We present a new approach to the theory of magnetohydrodynamic equilibria with anisotropic pressure, magnetic shear and translational/rotational invariance. This approach involves combining two ...existing formalisms in order to eliminate their individual weaknesses. The theoretical aspects of the method are explored in detail along with numerical solutions which make use of the method. Eventually, this method could be applied to model various plasma systems, such as planetary magnetospheres.
Population monitoring is an essential part of evaluating the effectiveness of management interventions for conservation. Coastal breeding aggregations of marine vertebrate species that come ashore to ...pup or nest provide an opportunistic window of observation into otherwise widely dispersed populations. Green turtle (Chelonia mydas) nesting on the north and west coasts of northern Cyprus has been monitored consistently and exhaustively since 1993, with an intensive saturation tagging programme running at one key site for the same duration. This historically depleted nesting population is showing signs of recovery, possibly in response to nest protection approaching two decades, with increasing nest numbers and rising levels of recruitment. Strong correlation between year‐to‐year magnitude of nesting and the proportion of new breeders in the nesting cohort implies that recruitment of new individuals to the breeding population is an important driver of this recovery trend. Recent changes in fishing activities may be impacting the local juvenile neritic stage, however, which may hinder this potential recovery. Individuals returning to breed after two years laid fewer clutches than those returning after three or four years, demonstrating a trade‐off between remigration interval and breeding output. Average clutch frequencies have remained stable around a median of three clutches a year per female despite the demographic shift towards new nesters, which typically lay fewer clutches in their first season. We show that where local fecundity has been adequately assessed, the use of average clutch frequencies can be a reliable method for deriving nester abundance from nest counts. Index sites where individual‐based monitoring is possible will be important in monitoring long‐term climate driven changes in reproductive rates.
In many polyandrous species, the second male to mate with a female has fertilization priority. Strategic mechanisms generating this pattern tend to involve facultative increases in ejaculate size by ...informed males. Here we suggest a novel mechanism to generate second male precedence in internal fertilizers, based on the established fact that the female site of insemination is hostile to sperm, and that non-sperm components of the ejaculate frequently act to ameliorate these hostile conditions. We suggest that in species where female remating is frequent and rapid, second male sperm precedence may be due to the prior buffering of the female tract by previous males’ ejaculates. In this scenario, second male costs are lower due to reduced sperm mortality and/or the redundancy of seminal fluid. Contrary to many classical predictions, second males may gain a paternity advantage despite investing less in an ejaculate.
Assessing wave energy effects on biodiversity: the Wave Hub experience Witt, M. J.; Sheehan, E. V.; Bearhop, S. ...
Philosophical transactions - Royal Society. Mathematical, Physical and engineering sciences/Philosophical transactions - Royal Society. Mathematical, physical and engineering sciences,
01/2012, Letnik:
370, Številka:
1959
Journal Article
Recenzirano
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Marine renewable energy installations harnessing energy from wind, wave and tidal resources are likely to become a large part of the future energy mix worldwide. The potential to gather energy from ...waves has recently seen increasing interest, with pilot developments in several nations. Although technology to harness wave energy lags behind that of wind and tidal generation, it has the potential to contribute significantly to energy production. As wave energy technology matures and becomes more widespread, it is likely to result in further transformation of our coastal seas. Such changes are accompanied by uncertainty regarding their impacts on biodiversity. To date, impacts have not been assessed, as wave energy converters have yet to be fully developed. Therefore, there is a pressing need to build a framework of understanding regarding the potential impacts of these technologies, underpinned by methodologies that are transferable and scalable across sites to facilitate formal met a-analysis. We first review the potential positive and negative effects of wave energy generation, and then, with specific reference to our work at the Wave Hub (a wave energy test site in southwest England, UK), we set out the methodological approaches needed to assess possible effects of wave energy on biodiversity. We highlight the need for national and international research clusters to accelerate the implementation of wave energy, within a coherent understanding of potential effects—both positive and negative.
