Decoding the Development Strategy of a Major Retailer: Wal-Mart's Expansion in the United States

This research aims to provide insight regarding Wal-Mart's retail development strategy in its expansion across the continental United States. The study examines store location patterns and relationships between Wal-Mart's store and distribution center locations and markets. The study shows that, although radial expansion is broadly characteristic of the dense store patterns that have been well established for Wal-Mart at the national level, expansion patterns at the regional level are consistent with a selective process based on factors other than store density. These results provide a new perspective on Wal-Mart's expansion, providing insights of value to retail practitioners and local government.     

Land Cover Change and its Environmental Significance in the Herbert River Catchment,North-east Queensland

There has been considerable recent concern over the amount of vegetation clearance in the wet tropics of northern Australia. This paper reports on the results of a case study undertaken in the lower Herbert River catchment in north-east Queensland, which utilised remote sensing and Geographic Information Systems (GIS) to assess both spatial and temporal changes in land cover since European settlement in the mid-nineteenth century. We demonstrate that since European settlement there has been a substantial reduction in the area of Melaleuca, rainforest, and eucalyptus-dominated land-cover patterns. We also provide a range of quantitative measures to show that the landscape diversity, integrity and quality of these ecosystems have also declined between the 1860s and 1996. We conclude that reform is required at policy, planning and enterprise levels if the ecological, economic and social values of these systems are to be maintained in the future.     

Advances in location modeling: GIS linkages and contributions

Geographic information systems (GIS) have matured and proven to be an enabling technology, one that is important to many disciplines. Location analysis is also a field that has matured and continues to evolve. In fact, the combination of GIS and location science is at the forefront of advances in spatial analysis capabilities, offering substantial potential for continued and sustained theoretical and empirical evolution. This paper provides an overview of location analysis and discusses GIS. The paper highlights how GIS has contributed to location science in terms of data input, visualization, problem solution and theoretical advances. The significance of GIS in this context is that it is far more than a mere spatial data input mechanism, which is a commonly held misconception within geography, operations research and other allied disciplines. In contrast to other reviews, the focus in this paper is to highlight the theoretical foundations of location analysis and modeling and how GIS is contributing to important advancements in this field. An overall contribution of the paper is providing a perspective on spatial analysis and how associated specialty areas are evolving and thriving, particularly as a component of GIScience.     

Luminescence dating of old (>70 ka) Chinese loess: A comparison of single-aliquot OSL and IRSL techniques

The applicability of two different approaches in the luminescence dating of old (>70 ka) Chinese loess is investigated. Both SAR-OSL ages obtained on 63–90 μm quartz grains and SAR-IRSL ages obtained on 4–11 μm polymineral grains, for samples collected from two sites in the Chinese Loess Plateau (Luochuan and Dongchuan) are presented. The characteristics of the luminescence signals stimulated by blue and infrared light are investigated in terms of dose response and dose recovery, and as a function of age. Additionally, anomalous fading measurements from the 410 nm IRSL emission in polymineral fine-grains are reported. An average value of g_2days amounting to 3% per decade was measured and seems to be independent of site location and age. For the samples from Luochuan, independent age control (pedostratigraphy and palaeomagnetism) is available. At both sites, the SAR-OSL ages are always lower than the SAR-IRSL ages after they have been corrected for anomalous fading. It seems that the quartz-based SAR-OSL ages are accurate for the younger ages, but that they underestimate the true age of deposition for loess that was deposited about 60–70 ka ago. The fading-corrected SAR-IRSL ages are in better agreement with the pedostratigraphic age control (75 and 130 ka) and allow dating beyond the quartz OSL range. Based on our results, we suggest that conventional SAR-OSL and SAR-IRSL protocols at these sites should be restricted to samples of ages not exceeding 40–50  and 100–120 ka, respectively.     

