Rupture conventionnelle, destructions d'emplois et licenciements : une analyse empirique sur données d'entreprises (2006-2009)

D - Microeconomics/D2 - Production and Organizations/D22 - Firm Behavior: Empirical Analysis URL des Documents de travail : http://centredeconomiesorbonne.univ-paris1.fr/bandeau-haut/documents-de-travail/Documents de travail du Centre d'Economie de la Sorbonne 2013.69 - ISSN : 1955-611XIn 2008, a new legal termination of long-term contract (CDI) called "the rupture conventionnelle" was enacted. The aim of this article is first to analyze the impact of this new termination on the employers' fire decisions and then to provide empirical evidence of a substitution between the "rupture conventionnelle" and other terminations. Using two matched firms' datasets, one from workers'movement data (EMMO-DMMO) and another from accounting data (EAE), our database includes a firms' sample over four consecutive years from 2006 to 2009. We use the difference-in-differences method combined with a propensity score matching to control selection bias and thus to create two similar firms' groups: those that used the "rupture conventionnelle" and those not. Our main results indicate that the introduction of the "rupture conventionnelle" in crisis times tends to increase workforce exits and many more job destruction. However, we do not find any evidence of a substitution between the RC and the firing for personal reasons, which have become more expensive and riskier.L'objectif de l'article est d'étudier l'impact de la rupture conventionnelle (RC), nouvelle modalité de rupture du contrat à durée indéterminée (CDI) instituée par la loi en 2008, sur les décisions de destruction d'emplois des entreprises d'une part, et sur l'existence de comportement de substitution avec les autres modalités de rupture du CDI d'autre part. Notre démarche est empirique et s'appuie sur un échantillon d'entreprises obtenu par l'appariement de données sur les mouvements de main-d'oeuvre (EMMO-DMMO) et de données sur les résultats comptables des entreprises (EAE). Nous mobilisons une méthode d'estimation en doubles différences, après un appariement sur score de propension des entreprises n'ayant pas utilisé la RC avec des entreprises l'ayant utilisée. Les principaux résultats de l'analyse économétrique montrent que l'introduction de la RC, dans un contexte de forte crise, a eu tendance à intensifier les sorties de main-d'oeuvre, mais plus encore les destructions d'emplois. En outre, aucun comportement de substitution entre la démission ou le licenciement pour motif personnel et la RC n'est mis en évidence par nos résultats

