GRAVITY MODEL APPLICATIONS IN HEALTH PLANNING: ANALYSIS OF AN URBAN HOSPITAL MARKET*

ABSTRACT. In this paper a gravity model is formulated to model a hospital patient flow system. Both spatial and nonspatial measures of separation are used to estimate the model. Travel time was found to provide improved fits over linear distance in modeling patient flow behavior. Transformations of travel time (square root and log) were found to improve model performance further. Model diagnostics suggested additional spatial separation measurw, separation measure parameters demonstrated stability over time. The model is used to forecast the effects of health care financing reform and hospital closure on patient flows in an urban hospital market. Universal health coverage was found to dramatically improve access to hospital services for lower income patient populations. Hospitals at risk for closure were forecast to receive increased patient flows. Medical school hospitals are expected to lose patients after implementation of health reform, with important implications for graduate medical education. Hospital closures were shown to have negative effects on access to services in poor neighborhoods, but relatively little effect on access in the system as a whole.     

Modeling Distance Decay Effects in Web Server Information Flows

Previous studies have shown that there is a direct correlation between the popularity of a medium and the cost in transmitting information through that medium. On this basis the World Wide Web may become more important as a mass medium than radio and television. Yet despite the enormous growth in Internet information and Internet-supported businesses, there has been, as yet, little in the way of quantitative spatial analysis of information flows on the WWW. One major issue is whether or not distance influences the web sites that a user may visit. If distance is a factor, then the location of servers delivering content becomes important. In this paper an analysis of information flows from U.K. academic web servers to the rest of the world is carried out. Using a UNIX utility called ping, the average time taken for a defined amount of information to travel between the United Kingdom and sixty-six other countries across the Internet was measured. This time measurement known as latency is used as a measure of distance on the Internet. The latency measurements are combined with counts of visitors from each of these countries to approximately one hundred U. K. academic WWW servers and used to build a simple gravity model of WWW information flows. The latency measurements between the United Kingdom and the other countries were gathered over a week in 1996. The counts of visitors relate to the total number of visits to the web servers over various time-scales for the years 1995 and 1996. We make the assumption that the distance measurements used are relevant to the visit counts. We also assume that all visitors from the .edu domain are geographically located in the United States. The gravity model is used to determine the effect of Internet distance on the number of expected visits to a web server. The study shows that latency values are a useful metric for measuring Internet distance. The results also demonstrate that the number of visitors to a web site falls off with distance on the Internet, as measured by latency values.     

Modeling Geographic Ferrous Scrap Markets: Regional Prices and Interregional Transactions in the United States*

Abstract. The U.S. Regional Ferrous Scrap Model analyzes spatial variations in prices for two grades of ferrous scrap using a logistic model of choice under differentiated products. The model uses a computer‐generated equilibrium framework to solve for prices that support the observed spatial distribution of supply and demand quantities. This paper presents the model's formal structure and its solution algorithm. The model specification is highly disaggregated with 1,212 supply and 240 demand regions. Characteristics of the equilibrium solution are described for prices and interregional flows. Sensitivity of equilibrium values to changes in model parameters is reported.     

Modelling the relationship between tenure and migration in England and Wales

"A rarely utilized source of migration data from the 1981 [U.K.] Census is used to examine the mobility patterns of migrants resident in different [housing] tenures within England and Wales at the regional and county level. A Poisson regression approach is used to compare the effects of distance on migration propensities for those moving into owner-occupied housing, council housing and privately rented housing. The existing literature suggests that migration should be most restricted by distance for council tenants and least restricted for private renters....Local variations in the effects of distance decay on migration for each of the three migrant streams are examined. Both a north-south and a metropolitan non-metropolitan migration divide are clearly evident when migrant flows are disaggregated by tenure at the destination."     

Seismic Hazards and Water Supply Performance

This article describes seismic hazards, including fault rupture, liquefaction, landslides, and site amplification, using Los Angeles as a case study. Water supply simulation results are presented for a 7.8 M_W earthquake on the San Andreas Fault. Severe water losses are shown after 24 h, with nearly 2,700 locations of pipeline damage and a 66% decrease in normal water service. The water supply system was modeled with and without reservoirs that have been removed from service to meet water quality standards. The results show that opening the disconnected reservoirs immediately after a serious earthquake is an effective strategy for emergency response.     

