles that we may obtain in a simple arrangements of n lines or pseudo-lines.Comment: 12 pages, 9 figure

Calibration of long-term global horizontal irradiation estimated by HelioClim-3 through short-term local measurement campaigns: extending of the results to European and African sites

International audienceThis paper proposes an adaptation of a recent ground-based short-term calibration algorithm applied to long-term time-series of global horizontal irradiation (GHI) provided by HelioClim-3 (HC3), a satellite-based surface solar irradiation database; it extends the initial conclusions for the South-East of France to a larger coverage. A first analysis of the long-term ground pyranometric measurements leads to the characterization of the clearness index error variability which confirms the systematic presence of, at least, a sinusoid component which period is equal to the astronomical year. On contrary of the first results based on the South-East of France, because the phasing of this sinusoid highly varies from one site to another, an adaptation of the original calibration procedure is proposed in order to have it applicable under different latitudes. The resulting mean bias error on the monthly GHI systematically goes below 3% when considering a 12-month local measurement campaign, while the seasonal variability of the error is drastically reduced

Les effets délétères de la pression académique sur la santé globale des étudiants du collégial

Affiche présentée dans le cadre du Colloque de l'ARC, «Des racines et des ailes pour la recherche collégiale», dans le cadre du 85e Congrès de l'Acfas, Université McGill, Montréal, les 8 et 9 mai 2017.Le profil des étudiants du collégial suit la tendance sociale au changement. Afin de mieux les connaître et de les aider à relever les défis, il est important de prendre en compte leur santé globale. Au cours de leur cheminement scolaire, ils subissent une pression académique pouvant nuire à leur développement et à leur réussite scolaire. Cette pression, bien qu'évidente dans la transition du secondaire au collégial, demeure peu étudiée. Elle peut amener l’étudiant à développer des troubles internalisés tels les troubles du comportement alimentaire (TCA), liés à des difficultés scolaires. Nous présenterons les résultats partiels d’une étude sur les précurseurs des TCA, soit les attitudes et comportements alimentaires inappropriés (ACAI). Un des objectifs est de mesurer la pression académique identifiée par ces étudiants (présence d’ACAI). Plusieurs étudiants issus de différentes filières ont été interrogés à l’aide de questionnaires psychométriques. Les résultats partiels indiquent la présence d’ACAI et des différences quant à leur présence et fréquence selon le programme suivi. Cette recherche, unique dans le milieu collégial, met en parallèle les pressions académiques perçues, la santé globale de l’étudiant et sa réussite scolaire pour proposer des recommandations à mettre en œuvre dans le milieu éducatif

Analysis of the long-term evolution of the solar resource in China and its main contributors

International audienceThis work analyses the long-term trend of the daily global (GHI) and diffuse (DHI) irradiations received on a horizontal plane for four cities in China: Harbin, Beijing, Wuhan and Guangzhou, located from North to South. Measurements of GHI and DHI between 1990 and 2013 have been retrieved from GEBA and WRDC networks. During this period, the yearly mean of the GHI increases for most of the sites (0.1 to 0.7% per year) except for Harbin for which it decreases (-0.4% per year) while the yearly mean of the DHI increases for all sites (0.2 to 0.9% per year). The effects of the aerosol optical depth at 550 nm and the cloud cover on such changes have been investigated. It has been found that aerosols have a direct impact on GHI in clear-sky conditions, especially for Beijing and Wuhan, and that the correlation is strong between the GHI measurements for all-sky conditions and aerosol optical depth at 550 nm. Expectedly, the correlation is much more significant between the GHI measurements and the cloud cover

Nouvelle intervention sur la mosaïque du sanctuaire de Mar Gabriel (Turquie orientale)

