7,770 research outputs found

    Public sector and business sector earnings: a comparison

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    We compare public sector wages with private firm ones in 2000, without taking into account for work intensity, job security, advantages&The comparison is made in controlling for age, sex, qualification and residence. We find evidence that public sector provides higher wages to women, to unskilled or persons with low degrees, and in the provinces. Women get higher wages in public sector, except those with high degrees in Paris. Men with high degrees get higher wages in firms, the difference is larger in Paris in comparison with the provinces. Wages dispersion is larger in private firms. For the last ten years, relative situation of public sector employees has been improved from 7 to 11 points.wages, public sector

    Decreasing participation rates for old and young people in France

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    Today, working in the industrialized countries is mainly a matter of middle-aged people (25 to 54 year old). This is particularly true in France where the participation rate for the less than 25 year old people is the smallest one in OECD countries and that for men older than 54 one of the smallest. For the last thirty years, the participation rate of the youngest and oldest working people has been significantly decreasing, apart that of old women due to the increasing trending female participation rate. To illustrate the causes of these changes, we model from a descriptive point of view male and female participation rates for the following age classes: 15 to 19, 20 to 24, 55 to 59 and 60 to 64. Modelling old people participation rate allows us to illustrate the importance of political measures used over the last thirty years to deal with unemployment, in particular the development of early retirement programs and the decrease of the retirement age. Modelling young people participation rate does not give a leading part to a particular cause among the various ones we consider (development of apprenticeship, increasing number of students passing the baccalauréat, population structure, unemployment rate&). In both situations, we measure only weak, if any, response of participation rates to short-term unemployment rate changes.participation rate, unemployment, early retirement programs, apprenticeship, logistic trend

    Field theoretic calculation of scalar turbulence

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    The cascade rate of passive scalar and Bachelor's constant in scalar turbulence are calculated using the flux formula. This calculation is done to first order in perturbation series. Batchelor's constant in three dimension is found to be approximately 1.25. In higher dimension, the constant increases as d1/3d^{1/3}.Comment: RevTex4, publ. in Int. J. Mod. Phy. B, v.15, p.3419, 200

    Multi-locus phylogeny of Pleosporales: a taxonomic, ecological and evolutionary re-evaluation

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    Five loci, nucSSU, nucLSU rDNA, TEF1, RPB1 and RPB2, are used for analysing 129 pleosporalean taxa representing 59 genera and 15 families in the current classification of Pleosporales. The suborder Pleosporineae is emended to include four families, viz. Didymellaceae, Leptosphaeriaceae, Phaeosphaeriaceae and Pleosporaceae. In addition, two new families are introduced, i.e. Amniculicolaceae and Lentitheciaceae. Pleomassariaceae is treated as a synonym of Melanommataceae, and new circumscriptions of Lophiostomataceae s. str, Massarinaceae and Lophiotrema are proposed. Familial positions of Entodesmium and Setomelanomma in Phaeosphaeriaceae, Neophaeosphaeria in Leptosphaeriaceae, Leptosphaerulina, Macroventuria and Platychora in Didymellaceae, Pleomassaria in Melanommataceae and Bimuria, Didymocrea, Karstenula and Paraphaeosphaeria in Montagnulaceae are clarified. Both ecological and morphological characters show varying degrees of phylogenetic significance. Pleosporales is most likely derived from a saprobic ancestor with fissitunicate asci containing conspicuous ocular chambers and apical rings. Nutritional shifts in Pleosporales likely occured from saprotrophic to hemibiotrophic or biotrophic

    Fourfold oscillations and anomalous magnetic irreversibility of magnetoresistance in the non-metallic regime of Pr1.85Ce0.15CuO4

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    Using magnetoresistance measurements as a function of applied magnetic field and its direction of application, we present sharp angular-dependent magnetoresistance oscillations for the electron-doped cuprates in their low-temperature non-metallic regime. The presence of irreversibility in the magnetoresistance measurements and the related strong anisotropy of the field dependence for different in-plane magnetic field orientations indicate that magnetic domains play an important role for the determination of electronic properties. These domains are likely related to the stripe phase reported previously in hole-doped cuprates.Comment: 11 pages, 5 figure

