Constraining local UV field geometry at reionization using Milky Way satellites

We present a new semi-analytical model of the population of satellite galaxies of the Milky Way, aimed at estimating the effect of the geometry of reionization at galaxy scale on the properties of the satellites. In this model reionization can be either: (A) externally-driven and uniform, or (B) internally-driven, by the most massive progenitor of the Milky Way. In the latter scenario the propagation of the ionisation front and photon dilution introduce a delay in the photo-evaporation of the outer satellites' gas with respect to the inner satellites. As a consequence, outer satellites experience a longer period of star formation than those in the inner halo. We use simple models to account for star formation, the propagation of the ionisation front, photo-evaporation and observational biases. Both scenarios yield a model satellite population that matches the observed luminosity function and mass-to-light ratios. However, the predicted population for scenario (B) is significantly more extended spatially than for scenario (A), by about 0.3 dex in distance, resulting in a much better match to the observations. The survival of the signature left by the local UV field during reionization on the radial distribution of satellites makes it a promising tool for studying the reionization epoch at galaxy scale in the Milky Way and nearby galaxies resolved in stars with forthcoming large surveys.Comment: Proceedings of the conference "Assembling the puzzle of the Milky Way" held at Le Grand Bornand, 201

New Technologies, Workplace Organisation and the Age Structure of the Workforce: Firm-Level Evidence

This paper investigates the relationships between new technologies, innovative workplace practices and the age structure of the workforce in a sample of French manufacturing firms. We find evidence that the wage bill share of older workers is lower in innovative firms and that the opposite holds for younger workers. This age bias is also evidenced within occupational groups, thus suggesting that skills do not completely protect workers against the labour market consequences of ageing. More detailed analysis of employment inflows and outflows shows that new technologies essentially affect older workers through reduced hiring opportunities, whereas organisational innovations mainly increase their probability of exit. This suggests that some skill obsolescence may be at work in our sample.new work practices, technology, older workers, labour demand

The labour market after age 50: some elements of a Franco-American comparison

This paper examines various supply and demand side aspects of the French labour market for older workers and puts them in perspective by comparing them to the US case. We first consider the supply side incentives (or disincentives) of basic pension schemes for the two countries : for France, we discuss how these incentives have been changed by the 1993 and 2003 pension reforms and we present some projections of the impact of these reforms on labour force participation rates, based on the DESTINIE dynamic microsimulation model. We then discuss, on the demand side, the hypothesis of a wage-productivity gap for older workers which could explain their lower employment rates. Evidence in favor of this hypothesis is not overwhelming. Nevertheless, workers who lose their jobs at older ages probably suffer a large loss of firm-specific and sector-specific human capital. In the US, this does not preclude re-employment, but at the cost of significant drops of wage levels. In France, the collective choice has been made since the 1970s to allow older workers who lose their jobs to completely withdraw from the labour market : these workers have access to preretirement schemes or specific dispositions of unemployment insurance (including an exemption from seeking employment). This system proved difficult to regulate. Due to these difficulties, France has not been able to do more than stabilize the employment rate in the 55-64 age bracket during the 1990s, after 20 years of continuous decline. The key unanswered question is whether it will be possible to increase the employment rate of this age group in the next two decades.Pensions, preretirement, senior workers

An Overview of the Situation of Workers over 50 in the Private Sector

Using exhaustive data covering all private sector and state-owned firms in France, we describe the distribution of workers aged more than 50, across sectors, regions and different size of plants. We also describe trends of evolution of this distribution between 1995 and 2000. These workers are overrepresented in skilled jobs, despite their lower level of initial training. A higher share of these workers among the labour force can also be found in industrial sectors and sectors such as finance, real estate business or post and telecommunications, while services usually face a low share of older workers among the labour force. However the share of older workers in a sectors labour force is a misleading way to interpret firms behaviour toward older workers, since it usually stems from employment trends within this sector rather than crowding-out strategies. The flow of older workers out of employment is actually found to be larger in manufacturing industries than in service industries between 1995 and 2000. We also find evidence that unskilled workers are crowded-out faster than skilled workers for those aged 50 to 54 in manufacturing. Finally, older workers receive higher wages than the average and this wage gap between older workers and younger ones is increasing with qualification. However, it tends to decrease between 1995 and 2000 for workers aged 50 to 54.Older workers; distribution across sectors

