共查询到20条相似文献,搜索用时 31 毫秒
1.
Barbara P. Buttenfield 《International journal of geographical information science》2013,27(5):661-665
In this article, we present a geographically explicit agent-based model (ABM), loosely coupled with vector geographical information systems (GISs), which explicitly captures and uses geometric data and socioeconomic attributes in the simulation process. The ability to represent the urban environment as a series of points, lines, and polygons not only allows one to represent a range of different-sized features such as buildings or larger areas portrayed as the urban environment but is a move away from many ABMs utilizing GIS that are rooted in grid-based structures. We apply this model to the study of residential segregation, specifically creating a Schelling (1971) type of model within a hypothetical cityscape, thus demonstrating how this approach can be used for linking vector-based GIS and agent-based modeling. A selection of simulation experiments are presented, highlighting the inner workings of the model and how aggregate patterns of segregation can emerge from the mild tastes and preferences of individual agents interacting locally over time. Furthermore, the article suggests how this model could be extended and demonstrates the importance of explicit geographical space in the modeling process. 相似文献
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The stable isotopic records of ostracode valves deposited during the last interglaciation in Raymond Basin, Illinois, have 13C and 18O values as high as +16.5 and +9.2 respectively, the highest values yet reported from continental ostracodal calcite. Located in south-central Illinois, Raymond, Pittsburg, Bald Knob, and Hopwood Farm basins collectively have yielded important long pollen and ostracode records that date from about 130000 years ago to the present. Although fossils from the present-day interglaciation are not well preserved, these records constitute the only described, conformable, fossiliferous successions of this age from the interior of glaciated North America.The high 13C values from Raymond Basin are attributed to the residual effects of methane loss either by ebullition or by emission through the stems of senescent emergent aquatic vegetation. A mass balance model suggests that an increase in 13C of dissolved inorganic carbon on the order of +15 is possible within a few hours given modest rates of methanogenesis of about 0.02 mol m-2 d-1. The 13C records from other studies of ostracode valves have values approaching, but not exceeding about +14 suggesting a limiting value to 13C enrichment due to simultaneous inputs and outputs of dissolved inorganic carbon.Values of 18O in ostracodal calcite are quite variable (–4 to +9) in sediment from the late Sangamon subepisode. A model of isotopic enrichment in a desiccating water body implies that a reduction in reservoir volume of 20% could produce this range of isotopic values. High humidity and evaporation probably account for most of the 18O variability. 相似文献
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Over the past three decades, feminist historiography of geography has begun to situate women's contribution to the production of geographical knowledge within the histories of geography, at times against the conviction of skeptical colleagues. In this Focus Section introduction, we renew Domosh's (1991a, 1991b) call for creating more inclusive feminist histories of geography by situating the three focus section articles on the careers and contributions of women in twentieth-century geographical practice and knowledge production in the United Kingdom and the United States within wider debates about diverse, unfamiliar, and previously hidden aspects of geographical knowledge production. We argue that feminist historiography of geography and feminist historical geography could benefit from continuously diversifying inclusive and comparative research perspectives, and from unlocking diverse archives, to enhance understanding of why and how some male and some female gatekeepers have been more supportive of women than others. 相似文献
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Zhenhong Du Zhongyi Wang Sensen Wu Feng Zhang Renyi Liu 《International journal of geographical information science》2020,34(7):1353-1377
ABSTRACT Geographically weighted regression (GWR) is a classic and widely used approach to model spatial non-stationarity. However, the approach makes no precise expressions of its weighting kernels and is insufficient to estimate complex geographical processes. To resolve these problems, we proposed a geographically neural network weighted regression (GNNWR) model that combines ordinary least squares (OLS) and neural networks to estimate spatial non-stationarity based on a concept similar to GWR. Specifically, we designed a spatially weighted neural network (SWNN) to represent the nonstationary weight matrix in GNNWR and developed two case studies to examine the effectiveness of GNNWR. The first case used simulated datasets, and the second case, environmental observations from the coastal areas of Zhejiang. The results showed that GNNWR achieved better fitting accuracy and more adequate prediction than OLS and GWR. In addition, GNNWR is applicable to addressing spatial non-stationarity in various domains with complex geographical processes. 相似文献
