Research , Grants and Presentations
Recent Refereed Journal
Articles
Wang, F. and W.
Luo, 2005, “Assessing Spatial and Nonspatial Factors for Healthcare
Access in Illinois: Towards an Integrated Approach to Defining Health Professional
Shortage Areas,” Health and Place, v. 11, n. 2, p. 131-146
Abstract
Wang, F. and W. Luo, 2005, “GIS-Based Accessibility Measures and Application,” in “Encyclopedia of Information Science and Technology,” M. Khosrow-Pour (ed), Idea Group Reference, Hershey, PA. Refereed.
Luo, W. and J. M. Harlin, 2004, “Reply to discussion by Athanasios N. Papanicolaou and Ahmed Bdour, ‘A Theoretical Travel Time Based on Watershed Hypsometry’”, Journal of American Water Resources Association,v. 40, n. 5, p. 1388.
Luo, W., F. Wang, and C. Douglass, 2004, “Temporal Changes of Access to Primary Health Care in Illinois (1990-2000) and Policy Implications,” Journal of Medical Systems. v. 28, n. 3, p. 287-299. Abstract
Luo, W., K.L. Duffin, E. Peronja, J.A. Stravers, and G.M. Henry, 2004, “A Web-based Interactive Landform Simulation Model (WILSIM),” Computers and Geosciences. v. 30, n. 3, p. 215-220.
Luo, W., 2004, “Using a GIS-based Floating Catchment Method to Assess Areas with Shortage of Physicians,” Health and Place, v. 10, n. 1, p. 1-11 Abstract
Luo, W. and F. Wang, 2003, “Measures of Spatial Accessibility to Healthcare in a GIS Environment: Synthesis and a Case Study in Chicago Region,” Environment and Planning B: Planning and Design 2003, v. 30, n .6, p. 865 – 884 Abstract
Luo, W. and J.M. Harlin, 2003, “A Theoretical Travel Time based on Watershed Hypsometry,” Journal of American Water Resources Association, v.39, n.4., p. 785-792 Abstract
Luo, W. and Wang, F., 2003, Spatial Accessibility to Primary Care and Physician Shortage Area Designation: A Case Study in Illinois with GIS Approaches, in Geographic Information Systems & Health Applications, edited by R. Skinner and O. Khan., Idea Group Publishing, Hershey, PA, pp 260-278 Abstract
Luo, W., 2002, Hypsometric Analysis of Margaritifer Sinus and Origin of Valley Networks, Journal of Geophysical Research - Planets, doi:10.1029/2001JE001500 Abstract
Luo, W., 2001, LANDSAP: a coupled surface and subsurface cellular automata model for landform simulation, Computers and Geosciences, v.27, n.3, 363-367.
Luo W., Hartmann, J. F., Li, J., and Sysamouth V., 2000, GIS Mapping and Analysis of Tai Linguistic and Settlement Pattern of Southern China, Geographic Information Sciences, 6(2):129-136 Abstract
Luo, W., 2000, Quantifying groundwater sapping processes with a hypsometric analysis technique, Journal of Geophysical Research - Planets, v. 105, p. 1685-1694 Abstract
Harlin, J. and Luo, W., 2000, Predicting time to hydrograph peak from basin energy potential: A hypsometric approach, papers and proceedings of the applied geography conferences, v.23: p. 224-229
Wang, F. and W. Luo, 2005, “Assessing Spatial and Nonspatial Factors for Healthcare Access in Illinois: Towards an Integrated Approach to Defining Health Professional Shortage Areas,” Health and Place, v. 11, n. 2, p. 131-146
Abstract: This research
considers both spatial and nonspatial factors in examining accessibility to
primary healthcare in Illinois. Spatial access emphasizes the importance of
geographic barrier between consumer and provider, and nonspatial factors include
non-geographic barriers or facilitators such as age, sex, ethnicity, income,
social class, education and language ability. The population and socioeconomic
data are from the 2000 Census, and the primary care physician data for the
same year are provided by the American Medical Association. First, a two-step
floating catchment area method implemented in Geographic Information Systems
(GIS) is used to measure spatial accessibility based on travel time. Secondly,
the factor analysis method is used to group various socio-demographic variables
into three factors: (1) socioeconomic disadvantages, (2) socio-cultural barriers
and (3) high healthcare needs. Finally, spatial and nonspatial factors are
integrated to identify areas with poor access to primary healthcare. The research
is intended to develop an integrated approach for defining Health Professional
Shortage Areas (HPSA) that may help the U.S. Department of Health and Human
Services (DHHS) and state health departments improve HPSA designation.