ASPECTS OF CELLULAR IRON HOMEOSTASIS: NRAMP TRANSPORTER FUNCTION AND ERYPTOSIS

The present study focus attention on \u201cAspects of cellular iron homeostasis: NRAMP transporter function and eryptosis\u201d combining aspects of both basic (first chapter: \u201cIron transporters NRAMP1 and NRAMP2 from Dictyostelium discoideum as a model of cellular iron homeostasis\u201d) and applied physiology (second chapter: \u201cEffects of xenobiotics on the suicidal death of erythrocytes\u201d). Iron plays a central role in a large number of essential cellular functions but it is also potentially toxic being able to generate reactive oxygen species (ROS). SLC11 and SLC40 families are involved in iron transport and play an important role in the maintenance of iron homeostasis. The SLC11 family is comprised of two members, SLC11A1 and SLC11A2. SLC11A1 is expressed in the phagolysosome of macrophages and in the tertiary granules of neutrophils and it contributes to the innate resistance against bacterial infection. SLC11A2 (also known as DMT1) is expressed in the proximal duodenum, immature erythroid cells, brain, placenta and kidney and is a key player in iron metabolism. Intestinal iron absorption is indeed mediated by SLC11A2 at the apical membrane of enterocytes and is followed by basolateral exit via SLC40A1. D. discoideum represents a model for the study of cellular iron homeostasis, showing subcellular localization of iron transporters resembling that of macrophages. The Dictyostelium genome shares with mammals many genes regulating iron homeostasis; in particular, D. discoideum expresses the ortholog of SLC11A1 transporter in phagolysosomes and that of SLC11A2 in the contractile vacuole. To better understand the function of Dictyostelium NRAMP proteins, they were expressed in Xenopus laevis oocytes by cRNA injection and functionally tested by radiochemical techniques and by a novel assay based on metal-induced changes in calcein fluorescence. Radiochemical assays showed that NRAMP1 induced iron transport is proton-dependent and it is inhibited by Mn2+, Cd2+, Co2+, Ni2+, Cu2+ and to a lesser extent by Zn2+. In calcein-injected oocytes expressing NRAMP1 and analyzed using confocal microscopy, Fe2+, Mn2+ and but not Fe3+ or Cu2+ led to fluorescence quenching due to their transport and accumulation into the cytoplasm of the oocytes. Therefore Dictyostelium NRAMP1 is an electrogenic proton-dependent divalent metal ion transporter with a cation selectivity comparable to that of rat DMT1. NRAMP1 colocalizes with V-ATPase in the membrane of phagolysosomes. Thus, it exploits the proton gradient maintained by the V-ATPase to mediate the efflux of iron from the phagolysosomes to the cytosol after bacterial engulfment. Preliminary studies showed that D. discoideum NRAMP2 can transport ferrous iron at neutral pH and it appears independent from proton gradient but dependent on Na+, nevertheless its transport activity is strongly reduced compared with that observed for NRAMP1. The second topic of this PhD thesis is eryptosis, the suicidal death of erythrocytes. Mutations that reduce DMT1 activity in human are associated with a severe defect in erythroid iron utilization and are correlated with several diseases. DMT1 deficiency causes an impaired erythroid differentiation hallmarked by accumulation of immature forms of erythroblast, accelerated death of erythroid precursors and a decreased survival in the erythroid progenitors. Iron deficiency is associated with shortened life span of erythrocytes. The accelerated clearance of erythrocytes can be attributed to excessive hemolysis or induction of programmed cell death of erythrocytes, called eryptosis. Eryptosis is fostered by an increase in cytosolic calcium. Iron deficient erythrocytes when exposed to stress conditions has been demonstrated to activate Ca2+-permeable cation channel allowing Ca2+ entry. Ca2+ entry through this channels leads to activation of a scramblase with subsequent phosphatidylserine exposure and to activation of the Gardos channels leading to KCl loss and cell shrinkage. This study was conducted in order to investigate prospective antitumoral products which are employed against tumor growth in humans, in particular CA4P or Pazopanib, or compounds used in vitro, such as Nocodazole, Terfenadine, Piceatannol, Ceranib-2 and Sclareol, in order to unveil the effects on erythrocytes survival and to clarify the mechanisms and signalling involved in their action. Human erythrocytes drawn from healthy individual were incubated in vitro at a hematocrit of 0.4% in Ringer solution. Where indicated, RBCs were exposed for 48 hours to the drugs at the indicated concentrations. The main hallmarks of eryptosis were investigated by flow cytometry. Phosphatidylserine exposure at the cell surface was estimated from annexin-V-binding, cell volume from forward scatter, [Ca2+]i from Fluo3-fluorescence, reactive oxygen species (ROS) formation from DCF-dependent fluorescence, GSH levels by CMF-dependent fluorescence and ceramide abundance utilizing specific antibodies. Hemoglobin concentration in the supernatant was taken as measure of hemolysis. ATP levels following CA4P treatment were measured using luciferin-luciferase assay kit. For studying the effect of Nocodazole on tubulin in human erythrocytes, TubulinTracker\u2122 Green reagent was used. A 48 hours exposure of human erythrocytes to CA4P, Pazopanib, Nocodazole, Terfenadine, Piceatannol, Ceranib-2 or Sclareol treatment increased the percentage of annexin-V-binding cells. Furthermore, the effect of Sclareol on annexin-V-binding was significantly blunted in the presence of p38 kinase inhibitor skepinone and in the presence of casein kinase 1\u3b1 inhibitor D4476. CA4P and Piceatannol significantly decreased forward scatter. CA4P, Nocodazole, Terfenadine, Ceranib-2 and Sclareol treatment significantly increased Fluo3-fluorescence. CA4P significantly decreased GSH abundance and ATP levels. In addition, Pazopanib, Terfenadine, Ceranib-2 and Sclareol further resulted in significant hemolysis. Pazopanib, Nocodazole and Ceranib-2 significantly increased DCF-fluorescence and ceramide abundance. Nocodazole treatment reduced total tubulin abundance. In conclusion, these xenobiotics trigger eryptosis through different mechanisms

Structural behavior analysis of elastic compensation superstructure for innovative ski production

elaborato sull'analisi di sovrastrutture di compensazione elastica per sci. Modellizzazione di un nuovo prodotto per prototipazione in alluminio e resina. Studio di diverse tipologie e marche di sci al banco Slitech per confronti tra le stesse e per osservare affidabilità e ripetibilità del banco stesso. Studio di una piastra integrale in legno che va a costituire un pezzo unico tra piastra per attacchi e prolunga per aumentare la rigidezza e il carico nella parte centrale della spatolaopenEmbargo per motivi di segretezza e/o di proprietà  dei risultati e/o informazioni sensibil

Pratiques des employeurs en matière de licenciements : une analyse sur données d'entreprises

