Evaluating and re-demarcating the Hospital Service Areas in Florida

The Hospital Service Areas (HSAs) better portray underlying local patterns of hospitalization than administrative units, and offer a promising analysis unit for studies of healthcare market. The widely used Dartmouth HSAs in the U.S. were solely based on Medicare inpatient records about two decades ago. Our analysis used all discharge records from Florida hospitals in the 2011 Healthcare Cost and Utilization Project (HCUP) dataset from the Agency for Healthcare Research and Quality (AHRQ). We first matched Medicare-paid hospitalization records in 2011 to the Dartmouth HSAs for demonstrating the temporal variation of the Medicare-derived HSAs. We then compared the HSA configurations based on the overall hospitalization records to Medicare-derived HSAs in the same year (2011) for assessing the representativeness of the Medicare-derived HSAs. Results indicate the boundaries of the Medicare-derived HSAs have significantly shifted over two decades and are inadequate in representing the overall population. The Huff model was used to generate more solid HSAs than traditional approaches.     

Delineating Hierarchical Hospital Service Areas in Florida

Hospital service area (HSA) and hospital referral region (HRR), known as a hierarchical HSA system, have been used as analysis units in a growing body of large‐scale studies of healthcare spending, utilization, and outcome in the United States. However, the popular Dartmouth HSAs and HRRs were produced more than two decades ago and are unable to represent contemporary healthcare markets. This research uses a revised Huff Model to delineate two levels of hospital service areas in Florida, resulting in sixty‐four HSAs nested in twenty‐one HRRs. Three elements distinguish our method from existing work. First, a best‐fitting distance‐decay function derived from the actual travel pattern of hospitalization is embedded in the Huff Model to strengthen the model's theoretical foundation in individual spatial behavior. Secondly, the hierarchal central place structure is supported by the differing travel‐friction coefficients for general versus specialized patients; general patients experience a steeper gradient and thus a shorter average travel range that supports delineating more HSAs of smaller area size, and specialized patients exhibit a flatter gradient and thus a longer average travel range that leads to fewer HRRs of large‐sized areas. Finally, the delineation method automated in geographic information systems (GIS) can be easily replicated in other regions to define large‐scale and consistent hierarchical HSA systems.     

Developing a flow-based spatial algorithm to delineate hospital service areas

Hospital service areas (HSAs) capture most of local patient-to-hospital travel flows, and have been accepted as the most basic unit for analyzing local hospital utilization and hospitalization patterns. If a given HSA includes multiple hospitals providing care for its residents, it is complicated to assign responsibility for small-area variation in hospital performance or healthcare costs to specific hospitals without established HSA managers. The goal of this study is to produce HSAs with the fewest number of hospitals within an HSA unit. Only a very limited number of studies are related to the HSA delineation. This study reviews the existing approaches to delineate a broader range of service areas besides HSAs. A spatial algorithm named Travel-to-Hospital Algorithm (TTHA) was developed and implemented using the individual hospital discharge records from the Florida State Inpatient Database for 2011. The final output, named the TTHA-derived HSAs, included 14 more eligible divisions in Florida than the HSAs produced by the traditional approach (92 vs. 78), with the degree of self-containment comparable between the two sets of HSAs. The TTHA provides insight into the patterns of hospital visits and holds great value for the delineation of other types of service and catchment areas.     

Planning hierarchical hospital service areas for maternal care using a network optimization approach: A case study in Hubei,China

Improving maternal health is one of the Sustainable Development Goals. Hospital service areas (HSAs), which contain most hospitalization behaviors at the local scale, are crucial for health care planning. However, little attention has been given to HSAs for maternal care and the hierarchy structure. Considering Hubei, central China, as a case study, this study aims to fill these gaps by developing a method for delineating hierarchical HSAs for maternal care using a network optimization approach. The approach is driven by actual patient flow data and has an explicit objective to maximize the modularity. It also establishes the hierarchical structure of maternal care HSAs, which is fundamental for the planning of hierarchical maternal care and referral systems. In our case study, 45 secondary HSAs and 22 tertiary HSAs are delineated to achieve maximal modularity. The HSAs perform well in terms of indices such as the Localization Index and Market Share Index. Furthermore, there is a complementary relationship between secondary and tertiary hospitals, which suggests the need for referral system planning. This study can provide evidence for the validity of the HSA and the planning of maternal care HSAs in China. It also provides transferable methods for planning hierarchical HSAs in other developing countries.     