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Luo, W., F. Wang, and C. Douglass, 2004, “Temporal Changes of Access to Primary Health Care in Illinois (1990-2000) and Policy Implications,” Journal of Medical Systems. v. 28, n. 3, p. 287-299.
Abstract: This paper
examines temporal changes of access to primary health care in Illinois between
1990 and 2000 in a Geographic Information System (GIS) environment. Census
data at the census tract level in 1990 and 2000 were used to define the population
(demand) distribution and related socioeconomic attributes, and the Physician
Masterfile of American Medical Association in corresponding years was used
to define the physician (supply) distribution at the zip code level. A two-step
floating catchment method was employed to measure the spatial access, considering
locations of physicians and population and travel times between them. Various
socioeconomic and demographic variables were consolidated into three factors
(i.e., socioeconomic disadvantages, socio-cultural barriers and high healthcare
needs) for measuring the nonspatial access. Spatial and nonspatial factors
were finally integrated together to assess the primary care physician shortage
areas. The study shows that spatial accessibility to primary care physician
for the majority of the state improved from 1990 to 2000. Areas with worsened
spatial accessibility were primarily concentrated in rural areas and some
limited pockets in urban areas. The worst among these worsened areas appeared
to be associated with populations with high scores of socio-economically disadvantages,
socio-cultural barriers and healthcare needs. Improving the accessibility
of those socio-economically disadvantaged population groups is critical for
the success of future policies.
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Luo, W., 2004, “Using a GIS-based Floating Catchment Method to Assess Areas with Shortage of Physicians,” Health and Place, v. 10, n. 1, p. 1-11
Abstract: This paper
presents a Geographic Information System (GIS) based floating catchment method
for identifying physician shortage areas. The traditional designation methods
are primarily regional availability measures, which use administrative boundaries
such as counties as the basic spatial units for calculating physician to population
ratios and designate shortage based on those ratios. Such approaches have
been criticized for their inability to account for either the spatial variations
of population demand and physician supply within those boundaries or for population-physician
interactions across them. The floating catchment method addresses the internal
spatial distribution problem by deriving population data from a smaller unit,
the census tract. The potential cross border patient-physician interaction
is taken into consideration by using circles of reasonable radius around each
census tract centroid as the basic spatial units, which can encompass areas
on either side of an administrative border. By varying the radius of the catchment
circle, this paper demonstrates that the physician to population ratio is
scale dependent and that the greatest variability of the ratios and shortages
occur at the most local scales (< 20 miles), which argues for using finer
spatial resolution data in shortage designation practice.
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Abstract: This research
considers both spatial and nonspatial factors in examining accessibility to
primary healthcare in Illinois. Spatial access emphasizes the importance of
geographic barrier between consumer and provider, and nonspatial factors include
non-geographic barriers or facilitators such as age, sex, ethnicity, income,
social class, education and language ability. The population and socioeconomic
data are from the 2000 Census, and the primary care physician data for the
same year are provided by the American Medical Association. First, a two-step
floating catchment area method implemented in Geographic Information Systems
(GIS) is used to measure spatial accessibility based on travel time. Secondly,
the factor analysis method is used to group various socio-demographic variables
into three factors: (1) socioeconomic disadvantages, (2) socio-cultural barriers
and (3) high healthcare needs. Finally, spatial and nonspatial factors are
integrated to identify areas with poor access to primary healthcare. The research
is intended to develop an integrated approach for defining Health Professional
Shortage Areas (HPSA) that may help the U.S. Department of Health and Human
Services (DHHS) and state health departments improve HPSA designation.
Top
Luo, W. and J.M. Harlin,
2003, “A Theoretical Travel Time based on Watershed Hypsometry,”
Journal of American Water Resources Association.
Abstract. The time to hydrograph peak of a watershed basin has been found
to correlate with various statistical attributes (e.g., skewness and kurtosis)
of its hypsometric curve (treated as probability distribution). This paper
presents a theoretical travel time that is conceptually analogous to the time
to hydrograph peak and can be calculated directly from the hypsometric curve
of a watershed basin based on gravity and acceleration. The theoretical travel
times for 23 selected watersheds in the United States are found to correlate
significantly with their corresponding hypsometric attributes. In addition,
the theoretical travel times are consistent with the times of concentration
estimated from the FAA method. Thus, this paper offers a simple theoretical
explanation to the empirically identified linkage between time to hydrograph
peak and hypsometric attributes. This theoretical travel time can provide
an alternative way of characterizing the effects of basin morphometry on hydrologic
response.
