501 research outputs found
Environmental Policy, Public Interest and Political Market
In this article, we highlight the factors which influence governments in their decision to implement environmental policies of varying degrees of severity. We substantiate our arguments with analytical evidence from public interest theory and the economic theory of regulation (interest group theory). We demonstrate, through empirical analysis based on the policies of the 22 most developed OECD countries, that pressure groups have sufficient impact on environmental regulation for us to be sure that economic theory outweighs public interest theory. Ces derniĂšres dĂ©cennies, nous avons Ă©tĂ© tĂ©moins d'une prise de conscience collective sur les problĂšmes affectant la sauvegarde de notre patrimoine terrestre. Cependant, cette implication des pouvoirs publics dans ce domaine n'est pas uniforme. En effet, les lĂ©gislations adoptĂ©es Ă l'Ă©chelle de la planĂšte varient encore grandement dans leur application, d'un pays Ă l'autre. Dans ce travail, nous nous intĂ©ressons Ă cet Ă©tat de fait en mettant notamment en exergue les facteurs qui influencent les Ătats Ă instaurer une rĂ©glementation plus ou moins stricte. Pour ce faire, nous Ă©tayerons notre argumentation grĂące aux Ă©lĂ©ments d'analyse apportĂ©s par la thĂ©orie de l'intĂ©rĂȘt public et par ceux de la thĂ©orie Ă©conomique de la rĂ©glementation (thĂ©orie souvent mentionnĂ©e comme thĂ©orie des groupes d'intĂ©rĂȘt). Nous nous apercevrons, au grĂ© d'un travail empirique visant Ă analyser les politiques des 22 pays les plus dĂ©veloppĂ©s de l'OCDE, que les groupes de pression ont un impact suffisant sur la rĂ©glementation environnementale pour nous assurer de la prĂ©pondĂ©rance de la thĂšse stiglerienne (thĂ©orie Ă©conomique) sur la thĂ©orie de l'intĂ©rĂȘt public ou gĂ©nĂ©ral.Regulation, environment, public interest, political market, RĂ©glementation, environnement, intĂ©rĂȘt public, marchĂ© politique
Analysis of micro-seismicity in sea ice with deep learning and Bayesian inference: application to high-resolution thickness monitoring
In the perspective of upcoming seasonally ice-free Arctic, understanding the dynamics of sea ice in the changing climate is a major challenge in oceanography and climatology. In particular, the new generation of sea ice models will require fine parameterization of sea ice thickness and rheology. With the rapidly evolving state of sea ice, achieving better accuracy, as well as finer temporal and spatial resolutions of its thickness will set new monitoring standards, with major scientific and geopolitical implications. Recent studies have shown the potential of passive seismology to monitor the thickness, density and elastic properties of sea ice with significantly reduced logistical constraints. For example, human intervention is no longer required, except to install and uninstall the geophones. Building up on this approach, we introduce a methodology for estimating sea ice thickness with high spatial and temporal resolutions from the analysis of icequakes waveforms. This methodology is based on a deep convolutional neural network for automatic clustering of the ambient seismicity recorded on sea ice, combined with a Bayesian inversion of the clustered waveforms. By applying this approach to seismic data recorded in March 2019 on fast ice in the Van Mijen fjord (Svalbard), we observe the spatial clustering of icequakes sources along the shore line of the fjord. The ice thickness is shown to follow an increasing trend that is consistent with the evolution of temperatures during the four weeks of data recording. Comparing the energy of the icequakes with that of calibrated seismic sources, we were able to derive a power law of icequake energy, and to relate this energy to the size of the cracks that generate the icequakes.</p
Absence of Nodal signaling promotes precocious neural differentiation in the mouse embryo
AbstractAfter implantation, mouse embryos deficient for the activity of the transforming growth factor-ÎČ member Nodal fail to form both the mesoderm and the definitive endoderm. They also fail to specify the anterior visceral endoderm, a specialized signaling center which has been shown to be required for the establishment of anterior identity in the epiblast. Our study reveals that Nodalâ/â epiblast cells nevertheless express prematurely and ectopically molecular markers specific of anterior fate. Our analysis shows that neural specification occurs and regional identities characteristic of the forebrain are established precociously in the Nodalâ/â mutant with a sequential progression equivalent to that of wild-type embryo. When explanted and cultured in vitro, Nodalâ/â epiblast cells readily differentiate into neurons. Genes normally transcribed in organizer-derived tissues, such as Gsc and Foxa2, are also expressed in Nodalâ/â epiblast. The analysis of Nodalâ/â;Gscâ/â compound mutant embryos shows that Gsc activity plays no critical role in the acquisition of forebrain characters by Nodal-deficient cells. This study suggests that the initial steps of neural specification and forebrain development may take place well before gastrulation in the mouse and highlights a possible role for Nodal, at pregastrula stages, in the inhibition of anterior and neural fate determination
