870 resultados para Global change and terrestrial ecosystems
Resumo:
Recent research in Australia and overseas has suggested that we are witnessing a convergence of men's and women's time on domestic labour activities. But there is disagreement about whether this is due to women reducing their time on housework or men increasing their time on housework. This article addresses these issues using national survey data collected in Australia in 1986, 1993 and 1997. The results show some changes in the proportional responsibilities of men and women in the home with men reporting a greater share of traditional indoor activities. But overall both men and women are spending less time on housework. In particular, women's time on housework has declined by six hours per week since 1986. Hence, while the gender gap between men's and women's involvement in the home is getting smaller, it is not the result of men increasing their share of the load, but is due to the large decline in women's time spent on domestic labour. There is also evidence of change in the relationship. between paid and unpaid work for women. Women's hours of,paid labour had a greater impact on their involvement in domestic labour in 1997 compared to a decade earlier. The article concludes that women's increased labour force involvement in combination with changing patterns and styles, of consumption is leading to some changes in the gender-division:of household labour, but not in the direction anticipated by earlier commentators on the domestic division of labour.
Resumo:
Mangroves are often described as a group of plants with common features and common origins based mostly on their broad distributional patterns, together with an erroneous view of comparable abilities in long-distance dispersal. However, whilst mangroves have common needs to adapt to rigorous environmental constraints associated with regular seawater inundation, individual taxa have developed different strategies and characteristics. Since mangroves are a genetically diverse group of mostly flowering plants, they may also have evolved at quite different geological periods, dispersed at different rates from different locations and developed different adaptive strategies. Current distributions of individual taxa show numerous instances of unusual extant distribution which demonstrate finite dispersal limitations, especially across open water. Our preliminary assessment of broad distribution and discontinuities reveals important patterns. Discontinuities, in the absence of current dispersal barriers, may be explained by persistent past barriers. As we learn more about discontinuities, we are beginning to appreciate their immense implications and what they might tell us about past geological conditions and how these might have influenced the distribution and evolution of mangroves. In this article, we describe emerging patterns in genetic relationships and distributions based on both current knowledge and preliminary results of our studies of molecular and morphometric characteristics of Rhizophora species in the Indo West Pacific region.
Resumo:
Two experiments investigated the effects of the sensory modality of the lead and of the blink-eliciting stimulus during lead stimulus modality change on blink modulation at lead intervals of 2500 and 3500 ins. Participants were presented with acoustic, visual, or tactile change stimuli after habituation training with lead stimuli from the same or a different sensory modality. In Experiment 1, latency and magnitude of the acoustic blink were facilitated during a change to acoustic or visual lead stimuli, but not during a change to tactile lead stimuli. After habituation to acoustic lead stimuli, blink magnitude was smaller during tactile change stimuli than during habituation stimuli. The latter finding was replicated in Experiment 2 in which blink was elicited by electrical stimulation of the trigeminal nerve. The consistency of the findings across different combinations of lead stimulus and blink-eliciting stimulus modalities does not support a modality-specific account of attentional blink modulation. Rather, blink modulation during generalized orienting reflects modality non-specific processes, although modulation may not always be found during tactile lead stimuli. (C) 2002 Elsevier Science B.V. All rights reserved.