Comparison of potential adjustment variables representing primary intellectual level in epidemiological studies on neurotoxicity

BACKGROUND: Primary intellectual abilities (PIA) are a confounder in epidemiological studies on neurotoxicity. A good measure of this confounder should be independent of age as PIA is an intrinsic ability. Furthermore, as PIA is related to health endpoints, any measure of PIA should reveal this association. This study is aimed at comparing vocabulary test, diploma and age at end of schooling properties as measures of PIA in a non-exposed population of workers. METHODS: The design was a cross-sectional study of 413 non-exposed workers (203 women and 210 men) selected from a health check-up center. The effect of age on the vocabulary score was assessed using an analysis of covariance adjusted for diploma. Relationships between neuropsychological performances and vocabulary score, diploma and end of schooling age were, respectively, assessed using multiple linear regressions adjusted for age and gender. RESULTS: Vocabulary score increased significantly with age, both for men and women. The increase was 0.14 word per year for women, and 0.18 word per year for men. The explained variance of the models evaluating the relationships between age at end of schooling, diploma, vocabulary test, and neuropsychological performances was quite similar for the three measures of PIA. CONCLUSIONS: Vocabulary score was found to be age-related, even after adjustment for diploma. No difference was found between these three variables in terms of their relationship to neuropsychological endpoints. Moreover, the literature shows that vocabulary test performances are influenced by exposure to neurotoxic agents. These results suggest that vocabulary score could be of interest for participants of similar ages and similar diplomas. Otherwise, the other two variables would be better PIA measures in neurotoxicology studies.

System-level Support for Mobile Ad hoc Communications: an Algorithmic & Practical Approach

A mobile ad hoc network (MANET) is a decentralized and infrastructure-less network. This thesis aims to provide support at the system-level for developers of applications or protocols in such networks. To do this, we propose contributions in both the algorithmic realm and in the practical realm. In the algorithmic realm, we contribute to the field by proposing different context-aware broadcast and multicast algorithms in MANETs, namely six-shot broadcast, six-shot multicast, PLAN-B and ageneric algorithmic approach to optimize the power consumption of existing algorithms. For each algorithm we propose, we compare it to existing algorithms that are either probabilistic or context-aware, and then we evaluate their performance based on simulations. We demonstrate that in some cases, context-aware information, such as location or signal-strength, can improve the effciency. In the practical realm, we propose a testbed framework, namely ManetLab, to implement and to deploy MANET-specific protocols, and to evaluate their performance. This testbed framework aims to increase the accuracy of performance evaluation compared to simulations, while keeping the ease of use offered by the simulators to reproduce a performance evaluation. By evaluating the performance of different probabilistic algorithms with ManetLab, we observe that both simulations and testbeds should be used in a complementary way. In addition to the above original contributions, we also provide two surveys about system-level support for ad hoc communications in order to establish a state of the art. The first is about existing broadcast algorithms and the second is about existing middleware solutions and the way they deal with privacy and especially with location privacy. - Un réseau mobile ad hoc (MANET) est un réseau avec une architecture décentralisée et sans infrastructure. Cette thèse vise à fournir un support adéquat, au niveau système, aux développeurs d'applications ou de protocoles dans de tels réseaux. Dans ce but, nous proposons des contributions à la fois dans le domaine de l'algorithmique et dans celui de la pratique. Nous contribuons au domaine algorithmique en proposant différents algorithmes de diffusion dans les MANETs, algorithmes qui sont sensibles au contexte, à savoir six-shot broadcast,six-shot multicast, PLAN-B ainsi qu'une approche générique permettant d'optimiser la consommation d'énergie de ces algorithmes. Pour chaque algorithme que nous proposons, nous le comparons à des algorithmes existants qui sont soit probabilistes, soit sensibles au contexte, puis nous évaluons leurs performances sur la base de simulations. Nous montrons que, dans certains cas, des informations liées au contexte, telles que la localisation ou l'intensité du signal, peuvent améliorer l'efficience de ces algorithmes. Sur le plan pratique, nous proposons une plateforme logicielle pour la création de bancs d'essai, intitulé ManetLab, permettant d'implémenter, et de déployer des protocoles spécifiques aux MANETs, de sorte à évaluer leur performance. Cet outil logiciel vise à accroître la précision desévaluations de performance comparativement à celles fournies par des simulations, tout en conservant la facilité d'utilisation offerte par les simulateurs pour reproduire uneévaluation de performance. En évaluant les performances de différents algorithmes probabilistes avec ManetLab, nous observons que simulateurs et bancs d'essai doivent être utilisés de manière complémentaire. En plus de ces contributions principales, nous fournissons également deux états de l'art au sujet du support nécessaire pour les communications ad hoc. Le premier porte sur les algorithmes de diffusion existants et le second sur les solutions de type middleware existantes et la façon dont elles traitent de la confidentialité, en particulier celle de la localisation.