Ecologie évolutive du transfert trans-générationnel d'immunité chez un insecte
Le transfert trans-gĂ©nĂ©rationnel d immunitĂ© (TTGI) est dĂ©fini comme Ă©tant une Ă©lĂ©vation de l immunocompĂ©tence de la descendance suite Ă la rencontre des femelles avec un organisme pathogĂšne. Le TTGI est un phĂ©nomĂšne bien connu chez les vertĂ©brĂ©s, chez lesquels il se rĂ©alise par le transfert d anticorps de la mĂšre au jeune. Il n a Ă©tĂ© dĂ©crit que rĂ©cemment chez les invertĂ©brĂ©s, chez lesquels le support de sa transmission est encore inconnu. Le TTGI apporte un bĂ©nĂ©fice aux descendants lorsqu ils rencontrent l infection vĂ©cue par la mĂšre, dans quel cas l Ă©lĂ©vation de leur immunocompĂ©tence a un effet protecteur. Cependant, au-delĂ de ce bĂ©nĂ©fice, plusieurs indices suggĂšrent que le TTGI est un phĂ©nomĂšne coĂ»teux pour les organismes. L Ă©volution du TTGI ne sera permise chez une espĂšce que lorsque les bĂ©nĂ©fices qu il reprĂ©sente en termes de protection des descendants surpasseront les coĂ»ts qu il reprĂ©sente pour eux en termes de fitness. Ainsi, l Ă©tude de ses coĂ»ts et de ses bĂ©nĂ©fices nous renseigne sur les pressions de sĂ©lection qui ont conduit Ă son Ă©volution chez les invertĂ©brĂ©s. Au cours de cette thĂšse, j ai associĂ© l expression du TTGI chez un insecte avec un certain nombre de coĂ»ts, tant pour les femelles qui le rĂ©alisent que pour les descendants qui l expriment. Pour ce faire, j ai utilisĂ© comme organisme modĂšle le ver de farine, Tenebrio molitor. Dans le premier chapitre, nous avons stimulĂ© le systĂšme immunitaire des femelles adultes de T. molitor avec un immunogĂšne non pathogĂšne, et Ă©tudiĂ© divers aspects de la transmission d activitĂ© antibactĂ©rienne aux Ćufs qui en rĂ©sultait. Cela nous a permis de voir que la transmission d activitĂ© antibactĂ©rienne interne aux Ćufs commençait deux jours aprĂšs la stimulation du systĂšme immunitaire des femelles et cessait aprĂšs dix jours. Enfin, nous avons pu mettre en Ă©vidence un coĂ»t pour les femelles Ă la protection de leurs Ćufs, en termes de fĂ©conditĂ©. Dans le second chapitre, nous stimulĂ© le systĂšme immunitaire avec trois microorganismes diffĂ©rents tuĂ©s par la chaleur, et exposĂ© leurs jeunes larves Ă des microorganismes vivants. Nous n avons pas rĂ©ussi Ă mettre en Ă©vidence d effet protecteur du TTGI sur les jeunes larves de T. molitor. Il s avĂšre cependant que l exposition des jeunes larves Ă un champignon entomopathogĂšne rĂ©duit le dĂ©lai avant leur seconde mue larvaire. Dans le troisiĂšme chapitre, nous avons stimulĂ© soit le systĂšme immunitaire des femelles, soit celui des mĂąles de T. molitor avec un immunogĂšne non pathogĂšne, et observĂ© diffĂ©rents paramĂštres de l immunitĂ© de leurs descendants adultes. Cela nous a permis de mettre en Ă©vidence que le TTGI d origine maternelle et paternelle n affecte pas les mĂȘmes effecteurs immunitaires chez les descendants, et que le TTGI d origine maternelle comportait un coĂ»t pour eux en termes de temps de dĂ©veloppement. Ces coĂ»ts au TTGI suggĂšrent qu il n est pas seulement une consĂ©quence de la stimulation du systĂšme immunitaire des femelles de la gĂ©nĂ©ration parentale, mais qu il est bien un mĂ©canisme qui a Ă©tĂ© sĂ©lectionnĂ© du fait des bĂ©nĂ©fices qu il reprĂ©sente pour les organismes dans certaines conditions Ă©cologiquesTrans-generational immune priming (TGIP) is defined as the plastic enhancement of offspring's immunocompetence following an immune challenge of the females of the parental generation. In vertebrates, this phenomenon is well described, and is achieved by the maternal transfer of antibodies. In invertebrates however, it has only recently been described. Since invertebrates do not possess antibodies, the mechanism of this transmission remains unknown. If the offspring is exposed to the maternal infection, an elevated immunocompetence can help it cope better with it. Nonetheless, apart from this benefit, several cues indicate that the TGIP bears some fitness costs for