3,045 research outputs found
Basking shark hotspots on the West Coast of Scotland: Key sites, threats and implications for conservation of the species
Copyright © Scottish Natural Heritage 2009.The Wildlife Trusts’ Basking Shark Project conducted effort-corrected line transect surveys for the basking shark (Cetorhinus maximus) along the west coast of Scotland between 2002- 2006. A total of 11,179km of linear transects consisting of 956 hours duration were covered, and a total of 593 sharks were recorded whilst on transect. The project aimed to establish whether key sites (hotspots) existed for the species within the overall region, where significant numbers of sharks could be seen at the surface on a regular basis. This information could then be used to develop practical means of protecting surface swimming sharks at such sites, such as educational maps of the hotspot sites for distribution to leisure and commercial boat users, and to inform future developments within the marine environment e.g. fisheries and renewable energy developments.The project enjoyed the support of many Organisations, both financially and in spirit. These
include Natural England, The Wildlife Trusts, WWF-UK, Earthwatch Institute (Europe), The
Born Free Foundation, The Shark Foundation (Hai Stiftung), The Shark Trust, the Marine
Conservation Society, the Heritage Lottery Fund, the National Express Group, the Save Our
Seas Foundation, Volvo Ocean Adventure, the Esmee Fairbairn Foundation, and Canon
(UK). Their support was invaluable
Microlensing planets in M22: free-floating or bound?
We use detailed numerical simulations and theoretical estimates to show that,
if confirmed, the unusually brief microlensing events observed by Sahu et al.
(2001) in the field of the globular cluster M22 might be explained as a result
of microlensing by a population of clustered MACHOs, a dark cluster or RAMBO,
not associated with the globular cluster. If real, this dark cluster would be
located between M22 and the Galactic bulge and could include at least
substellar members with a typical size of 1-3 pc. Bound planets in wide or/and
eccentric orbits are also able to reproduce the observed microlensing
behaviour, but only if multiplanet systems (including large Kuiper-belt-like
objects) are abundant, although, our calculations argue against the latter
scenario as the ionization rate in M22 is very high. Dynamically ejected or
lone planets are, in principle, incompatible with the observational findings as
they either escape their parent cluster in a relatively short time-scale after
ejection or segregate toward the outskirts of the cluster. We discuss
additional implications of the dark cluster scenario, including the existence
of a population of RAMBOs toward the Galactic bulge.Comment: 6 pages, 1 Postscript figure, LaTeX, uses A&A macros, submitted to
A&A Main Journa
Predicting the impacts of climate change on a globally distributed species: the case of the loggerhead turtle
© Company of Biologists. Post print version deposited in accordance with SHERPA RoMEO guidelines. The definitive version is available at: http://jeb.biologists.org/content/213/6/901.shortMarine turtles utilise terrestrial and marine habitats and several aspects of their life history are tied to environmental features that are altering due to rapid climate change. We overview the likely impacts of climate change on the biology of these species, which are likely centred upon the thermal ecology of this taxonomic group. Then, focusing in detail on three decades of research on the loggerhead turtle (Caretta caretta L.), we describe how much progress has been made to date and how future experimental and ecological focus should be directed. Key questions include: what are the current hatchling sex ratios from which to measure future climate-induced changes? What are wild adult sex ratios and how many males are necessary to maintain a fertile and productive population? How will climate change affect turtles in terms of their distribution
Pinnipeds, people and photo identification: the implications of grey seal movements for effective management of the species
This is the author accepted manuscript. The final version is available from Cambridge University Press via the DOI in this record.Grey seals (Halichoerus grypus) of the North-east Atlantic are protected at designated European Marine Sites (Special Areas of Conservation, SACs) typically during their reproductive periods and in the UK at Sites of Special Scientific Interest (SSSI). As a mobile marine species, grey seals spend other parts of their annual life cycle in non-designated habitat. There is limited information on individual grey seal movements in south-west England. Citizen science photo identification (PID) revealed the movements of 477 grey seals at a regional scale (54 haul-outs up to 230 km apart) for over a decade. Reconstructed movements showed considerable individual variability. Four SACs were linked to up to 18 non-designated sites and two SSSIs in Cornwall were linked to a maximum of 41 non-designated sites. Observations support the value of existing SSSIs at both the well-connected West and North Cornwall sites. Thirteen Marine Protected Areas (MPAs) were visited by grey seals from four SACs and two SSSIs in Cornwall. As a mobile species, grey seals could be included in English MPA management plans. The application of functional linkage from SACs and SSSIs, informed by the movements evidenced in this research, could aid management efforts. This analysis reveals grey seal movements occur across a complex network of interconnected designated and non-designated sites that need to be managed holistically for this species for which the UK has a special responsibility
Nonperturbative corrections to the quark self-energy
Nonperturbative self-energy of a bound quark is computed gauge-invariantly in
the framework of background perturbation theory. The resulting Delta m^2_q is
negative and is a universal function of string tension and current quark mass.
