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61.
Abstract

Industrial land development has become a key feature of urbanization in Greater Jakarta, one of the largest metropolitan areas in Southeast Asia. Following Suharto's market-oriented policy measures in the late 1980s, private developers have dominated the land development projects in Greater Jakarta. The article investigates the extent to which these private industrial centers have effectively reduced the domination of Jakarta in shaping the entire metropolitan structure. The analysis indicates that major suburban industrial centers have captured most of the manufacturing employment that has dispersed from Jakarta. The industrial centers have now increasingly specialized and diversified. It is likely that a polycentric metropolitan structure will emerge in the future.  相似文献   
62.
The conformal-cubic atmospheric model, a variable-resolution global model, is applied at high spatial resolution to perform simulations of present-day and future climate over southern Africa and over the Southwest Indian Ocean. The model is forced with the bias-corrected sea-surface temperatures and sea-ice of six coupled global climate models that contributed to Assessment Report 4 of the Intergovernmental Panel on Climate Change. All six simulations are for the period 1961–2100, under the A2 emission scenario. Projections for the latter part of the 21st century indicate a decrease in the occurrence of tropical cyclones over the Southwest Indian Ocean adjacent to southern Africa, as well as a northward shift in the preferred landfall position of these systems over the southern African subcontinent. A concurrent increase in January to March rainfall is projected for northern Mozambique and southern Tanzania, with decreases projected further south over semi-arid areas such as the Limpopo River Basin where these systems make an important contribution as main cause of widespread heavy rainfall. It is shown that the projected changes in tropical cyclone attributes and regional rainfall occur in relation to changes in larger scale atmospheric temperature, pressure and wind profiles of the southern African region and adjacent oceans.  相似文献   
63.
Many ecosystem services are in decline. Local ecological knowledge and associated practice are essential to sustain and enhance ecosystem services on the ground. Here, we focus on social or collective memory in relation to management practice that sustains ecosystem services, and investigate where and how ecological practices, knowledge and experience are retained and transmitted. We analyze such socialecological memory of allotment gardens in the Stockholm urban area, Sweden. Allotment gardens support ecosystem services such as pollination, seed dispersal and pest regulation in the broader urban landscape. Surveys and interviews were preformed over a four-year period with several hundreds of gardeners. We found that the allotment gardens function as communities-of-practice, where participation and reification interact and social–ecological memory is a shared source of resilience of the community by being both emergent and persistent. Ecological practices and knowledge in allotment gardens are retained and transmitted by imitation of practices, oral communication and collective rituals and habits, as well as by the physical gardens, artifacts, metaphors and rules-in-use (institutions). Finally, a wider social context provides external support through various forms of media, markets, social networks, collaborative organizations, and legal structures. We exemplify the role of urban gardens in generating ecosystem services in times of crisis and change and conclude that stewards of urban green areas and the social memory that they carry may help counteract further decline of critical ecosystem services.  相似文献   
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66.
