Emerging and vector-borne diseases: Role of high spatial resolution and hyperspectral images in analyses and forecasts     

Mark L. Wilson 《Journal of Geographical Systems》2002,4(1):31-42

 Many infectious diseases that are emerging or transmitted by arthropod vectors have a strong link to landscape features. Depending on the source of infection or ecology of the transmitting vector, micro-habitat characteristics at the spatial scale of square meters or less may be important. Recently, satellite images have been used to classify habitats in an attempt to understand associations with infectious diseases. Whether high spatial resolution and hyperspectral (HSRH) images can be useful in studies of such infectious diseases is addressed. The nature of questions that such studies address and the desired accuracy and precision of answers will determine the utility of HSRH data. Need for such data should be based on the goals of the effort. Examples of kinds of questions and applications are discussed. The research implications and public health applications may depend on available analytic tools as well as epidemiological observations. Received: 30 July 2001 / Accepted: 14 October 2001  相似文献   

Interactive Analysis Using Voronoi Diagrams: Algorithms to Support Dynamic Update from a Generic Triangle-based Data Structure     

Ickjai Lee  & Mark Gahegan 《Transactions in GIS》2002,6(2):89-114

This paper describes a series of dynamic update methods that can be applied to a family of Voronoi diagram types, so that changes can be updated incrementally, without the usual recourse to complete reconstruction of their underlying data structure. More efficient incremental update methods are described for the ordinary Voronoi diagram, the farthest-point Voronoi diagram, the order- k Voronoi diagram and the ordered order- k Voronoi diagram. A discussion is also given of one case where incremental update is not practical, that of the multiplicatively weighted Voronoi diagram. Update methods rely on a previously reported generic, triangle-based data structure (Gahegan and Lee 2000) from which local topology can be dynamically reconstructed following changes to the underlying pointset. An application, which implements these ideas, is available for download via the Internet as proof of concept. Results show that the algorithmic complexity of dynamic update methods vary considerably according to the Voronoi type, but offer in all cases (except the multiplicatively weighted Voronoi diagram) a substantial increase in performance, enabling Voronoi methods to address larger pointsets and more complex modelling problems without incurring too great a computational burden.  相似文献   

Datation UPb sur zircons des dolérites tholéiitiques pyrénéennes (ophites) à la limite Trias–Jurassique et relations avec les tufs volcaniques dits « infra-liasiques » nord-pyrénéens     

Philippe Rossi  Alain Cocherie  C.Mark Fanning  Yves Ternet 《Comptes Rendus Geoscience》2003,335(15):1071-1080

The tholeiitic doleritic magmatism (ophites) in the Aspe valley of the Pyrenees has been dated on the Triassic–Jurassic boundary (199±2 Ma) by the UPb method on zircon (SHRIMP). Emplacement of the ophites was probably synchronous with that of the earliest ‘Infraliassic’ Ségalas tuffs. The ophites are thus related to the Central Atlantic Magmatic Province (CAMP) whose emplacement linked with the fracturing of Pangea, preceded the opening of the Atlantic Ocean. To cite this article: P. Rossi et al., C. R. Geoscience 335 (2003).  相似文献   

Reflections on current developments in contemporary urban geography     

Susan Moore  James Faulconbridge  Clare Blake  David Westhead  Tom Slater  Gavin Brown  Mark Davidson  Margo Huxley  Eddie Huijbens 《Area》2003,35(2):217-219

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Dispelling a myth? Second homes in rural Wales   总被引：1，自引：0，他引：1  

Nick Gallent  Alan Mace  Mark Tewdwr-Jones 《Area》2003,35(3):271-284

Second homes have been a source of considerable controversy in Wales for more than three decades. In this article we argue that they have, in reality, become less important in recent times, with the market contracting during the 1990s and other more fundamental demographic changes and housing pressures coming to the fore. Second homes are a highly localized issue, affecting a minority of communities – though, at times, quite severely. Retirement and other housing pressures, however, bring more significant socio-economic changes and these pressures are all too frequently amplified by a planning system used to restrict housing supply rather than manage growth. This paper has three parts, beginning with a general review of the second home debate followed by an examination of the changing geography of second homes, showing how the distribution of these properties altered during the 1990s and how the market contracted. It ends with a review of secondary data, revealing that second homes are a relatively small component of wider processes affecting rural communities, though extremely significant in some areas.  相似文献   

The CERES‐Rice Model‐Based Estimates of Potential Monsoon Season Rainfed Rice Productivity in Bangladesh*     

Rezaul Mahmood  Mark Meo  David R. Legates  Mark L. Morrissey 《The Professional geographer》2003,55(2):259-273

