82 resultados para Demography
Resumo:
Studies of behaviour are increasingly focusing on acquisition of traits through cultural inheritance. Comparison of patterns of spatial population structure (FST) between neutral genetic loci and behavioural or cultural traits can been used to test hypotheses about demography, life history, and the mechanisms of inheritance/transmission of these traits in humans, chimpanzees and other animals. Here, we develop analytical expectations to show how FST in cultural traits can differ strongly from that measured at neutral genetic markers if migration is largely restricted to one sex but social learning is predominantly modelled on the other (e.g. males migrate, females serve as models for cultural traits), if one individual is the learning model for many, or if rates of innovation (individual learning) are high or rates of social learning are low. We discuss how comparisons of FST between genetic loci and behavioural traits can be applied to evaluate the importance of innovation in shaping patterns of cultural differentiation, as even low rates of innovation can considerably reduce FST, relative to observed structure at neutral genetic loci. Our results also suggest that differentiation in neutral cultural traits should occur over much smaller scales in species with male migration and female enculturation (or the reverse).
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The aim of this study was to assess a population of patients with diabetes mellitus by means of the INTERMED, a classification system for case complexity integrating biological, psychosocial and health care related aspects of disease. The main hypothesis was that the INTERMED would identify distinct clusters of patients with different degrees of case complexity and different clinical outcomes. Patients (n=61) referred to a tertiary reference care centre were evaluated with the INTERMED and followed 9 months for HbA1c values and 6 months for health care utilisation. Cluster analysis revealed two clusters: cluster 1 (62%) consisting of complex patients with high INTERMED scores and cluster 2 (38%) consisting of less complex patients with lower INTERMED. Cluster 1 patients showed significantly higher HbA1c values and a tendency for increased health care utilisation. Total INTERMED scores were significantly related to HbA1c and explained 21% of its variance. In conclusion, different clusters of patients with different degrees of case complexity were identified by the INTERMED, allowing the detection of highly complex patients at risk for poor diabetes control. The INTERMED therefore provides an objective basis for clinical and scientific progress in diabetes mellitus. Ongoing intervention studies will have to confirm these preliminary data and to evaluate if management strategies based on the INTERMED profiles will improve outcomes.
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We investigate the evolutionary history of the greater white-toothed shrew across its distribution in northern Africa and mainland Europe using sex-specific (mtDNA and Y chromosome) and biparental (X chromosome) markers. All three loci confirm a large divergence between eastern (Tunisia and Sardinia) and western (Morocco and mainland Europe) lineages, and application of a molecular clock to mtDNA divergence estimates indicates a more ancient separation (2.25 M yr ago) than described by some previous studies, supporting claims for taxonomic revision. Moroccan ancestry for the mainland European population is inconclusive from phylogenetic trees, but is supported by greater nucleotide diversity and a more ancient population expansion in Morocco than in Europe. Signatures of rapid population expansion in mtDNA, combined with low X and Y chromosome diversity, suggest a single colonization of mainland Europe by a small number of Moroccan shrews >38 K yr ago. This study illustrates that multilocus genetic analyses can facilitate the interpretation of species' evolutionary history but that phylogeographic inference using X and Y chromosomes is restricted by low levels of observed polymorphism.
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[Table des matières] 1. Résumé. 2. Introduction. 3. Evolution démographique. 4. Evolution épidémiologique : infarctus du myocarde, insuffisance cardiaque, accident vasculaire cérébral, diabète, bronchopneumopathie chronique obstructive, cancer en général, cancer pulmonaire, cancer colorectal, cancer du sein, cancer de la prostate, dépression, démence sénile de type Alzheimer et autres démences, syndrome parkinsonien et maladie de Parkinson, maladie rhumatismale, arthrose, lombalgie, ostéoporose et fractures, déficit et dépendance fonctionnels. 5. Réponses sanitaires. 6. Recommandations. 7. Lexique. 8. Index des tableaux. 9. Index des figures. 10-11. Annexes.