Changes of overweight and obesity in the adult Swiss population according to educational level, from 1992 to 2007.

In many high income developed countries, obesity is inversely associated with educational level. In some countries, a widening gap of obesity between educational groups has been reported. The aim of this study was to assess trends in body mass index (BMI) and in prevalence of overweight and obesity and their association with educational level in the adult Swiss population. Four cross-sectional National health interview surveys conducted in 1992/93 (n = 14,521), 1997 (n = 12,474), 2002 (n = 18,908) and 2007 (n = 17,879) using representative samples of the Swiss population (age range 18-102 years). BMI was derived from self-reported data. Overweight was defined as BMI > or = 25 and <30 kg/m(2), and obesity as BMI > or = 30 kg/m(2). Mean (+/- standard deviation) BMI increased from 24.7 +/- 3.6 in 1992/3 to 25.4 +/- 3.6 kg/m2 in 2007 in men and 22.8 +/- 3.8 to 23.7 +/- 4.3 kg/m(2) in women. Between 1992/3 and 2007, the prevalence of overweight + obesity increased from 40.4% to 49.5% in men and from 22.3% to 31.3% in women, while the prevalence of obesity increased from 6.3% to 9.4% in men and from 4.9% to 8.5% in women. The rate of increase in the prevalence of obesity was greater between 1992/3 and 2002 (men: +0.26%/year; women: +0.31%/year) than between 2002 and 2007 (men: +0.10%/year; women: +0.10%/year). A sizable fraction (approximately 25%) of the increasing mean BMI was due to increasing age of the participants over time. The increase was larger in low than high education strata of the population. BMI was strongly associated with low educational level among women and this gradient remained fairly constant over time. A weaker similar gradient by educational level was apparent in men, but it tended to increase over time. In Switzerland, overweight and obesity increased between 1992 and 2007 and was associated with low education status in both men and women. A trend towards a stabilization of mean BMI levels was noted in most age categories since 2002. The increase in the prevalence of obesity was larger in low education strata of the population. These findings suggest that obesity preventive measures should be targeted according to educational level in Switzerland.

Impact of genetic SLC28 transporter and ITPA variants on ribavirin 21 serum level, hemoglobin drop and therapeutic response in patients with HCV infection

