National Origin Differences in Wages and Hierarchical Positions - Evidence on French Full-Time Male Workers from a matched Employer-Employee Dataset

This paper estimates the differences in wages and hierarchical positions that can be attributed to national origin in France. Our data come from a matched employer-employee wage survey performed in 2002. The business survey provides very reliable wage data which are matched to many individual-level variables collected in a household survey. The sample of male full-time workers is decomposed into three sub-samples according to the parents' birthplace (France, North Africa and Southern Europe). The large number of executives in the sample allows us to perform a switching regression model of wage determination and occupational employment. We adapt and extend existing decomposition methods to this framework: while usual methods only take care of selection issues, we develop here a methodology which also properly takes into account composition effects due to differences in hierarchical positions when comparing mean wage gaps. Moreover the method we use only requires model estimation on the reference population and therefore yields more precise results when the sample size of the potentially discriminated group is small. Our results show no wage discrimination but a certain degree of occupational segregation yielding composition effects. Moreover, differences in the returns to some of the individual characteristics including higher diplomas might reveal mechanisms of statistical discrimination on the labor market.immigration, discrimination, wage gap, France

Equilibrium Low Temperature Heat Capacity of the Spin Density Wave compound (TMTTF)2 Br: effect of a Magnetic Field

We have investigated the effect of the magnetic field (B) on the very low-temperature equilibrium heat capacity ceq of the quasi-1 D organic compound (TMTTF)2Br, characterized by a commensurate Spin Density Wave (SDW) ground state. Below 1K, ceq is dominated by a Schottky-like contribution, very sensitive to the experimental time scale, a property that we have previously measured in numerous DW compounds. Under applied field (in the range 0.2- 7 T), the equilibrium dynamics, and hence ceq extracted from the time constant, increases enormously. For B = 2-3 T, ceq varies like B2, in agreement with a magnetic Zeeman coupling. Another specific property, common to other Charge/Spin density wave (DW) compounds, is the occurrence of metastable branches in ceq, induced at very low temperature by the field exceeding a critical value. These effects are discussed within a generalization to SDWs in a magnetic field of the available Larkin-Ovchinnikov local model of strong pinning. A limitation of the model when compared to experiments is pointed out.Comment: 10 pages, 11 figure

Predicting the Date of Bud Burst in Grapevines

It was possible to forecast the date of bud burst under South African winter temperatures (Region III) using the Pouget-formulae and principles, and to establish a scale of bud burst for cultivars grown in South Africa. The sum of daily temperature effects was higher under the warmer South African conditions which resulted in changes in the formulae for determining the daily effect of temperature and the cultivar coefficient on the bud burst date. Highly significant linear relationships were, however, obtained and it was possible to predict the date of bud burst fairly accurately

A New Scenario on the Metal-Insulator Transition in VO2

The metal-insulator transition in VO2 was investigated using the three-band Hubbard model, in which the degeneracy of the 3d orbitals, the on-site Coulomb and exchange interactions, and the effects of lattice distortion were considered. A new scenario on the phase transition is proposed, where the increase in energy level separation among the t_2g orbitals caused by the lattice distortion triggers an abrupt change in the electronic configuration in doubly occupied sites from an S=1 Hund's coupling state to a spin S=0 state with much larger energy, and this strongly suppresses the charge fluctuation. Although the material is expected to be a Mott-Hubbard insulator in the insulating phase, the metal-to-insulator transition is not caused by an increase in relative strength of the Coulomb interaction against the electron hopping as in the usual Mott transition, but by the level splitting among the t_2g orbitals against the on-site exchange interaction. The metal-insulator transition in Ti2O3 can also be explained by the same scenario. Such a large change in the 3d orbital occupation at the phase transition can be detected by linear dichroic V 2p x-ray absorption measurements.Comment: 5 pages, 5 figures, to be published in J. Phys. Soc. Jpn. Vol. 72 No. 1

Considérations générales sur le rythme végétatif et la dormance des bourgeons de la Vigne