The shift of hadron mass squared, M^2, due to Delta m^2_q is negative, large
for light quarks, and solves the long-standing problem of Regge intercepts in
relativistic quark models.Comment: LaTeX2e, 13 pages, minor differences are don
High rates of growth recorded for hawksbill sea turtles in Anegada, British Virgin Islands.
Management of species of conservation concern requires knowledge of demographic parameters, such as rates of recruitment, survival, and growth. In the Caribbean, hawksbill turtles (Eretmochelys imbricata) have been historically exploited in huge numbers to satisfy trade in their shells and meat. In the present study, we estimated growth rate of juvenile hawksbill turtles around Anegada, British Virgin Islands, using capture-mark-recapture of 59 turtles over periods of up to 649 days. Turtles were recaptured up to six times, having moved up to 5.9 km from the release location. Across all sizes, turtles grew at an average rate of 9.3 cm year(-1) (range 2.3-20.3 cm year(-1)), and gained mass at an average of 3.9 kg year(-1) (range 850 g-16.1 kg year(-1)). Carapace length was a significant predictor of growth rate and mass gain, but there was no relationship between either variable and sea surface temperature. These are among the fastest rates of growth reported for this species, with seven turtles growing at a rate that would increase their body size by more than half per year (51-69% increase in body length). This study also demonstrates the importance of shallow water reef systems for the developmental habitat for juvenile hawksbill turtles. Although growth rates for posthatching turtles in the pelagic, and turtles larger than 61 cm, are not known for this population, the implications of this study are that Caribbean hawksbill turtles in some areas may reach body sizes suggesting sexual maturity in less time than previously considered.This work was part funded by the UK Darwin Initiative
(Project Ref. No. 162/12/023), NERC and the Japan Bekko
Association. LAH is supported by Streamlining of
Ocean Wavefarms Impact Assessment (SOWFIA) project
and MJW was in receipt of a Natural Environment
Research Council (NERC) PhD studentship (NER/S/A/
2004/12980) during the fieldwork. We thank the BVI
National Parks Trust for their support and assistance. All
work was sanctioned by the Conservation and Fisheries
Department of the British Virgin Islands Government
Self-reported body fat change in HIV-infected men is a marker of decline in physical health-related quality of life with aging, independent of co-morbidity
Objective: Self-perception of changes in body fat among HIV+ persons is associated with decreased health related quality of life in cross-sectional studies. The longitudinal impact of body fat changes on health related quality of life, while accounting for comorbidity and anatomic location or severity of body fat changes, is unknown. Design: This was a longitudinal analysis of HIV+ and HIV- Multicenter AIDS Cohort Study (MACS) participants who completed questionnaires assessing self-perceived body fat changes (baseline visit) and a health related quality of life (Short Form-36) at baseline and then ≥5 years later. Methods: Relationships between body fat changes and change in Short Form-36 Physical and Mental Component Summary scores were investigated using mixedmodel regression. Results: We studied 270 HIV+ and 247 HIV- men. At baseline, ≥50% of HIV+ men reported body fat changes; physical component but not mental component summary scores were lower among HIV+ men who reported moderate/severe leg or abdominal fat changes (p<0.05). At follow-up, physical component summary scores were significantly lower among men with face, leg, or abdominal fat changes compared to men without perceived fat changes (p<0.05). No significant changes were seen in mental component scores by fat change location or severity. In the final model, body fat changes at any site or severity were significant predictors of a decline in physical component summary score (p<0.05), independent of demographics or comorbidities. Mental component summary score was not associated with body fat changes, but higher mental component summary score was associated with increasing age and time. Conclusions: Negative self-perceived body fat changes were associated with decline in physical health related quality of life, independent of comorbidities, and may be a marker of an increased risk for physical function decline with aging
Polarimetry of Li-rich giants
Protoplanetary nebulae typically present non-spherical envelopes. The origin
of such geometry is still controversial. There are indications that it may be
carried over from an earlier phase of stellar evolution, such as the AGB phase.