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SUMMARY : Parasites and sociality in ants This thesis investigates the complex relationships between sociality, defences against parasites and the regulation of social structures. We studied how fungal parasites influenced colony organization, collective defences and social immunity in the ant Formica selysi. We first describe the diversity and prevalence of fungal pathogens associated with ant nests. The richness of fungal parasites community may increase the risk of multiple infections and select for a diversification of anti-parasitic defences in ants. Collective defences are powerful means to combat parasites, but can also increase the risk of disease transmission. Here, we showed that allo-grooming (mutual cleaning) was directed towards every returning individuals, be they contaminated or not. This collective behaviour removed conidia more efficiently than self-grooming but did not improve the survival of contaminated individuals. This suggests that allo-grooming may rather protect the group than cure contaminated individuals. It may also permit "social vaccination" if a contact with contaminated ants protects groomers frorn a second fungal exposure. Social transfer of immunity is an emerging theme in insect immunology. Here, we showed that ants in contact with an ant from a different genetic lineage had a higher disease resistance. We also found that naïve ants had a higher resistance after a contact with an immunized ant. This suggests that a transfer of resistance is possible and that "social vaccination" may improve the resistance of the group. However, it remains unclear whether repeated exposure to parasites may also increase the resistance of infected individuals themselves. lmmune memory in invertebrates is still debated. We tested whether immune priming against fungal parasite arose in ants and whether it was strain-specific. We found no evidence of immune priming. Naïve and immunized ants had a similar survival when infected. Together with our previous results, this suggests that ants have evolved efficient collective anti-fungal defences but that these defences aim at protecting the group rather than the contaminated individuals. ln colonies of our study population, there is a strong variation in the number of breeders. This is associated with important changes in life-history traits like demography or queen and worker body size. In the second part of the thesis, we investigated how social structures evolved and were maintained. We showed that queens from monogyne and polygyne colonies were able to found new colonies both alone or in association. We also found that there was no difference between monogyne and polygyne colonies in the acceptance of additional queens. These results suggest that a high plasticity has been maintained in this population, which may permit to adapt rapidly to changing environmental conditions. RESUME : Parasites et socialité chez les fourmis Durant cette thèse, nous avons étudié comment la socialité apporte de nouvelles réponses a des problèmes complexes telle que la défense contre les parasites ou l'organisation de la vie en groupe. Nous avons choisi comme modèle la fourmi Formica selysi et ses champignons pathogènes. Nous avons d'abord montré que la diversité et la prévalence de champignons pathogènes associés aux nids de fourmis étaient très élevées. Cela a pu pousser les fourmis à diversifier le champ de leur défenses anti-parasitaires afin d'éviter les infections multiples, La socialité a en particulier permis l'évolution de défenses collectives qui pourraient être plus efficaces que les défenses individuelles. Nous nous sommes donc intéressés de plus près aux défenses collectives et avons étudié quels en étaient les coûts et les bénéfices pour le groupe et pour ses membres. Nous avons trouvé que les fourmis nettoyaient tous les individus entrant dans la colonie, qu'ils soient contaminés ou non. Cela permettait d'ôter plus de spores que le nettoyage individuel et n'augmentait pas la transmission de maladie. Cependant, le nettoyage mutuel n'augmentait pas non plus la survie des individus contaminés. ll se pourrait donc que ce comportement serve plutôt a éviter une dissémination de la maladie qu'à soigner les individus contaminés. Le nettoyage mutuel pourrait aussi permettre aux individus sains d'avoir un premier contact non-létal avec un parasite et d'être vaccinés contre une future exposition. Cette hypothèse a été soutenue par une expérience dans laquelle nous avons montré que le contact avec une fourmi immunisée permettait d'augmenter la résistance d'individus naïfs. Les fourmis avaient aussi une meilleure résistance lorsqu'elles étaient en contact avec une fourmi provenant d'une autre lignée génétique. Cette "vaccination sociale" pourrait permettre d'une part d'augmenter le nombre d'espèce de parasites contre lesquelles le groupe serait protégé et d'autre part de faire l'économie d'autres défenses individuelles telles que la réponse immunitaire. Nous avons testé si les fourmis étaient elles-mêmes "vaccinées", c'est-à -dire, si elles exprimaient une mémoire immunitaire après un premier contact avec un champignon parasite. Nous n'avons trouvé aucune différence de survie entre les individus naïfs et immunisés ce qui suggère les fourmis favorisent d'autres défenses que la mémoire immunitaire contre les champignons entomopathogènes. Cela suggère également que les comportements coopératifs anti-parasitaires pourraient compléter, voire remplacer les défenses individuelles. La socialité telle qu'elle est pratiquée par les fourmis pose un autre problème de poids qui est celui de savoir combien d'individus se reproduisent. En effet, si les ouvrières sont stériles, le nombre de reines assurant la reproduction peut varier considérablement. Dans la population de E sebrsi étudiée, les colonies monogynes (une reine) co-existent avec des colonies polygynes (plusieurs reines) dans le même habitat. Nous nous sommes demandés si ces structures sociales étaient fixes ou si un changement de l'une à l'autre était possible. Pour cela nous avons comparé la fondation de nouvelles colonies par les jeunes reines issues de colonies monogynes et polygynes. Nous avons également observé si l'acceptation de nouvelles reines était possible dans les deux types de colonies. Nous n'avons trouvé aucune différence entre les deux types de colonies. Cela suggère qu'un changement est possible et que l'évolution des structures sociales est un processus dynamique. Cela pourrait être dû à l'habitat particulièrement changeant dans lequel se trouve notre population qui exigerait d'être capable de s'adapter très rapidement a de nouvelles conditions.