Agricultural practices in Bangladesh are largely dependent on the monsoonal rainfall. Historically, Bangladesh often experiences severe droughts and floods during the monsoon months, with significant crop losses during both extreme conditions. This article provides a quantitative assessment of potential monsoon‐season aman rice for four transplanting dates: 1 June, 1 July, 15 July, and 15 August. A crop‐growth simulation model, the CERES‐Rice, is applied to sixteen locations representing major rice‐growing regions of Bangladesh to determine baseline yield estimates for four transplanting dates. The applications were conducted for 1975 through 1987. Average potential yield in Bangladesh is 6,907, 5,039, 3,637, and 1,762 kg ha^?1 for the above transplanting dates, respectively. In other words, Bangladesh would obtain 27 percent, 48 percent, and 75 percent less yield for 1 July, 15 July, and 15 August transplanting, respectively, than for 1 June transplanting. Potential yield vulnerability is the least for 1 June transplanting (up to 5 percent) and the highest (up to 66 percent) for 15 July transplanting date. The model applications show that regional variations exist for potential yield and yield vulnerability for a particular transplanting date. In addition, response of yield and vulnerability for a region changes with transplanting dates.  相似文献   

Measurements Of Thermal Updraft Intensity Over Complex Terrain Using American White Pelicans And A Simple Boundary-Layer Forecast Model     

Harlan D. Shannon  George S. Young  Michael A. Yates  Mark R. Fuller  William S. Seegar 《Boundary-Layer Meteorology》2002,104(2):167-199

An examination of boundary-layer meteorological and avian aerodynamic theories suggests that soaring birds can be used to measure the magnitude of vertical air motions within the boundary layer. These theories are applied to obtain mixed-layer normalized thermal updraft intensity over both flat and complex terrain from the climb rates of soaring American white pelicans and from diagnostic boundary-layer model-produced estimates of the boundary-layer depth z_i and the convective velocity scale w_*. Comparison of the flatland data with the profiles of normalized updraft velocity obtained from previous studies reveals that the pelican-derived measurements of thermal updraft intensity are in close agreement with those obtained using traditional research aircraft and large eddy simulation (LES) in the height range of 0.2 to 0.8 z_i. Given the success of this method, the profiles of thermal vertical velocity over the flatland and the nearby mountains are compared. This comparison shows that these profiles are statistically indistinguishable over this height range, indicating that the profile for thermal updraft intensity varies little over this sample of complex terrain. These observations support the findings of a recent LES study that explored the turbulent structure of the boundary layer using a range of terrain specifications. For terrain similar in scale to that encountered in this study, results of the LES suggest that the terrain caused less than an 11% variation in the standard deviation of vertical velocity.  相似文献   

Emissions of Nitrous Oxide and Methane from Conventional and Alternative Fuel Motor Vehicles   总被引：1，自引：0，他引：1  

Timothy E. Lipman  Mark A. Delucchi 《Climatic change》2002,53(4):477-516

This paper provides estimates of emissions of two important but often not well-characterized greenhouse gas (GHG) emissions related to transportation energy use: methane (CH₄) and nitrous oxide (N₂O). The paper focuses on emissions of CH₄ and N₂O from motor vehicles because unlike emissions of CO₂, which are relatively easy to estimate, emissions of CH₄ and N₂O are a function of many complex aspects of combustion dynamics and of the type of emission control systems used. They therefore cannot be derived easily and instead must be determined through the use of published emission factors for each combination of fuel, end-use technology, combustion conditions, and emission control system. Furthermore, emissions of CH₄ and N₂O may be particularly important with regard to the relative CO₂-equivalent GHG emissions of the use of alternative transportation fuels, in comparison with the use of conventional fuels. By analyzing a database of emission estimates, we develop emission factors for N₂O and CH₄ from conventional vehicles, in order to supplement recent EPA and IPCC estimates, and we estimate relative emissions of N₂O and CH₄ from different alternative fuel passenger cars, light-duty trucks, and heavy-duty vehicles.  相似文献   

The role of basalt replenishment in the generation of basaltic andesites of the ongoing activity at Arenal volcano,Costa Rica: evidence from clinopyroxene and spinel   总被引：1，自引：0，他引：1  

Streck  Martin J.  Dungan  Michael A.  Malavassi  E.  Reagan  Mark K.  Bussy  Francois 《Bulletin of Volcanology》2002,64(5):316-327

Bulletin of Volcanology - The bulk composition of magma erupted from Volcán Arenal has remained nearly constant (SiO2 = 53.6–54.9&;nbsp;wt%; MgO = 5.0–4.5&;nbsp;wt%) during...  相似文献   

An algorithm to aid varve counting and measurement from thin-sections     

Pierre Francus  Frank Keimig  Mark Besonen 《Journal of Paleolimnology》2002,28(2):283-286

An algorithm has been implemented to count and measure laminations from digital images of petrographic thin-sections. Boundaries and limits of laminations are first marked manually using imaging software. These marks are then exported to a workable format output file. Using the output file, the algorithm extracts the relevant information for lamination counts and thickness measurements along one or more parallel vertical lines. Compared to manual counts, the use of the algorithm improves the accuracy of measurements and speeds up the process. The method requires tools commonly available in most laboratories, i.e., a digital camera or a flat bed scanner with transparency capability and a desktop computer with 64 MB of RAM. From the algorithm, two utilities are implemented in Visual Basic for Applications and Fortran to be used on both Apple Macintosh and a PC-compatible, with Adobe^® Photoshop^®.  相似文献