XVIIth INTERNATIONAL CONGRESS OF PHOTOGRAMMETRY AND REMOTE SENSING     

K. B. Atkinson  I. J. Dowman  J. E. Farrow  P. R. T. Newby  I. Newton  M. J. Smith  D. M. Stirling 《The Photogrammetric Record》1993,14(81):477-503

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Magnetospheric birefringence induces polarization signatures in neutron-star spectra     

R. M. Shannon †  J. S. Heyl †‡ 《Monthly notices of the Royal Astronomical Society》2006,368(3):1377-1380

We study the propagation of polarization light through the magnetosphere of neutron stars. At intermediate frequencies (the optical through the infrared), the birefringence induced both by the plasma and by quantum electrodynamics influences the observed polarization of radiation from the surface of the neutron star. Because these two processes compete in this regime, we find that polarization observations can constrain the properties of the neutron-star magnetosphere, specifically the total charge density. We calculate both the phase-resolved and the phase-averaged polarization signatures induced by magnetospheric birefringence.  相似文献   

Book Review     

Shannon O’Lear 《GeoJournal》2005,64(4):333-337

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UBRI photometry of globular clusters in the Leo group galaxy NGC 3379     

Shannon Whitlock  Duncan A. Forbes  Michael A. Beasley 《Monthly notices of the Royal Astronomical Society》2003,345(3):949-959

We present wide-area UBRI photometry for globular clusters around the Leo group galaxy NGC 3379. Globular cluster candidates are selected from their B -band magnitudes and their  ( U − B ) _o   versus  ( B − I ) _o   colours. A colour–colour selection region was defined from photometry of the Milky Way and M31 globular cluster systems. We detect 133 globular cluster candidates, which supports previous claims of a low specific frequency for NGC 3379.
The Milky Way and M31 reveal blue and red subpopulations, with  ( U − B ) _o   and  ( B − I ) _o   colours indicating mean metallicities similar to those expected based on previous spectroscopic work. The stellar population models of Maraston and Brocato et al. are consistent with both subpopulations being old, and with metallicities of  [Fe/H]∼−1.5  and −0.6 for the blue and red subpopulations, respectively. The models of Worthey do not reproduce the  ( U − B ) _o   colours of the red (metal-rich) subpopulation for any modelled age.
For NGC 3379 we detect a blue subpopulation with similar colours, and presumably age/metallicity, to that of the Milky Way and M31 globular cluster systems. The red subpopulation is less well defined, perhaps due to increased photometric errors, but indicates a mean metallicity of [Fe/H]∼−0.6.  相似文献   

Correspondence     

K. B. Atkinson 《The Photogrammetric Record》2006,21(115):296-297

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Spatial Distribution-Abundance Relationships in Juvenile (Age-0) Red Drum (<Emphasis Type="Italic">Sciaenops Ocellatus</Emphasis>) and Spotted Seatrout (<Emphasis Type="Italic">Cynoscion Nebulosus</Emphasis>). II: Influence of Major Disturbances     

Shannon D. Whaley  Mary C. Christman  James J. BurdJr. 《Estuaries and Coasts》2016,39(3):752-758

Local species populations that are more numerically abundant and occupy a greater proportion of the landscape relative to other species often recover more quickly (i.e., are more resilient) following local-scale environmental perturbations. In a companion study, we found that seatrout juvenile populations were distributed more broadly across Tampa Bay, Florida, and numerical abundance was generally much higher than those of similar-sized red drum, suggesting that spotted seatrout may also be generally more resilient to population declines than red drum. Following major population declines over a 12-year period (1996–2008), we found that larger juveniles of seatrout (51–100 mm standard length) simultaneously gained numerical abundance and broadened their spatial distribution generally within the next year. Population recovery in the same size of juvenile red drum generally took multiple years, and distribution and abundance increases were not always concurrent during the recovery period. Despite their overall higher abundance and broader spatial distribution, the smaller-sized juveniles of spotted seatrout (15–50 mm standard length (SL)) did not always recover more quickly from population declines compared with similar-sized red drum. Populations of the smaller-sized juveniles of both species often took multiple years to recover and showed non-concurrent increases in distribution and abundance during recovery. Despite their relatively narrow spatial distribution, juveniles of red drum may increase their overall resilience to local environmental perturbations by occupying multiple isolated patches across the Tampa Bay landscape. Monitoring dynamics of numerical abundance and spatial distribution may be helpful in gauging relative population resilience to facilitate overall management of these fishery populations.  相似文献   