Background: T reatment o f chronic hepatitis C i s evolving, a nd direct acting antivirals ( DAAs) are now a dded to p egylated interferon-α ( Peg- INF-α) and ribavirin (RBV) for the treatment o f hepatitis C v irus ( HCV) genotype 1 infection. DAAs c ause d ifferent side effects and can even worsen RBV induced hemolytic anemia. T herefore, identifying host genetic d eterminants of R BV bioavailability and therapeutic e fficacy will remain crucial for individualized treatment. Recent d ata showed associations between R BV induced h emolytic anemia and genetic polymorphisms o f concentrative nucleoside transporters s uch as C NT3 (SLC28A3) and i nosine t riphosphatase (ITPA). T o analyze t he association of genetic variants of SLC28 transporters and ITPA with RBV induced hemolytic anemia and treatment o utcome. Methods: I n our study, 173 patients f rom t he S wiss Hepatitis C C ohort Study and 2 2 patients from Swiss Association for the Study of the Liver study 24 (61% HCV g enotype 1, 3 9% genotypes 2 o r 3) were analyzed for SLC28A2 single nucleotide p olymorphism (SNP) rs11854484, SLC28A3 rs56350726 and SLC28A3 rs10868138 as well as ITPA SNPs rs1127354 and rs7270101. RBV serum levels during treatment were measured in 49 patients. Results: SLC28A2 r s11854484 genotype TT was associated with significantly higher dosage- and body weight-adjusted RBV levels as compared to genotypes TC and CC (p=0.04 and p=0.02 at weeks 4 and 8, respectively). ITPA SNPs rs1127354 and rs7270101 were associated with h emolytic a nemia both in genotype as w ell as i n allelic a nalyses. SLC28A3 rs56350726 genotype TT (vs. AT/AA, RR=2.1; 95% CI 1.1-4.1) as well as the T allele (vs. A; RR=1.8, 95% CI 1.1-3.2) were associated with increased SVR rates. The combined analysis of overall ITPA activity and SLC28 v ariants together revealed n o significant a dditive effects on either treatment-related anemia or SVR. Conclusions: T he newly identified association between RBV serum levels a nd SLC28A2 rs11854484 genotype as well as the replicated association of ITPA and SLC28A3 g enetic p olymorphisms w ith RBV induced hemolytic anemia and treatment r esponse underpin the need for further studies on host genetic d eterminants of R BV bioavailability and therapeutic e fficacy f or individualized treatment of chronic hepatitis C.

Raising the Level of Moral Thinking among Managers Will Not Help. Kohlberg's Conventionality and Systemic Ethical Flaws in Business

Business ethicists often assume that unethical behavior arises when individuals deviate from the norms and responsibilities that are institutionalized to frame economic activities. People's greed motivates them to violate the rules of the game. In Kohlberg's terms, it is assumed that such actors make decisions in a preconventional way and act opportunistically. In this article, we propose an alternative interpretation of deviant behavior, arguing that such behavior does not result from a lack of conventional moral guidance but rather from the fact that characteristics attributed to preconventional morality by Kohlberg - the purely incentive and punishment driven opportunistic morality - have become the conventionalized morality. The prevailing norms that economic actors have internalized as their yardstick are those of the preconventional Homo economicus. Not the deviation from, but the compliance with the rules of the game explains many forms of harmful and illegal decisions made in corporations.

Is the formula of Traub still up to date in antemortem blood glucose level estimation?

According to the hypothesis of Traub, also known as the 'formula of Traub', postmortem values of glucose and lactate found in the cerebrospinal fluid or vitreous humor are considered indicators of antemortem blood glucose levels. However, because the lactate concentration increases in the vitreous and cerebrospinal fluid after death, some authors postulated that using the sum value to estimate antemortem blood glucose levels could lead to an overestimation of the cases of glucose metabolic disorders with fatal outcomes, such as diabetic ketoacidosis. The aim of our study, performed on 470 consecutive forensic cases, was to ascertain the advantages of the sum value to estimate antemortem blood glucose concentrations and, consequently, to rule out fatal diabetic ketoacidosis as the cause of death. Other biochemical parameters, such as blood 3-beta-hydroxybutyrate, acetoacetate, acetone, glycated haemoglobin and urine glucose levels, were also determined. In addition, postmortem native CT scan, autopsy, histology, neuropathology and toxicology were performed to confirm diabetic ketoacidosis as the cause of death. According to our results, the sum value does not add any further information for the estimation of antemortem blood glucose concentration. The vitreous glucose concentration appears to be the most reliable marker to estimate antemortem hyperglycaemia and, along with the determination of other biochemical markers (such as blood acetone and 3-beta-hydroxybutyrate, urine glucose and glycated haemoglobin), to confirm diabetic ketoacidosis as the cause of death.