Classification JEL : D - Microeconomics/D2 - Production and Organizations/D22 - Firm Behavior : Empirical Analysis URL des Documents de travail : http://centredeconomiesorbonne.univ-paris1.fr/bandeau-haut/documents-de-travail/Documents de travail du Centre d'Economie de la Sorbonne 2012.49 - ISSN : 1955-611XThe main purpose of the article is to analyze employers' practices in terms of layoffs over the period 1999-2009. Our empirical approach is based on firm dataset from matching worker movements data (EMMO-DMMO) and accounting data (EAE). We want to identify the factors linking the two types of layoffs (for economic reason and for personal reason). The results of the econometric analysis show a separation between dismissal for personal reason and dismissal for economic reason : on the one hand, the economic indicators have a more systematic influence on dismissal for economic reason ; on the other hand, worker management variables are clearly more associated with the use of dismissal for personnal reason.L'objectif de l'article est d'étudier les pratiques des employeurs en matière de licenciement sur la période 1999-2009. Nous adoptons pour cela une démarche empirique s'appuyant sur un échantillon d'entreprises (environ 10 000) obtenu par l'appariement de données sur les mouvements de main-d'oeuvre (EMMO-DMMO) et de données comptables (EAE). Il s'agit d'identifier les facteurs auxquels sont liées les deux formes de licenciement (économique et personnel). Les résultats de l'analyse économétrique montre une séparation entre licenciement pour motif personnel (LMP) et licenciement pour motif économique (LME) : d'un côté, les variables économiques ont une influence plus systématique sur le LME ; tandis que les variables de gestion de la main-d'oeuvre sont plus nettement associées au recours au LMP

Special issue “metal nanoparticles as catalysts for green applications”

This Special Issue of Processes on “Metal Nanoparticles as Catalysts for Green Applications” collects recent works of researchers on metal nanoparticles as catalysts for green applications [...

La rupture conventionnelle : objectifs officiels versus enjeux implicites

URL des Documents de travail : http://centredeconomiesorbonne.univ-paris1.fr/bandeau-haut/documents-de-travail/Documents de travail du Centre d'Economie de la Sorbonne 2010.101 - ISSN : 1955-611XThe ‘conventional cancelation' is a way for employer and employee to mutually agree for ending the labor contract. Officially, it will permit to raise mutually beneficial agreements and to reduce the judge role. First, what is at stake here is the bargaining capacity of the employee and the nature of his agreement since he is in a relation of subordination. Second, the meaning of the eviction of the judge will be also questioned.La rupture conventionnelle du contrat de travail, alternative au licenciement et à la démission, s'adresse aux ruptures d'initiative commune entre salarié et employeur. Officiellement, elle est censée réduire le contentieux et favoriser les ruptures négociées. Il s'agit ici de questionner les enjeux implicites de ces objectifs officiels et leurs éventuels effets pervers. En effet, en permettant une négociation bilatérale avec un salarié en position de subordination, elle altère sa capacité de négociation et fragilise son libre consentement ; par ailleurs, elle pose la question du sens de la baisse du contentieux observée après de telles ruptures, conséquence d'une réduction de l'espace du contentieux possible plutôt que d'une réduction de la conflictualité

La rupture conventionnelle : objectifs officiels versus enjeux implicites

La rupture conventionnelle du contrat de travail, alternative au licenciement et à la démission, s'adresse aux ruptures d'initiative commune entre salarié et employeur. Officiellement, elle est censée réduire le contentieux et favoriser les ruptures négociées. Il s'agit ici de questionner les enjeux implicites de ces objectifs officiels et leurs éventuels effets pervers. En effet, en permettant une négociation bilatérale avec un salarié en position de subordination, elle altère sa capacité de négociation et fragilise son libre consentement ; par ailleurs, elle pose la question du sens de la baisse du contentieux observée après de telles ruptures, conséquence d'une réduction de l'espace du contentieux possible plutôt que d'une réduction de la conflictualité.Rupture conventionnelle, licenciement, économie du travail, économie du droit.

A review on the efficient catalysts for algae transesterification to biodiesel

The depletion of fossil fuel resources and increasing environmental pollution led to a trend for using alternative, clean, green, and sustainable fuel and energy resources. To attain this aim, using biomass as an alternative resource for diesel production has been a hotspot among researchers. Biodiesel has several advantages, such as being lower toxic and more renewable, and eco-friendlier than diesel from fossil fuel resources. Several edible and non-edible bio-sources were used for the production of biodiesel from the transesterification process. Algal oil as a non-edible source is considered an abundant, low cost and green substrate for biodiesel production. Various factors such as reaction conditions and the type of catalyst affect the biodiesel production process. Different catalytic systems such as basic and acidic homogeneous and heterogeneous catalysts and biocatalysts were introduced for the process in the literature, and each proposed catalyst has its own advantages and disadvantages. For instance, in spite of the lower cost and better mass transfer of base and acid homogeneous catalysts, reaction system corrosion, non-reusability, and soap formation are serious challenges of these catalysts at an industrial scale. On the other hand, acid and base heterogenous catalysts overcame the issues of corrosion and recovery, but some matters such as mass transfer limitation, high cost, and weak performance in catalyzing both esterification of FFAs and transesterification of lipids must be taken into account. In addition, bio-catalysis as a high-cost process led to a purer product formation with less side reaction. Therefore, several significant factors should be considered for transesterification catalysts such as availability, cost, reusability, stability, mass transfer, and the possibility to manage both the transesterification of triglycerides and the esterification of FFAs, selecting a catalyst with predominant pros is viable. Here, a review of the biodiesel production from algal biomass focusing on the efficient catalyst of the process is presented