Gill net selectivity and catch rates of coastal pelagic fish in Jamaica     

C.J. Grant 《Estuarine, Coastal and Shelf Science》1981,12(2):167-175

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DYNAMICS IN THE STRUCTURAL FORM OF PROPERTY TAXES*     

Grant Ian Thrall 《The Professional geographer》1981,33(4):450-456

Because the property tax is structurally tied to market values of dwellings through the assessment function, rapidly increasing market values may beget rapid increases in property taxes. Public awareness of this process was instrumental in California's 1978 passage of the Jarvis-Gann Amendment. Millage rates should be indexed to counterbalance changes in market values.  相似文献   

A network-based telemetry architecture developed for the Martha'sVineyard Coastal Observatory     

Austin  T.C. Edson  J.B. McGillis  W.R. Purcell  M. Petitt  R.A.  Jr. McElroy  M.K. Grant  C.W. Ware  J. Hurst  S.K. 《Oceanic Engineering, IEEE Journal of》2002,27(2):228-234

Underwater observatories with real-time data and virtually unlimited power transmission capabilities compared to traditional oceanographic moorings are beginning to provide scientists with continuous access to the coastal and open ocean. However, for any coastal observatory to serve as a cost-effective system for the collection of long-term scientific and environmental data, it must have a simple, upgradeable power and telemetry system and an instrument interface that is compatible with existing standards. It must be designed for extended environmental exposure and ease of service to avoid high maintenance costs. Most importantly, the observatory must be accessible to all potential users, including students, scientists, engineers, and policy makers. This strategy was applied to the design of the Martha's Vineyard Coastal Observatory on the south shore of the island of Martha's Vineyard. The new facility, and in particular its system architecture, as developed by the Woods Hole Oceanographic Institution with support from the National Science Foundation, are described  相似文献   

A GEOGRAPHIC CRITERION FOR IDENTIFYING PROPERTY-TAX ASSESSMENT INEQUITY     

Grant lan Thrall 《The Professional geographer》1979,31(3):278-283

Equitable tax assessment requires that houses having the same market value must also have identical assessed values. With a map of dwellings' assessed-value-to-market-value ratios, it is possible to identify neighborhoods that are significantly overassessed or underassessed; this can lead to an understanding of the causes of misassessment. When houses or neighborhoods are demonstrated to be inequitably assessed, corrective action can be taken to eliminate the inequity. This essay is an example of the application of geographic techniques to spatial public-policy formulation.  相似文献   

Nutrient transfer from soil to surface waters: Differences between nitrate and phosphate   总被引：3，自引：0，他引：3  

René?G?chterEmail author  Sandra?M.?Steingruber  Miriam?Reinhardt  Bernhard?Wehrli 《Aquatic Sciences - Research Across Boundaries》2004,66(1):117-122

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Reconstruction of past methane availability in an Arctic Alaska wetland indicates climate influenced methane release during the past ~12,000?years     

Matthew J. Wooller  John W. Pohlman  Benjamin V. Gaglioti  Peter Langdon  Miriam Jones  Katey M. Walter Anthony  Kevin W. Becker  Kai-Uwe Hinrichs  Marcus Elvert 《Journal of Paleolimnology》2012,48(1):27-42