An automated method for mapping physical soil and water conservation structures on cultivated land using GIS and remote sensing techniques

An efficient and reliable automated model that can map physical Soil and Water Conservation (SWC) structures on cultivated land was developed using very high spatial resolution imagery obtained from Google Earth and ArcGIS®, ERDAS IMAGINE®, and SDC Morphology Toolbox for MATLAB and statistical techniques. The model was developed using the following procedures: (1) a high-pass spatial filter algorithm was applied to detect linear features, (2) morphological processing was used to remove unwanted linear features, (3) the raster format was vectorized, (4) the vectorized linear features were split per hectare (ha) and each line was then classified according to its compass direction, and (5) the sum of all vector lengths per class of direction per ha was calculated. Finally, the direction class with the greatest length was selected from each ha to predict the physical SWC structures. The model was calibrated and validated on the Ethiopian Highlands. The model correctly mapped 80% of the existing structures. The developed model was then tested at different sites with different topography. The results show that the developed model is feasible for automated mapping of physical SWC structures. Therefore, the model is useful for predicting and mapping physical SWC structures areas across diverse areas.     

A double continuous approach to visualization and analysis of categorical maps

A method to visualize multiple membership maps, called ‘Colour mixture’ (CM) is described and compared with alternative techniques: defuzzification and Pixel mixture. Six landform parameters were used to derive the landform classes using supervised fuzzy k-means classification. The continuous categorical map is derived by GIS calculations with colours, where colour values are considered to represent the taxonomic space spanned by the attribute variables. Coordinates of the nine class centres (landform facets) were first transformed from multivariate to two-dimensional attribute space using factor analysis, and then projected on the Hue Saturation Intensity (HSI) colourwheel. The taxonomic value was coded with the Hue and confusion with Saturation. To improve visual impression, saturation was replaced with whiteness. Classes that were closer in attribute space were merged into similar generic colours. The CM technique limits the derived mixed-colour map to seven generic hues independently of the total number of classes, which provides a basis for automated generalization. The confusion index derived from the mixed-colour map was used to derive primary boundaries and to locate areas of higher taxonomic confusion.     

Automatic extraction of building statistics from digital orthophotos

In this paper we discuss uses of image segmentation, feature extraction and Bayesian networks for identifying buildings in digital orthophotos and the utilisation of the results for the automated computation of building statistics. Our work differs from previous attempts in a number of ways. Firstly, image segmentation is accomplished using an adaptive multi-scale method which brings together region and edge information to segment the image into regions. Secondly, automated building feature extraction (e.g. corners) is optimised to fit with expert human annotation performance. The third aspect of this work is the exploration of Bayesian networks as a method for fusing available information (ranging from corner information to solar angles as indicators of shadow location) to classify segmented regions as corresponding to buildings or not. Such processes then permit the automatic compilation of building statistics.     

Magnetic anisotropy produced by magma flow: theoretical model and experimental data from Ferrar dolerite sills (Antarctica)

Volcanic rocks forming sills, dykes or lava flows may display a magnetic anisotropy derived from the viscous flow during their emplacement. We model a sill as a steady-state flow of a Bingham fluid, driven by a pressure gradient in a horizontal conduit. The magma velocity as a function of depth is calculated from the motion and constitutive equations. Vorticity and strain rate are determined for a reference system moving with the fluid. The angular velocity and the orientation of an ellipsoidal magnetic grain immersed in the fluid are calculated as functions of time or strain. Magnetic susceptibility is then calculated for a large number of grains with a uniform distribution of initial orientations. It is shown that the magnetic lineation oscillates in the vertical plane through the magma flow direction, and that the magnetic foliation plane changes periodically from horizontal to vertical. The results are compared with the magnetic fabric of Ferrar dolerite sills (Victoria Land, East Antarctica) derived from low-field susceptibility measurements.     

Geophysical model of the dynamical flattening of the Earth in agreement with the precession constant

The dynamical flattening of the Earth, as observed by geodetic techniques, is different by about 1 per cent from the value associated with the PREM density profile with hydrostatic equilibrium. In this paper, we compute a new dynamical flattening H induced by PREM mean density with hydrostatic equilibrium, to which we add lateral heterogeneities associated with (1) seismic velocity variations observed by tomography and (2) internal boundary topographies. First, we compute mantle circulation associated with the density anomalies derived from a tomography model. The flow-induced boundary deformations are then converted into additional mass anomalies which are added to the tomography model for computing the associated perturbation to the Earth's inertia tensor. Finally, we show that it is possible to obtain a dynamical flattening from the total inertia tensor (i.e. the sum of the PREM inertia tensor and of the perturbation) in agreement with that observed.     