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Luo, W. and Wang, F.,
2003, Spatial Accessibility to Primary Care and Physician Shortage Area Designation:
A Case Study in Illinois with GIS Approaches, in Geographic Information Systems
& Health Applications, edited by R. Skinner and O. Khan., Idea Group Publishing,
Hershey, PA, pp 260-278.
Abstract. This chapter introduces two new GIS-supported methods of measuring
accessibility to primary healthcare. The improved floating catchment method
defines the service area of physicians by a threshold travel time while accounting
for the availability of physicians. The gravity-based accessibility method
considers two factors: travel times from service providers (a nearby supply
is more accessible than a remote one) and competition intensity by residents
for such a service (measured by gravity-based potential). The methods are
applied to examining accessibility to primary care in northern Illinois region
in 1990 and 2000. The GIS-based methods may be used to help the U.S. Department
of Health and Human Services and state Health Departments define health professional
shortage areas.
Top
Luo, W., 2002, Hypsometric Analysis of Margaritifer Sinus and Origin of Valley Networks, Journal of Geophysical Research - Planets, doi:10.1029/2001JE001500
Abstract. The formation
of Martian valley networks has been debated since their discovery. The relative
roles of groundwater sapping and fluvial runoff processes have different implications
on Martian paleoclimate. This paper uses a hypsometric analysis technique
that has been tested on terrestrial landforms to analyze the hypsometric attributes
of watershed basins in the Margaritifer Sinus region on Mars using Mars Orbiter
Laser
Altimeter (MOLA) gridded topographic data. On the basis of quantitative characteristics
of their hypsometric attributes, the majority of the basins (covering 3/5
of the study area) look more like terrestrial basins of sapping origin, and
a significant number of basins (covering 1/5 of the study area) are more fluvial
like. The classification of the rest of the basin is less certain at the presently
available resolution of the digital elevation model (DEM). Overlay with Viking
photomosaic indicates that the classification is generally consistent with
the morphology shown in Viking images. Although this analysis alone cannot
make a sure determination of valley network origin, combined with other morphometric
analysis, the results from this study are consistent with a valley network
formation by precipitation-recharged groundwater sapping, suggesting a warm
and wet climate for early Mars.
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Luo W., Hartmann, J. F., Li, J., and Sysamouth V., 2000, GIS Mapping and Analysis of Tai Linguistic and Settlement Pattern of Southern China, Geographic Information Sciences, 6(2):129-136.
Abstract: By integrating
linguistic information and physical geographic features in a GIS environment,
this paper maps the spatial variation of terms connected with wet-rice farming
of Tai minority groups in southern China and shows that the primary candidate
of origin for proto-Tai is in the region of Guangxi-Guizhou, not Yunnan or
the middle Yangtze River region as others have proposed. In addition, Tai
speaking people (Zhuang and Bouyei) settle at low elevations along rivers
where they can practice irrigated rice farming, in contrast to the Yi, members
of the Sino-Tibetan language family, who are found at higher elevations. The
patterns of different ethnolinguistic groups exploiting different ecological
niches are likely true for all of Asia. GIS technology has great potential
to help explain such patterns and understand population movements and distributions.
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Luo, W., 2000, Quantifying groundwater sapping processes with a hypsometric analysis technique, Journal of Geophysical Research - Planets, v. 105, p. 1685-1694.
Abstract. The groundwater-sapping
process generates peculiar landform features, including amphitheater channel
head, U-shaped cross section with steep wall and flat floor, and short stubby
tributaries. However, previous attempts to quantify this landform were primarily
limited to the planform geometry of the channel networks and the network topology.
The elevation or relief information, which is more revealing of the processes
that gave rise to the landform, has not received enough attention in the literature.
The hypsometric curve (area-altitude relation) combines area and relief elegantly.
By treating the hypsometric curve as a probability distribution, one can quantitatively
distinguish small differences in the shape of the curve (and thus in the characteristics
of the landform) on the basis of hypsometric integral, the skewness and kurtosis
of the curve, and the skewness and kurtosis of its density function. Preliminary
results of applying this technique within an automated Geographic Information
System (GIS) environment to typical terrestrial sapping landforms show that
they are characterized by high hypsometric integral, low hypsometric skewness,
negative density skewness, and high density kurtosis as compared with typical
fluvial landforms in humid regions. Statistical analyses indicate that the
differences on these hypsometric attributes between typical sapping and typical
terrestrial fluvial landforms are statistically significant. Thus the hypsometric
analysis technique and hypsometric attributes can be used to quantify landforms.