Semileptonic Bs ->DsJ(2460)l nu decay in QCD

Using three point QCD sum rules method, the form factors relevant to the semileptonic Bs ->DsJ (2460)l nu decay are calculated. The q2 dependence of these form factors is evaluated and compared with the heavy quark effective theory predictions. The dependence of the asymmetry parameter alpha, characterizing the polarization of DsJ meson, on q2 is studied .The branching ratio of this decay is also estimated and is shown that it can be easily detected at LHC.Comment: 21 pages, 5 figures and 1 Tabl

Offshore Outsourcing and the size of the French Industrial Labor Force

We estimate the amount of job losses in the manufacturing sector in France due to offshore outsourcing. Our estimation is based on exhaustive, micro-level data covering all firms in the manufacturing sector in France from 1995 to 2001. We identify the groups or firms where employment decreases in French units and, at the same time, for which the imports of the good previously produced in France increases. Between 1995 and 2001, 13 500 jobs are lost each year on average in France due to offshore outsourcing in the manufacturing sector. In slightly less than half of the cases, offshore outsourcing is directed towards a low wage country : mainly China, but also North Africa, Eastern Europe, Asia, Brazil. Job losses are more frequent in some sectors, such as clothing, textile, domestic equipment, manufacture of electronic equipments and components. Nonetheless, offshore outsourcing is observed in nearly all sectors.offshore outsourcing, international competition, job loss, industrial organization

Charm Leptonic and Semileptonic Decays

Experimental results for the pseudoscalar decay constants f_{D} and f_{D_s} are reviewed. Semileptonic form factor results from D -> (pseudoscalar) l nu and D -> (vector) l nu decays are also reviewed.Comment: 8 pages, 4 figures, presented at the 11th International Conference on B-Physics at Hadron Machines (BEAUTY 2006) Sept. 25-29, Oxford, England; corrected typo

Pertinence d'une méthode de prédétermination des crues basée sur la simulation stochastique de pluies horaires.

International audienceExtreme events are rarely observed, so their analysis is generally based on observations of more frequent values. The relevance of flood frequency analysis (FFA) method depends on its capability to estimate the frequency of extreme values with reasonable accuracy using extrapolation. A FFA method based on stochastic simulation of flood event is assessed based on its reliability and stability. For such an assessment, different training/testing decompositions are performed for a set of data from more than 1,000 gauging stations. We showed that the method enables relevant "predictive" estimates, e.g. by assigning correct return periods to the record values that are systematically absent in calibration data sets. The model is also highly stable vis-a-vis the sampling. This characteristic is linked to the use of regional statistical rainfall data and a simple rainfall-runoff model that requires calibrating only one parameterLes événements extrêmes sont par nature rarement observés, c'est pourquoi leur estimation est généralement basée sur l'observation de valeurs plus courantes. La pertinence d'une méthode de prédétermination des événements extrêmes dépend donc de sa capacité à raisonnablement extrapoler les distributions de fréquences vers les valeurs extrêmes. Dans cette étude, une méthode de prédétermination de crues basée sur la simulation de scénarios de pluies horaires, est évaluée sur sa capacité à produire des estimations justes et stables. Cette évaluation s'appuie sur différents tests d'échantillonnage sur les périodes de calage et de validation, appliqués sur un jeu de données conséquent (plus de 1000 stations). Nous montrons que la méthode est capable de fournir une estimation pertinente sur les événements extrêmes bien que ceux-ci soit systématiquement ôtés de la période de calage. La méthode montre aussi une grande stabilité face à l'échantillonnage. Cette caractéristique est liée à l'utilisation d'une information statistique régionale sur la pluie et à la simplicité de la modélisation hydrologique paramétrée par un seul paramètre