MONITORING GEOMORPHOLOGICAL DISTURBANCE AND RECOVERY IN COMMERCIALLY LOGGED TROPICAL FOREST, SABAH, EAST MALAYSIA, AND IMPLICATIONS FOR MANAGEMENT

Resource development in the form of cyclical commercial logging activities results in a short period of often severe land disturbance followed by a prolonged phase of recovery. The monitoring of catchment sediment yield gives some indication of the gross erosion processes within the catchment as a result of the disturbance and may also effectively measure any ameliorative processes. Studies in Ulu Segama, Sabah, East Malaysia, recorded significant increases in stream suspended sediment loads as a result of logging. Stream loads were derived from a combination of daily sample measurements and storm event sampling using automated liquid samplers. Measured loads were then compared to computed loads from sediment discharge rating sets derived from the actual samples. Application of these ratings in the disturbed catchment initially underestimated sediment loads; however, a progressive overestimation of loads occurred as the catchment vegetation recovered. When using sediment rating curves as a tool to measure catchment erosion rates in disturbed environments, considerable caution has to be used. Vegetation recovery is reflected in the rapid recovery of stream water quality, making it necessary to continually review the rating.     

Ocean-bottom seismograph observations on the Mid-Atlantic Ridge near 45° N

Summary. Rayleigh-wave phase velocities at very long periods (185–290 s) are investigated and regionalized, taking into account the lateral heterogeneities within ocean plates revealed by earlier studies at shorter periods. The two-station method is applied to a few 'pure-age' oceanic paths, and is shown to be compatible with the average Earth model C2 (Anderson & Hart 1976) below depths of 180 km. Under this assumed oceanic model, regionalized for age above 180 km, continental velocities are then derived from a set of experimental great-circle values, both new or taken from previously published studies. The results basically agree with earlier studies (Dziewonski 1970; Kanamori 1970), although they exhibit less scatter than Kanamori's model. Results are successfully checked against a set of values derived by the two-station method from a pure continental path.
Although the shield velocities are substantially different from the mean oceanic ones, they still fall within the range of variation of oceanic velocities with the age of the plate. This makes velocities derived theoretically from Jordan's (1975a, b) models of deep continent—ocean lateral heterogeneities, inconsistent with the present set of experimental data. Finally, we show that Dziewonski's (1971) model S2 reconciles all experimental seismic data relative to shields, without being significantly different from oceanic models below 240 km.     

Inverted Two-Step Floating Catchment Area Method for Measuring Facility Crowdedness

The popular two-step floating catchment area (2SFCA) method has been widely used in the literature to measure spatial accessibility of residents for a service. The 2SFCA method accounts for the ratio between the supply capacity and demand amount of the service as well as the complex spatial interaction between them. This article introduces an inverted two-step floating catchment area (i2SFCA) method that is derived from an extension of the classic Huff model and used to capture the “crowdedness” (scarcity of resource or intensity of competition) for facilities. The method is illustrated and validated by a case study of evaluating hospital inpatient services in Florida. Several possible uses of the measure are also discussed.     

Force-directed layout of origin-destination flow maps

This paper introduces a force-directed layout method for creating origin-destination flow maps. Design principles derived from manual cartography and automated graph drawing to increase readability of flow maps and graph layouts are taken into account. The origin-destination flow maps produced with our algorithm show flows with quadratic Bézier curves that reduce flow-on-flow and flow-on-node overlaps, and avoid sharp or irregular bends in flow lines. A survey of expert cartographers found that flow maps created with our automated method are similar in quality to manually produced flow maps.     

遥感蒸散模型的时间重建方法研究

本文提出的遥感蒸散模型的时间重建方法考虑了逐日蒸散可能的变化情况, 在阻抗- 彭曼单层模型的基础 上, 将图像去云处理与时间重建结合在一起, 先使用SEBS 能量平衡余项模型获得晴好日的地表阻抗信息, 选择了 叶面积指数LAI 作为反映植被表面阻抗的参量, 通过时间序列谐波分析(HANTS)获得逐日逐像元的LAI 信息, 将晴 好日的阻抗信息扩展至待定日, 并使用因子函数表达了极端温湿条件对植被叶面阻抗的限制作用。使用中科院禹 城站2003 年作物季的大型蒸渗仪数据对模型所得逐日蒸散结果进行了验证。在作物生长季, 模型结果相对于实测 结果表现出了良好的相关性(R2≈0.7), 远优于作为对比的蒸发比不变法。受单层模型假设局限, 方法在裸地及稀疏 植被上的结果还存在着较大的误差。     

