Ecological Opportunity In Adaptive Radiation Of Galapagos Endemic Land Snails

The classic evolutionary hypothesis of ecological opportunity proposes that both heterogeneity of resources and freedom from enemies promote phenotypic divergence as a response to increased niche availability. Although phenotypic divergence and speciation have often been inferred to be the primary consequences of the release from competition or predation that accompanies a shift to a new adaptive zone, increased phenotypic variation within species is expected to represent the first stage resulting from such a shift. Using measures of intraspecific morphological variation of 30 species of Galapagos endemic land snails in a phylogenetically controlled framework, we show that the number of local congeners and the number of local plant species are associated with lower and higher intraspecific phenotypic variation, respectively. In this clade, ecological opportunity thus explicitly links the role of competition from congeners and the heterogeneity of resources to the extent of intraspecific phenotypic divergence as adaptive radiation proceeds.Integrative Biolog

Is Workers' Compensation Disguised Unemployment Insurance?

This paper examines how yhe Workers' Compensation (WC) and the Unemployment Insurance (UI) programs interact to influence the duration of claims due to workplace accidents. We use longitudinal WC administrative micro-data on more than 30,000 workers in the Quebec construction industry for the period 1976-1986. Our results show that a reduction in the UI wage replacement ratio is associated with an increase in the duration of claims due to serve accidents that are difficult to diagnose (this category includes severe back-related problems). Also, an increase in the WC replacement ratio leads to an increase in the average duration of claims due to minor accidents that are difficult to diagnose (this category includes minor low-back injuries). Moreover, there seems to be an important seasonal effect in the duration of claims; i.e., the average duration of spells on WC is estimated to be 21.2% higher when an accident occurs in December rather than in July. Ce texte examine comment l'assurance contre les lésions professionnelles (ALP) et l'assurance-chômage (AC) interagissent pour influencer la durée des réclamations pour lésions professionnelles. Nous utilisons des micro-données administratives longitudinales couvrant plus de 30 000 travailleurs du secteur de la construction pour la période 1976-1986. Nos résultats montrent qu'une réduction du taux de remplacement salarial de l'assurance-chômage est associée à une augmentation de la durée des accidents majeurs difficiles à diagnostiquer (cette catégorie inclut les maux de dos majeurs). De plus, un accroissement du taux de remplacement salarial de l'ALP entraîne un accroissement de la durée des accidents mineurs difficiles à diagnostiquer (cette catégorie inclut les lombalgies). Enfin, il semble y avoir un effet saisonnier lié à la durée des périodes d'indemnisation est plus élevée de 21.2% lorsqu'un accident survient en1101 plutôt qu'en0701.duration, worplace accidents, construction, worker's compensation, unemployment insurance, hazard, durée, accidents du travail, lésions professionnelles, assurance-chômage, construction, hazard

Galvanic coupling between copper and aluminium in a thin-layer cell

The Al/Cu coupling was investigated in a thin-layer cell formed by a large Cu electrode and an Al microelectrode embedded in an insulator placed above the Cu electrode. By using a scanning electrochemical microscope (SECM) the thickness of the thin layer was perfectly controlledwith a precision in the micrometer range. A copper deposit on an electrochemical quartz crystal microbalance (EQCM) was also used as SECM substrate to quantify the copper dissolution rate. It was shown that such an experimental set-up allows to mimic the galvanic corrosion of intermetallic particles embedded in the aluminium matrix of the 2XXX series aluminium alloys. The combination of the SECM and the EQCM permitted the evaluation of the corrosion rate of copper at the corrosion potential of the 2024 Al alloy, whereas cyclic voltammetry performed on the SECM tip indicated the enrichment in Cu2+ ions in the thin electrolyte layer

A Synthesis of Bipedal Locomotion in Human and Robots

This report is the result of a joint reflection carried out by researchers from automatic control and neuroscience fields, both trying to answer a same question: what are the functional basis of bipedal locomotion and how to control them? The originality of this work is to put in parallel two synthesis of how the problem of biped displacements is solved in robotics in one hand and in nature in the other hand. We believe that the key e lements explaining the performances in adaptability and reactivity of human could help roboticians to find some issues for the design of automatic control schemes. Similarly, the theoretical framework of biped robotics could help neuroscientists to formulate concepts and models