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Yuanyang Lake (24°35N, 121°24E), located at an altitude of 1,670 m within a nature preserve in northern Taiwan, is an acidic lake. Remains of diatoms and pollen from a 3.72-m sediment core were used to elucidate the relationships between the vegetation of the watershed and the paleolimnological environment. Past pH, saprobity level, and total P of the lake were inferred from the diatom assemblages and were analyzed with respect to changes in the terrestrial vegetation. The inferred pH values fluctuated only slightly, whereas the inferred saprobity level increased markedly towards the sediment surface. In the topmost sediment, a slight drop in the inferred pH was associated with a lowering in the saprobity index. This was interpreted as a possible result of recent anthropogenic acidification and changes in productivity related to changes in acidity. Based on pollen analyses, we conclude that Chamaecyparis persisted over at least the last four thousand years in the watershed. The vegetation in the watershed changed little during this period of time, which is consistent with the constancy of inferred pH values. A positive correlation between the inferred pH and 13C values of the sediments was found. 相似文献
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Matthias Templ Beat Hulliger Alexander Kowarik Karin Fürst 《International journal of geographical information science》2013,27(4):685-698
The checkerplot is a new type of graphical display that combines geographical information and statistical plots. Hereby, the traditional plots like barplots or polygon lines are visualized in geographical order on a grid. The checkerplots can be seen as a mixture between thematic maps and the grid representation in trellis plots. In a checkerplot, any complex statistical graphics that are produced for geographical areas are placed in a grid. An interpretable checkerplot requires an arrangement of areas on the grid that reflects the underlying geography. A loss function is proposed that represents the distortion of the underlying geography needed in order to place the areas onto a grid. It is demonstrated that the minimization of the loss function does indeed produce interpretable checkerplots. Moreover, the optimization problem can be formulated as a linear programming problem that can be solved using standard linear programming solvers. The proposed checkerplot is applied to US health insurance data to analyze the development of the coverage rate in the health system per state with respect to the different health care programs. Moreover, an example related to the EU-member states is also given. Additional information like the national flags of countries are placed in each grid to allow better visibility and recognition of the countries. The checkerplot is implemented in the R-package sparkTable (Kowarik, Meindl, and Templ, 2012. sparkTable: sparklines and graphical tables for tex and html [online]. R package version 0.9.3 [Accessed 7 February 2012]) and can be freely downloaded from the CRAN repository. It is implemented in a flexible manner and not restricted to the examples given in this contribution. 相似文献
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Kirti K. Lal 《The Australian geographer》2011,42(1):41-51
For the first time, a sediment core spanning the entire Holocene has been analysed from Fiji. The 6 m core was obtained from the floor of an ancient coastal lagoon (palaeolagoon) adjacent to Bourewa, the site of the earliest known human settlement in this island group. The basal sediments, just above bedrock, date from 11 470 cal bp. A major transition occurs around 8000 cal bp where marine influences on palaeolagoon sedimentation increase sharply. Full shallow-water marine conditions are attained around 4630 cal bp and last until 3480 cal bp after which there is a regressive phase. The results agree with the area-specific predictions of sea level in the ICE-4G model, particularly in the timing of the highstand. In addition, the results support the ideas (a) that early human colonisation of Fiji occurred during the late Holocene regression, (b) that the first inhabitants of Bourewa utilised both nearshore marine (reefal) and brackish lagoon food sources, and (c) that the abrupt human abandonment of the area around 2500 cal bp could have been prompted by a reduction in these resources driven largely by sea-level fall. 相似文献
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Cidália Costa Fonte Weldon A. Lodwick 《International journal of geographical information science》2013,27(2):127-150
