991 resultados para environmental guidelines


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Why generalist and specialist species coexist in nature is a question that has interested evolutionary biologists for a long time. While the coexistence of specialists and generalists exploiting resources on a single ecological dimension has been theoretically and empirically explored, biological systems with multiple resource dimensions (e.g. trophic, ecological) are less well understood. Yet, such systems may provide an alternative to the classical theory of stable evolutionary coexistence of generalist and specialist species on a single resource dimension. We explore such systems and the potential trade-offs between different resource dimensions in clownfishes. All species of this iconic clade are obligate mutualists with sea anemones yet show interspecific variation in anemone host specificity. Moreover, clownfishes developed variable environmental specialization across their distribution. In this study, we test for the existence of a relationship between host-specificity (number of anemones associated with a clownfish species) and environmental-specificity (expressed as the size of the ecological niche breadth across climatic gradients). We find a negative correlation between host range and environmental specificities in temperature, salinity and pH, probably indicating a trade-off between both types of specialization forcing species to specialize only in a single direction. Trade-offs in a multi-dimensional resource space could be a novel way of explaining the coexistence of generalist and specialists.

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Developed from Partnerships in Caring (2000)

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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.

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This document is designed to provide guidelines to professionals working with people who are HIV positive where the person living with HIV is placing other people at risk of infection through unprotected sexual intercourse or needle sharing, without informing his/her partner of the risk Download the Report here

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Benzodiazepines are one of the most widely used prescription medicinal products in the world. Benzodiazepines may be prescribed safely in the short-term and are a highly effective treatment for anxiety, insomnia and some forms of epilepsy and spasticity. Benzodiazepines are only indicated when the disorder is severe, disabling or subjecting the individual to extreme distress. Dependence is now recognised as a significant risk in patients receiving treatment for longer than one month and the practitioner has to be conscious of this when evaluating the relative benefits and risks of continued prescription. Download document here

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This revised report on immunisation guidelines for Ireland has been prepared with the assistance of an active committee from associated disciplines in Paediatrics, Infectious Diseases, General Practice and Public Health. The report itself is designed to be simple and concise and of course does not claim to contain all information on any pharmacological material. It does, however, give the current information and guidelines concerning immunisation. Vaccines are continually evolving and guidelines will obviously change given the nature of these developments. This is a tribute to the pharmaceutical industry who invest so much money in research and development in this particular field. Download document here

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Food & Nutrition Guidelines for Primary Schools The Government has identified school children as one group to be given priority during the planning and delivery of programmes and initiatives for good health throughout life. In the Governmentâ?Ts National Health Promotion Strategy 2000/2005, the two major objectives for children are: Click here to download PDF 458kb

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Guidelines on the Provision of Structured Car Parking Facilities at Acute Hospitals These guidelines have been developed to ensure that any future developments for car parking facilities are consistent with Department policy and deliver value for money. They are intended to assist acute hospitals in ensuring that best practice is followed at all stages in the provision and management of structured car parking facilities. Click here to download PDF 23kb

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The Minister for Health’s Strategy for effective health care in the 1990s has emphasised quality of service as one of its key principles.  Within the medical sphere, almost no other field has developed and continues to expand as rapidly as that of cancer biology and treatment.  Cytotoxic therapies are a major part of these developments. The Cancer Strategy has highlighted the importance of these drugs in the treatment of cancers. Download the Report here

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The immature stages of Ochlerotatus albifasciatus develop in temporary pools. The present study aims at evaluating the seasonal dynamics of the aquatic stages of this mosquito, also analyzing the relationship among their presence and breeding success to some relevant climatic and environmental variables in the ephemeral rain pools of an urban park. Nineteen cohorts of O. albifasciatus that developed synchronously after rain events were recorded in all seasons. The proportions of mosquito-positive pools were significantly higher during the fall-winter period than in the spring-summer months (p < 0.001). The presence of this mosquito species was positively related to the amount of rain (p < 0.001), whereas negatively correlated to air temperature (p < 0.05) within a 5.2 to 29.7ºC range. The distribution of the number of cohorts per pool throughout the year was grouped (variance/mean: 3.96), indicating that these habitats were not equally suitable as breeding sites. The immature stages of O. albifasciatus were detected in pools belonging to all of the categories of surface area, depth, duration, vegetation cover, and insolation. However, the proportion of pools where immature mosquitoes were detected was positively and significantly related to surface, depth, duration, and vegetation cover. On the other hand, the proportion of mosquito-positive pools was higher at an intermediate insolation degree. Our results suggest that although preimaginal stages were present in all seasons, high temperatures may be unfavorable to larval development, and substrate vegetation may regulate water temperature. The positive relationship between the proportion of mosquito-positive pools and pool size and duration might reflect a strategy of O. albifasciatus to accomplish immature development.