Performances et défaillances du sujet cérébral : regard anthropologique sur la plasticité cérébrale, les neurosciences et la clinique de la dégénérescence cognitive

Introduction 1.1 Le sujet cérébral, rencontre entre le biologique et le social L'objectif de ce travail est d'éclairer une des voies par lesquelles le phénomène anthropologique de l'individualité prend corps au sein de l'environnement contemporain. L'individualisme est compris comme les divers processus par lesquels la détermination du sujet tend à s'autonomiser des appartenances préconstituées. Il est la forme sociologique qui gouverne la façon contemporaine de faire société depuis l'avènement de la «modernité ». Le choix de l'angle de la cérébralité pour aborder la question de recherche repose sur le postulat qu'une des particularités culturelles de la figure du sujet individuel contemporain est la tendance à attribuer aux mécanismes cérébraux le rôle déterminant dans la constitution de la subjectivité du sujet. Dès lors, si aujourd'hui, penser le cerveau c'est penser l'humain, il s'agit d'un phénomène anthropologique qui demande à être explicité. Il m'appartient de démontrer que le champ des neurosciences se profile comme révélateur privilégié pour observer comment penser l'individualité concorde avec l'établissement de vérités relatives au cérébral' . Faire l'anthropologie du proche et de l'actuel a ses intérêts mais comporte aussi des risques. La perte de ce qui faisait le moteur de la recherche anthropologique -l'altérité donnée des sujets de son observation - a été compensée par l'émergence de nouveaux objets de travail et par des reconfigurations des rapports que l'anthropologue entretient avec son terrain. Le renouvellement du cadre de réflexion opéré par l'anthropologie au cours du siècle écoulé suit les transformations des pratiques sociales, culturelles et économiques qui s'opèrent au niveau mondial. L'échelle désormais planétaire de la circulation des acteurs sociaux et des objets de savoir a forcé la discipline à revoir la grille de lecture qui a longtemps opposé sociétés traditionnelles à sociétés modernes. La prise de conscience de la caducité du grand partage a engagé les anthropologues à s'intéresser à des phénomènes en rapport avec des problèmes rencontrés au sein de leur propre collectif et, dans le même mouvement, les a amenée à repenser les articulations entre le global et le local, le particulier et l'universel. Le bouleversement heuristique généré par ce repositionnement n'est toutefois pas exempt de nouvelles difficultés pour la recherche ethnographique. En se posant le défi d'étudier des traits culturels propres à sa société d'appartenance, l'anthropologie s'ouvre à des terrains enquête sur la façon dont, dans le monde occidental, le constat toujours plus pesant de la discordance entre les phénomènes de vieillissement cognitif et l'allongement de l'espérance de vie est traité. Dans une démarche ethnographique, il s'agit de voir quelles sont les logiques d'action et les pratiques sociales développées en réponse à ces inadéquations. La thématique impose une navigation entre des domaines théoriques spécialisés et des champs d'activités possédant chacun leurs cadres de référence. Une telle entreprise suppose une multiplication des systèmes de référence devant être pris en compte. Toutes les disciplines approchées au cours de ce travail abondent en métaphores utiles à la mise en ordre de leur pensée et à la description de leurs objets de travail. Toutefois, faire résonner entre elles les différentes «cultures épistémiques » (Knorr-Cetina, 1999) pour mieux faire apparaître la trame sociale qui constitue leur arrière-fond équivaut souvent à forcer le trait. Le sens des mots varie selon leurs champs d'application et l'exercice de la mise en résonance peut s'avérer périlleux. Je me suis efforcée tout au long de ces pages de préciser de quel point de vue les énoncés considérés sont formulés. L'analyse anthropologique étant guidée par la recherche des points de liaison entre les différents registres, la démarche est forcément limitée dans le niveau d'approfondissement auquel elle peut tendre. Elle risque de décevoir les lecteurs experts dans les domaines soumis à la grille de lecture de cette discipline, non familiers avec les concepts anthropologiques. Il est probable qu'un certain flou subsiste dans la façon dont ces énoncés sont décris par rapport au traitement dont ils sont l'objet dans leurs disciplines respectives. Si on perd de vue la préoccupation centrale de l'anthropologie, consistant à éclairer le système de valeurs commun sous-tendant les pratiques sociales observées, la lecture d'un tel travail risque effectivement de rater son but. En revanche, en acceptant d'emblée de se prêter à un décentrement par rapport à son modèle disciplinaire, le lecteur doit pouvoir appréhender des aspects intéressant ses propres pratiques. S'intéresser à ce qui relie les savoirs et les pratiques au sein d'un monde commun, voilà un programme heuristique qui va à l'encontre de la logique de spécialisation.

