138 resultados para Extreme values
Resumo:
We present a model of the evolution of identity via dynamic interaction between the choice of education and the transmission of values in a community from parents to children, when parents care about the preservation of their traditional community values, different from the values of the host society. We compare the educational and socioeconomic outcomes in different scenarios (melting pot versus multiculturalism). If schooling shifts children’s identity away from their parents’ values, parents may choose lower levels of education for their children, at the cost of reducing their future earnings. We show how this effect can be attenuated and reversed when the school or, indeed, the host society are willing to accommodate the values of the community and/or to adjust to these values; otherwise the community gradually becomes alienated. This approach may be applied to the analysis of temporal changes in values and attitudes in a community of immigrants, as well as ethnic, religious, or other minority groups.
Resumo:
Drought events are projected to increase in frequency and magnitude, which may alter the composition of ecological communities. Using a functional community metric that describes abundance, life history traits and conservation status, based upon Grime’s CSR (Competitive-Stress tolerant-Ruderal)¬ scheme, we investigated how British butterfly communities changed during an extreme drought in 1995. Throughout Britain, the total abundance of these insects had a significant tendency to increase, accompanied by substantial changes in community composition, particularly in more northerly, wetter sites. Communities tended to shift away from specialist, vulnerable species, and towards generalist, widespread species and, in the year following, communities had yet to return to equilibrium. Importantly, heterogeneity in surrounding landscapes mediated community responses to the drought event. Contrary to expectation, however, community shifts were more extreme in areas of greater topographic diversity, whilst land-cover diversity buffered community changes and limited declines in vulnerable specialist butterflies.
Resumo:
The need for a reconsideration of resilience from both a positive and a normative point of view can be discussed using some of the lessons and conclusions drawn from individual resilience studied by psychologists in an educational context. The main point made in this article is that unless we want to approach resilience as a feature which is exogenously given in each population and society and whose dynamics, if any, are not subject to deliberate actions and policies, we need a framework for the evaluation of resilience as a social good. Relying on the hope that resilience is necessarily built in our societies as a force guaranteeing convergence to a socially desirable point of social evolution may be too optimistic and even counterproductive, because it may lead us to an inefficient or biased political and regulatory decision making. When the effect of policies and actions at a national or international level take into account the dynamic effect of such actions on resilience itself, one cannot blindly rely on the goodness of the process any more. This is mainly because resilience is not uniformly embodied in all societies and it does not have a globally positive social value by itself. The issue of socially valuing the options available beyond market-price valuations becomes fundamental in this context.