Atmospheric contributions of methane from Arctic wetlands during the Holocene are dynamic and linked to climate oscillations. However, long-term records linking climate variability to methane availability in Arctic wetlands are lacking. We present a multi-proxy ~12,000?year paleoecological reconstruction of intermittent methane availability from a radiocarbon-dated sediment core (LQ-West) taken from a shallow tundra lake (Qalluuraq Lake) in Arctic Alaska. Specifically, stable carbon isotopic values of photosynthetic biomarkers and methane are utilized to estimate the proportional contribution of methane-derived carbon to lake-sediment-preserved benthic (chironomids) and pelagic (cladocerans) components over the last ~12,000?years. These results were compared to temperature, hydrologic, and habitat reconstructions from the same site using chironomid assemblage data, oxygen isotopes of chironomid head capsules, and radiocarbon ages of plant macrofossils. Cladoceran ephippia from ~4,000?cal?year BP sediments have ??¹³C values that range from ~?39 to ?31??, suggesting peak methane carbon assimilation at that time. These low ??¹³C values coincide with an apparent decrease in effective moisture and development of a wetland that included Sphagnum subsecundum. Incorporation of methane-derived carbon by chironomids and cladocerans decreased from ~2,500 to 1,500?cal?year BP, coinciding with a temperature decrease. Live-collected chironomids with a radiocarbon age of 1,640?cal?year BP, and fossil chironomids from 1,500?cal?year BP in the core illustrate that ??old?? carbon has also contributed to the development of the aquatic ecosystem since ~1,500?cal?year BP. The relatively low ??¹³C values of aquatic invertebrates (as low as ?40.5??) provide evidence of methane incorporation by lake invertebrates, and suggest intermittent climate-linked methane release from the lake throughout the Holocene.  相似文献   

Effects of observed and experimental climate change on terrestrial ecosystems in northern Canada: results from the Canadian IPY program   总被引：1，自引：0，他引：1  

Gregory H. R. Henry  Karen A. Harper  Wenjun Chen  Julie R. Deslippe  Robert F. Grant  Peter M. Lafleur  Esther Lévesque  Steven D. Siciliano  Suzanne W. Simard 《Climatic change》2012,115(1):207-234

Tundra and taiga ecosystems comprise nearly 40?% of the terrestrial landscapes of Canada. These permafrost ecosystems have supported humans for more than 4500?years, and are currently home to ca. 115,000 people, the majority of whom are First Nations, Inuit and Métis. The responses of these ecosystems to the regional warming over the past 30?C50?years were the focus of four Canadian IPY projects. Northern residents and researchers reported changes in climate and weather patterns and noted shifts in vegetation and other environmental variables. In forest-tundra areas tree growth and reproductive effort correlated with temperature, but seedling establishment was often hindered by other factors resulting in site-specific responses. Increased shrub cover has occurred in sites across the Arctic at the plot and landscape scale, and this was supported by results from experimental warming. Experimental warming increased vegetation cover and nutrient availability in most tundra soils; however, resistance to warming was also found. Soil microbial diversity in tundra was no different than in other biomes, although there were shifts in mycorrhizal diversity in warming experiments. All sites measured were sinks for carbon during the growing season, with expected seasonal and latitudinal patterns. Modeled responses of a mesic tundra system to climate change showed that the sink status will likely continue for the next 50?C100?years, after which these tundra systems will likely become a net source of carbon dioxide to the atmosphere. These IPY studies were the first comprehensive assessment of the state and change in Canadian northern terrestrial ecosystems and showed that the inherent variability in these systems is reflected in their site-specific responses to changes in climate. They also showed the importance of using local traditional knowledge and science, and provided extensive data sets, sites and researchers needed to study and manage the inevitable changes in the Canadian North.  相似文献   

Potential impact of climate change on carbon in agricultural soils in Canada 2000–2099     

W. N. Smith  B. B. Grant  R. L. Desjardins  B. Qian  J. Hutchinson  S. Gameda 《Climatic change》2009,93(3-4):319-333

Under the threat of global warming it is important to determine the impact that future changes in climate may have on the environment and to what extent any adverse effects can be mitigated. In this study we assessed the impact that climate change scenarios may have on soil carbon stocks in Canada and examined the potential for agricultural management practices to improve or maintain soil quality. Historical weather data from 1951 to 2001 indicated that semi-arid soils in western Canada have become warmer and dryer and air temperatures have increased during the spring and winter months. Results from the Canadian Center for Climate Modelling and Analysis (CCCma) Coupled Global Climate Model (CGCM1,2) under two climate change forcing scenarios also indicated that future temperatures would increase more in the spring and winter. Precipitation increased significantly under the IPCC IS92a scenario and agreed with historical trends in eastern Canada whereas the IPCC SRES B2 scenario indicated very little change in precipitation and better matched historical trends in western Canada. The Century model was used to examine the influence of climate change on agricultural soil carbon (C) stocks in Canada. Relative to simulations using historical weather data, model results under the SRES B2 climate scenario indicated that agricultural soils would lose 160 Tg of carbon by 2099 and under the IS92a scenario would lose 53 Tg C. Carbon was still lost from soils in humid climatic regions even though C inputs from crops increased by 10–13%. Carbon factors associated with changes in management practices were also estimated under both climate change scenarios. There was little difference in factors associated with conversion from conventional to no-till agriculture, while carbon factors associated with the conversion of annual crops to perennial grass were lower than for historical data in semi-arid soils because water stress hampered crop production but were higher in humid soils.  相似文献   