There is substantial evidence that genetic variation, at both the level of the individual and population, has a significant effect on behaviour, fitness and response to toxicants. Using DNA ...microsatellites, we examined the genetic variation in samples of several commonly used laboratory strains of zebrafish, Danio rerio, a model species in toxicological studies. We compared the genetic variation to that found in a sample of wild fish from Bangladesh. Our findings show that the wild fish were significantly more variable than the laboratory strains for several measures of genetic variability, including allelic richness and expected heterozygosity. This lack of variation should be given due consideration for any study which attempts to extrapolate the results of ecotoxicological laboratory tests to wild populations.
Objective: Our purpose was to investigate the efficacy and safety of 0.1% topical tacrolimus in erosive or ulcerative oral lichen planus. Methods: This was an open-label, noncomparative study ...conducted in an outpatient oral medicine unit in London, United Kingdom. The study covered an 8-week period with a 22-week follow-up after cessation of therapy. Nineteen patients, aged 28 to 87 years with biopsy-proven oral lichen planus refractory to, or dependent on, systemic immunosuppressive agents, were enrolled. Seventeen patients (89%) completed the study. Application of 0.1% tacrolimus was administered to all symptomatic oral mucosal lesions. Clinical review took place 1, 3, 5, 7, and 8 weeks after commencing therapy. Alleviation of symptoms was evaluated by using a visual analogue scale as well as the McGill Pain and Oral Health Impact profile questionnaires. The extent of the oral mucosal erosion or ulceration was directly measured by the same clinician at all visits. Safety assessments included monitoring of adverse events, complete blood cell count, renal and hepatic clinical chemistry, and tacrolimus blood concentrations. Results: Tacrolimus caused a statistically significant improvement in symptoms within 1 week of commencement of therapy. A mean decrease of 73.3% occurred in the area of ulceration over the 8-week study period. Local irritation (in 6 subjects, 35%) was the most commonly reported adverse effect. Laboratory values showed no significant changes with time. Therapeutic levels of tacrolimus were demonstrated in 8 subjects but were unrelated to the extent of oral mucosal involvement. Thirteen of 17 patients suffered a relapse of oral lichen planus within 2 to 15 weeks of cessation of tacrolimus therapy. Conclusion: Topical tacrolimus is effective therapy for erosive or ulcerative oral lichen planus. (J Am Acad Dermatol 2002;46:35-41.)
► The effect of future climate scenarios on surface water and groundwater resources was assessed. ► The associated risk to water dependent ecosystems was inferred. ► The greatest impact was projected ...for a dry future climate scenario. ► Reduction in ecologically significant river flow rates is particularly large. ► Groundwater dependent ecosystems are under high and severe risks over 20% of their current area.
The effect of future climate scenarios on surface water and groundwater resources has been shown to have a consequent impact on water-dependent ecosystems. A regional-scale analysis of changes in water resources as a result of changing climate was undertaken in south-western Australia; a region with a large number of nationally and internationally recognised water-dependent ecosystems. The paper examines the potential environmental impacts of a substantial reduction in rainfall and an increase in temperature as projected by global climate models (GCMs) on river and groundwater-dependent terrestrial vegetation by 2030.
Climate change effects on environmentally significant flow regimes were evaluated by applying the climate projections from 15 GCMs under three global warming ‘scenarios to rainfall–runoff and groundwater models. It was estimated that under a dry future climate scenario, the frequency of river flow rates important for ecological communities is likely to be reduced by up to 2months per year, which is likely to cause a significant level of stress to ecological communities. Additionally, the duration of no-flow periods may increase by more than 120days in some streams. Under a dry future climate scenario, groundwater-dependent vegetation is projected to be at a high risk in over 19% of its current habitat area. Water-dependent ecosystems are also projected to be affected by an increase in groundwater abstraction.
The results indicate that the projected impacts of future climate conditions are not likely to be uniform across the region but overall they could cause a continuing threat to water-dependent ecosystems. The implementation of water management plans should place particular emphasis on the ecological water requirements in 6 of the 13 river catchments in south-western Australia and in areas where groundwater abstraction is high. The climate projections and ecological impacts are a continuation of the trends that have taken place in the past three decades.
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