Groundwater biofilm dynamics grown in situ along a nutrient gradient

This paper describes the in situ response of groundwater biofilms in an alluvial gravel aquifer system on the Canterbury Plains, New Zealand. Biofilms were developed on aquifer gravel, encased in fine mesh bags and suspended in protective columns in monitoring wells for at least 20 weeks. Four sites were selected in the same groundwater system where previous analyses indicated a gradient of increasing nitrate down the hydraulic gradient from Sites 1 to 4. Measurements during the current study classified the groundwater as oligotrophic. Biofilm responses to the nutrient gradients were assessed using bioassays, with biomass determined using protein and cellular and nucleic acid staining and biofilm activity using enzyme assays for lipid, carbohydrate, phosphate metabolism, and cell viability. In general, biofilm activity decreased as nitrate levels increased from Sites 1 to 4, with the opposite relationship for carbon and phosphorus concentrations. These results showed that the groundwater system supported biofilm growth and that the upper catchment supported efficient and productive biofilms (high ratio of activity per unit biomass).     

Economic consequences of consideration of permanence, leakage and additionality for soil carbon sequestration projects

This paper introduces, explains, and describes methods for addressing the issues of permanence, leakage, and additionality (PLA) of agricultural soil carbon sequestration (ASCS) activities at the project level. It is important to cast these as project-level issues, because they relate to the integrity and consistency of using location-specific ASCS projects as an offset against GHG emissions generated in other sectors (e.g., energy). The underlying objective is to understand and quantify what the net carbon benefits of an ASCS project are once we account for the fact that (1) the sequestered carbon may be stored impermanently, (2) the project may displace emissions outside the project boundaries (leakage), and (3) the project’s carbon sequestration may not be entirely additional to what would have occurred anyway under business-as-usual (no project) conditions. This article evaluates methods for identifying and estimating PLA and gauges the potential magnitude of these effects on the economic returns to a project. This work reflects ongoing collaborative efforts of the authors and Bruce McCarl (Texas A&M University), Allan Sommer, Jui-Chen Yang, and Laurel Clayton (RTI International), Sandra Brown (Winrock International), Ken Andrasko and Ben DeAngelo (US EPA), and various participants in the World Resources Institute/World Business Council workgroup to develop GHG project reporting protocols. All opinions, errors and omissions are those of the authors only.     

Evaluating the impact of caprock and reservoir properties on potential risk of CO2 leakage after injection

Numerical models are essential tools in fully understanding the fate of injected CO₂ for commercial-scale sequestration projects and should be included in the life cycle of a project. Common practice involves modeling the behavior of CO₂ during and after injection using site-specific reservoir and caprock properties. Little has been done to systematically evaluate and compare the effects of a broad but realistic range of reservoir and caprock properties on potential CO₂ leakage through caprocks. This effort requires sampling the physically measurable range of caprock and reservoir properties, and performing numerical simulations of CO₂ migration and leakage. In this study, factors affecting CO₂ leakage through intact caprocks are identified. Their physical ranges are determined from the literature from various field sites. A quasi-Monte Carlo sampling approach is used such that the full range of caprock and reservoir properties can be evaluated without bias and redundant simulations. For each set of sampled properties, the migration of injected CO₂ is simulated for up to 200 years using the water–salt–CO₂ operational mode of the STOMP simulator. Preliminary results show that critical factors determining CO₂ leakage rate through caprocks are, in decreasing order of significance, the caprock thickness, caprock permeability, reservoir permeability, caprock porosity, and reservoir porosity. This study provides a function for prediction of potential CO₂ leakage risk due to permeation of intact caprock and identifies a range of acceptable seal thicknesses and permeability for sequestration projects. The study includes an evaluation of the dependence of CO₂ injectivity on reservoir properties.     

Source localization with broad-band matched-field processing inshallow water

Acoustic source localization using matched-field processing is presented for multitone signals from the Shallow Water Evaluation cell Experiment 3 (SWellEX-3). The experiment was carried out in July 1994 west of Point Loma, CA, in 200 m of water of complex bathymetry. The multitone signal (ten tones between 50 and 200 Hz) was transmitted from an acoustic source towed at various depths over tracks which produced complex propagation paths to a vertical line array receiver. Broad-band and narrow-hand processing, localization, and tracking results are compared with each other and with independent estimates of source position. With narrow-band processing, mismatch between the data and the predicted signal replica of ~1 dB reduced the mainlobe to levels equal to or below the sidelobes. Incoherently averaging the processing output over the multiple tones reduced range/depth sidelobe levels, allowing accurate source localization and tracking