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Printemps et islamisme : premières leçons pour les Frères musulmans
No full textInternational audienceLe « printemps arabe », inauguré le 14 janvier 2011 par la déroute du président tunisien Zine El-Abidine Ben Ali, a fait inopinément entr’apercevoir dans la région la fin d’un long “hiver autoritaire”. La dynamique protestataire était initialement caractérisée par l’absence d’encadrement de la part des oppositions partisanes préexistantes et l’usage de mots d’ordre (“dignité”, “liberté”, “dégage”) dont aucune d’entre elles ne pouvait revendiquer le monopole. Par la suite, les acteurs usant du lexique de l’islam politique - les Frères musulmans, mais également, en Egypte, certains des salafistes nouvellement acquis, mais sur des lignes divergentes, à l’action politique- ont joué un peu partout des rôles de premier plan. Au terme de plusieurs décennies d’ostracisation, ou d’interdiction, les islamistes ont été non seulement intégrés aux consultations électorales, mais ils ont de surcroît réussi un peu partout à les remporter. Leur capacité à « jouer le jeu » du pluralisme naissant a démenti ensuite la doxa des prophéties pessimistes qui ne les cantonnait qu’au seul registre de la violence..
Can volume predict Bitcoin returns and volatility? A quantiles-based approach
No full textInternational audiencePrior studies on the price formation in the Bitcoin market consider the role of Bitcoin transactions at the conditional mean of the returns distribution. This study employs in contrast a non-parametric causality-in-quantiles test to analyse the causal relation between trading volume and Bitcoin returns and volatility, over the whole of their respective conditional distributions. The nonparametric characteristics of our test control for misspecification due to nonlinearity and structural breaks, two features of our data that cover 19th December 2011 to 25th April 2016. The causality-in-quantiles test reveals that volume can predict returns- except in Bitcoin bear and bull market regimes. This result highlights the importance of modelling nonlinearity and accounting for the tail behaviour when analysing causal relationships between Bitcoin returns and trading volume. We show, however, that volume cannot help predict the volatility of Bitcoin returns at any point of the conditional distribution
Uncovering frequency domain causality between gold and the stock markets of China and India: Evidence from implied volatility indices
No full textInternational audienceWe use implied volatility indices and examine short-term and long-term causality dynamics between gold and the Chinese and Indian stock markets from March 2011 to March 2017. We uncover some interesting predictability patterns that differ along the spectrum. Importantly, we find significant bi-directional effects between gold and the Chinese and Indian stock markets in both high and low frequencies, suggesting that the safe-haven property of gold is not stable. Our results are robust in the out-of-sample forecasting exercises
Essential oils composition and antimicrobial activity of six conifers harvested in Lebanon
No full textInternational audienceThe chemical composition and antimicrobial activity of the essential oils (EOs) of six conifers harvested in Lebanon, Abies cilicica, Cupressus sempervirens, Juniperus excelsa, Juniperus oxycedrus, Cedrus libani and Cupressus macrocarpa gold crest, were investigated. The EOs were obtained by hydrodistillation using a Clevenger-type apparatus and characterized by GC and GC/MS analyses. A principal components analysis based on Pearson correlation between essential oils chemical analyses was also conducted. The minimum inhibitory concentrations (MICs) of these essentials oils were determined against a range of bacteria and fungi responsible for cutaneous infections in human, using the broth microdilution technique. The EOs showed the most interesting bioactivity on the dermatophytes species (MIC values 32 – 64 μg/ml). Each of the major compounds of C. macrocarpa as well as an artificial reconstructed EO were tested on Trichophyton rubrum showing a contribution of the minor components to the overall activity
On the hedge and safe haven properties of Bitcoin: Is it really more than a diversifier?
No full textInternational audienceThis paper uses a dynamic conditional correlation model to examine whether Bitcoin can act as a hedge and safe haven for major world stock indices, bonds, oil, gold, the general commodity index and the US dollar index. Daily and weekly data span from July 2011 to December 2015. Overall, the empirical results indicate that Bitcoin is a poor hedge and is suitable for diversification purposes only. However, Bitcoin can only serve as a strong safe haven against weekly extreme down movements in Asian stocks. We also show that Bitcoin hedging and safe haven properties vary between horizons
Changes in soil microbial substrate utilization in response to altered litter diversity and precipitation in a Mediterranean shrubland
No full textInternational audienceThis study aimed at quantifying the consequences of reduced precipitation and plant diversity on soil microbial community functioning in a Mediterranean shrubland of southern France. Across a natural gradient of shrub species diversity, we established a total of 92 plots (4 x 4 m) with and without a moderate rain exclusion treatment of about 12 % of total precipitation. Shrub diversity included all possible combinations of the four dominant species (Cistus albidus, Quercus coccifera, Rosmarinus officinalis, and Ulex parviflorus). Respective leaf litter mixtures of these species combinations were exposed in all plots over 2 years. We quantified how litter species richness and the reduction in precipitation affected the soil microbial substrate utilization (measured by CO2 evolution using the MicroResp method) on soil samples collected underneath each individual litter mixture after 1 and 2 years of decomposition. Moderate precipitation reduction had a minor impact, but litter species richness and the dissimilarity in phenolic concentrations (estimated using Rao's quadratic entropy) showed a positive effect on the diversity of substrates metabolized by the microbial communities. Moreover, litter species richness increased soil microbial activity by increasing the catabolic diversity of the soil microbial community. These effects were mostly driven by the presence of Quercus and Ulex leaf litter, which at the same time reduced microbial metabolic dominance, while the presence of Rosmarinus had opposite effects. Our data suggest that plant species loss can have stronger effects on the functioning of soil microbial communities than moderate drought, with potentially important feedbacks on biogeochemical cycling in Mediterranean shrubland ecosystems
The occurrence of maedi-visna virus in Lebanon
No full textInternational audienceMaedi-visna (MV) is a chronic viral disease prevalent in adult sheep that is caused by a virus belonging to the small ruminant lentivirus group (SRLV). This disease is considered to affect the international trade of sheep and is classified in the World Organisation for Animal Health (OIE) list of notifiable animal diseases. Although maedi-visna virus (MVV) has been detected in many countries, no study on its occurrence has been carried out in Lebanon. For this purpose, a serological survey of infection with MW was conducted in seven of the eight Lebanese governorates using a competitive enzyme-linked immunosorbent assay (ELISA). A total of 184 individual blood samples from sheep of the local breed 'Awassi', originating from 16 farms distributed throughout the seven Lebanese governorates, were collected and analysed. Among the 184 tested sheep, 131 sheep from the 16 farms visited were MVV positive. This presents a prevalence of 71% MW positive animals and 100% MVV-positive farms. The results indicate the need for further systematic investigations into the between-herd and within-herd prevalence of MV in Lebanon
Investigating a New Operating Point For PV Panels Seeking Maximum Life Span
No full textInternational audienceIn this paper we try to control the operation mode of PV panels to achieve a higher lifespan. In fact, PV panels are subject to several degradation modes: Potential Induced Degradation, Light Induced Degradation, UltraViolet Degradation, Moisture Induced Degradation, and cell cracks. The common factor that affects all the above degradation modes is temperature. In fact high temperatures lead to higher degradation process. In this paper we present an enhanced thermal model of PV panels. We simulate its behavior as a function of its operation. We define a new operating point to achieve a higher lifespan. Index Terms-degradation modes, temperature effect, thermal model, joule effect