Multicriteria generalization (MCG): a decision-making framework for formalizing multiscale environmental data reduction

Environmental simulation models need automated geographic data reduction methods to optimize the use of high-resolution data in complex environmental models. Advanced map generalization methods have been developed for multiscale geographic data representation. In the case of map generalization, positional, geometric and topological constraints are focused on to improve map legibility and communication of geographic semantics. In the context of environmental modelling, in addition to the spatial criteria, domain criteria and constraints also need to be considered. Currently, due to the absence of domain-specific generalization methods, modellers resort to ad hoc methods of manual digitization or use cartographic methods available in off-the-shelf software. Such manual methods are not feasible solutions when large data sets are to be processed, thus limiting modellers to the single-scale representations. Automated map generalization methods can rarely be used with confidence because simplified data sets may violate domain semantics and may also result in suboptimal model performance. For best modelling results, it is necessary to prioritize domain criteria and constraints during data generalization. Modellers should also be able to automate the generalization techniques and explore the trade-off between model efficiency and model simulation quality for alternative versions of input geographic data at different geographic scales. Based on our long-term research with experts in the analytic element method of groundwater modelling, we developed the multicriteria generalization (MCG) framework as a constraint-based approach to automated geographic data reduction. The MCG framework is based on the spatial multicriteria decision-making paradigm since multiscale data modelling is too complex to be fully automated and should be driven by modellers at each stage. Apart from a detailed discussion of the theoretical aspects of the MCG framework, we discuss two groundwater data modelling experiments that demonstrate how MCG is not just a framework for automated data reduction, but an approach for systematically exploring model performance at multiple geographic scales. Experimental results clearly indicate the benefits of MCG-based data reduction and encourage us to continue expanding the scope of and implement MCG for multiple application domains.     

Γ型地貌瞬时单位线探讨

在地貌瞬时单位线中作者假定沿任一“路径”的等待时间密度函数成Γ型分布。本文讨论了Γ型地貌瞬时单位线的推导、参数确定和特点。并取蛇家口、三川口流域的突测资料验证,计算洪峰值和涨洪历时与实测值十分接近。     

Γ型地貌瞬时单位线探讨

在地貌瞬时单位线中作者假定沿任一“路径”的等待时间密度函数成Γ型分布。本文讨论了Γ型地貌瞬时单位线的推导、参数确定和特点。并取蛇家口、三川口流域的突测资料验证,计算洪峰值和涨洪历时与实测值十分接近。     

Urbanization of the United States over two centuries: an approach based on a long-term database (1790–2010)

This paper presents an original methodology for the construction of a harmonized database for urban areas in the United States from 1790 to 2010 (a period with a census every 10 years, amounting to 23 dates). Upstream, this method is based on a theoretical choice, the use of a spatio-temporal reference frame to construct urban areas over the long term, defined by a maximum range of one hour’s travel for each period. We used an automatic aggregation from a Reilly model. Urban measures (growth, concentration) derived from this harmonized database are then presented, providing a unified picture of urbanization in the United States over more than two centuries. They are compared with results derived from more classical databases established using the official figures from the Census Bureau, or from other constructions differing from the present system. The results diverge considerably in some instances, which confirms the impact of the method of delineation of geographical areas in measures of growth.     

Improving the representation of major landforms in analytical relief shading

Relief shading is the most common type of cartographic relief representation for print and digital maps. Manual relief shading results in informative and visually pleasing representations of terrain, but it is time consuming and expensive to produce. Current analytical relief shading can be created quickly, but the resulting maps are not as aesthetically appealing and do not show landscape features in an explicit manner. This article introduces an automated digital method that produces shaded relief with locally adjusted illumination directions to simulate the techniques and cartographic principles of manual relief shading. Ridgelines and valley lines are derived from a digital terrain model, vectorized, and used in a diffusion curve algorithm. A graph analysis generalizes the lines before using them for diffusion curve shading. The direction of illumination is adjusted based on the spatial orientation of ridgelines and valley lines. The diffusion curve shading is combined with standard analytical relief shading to create a final diffusion relief shading image. Similar to manual relief shading, major landforms and the structure of the terrain are more clearly shown in the diffusion relief shading. The presented method best highlights major landforms in terrain characterized by sharp, clearly defined ridges and valleys.