Growth Route Toward III-V Multispectral Solar Cells on Silicon

To date, high efficiency multijunction solar cells have been developed on Ge or GaAs substrates for space applications, and terrestrial applications are hampered by high fabrication costs. In order to reduce this cost, we propose a breakthrough technique of III-V compound heteroepitaxy on Si substrates without generation of defects critical to PV applications. With this technique we expect to achieve perfect integration of heterogeneous Ga1-xInxAs micro-crystals on Si substrates. In this paper, we show that this is the case for x=0. GaAs crystals were grown by Epitaxial Lateral Overgrowth on Si (100) wafers covered with a thin SiO2 nanostructured layer. The cristallographic structure of these crystals is analysed by MEB and TEM imaging. Micro-Raman and Micro-Photomuminescence spectra of GaAs crystals grown with different conditions are compared with those of a reference GaAs wafer in order to have more insight on eventual local strains and their cristallinity. This work aims at developping building blocks to further develop a GaAs/Si tandem demonstrator with a potential conversion efficiency of 29.6% under AM1.5G spectrum without concentration, as inferred from our realistic modeling. This paper shows that Epitaxial Lateral Overgrowth has a very interesting potential to develop multijunction solar cells on silicon approaching the today 30.3% world record of a GaInP/GaAs tandem cell under the same illumination conditions, but on a costlier substrate than silicon.Comment: Preprint of the 28th EUPVSEC proceedings, September 2013, Paris, France. (5 pages

Hubbert's Oil Peak Revisited by a Simulation Model

CERNA WORKING PAPER SERIES 2010-17As conventional oil reserves are declining, the debate on the oil production peak has become a burning issue. An increasing number of papers refer to Hubbert's peak oil theory to forecast the date of the production peak, both at regional and world levels. However, in our views, this theory lacks microeconomic foundations. Notably, it does not assume that exploration and production decisions in the oil industry depend on market prices. In an attempt to overcome these shortcomings, we have built an adaptative model, accounting for the behavior of one agent, standing for the competitive exploration-production industry, subjected to incomplete but improving information on the remaining reserves. Our work yields challenging results on the reasons for an Hubbert type peak oil, lying mainly "above the ground", both at regional and world levels, and on the shape of the production and marginal cost trajectories

Hubbert's Oil Peak Revisited by a Simulation Model

As conventional oil reserves are declining, the debate on the oil production peak has become a burning issue. An increasing number of papers refer to Hubbert's peak oil theory to forecast the date of the production peak, both at regional and world levels. However, in our views, this theory lacks microeconomic foundations. Notably, it does not assume that exploration and production decisions in the oil industry depend on market prices. In an attempt to overcome these shortcomings, we have built an adaptative model, accounting for the behavior of one agent, standing for the competitive exploration-production industry, subjected to incomplete but improving information on the remaining reserves. Our work yields challenging results on the reasons for an Hubbert type peak oil, lying mainly "above the ground", both at regional and world levels, and on the shape of the production and marginal cost trajectories.

Ampleur de la dengue dans la ville de Ouagadougou, Burkina-Faso, 2016: Magnitude of dengue fever in the city of Ouagadougou, Burkina-Faso, 2016