Resumo:
When individuals learn by trial-and-error, they perform randomly chosen actions and then reinforce those actions that led to a high payoff. However, individuals do not always have to physically perform an action in order to evaluate its consequences. Rather, they may be able to mentally simulate actions and their consequences without actually performing them. Such fictitious learners can select actions with high payoffs without making long chains of trial-and-error learning. Here, we analyze the evolution of an n-dimensional cultural trait (or artifact) by learning, in a payoff landscape with a single optimum. We derive the stochastic learning dynamics of the distance to the optimum in trait space when choice between alternative artifacts follows the standard logit choice rule. We show that for both trial-and-error and fictitious learners, the learning dynamics stabilize at an approximate distance of root n/(2 lambda(e)) away from the optimum, where lambda(e) is an effective learning performance parameter depending on the learning rule under scrutiny. Individual learners are thus unlikely to reach the optimum when traits are complex (n large), and so face a barrier to further improvement of the artifact. We show, however, that this barrier can be significantly reduced in a large population of learners performing payoff-biased social learning, in which case lambda(e) becomes proportional to population size. Overall, our results illustrate the effects of errors in learning, levels of cognition, and population size for the evolution of complex cultural traits. (C) 2013 Elsevier Inc. All rights reserved.
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quantiNemo is an individual-based, genetically explicit stochastic simulation program. It was developed to investigate the effects of selection, mutation, recombination and drift on quantitative traits with varying architectures in structured populations connected by migration and located in a heterogeneous habitat. quantiNemo is highly flexible at various levels: population, selection, trait(s) architecture, genetic map for QTL and/or markers, environment, demography, mating system, etc. quantiNemo is coded in C++ using an object-oriented approach and runs on any computer platform. Availability: Executables for several platforms, user's manual, and source code are freely available under the GNU General Public License at http://www2.unil.ch/popgen/softwares/quantinemo.
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[Table des matières] Technology assessment in health care in the United States: an historical review / S. Perry. - The aims and methods of technology assessment / JH Glasser. - Evaluation des technologies de la santé / A. Griffiths. - Les données nécessaires pour l'évaluation des technologies médicales / R. Chrzanowski, F. Gutzwiller, F. Paccaud. - Economic issues in technology assessment/DR Lairson, JM Swint. - Two decades of experience in technology assessment: evaluating the safety, performance, and cost effectiveness of medical equipment / JJ Nobel. - Demography and technology assessment / H. Hansluwka. - Méthodes expérimentale et non expérimentale pour l'évaluation des innovations technologiques / R. Chrzanowski, F. Paccaud. - Skull radiography in head trauma: a successful case of technology assessment / NT Racoveanu. - Complications associées à l'anesthésie: une étude prospective en France / L. Tiret et al. - Impact de l'information publique sur les taux opératoires: le cas de l'hystérectomie / G. Domenighetti, P. Luraschi, A. Casabianca. - The clinical effectiveness of acupuncture for the relief of chronic pain / MS Patel, F. Gutzwiller, F. Paccaud, A. Marazzi. - Soins à domicile et hébergement à long terme: à la recherche d'un développement optimum / G. Tinturier. - Economic evaluation of six scenarios for the treatment of stones in the kidney and ureter by surgery or ESWL / MS Patel et al. - Technology assessment and medical practice / F. Gutzwiller. - Technology assessment and health policy / SJ Reiser. - Global programme on appropriate technology for health, its role and place within WHO / K. Staehr Johansen.
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Experimental research has identified many putative agents of amphibian decline, yet the population-level consequences of these agents remain unknown, owing to lack of information on compensatory density dependence in natural populations. Here, we investigate the relative importance of intrinsic (density-dependent) and extrinsic (climatic) factors impacting the dynamics of a tree frog (Hyla arborea) population over 22 years. A combination of log-linear density dependence and rainfall (with a 2-year time lag corresponding to development time) explain 75% of the variance in the rate of increase. Such fluctuations around a variable return point might be responsible for the seemingly erratic demography and disequilibrium dynamics of many amphibian populations.