But how early in the star's evolution does the non-spherical envelope appear?
Li-rich giants show dusty circumstellar envelopes that can help answer that
question. We study a sample of fourteen Li-rich giants using optical
polarimetry in order to detect non-spherical envelopes around them. We used the
IAGPOL imaging polarimeter to obtain optical linear polarization measurements
in V band. Foreground polarization was estimated using the field stars in each
CCD frame. After foreground polarization was removed, seven objects presented
low intrinsic polarization (0.19 - 0.34)% and two (V859 Aql and GCSS 557)
showed high intrinsic polarization values (0.87 - 1.16)%. This intrinsic
polarization suggests that Li-rich giants present a non-spherical distribution
of circumstellar dust. The intrinsic polarization level is probably related to
the viewing angle of the envelope, with higher levels indicating objects viewed
closer to edge-on. The correlation of the observed polarization with optical
color excess gives additional support to the circumstellar origin of the
intrinsic polarization in Li-rich giants. The intrinsic polarization correlates
even better with the IRAS 25 microns far infrared emission. Analysis of
spectral energy distributions for the sample show dust temperatures for the
envelopes tend to be between 190 and 260 K. We suggest that dust scattering is
indeed responsible for the optical intrinsic polarization in Li-rich giants.
Our findings indicate that non-spherical envelopes may appear as early as the
red giant phase of stellar evolution.Comment: to be published in A&A, 15 pages, 10 figures. Fig. 3 is available in
ftp://astroweb.iag.usp.br/pub/antonio/4270/4270.fig3.pd
Supersymmetry versus Integrability in two-dimensional Classical Mechanics
Supersymmetric extensions of Hamilton-Jacobi separable Liouville mechanical
systems with two degrees of freedom are defined. It is shown that supersymmetry
can be implemented in this type of systems in two independent ways. The
structure of the constants of motion is unveiled and the entanglement between
integrability and supersymmetry is explored.Comment: 28 pages, Added reference
Seasonal changes in basking shark vertical space-use in the north-east Atlantic
This is the final version. Available on open access from Springer via the DOI in this recordMobile marine species can exhibit vast movements both horizontally and vertically. Spatial analysis of vertical movements may help improve an understanding of the processes that influence space-use. Previously, vertical space-use of basking sharks (Cetorhinus maximus) in the north-east Atlantic described movements largely within waters of the continental shelf during summer and autumn months, with few records of detailed vertical behaviour during winter. We use archival satellite telemetry data from 32 basking sharks (twelve females, six males, and fourteen of unknown sex measuring 4-5 m (n = 6), 5-6 m (n = 10), 6-7 m (n = 7), 7-8 m (n = 8), and 8-9 m (n = 1) estimated total length) tracked over four years (2012-2015). The satellite tags provided depth and temperature data for a cumulative 4,489 days (mean 140 ± 97 days per shark, range: 10-292 days) in order to describe vertical space-use and thermal range of basking sharks in the north-east Atlantic. Basking sharks exhibit seasonality in vertical space-use, revealing repeated ‘yo-yo’ movement behaviour with periods of occupancy at depths greater than 1,000 metres in late winter/early spring. Describing seasonal vertical space-use in marine megavertebrates can increase knowledge of movements throughout their environment including physiological and morphological constraints to movement, nutrient transfer, and overlap with anthropogenic threats in order to inform future conservation strategies.Scottish Natural HeritageUniversity of ExeterNER
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