International audienc

Arginine methylation by PRMT1 regulates muscle stem cell fate

Quiescent muscle stem cells (MSCs) become activated in response to skeletal muscle injury to initiate regeneration. Activated MSCs proliferate and differentiate to repair damaged fibers or self-renew to maintain the pool and ensure future regeneration. The balance between self-renewal, proliferation, and differentiation is a tightly regulated process controlled by a genetic cascade involving determinant transcription factors such as Pax7, Myf5, MyoD, and MyoG. Recently, there have been several reports about the role of arginine methylation as a requirement for epigenetically mediated control of muscle regeneration. Here we report that the protein arginine methyltransferase 1 (PRMT1) is expressed in MSCs and that conditional ablation of PRMT1 in MSCs using Pax7CreERT2 causes impairment of muscle regeneration. Importantly, PRMT1-deficient MSCs have enhanced cell proliferation after injury but are unable to terminate the myogenic differentiation program, leading to regeneration failure. We identify the coactivator of Six1, Eya1, as a substrate of PRMT1. We show that PRMT1 methylates Eya1 in vitro and that loss of PRMT1 function in vivo prevents Eya1 methylation. Moreover, we observe that PRMT1- deficient MSCs have reduced expression of Eya1/Six1 target MyoD due to disruption of Eya1 recruitment at the MyoD promoter and subsequent Eya1-mediated coactivation. These findings suggest that arginine methylation by PRMT1 regulates muscle stem cell fate through the Eya1/Six1/MyoD axis

Interaction between MPI and TCP in grids.

As MPI applications are more and more resource consuming, they need to be executed on grids. The communications on the WAN interconnecting clusters mostly use TCP which suffers from WAN features: high latency, sharing between users, bandwidth smaller than the aggregate bandwidth of the nodes. In this report, we first study the interaction between MPI and TCP on grids. We show why the nature of MPI traffic raises problems while using TCP on WAN links. TCP's loss detection and congestion control mechanism can both slow down the application. Then, we propose MPI5000, a transparent applicative layer between MPI and TCP, using proxies to improve the execution of MPI applications on a grid. Proxies aim at splitting TCP connections in order to detect losses faster and avoid to return in a slowstart phase after an idle time. Finally, we test our layer on Grid'5000, the French research grid, using MPICH2. The results on the NPB (NAS Parallel Benchmarks) validate our architecture that reduces the number of idle timeout and the number of long-distance retransmissions for certain benchmarks, namely BT, SP and LU benchmarks. Using MPI5000, these applications can decrease their execution time by 35%, 28%, and, 15% respectively

Using models for predicting recovery and assess tree species vulnerability in logged tropical forests

Formålet med denne masteroppgaven er å analysere hvilke faktorer som påvirker kredittrangeringer og hvordan rangeringene er for Afrika (Sør for Sahara) i forhold til andre regioner. Ifølge Haque, Mark og Mathieson (2000) var Afrika (Sør for Sahara) regionen med lavest kredittrangeringer i perioden 1980 til 1993. Oppgaven undersøker om dette fortsatt er tilfelle i perioden 1990 til 2010 og videre hvilke faktorer som kan ligge til grunn for denne ulikheten. For å finne ut av dette forsøker jeg først å identifisere korrelasjonen mellom økonomiske, politiske og institusjonelle faktorer. Deretter undersøkes det om Afrika (Sør for Sahara) skiller seg negativt ut i forhold til andre regioner. Utgangspunkt til flere av forklaringsvariablene er hentet fra Cantor og Packer (1996) og Haque et al. (2000). Datamaterialet er samlet inn fra Verdensbanken, Institutional Investor, Det internasjonale pengefondet (IMF), Federal Reserve, Freedom House Index og Quality of Government Institute. Analysen er gjort ved hjelp av en fast effekt modell, der estimeringen er ved MKM og «Least squares dummy variable» (LSDV). Resultatene viser at det er noen få økonomiske variabler som bestemmer nesten 90 prosent av kredittrangeringene. Videre har Afrika (Sør for Sahara) fått lavere rangeringer enn andre regioner i perioden 1990 til 2010. Resultatene indikerer også at vektingen av de ulike variablene endres mellom land og over tid. Beregningene er gjort ved hjelp av Stata 13.1 og Excel 2010.ECON390MASV-SØ