La variation de la vitesse de débourrement des bourgeons en fonction de la température a été établie durant le cycle végétatif annuel pour des variétés de précocité de débourrement différente. La vitesse de débourrement d'une variété précoce est toujours supérieure à celle d'une variété tardive, quelles que soient l'époque et la température. De 20 à 35°C le débourrement est toujours possible chez les variétés précoces dont la dormance des bourgeons ne se manifeste que par une diminution momentanée de la vitesse de débourrement. Par contre, les variétés tardives présentent une vitesse nulle ou très faible quand les bourgeons sont en dormance. Le cycle végétatif annuel des bourgeons a été subdivisé en cinq phases: phase de pré-dormance, phase d'entrée en dormance, phase de dormance, phase de levée de dormance, phase de post-dormance, L'entrée en dormance des variétés tardives se produit plus tôt que celle des variétés précoces. Mais ces dernières, qui exigent des températures moins basses, subissent la levée de dormance avant les variétés tardives.Le phénomène de levée de dormance est réversible quand les températures dépassent un seuil, plus élevé pour les variétés précoces que pour les tardives (13°C pour Perle de Csaba, 8°C pour Ugni blanc). La dormance des bourgeons est levée quand leur état physiologique a atteint un certain niveau d'évolution, appelé s e u i l d'irréversibilité.Deux processus physiologiques distincts se déroulent dans les bourgeons durant les phases de dormance et de levée de dormance:P r o c e s s u s : A d a p t a t i o n  a u x  b a s s e s  t e m p é r a t u r e s . Sous l'action des températures décroissantes de l'automne, les bourgeons s'adaptent progressivement à subir l 'action des températures basses qui lèvent leur dormance. Ils deviennent en même temps aptes à débourrer plus rapidement, quelles que soient les températures. Des hypothèses sont formulées pour expliquer cette adaptation.P r o c e s s u s : L e v é e  d e  d o r m a n c e . Ce processus, qui peut être décienché naturellement par les températures basses inférieures à un seuil, ou artificiellement par des agents physiques ou chimiques (anaérobiose, substances inhibitrices de la respiration), permet aux bourgeons d'atteindre un état physiologique qui rend le débourrement homogène et en augmente la vitesse. Des réactions fermentaires induites par les inhibiteurs de la respiration constituent une condition suffisante pour la réalisation de ce processus.Le mécanisme physiologique de l'entrée en dormance et de la levée de dormance, n'est pas encore connu avec exactitude.General considerations regarding vegetative rythm and bud dormancy in the vineThe variation of the rate of bud burst as a function of temperature has been evaluated throughout the annual vegetation cycle for varieties differing in regard to their earliness of bud burst. The rate of bud burst of an early variety was found to be always greater than that of a late variety. In the range 20°C to 35°C, bud burst is always possible in early varieties whose bud dormancy is reduced to a temporary decrease in the rate of bud burst. On the other hand, late varieties have a zero or very low rate of bud burst during bud dormancy.We have divided the annual vegetation cycle of the buds into five phases: predormancy, going-into-dormancy, dormancy, dormancy-breaking, post-dormancy. Going-into-dormancy occurs earlier in late varieties as compared with early ones. These, however, undergo the breaking of dormancy earlier than the late ones, because they do not require as high a temperature. Dormancy-breaking is a reversible process, if temperature rises above a threshold which is higher for early varieties than for late ones before it is completed (13°C for P e r l e  d e  C s a b a), (8°C for U g n i  b l a n c ). Bud dormancy is broken once the physiological state of the bud has reached a given level of evolution, which we call irreversibility threshold.Two different physiological processes occur in the buds during the course of the dormancy and dormancy-breaking phases:A d a p t a t i o n  t o  l o w  t e m p e r a t u r e s : As the temperature decreases in the course of autumn, the buds adapt themselves progressively to undergo the action of low temperatures which will eventually break their dormancy. At the same time, they are becoming able to burst at a faster rate whatever the temperature. Hypotheses are proposed that account for this adaptation.B re a k i n g - d o r m a n c y : This process, which can be triggered naturally by temperature lower than a threshold, or artificially, by physical or chemical agents (anaerobiosis, respiration inhibitors) brings the buds to a physiological state in which bud burst is homogeneous, and occurs at an increasing rate. Fermentative reactions induced by the respiration inhibitors are a sufficient condition for this process to occur.The exact nature of the physiological mechanism of going-into-dormancy and of dormancy-breaking, however, remains unknown

Méthode d'appréciation de l'évolution physiologique des bourgeons pendant la phase de pré-débourrement: Application à l'étude comparée du débourrement de la vigne

L'étude du débourrement de bourgeons latents ayant subi un traitement préalable de levée de dormance (immersion dans l'eau à 30° C pendant 48 heures) a permis de montrer que la vitesse ,de débourrement varie en fonction de la température suivant une loi de nature logarithmique entre 5 et 25° C. Chaque cépage est caractérisé par des constantes expérimentales qui traduisent s,a réaction à la température et par ,suite sa précocité de délbourrement.Dans les conditions naturelles, chaque température exerce sur les bourgeons une action d'autant plus forte que le cépage est plus précoce. La somme des actions journalières de la température, calculée depuis une ,date d'origine jusqu'au débourrement, s'est révélée constante chaque année, dans un milieu et pour un cépage donné. Les études ont porté sur quatre cépages {Perle de Csaba, Tra.miner, Merlau, Ugni blanc) pendant 6 années.L'évolution physiologique comparée ,des bourgeons au cours de la phase de prédébourrement peut être appréciée grâce à cette méthode. Il est ainsi possible de prévoir, dans une certaine mesure, La date approx1mative du débourrement en se basant sur l'évolution de la somme des actions journalières de la température pour chaque cépage

