Antenna technology for advanced mobile communication systems

The onboard antenna front end is the key subsystem conditioning configuration and performance of mobile communication satellites. The objectives of this paper are to demonstrate this key role and to review L-band satellite antenna technology for earth coverage and regional applications. Multibeam arrays are first discussed, then unfurlable and inflatable reflector antennas are described. These technologies are now qualified in Europe for future mobile systems, for which the optimum choice of antenna technology has been found to be the key to efficient use of spectrum and power resources

Labor force participation by the elderly and employment of the young: The case of France

One of the justifications provided for early retirement policies in developed countries is the idea that such policies can facilitate access to the labor market for younger people and help lower global unemployment. But many questions remain on the true effect on young workers of these policies. The objective of the present paper is to study the long term relationship between labor force participation of the old and unemployment of the young in France since the beginning of the 1970s. Establishing causal relationship of the reduction of labor force participation of the old on employment prospect of the young is a challenging work. Evidence of the correlation between youth labor market outcomes and older worker's labor force participation plead more in favor of a positive association between younger and older workers' employment. An increase in the older workers' participation is indeed correlated with an increase in the employment rate of young workers and a decrease in their unemployment rate. Even controlling for the economic cycle, this positive association remains - albeit less robustly. These correlations, based on times series, are not however evidence of causal relationship between younger and older workers' employment. We then use an index summarizing the intensity of policies aiming at removing older workers from the labor market, based on Social Security wealth. The effect of the wealth index on youth labor market outcomes is always significant, whatever the set of the control variables we use and with a similar size and the same sign. The coefficient is negative for both the unemployment and employment of youth, with or without controlling for school attendance. In France policies aiming at removing older workers from the labor market have been prompted by increase in unemployment. Granger causality tests between youth unemployment and the Wealth index show therefore a significant link in both directions, whereas nothing is significant between youth employment and the Wealth index. Hence if we do not find evidence that reducing labor force participation of the old provide jobs for the young, we cannot exclude altogether that some general and unaccounted cause is hiding its true impact.retirement policies ; labor market participation ; unemployment

Neutron dose and its measurement in proton therapy – Current State of Knowledge

Proton therapy has shown dosimetric advantages over conventional radiation therapy using photons. Although the integral dose for patients treated with proton therapy is low, concerns were raised about late effects like secondary cancer caused by dose depositions far away from the treated area. This is especially true for neutrons and therefore the stray dose contribution from neutrons in proton therapy is still being investigated. The higher biological effectiveness of neutrons compared to photons is the main cause of these concerns. The gold standard in neutron dosimetry is measurements, but performing neutron measurements is challenging. Different approaches have been taken to overcome these difficulties, for instance with newly developed neutron detectors. Monte Carlo simulations is another common technique to assess the dose from secondary neutrons. Measurements and simulations are used to develop analytical models for fast neutron dose estimations. This article tries to summarize the developments in the different aspects of neutron dose in proton therapy since 2017. In general, low neutron doses have been reported, especially in active proton therapy. Although the published biological effectiveness of neutrons relative to photons regarding cancer induction is higher, it is unlikely that the neutron dose has a large impact on the second cancer risk of proton therapy patients

Partis politiques et électorats paysans en Bulgarie et en Roumanie

Après l'effondrement du bloc soviétique, la vie politique a connu des évolutions similaires en Bulgarie et en Roumanie. Dans les deux pays, une formation dirigée par d'anciens communistes reconvertis est parvenue à s'imposer : le Parti socialiste bulgare a exercé le pouvoir en 1991, puis entre 1992 et 1997 ; après avoir gouverné la Roumanie entre 1991 et 1996, le parti de Ion Iliescu est revenu aux affaires en novembre 2000. L'une et l'autre formation ont trouvé leurs principaux soutiens dans l'électorat paysan. Les élections municipales leur ont permis d'obtenir des mandats exécutifs dans la grande majorité des communes rurales. Pour comprendre les fortunes diverses que rencontrent les partis politiques bulgares et roumains dans leurs tentatives d'implantation locale, il est nécessaire d'écarter à la fois les thèses de la désagrégation et de l'imprégnation. Il s'agit de mettre en évidence un “fondu enchaîné” entre le régime communiste et la période présente, tant au niveau macro-institutionnel qu'au niveau micro-institutionnel. En outre, les paysans ne forment pas une masse ductile que les partis politiques pourraient manipuler à leur guise. Ils ne votent pas comme un seul homme pour le responsable de la coopérative ou de la société agricole dans laquelle ils sont engagés

L’implantation rurale des partis politiques en Europe orientale

En Bulgarie et en Roumanie, les relations entre les partis politiques et l’électorat paysan participent de logiques distinctes. Pour caractériser ces logiques, un rapprochement doit être opéré entre les niveaux macroinstitutionnel et microinstitutionnel. Au niveau macroinstitutionnel, il convient d’examiner les modalités selon lesquelles les programmes agraires sont définis et mis en œuvre. Les réformes introduites dans l’agriculture sont largement tributaires des relations agraires instaurées sous le régime communiste : selon que les paysans ont entretenu un rapport harmonieux ou tendu avec le pouvoir, la décollectivisation obéit à des logiques diversifiées. Les variations ainsi relevées s’emboîtent dans le niveau microinstitutionnel. La logique de la décollectivisation conditionne la diffusion des mots d’ordre politiques auprès des paysans. Les programmes agraires sont récupérés par des intermédiaires locaux puis adaptés aux structures locales selon différentes modalités.Rural support for political parties in eastern Europe. – Quite different rationales shape the relations between political parties and farmer voters in Bulgaria and Romania. To describe them, both the macro- and microinstitutional levels must enter into account. At the macro level, the way farm programs have been drawn up and implemented must be examined. Reforms in agriculture depend very much on the “agrarian relations” established under Communism. Depending on whether farmers had tense or harmonious relations with the powers-that-used-to-be, decollectivization on the micro level has followed quite different rationales, which have conditioned the diffusion of political slogans among farmers. Farm programs have been recuperated by local middlemen and then adapted to local structures in various ways