Double scale analysis of periodic solutions of some non linear vibrating systems

We consider {\it small solutions} of a vibrating system with smooth non-linearities for which we provide an approximate solution by using a double scale analysis; a rigorous proof of convergence of a double scale expansion is included; for the forced response, a stability result is needed in order to prove convergence in a neighbourhood of a primary resonance.Comment: 36 page

Integrated management of water resources in Tafilalet (South-eastern Morocco); lessons of history

L’installation arabe du VIIIe siècle dans le Sud-est marocain présaharien a catalysé une conceptualisation de la configuration spatiale du Tafilalet, qui révèle des préoccupations d’exploitation des ressources naturelles, d’aménagement du territoire, de planification du développement économique, intimement lié à l’eau, et de gestion du risque environnemental. Les travaux que nous avons menés ces dernières décennies autour des interactions société-environnement des oasis du Sud-est marocain présaharien ont inscrit une avancée dans l’histoire comparée de l’environnement, dans la mesure où ils ont révélé des indicateurs souvent inédits de l’influence de l’héritage arabo-musulman médiéval sur les pratiques de gestion des ressources en eau, adaptés à des périodes ultérieures. Le rapport des populations du Tafilalet à l’eau constitue un aspect du patrimoine oasien. Le degré d’intégration des savoirs traditionnels de gestion dans les pratiques des sociétés modernes les érige en leçons du passé encore viables de nos jours.In the eighth century, the Arab settlement in the pre-Saharan southeastern Morocco led to the conceptualization of the Tafilelt’s spatial configuration; which reveals some concerns with regards to the exploitation of natural resources, land use, planning of economic development linked to water as well as environmental risk management. The number of research conducted during by the author in the last past decades, concerning the interactions between the society and the environment in the oases of the pre-Saharan south-eastern Morocco, helped improving the comparative history of the environment. This is in the sense that they revealed some unpublished indicators influencing the medieval Muslim Arab heritage on water resources management practices adapted to the future. The relationship between the Tafilelt population and water represents an important aspect of the oasis heritage. In fact, incorporating traditional management knowledge and skills into modern society is something playing in favor of the region’s success

Graphene-based amplification and tuning of near-field radiative heat transfer between dissimilar polar materials

The radiative heat transfer between two dielectrics can be strongly enhanced in the near field in the presence of surface phonon-polariton resonances. Nevertheless, the spectral mismatch between the surface modes supported by two dissimilar materials is responsible for a dramatic reduction of the radiative heat flux they exchange. In the present paper we study how the presence of a graphene sheet, deposited on the material supporting the surface wave of lowest frequency, allows to widely tune the radiative heat transfer, producing an amplification factor going up to one order of magnitude. By analyzing the Landauer energy transmission coefficients we demonstrate that this amplification results from the interplay between the delocalized plasmon supported by graphene and the surface polaritons of the two dielectrics. We finally show that the effect we highlight is robust with respect to the frequency mismatch, paving the way to an active tuning and amplification of near-field radiative heat transfer in different configurations.Comment: 8 pages, 8 figure

Silicifications du Jbel Ghassoul (bassin de Missour, Maroc) : les conditions de leur formation.

Les silicifications affectent indifféremment tous les faciès sédimentaires (calcaire lacustre, gypse et argilites). Elles sont sécantes sur les structures sédimentaires, aussi bien à l'échelle de l'affleurement que de la lame mince, et sont donc tardives post-sédimentaires. De plus elles sont limitées à la zone d'affleurement et disparaissent dès 20-40 m de profondeur comme le montre les nombreux travaux miniers. Les silicifications sont liées à des écoulements de nappe. La silice se dépose à proximité de l'affleurement, vraisemblablement par refroidissement de l'eau au contact des sols gelés pendant les périodes froides du Quaternaire

Temporal Variability of Rainfall Amounts and Trend Analysis in the Melloulou Watershed

The present study consists in analyzing the temporal variability of rainfall and rainfall trend a statistical analysis of rainfall data in the Melloulou watershed for a half-century chronicle (1970-2020). The objective of this study is to extract all the rainfall characteristics of this period, to extract the rainfall variability and to determine the rainfall trends. The working method is based on a statistical approach to detect the climatic characteristics of the Melloulou basin. The study of the standardized precipitation index (SPI) and the rainfall deficit index (IDF) showed the alternation of very long dry periods with wet periods. The Mann-Kendall test under the RStudio also showed a decreasing rainfall trend

Temporal Variability of Rainfall and Trend Analysis of Melloulou Watershed in Morocco

This paper focuses on analyzing the temporal variability of rainfall and rainfall trends using a statistical analysis of rainfall data in the Melloulou watershed for a half-century chronicle (1970-2020). The objective of this study is to extract all the rainfall characteristics and the rainfall variability during this period to determine the rainfall trends. The working method is based on a statistical approach to detect the climatic characteristics of the Melloulou basin. The study of the standardized precipitation index (SPI) and the rainfall deficit index (RDI) showed the alternation of very long dry periods with wet periods. The Mann-Kendall test under the RStudio also showed a decreasing rainfall trend

Technological advances: what hope for colorectal cancer?

Introduction: Colorectal cancers rank third in all cancers. Mass screening has proven effectiveness by significantly reducing incidence and mortality. If optical colonoscopy is the reference exam, virtual colonoscopy is an alternative of choice. We evaluate its first-line position in screening, following technological progress. Methods: We used PubMed's electronic search data from 2010. Among the 100 most consulted articles, have been studied those in English-language and which looked at screening in the population at average risk aged between 50 and 75 years , asymptomatic and dealing with optical and virtual colonoscopy. Studies in the symptomatic, high-risk, or very high-risk population or for diagnostic purposes were excluded. Results: in the USA, studies confirm the trend towards a decrease in incidence and mortality by colorectal cancers, shifting from 56.7 per 100,000 and 23.6 deaths respectively in 1992 to 36.5 per 100,000 and 14 deaths in 2015, thanks to the means of screening including the endoscopy. Although optical colonoscopy is the standard exam, virtual colonoscopy, with a specificity of 90% and a sensitivity of 85%, is becoming more and more a first-line means of screening for colorectal cancers. Conclusion: Thus, first-line endoscopic screening has proved its effectiveness in reducing morbidity and mortality by this cancer. However, the virtual endoscopy chosen by the National Comprehensive Cancer Network as a means of screening will undoubtedly constitute a strategy for the future, particularly in developing countries