Quantification of clenbuterol at trace level in human urine by ultra-high pressure liquid chromatography-tandem mass spectrometry.

Clenbuterol is a β2 agonist agent with anabolic properties given by the increase in the muscular mass in parallel to the decrease of the body fat. For this reason, the use of clenbuterol is forbidden by the World Anti-Doping Agency (WADA) in the practice of sport. This compound is of particular interest for anti-doping authorities and WADA-accredited laboratories due to the recent reporting of risk of unintentional doping following the eating of meat contaminated with traces of clenbuterol in some countries. In this work, the development and the validation of an ultra-high pressure liquid chromatography coupled to electrospray ionization tandem mass spectrometry (UHPLC-ESI-MS/MS) method for the quantification of clenbuterol in human urine is described. The analyte was extracted from urine samples by liquid-liquid extraction (LLE) in basic conditions using tert butyl-methyl ether (TBME) and analyzed by UHPLC-MS/MS with a linear gradient of acetonitrile in 9min only. The simple and rapid method presented here was validated in compliance with authority guidelines and showed a limit of quantification at 5pg/mL and a linearity range from 5pg/mL to 300pg/mL. Good trueness (85.8-105%), repeatability (5.7-10.6% RSD) and intermediate precision (5.9-14.9% RSD) results were obtained. The method was then applied to real samples from eighteen volunteers collecting urines after single oral doses administration (1, 5 and 10μg) of clenbuterol-enriched yogurts.

Radiologists' vs. surgeons' reading performance in non traumatic acute abdomen CTs : P32

Purpose: Emergency room reading performances have been a point of interest in recent studies comparing radiologists to other physician groups. Our objective was to evaluate and compare the reading performances of radiologists and surgeons in an emergency room setting of non-traumatic abdominal CTs. Methods and materials: A total of ten readers representing four groups participated in this study: three senior radiologists and visceral surgeons, respectively, and two junior radiologists and surgeons, respectively. Each observer blindedly evaluated a total of 150 multi-slice acute abdominal CTs. CTs were chosen representing established proportions of acute abdomen pathologies in a Level I trauma centre from 2003 to 2005. Each answer was interpretated as right or wrong regarding pathology location, diagnosis and need for operation. Gold standard was the intraoperative result, and the clinical patient follow-up for non-operated patients. Significance was assumed at a p <.05 level. Results: Senior radiologists had a mean score of 2.38 ± 1.14, junior radiologists a score of 2.34 ± 1.14, whereas senior surgeons scored 2.07 ± 1.30 and junior surgeons 1.62 ± 1.42. No significant difference was found between the two radiologist groups, but results were significantly better for senior surgeons as compared to junior surgeons and better for the two radiologist groups as compared to each of the surgeon groups (all p <.05). Conclusion: Abdominal CT reading in an acute abdomen setting should continue to rely on an evaluation by a radiologist, whether senior or junior. Satisfying reading results can be achieved by senior visceral surgeons, but junior surgeons need more experience for a good reading performance.

Impact of low-level viremia on clinical and virological outcomes in treated HIV-1-infected patients.