A Visit to Burma

ABSTRACT

Closure of small schools has been a contentious policy issue, addressed most recently in the Schools Consultation (Scotland) Act 2010. Local authorities are currently delivering public service under great financial pressure and, given the high per capita costs of running small schools, have often sought to close them. One of the arguments for retaining small schools is the purported contribution that they make in maintaining rural community vibrancy. However, the evidence base for retaining small schools as ‘the heart of the rural community’ is largely untested, and such evidence as there is suggests that school closures have a modest effect on community vibrancy. School catchment studies show a long-term pattern of adjustment to demographic changes but this process may be curtailed by government policy in Scotland. A solid employment base and affordable housing are deemed by many to be more important factors in rural socio-economic wellbeing than the presence or absence of a primary school.     

Residual rickets or osteomalacia: a case dating from the 16–18th centuries from Krosno Odrzańskie,Poland

A skeleton from a 16–18^th century burial site in Krosno Odrzańskie, Poland, was examined using classical morphological, metric and macroscopic palaeopathological observations, as well as radiography and tomography of the skull and long bones. A wide variety of the observed bone deformations probably occurred as a consequence of past rickets and/or osteomalacia, whose primary cause may also have been chronic renal failure. Preservation of the bones enables a discussion of the cause of such pathological changes. The subject under study appears to be a very interesting example of an individual whose skeleton shows advanced pathological alterations associated with the subject's vitamin D deficiency, overall health conditions and relatively long lifespan. Copyright © 2008 John Wiley & Sons, Ltd.     

Using Discrete Event Simulation Models to Evaluate Resilience of an Emergency Department

Hospitals are critical infrastructures which are vulnerable to natural disasters, such as earthquakes, man-made disasters and mass causalities events. During the emergency, the hospital might also incur in structural and non-structural damage, have limited communication and resources, so they might not be able to treat the large number of incoming patients. For this reason, the majority of medium- and large-size hospitals have an emergency plan that expands their services quickly beyond normal operating conditions to meet an increased demand for medical care, but it is impossible for them to test it before an emergency occurs. The objective of this article is to develop a simplified model that could describe the ability of the Hospital Emergency Department to provide service to all patients after a natural disaster or any other emergency. The waiting time is the main response parameter used to measure hospital resilience to disasters. The analytical model has been built using the following steps. First, a discrete event simulation model of the Emergency Department in a hospital located in Italy is developed taking into account the hospital resources, the emergency rooms, the circulation patterns and the patient codes. The results of the Monte Carlo simulations show that the waiting time for yellow codes, when the emergency plan is applied, are reduced by 96%, while for green codes by 75%. Then, using the results obtained from the simulations, a general metamodel has been developed, which provides the waiting times of patients as function of the seismic input and the number of the available emergency rooms. The proposed metamodel is general and it can be applied to any type of hospital.     

The Use of Expert Judgments in Predicting Interregional Migration Patterns: An Analytic Hierarchy Approach

This paper presents an application of Saaty's analytic hierarchy process to the prediction of interregional migration patterns. This application is an example of how Saaty's method can be used in analyzing geographic problems to synthesize the results of theoretical models with the judgments of experts and policymakers. After discussing the basic theory behind Saaty's method and how expert judgments can be inserted into the Tobler-Dorigo migration model, the results of an application of this model to predict migrations between the nine U.S. census regions for the 1965–70 period are used to illustrate the basic steps in this approach.     

