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91.
Online Survey of Heterogeneous Users and Their Usage of the Interactive Mapping Platform WorldMap 总被引:1,自引:0,他引:1
This article reports on the results of an online survey with 290 heterogeneous users of the interactive mapping platform WorldMap and provides insights into problems faced by such users. Heterogeneous users are users with a variety of GIS skills, educational background, gender, and age categories. We investigate how they interact with online maps and analyse their experience. WorldMap represents as a case study of an online mapping platform which aims to serve researchers and users across disciplines in viewing and creating online interactive maps. We concentrate on operations that are perceived as difficult and very difficult by the majority of users as well as operations that are rarely used. Our aim is to contribute to the discussions on how to improve the design of online GIS-based mapping platforms. We conclude the paper with reflections on the results of our study and ideas for further research. 相似文献
92.
John H. Trefry Bob J. Presley Wendy L. Keeney-Kennicutt Robert P. Trocine 《Geo-Marine Letters》1984,4(2):125-130
The intense halocline and redoxcline in the Orca Basin, northwest Gulf of Mexico, induce dramatic water column profiles for manganese, iron, and suspended particulates. Within a 17 m interval, the salinity of the basin water increases from 66 to 260 & permil and dissolved oxygen decreases to zero. Midway through this transition zone, concentrations of suspended matter peak at 900 g/liter. Dissolved iron and manganese concentrations in the anoxic brine increase from oceanic values to maxima of 1.6 and 22 mg/liter, respectively. Upward migration of dissolved manganese from the brine leads to production of manganese-rich particles in the slightly oxygenated overlying water. 相似文献
93.
94.
It has long been recognized that the Pu4+ ion can be readily adsorbed on solid surfaces, but it has been assumed that the generally more abundant Pu(V)O2+ ion should have little affinity for surfaces. Our results indicate that Pu(V)O2+ can be adsorbed from dilute solutions and seawater on goethite, aragonite, calcite, and δ-MnO2. Adsorption on δ-MnO2 is severely depressed in seawater, probably as a result of site competition with seawater cations.The sorption behavior of PuO2+ is influenced by oxidation-reduction reactions occurring on the mineral surfaces. Adsorption on δ-MnO2 results in oxidation of adsorbed Pu(IV) and Pu(V) to Pu(VI). However, adsorption on goethite results in a reaction in which Pu(IV) and Pu(VI) are formed on the mineral surface. The Pu(VI) is slowly reduced to Pu(IV), leaving Pu(IV) as the dominant surface Pu species. This reaction can be photochemically catalyzed. PuO2+ adsorbed on carbonate minerals behaves similarly to Np(V)O2+ and undergoes little change in oxidation state after adsorption. 相似文献
95.
Wendy J. Harrison 《Geochimica et cosmochimica acta》1981,45(9):1529-1544
Partition coefficients for the rare earth elements (REE) Ce, Sm and Tm between coexisting garnets and hydrous liquids have been determined at high pressure and temperatures (30 kbar and 1300 and 1500°C). Two synthetic systems were studied, Mg3Al2Si3O12-H2O and Ca3Al2Si3O12-H2O, in addition to a natural pyrope-bearing system.Deviations from Henry's Law behaviour occur at geologically relevant REE concentrations. At concentrations < 3 ppm Ce, < 12 ppm Sm, < 80 ppm Tm in pyrope and < 100 ppm Ce, < 250 ppm Sm, < 1000 ppm Tm in grossular (at 30 kbar and 1300°C), Dgarnet liquidREE increases as the REE concentration in the garnet decreases. At higher concentrations, DREE is constant. Dgrossular liquidREE also constant when the garnet contains less than about 2 ppm Sm or Tm. The REE concentration at which DREE becomes constant increases with increasing temperature, decreasing REE ionic radius and increasing Ca content of the garnet.Partitioning behaviour of Ce, Sm and Tm between a natural pyrope-rich garnet and hydrous liquid is analogous to that in the synthetic systems and substantiates the substitution model proposed by Harrison and Wood (1980).Values of DREEgarnet/liquid for which Henry's Law is obeyed are systematically higher for grossular than for pyrope (Dpyrope/liquid = 0.067(Ce), 0.108(Sm), 0.155(Tm) and Dgrossular/Liquid = 0.65(Ce), 0.75(Sm), 4.55(Tm).The implications of non-Henry's Law partitioning of REE for models of basalt petrogenesis involving garnet are far-ranging. Deviations from Henry's Law permit refinements to be made to calculated REE abundances once basic model parameters have been defined. 相似文献
96.
This article examines household-level characteristics that predict water insecurity in low-income rural and periurban communities on the Texas–Mexico border. We employ two logistic regression models (binary and ordered) to identify household characteristics that are more likely to result in water insecurity. Our analyses yielded unexpected findings: Whereas socioeconomic factors are weak predictors, immigration status of household members is a significant variable that contributes to household water insecurity. Policymakers need to pay more attention to marginalized communities as “universal” water access still leaves populations without adequate, reliable, and affordable water in the Global North. 相似文献
97.
Natural Hazards - A scientific hazard zoning of debris flows can ensure that human activities are not performed therein, thereby reducing economic loss as much as possible. In this study, by... 相似文献
98.
99.
Tropical Hong Kong: Narratives of absence and presence in Hollywood and Hong Kong films of the 1950s and 1960s 总被引:1,自引:1,他引:0
Wendy Gan 《Singapore journal of tropical geography》2008,29(1):8-23
Despite being subtropical, Hong Kong, in both Hollywood and Hong Kong films of the 1950s and 1960s, is often filmically represented as tropical. This subtle climatic elision, I argue, holds a particular political valence that varies according to filmic tradition. In Hollywood narratives, Hong Kong's tropicality is a means to exoticize and, ultimately, marginalize the realities of the local. It is a way to turn Hong Kong's physical presence into an absence. In Hong Kong films in that same cold war environment, the relative blandness of the city is an attempt to realign its film industry with the free nations of Southeast Asia. For Hong Kong films, the strategy of tropicalization was thus a means to turn away from China and redefine Hong Kong as part of a network of capitalist, modern, overseas Chinese cities located in the sunny tropics of Southeast Asia. 相似文献
100.
Natural Hazards - Disaster risk reduction should anticipate how future natural hazard risk would be influenced by changes in urban vulnerability. This paper investigates the effect of one key... 相似文献