BACKGROUND: The goal of antiretroviral therapy (ART) is to reduce HIV-related morbidity and mortality by suppressing HIV replication. The prognostic value of persistent low-level viremia (LLV), particularly for clinical outcomes, is unknown. OBJECTIVE: Assess the association of different levels of LLV with virological failure, AIDS event, and death among HIV-infected patients receiving combination ART. METHODS: We analyzed data from 18 cohorts in Europe and North America, contributing to the ART Cohort Collaboration. Eligible patients achieved viral load below 50 copies/ml within 3-9 months after ART initiation. LLV50-199 was defined as two consecutive viral loads between 50 and 199 copies/ml and LLV200-499 as two consecutive viral loads between 50 and 499 copies/ml, with at least one between 200 and 499 copies/ml. We used Cox models to estimate the association of LLV with virological failure (two consecutive viral loads at least 500 copies/ml or one viral load at least 500 copies/ml, followed by a modification of ART) and AIDS event/death. RESULTS: Among 17 902 patients, 624 (3.5%) experienced LLV50-199 and 482 (2.7%) LLV200-499. Median follow-up was 2.3 and 3.1 years for virological and clinical outcomes, respectively. There were 1903 virological failure, 532 AIDS events and 480 deaths. LLV200-499 was strongly associated with virological failure [adjusted hazard ratio (aHR) 3.97, 95% confidence interval (CI) 3.05-5.17]. LLV50-199 was weakly associated with virological failure (aHR 1.38, 95% CI 0.96-2.00). LLV50-199 and LLV200-499 were not associated with AIDS event/death (aHR 1.19, 95% CI 0.78-1.82; and aHR 1.11, 95% CI 0.72-1.71, respectively). CONCLUSION: LLV200-499 was strongly associated with virological failure, but not with AIDS event/death. Our results support the US guidelines, which define virological failure as a confirmed viral load above 200 copies/ml.

Direct binding of peptides to MHC class I molecules on living cells. Analysis at the single cell level.

To directly assess the binding of exogenous peptides to cell surface-associated MHC class I molecules at the single cell level, we examined the possibility of combining the use of biotinylated peptide derivatives with an immunofluorescence detection system based on flow cytometry. Various biotinylated derivatives of the adenovirus 5 early region 1A peptide 234-243, an antigenic peptide recognized by CTL in the context of H-2Db, were first screened in functional assays for their ability to bind efficiently to Db molecules on living cells. Suitable peptide derivatives were then tested for their ability to generate positive fluorescence signals upon addition of phycoerythrin-labeled streptavidin to peptide derivative-bearing cells. Strong fluorescent staining of Db-expressing cells was achieved after incubation with a peptide derivative containing a biotin group at the C-terminus. Competition experiments using the unmodified parental peptide as well as unrelated peptides known to bind to Kd, Kb, or Db, respectively, established that binding of the biotinylated peptide to living cells was Db-specific. By using Con A blasts derived from different H-2 congenic mouse strains, it could be shown that the biotinylated peptide bound only to Db among &gt; 20 class I alleles tested. Moreover, binding of the biotinylated peptide to cells expressing the Dbm13 and Dbm14 mutant molecules was drastically reduced compared to Db. Binding of the biotinylated peptide to freshly isolated Db+ cells was readily detectable, allowing direct assessment of the relative amount of peptide bound to distinct lymphocyte subpopulations by three-color flow cytometry. While minor differences between peripheral T and B cells could be documented, thymocytes were found to differ widely in their peptide binding activity. In all cases, these differences correlated positively with the differential expression of Db at the cell surface. Finally, kinetic studies at different temperatures strongly suggested that the biotinylated peptide first associated with Db molecules available constitutively at the cell surface and then with newly arrived Db molecules.

Fitness to drive and cannabis: Validation of two blood THCCOOH thresholds to distinguish occasional users from heavy smokers.

