996 resultados para Seligman, Martin E. P
Resumo:
Estudi elaborat a partir d’una estada a l’ Albert Ludwigs Universität, Alemanya, entre els mesos de maig i octubre del 2006.El tema del temps és extremadament important per a Martin Heidegger. I el seu pensament al respecte no pot ésser comprès adequadament si no tenim en compte la gran influència que diversos filòsofs hi van exercir. Aristòtil i Agustà són elsmés destacats, tal i com el propi Heidegger afirma a les seves lliçons marburgueses del semestre d’estiu de 1927. Sense elles, no es pot entendre el complex entramat terminològic ni les idees fonamentals sobre la temporalitat. Idees que apareixen publicades en diverses obres seves. El transfons filosòfic de cadascun d’aquests escrits és, en part, el concepte aristotèlic o Agustina de temps. Ésser i temps no és una obra que neixi del no res com a producte de la necessitat de l’autor de consolidar el seu currÃculum en vistes a una plaça docent, sinó que la publicació durant aquests darrers anys de les seves lliçons i altres escrits menors permeten observar com es va gestant la manera en que Heidegger entendrà el concepte de temps que es reflexa en aquest tractat, i que, com ja s’ha dit, es sustenta en les idees d’Aristòtil i d’Agustà al respecte. S’ha mostrat també de quina manera Heidegger porta a la prà ctica la reconstrucció fenomenològica proposada pel que va ser el seu mentor, Husser, i com recondueix els conceptes fonamentals d’ambdós filòsofs, incorporant-los a la seva particular manera d’entendre el temps.
Resumo:
Directional selection for parasite resistance is often intense in highly social host species. Using a partial cross-fostering experiment we studied environmental and genetic variation in immune response and morphology in a highly colonial bird species, the house martin (Delichon urbica). We manipulated intensity of infestation of house martin nests by the haematophagous parasitic house martin bug Oeciacus hirundinis either by spraying nests with a weak pesticide or by inoculating them with 50 bugs. Parasitism significantly affected tarsus length, T cell response, immunoglobulin and leucocyte concentrations. We found evidence of strong environmental effects on nestling body mass, body condition, wing length and tarsus length, and evidence of significant additive genetic variance for wing length and haematocrit. We found significant environmental variance, but no significant additive genetic variance in immune response parameters such as T cell response to the antigenic phytohemagglutinin, immunoglobulins, and relative and absolute numbers of leucocytes. Environmental variances were generally greater than additive genetic variances, and the low heritabilities of phenotypic traits were mainly a consequence of large environmental variances and small additive genetic variances. Hence, highly social bird species such as the house martin, which are subject to intense selection by parasites, have a limited scope for immediate microevolutionary response to selection because of low heritabilities, but also a limited scope for long-term response to selection because evolvability as indicated by small additive genetic coefficients of variation is weak.
Resumo:
In altricial birds post-fledging survival is usually positively related to nestling body mass. A large number of studies have shown that the latest hatched chick is the more likely to die, even if food is abundant. Here we suggest that ectoparasites may be a key factor in the evolution and the maintenance of the establishment of weight hierarchies within broods. We prepose the hypothesis that weight hierarchies within broods may be adaptive if the chick in poor condition is the one with the least efficient immune system within a nest. In this case parasites would preferentially feed on such a "tasty chick", because it would allow high reproductive rates for the parasites, without negatively affecting the survival of the other nestlings. This could prevent entire nest failure of the brood or allow the other chicks to grow more efficiently. This hypothesis was investigated in a colony of house martins Delichon urbica. We predicted that immunocompetence was positively correlated with body condition, and that nestlings dying before hedging should have lower immune responses when challenged with an antigen. T-cell immune response to an experimentally injected antigen was strongly positively related to body condition. Non-surviving chicks had low body condition and a weak immune response. The implications of these results are discussed in the context of the adaptive significance of hatching asynchrony.
Resumo:
[Vente. Estampes. 1855-02-05. Paris]
Resumo:
Esta pesquisa tem como ponto de partida experiências compartilhadas com portadores de diabetes mellitus. A fenomenologia existencial de Martin Heidegger possibilitou a apreensão dos momentos vividos por esses seres. Entrevistou-se, em seus domicÃlios, oito pessoas que residem em Bandeirantes, cidade situada no norte do Paraná, e que tiveram alguma complicação podológica decorrente da doença, no perÃodo de fevereiro a agosto de 2007. O estudo teve como objetivo compreender suas vivências ao experienciarem uma complicação podológica em seu existir-no-mundo. Para desvelar a linguagem dos sujeitos, empregou-se a seguinte questão norteadora: Como é, para você, viver com uma complicação podológica desenvolvida por consequência do seu diabetes mellitus? Da linguagem dos sujeitos emergiu o tema: O ser-aà e o cuidado inautêntico. Os resultados obtidos revelam a importância de oferecer um cuidado holÃstico ao Ser que vivencia esta facticidade, pois muitas vezes a subjetividade do cuidado fica absorvida pela massificação das regras e normas institucionais.