Introduction: En Octobre 2016, le Burkina Faso a connu une flambée de cas de dengue dont l’ampleur est peu connue. Aussi aucune étude n’a été réalisée durant les dix dernières années, donnant lieu à un manque d’information actualisée sur sa prévalence et son incidence. Cette étude avait pour objectif de déterminer l’ampleur de la dengue à Ouagadougou et le type de virus circulant. Méthodes: Nous avons mené une étude transversale sur les cas de dengue enregistrés dans les formations sanitaires (FS) de la ville de Ouagadougou du 1er août au 31 décembre 2016. Un cas de dengue était défini comme toute personne résident dans la ville de Ouagadougou présentant une maladie fébrile aiguë (2-7 jours), avec au moins deux des symptômes suivants : céphalées, douleur rétro-orbitale, myalgie, arthralgie, éruption cutanée, manifestations hémorragiques, syndrome de choc et un test biologique positif à la PCR ou avec TDR-Dengue positif ayant un lien épidémiologique avec un cas confirmé. Nous avons réalisé une recherche active des cas à travers une revue documentaire des registres de laboratoire, consultation et/ou d’hospitalisation des FS, Une fiche de collecte a été utilisée pour recueillir les caractéristiques sociodémographiques, cliniques, biologiques des cas. Résultats: Au total, 5094 cas de dengue ont été enregistrés dans les FS. L’âge médian était de 27 ans avec un intervalle interquartile de 16 à 37 ans. Quinze cas (51,72%) ont été testés positifs à la PCR dont 10 (66,67%) au DENV2 et 5 (33,33%) au DENV3. Parmi les cas, 2569 (50,76%) étaient de sexe féminin et 1494 (28,16%) cas avaient été hospitalisés. Sur les cas recensés, 73% avaient été notifiés par les structures privées et 3174 (88,88%) étaient des éleves/étudiants ou fonctionnaires ou commerçants. Le taux d’attaque global était de 201 cas (5094/2532311) pour 100000 habitants. Le taux de létalité était de 35/5094 (0,69%). Conclusion: Le taux d’attaque global de la dengue en 2016 était de 201 cas pour 100000 habitants. La dengue touchait plus les adultes jeunes surtout les élèves/étudiants et les fonctionnaires et était causée par les types 2 et 3. Les cas étaient plus notifiés par les structures privées. Une surveillance hebdomadaire associée à une surveil-lance sentinelle et la sensibilisation de la population sur la dengue contribueraient à endiguer ce fléau au Burki-na Faso. Background: In October 2016, Burkina Faso experienced an outbreak of dengue fever that the magnitude is little known. Also, no studies have been performed in the past ten years, giving rise to a lack of updated information on its prevalence and incidence. We conducted an investigation to determine the magnitude of dengue fever in Ouagadougou’s city and the type of virus circulating. Methods: We conducted a cross-sectional study on the cases of dengue recorded in health facilities (HF) in Ouagadougou’s city from August 1st to December 31st, 2016. We defined a case of dengue as any person resident in the city of Ouagadougou with acute febrile illness (2-7days), with at least two of the following symptoms (headache, retro-orbital pain, myalgia, arthralgia, rash, hemorrhagic manifestations, shock syndrome) and a positive PCR test or with dengue-RDT positive, having an epidemiological link with a confirmed case. We carried out an active search for cases through a documentary review of laboratory, consultation and/or hospitalization registers of HF, used a file to collect the socio-demographic, clinical and biological characteristics of the cases. Results: A total of 5094 cases of dengue fever were recorded in the HF. The median age was 27 years with an interquartile range of 16 to 37 years old. Fifteen (51.72%) cases tested positive with PCR including 10(66.67%) for DENV2 and 5(33.33%) for DENV3. Among the cases, 2,569(50.76%) were female and 1,494(28.16%) cases were hospitalized. Of the cases listed, 73% were notified by private’s hospitals and 3,174 (88.88%) were pupils/students or civil servants or traders. The overall attack rate was 201 cases (5094/2532311) per 100,000 populations. The case fatality rate was 35/5094 (0.69%). Conclusion: The overall dengue attack rate in 2016 was 201 cases per 100,000 populations. Dengue more affected young adults especially the pupils/students or civil servants and was caused by types 2 and 3. The cases were more notified by the private hospitals. We recommend weekly surveillance, sentinel surveillance and public awareness of dengue fever

Bone Marrow Transplant

Mucopolysaccharidosis type I-H (MPS I-H) is a rare lysosomal storage disorder caused by α-L-Iduronidase deficiency. Early haematopoietic stem cell transplantation (HSCT) is the sole available therapeutic option to preserve neurocognitive functions. We report long-term follow-up (median 9 years, interquartile range 8-16.5) for 51 MPS I-H patients who underwent HSCT between 1986 and 2018 in France. 4 patients died from complications of HSCT and one from disease progression. Complete chimerism and normal α-L-Iduronidase activity were obtained in 84% and 71% of patients respectively. No difference of outcomes was observed between bone marrow and cord blood stem cell sources. All patients acquired independent walking and 91% and 78% acquired intelligible language or reading and writing. Intelligence Quotient evaluation (n = 23) showed that 69% had IQ ≥ 70 at last follow-up. 58% of patients had normal or remedial schooling and 62% of the 13 adults had good socio-professional insertion. Skeletal dysplasia as well as vision and hearing impairments progressed despite HSCT, with significant disability. These results provide a long-term assessment of HSCT efficacy in MPS I-H and could be useful in the evaluation of novel promising treatments such as gene therapy

Search for dark matter produced in association with bottom or top quarks in √s = 13 TeV pp collisions with the ATLAS detector

A search for weakly interacting massive particle dark matter produced in association with bottom or top quarks is presented. Final states containing third-generation quarks and miss- ing transverse momentum are considered. The analysis uses 36.1 fb−1 of proton–proton collision data recorded by the ATLAS experiment at √s = 13 TeV in 2015 and 2016. No significant excess of events above the estimated backgrounds is observed. The results are in- terpreted in the framework of simplified models of spin-0 dark-matter mediators. For colour- neutral spin-0 mediators produced in association with top quarks and decaying into a pair of dark-matter particles, mediator masses below 50 GeV are excluded assuming a dark-matter candidate mass of 1 GeV and unitary couplings. For scalar and pseudoscalar mediators produced in association with bottom quarks, the search sets limits on the production cross- section of 300 times the predicted rate for mediators with masses between 10 and 50 GeV and assuming a dark-matter mass of 1 GeV and unitary coupling. Constraints on colour- charged scalar simplified models are also presented. Assuming a dark-matter particle mass of 35 GeV, mediator particles with mass below 1.1 TeV are excluded for couplings yielding a dark-matter relic density consistent with measurements