Applied and theoretical considerations for constructing spatially explicit individual-based models of marine larval fish that include multiple trophic levels   总被引：3，自引：2，他引：3  

Hermann  Albert J.; Hinckley  Sarah; Megrey  Bernard A.; Napp  Jeffrey M. 《ICES Journal of Marine Science》2001,58(5):1030-1041

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Managing South Africa's trawl bycatch     

Walmsley  Sarah A.; Leslie  Rob W.; Sauer  Warwick H. H. 《ICES Journal of Marine Science》2007,64(2):405-412

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Subsistence in coastal fisheries policy: What's in a word?   总被引：1，自引：2，他引：1  

Sarah Schumann  Seth Macinko   《Marine Policy》2007,31(6):706-718

Consideration of subsistence fishing activities seems particularly relevant to coastal fisheries policy, yet formal recognition of subsistence fishing is often absent from associated policy frameworks. A critical problem is the very meaning of the term “subsistence.” A review of the literature on subsistence, dominated until recently by North American research, reveals a schism between interpretations emphasizing material aspects of subsistence and interpretations highlighting cultural aspects. The North American literature on the subject is heavily influenced by a focus on Arctic indigenous populations emphasizing cultural survival. Ultimately, subsistence can be a matter of survival in the belly, the soul, or both. International case studies suggest that different interpretations of subsistence are appropriate in different circumstances, and that appropriate policy can be fashioned only after the local context of subsistence is understood.  相似文献   

Plio-Pleistocene microtephra in DSDP site 231, Gulf of Aden   总被引：1，自引：0，他引：1  

Sarah J. Feakins  Francis H. Brown  Peter B. deMenocal 《Journal of African Earth Sciences》2007,48(5):341-352

We reconstruct a Plio-Pleistocene microscopic tephrostratigraphy for DSDP Site 231 in the Gulf of Aden. Systematic microtephrostratigraphy increases the potential for identifying tephra horizons for regional stratigraphic correlation and age control, as well as providing information about eruptive histories. Microtephra reveal three main pulses of volcanism c. 4.0–3.2 Ma, 2.4 Ma and 1.7–1.3 Ma, corresponding to peaks in volcanic activity recorded in the East African Rift System. Previous studies of DSDP Site 231 have reported six visible tephra horizons (up to 25 cm thick) with geochemical compositions matching East African tuffs. We find 68 additional microtephra horizons through microscopic examination of 1050 samples (each integrating c. 3 ka) in over 200 m of marine sediments. We report the major and minor element geochemical compositions of individual glass shards in six of these microtephra horizons and establish a robust correlation at 168.73 m to the Lokochot Tuff (3.58 Ma), which together with previously identified tephra, provides a tightly constrained chronostratigraphy for the mid Pliocene.  相似文献   

Remote sensing for groundwater modelling in large semiarid areas: Lake Chad Basin,Africa     

Marc Leblanc  Guillaume Favreau  Sarah Tweed  Christian Leduc  Moumtaz Razack  Linus Mofor 《Hydrogeology Journal》2007,15(1):97-100

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Sulfur and carbon isotope geochemistry of coal and derived coal-combustion by-products: An example from an Eastern Kentucky mine and power plant     

Erika R. Elswick  James C. Hower  Ana M. Carmo  Tao Sun  Sarah M. Mardon 《Applied Geochemistry》2007

