SARA: A Students Space Initiative

SARA is a scientific small satellite initiated designed and assembled by students or just graduated post-students be project lasted 3 years in an aerospace club ESIEESPACE; a club created in an engineers school ESIEE ( Ecole Superieure d’Ingenieurs en Electronique et Electrotenique) near Paris. The purpose of SARA is to provide a long term survey of the decametric Surrounding radiations above ionosphere. Datas will be used by radioastronomers for a better understanding of the jovian atmosphere. SARA has been launched on July 16 1991 thanks to ARlANE at Kourou. It weight 26Kg, looks like a 35cm cube with three ten meter antennas. This project is an opportunity for a french space association to develop new ways to deal with space. SARA is also a new step in Microsat designing for educational activities which can lead to valuable experience to improve bigger projects

On stabilizability conditions for discrete-time switched linear systems

International audienceIn this paper we consider the stabilizability property for discrete-time switched linear systems. Novel conditions, in LMI form, are presented that permit to combine generality with computational affordability. The relations and implications between different conditions, new ones and taken from literature, for stabilizability are analyzed to infer and compare their conservatism and their complexity

Photodemethylation of methylmercury in Eastern Canadian Arctic thaw pond and lake ecosystems

Permafrost thaw ponds of the warming Eastern Canadian Arctic are major landscape constituents and often display high levels of methylmercury (MeHg). We examined photodegradation potentials in high-dissolved organic matter (DOC) thaw ponds on Bylot Island (BYL) and a low-DOC oligotrophic lake on Cornwallis Island (Char Lake). In BYL, the ambient MeHg photodemethylation (PD) rate over 48 h of solar exposure was 6.1 × 10–3 m2 E–1, and the rate in MeHg amended samples was 9.3 × 10–3 m2 E–1. In contrast, in low-DOC Char Lake, PD was only observed in the first 12 h, which suggests that PD may not be an important loss process in polar desert lakes. Thioglycolic acid addition slowed PD, while glutathione and chlorides did not impact northern PD rates. During an ecosystem-wide experiment conducted in a covered BYL pond, there was neither net MeHg increase in the dark nor loss attributable to PD following re-exposure to sunlight. We propose that high-DOC Arctic thaw ponds are more prone to MeHg PD than nearby oligotrophic lakes, likely through photoproduction of reactive species rather than via thiol complexation. However, at the ecosystem level, these ponds, which are widespread through the Arctic, remain likely sources of MeHg for neighboring systems

Radiation Effects in CMOS Isolation Oxides: Differences and Similarities With Thermal Oxides

Radiation effects in thick isolation oxides of modern CMOS technologies are investigated using dedicated test structures designed using two commercial foundries. Shallow Trench Isolation and Pre-Metal Dielectric are studied using electrical measurements performed after X-ray irradiations and isochronal annealing cycles. This paper shows that trapping properties of such isolation oxides can strongly differ from those of traditional thermal oxides usually used to process the gate oxide of Metal Oxide Semiconductor Field Effect Transistors. Buildup and annealing of both radiation-induced oxide-trap charge and radiation-induced interface traps are discussed as a function of the oxide type, foundry and bias condition during irradiation. Radiation-induced interface traps in such isolation oxides are shown to anneal below 100°C contrary to what is usually observed in thermal oxides. Implications for design hardening and radiation tests of CMOS Integrated Circuits are discussed

Identification of radiation induced dark current sources in pinned photodiode CMOS image sensors

This paper presents an investigation of Total Ionizing Dose induced dark current sources in Pinned PhotoDiodes (PPD) CMOS Image Sensors based on pixel design variations. The influence of several layout parameters is studied. Only one parameter is changed at a time enabling the direct evaluation of its contribution to the observed device degradation. By this approach, the origin of radiation induced dark current in PPD is localized on the pixel layout. The PPD peripheral STI does not seem to play a role in the degradation. The PPD area and an additional contribution independent on the pixel dimensions appear to be the main sources of the TID induced dark current increase

From swine to humans: the A (H1 N1) 2009 influenza pandemic

On April 25th 2009,Mexico notified theWHO of an outbreak of an influenza-like disease. The pathogen responsible was rapidly identified as an influenza virus of swine origin, the A (H1N1) 2009 influenza virus. The virus quickly spread worldwide, leading the WHO to announce a phase 6 pandemic alert on June 11th 2009. The majority of cases were mild, but 2 to 10 % of cases required hospitalization for respiratory distress, especially in children under 5, pregnant women, and patients with cardiovascular and respiratory diseases, diabetes or immunosuppression. By April 11th 2010, 17,798 deaths were officially notified to the WHO, a very low number compared to the usual death toll of seasonal influenza. This low death rate is due to the presence of immune resistance in the population over 60, a most likely consequence of sequence homologies between the 1918 and 2009 H1N1 pandemic viruses. Several anti-A (H1N1) 2009 vaccines were prepared in 2009, with and without adjuvants, and all were proven safe and immunogenic in Phase I/II studies carried out in volunteers. However, the vaccination campaign met little enthusiasm, for reasons which will be reported. Swine appear once more as an important potential reservoir for influenza virus strains pathogenic for man, an observation which pleads for enhanced virological surveillance in this species.Le 25 avril 2009, le Mexique notifiait l'OMS de l'apparition d'un foyer de maladie de type grippal. Le virus fut identifié peu de temps après comme un virus influenza d'origine porcine, le virus influenza A (H1N1) 2009. Celui-ci diffusa ensuite très rapidement dans le monde entier, conduisant l'OMS à déclarer dès le 11 juin 2009 le niveau 6 de pandémie. Bien que la majorité des cas cliniques aient été bénins, deux à 10 % ont nécessité une hospitalisation pour détresse respiratoire, notamment chez les enfants de moins de 5 ans, les femmes enceintes et les personnes souffrant de troubles cardiovasculaires ou pulmonaires, de diabète, ou d'immunodépression. Le nombre de décès dus à la grippe A (H1 N 1) 2009 officiellement notifiées à l'OMS au 11 avril 2010 ne s'élevait qu'à 17 798, un chiffre étonnamment bas par rapport aux chiffres habituels de mortalité de la grippe saisonnière. Cette faible mortalité reflète l'existence d'une résistance immunitaire chez les personnes âgées de plus de 60 ans, apparemment due à des homologies de séquences entre le virus pandémique de 2009 et celui de 1918. De nombreux vaccins anti-A (H1N1) 2009 ont été préparés courant 2009, avec ou sans adjuvant et tous ont fait la preuve de leur innocuité et de leur immunogénicité dans des études de Phase I/II chez des volontaires. La campagne de vaccination, lancée en octobre 2009, ne devait cependant connaître qu'un succès mitigé, pour des raisons qui seront exposées. Le porc apparaît une fois de plus comme un réservoir potentiel important de souches de virus grippal pathogènes pour l'homme, ce qui implique de renforcer la surveillance virologique chez cette espèce