Essai d'appréciation de l'intensité de la dormance chez quelques variétés et espèces de vigne

Des bourgeons latents de différentes espèces et variétés de Vigne, prélevés pen-dant la phase de dormance, ont subi un traitement de levée de dormance par la chaleur (eau, 30° C) avant d'être mis dans des conditions favorables au débourrement. L'observation des durées de débourrement (DD 50) montre que les espèces et variétés précoces exigent une durée de traitement de levée de dormance plus courte que les tardives. La précocité de débourrement semble donc liée aux exigences thermiques mais ces résultats ne permettent pas d'affirmer qu'elle est en relation avec l'intensité de la dormance

Depressed mood in a cohort of elderly medical inpatients: Prevalence, clinical correlates and recognition rate

The objectives of this prospective cohort study were to 1) determine the prevalence of depressed mood, 2) identify the characteristics associated with it, and 3) evaluate the recognition rate of depressed mood by clinicians. The study population was a cohort of 401 elderly patients, aged 75 years and older, admitted to the internal medicine service of a tertiary care academic medical center in Western Switzerland over six months. We excluded patients with severe cognitive impairment, terminal disease or those living in a nursing home. Data on demographics, medical, physical, social and mental status were collected upon admission. Presence of depressed mood was defined as a score ≥ 6 on the Geriatric Depression Scale (GDS), short form (15-item). An independent re-viewer performed a discharge summary abstraction to assess recognition rate. Subjects' mean age was 82.4 years, 60.9% were women. Overall, 90 patients (22.4%) had an abnormal GDS score (≥6). Compared to those without a depressed mood, these subjects were (all p<0.05) older (83.5 vs 82.0 years), more frequently living alone (66.7 vs 55.0%), dependent in both basic activities of daily living (BADL) and instrumental ADL (48.9 vs 36.0%, and 91.1 vs 84.9%, respectively), and cognitively impaired (47.8 vs 27.7% with MMSE score<24). In addition, they had more comorbidities (Charlson index 1.6 vs 1.2). In multivariate analysis, an independent association remains for subjects living alone (OR 1.8, 95%CI 1.1-3.0), with cognitive impairment (OR 1.9, 95%CI 1.1-3.2), and comorbidities (OR 1.3 per point, 95%CI 1.1-1.5). Detection rate during the index hospitalization was only 16.7% (15/90). In conclusion, depressed mood was frequent but rarely detected in this population. These findings emphasize the need to improve screening efforts, and to develop additional strategies such as using a pre-screening question to enhance clinical recognitio

Self-organization of charge under pressure in the organic conductor (TMTSF)2ReO4

(TMTSF)2ReO4 presents a phase coexistence between two anion orderings defined by their wave vectors q_2=(1/2,1/2,1/2) and q_3=(0,1/2,1/2) in a wide range of pressure (8-11kbar) and temperature. From the determination of the anisotropy of the conductivity and the superconducting transitions in this regime we were able to extract the texture which results from a self-organization of the orientations of the ReO4 anions in the sample. At the lowest pressures, the metallic parts, related to the q_3 order, form droplets elongated along the a-axis embedded in the semiconducting matrix associated with the q_2 order. Above 10kbar, filaments along the a-axis extend from one end of the sample to the other nearly up to the end of the coexistence regime. A mapping of the system into an anisotropic Ising lattice is satisfactory to analyze the data. satisfactory to analyze the data.Comment: 7 pages, 3 figures, EPL forma

Modulation of charge-density waves by superlattice structures

We discuss the interplay between electronic correlations and an underlying superlattice structure in determining the period of charge density waves (CDW's), by considering a one-dimensional Hubbard model with a repeated (non-random) pattern of repulsive (U>0) and free (U=0) sites. Density matrix renormalization group diagonalization of finite systems (up to 120 sites) is used to calculate the charge-density correlation function and structure factor in the ground state. The modulation period can still be predicted through effective Fermi wavevectors, k_F*, and densities, and we have found that it is much more sensitive to electron (or hole) doping, both because of the narrow range of densities needed to go from q*=0 to \pi, but also due to sharp 2k_F*-4k_F* transitions; these features render CDW's more versatile for actual applications in heterostructures than in homogeneous systems.Comment: 4 pages, 5 figures, to appear in Phys Rev