The isotopic compositions of S (δ³⁴S) and C (δ¹³C) were determined for the coal utilized by a power plant and for the fly ash produced as a by-product of the coal combustion in a 220-MW utility boiler. The coal samples analyzed represent different lithologies within a single mine, the coal supplied to the power plant, the pulverized feed coal, and the coal rejected by the pulverizer. The ash was collected at various stages of the ash-collection system in the plant. There is a notable enrichment in ³⁴S from the base to the top of the coal seam in the mine, with much of the variation due to an upwards enrichment in the δ³⁴S values of the pyrite. Variations in δ³⁴S and in the amount of pyritic S in the coal delivered to the plant show that there was a change of source of coal supplied to the plant, between week one and week two of monitoring, supporting a previous study based on metal and sulfide geochemistry for the same plant. The fly ash has a more enriched δ³⁴S than the pulverized coal and, in general, the δ³⁴S is more enriched in fly ashes collected at cooler points in the ash-collection system. This pattern of δ³⁴S suggests an increased isotopic fractionation due to temperature, with the fly ash becoming progressively depleted in ³⁴S and the flue gas S-containing components becoming progressively enriched in ³⁴S with increasing temperatures. Substantially less variation is seen in the C isotopes compared to S isotopes. There is little vertical variation in δ¹³C in the coal bed, with δ¹³C becoming slightly heavier towards the top of the coal seam. An 83–93% loss of solid phase C occurs during coal combustion in the transition from coal to ash owing to loss of CO₂. Despite the significant difference in total C content only a small enrichment of 0.44–0.67‰ in ¹³C in the ash relative to the coal is observed, demonstrating that redistribution of C isotopes in the boiler and convective passes prior to the arrival of the fly ash in the ash-collections system is minor.  相似文献   

‘You can get away with loads because there’s no one here’: Discourses of regulation and non-regulation in English rural spaces     

Sarah Neal  Sue Walters 《Geoforum》2007,38(2):252-263

Using qualitative data from a research project investigating contemporary rural identities in England this paper examines the apparently contradictory discursive claims that are made on rural spaces. It looks in particular at the ways in which these are narrated - through the notions of rural space as a site of safety, orderliness and community on the one hand and as a site of freedom, anti-order and non-regulation on the other. While the former is a familiar, entrenched and critiqued representation of rurality, the latter narrative has a more marginal and ambivalent place in the dominant rural imaginary. Drawing on Foucault’s concepts of panopticism and heterotopia the paper demonstrates the ways in which the rural is a highly labile concept and emphasises its continual ‘unfinishedness’. However, alongside this, the paper suggests that the tensions and contradictions of the orderly and anti-orderly discourses are underpinned by a particular coherency that is driven by senses of community, belonging and self-regulation. While these do not resolve the contradictions of the discursive claims the potency of such drivers are sufficient to produce a particular inclusive spatiality which is able to accommodate and incorporate the different discursive positions and the practices that are associated with each.  相似文献   

CARBON AND NITROGEN STORAGE IN SOIL AND LITTER OF SOUTHERN CALIFORNIAN SEMI-ARID SHRUBLANDS     

Vourlitis GL  Zorba G  Pasquini SC  Mustard R 《Journal of Arid Environments》2007,70(1):164-173

Semi-arid shrublands of southern California, including chaparral and coastal sage, are found in widely varying elevation and microclimatic regimes and are subjected to disturbance such as fire and atmospheric N deposition that have the capacity to alter soil and litter C and N storage. Here we present a case study where soil and litter C and N were measured over 19 months in post-fire chaparral and mature coastal sage stands to assess whether differences in soil and litter C and N between these diverse shrublands could be attributed to differences in elevation, stand age, rainfall, and/or estimated N deposition exposure. Our results indicate that atmospheric N deposition exposure, either alone or in conjunction with other environmental variables (elevation, rainfall, and/or stand age), was the most frequent predictor of the spatial pattern in the soil and litter N and C variables observed. These results are consistent with those reported for high-elevation coniferous forests arrayed along an N deposition gradient in southern California, suggesting that N deposition may affect the soil N and C storage of semiarid shrublands and woodlands in a qualitatively similar manner.  相似文献   

Geographies of care: A commentary     

Christine Milligan  Sarah Atkinson  Mark Skinner  Janine Wiles 《New Zealand geographer》2007,63(2):135-140

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Online GPS processing services: an initial study   总被引：1，自引：2，他引：1  

Reza Ghoddousi-Fard  Peter Dare 《GPS Solutions》2006,10(1):12-20

There are a number of online Global Positioning System (GPS) processing services that provide GPS processing results to the user free of charge and with unlimited access. These services provide solutions for a user-submitted Receiver Independent Exchange Format (RINEX) file based on differential methods using reference stations or precise point positioning using precise GPS orbit and clock data. Different data sets varying in time and location were submitted to the online services and their results compared. Although the quality of results depends on many factors, in most cases the users can expect reliable online processing results for a 10-h data set made by a geodetic dual frequency receiver anywhere in the world.  相似文献