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Upward trends in mortality from hepatocellular carcinoma (HCC) were recently reported in the United States and Japan. Comprehensive analyses of most recent data for European countries are not available. Age-standardized (world standard) HCC rates per 100,000 (at all ages, at age 20-44, and age 45-59 years) were computed for 23 European countries over the period 1980-2004 using data from the World Health Organization. Joinpoint regression analysis was used to identify significant changes in trends, and annual percent change were computed. Male overall mortality from HCC increased in Austria, Germany, Switzerland, and other western countries, while it significantly decreased over recent years in countries such as France and Italy, which had large upward trends until the mid-1990s. In the early 2000s, among countries allowing distinction between HCC and other liver cancers, the highest HCC rates in men were in France (6.8/100,000), Italy (6.7), and Switzerland (5.9), whereas the lowest ones were in Norway (1.0), Ireland (0.8), and Sweden (0.7). In women, a slight increase in overall HCC mortality was observed in Spain and Switzerland, while mortality decreased in several other European countries, particularly since the mid-1990s. In the early 2000s, female HCC mortality rates were highest in Italy (1.9/100,000), Switzerland (1.8), and Spain (1.5) and lowest in Greece, Ireland, and Sweden (0.3). In most countries, trends at age 45-59 years were consistent with overall ones, whereas they were more favorable at age 20-44 years in both sexes. CONCLUSION: HCC mortality remains largely variable across Europe. Favorable trends were observed in several European countries mainly over the last decade, particularly in women and in young adults.
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OBJECTIVE: To report on the demographic data from the first 18 months of enrollment to an international registry on autoinflammatory diseases in the context of the Eurofever project. METHODS: A web-based registry collecting baseline and clinical information on autoinflammatory diseases and related conditions is available in the member area of the PRINTO web-site. Anonymised data were collected with standardised forms. RESULTS: 1880 (M:F=916:964) individuals from 67 centers in 31 countries have been entered in the Eurofever registry. Most of the patients (1388; 74%), reside in western Europe, 294 (16%) in the eastern and southern Mediterranean region (Turkey, Israel, North Africa), 106 (6%) in eastern Europe, 54 in Asia, 27 in South America and 11 in Australia. In total 1049 patients with a clinical diagnosis of a monogenic autoinflammatory diseases have been enrolled; genetic analysis was performed in 993 patients (95%): 703 patients have genetically confirmed disease and 197 patients are heterozygous carriers of mutations in genes that are mutated in patients with recessively inherited autoinflammatory diseases. The median diagnosis delay was 7.3 years (range 0.3-76), with a clear reduction in patients born after the identification of the first gene associated with autoinflammatory diseases in 1997. CONCLUSIONS: A shared online registry for patients with autoinflammatory diseases is available and enrollment is ongoing. Currently, there are data available for analysis on clinical presentation, disease course, and response to treatment, and to perform large scale comparative studies between different conditions.
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Using data from the Public Health Service, we studied the demographic and clinical characteristics of 1,782 patients enrolled in methadone maintenance treatment (MMT) during 2001 in the Swiss Canton of Vaud, comparing our findings with the results of a previous study from 1976 to 1986. In 2001, most patients (76.9%) were treated in general practice. Mortality is low in this MMT population (1%/year). While patient age and sex profiles were similar to those found in the earlier study, we did observe a substantial increase in the number of patients and the number of practitioners treating MMT patients, probably reflecting the low-threshold governmental policies and the creation of specialized centers. In conclusion, easier access to MMT enhances the number of patients, but new concerns about the quality of management emerge: benzodiazepine as a concomitant prescription; low rates of screening for hepatitis B, C and HIV, and social and psychiatric preoccupations.
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Owing to increasing rates of hypertension and cardiovascular-related diseases in developing countries, compliance with antihypertensive medication is major public health importance. Few studies have reported on compliance in developing countries. We determined the compliance of 187 patients with uncontrolled hypertension in the Seychelles (Indian Ocean), by assessing the presence of a biologic marker (riboflavin) in the urine. The urine tested positive in 56% of the cases. Compliance varied from one physician to another (highest 72% versus lowest 33%, P = 0.003), improved with the level of literacy (62% versus 45%, P = 0.024), and depended on the presence absence of diuretics in the medication (respectively, 45% versus 66%, P = 0.005). The ability of patients to report correctly the number of antihypertensive pills to be taken daily was a predictor of compliance (62% of the patients who gave appropriate answers had positive urine for the marker versus 31% for those giving inappropriate answers).