This technique, along with other lines of evidence, can be applied to help
identify the origin of landforms on other planets such as Mars, where groundwater-sapping
is thought to have played an important role in its landform evolution.
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Recent Funded Grants
05/04 - 05/07 Principal Investigator, Comprehensive Morphometric Analysis of Martian Valley Network Basins: Evaluating Relative Role of Groundwater Sapping vs. Surface Runoff, NASA Summary
02/04 - 01/09 Co-PI (with Liping Di at George Mason), Earth Science REASoN - Research, Education and Applications Solutions Network: A Distributed Network of Data and Information Providers for Earth Science Enterprise Science, Applications and Education, NASA Summary
3/02-2/04 Principal Investigator (with Kirk Duffin and Jay Stravers), Web-Based Interactive Simulation of Landform Evolution, National Science Foundation Summary
09/01 - 08/03 Co-Principal Investigator (with Fahui Wang and Carolinda Douglas), Primary Care Physician Shortage & Spatial Accessibility, Agency for Healthcare Research and Quality, Department of Human Health and Services Summary
06/00 - 05/01 Principal
Investigator, "Physician Shortage Area and Health Care Accessibility:
A GIS approach," NIU-Social Science Research Institute, Faculty Fellowship
for 2000-2001
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Recent Funded Grants
05/04 - 05/07 Principal Investigator, Comprehensive Morphometric Analysis of Martian Valley Network Basins: Evaluating Relative Role of Groundwater Sapping vs. Surface Runoff, NASA
Project Summary
There is continued debate about the origin of Martian valley networks. Whether
they are formed predominantly by groundwater sapping or surface fluvial runoff
has profoundly different implications for the climatic history of Mars and
the possible evolution of life there. As different processes generally leave
different morphologic characteristics on the land surface, quantitative morphometric
analysis of the landform may offer important insight into the formation processes.
The purpose of this project is to evaluate the relative role of groundwater
sapping vs. surface runoff in forming Martian valley networks by undertaking
a comprehensive morphometric analysis of Martian watershed basins. Both traditional
morphometric parameters and hypsometric statistical moments will be used to
quantify the basin morphology. Typical terrestrial groundwater sapping and
fluvial landforms and typical lunar cratering landforms will be used as end
members, representing the three most important processes for Martian valley
network landforms. Morphometric parameters of the end member basins will be
extracted and used to establish discriminant functions for classifying Martian
basins. The highest resolution Digital Elevation Models (DEMs) from Mars Orbiter
Laser Altimeter (MOLA) will be used to delineate watershed boundaries and
to extract morphometric parameters. Each Martian basin will then be classified
based on their morphometric parameters using the discriminant functions established
from the parameters of the end members. The effect of later modification by
other processes (such as mass wasting, eolian filling, and volcanic lava flow)
on morphometric parameters will be assessed by inputting the end member landforms
to a physically based computer simulation model where the modification processes
are operating. The posteriori probability that each basin belongs to each
end member class (i.e., fluvial, sapping and cratering) after removing the
modification effect will be computed and used as a quantitative measure of
the relative importance of that process. Spatial variation of the morphometric
parameters with latitude, elevation, and age, and the overlays of classification
results with Viking and Mars Orbiter Camera (MOC) imagery data will be examined
collectively to evaluate past geomorphic processes and climatic conditions.
Top - Grants
02/04 - 01/09 Co-PI (with Liping Di at George Mason), Earth Science REASoN - Research, Education and Applications Solutions Network: A Distributed Network of Data and Information Providers for Earth Science Enterprise Science, Applications and Education, NASA
Dr. Luo will work with the PI and his team at GMU to develop course materials that will involve students in remote sensing and GIS classes to test the data and software developed by the PI’s team; will provide feedback to the PI’s team on the software and data accessibility and suggest ways of improvement.
