606 resultados para Demography.
Resumo:
Background: Conifer populations appear disproportionately threatened by global change. Most examples are, however, drawn from the northern hemisphere and long-term rates of population decline are not well documented as historical data are often lacking. We use a large and long-term (1931-2013) repeat photography dataset together with environmental data and fire records to account for the decline of the critically endangered Widdringtonia cedarbergensis. Eighty-seven historical and repeat photo-pairs were analysed to establish 20th century changes in W. cedarbergensis demography. A generalized linear mixed-effects model was fitted to determine the relative importance of environmental factors and fire-return interval on mortality for the species. Results: From an initial total of 1313 live trees in historical photographs, 74% had died and only 44 (3.4%) had recruited in the repeat photographs, leaving 387 live individuals. Juveniles (mature adults) had decreased (increased) from 27% (73%) to 8% (92%) over the intervening period. Our model demonstrates that mortality is related to greater fire frequency, higher temperatures, lower elevations, less rocky habitats and aspect (i.e. east-facing slopes had the least mortality). Conclusions: Our results show that W. cedarbergensis populations have declined significantly over the recorded period, with a pronounced decline in the last 30 years. Individuals that established in open habitats at lower, hotter elevations and experienced a greater fire frequency appear to be more vulnerable to mortality than individuals growing within protected, rocky environments at higher, cooler locations with less frequent fires. Climate models predict increasing temperatures for our study area (and likely increases in wildfires). If these predictions are realised, further declines in the species can be expected. Urgent management interventions, including seedling out-planting in fire-protected high elevation sites, reducing fire frequency in higher elevation populations, and assisted migration, should be considered.
Resumo:
Economic policy-making has long been more integrated than social policy-making in part because the statistics and much of the analysis that supports economic policy are based on a common conceptual framework – the system of national accounts. People interested in economic analysis and economic policy share a common language of communication, one that includes both concepts and numbers. This paper examines early attempts to develop a system of social statistics that would mirror the system of national accounts, particular the work on the development of social accounts that took place mainly in the 60s and 70s. It explores the reasons why these early initiatives failed but argues that the preconditions now exist to develop a new conceptual framework to support integrated social statistics – and hence a more coherent, effective social policy. Optimism is warranted for two reasons. First, we can make use of the radical transformation that has taken place in information technology both in processing data and in providing wide access to the knowledge that can flow from the data. Second, the conditions exist to begin to shift away from the straight jacket of government-centric social statistics, with its implicit assumption that governments must be the primary actors in finding solutions to social problems. By supporting the decision-making of all the players (particularly individual citizens) who affect social trends and outcomes, we can start to move beyond the sterile, ideological discussions that have dominated much social discourse in the past and begin to build social systems and structures that evolve, almost automatically, based on empirical evidence of ‘what works best for whom’. The paper describes a Canadian approach to developing a framework, or common language, to support the evolution of an integrated, citizen-centric system of social statistics and social analysis. This language supports the traditional social policy that we have today; nothing is lost. However, it also supports a quite different social policy world, one where individual citizens and families (not governments) are seen as the central players – a more empirically-driven world that we have referred to as the ‘enabling society’.
Resumo:
The genomic region containing the lactase (LCT) gene shows one of the strongest signals of positive selection in Europeans, detectable using a range of approaches including haplotype length, linked microsatellite variation and population-differentiation-based tests. Lactase is the enzyme that carries out the digestion of the milk sugar lactose. Its expression decreases at some point after the weaning period is over in most mammals and in around 68% of all living adult humans. However, in some humans, particularly those from populations with a history of dairying, lactase is expressed throughout adulthood. This trait is called lactase persistence (LP), and in people of European ancestry, it is associated with a single mutation (-13910*T). Evidence from the detection of dairy fat residues in potsherds, and allele frequencies in ancient DNA samples suggest that LP arose after dairying practices had developed. However, the reasons why LP may have been advantageous are still debated, and the respective contribution of demography and natural selection remains to be disentangled. This paper discusses various studies, from archaeology to population genetics, that have shed some light on the subject by investigating the evolution of LP in Europe.
Resumo:
The Autonomous Region of Castilla-La Mancha develops from the approval of the Spanish Constitution a whole executive and legislative branch to implement its policies on environmental protection. The new legislation (Law 9/1999, of 26 May) has pursued the conservation and the integral protection of the natural elements of the territory demanding to new criteria as such the environmental quality of ecosystems or the exceptional landscape. The spread and the declaration of new natural spaces have caused a double geographical and territorial model. First, natural spaces located in rural mountainous areas with depopulation and aging problems. And second, natural spaces situated in areas densely populated
Resumo:
This paper discusses some aspects of hunter-gatherer spatial organization in southern South Patagonia, in later times to 10,000 cal yr BP. Various methods of spatial analysis, elaborated with a Geographic Information System (GIS) were applied to the distributional pattern of archaeological sites with radiocarbon dates. The shift in the distributional pattern of chronological information was assessed in conjunction with other lines of evidence within a biogeographic framework. Accordingly, the varying degrees of occupation and integration of coastal and interior spaces in human spatial organization are explained in association with the adaptive strategies hunter-gatherers have used over time. Both are part of the same human response to changes in risk and uncertainty variability in the region in terms of resource availability and environmental dynamics.