Ecosystem modelling in the southern Benguela: comparisons of Atlantis,Ecopath with Ecosim,and OSMOSE under fishing scenarios     

MD Smith  EA Fulton  RW Day  LJ Shannon  Y-J Shin 《African Journal of Marine Science》2015,37(1):65-78

Ecosystem-based management of marine fisheries requires the use of simulation modelling to investigate the system-level impact of candidate fisheries management strategies. However, testing of fundamental assumptions such as system structure or process formulations is rarely done. In this study, we compare the output of three different ecosystem models (Atlantis, Ecopath with Ecosim, and OSMOSE) applied to the same ecosystem (the southern Benguela), to explore which ecosystem effects of fishing are most sensitive to model uncertainty. We subjected the models to two contrasting fishing pressure scenarios, applying high fishing pressure to either small pelagic fish or to adult hake. We compared the resulting model behaviour at a system level, and also at the level of model groups. We analysed the outputs in terms of various commonly used ecosystem indicators, and found some similarities in the overall behaviour of the models, despite major differences in model formulation and assumptions. Direction of change in system-level indicators was consistent for all models under the hake pressure scenario, although discrepancies emerged under the small-pelagic-fish scenario. Studying biomass response of individual model groups was key to understanding more integrated system-level metrics. All three models are based on existing knowledge of the system, and the convergence of model results increases confidence in the robustness of the model outputs. Points of divergence in the model results suggest important areas of future study. The use of feeding guilds to provide indicators for fish species at an aggregated level was explored, and proved to be an interesting alternative to aggregation by trophic level.  相似文献   

A systematic review of landslide probability mapping using logistic regression   总被引：2，自引：0，他引：2  

M. E. A. Budimir  P. M. Atkinson  H. G. Lewis 《Landslides》2015,12(3):419-436

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On the coattails of climate? Opportunities and threats of a warming Earth for biodiversity conservation     

Shannon Hagerman  Rebecca Witter  Catherine Corson  Daniel Suarez  Edward M. Maclin  Maggie Bourque  Lisa Campbell 《Global Environmental Change》2012,22(3):724-735

The relationship between climate change and biodiversity was a central issue at the 10th Conference of the Parties (COP 10) to the Convention on Biological Diversity (CBD). In this paper we draw from participant observation data collected at COP 10, and related policy documentation, to examine how concerns about climate change are shaping the conservation policy landscape – in terms of the knowledge and rationales used as inputs, networks of actors involved, objectives sought, and actions proposed. We find that debates at the intersection of climate and biodiversity were overwhelmingly framed in relation to, or through the lens of carbon. Through a discussion of four core Climate-Motivated Responses, we illustrate how “carbon-logic”, and the initiatives that it generates, simultaneously creates threats to the objectives sought by some actors, and opportunities for the objectives sought by others. We situate our observations in the context of some of the historical dilemmas that have faced conservation, and discuss this current moment in the dynamic trajectory of conservation governance: a moment when decisions about conserving biodiversity are becoming entangled with carbon-logic and the market. In this case, while some actors seek opportunities for biodiversity ends by riding the coattails of the climate agenda, the threats of doing so may undermine the biological and social objectives of the CBD convention itself.  相似文献   

On the use of the stress relaxation testing method in studies of the mechanical behaviour of geological materials     

E. H. Rutter  B. K. Atkinson  D. H. Mainprice 《Geophysical Journal International》1978,55(1):155-170

Summary. A summary is presented of the use of stress relaxation testing in studies of the mechanical behaviour of materials with emphasis on the underlying assumptions of the method. It is shown that relaxation testing is a powerful experimental method which could profitably be used in future studies of the mechanical properties of geological materials to augment, but not to replace, the more conventional creep and constant strain rate tests.
Stress relaxation data can be analysed to determine important parameters in equations describing (a) laws of flow and fracture, and (b) dislocation dynamics. The variation of the first derivative of any stress relaxation curve with stress can be used to establish the applied stress sensitivity to strain rate and the values of activation parameters such as 'activation volume'. Such parameters may be used to constrain the inference of the dominant deformation mechanism. This account is illustrated by reference to some recent experiments on polycrystalline, synthetic galena (lead sulphide) and pre-faulted cylinders of Tennessee sandstone deformed over a wide range of environmental conditions. The accurate sensing of the second derivative of a relaxation curve is required to establish parameters relating to dislocation dynamics, e.g. partition between thermal and athermal components of applied stress, and the stress dependence of dislocation velocity. The determination of such parameters is illustrated with new experiments on single crystals of calcite.  相似文献