TNOs are Cool: A Survey of the Transneptunian Region     

Thomas G. Müller  Emmanuel Lellouch  Hermann Böhnhardt  John Stansberry  Antonella Barucci  Jacques Crovisier  Audrey Delsanti  Alain Doressoundiram  Elisabetta Dotto  René Duffard  Sonia Fornasier  Olivier Groussin  Pedro J. Gutiérrez  Olivier Hainaut  Alan W. Harris  Paul Hartogh  Daniel Hestroffer  Jonathan Horner  Dave Jewitt  Mark Kidger  Csaba Kiss  Pedro Lacerda  Luisa Lara  Tanya Lim  Michael Mueller  Raphael Moreno  Jose-Luis Ortiz  Miriam Rengel  Pablo Santos-Sanz  Bruce Swinyard  Nicolas Thomas  Audrey Thirouin  David Trilling 《Earth, Moon, and Planets》2009,105(2-4):209-219

Over one thousand objects have so far been discovered orbiting beyond Neptune. These trans-Neptunian objects (TNOs) represent the primitive remnants of the planetesimal disk from which the planets formed and are perhaps analogous to the unseen dust parent-bodies in debris disks observed around other main-sequence stars. The dynamical and physical properties of these bodies provide unique and important constraints on formation and evolution models of the Solar System. While the dynamical architecture in this region (also known as the Kuiper Belt) is becoming relatively clear, the physical properties of the objects are still largely unexplored. In particular, fundamental parameters such as size, albedo, density and thermal properties are difficult to measure. Measurements of thermal emission, which peaks at far-IR wavelengths, offer the best means available to determine the physical properties. While Spitzer has provided some results, notably revealing a large albedo diversity in this population, the increased sensitivity of Herschel and its superior wavelength coverage should permit profound advances in the field. Within our accepted project we propose to perform radiometric measurements of 139 objects, including 25 known multiple systems. When combined with measurements of the dust population beyond Neptune (e.g. from the New Horizons mission to Pluto), our results will provide a benchmark for understanding the Solar debris disk, and extra-solar ones as well.  相似文献   

Scanning electron microscopical and cross sectional analysis of extraterrestrial carbonaceous nanoglobules     

Laurence A. J. GARVIE  Grant BAUMGARDNER  Peter R. BUSECK 《Meteoritics & planetary science》2008,43(5):899-903

Abstract— Carbonaceous nanoglobules are ubiquitous in carbonaceous chondrite (CC) meteorites. The Tagish Lake (C2) meteorite is particularly intriguing in containing an abundance of nanoglobules, with a wider range of forms and sizes than encountered in other CC meteorites. Previous studies by transmission electron microscopy (TEM) have provided a wealth of information on chemistry and structure. In this study low voltage scanning electron microscopy (SEM) was used to characterize the globule forms and external structures. The internal structure of the globules was investigated after sectioning by focused ion beam (FIB) milling. The FIB‐SEM analysis shows that the globules range from solid to hollow. Some hollow globules show a central open core, with adjoining smaller cores. The FIB with an SEM is a valuable tool for the analysis of extraterrestrial materials, even of sub‐micron‐sized “soft” carbonaceous particles. The rapid site‐specific cross‐sectioning capabilities of the FIB allow the preservation of the internal morphology of the nanoglobules, with minimal damage or alteration of the unsectioned areas.  相似文献