Resumo:
En este artículo se presenta una visión panorámica de la situación actual del judaísmo así como de los principales problemas y desafíos que afronta en la actualidad. De manera especial se reflexiona sobre el concepto de identidad judía, pues son muchas y diferentes las respuestas a las preguntas ¿quién es judío? y ¿qué significa ser judío?
Resumo:
Bajo el paradigma de modernización y desarrollo norteamericano -y en un contexto de Guerra Fría-, durante la década de 1960 se adecuaron a la realidad chilena programas de control de natalidad que no sólo buscaron disminuir las altas tasas de mortalidad materno infantil, sino que además respondieron al proyecto de seguridad hemisférica norteamericana de contención a posibles revoluciones populares en países del Tercer Mundo.
Resumo:
Le but de cette thèse a consisté à comprendre les facteurs de la persévérance et de l’abandon scolaire des nouveaux arrivants haïtiens au Québec et à New York. La recension d’écrits a révélé une sous-documentation de la thématique en question. Toutefois, l’élaboration du cadre conceptuel nous a permis de mieux cerner la problématique, d’analyser et de synthétiser plusieurs approches théoriques dont les théories du rendement scolaire des immigrants (Rong et Brown, 2001 ; Warikoo et Carter, 2009 ; Xie et Greenman, 2011), l’approche bourdieusienne des capitaux (1979a, 1979b, 1980), le structuro-fonctionnalisme de Merton (1965) et le courant effets-écoles/ effets-enseignants (Crahay, 2000 ; Bressoux, 1994a). Nous avons également mis en évidence deux approches compréhensives à savoir l’interactionnisme (Weber, 1959 ; Boudon, 1979, 1994 ; Goffman, 1998 ; Garfinkel, 1967) et l’approche du rapport au savoir de l’équipe ESCOL (Rochex, 2002 ; Charlot, 2003) dans l’objectif de faire valoir le caractère relatif des conclusions d’une recherche qualitative qui priorise la subjectivité des participants dans l’analyse des faits sociaux. Dans cette recherche, nous avons interviewé onze participants à Montréal et à Brooklyn, parmi lesquels sept hommes et quatre femmes. Ils ont tous une expérience d’abandon scolaire au secondaire ou au secteur des adultes. Nous avons utilisé l’entretien semi-dirigé comme méthode de collecte d’information et l’analyse thématique est celle de l’analyse des données. L’analyse des données nous a permis de classer les informations fournies par les participants en cinq rubriques : capital économique, capital culturel, capital social, encadrement institutionnel et facteurs spécifiques. Ces cinq rubriques regroupent les facteurs de la persévérance et du décrochage scolaire évoqués par les participants de la recherche. La réalisation de cette thèse nous apporte un bon éclairage quant à notre tentative de comprendre la dynamique de l’abandon scolaire des jeunes et des jeunes adultes immigrants haïtiens de première génération au Québec et à New York, au secondaire et au secteur de l’éducation des adultes. Nous avons mis en relation les résultats de la recherche avec ceux des travaux que nous avons recensés dans la problématique et dans le cadre conceptuel de cette thèse. La synthèse de ces résultats nous a amené à faire une proposition d’éléments d’un modèle d’analyse que nous qualifions de « relance scolaire des nouveaux arrivants haïtiens au Québec et à New York ». L’analyse et la synthèse des facteurs émergents de la recherche, plus précisément des six thèmes qui composent la rubrique des facteurs spécifiques : facteurs démographiques, motivation personnelle, lacunes de base, facteurs affectifs, traits de personnalité et problèmes de comportement, nous ont permis d’élaborer un autre concept qui peut représenter une grande contribution à la persévérance scolaire des nouveaux arrivants haïtiens. Il s’agit de l’encadrement psycho-intégrationnel qui est une forme d’accompagnement dont les jeunes et les jeunes adultes nouveaux arrivants haïtiens pourront être bénéficiaires au début en vue d’un bon démarrage sur le plan socioéducatif et de leur persévérance scolaire au pays d’accueil. L’encadrement psycho-intégrationnel, consistera à mettre en relation certains faits psychologiques qui ont marqué la vie pré-migratoire des élèves jeunes et jeunes adultes d’origine haïtienne avec les faits sociaux qui peuvent influencer leur vie au pays d’accueil. C’est une forme d’assistance individuelle dont l’État, les institutions sociales d’intégration et l’école constitueront les principales structures de matérialisation. Les principaux intervenants, notamment les psychologues, les travailleurs sociaux et les anthropo-sociologues se chargeront de comprendre et d’orienter les nouveaux arrivants quant au nouveau comportement à adopter pour une meilleure évolution sur les plans socio-culturel, professionnel et économique. Mots clés : Persévérance scolaire, relance scolaire, immigrants haïtiens, première génération, nouveaux arrivants.
