Quarkonium production in PbPb collisions at the LHC

I review the recent quarkonium measurements performed at the LHC in PbPb collisions at $\sqrt{s_{NN}}=2.76$ TeV.Comment: 4 pages, 4 figures, to appear in the proceedings of the XLI International Symposium on Multiparticle Dynamics (ISMD), Japan, September 201

Matching frictions and the divide of schooling investment between general and specific skills

This paper examines the impact of labor market frictions and institutions on the divide of schooling investment between general and specific skills. We offer a simple matching model of unemployment in which individuals determine the scope and intensity of their skills. In partial equilibrium, we show that the severity of market frictions distorts the schooling allocation towards more general skills. Then, we endogenize job creation and argue that changes in labor market institutions may well originate a non-monotonous relationship between unemployment and the divide of skills between specific and general human capital. We also investigate more carefully the impacts of unemployment compensation, minimum wage and firing costs. We suggest that unemployment compensation has an ambiguous impact on the skill divide, while minimum wage and firing costs are detrimental to general skill acquisition.Matching frictions; education; general and specific skills; labour market institutions

The man/machine interface in information retrieval: Providing access to the casual user

This study is concerned with the difficulties encountered by casual users wishing to employ Information Storage and Retrieval Systems. A casual user is defined as a professional who has neither time nor desire to pursue in depth the study of the numerous and varied retrieval systems. His needs for on-line search are only occasional, and not limited to any particular system. The paper takes a close look at the state of the art of research concerned with aiding casual users of Information Storage and Retrieval Systems. Current experiments such as LEXIS, CONIT, IIDA, CITE, and CCL are presented and discussed. Comments and proposals are offered, specifically in the areas of training, learning and cost as experienced by the casual user. An extensive bibliography of recent works on the subject follows the text

Lidar detection of metallic species at the mesopause level

The measurement alkali species present in the atomic form at the mesopause level has been performed by lidar for more than ten years. Atomic and ionic calcium density profiles are obtained for 3 years by the same technique in the visible range, at 423 nm for atomic calcium, and 393 nm for ionic calcium Ca(+). The experimental set-up and the preliminary results have been presented elsewhere. The 423 nm wavelength is directly obtained by the emission of a dye laser pumped by the third harmonic of a Nd-YAG laser. For the generation of the 393 nm wavelength, frequency mixing was used: the emission at 624 nm of a dye laser pumped by the 2nd harmonic of a Nd-Yag laser is mixed with the fundamental infrared emission (remaining after frequency doubling), in a non-linear KDP crystal, which gives the 393 nm emission. The behavior of the two atomic species, calcium and sodium, which are in the same altitude range are compared. For 45% of the observations, no ionic calcium was detected: the ionic calcium abundance was thus below the detection threshold. Contrasting with the density profiles of the atomic species, sodium and calcium, the ionic calcium profile present important variations on small time scales. The main characteristics of theatomic and ionic calcium behaviors that can be deduced from the measurements made are given

J/ψJ/\psi production and nuclear effects for d+Au and p+p collisions in PHENIX

PHENIX has measured $J/\psi$ production at backward, central and forward rapidities both in p+p and d+Au collisions at $\sqrt{s_{NN}}=200$ GeV during the third run of the RHIC collider. From the p+p collisions, we measure the total J/$\psi$ cross section. From the d+Au collisions, we compute the nuclear modification factor versus transverse momentum, rapidity and centrality. All results presented here are preliminary.Comment: 4 pages, 4 figure

A microfoundation for adaptability returns to schooling and technological complexity

In a frictional environment, technological complexity creates adaptability returns to schooling. This paper provides microfoundations to such an argument, and revisits the impacts of worker heterogeneity and risk aversion. In our model, firms and workers are located on a knowledge space. Education widens the measure of the knowledge subset that the worker embodies, while technological complexity expands the measure of the knowledge subset that is required to operate on the job. We find uncertainty with regard to the type of the future partner motivates schooling, while it inhibits technological complexity. When workers differ in scholastic ability, the welfare of a given group increases with the proportion of workers of this group. Finally, risk aversion motivates a precautionary demand for education, which in turn creates income risk through firms' technological choices.Education; Multi-dimensional skills; Frictions; Heterogeneity; Risk aversion