Many studies based on either an experimental or an epidemiological approach, have shown that the ability to drive is impaired when the driver is under the influence of cannabis. Baseline performances of heavy users remain impaired even after several weeks of abstinence. Symptoms of cannabis abuse and dependence are generally considered incompatible with safe driving. Recently, it has been shown that traffic safety can be increased by reporting the long-term unfit drivers to the driver licensing authorities and referring the cases for further medical assessment. Evaluation of the frequency of cannabis use is a prerequisite for a reliable medical assessment of the fitness to drive. In a previous paper we advocated the use of two thresholds based on 11-nor-9-carboxy-Δ9-tetrahydrocannabinol (THCCOOH) concentration in whole blood to help to distinguish occasional cannabis users (≤3μg/L) from heavy regular smokers (≥40μg/L). These criteria were established on the basis of results obtained in a controlled cannabis smoking study with placebo, carried out with two groups of young male volunteers; the first group was characterized by a heavy use (≥10 joints/month) while the second group was made up of occasional users smoking at most 1 joint/week. However, to date, these cutoffs have not been adequately assessed under real conditions. Their validity can now be evaluated and confirmed with 146 traffic offenders' real cases in which the whole blood cannabinoid concentrations and the frequency of cannabis use are known. The two thresholds were not challenged by the presence of ethanol (40% of cases) and of other therapeutic and illegal drugs (24%). Thus, we propose the following procedure that can be very useful in the Swiss context but also in other countries with similar traffic policies: if the whole blood THCCOOH concentration is higher than 40μg/L, traffic offenders must be directed first and foremost toward medical assessment of their fitness to drive. This evaluation is not recommended if the THCCOOH concentration is lower than 3μg/L and if the self-rated frequency of cannabis use is less than 1 time/week. A THCCOOH level between these two thresholds cannot be reliably interpreted. In such a case, further medical assessment and follow-up of the fitness to drive are also suggested, but with lower priority.

Relations intergroupes : attribution à la discrimination et perception d'hostilité chez autrui

Résumé: La thèse que nous présentons s'intéresse aux phénomènes d'attribution d'intentions hostiles. Dodge (1980) observe que les individus agressifs ont tendance, en situation ambiguë, à sur-attribuer des intentions hostiles à leurs pairs, ce qui induit des réponses agressives. Pour l'auteur, l'attribution d'intentions hostiles est un médiateur entre certaines caractéristiques personnelles (l'agressivité) des individus, et le type de réponses qu'ils apportent aux situations. Cependant, les informations concernant l'appartenance groupale des "pairs" ne sont jamais prises en compte dans leurs études. Si ce processus est perméable à l'influence des normes et croyances (Bègue et Muller, 2006), aucune étude ne met en évidence quel serait l'impact d'informations groupales sur l'élaboration des réponses aux situations, dans le cadre de ce modèle. L'objectif de cette thèse est de montrer que l'attribution d'intentions hostiles peut être envisagée comme un processus agissant également à un niveau intergroupes et donc prenant en compte des informations groupales sur les individus. En s'inspirant du modèle de Dodge, nous avons émis l'hypothèse que les logiques intergroupes intervenaient dans l'interprétation des intentions des acteurs impliqués dans les interactions, afin de produire une réponse adaptée aux logiques intergroupes. Afin de tester cette hypothèse, nous avons suivi trois axes de recherches: Dans le premier de ces axes, nous avons introduit, dans le paradigme de Dodge, des informations .sur l'appartenance groupale des protagonistes de l'interaction (endogroupe vs exogroupe). Nous avons montré que le type de situation (ambiguë vs hostile) est moins important que l'information groupale dans la production d'une réponse à la situation (Étude 1). En outre, nous avons mis en évidence des processus différents selon la position des individus dans leur groupe (Étude 2). Dans le second axe, nous avons montré que si les différences de statut entre groupes n'influençaient pas directement le modèle de Dodge, elles interagissaient avec l'appartenance groupale et la clarté de la situation au niveau de l'attribution d'intentions hostiles (étude 3) et des intentions comportementales (Ettide 4). Dans le troisième et deriúer axe, nous avons introduit l'attribution d'intentions hostiles dans un processus de dévalorisation d'une cible expliquant un échec par la discrimination (Kaiser et Miller, 2001; 2003). Nous avons alors montré que l'attribution d'intentions hostiles médiatisait le lien entre l'attribution mobilisée pour expliquer l'événement et l'évaluation de la cible (Étude 5), et que ce type d'attribution était spécifique, aux intentions comportementales agressives (Études 6). Nous avons alors conclu sur la dimension sociale de l'attribution d'intentions hostiles et sur le fait qu'il s'agissait d'un élément permettant la construction d'une représentation des interactions sociales. Abstract The present thesis focuses on the phenomena of hostile intents attribution. Dodge (1980) observes that in ambiguous situations, aggressive people tend to over attribute hostile intents to others. This attribution leads them to respond aggressively. According to the author, hostile intents attribution mediates the link between some personal characteristics (aggressiveness for example) of individuals and their responses to the situation. However information related to participants group membership is always neglected in these studies. Begue and Muller (2006) showed that some beliefs could moderate the interaction between aggressiveness and hostile intents attribution on behaviors, but no study exhibited evidence of a similar effect with social information. The aim of this thesis is to show that hostile intents attribution needs to be considered at an intergroup level by taking into account people's group ineinbership. Based on the Dodge model, we formulated the hypothesis that intergroup strategies had an impact on actors' intents interpretations which in return should lead to different but adapted reactions to the situation. To test this hypothesis, three lines of research were developed. In the first line, we introduced, in the Dodge's paradigm, some information about the participants group membership (ingroup vs outgroup). We showed that when elaborating a response to a specific situation its nature (ambiguous vs hostile) had less impact than group membership information (Study 1). In addition, we highlighted some different processes according to the position of individuals in their group (Study 2). In the second line, we showed that if the differences between groups status didn't influence the Dodge model, they interacted with group membership and situation nature to influence hostile intents attribution (Study 3) and behaviors intents (Study 4). In the last line of research, we introduced hostile intents attribution within the process of derogation of a target explaining its failure by discrimination (Kaiser and Miller, 2001; 2003). We showed that hostile intents attribution mediated the link between the attibution mobilized to explain the failure and the derogation of the target (Study 5), and that this attribution type was specifically linked to aggressive behavior intents (Study 6). We finally concluded that hostile intents attribution imply an important social dimension which needs to be taken into account because involved in the construction of a representation of social interactions.