    Low-temperature phonon thermal conductivity of cuprate single crystals

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    The effect of sample size and surface roughness on the phonon thermal conductivity κp\kappa_p of Nd2_2CuO4_4 single crystals was studied down to 50 mK. At 0.5 K, κp\kappa_p is proportional to A\sqrt{A}, where AA is the cross-sectional area of the sample. This demonstrates that κp\kappa_p is dominated by boundary scattering below 0.5 K or so. However, the expected T3T^3 dependence of κp\kappa_p is not observed down to 50 mK. Upon roughing the surfaces, the T3T^3 dependence is restored, showing that departures from T3T^3 are due to specular reflection of phonons off the mirror-like sample surfaces. We propose an empirical power law fit, to κp∼Tα\kappa_p \sim T^{\alpha} (where α<3\alpha < 3) in cuprate single crystals. Using this method, we show that recent thermal conductivity studies of Zn doping in YBa2_2Cu3_3Oy_y re-affirm the universal heat conductivity of d-wave quasiparticles at T→0T \to 0.Comment: 4 pages, 4 figure

    Calculation of renormalized viscosity and resistivity in magnetohydrodynamic turbulence

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    A self-consistent renormalization (RG) scheme has been applied to nonhelical magnetohydrodynamic turbulence with normalized cross helicity σc=0\sigma_c =0 and σc→1\sigma_c \to 1. Kolmogorov's 5/3 powerlaw is assumed in order to compute the renormalized parameters. It has been shown that the RG fixed point is stable for d≥dc≈2.2d \ge d_c \approx 2.2. The renormalized viscosity ν∗\nu^* and resistivity η∗\eta^* have been calculated, and they are found to be positive for all parameter regimes. For σc=0\sigma_c=0 and large Alfv\'{e}n ratio (ratio of kinetic and magnetic energies) rAr_A, ν∗=0.36\nu^*=0.36 and η∗=0.85\eta^*=0.85. As rAr_A is decreased, ν∗\nu^* increases and η∗\eta^* decreases, untill rA≈0.25r_A \approx 0.25 where both ν∗\nu^* and η∗\eta^* are approximately zero. For large dd, both ν∗\nu^* and η∗\eta^* vary as d−1/2d^{-1/2}. The renormalized parameters for the case σc→1\sigma_c \to 1 are also reported.Comment: 19 pages REVTEX, 3 ps files (Phys. Plasmas, v8, 3945, 2001

    Metal-to-Insulator Crossover in the Low-Temperature Normal State of Bi_{2}Sr_{2-x}La_{x}CuO_{6+\delta}

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    We measure the normal-state in-plane resistivity of La-doped Bi-2201 single crystals at low temperatures by suppressing superconductivity with 60-T pulsed magnetic fields. With decreasing hole doping, we observe a crossover from a metallic to insulating behavior in the low-temperature normal state. This crossover is estimated to occur near 1/8 doping, well inside the underdoped regime, and not at optimum doping as reported for other cuprates. The insulating regime is marked by a logarithmic temperature dependence of the resistivity over two decades of temperature, suggesting that a peculiar charge localization is common to the cuprates.Comment: 4 pages, 5 figures, accepted for publication in PR

    A Knowledge Discovery Framework for Learning Task Models from User Interactions in Intelligent Tutoring Systems

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    Domain experts should provide relevant domain knowledge to an Intelligent Tutoring System (ITS) so that it can guide a learner during problemsolving learning activities. However, for many ill-defined domains, the domain knowledge is hard to define explicitly. In previous works, we showed how sequential pattern mining can be used to extract a partial problem space from logged user interactions, and how it can support tutoring services during problem-solving exercises. This article describes an extension of this approach to extract a problem space that is richer and more adapted for supporting tutoring services. We combined sequential pattern mining with (1) dimensional pattern mining (2) time intervals, (3) the automatic clustering of valued actions and (4) closed sequences mining. Some tutoring services have been implemented and an experiment has been conducted in a tutoring system.Comment: Proceedings of the 7th Mexican International Conference on Artificial Intelligence (MICAI 2008), Springer, pp. 765-77
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