中部农区农户打工距离研究——以河南三个样本村为例

对农户打工距离和区位的研究是认识农民工流动空间规律的基础。通过对河南省三个不同类型样本村的实证研究,发现打工距离整体分散、局部集中,打工人数随距离的变化呈"U"型分布,打工者在打工目的地的分布上具有群聚特征。影响农户打工距离选择的主要因素是年龄、家庭类型、家庭代数、上学人数和关系网络因子。年龄较大者、家庭类型较简单者、家庭代数较多者、上学人数较多者和关系网络较少者,选择在本地打工的概率较大,反之亦然。     

The Local Implications of Major Job Transformations in the City: A Spatial Microsimulation Approach

The changing dynamics of regional and local labor markets during the last decades have led to an increasing labor market segmentation and socioeconomic polarization and to a rise of income inequalities at the regional, urban, and intraurban level. These problems call for effective social and local labor market policies. However, there is also a growing need for methods and techniques capable of efficiently estimating the likely impact of social and economic change at the local level. For example, the common methodologies for estimating the impacts of large firm openings or closures operate at the regional level. The best of these models disaggregate the region to the city (Armstrong 1993; Batey and Madden 1983). This paper demonstrates how spatial microsimulation modeling techniques can be used for local labor market analysis and policy evaluation to assess these impacts (and their multiplier effects) at the local level‐to measure the effects on individuals and their neighborhood services. First, we review these traditional macroscale and mesoscale regional modeling approaches to urban and regional policy analysis and we illustrate their merits and limitations. Then, we examine the potential of spatial microsimulation modeling to create a new framework for the formulation, analysis and evaluation of social and local labor market policies at the individual or household level. Outputs from a local labor market microsimulation model for Leeds are presented. We show how first it is possible to investigate the interdependencies between individual's or households labor market attributes at the microscale and to model their accessibilities to job opportunities in different localities. From this base we show how detailed what‐if microspatial analysis can be performed to estimate the impact of major changes in the local labor market through job losses or gains, including local multiplier effects.     

‘In aid of civil power’: The colonial army in Northern India,c.1919–42

India's tribal northeast continues to be a footnote in national and international historiography. Influenced by James C. Scott's recent characterisation of the non-state hill peoples of Zomia and their deliberate evasion of subject status, this article reappraises the 1826 treaty between the British political agent and Khasi leader U Tirot Sing, and the subsequent Nongkhlaw massacre. It further explores a set of British expectations of the hills as a potential site for missionisation and white colonisation. In this way, it asserts the purchase of Scott's theories, but argues for the further potential of micro-history and the colonial archive to render indigenous histories more visible.     

Excessive rightsizing? The interdependence of public school closures and population shrinkage

Shrinking cities have, by definition, lost population. Rightsizing is a strategic planning approach to mitigate the challenges of population loss by adjusting a municipality's services, amenities, or even footprint to fit a new demographic reality. While studies have documented the unacceptability and ineptitude of municipality-driven rightsizing, public school closures have proliferated and quietly become a noteworthy material manifestation of population change. However, as public schools are widely considered to be a foundational component of community cohesion, identity, and prosperity, it begs the question of whether their closure may accelerate the decline feedback mechanisms already present in many shrinking cities. Our study examines public school closures in Ontario, Canada, from 2011 to 2016 to determine the relationship between municipal population trajectories and size and public school closures, and to explore the prevalence of school closures and the community context in shrinking Ontario municipalities. We find that public school closures occurred disproportionately in shrinking and smaller municipalities. Furthermore, public school closure prevalence is associated with low income, low ethnoracial diversity, and low educational attainment.     

What's a School Worth to a Neighborhood? A Spatial Hedonic Analysis of Property Prices in the Context of Accommodation Reviews in Ontario

Due to a change in capital funding formula, many school boards across the Province of Ontario engaged in Accommodation Reviews to rationalize the supply of school capacity. This process led to numerous school closures and raised important policy questions regarding the economic value of a school in terms of its capitalization into property values and, by extension, how the closure of a school might affect local neighborhoods. To explore these questions, this research uses spatial hedonic methods to estimate the implicit value of accessibility to schools in the City of Hamilton, Ontario. Spatial Durbin model results provide evidence of a significant negative correlation between distance to schools and housing prices in the Canadian context. This suggests that accessibility to schools is capitalized into property values and that the closure of a neighborhood school may result in potentially significant losses of economic value in communities.     