Spatial modelling of biodiversity at the community level

1. Statistical modelling is often used to relate sparse biological survey data to remotely derived environmental predictors, thereby providing a basis for predictively mapping biodiversity across an entire region of interest. The most popular strategy for such modelling has been to model distributions of individual species one at a time. Spatial modelling of biodiversity at the community level may, however, confer significant benefits for applications involving very large numbers of species, particularly if many of these species are recorded infrequently. 2. Community-level modelling combines data from multiple species and produces information on spatial pattern in the distribution of biodiversity at a collective community level instead of, or in addition to, the level of individual species. Spatial outputs from community-level modelling include predictive mapping of community types (groups of locations with similar species composition), species groups (groups of species with similar distributions), axes or gradients of compositional variation, levels of compositional dissimilarity between pairs of locations, and various macro-ecological properties (e.g. species richness). 3. Three broad modelling strategies can be used to generate these outputs: (i) 'assemble first, predict later', in which biological survey data are first classified, ordinated or aggregated to produce community-level entities or attributes that are then modelled in relation to environmental predictors; (ii) 'predict first, assemble later', in which individual species are modelled one at a time as a function of environmental variables, to produce a stack of species distribution maps that is then subjected to classification, ordination or aggregation; and (iii) 'assemble and predict together', in which all species are modelled simultaneously, within a single integrated modelling process. These strategies each have particular strengths and weaknesses, depending on the intended purpose of modelling and the type, quality and quantity of data involved. 4. Synthesis and applications. The potential benefits of modelling large multispecies data sets using community-level, as opposed to species-level, approaches include faster processing, increased power to detect shared patterns of environmental response across rarely recorded species, and enhanced capacity to synthesize complex data into a form more readily interpretable by scientists and decision-makers. Community-level modelling therefore deserves to be considered more often, and more widely, as a potential alternative or supplement to modelling individual species.