A Synthesis of Bipedal Locomotion in Human and Robots

This report is the result of a joint reflection carried out by researchers from automatic control and neuroscience fields, both trying to answer a same question: what are the functional basis of bipedal locomotion and how to control them? The originality of this work is to put in parallel two synthesis of how the problem of biped displacements is solved in robotics in one hand and in nature in the other hand. We believe that the key e lements explaining the performances in adaptability and reactivity of human could help roboticians to find some issues for the design of automatic control schemes. Similarly, the theoretical framework of biped robotics could help neuroscientists to formulate concepts and models

Localized approach to galvanic coupling in an aluminum–magnesium system

The corrosion behavior of a pure aluminum/pure magnesium couple in a weakly conductive sodium sulfate solution was investigated. Potential and current distributions on the surface of the model couple at the beginning of immersion were obtained by solving the Laplace equation using a finite element method algorithm. Magnesium acted as the anode of the system while oxygen and water were reduced on aluminum. Calculations predicted a large current peak at the Al/Mg interface related to a local increase in both Mg dissolution and oxygen and water reduction on aluminum, leading to a local pH increase. Optical and scanning electron microscope observations confirmed the strong dissolution of magnesium concomitantly with depassivation of aluminum at the Al/Mg interface. Local electrochemical impedance spectroscopy showed the detrimental effects of the galvanic coupling both on aluminum and magnesium

Galvanic Coupling Between Pure Copper and Pure Aluminum Experimental Approach and Mathematical Model

The corrosion behavior of a pure aluminum/pure copper couple in a weakly conductive sulfate solution was investigated. Potential and current distributions on the surface of the model couple at the beginning of immersion were obtained by solving the Laplace equation using a finite element method (FEM) algorithm. The potential distribution predicted by the calculations was checked using a Ag/AgCl microreference electrode. A good agreement was found between experimental and theoretical results. It was shown that the reaction occurring at the copper electrode was oxygen reduction, while aluminum remote from the Al/Cu interface remained in the passive state. Moreover, calculations predicted a large cathodic current, related to an increase in oxygen reduction, restricted to copper at the Al/Cu interface. This led to a local pH increase reaching values higher than 9, allowing the dissolution of aluminum to occur close to the interface. Combining these data with optical and scanning electron microscope observations after 24 h of immersion in the sodium sulfate solution allowed a three-step mechanism to be proposed to explain the corrosion damage, and particularly the presence of a copper deposit on the aluminum surface, some distance from the Al/Cu interface, a phenomenon currently observed in commercial copper-rich aluminum alloys

Identification of intermetallic precipitates formed during re-solidification of brazed aluminium alloys

This study shows that Fe and Mn bearing phases in Al–Si alloys containing a low level of Fe and Mn are essentially cubic greek small letter alpha-Al(Fe, Mn)Si with Im3 space group and δ-AlFeSi which is observed with both tetragonal and orthorhombic structures. As this latter phase is not expected to form according to the ternary Al–Fe–Si phase diagram, the present results suggest that it is stabilized in the quaternary Al–Fe–Mn–Si system with respect to other phases such as β-Al4FeSi

L'évaluation des effets - emploi des politiques publiques régionales en France : Vers un élargissement méthodologique

Cette recherche méthodologique vise à proposer un cadre d'évaluation élargissant le champ de l'évaluation des politiques régionales et des fonds structurels au-delà des seuls effets quantitatifs sur l'emploi. Ce cadre intègre les apports des analyses en termes de " qualité de l'emploi " développées à l'échelon international, ainsi que ceux des théories des Marchés Transitionnels du Travail, et propose une batterie d'indicateurs d'évaluation enrichie de considérations sur les trajectoires individuelles, l'accès à la formation, l'égalité hommesfemmes, les possibilités de conciliation entre vie familiale et vie professionnelle, les conditions de travail

Hautes Chaumes du Forez, suivi scientifique, évolution du couvert végétal entre 1998 et 2005

rapport inédit, 36pL'étude de deux images SPOT5 permet de mesurer les évolutions de la végétation entre 1998 et 2005.Les principaux milieux, landes, pelouses et forêts sont analysées, et les substitutions observées mise en relation avec la dynamique naturelle et les pratiques de gestion de cet espace