3/02-2/04 Principal Investigator (with Kirk Duffin and Jay Stravers), Web-Based Interactive Simulation of Landform Evolution, National Science Foundation
Project Summary
Computer simulation is an ideal tool for understanding the complex effects
of a variety of physical and geological processes that interact to influence
landform evolution over extended periods of time (centuries, thousands of
years, millions of years). Yet the simulation models and the visualization
of their results usually require specialized software that is not easily accessible
to undergraduate education. This proof-of-concept project will develop a web-based
interactive landform simulation model that can be accessed anytime and anywhere
via a standard web browser to improve undergraduate students' learning experience
of landform evolution. This web-based interactive model will employ a cellular
automata algorithm and will be implemented using Java technology, which is
designed to run on different computer hardware and operating systems. Students
will be able to interact with the model by selecting and manipulating different
parameters (such as precipitation intensity, degree of surface runoff, rock
erodibility, tectonic movement, etc.) through a Graphical User Interface and
observe how different combinations of processes (parameters) influence the
landform evolution. This project will integrate the latest technology into
undergraduate education to improve both teaching and learning. Because of
its global potential in web based dissemination, it will have the ability
to reach a wide and diverse audience, including underrepresented populations
in Science, Mathematics, Engineering, and Technology, non-traditional students,
and students with learning disabilities. In addition, it will help the investigators
develop professionally in a new exciting area of the 3D visualization on the
web, which will be beneficial to their own respective teaching and research.
Website: http://www.niu.edu/landform
Top - Grants
09/01 - 08/03 Co-Principal
Investigator (with Fahui Wang and Carolinda Douglas), Primary Care Physician
Shortage & Spatial Accessibility, Agency for Healthcare Research and
Quality, Department of Human Health and Services
Project Summary
Current methods for designating physician shortage areas are primarily based
on the ratio of providers to population within a geopolitical boundary (e.g.,
county) and fail to adequately reflect the fact that the availability of services
depends, not only upon the supply of resources in a community, but also the
supply of such resources in neighboring communities and the distance and ease
of travel among them. Taking advantage of the physicians and demographic data
at fine geographic scales and recent development in the literature of accessibility
measures, this research will use two new GIS-based methods to improve the
identification of physician shortage areas. Specifically, improvements are
made by: (1) mapping the location of physicians more precisely, (2) using
a smaller areal unit for population distribution (i.e., census tract), (3)
considering the physician-patient interaction across areal units, and (4)
accounting for the road network travel time between patients and physicians.
This project will (1) compare the physician shortage areas defined by the
new methods with current systems, identify discrepancies, and evaluate improvements
made by the new methods; (2) examine whether the shortage areas coincide with
the distribution of disadvantaged population groups (minority and low-income
residents) and make relevant policy recommendations; and (3) analyze the change
of health care access between 1990 and 2000 and evaluate whether and where
the past HPSA and MUA/MUP designations have helped improve health care access
for certain areas.
Top - Grants
Presentations / Poster Sessions
Luo, W., J. Hartmann, P. Huang, J. Liu, “Geographic Patterns of Zhuang [Tai] Kinship Terms in Guangxi and Border Areas: A GIS (Geographical Information Systems) Analysis of Language and Culture Change,” presented at Social Science History Association 29th Annual Meeting, November 18-21, 2004, Chicago.
Luo, W., E. Peronja, K.L. Duffin, J.A. Stravers, “Incorporating Nonlinear Rules in a Web-Based Interactive Landform Simulation Model (WILSIM),” presented at Geological Society of America annual meeting, November 7-10, 2004, Denver, Colorado.
Luo W. Arvidson R. E. Howard A. D., “Hypsometric Analyses of Martian Valley Networks at Watershed Basin Scale,” presented at Second Conference on Early Mars, October 11-15, 2004, Jackson Hole, Wyoming. Poster
Luo, W., “Morphometric Analysis of Martian Valley Networks and Paleoclimatic Implications,” presented at “CHICAGO 2004, A Workshop to Foster Broader Participation in NASA Space Science Missions and Research Programs”, June 28-29, 2004, Chicago.
Luo, W., K.L. Duffin, E. Peronja, J.A. Stravers, G.M. Henry, “Web-based Interactive Landform Simulation Model (WILSIM),” presented at “Invention and Impact: Building Excellence in Undergraduate STEM Education, National Science Foundation (NSF) Course, Curriculum, and Laboratory Improvement (CCLI) program conference”, Crystal City in Arlington, Virginia, April 16-18, 2004. Poster
Luo, W., F. Wang and
C. Douglass, “Temporal Changes of Access to Primary Health Care
in Illinois (1990-2000) and Policy Implications,” presented at
Association of American Geographers Centennial Meeting, Philadelphia, March
14-19, 2004
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