Search results for "Statistiques"
showing 10 items of 48 documents
Accounting for preferential sampling in species distribution models
2019
D. C., A. L. Q. and F. M. would like to thank the Ministerio de Educación y Ciencia (Spain) for financial support (jointly financed by the European Regional Development Fund) via Research Grants MTM2013‐42323‐P and MTM2016‐77501‐P, and ACOMP/2015/202 from Generalitat Valenciana (Spain). Species distribution models (SDMs) are now being widely used in ecology for management and conservation purposes across terrestrial, freshwater, and marine realms. The increasing interest in SDMs has drawn the attention of ecologists to spatial models and, in particular, to geostatistical models, which are used to associate observations of species occurrence or abundance with environmental covariates in a fi…
Bayesian spatio-temporal approach to identifying fish nurseries by validating persistence areas
2015
Spatial and temporal closures of fish nursery areas to fishing have recently been recognized as useful tools for efficient fisheries management, as they preserve the reproductive potential of populations and increase the recruitment of target species. In order to identify and locate potential nursery areas for spatio-temporal closures, a solid understanding of species− environment relationships is needed, as well as spatial identification of fish nurseries through the application of robust analyses. One way to achieve knowledge of fish nurseries is to analyse the persistence of recruitment hotspots. In this study, we propose the comparison of different spatiotemporal model structures to ass…
Bayesian spatio-temporal discard model in a demersal trawl fishery
2014
Spatial management of discards has recently been proposed as a useful tool for the protection of juveniles, by reducing discard rates and can be used as a buffer against management errors and recruitment failure. In this study Bayesian hierarchical spatial models have been used to analyze about 440 trawl fishing operations of two different metiers, sampled between 2009 and 2012, in order to improve our understanding of factors that influence the quantity of discards and to identify their spatio-temporal distribution in the study area. Our analysis showed that the relative importance of each variable was different for each metier, with a few similarities. In particular, the random vessel eff…
Modelling sensitive elasmobranchs habitat
2013
Basic information on the distribution and habitat preferences of ecologically important species is essential for their management and protection. In the Mediterranean Sea there is increasing concern over elasmobranch species because their biological (ecological) characteristics make them highly vulnerable to fishing pressure. Their removal could affect the structure and function of marine ecosystems, inducing changes in trophic interactions at the community level due to the selective elimination of predators or prey species, competitors and species replacement. In this study Bayesian hierarchical spatial models are used to map the sensitive habitats of the three most caught elasmobranch spe…
GeneSys-Beet: A model of the effects of cropping systems on gene flow between sugar beet and weed beet
2008
A weedy form of the genus Beta, i.e. Beta vulgaris ssp. vulgaris (hence ''weed beet'') frequently found in sugar beet is impossible to eliminate with herbicides because of its genetic proximity to the crop. It is presumed to be the progeny of accidental hybrids between sugar beet (ssp. vulgaris) and wild beet (ssp. maritima), or of sugar beet varieties sensitive to vernalization and sown early in years with late cold spells. In this context, genetically modified (GM) sugar beet varieties tolerant to non-selective herbicides would be interesting to manage weed beet. However, because of the proximity of the weed to the crop, it is highly probable that the herbicide-tolerance transgene would b…
La délimitation de la citoyenneté en Côte-d'Or, d'après le droit électoral de la IIe République
1997
One of the essential elements of citizenship lies in participating in politics. Il is particulary through the right to vote that man will be fully integrated into society and take part in the decisions concerning the running of the government. Adopting universal suffrage is giving an important power to men. Thus, certain rulers have tried to channel the vote by excluding citizens liable to be detrimental to them. The law of May 31, 1850 meant to eliminate the « vile multitude », according to the expression used by Thiers. And it is in particular through the study of the concrete consequences of this law that the influence of the electoral system in the definition of citizenship can be measu…
Ondes scélérates et statistiques extrêmes dans les systèmes optiques fibrés
2011
This thesis deals with extremes statistics which has become an attractive subject in optics since a comparison with oceanic rogue waves has been proposed at the end of 2007. We report some potential mechanisms stimulating the rogue wave formation in the context of guided propagation of light in optical fibers. In a first part, we explore optical rogue waves in supercontinuums generated by fourth-order modulation instability and we propose a stabilization method based on the use of two continuous seeds. Then, we present a detailed study on Raman fiber amplifiers where we determine the conditions of emergence of giant structures : in presence of a partially incoherent pumping wave, a quasi-in…
The Stressors-Performance Relationship in Public Accounting Firms: A Longitudinal Study
2021
Purpose: This study aims to examine the causal nature of the suggested correlations between stressors and performance in accounting and auditing firms.Design: A longitudinal study of the relationships between role stressors and performance of 71 chartered public accountants and trainee-chartered accountants surveyed before and after the fiscal period has been conducted using the partial least squares approach.Findings: The variation of stress arousal is positively associated with the variations of role conflict and overload, but not with the variations of role ambiguity and stress arousal. The variation of burnout arousal is positively related to the variation of stress arousal and, unexpec…
It’s a matter of confidence. Institutions, government stability and economic outcomes
2021
In this paper we analyse the effect of constitutional structures over policy outcomes. In particular, we exploit the heterogeneity in parliamentary systems deriving from the presence and the use of the confidence vote to investigate whether stable and unstable parliamentary systems behave differently in terms of the policies they implement. This finer partition of parliamentary systems allows us to identify effects that are more robust than the ones previously discussed in the literature. We show that the difference between presidential and parliamentary systems documented in previous works is driven by a difference between presidential and stable parliamentary systems. We suggest that poss…
Analyse des comportements différentiels selon le sexe chez les 50-74 ans : le cas de la participation électorale (France et Etats-Unis)
2022
La tranche d’âges des 50-74 ans a changé de caractéristiques après la transition démographique dans les pays occidentaux : la mortalité y est maintenant faible et peu différenciée entre les sexes. Pourtant, cette tranche d’âges conserve une caractéristique qui la distingue de celle des 25-49 ans : son infécondité, en raison principalement de l’infertilité des femmes après 45 ans. L’objectif de l’étude est d’abord d’analyser la pertinence d’un découpage par tranches d’âges qui utiliserait ces critères démographiques à la place du découpage socio-économique traditionnel construit notamment autour de l’âge de 60 ou 65 ans qui correspond à l’âge de départ à la retraite. Les différences de compo…