Showing papers by "David Wong published in 2003"
TL;DR: This paper describes a recent effort to implement a set of spatial segregation measures in a GIS environment and an integrative approach is adopted to take advantage of various recent advances in GIS technology.
94 citations
TL;DR: In this article, the authors investigate dimensions of geographic variation in spatial dependency contained within large multilevel data sets and calculate 1990 population density by census block group, county, and state for the 48 coterminous states and the District of Columbia of the United States, exploring relations between these levels and their variation across the nation.
Abstract: The objective of this research is to investigate dimensions of geographic variation in spatial dependency contained within large multilevel data sets. We calculate 1990 population density by census block group, county, and state for the 48 coterminous states and the District of Columbia of the United States, calculations of interest to a wide variety of spatial scientists. We explore relations between these levels and their variation across the nation. The empirical findings generated by this work furnish implications concerning the Modifiable Areal Unit Problem (MAUP), spatial autocorrelation statistics, scale effects, and resolution.
48 citations
Journal Article•
TL;DR: SPARC protein appears to have an inhibitory effect on HRPE-mediated contraction of 2D collagen matrices, which may indicate a role for SPARC in modifying HRPE cell activities during the development of PVR and other proliferative retinal diseases.
Abstract: Purpose: To determine the effects of the matricellular protein SPARC (Secreted Protein, Acidic and Rich in Cysteine) on human retinal pigment epithelial (HRPE) cell behavior in vitro. Methods: Proliferation and migration assays were performed on HRPE cells exposed to various concentrations of SPARC. Additionally, HRPE cells were seeded on top of collagen matrices (a 2D model of the retinal scarring disorder known as proliferative vitreoretinopathy or PVR) and were exposed to SPARC over a 7 day period. Changes in matrix contraction were recorded. Results: HRPE cell proliferation was significantly inhibited at 1 and 10 ∝g/ml SPARC (p<0.01). SPARC protein did not stimulate HRPE cell migration at any of the concentrations used. SPARC did not significantly affect fibronectin-induced HRPE cell migration at SPARC concentrations up to 10 ∝g/ml. HRPE cell-seeded collagen matrices demonstrated a significant inhibition of matrix contraction by 1 and 10 ∝g/ml SPARC (t-test; p<0.02 and 0.001, respectively) compared to controls. Conclusions: SPARC protein has anti-proliferative effects on HRPE cells in vitro. In addition, SPARC appears to have an inhibitory effect on HRPE-mediated contraction of 2D collagen matrices. These results are consistent with an important role for SPARC in modulating cell behavior in vitro and may indicate a role for SPARC in modifying HRPE cell activities during the development of PVR and other proliferative retinal diseases.
11 citations
14 Mar 2003
Abstract: Virginia Access (VAccess) is a regional, remote sensing and Geographical Information Sciences project among several educational institutions. It is a prototype for regional projects in other states and other countries, and is funded by NASA's applications program. The user communities VAccess serves are the Commonwealth of Virginia and State of Maryland, local and regional users represented in a Technical Advisory Committee. Remote sensing data include global NASA and NOAA data tailored for regional applications as well as high-resolution multispectral (Landsat, MODIS, etc.), hyperspectral, LIDAR and SAR data sets. Broad beam LIDAR technology can provide canopy structure as well as other information for environmental concerns such as the state of wetlands. The data information system is based on a distributed architecture to serve remote sensing and GIS data to a variety of users via the WWW. Several remote sensing and GIS-based environmental and Earth systems science applications projects are discussed here, including flood and fire hazard mitigation, forestry, land use/land cover and epidemiology projects; as well as innovative data fusion, data access and analysis and various tools serving the users and their applications.
1 citations
TL;DR: This paper argues that Geographic Information Systems and related technologies are potentially very useful for environment risk assessment (ERA) in exploring the spatial relationships between various environmental risk factors and the condition and characteristics of the population.
Abstract: This paper argues that Geographic Information Systems (GIS) and related technologies are potentially very useful for environment risk assessment (ERA) in exploring the spatial relationships between various environmental risk factors and the condition and characteristics of the population. A framework is proposed to suggest how GIS can be used in ERA for all segments of the population, including children. Several GIS analytical functions, which are most useful for ERA, are reviewed and illustrated either by existing studies or examples. The paper also points out that no matter how powerful GIS may be, they are still exploratory tools to screen for relationships to be investigated further by clinical or experimental studies. By no means GIS alone can confirm the presence of an environmental risk factor and establish its relationship to a human biological reaction. The paper also highlights two difficult issues, spatial autocorrelation, and scale-dependency, in conducting spatial data analysis. Because the l...