Colonial conquests and the politics of normalization: The case of the Golan Heights and Northern Cyprus

The space of exception has been extensively discussed as a location in which governing technologies are deployed through the suspension and manipulation of the norm. The scholarship on the subject has underscored the ways in which various localities can be encamped, which alludes to the dynamic in which spaces of exception can be shaped through the application of various means of sovereign violence that produces new and unpredictable norms. Building on this literature, the article analyzes the ways in which the exception is intentionally used in order to spatially construct the norm. Two case studies are discussed: Israel's occupation of the Golan Heights and the Turkish occupation of Northern Cyprus. The article's main aim is to show how the state of emergency, which provided the justification for deploying exceptional means—occupation and subsequent colonization—was domesticated. By domestication I mean a situation whereby the state of emergency is not fully negated, but rather rearticulated and redeployed in order to reshape the space and transform it so that it is concomitantly both threatening and normal. I go on to show, however, how despite the processes of spatial normalization the state of exception always resurfaces.     

战后中西人文地理学比较研究

回顾二战以来以美、英为代表的西方和中国人文地理学的发展历程,从学科地位与学科体系、哲学思想及思维方式、研究方法与应用领域等方面将两者作以比较,以期更好地了解、借鉴国外经验,为结合我国实际,构建二十一世纪新型的具有中国特色的人文地理学提供借鉴与参考。     

中国城市群对外服务功能强度与结构分析

城市流描述了城市的基本活动部分,体现了城市的对外服务功能。城市流强度揭示了城市对外联系的强弱,它与城市中心性的极强相关性表明,城市流强度是表征城市对外服务功能的量化指标。通过中国13个主要城市群的城市流强度与结构分析,从城市流视角探讨中国城市群对外服务功能空间分布特征及其增长情况。研究表明,长三角、珠三角城市群是全国性的以制造业为主的综合型对外生产服务中心,京津冀北城市群是全国性的以第三产业为主的综合型对外生产服务中心,山东半岛城市群初步形成以第二产业为主的全国性对外生产服务中心,成渝、辽中南等其余9个城市群为区域性对外生产服务中心。研究指出,城市群往往生成于我国各级产业轴线交汇的地方,由产业轴级别差异,将会形成不同规模等级的城市群,由此可以从各级产业轴线上寻找和培育新的城市群。研究认为,由城市流强度占GDP比重而确定的外部贡献率,是城市的基本活动部门对地区生产总值增长的贡献份额,城市群区域内部密切的经济联系与交流提高了各城市的外部贡献率,由城市间密切经济联系而形成的城市流是城市群演化发育的内在机制之一。     

The United States and Bahrain: Interpreting the Differentiated U.S. Responses to the Arab Spring

We examine how the United States' response to the situation in Bahrain can be differentiated from that in Libya and Egypt based on a comparative content analysis of the U.S. administration's press releases, remarks, and interviews during the first three months of the Arab Spring movement. Our findings indicate that although the level and duration of violence were comparable, the U.S. government response was strikingly different with the support given to the Bahraini government, in contrast to the critical stances adopted towards Libya and Egypt. We explain how the United States' lack of political incentive to act and concerted support by its allies were influential factors for the United States' differentiated policy during the Arab Spring.     

Observations Of Water Hardness From Southwest Devon Island, Northwest Territories

Over the thaw period of 1970, the hardness in “Jason's Creek” increased systematically. Waters from other sources in the area, sampled in 1969 and 1970, show increases in hardness with distance of travel downslope, from large flows to small flows, and from flowing water to standing water. The highest total hardness values are from vegetated pools of standing water (as also reported by Smith (1969) in Somerset Island). The hardness of water which has had no contact with regolith or bedrock can be sharply differentiated from that of water which has been in such contact. This observation, together with the increase in hardness with distance of travel, may be consequent upon a slow attainment of chemical equilibrium in these arctic waters. It may also be possible to draw a distinction between the solutional work done by snowmeit water and that done by rainwater. The latter has a lower initial pH and, for comparable volumes of discharge, generates higher values of hardness. These preliminary conclusions are to be tested in future stages of this project, which in 1971 and 1972 will be concerned with the hydrology of a larger stream, the river Mecham, near Resolute on Cornwallis Island. Monitoring of the solute content of waters throughout the Mecham basin is an important part of the proposed research.