207 resultados para UV protection


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This article reports the findings of the second part of a two-part research project examining the potential for social workers to make changes in their work with families and children. While social workers in the United Kingdom have been encouraged to shift from a child protection to a child welfare orientation in their practice, such changes have been hampered by professional and organisational concern to manage risk. The research explores the influence of a child protection orientation on practice in child welfare cases. The findings, from two file analyses and interviews with twenty-six social workers, indicate that such an influence is indeed apparent. This is evidenced in two ways; firstly patterns of practice in child welfare cases are similar to those in child protection cases. Secondly, while the majority of social workers express an attitudinal desire to move towards a child welfare orientation, they still prioritise the management of risk in their practice. It is argued that social workers need permission from their employing organisations to make changes in their practice. This, in turn, requires such organisations to state clear goals in line with a child welfare orientation and develop holistic strategies to achieve these.

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Field-collected specimens of three species of Laminaria and three species of subtidal red algae (Delesseria sanguinea, Plocamium cartilagineum and Phyllophora pseudoceranoides) were exposed to natural summer sunlight on Helgoland (southern North Sea) for up to 4 h at 15 °C. Dark-adapted variable fluorescence (Fv : Fm) was measured immediately after these treatments, and following 6, 24 and 48 h of recovery in moderate irradiances of white light. The response of plants to the full spectrum of natural sunlight was compared with that to PAR alone, UV-A + visible, UV-A + UV-B, or UV-A alone. The Fv : Fm values of all species were reduced to minimal values after 4 h in all of these treatments, but those of the more resistant species (Laminaria spp. and P. pseudoceranoides) were higher after shorter exposures to UV radiation alone than to PAR with or without UV. The recovery of Fv : Fm in all species was also more rapid in the two treatments that contained UV radiation alone than in those that included PAR. These results suggest that it is the high irradiances of PAR in natural sunlight which are responsible for the photoinhibition of photosynthesis of subtidal seaweeds and that the current ambient irradiances of UV radiation (either UV-B or UV-A) in northern temperate latitudes would not contribute significantly to this photoinhibition.