Fuzzy Geographical Entities (FGEs) refer in this paper to geographical entities with fuzzy spatial extent. The use of FGEs in geographical information systems requires the existence of operators capable of processing them. In this paper, our contribution to that field focuses on the computation of areas. Two methods are considered, one crisp due to Rosenfeld (1984), which has limited applicability, and the other fuzzy, which is a new approach. The new fuzzy area operator gives more information about the possible values of the area and enables the fuzziness in the spatial extent of the entity to be propagated to the area. Crisp and fuzzy areas have different meanings, and the use of one or the other depends not only on the purpose of the computation but also on the semantics of the membership functions. When the FGEs are represented by normal fuzzy sets, the fuzzy area operator generates fuzzy numbers, and therefore arithmetic operations can be performed with them using fuzzy arithmetic. However, we show that care must be taken with the use of the fuzzy arithmetic operators because, in some situations, the usual operators should not be applied. Properties of the Rosenfeld and fuzzy area operators are analysed, establishing a parallel with properties of the areas of crisp sets. 相似文献
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Detailed knowledge about the estimates and spatial patterns of soil organic carbon (SOC) and total nitrogen (TN) stocks is fundamental for sustainable land management and climate change mitigation. This study aimed at: (1) mapping the spatial patterns, and (2) quantifying SOC and TN stocks to 30 cm depth in the Eastern Mau Forest Reserve using field, remote sensing, geographical information systems (GIS), and statistical modelling approaches. This is a critical ecosystem offering essential services, but its sustainability is threatened by deforestation and degradation. Results revealed that elevation, silt content, TN concentration, and Landsat 8 Operational Land Imager band 11 explained 72% of the variability in SOC stocks, while the same factors (except silt content) explained 71% of the variability in TN stocks. The results further showed that soil properties, particularly TN and SOC concentrations, were more important than that other environmental factors in controlling the observed patterns of SOC and TN stocks, respectively. Forests stored the highest amounts of SOC and TN (3.78 Tg C and 0.38 Tg N) followed by croplands (2.46 Tg C and 0.25 Tg N) and grasslands (0.57 Tg C and 0.06 Tg N). Overall, the Eastern Mau Forest Reserve stored approximately 6.81 Tg C and 0.69 Tg N. The highest estimates of SOC and TN stocks (hotspots) occurred on the western and northwestern parts where forests dominated, while the lowest estimates (coldspots) occurred on the eastern side where croplands had been established. Therefore, the hotspots need policies that promote conservation, while the coldspots need those that support accumulation of SOC and TN stocks. 相似文献
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Mark Brenner Thomas J. Whitmore Jason H. Curtis David A. Hodell Claire L. Schelske 《Journal of Paleolimnology》1999,22(2):205-221
We explored the use of carbon and nitrogen isotopes (13C and 15N) in sedimented organic matter (OM) as proxy indicators of trophic state change in Florida lakes. Stable isotope data from four 210Pb-dated sediment cores were compared stratigraphically with established proxies for historical trophic state (diatom-inferred limnetic total phosphorus, sediment C/N ratio) and indicators of cultural disturbance (sediment total P and 226Ra activity). Diatom-based limnetic total P inferences indicate a transition from oligo-mesotrophy to meso-eutrophy in Clear Lake, and from eutrophy to hypereutrophy in Lakes Parker, Hollingsworth and Griffin. In cores from all four lakes, the carbon isotopic signature of accumulated OM generally tracks trophic state inferences and cultural impact assessments based on other variables. Oldest sediments in the records yield lower diatom-inferred total limnetic P concentrations and display relatively low 13C values. In the Clear, Hollingsworth and Parker records, diatom-inferred nutrient concentrations increase after ca. AD 1900, and are associated stratigraphically with higher 13C values in sediment OM. In the Lake Griffin core, both proxies display slight increases before ~1900, but highest values occur over the last ~100 years. As Lakes Clear, Hollingsworth and Parker became increasingly nutrient-enriched over the past century, the 15N of sedimented organic matter decreased. This reflects, in part, the increasing relative contribution of nitrogen-fixing cyanobacteria to sedimented organic matter as primary productivity increased in these waterbodies. The Lake Griffin core displays a narrow range of both 13C and 15N values. Despite the complexity of carbon and nitrogen cycles in lakes, stratigraphic agreement between diatom-inferred changes in limnetic total P and the stable isotope signatures of sedimented OM suggests that 13C and 15N reflect shifts in historic lake trophic state. 相似文献
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Gail Christine Potgieter Florian Johannes Weise Bettina Wachter Jörg Melzheimer Ingrid Wiesel Ken Stratford 《社会与自然资源》2017,30(10):1299-1303