Resumo:
Thesis (Master's)--University of Washington, 2016-08
Resumo:
Thesis (Ph.D.)--University of Washington, 2016-08
Resumo:
The period between offspring birth and recruitment into the breeding population is considered one of the least understood components of animal life histories. Yet, examining this period is essential for studies of parental care, dispersal, demography, and life histories. Studies of the pre-reproductive period are particularly few in tropical regions, where the organization of life histories are predicted to differ compared to northern hemisphere species. For my dissertation I used radio-telemetry, mark-resighting, and field observations to study the pre-reproductive period in a Neotropical bird, the western slaty-antshrike (Thamnophilus atrinucha), in Panama. First, I found that parental care after offspring left the nest (the post-fledging period) was greater than care during the nestling period. Prolonged care resulted in a clear trade-off for parents as they did not nest again until fledglings from the first brood were independent. Parents fed offspring for a prolonged duration during the post-fledging period and higher post-fledging survival was observed compared to many northern hemisphere species. Second, I observed that offspring that remained with parents for longer periods on the natal territory had higher survival both while on the natal territory and after dispersal compared to those dispersing earlier. Parental aggression towards offspring increased with offspring age and offspring dispersed earlier when parents renested. Contrary to other family living species, only a small proportion of antshrike offspring remained on the natal territory until the following year and all dispersed to float. Floating is when juveniles wander within other breeding pairs’ territories. These results suggest that the benefits of delayed dispersal declined with offspring age and with renesting by parents. Third, I observed that survival during the dependent period and first year was greater in slaty antshrikes compared to that of northern hemisphere species. Pre-reproductive survival relative to adult survival was equal or greater than that observed in northern hemisphere species. The date offspring left the nest, mass, and age at dispersal influenced offspring survival, whereas offspring sex and year did not. Relatively high survival during the pre-reproductive period coupled with comparatively low annual productivity clarifies how many tropical species achieve replacement. High juvenile survival appears to obtain from extended post-fledging parental care, delayed dispersal, low costs of dispersal, and a less seasonal environment. Lastly, I experimentally manipulated begging at the nest to examine changes in parental behavior. Under elevated begging, parents increased provisioning rates and reduced the time between arrival to the nest and feeding of nestlings, potentially to reduce begging sounds. Furthermore, parents switched to preferentially feed the closest offspring during the begging treatment. This suggests parents either allowed sibling competition to influence feeding decisions, or feeding the closer nestling increased the efficiency of provisioning. In summary, I found that slaty antshrikes have delayed age at reproduction, higher post-fledging and first year survival, extended post-fledging parental care, equal or greater pre-reproductive survival relative to adult survival, and delayed dispersal compared to many northern hemisphere passerines. These results suggest that this tropical species has a strategy of high investment into few offspring. Furthermore, reproductive effort is equal or greater at least in slaty antshrikes compared to northern hemisphere species, suggesting that the latitudinal gradient in clutch size is not explained by a gradient in reproductive effort.
Resumo:
This thesis draws together all of the data on Roman-period leather from northern Britain and conducts a cohesive assessment of past research, current questions and future possibilities. The study area comprises Roman sites on or immediately to the south of Hadrian’s Wall and all sites to the north. Leather has been recovered from 52 Roman sites, totalling at least 14,215 finds comprising manufactured goods, waste leather from leatherworking and miscellaneous/unidentifiable material. This thesis explores how leather and leather goods were resourced, processed, manufactured and supplied across northern Britain. It considers the potential of inscriptions and stamps to provide insights into the leather trade. It also considers the contribution that the study of footwear might make to our understanding of the demography of Roman settlements, shedding light in particular on evidence which suggests that military communities may have been more diverse than previously thought, and that there were women and children living on the northern fringes of the empire long before the Antonine Wall and its civilian communities were established.
Resumo:
33 p.
Resumo:
Tese de Doutoramento, Ciências do Ambiente (Ecologia), 30 de Julho de 2013, Universidade dos Açores.
Resumo:
This study consisted in the comparison of the prevalence of Helicobacter pylori (H. pylori) present in the stomach and in saliva of a sample of Portuguese adolescents and the assessment of the association between H. pylori infection with socio-demographic variables and prevalence of dental caries.