Spatial dynamics of retail structure and the venerable retail hierarchy   总被引:1,自引:0,他引:1  
The retail system is continuously adapting itself to changing demographic conditions, consumer behavior and economic conditions. Existing retail units, getting larger in order to achieve economics of scale, and new forms of large-scale retailing do not fit easily in the traditional spatial pattern of retail concentrations. Neverteless the spatial distribution of retailing in urban areas, as schematized by Berry thirty-five years ago, still has its value. Through an upward hierarchical movement the retail system has adapted itself to an inflexible spatial system, in which downtown has still a dominant position. Future developments, however, may weaken the position of central shopping areas in favour of peripheral locations. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   
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The common assumption that the ratio between particulate organic carbon (POC) and particulate 234Th obtained from shallow sediment traps and filterable particles are representative of the ratio in the total particle settling flux should be treated with caution in view of well-known biases associated with tethered shallow sediment traps and the decoupling between size and settling velocity of many natural particle regimes. To make progress toward reliably constraining the POC / 234Th ratio on truly settling particles, we have tested here a settling collection technique designed to remove any hydrodynamic bias; split flow-thin cell fractionation (SPLITT). These first results from a North Sea fjord and an open Baltic Sea time-series station indicates that the POC / 234Th ratio on the more complete particle-settling spectrum, isolated with SPLITT, was higher than the POC / 234Th ratio obtained simultaneously from tethered shallow sediment traps in seven out of seven parallel deployments with an average factor of 210%. The POC / 234Th ratio from the SPLITT was either in the same range or higher than that obtained on filtered “bulk” particles. To explain this novel data we hypothesize that the slowest settling fraction is organic-matter rich and does not strongly complex 234Th (i.e., high POC / 234Th). We suggest that this ultra-slow sinking fraction is better collected by SPLITT than with tethered sediment traps because of minimized hydrodynamic bias.This was tested using the ratio of POC / Al as a tracer of detrital mineral-ballast influenced settling velocity. The higher POC / Al ratios in SPLITT samples relative to in traps is consistent with the hypothesis that SPLITT is better suited for collecting also the slow-settling component of sinking particles. This important slow-settling component appears to here consist primarily of non-APS/TEP components of plankton exudates or other less-strongly 234Th-complexing organic matter. Further applications of the SPLITT technique are likely to return increasingly new insights on the composition (including “truly settling” POC / 234Th) of the total spectrum of particles settling out of the upper ocean.  相似文献   
69.
The Markermeer is a large and shallow man-made freshwater lake in the Netherlands, characterized by its high turbidity. As part of a study aiming to mitigate this high turbidity, we studied the water–bed exchange processes of the lake’s muddy bed. The upper centimeter’s–decimeter’s of the lake bed sediments mainly consists of soft anoxic mud. Recent measurements have proved the existence of a thin oxic layer on top of this soft anoxic mud. This oxic layer, which is much easier to be eroded than the anoxic mud, is believed to be related with Markermeer’s high-turbidity levels. Our hypothesis is that the thin oxic layer develops from the anoxic mud, enhanced by bioturbation. Actually, we will demonstrate that it is the bioturbated state of the bed that increases its erodability, and not the oxidation state of the sediments. In particular, we will refer to bioturbation caused by meiobenthic fauna. The objective of this study is therefore to determine the influence of the development of the thin oxic layer on the water–bed exchange processes, as well as to establish the role of bioturbation on those processes. This is done by quantifying the erosion rate as a function of bed shear stresses, and at different stages of the development of the oxic layer. Our experiments show that bioturbation increases the rate at which Markermeer sediments are eroded by almost an order of magnitude. The short-term fine sediment dynamics in Markermeer are found to be driven by the complex and highly dynamic interactions between physics, chemistry, and biology. Finally, the long-term fine sediment dynamics are driven by the erosion of the historical deposits in the lake’s bed, which is only possible after bioturbation, and which leads to an increase of the stock of sediments in the lake’s muddy bed.  相似文献   
70.
The Liard Lobe formed a part of the north‐eastern sector of the Cordilleran Ice Sheet and drained ice from accumulation areas in the Selwyn, Pelly, Cassiar and Skeena mountains. This study reconstructs the ice retreat pattern of the Liard Lobe during the last deglaciation from the glacial landform record that comprises glacial lineations and landforms of the meltwater system such as eskers, meltwater channels, perched deltas and outwash fans. The spatial distribution of these landforms defines the successive configurations of the ice sheet during the deglaciation. The Liard Lobe retreated to the west and south‐west across the Hyland Highland from its local Last Glacial Maximum position in the south‐eastern Mackenzie Mountains where it coalesced with the Laurentide Ice Sheet. Retreat across the Liard Lowland is evidenced by large esker complexes that stretch across the Liard Lowland cutting across the contemporary drainage network. Ice margin positions from the late stage of deglaciation are reconstructed locally at the foot of the Cassiar Mountains and further up‐valley in an eastern‐facing valley of the Cassiar Mountains. The presented landform record indicates that the deglaciation of the Liard Lobe was accomplished mainly by active ice retreat and that ice stagnation played a minor role in the deglaciation of this region. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   
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