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241.
Protecting riparian corridors is a commonly applied environmental policy in urban landscapes. However, empirical data demonstrating their efficacy for biodiversity conservation outcomes is scarce. In this study we investigated whether riparian corridor width influences the diversity and community structure of ant (Hymenoptera: Formicidae) and vascular plant assemblages therein. Eighteen corridors of differing widths were selected from within the Ku-ring-gai Local Government Area, Sydney Australia. Ants were sampled using pitfall traps positioned within rectangular vegetation transects (30 × 10 m). Both ant and plant species richness, when standardised for sampling effort, were unrelated to riparian corridor width. However, significant compositional differences between sites were evident with increased width up to ~50 m. Narrow corridors contained greater abundances of opportunistic ant species and higher proportions of exotic plants. We interpret this to be the result of the greater disturbance/edge influence derived from adjacent upland urban environments. Site beta diversity did not increase with corridor width, suggesting that the exclusion of novel upslope habitats in narrow riparian corridors is not a significant cause of community assemblage modification at these sites. To minimise the impact of deleterious edge effects on ant fauna, environmental managers should seek to retain riparian corridors wider than ~50 m. However, we observed substantial between-site variability of biotic assemblages, irrespective of corridor width. Therefore we recommend that environmental management practice needs to take a catchment-wide approach and consider other parameters that may contribute to riparian health so as to optimise the protection of riparian biodiversity.  相似文献   
242.
All children in the Czech Republic have the legal right to primary education, regardless of nationality and legal status. This article is based on a study of refugee children and their educational situation. The study reveals that refugee students in the Czech Republic are not benefiting fully from this fundamental right and that their educational future is in jeopardy. The study identified six major barriers to full participation and educational benefits. Finally, a plan of action to overcome barriers is put forward. Key ingredients are effective information transfer among state agencies, non‐governmental organizations, parents, children and schools.  相似文献   
243.
This paper considers early educational interventions aimed at preventing school failure. It begins with a typology of prevention and intervention, then goes on to consider four specific examples of preventive interventions all aimed at avoiding or alleviating academic failure at school. (1) The High Scope pre-school programme for disadvantaged children aimed at providing a ‘better start at school'. (2) Reading Recovery, a targeted intervention aimed at getting children who show early reading difficulties ‘back on course'. (3) A Focused Literacy Programme for improving the reading of all children in disadvantaged neighbourhoods of the inner city. (4) ‘Parent involvement' programmes to improve the reading of all children in primary school through support for literacy at home. Each of the intervention strategies is described and criticised in terms of effectiveness, acceptability and generalisation. Copyright © 1999 John Wiley & Sons, Ltd.  相似文献   
244.
Neural correlates of anticipatory and reactive saccades were studied in 4‐month‐old infants by recording high‐density event‐related potentials. Infants were presented with a fixed sequence of stimulus presentation to which they rapidly showed anticipatory saccades, as well as continuing with some reactive (stimulus‐driven) saccades. As in a previous study, no clear evidence was found for adultlike, saccade‐related potentials, although some presaccadic differences between reactive and anticipatory saccades were observed. Infants also showed different stimulus offset‐related effects preceding the 2 types of trials with a right‐frontal positivity when an anticipatory look follows, but only left‐frontal positivity when a reactive saccade follows.  相似文献   
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Assume independent random samples are drawn from two populations which are exponentially distributed with unknown location parameters and a common known scale parameter. We want to estimate the maximum and the minimum of the unknowo location paremeters. In this paper several estimators are proposed which are better than the natural estimations in terms of absolute bias and /or meaqn squared error.  相似文献   
248.
We test the mediated effects of participation in employee involvement (EI) programs on employee desires for union involvement in the future development and diffusion of EI and the perceived durability of an EI program as a possible moderator of these effects. Results indicate that participants developed more positive attitudes toward the EI program than nonparticipants and, in turn, these attitudes were related to higher desires for union involvement in EI. Additionally, volunteers developed more positive attitudes toward the EI program than nonvolunteers and, in turn, these attitudes were related to higher desires for union involvement in EI. However, the relationship between attitudes toward EI and desires for union involvement in EI was significantly less positive for participants who viewed the EI program as durable.  相似文献   
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