Carnivore conservationists agree that addressing the socioeconomic needs of people is critical to human-carnivore conflict mitigation. We therefore welcome studies that encompass complex social and cultural factors that affect the severity of human-carnivore conflict on Namibian farmlands. However, we contend that the recent study by Rust et al. (2016) was poorly designed, used inappropriate sampling methods, lacked quantitative information on their qualitative results, and ultimately produced unsupported conclusions about the role of historic apartheid and current racism in exacerbating human-carnivore conflict in Namibia. We outline our concerns regarding the methods used, and demonstrate that the conclusions drawn by Rust et al. were not supported by their data. 相似文献
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Jarmo J. Meriläinen Juhani Hynynen Arja Palomäki Pasi Reinikainen Anssi Teppo Kaj Granberg 《Journal of Paleolimnology》2000,24(3):251-270
The recent environmental history of Lake Lappajärvi in western Finland (63°00 N, 23°30 E, area 149 km2), a humic, brown water lake with an average phosphorus content of ca. 20 g l–1, was studied from short core sediment samples taken from the two main basins of the lake. Based on the stratigraphy of diatoms and chironomids and the sediment quality it was possible to distinguish four developmental stages during the past century: (1) a pre-industrial stage covering the time up to about 1935; (2) a stage of increasing nutrient loading (ca. 1936–1960); (3) a stage of pronounced erosion from lake level regulation and extensive ditching of the catchment area (ca. 1960–1970); and (4) a meso-eutrophic stage from ca. 1970 onwards.Acidophilous Aulacoseira distans coll. and other species typical of dystrophic, nutrient-poor lakes characterized the diatom assemblages during the first stage, and the profundal zoobenthic assemblages, characterized by Heterotrissocladius subpilosus and Micropsectra, indicated good hypolimnetic oxygen conditions and a low sedimentation of organic matter (approx. less than 50 g m–2 a–1). The increased loading rapidly led to changes both in diatoms and chironomids (e.g., to an early extinction of H. subpilosus in the 1950s). The process finally led to eutrophication with a successive proliferation of diatom species such as Asterionella formosa followed by Aulacoseira ambigua, Fragilaria crotonensis, and finally Melosira varians. The relative proportion of alkaliphilous species reached a maximum in the final stage and the original profundal chironomid fauna was replaced by Chironomus anthracinus gr. and C. plumosus which are typical of profundal areas suffering from temporal oxygen deficit. It is notable that the considerable decrease in waste water loading from the point sources (80–86% ) during the past two decades has not led to a recovery in the lake. This highlights the importance of diffuse loading from agriculture, forestry and other human activities even to this comparatively large lake. 相似文献
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C. D. Lloyd 《International journal of geographical information science》2013,27(8):1193-1221
Information on how populations are spatially concentrated by different characteristics is a key means of guiding government policies in a variety of contexts, in addition to being of substantial academic interest. In particular, to reduce inequalities between groups, it is necessary to understand the characteristics of these groups in terms of their composition and their geographical structure. This article explores the degree to which the population of Northern Ireland is spatially concentrated by a range of characteristics. There is a long history of interest in residential segregation by religion in Northern Ireland; this article assesses population concentration not only by community background (‘religion or religion brought up in’) but also by housing tenure, employment and other socioeconomic and demographic characteristics. The spatial structure of geographical variables can be captured by a range of spatial statistics including Moran's I. Such approaches utilise information on connections between observations or the distances between them. While such approaches are conceptually an improvement on standard aspatial statistics, a logical further step is to compute statistics on a local basis on the grounds that most real-world properties are not spatially homogenous and, therefore, global measures may mask much variation. In population geography, which provides the substantive focus for this article, there are still relatively few studies that assess in depth the application of geographically weighted statistics for exploring population characteristics individually and for exploring relations between variables. This article demonstrates the value of such approaches by using a variety of geographically weighted statistical measures to explore outputs from the 2001 Census of Population of Northern Ireland. A key objective is to assess the degree to which the population is spatially divided, as judged by the selected variables. In other words, do people cluster more strongly with others who share their community background or others who have a similar socioeconomic status in some respect? The analysis demonstrates how geographically weighted statistics can be used to explore the degree to which single socioeconomic and demographic variables and relations between such variables differ at different spatial scales and at different geographical locations. For example, the results show that there are regions comprising neighbouring areas with large proportions of people from the same community background, but with variable unemployment levels, while in other areas the first case holds true but unemployment levels are consistently low. The analysis supports the contention that geographical variations in population characteristics are the norm, and these cannot be captured without using local methods. An additional methodological contribution relates to the treatment of counts expressed as percentages. 相似文献