individuals. The evolution of TGIP will be favoured when its benefits outweigh its fitness costs. Thus, studying its costs and benefits can lead us to a better understanding of the selection pressures that lead to its evolution in invertebrates. During my thesis, I associated the occurrence of TGIP in an insect, the mealworm beetle Tenebrio molitor, to several fitness costs for the females transmitting it as well as for the offspring receiving it.In the first chapter, we stimulated the adult female's immune system with a non pathogenic immunogene, and studied several aspects of the subsequent transfer of antibacterial activity to the eggs. We saw that the transmission of antibacterial activity inside the eggs started two days after the immune challenge, and stopped at ten. Then, we highlighted a cost for the females on their fecundity to this transmission.In the second chapter, we stimulated the immune system of the females with three different heat-killed microorganisms, and exposed their larval progeny to living microorganisms. We did not see any benefit of the TGIP on the young larvae of T. molitor. However, we saw that the exposure of young larvae to an entomopathogenic fungus decreased the time-lap between the two first larval moults.In the third chapter, we stimulated the immune system of either the adult females or the males of T. molitor, and we observed several immune parameters in their adult offspring. This allowed us to see that maternally and paternally-derived TGIP affected different immune effectors in the adult offspring, and that maternally-derived TGIP bear a cost on the developmental time of the offspring.These fitness costs to the TGIP suggest that it is not just a side-effect of the immune reaction of the females, but rather an investment that has been selected because of the benefits it represents for the offspring in certain ecological conditionsDIJON-BU Doc.Ă©lectronique (212319901) / SudocSudocFranceF
Savigny-sous-Faye â Place de l'Ă©glise
Identifiant de l'opĂ©ration archĂ©ologique : 204643 Date de l'opĂ©ration : 2008 (SU) LâopĂ©ration de sauvetage urgent rĂ©alisĂ©e sur la place de lâĂ©glise de Savigny-sous-Faye a Ă©tĂ© dĂ©clenchĂ©e par un projet dâamĂ©nagement de la place et dâassainissement des environs de lâĂ©glise Saint-Pierre, protĂ©gĂ©e au titre des Monuments Historiques depuis 1994. Savigny-sous-Faye est une commune du nord de la Vienne qui se situe Ă Â 20 km au nord-est de ChĂątellerault au cĆur dâune vaste plaine Ă vocation agricole cĂ©..
Virulent Synergistic Effect between Enterococcus faecalis and Escherichia coli Assayed by Using the Caenorhabditis elegans Model
5 pagesInternational audienceBACKGROUND: The role of enterococci in the pathogenesis of polymicrobial infections is still debated. The purpose of this study was to evaluate the effect of virulent enterococci in the presence or absence of Escherichia coli strains in the in vivo Caenorhabditis elegans model. PRINCIPAL FINDINGS: This study demonstrated that there was a synergistic effect on virulence when an association of enterococci and E. coli (LT50 = 1.6 days+/-0.1 according to the tested strains and death of nematodes in 4 days+/-0.5) was tested in comparison with enterococci alone (LT50 = 4.6 days+/-0.1 and death in 10.4 days+/-0.6) or E. coli alone (LT50 = 2.1+/-0.9 and deaths 6.6+/-0.6) (p<0.001). In addition, there was a relation between the virulence of E. faecalis strains alone and the virulence potential of the association with E. coli strains. Finally, in the presence of avirulent E. coli strains, enterococci have no effect (LT50 = 4.3+/-0.5 and deaths in 10.8+/-0.8), independently of the level of their own virulence, demonstrating that the 'enterococci effect' only occurred in the presence of virulent E. coli strains. CONCLUSION: This study allows a better understanding of a bacterial cooperation. Moreover, it could help to optimize the antibiotic regimen during polymicrobial infections
Towards a monolithic optical cavity for atom detection and manipulation
We study a Fabry-Perot cavity formed from a ridge waveguide on a AlGaAs
substrate. We experimentally determined the propagation losses in the waveguide
at 780 nm, the wavelength of Rb atoms. We have also made a numerical and
analytical estimate of the losses induced by the presence of the gap which
would allow the interaction of cold atoms with the cavity field. We found that
the intrinsic finesse of the gapped cavity can be on the order of F ~ 30,
which, when one takes into account the losses due to mirror transmission,
corresponds to a cooperativity parameter for our system C ~ 1
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