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We report oxygen isotope data from a 108-yr (1885–1993) sequence with annual laminae of bio-induced authigenic calcite in a frozen core from Baldeggersee, a small lake in Central Switzerland. These isotope results provide proxy data on the isotopic composition of past precipitation in the Baldeggersee catchment region and are quantitatively compared with instrumental climate data (i.e. mean annual air temperature and atmospheric circulation pattern indices) to evaluate climatic controls on oxygen isotopes in precipitation.Monitoring the isotope hydrology of Baldeggersee demonstrates that the oxygen isotopic composition of the lake water is controlled by the isotopic composition of local atmospheric precipitation (18Op) and that the isotopic signal of precipitation is preserved, albeit damped, in the lake calcite oxygen isotope record (18Oc). Comparison of the calcite oxygen isotope proxy for 18Op in the catchment with historical mean annual air temperature measurements from Bern, Switzerland confirms that authigenic calcite reliably records past annual air temperature in the region. This 18Oc/temperature relationship is calculated to be 0.39/°C for the period 1900–1960, based on an isotope mass-balance model for Baldeggersee. An exception is a 0.8 anomalous negative shift in calcite 18O values since the 1960s. Possible explanations for this recent 18Oc shift, as it is not related to mean annual air temperature, include changes in 18Op due to synoptic circulation patterns. In particular, the 0.8 negative shift coincides with a trend towards a more dominant North Atlantic Oscillation (NAO) index. This circulation pattern would tend to bring more isotopically more negative winter precipitation to the region and could account for the 0.8 offset in 18Oc data. 相似文献
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河南农区经济发展差异地理影响的小尺度分析 总被引:26,自引:2,他引:24
对中国第一农业大省河南的乡镇数据分析表明, 地理因素对农区经济发展具重要影响。 在较低经济发展水平的乡镇, 地形和农业资源条件具有显著的影响; 而在相对较高经济发展 水平的乡镇, 地理位置以及与此相伴生的基础设施条件的影响更为显著。模型分析表明, 地 形显著影响乡镇的人均收入, 而且随着收入的增加, 其影响程度递减。人均土地面积显著影 响非农产业发展水平较低的乡镇的人均收入。对非农产业比重低于20%的乡镇, 人均土地每 增加1 hm2, 人均收入就增加约96 元。地理位置影响着相关农区经济的发展, 尤其是对收入 较高的农区的影响十分明显。全省高收入乡镇的70%集中在河南中部地区, 正好与中原城市 群的空间范围相吻合。就单个乡镇而论, 离县城的距离显著影响高收入乡镇的人均收入。地 理因素对欠发达农区经济发展影响处于变动之中。随着经济水平的提高, 传统地理因素(如 地形、农业资源因素等) 的影响逐渐被对经济积聚有明显影响的地理临近性等要素的影响所 取代。因此, 不能简单的认为地理因素对经济发展的影响在下降。 相似文献
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Anthropogenic nitrogen deposition induces rapid ecological changes in alpine lakes of the Colorado Front Range (USA) 总被引:7,自引:3,他引:7
Recent sediments from two alpine lakes (> 3300 m asl) in the Colorado Front Range (USA) register marked and near-synchronous changes that are believed to represent ecological responses to enhanced atmospheric deposition of fixed nitrogen from anthropogenic sources. Directional shifts in sediment proxies include greater representations of mesotrophic diatoms and increasingly depleted 15N values. These trends are particularly pronounced since ~ 1950, and appear to chronicle lake responses to excess N derived from agricultural and industrial sources to the east. The rate and magnitude of recent ecological changes far exceed the context of natural variability, as inferred from comparative analyses of a long core capturingthe entire 14,000-year postglacial history of one of the lakes. Nitrogen deposition to these seemingly pristine natural areas has resulted in subtle but detectable limnological changes that likely represent the beginning of a stronger response to nitrogen enrichment. 相似文献
19.
Erik Jönsson 《社会与自然资源》2017,30(7):844-859
ABSTRACTIn this article, I scrutinize three art, design, and architecture projects engaging with “cultured,” or “in vitro,” meat (primarily muscle cells cultured outside of bodies) to illuminate the entanglements of academic and extra-academic environments that have characterized cultured meat’s history to date, and the conversations that this technology has spurred. In envisioning new ways of eating, and living, these projects (a book of hypothetical recipes, The In Vitro Meat Cookbook, Catts and Zurr’s bioartistic engagements with tissue engineering, and Terreform1’s tissue-house prototype “The In Vitro Meat Habitat”) illustrate cultural practices thought to be enabled by cell culturing’s new applications. Emphasizing such visions and conversations allows me to highlight an inattention to discursive dynamics within research on natures subsumed to industrial production processes (Boyd, Prudham, and Schurman 2001). But engaging with the “subsumption of nature” framework simultaneously allows me to problematize artistic visions presenting nature as fully malleable. 相似文献