bluuebunny/crossref_metadata_2025 huggingface dataset:
Making Tradeoffs for Agroecosystem Health
Authors: Forsyth Margaret , VanLeeuwen John
Published: September 2010

ABSTRACT

Existing definitions of agroecosystem health do not address one of the most important issues, namely, how tradeoffs should be made among different components of an agroecosystem. To resolve this issue, it is important to be clear on which perspective is being taken in any health assessment. An internal perspective would focus on the health of the biophysical components of the agroecosystem, whereas an external perspective would focus on human communities. This article proposes a three‐stage, transdisciplinary approach to agroecosystem health, called a Framework for Agroecosystem Health Tradeoffs, which uses internal and external perspectives at different stages. In the first stage, the type of ecosystem and the time and spatial scale of concern are identified. Once this is established, required levels of biophysical indicators are set and monitored to ensure that basic internal needs for agroecosystem survival are met. In determining levels of biophysical indicators, “positivistic” scientific analysis would be required as well as normative judgments by society on acceptable levels of risk. The third stage involves determining the potential for making tradeoffs in the agroecosystem that would be beneficial to society without affecting the required levels of biophysical indicators specified in the second stage. Economic analysis and community consultation would be used to determine which agroecosystem components or services are valued most by society so that decisions on tradeoffs could be made. Although there remain practical problems in implementing this approach, the notion of setting minimum constraints which human activity cannot violate and making the best tradeoffs possible after these constraints are met provides a useful framework to begin putting agroecosystem health into practice.
Is Economic Development Compatible with Ecosystem Health?
Authors: Rapport D.J.
Published: September 2010

ABSTRACT

The incessant quest for economic growth has dominated human energies for centuries. However, the costs in terms of social and ecological disruption have seldom been taken into account. In consequence, the Earth’s ecosystems have been increasingly disabled. The root problem lies in archaic economic thinking that is completely divorced from natural process. This thinking entrains the notions of unlimited substitution for scarce resources, growth without limits, and the myth that nature’s services are in never‐ending supply. If there is to be a viable future for humankind, this thinking must give way to the realization that the economic process has steadily undermined one of the most critical societal goals, namely, that of preserving the health and integrity of the earth’s ecosystems. If we are to find our way, economic development must be tempered by ecological and social realities.
Electrographic Aspects of “Epileptic” Neuronal Aggregates
Authors: MARSAN C. AJMONE
Published: September 2010

Court exposé des principaux traits morphologiques caractéristiques de I'activité électrique des agglomérations neuronales épieptiques (ANE) tel qu'on les enregistre au moyen de macro‐ et microélectrodes. L'auteur étudie quelques phénomtnes neurophysiologiques fondamentaux par la comparaison du rǒle qu'ils jouent dans le comportement des agglomérations neurales normales et dans celui des ANE; il reléve les caractères différentiels qui se montrent les plus semblables dans les deux situations. Il analyse et discute les mécanismes fondamentaux susceptibles dlětre impliqués dans la génération et le maintien d'une activité épileptiforme. On distingue deux aspects dans I'activité des ANE: inter‐ictale et ictale. L'analyse des procès responsables d'un “firing” (interictal) cyclique paroxysmal et de I'activité organisée, répétitive, autosoutenue (ictale) dans l'ANE, ainsi que celle du passage de l'un à l'autre, éveille la pensée que, outre de simples différences quantitatives, autre chose encore caractérise ces deux types d'activité. L'auteur suggère que, tandis que le premier phénomène peut, théoriquement, se produire dans le neurone isolé, le second ne peut se présenter que dans l'ANE. La signification des éléments nerveux spécifiques et/ou le rǒle de certaines parties de la cellule en un ANE donné est considérée comme de moindre importance.
Triggering Mechanisms in Epilepsy The Electroclinical Point of View
Authors: GASTAUT H. , TASSINARI C. A.
Published: September 2010

Les auteurs distinguent trois variétés de crises épileptiques suivant leurs conditions d'apparition:

A. Les crises épileptiques fortuites

B. Les crises épileptiques cycliques

1. avec une périodicité latente;

2. avec une distribution cyclique manifeste liée au cycle nyctohémérique ou à des facteurs hormonaux (cycle oestral, puberté, ménopause).

C. Les crises épileptiques provoquées

Crises provoquées par des facteurs déclenchants non‐sensoriels:

(a) hyperthermie, (b) ingestion d'alcool, (c) hyperpnée, (d) désordres métaboliques, (e) fatique physique et privation de sommeil, (f) émotions, (g) lecture (variété intrinsèque ou perceptive de l'épilepsie de la lecture), (h) audition (épilepsie musicogénique), (i) exploration visuelle (variété intrinsèque ou perceptive de l'épilepsie par exploration visuelle).

Crises provoquées par des facteurs déclenchants sensoriels ou épilepsie réflexe stricto‐sensu:

(a) crises provoquées par des stimuli visuels:

(i) crises provoquées par la lumière intermittente (y compris l'épilepsie de la télévision)

(ii) crises provoquées par la lecture et l'exploration visuelle (variété extrinsèque ou sensorielle de l'épilepsie de la lecture et de l'exploration visuelle)

(iii) crises provoquées par la fermeture des yeux.

(b) crises provoquées par des stimuli sensoriels végétatifs.

(c) crises provoquées par des stimulations sensorielles inopinées entraînant une réaction de surprise (épilepsie sursaut):

(i) épilepsie‐sursaut provoquée par des stimulations auditives

(ii) épilepsie‐sursaut provoquée par des stimulations extéroceptives ou proprioceptives (y compris l'épilepsie du mouvement).

Crises volontairement provoquées par le sujet lui‐même (épilepsie auto‐provoquée).

Crises provoquées par des stimuli conditionnels.

Dans leurs conclusions les auteurs proposent l'hypothèse de travail suivante: chez l'homme, les facteurs qui transforment un foyer au repos (cortical ou “centrencéphalique) en foyer générateur d'une activité épileptique propagée, n'agissent pas par l'intermédiaire d'un mécanisme réflexe spécifique, mais agissent sur l'ensemble du cerveau, soit directement, soit indirectement par l'intermédiaire des structures souscorticales à projections diffuses.
Review: Health Care Decision‐Making WebCT Module for Medical Students
Authors: Howe Carol L.
Published: September 2010

The Health Care Decision‐Making Module was initially created as an interactive WebCT program and was subsequently converted to a pdf format for posting on the Portal of Geriatric Online Education in early 2006 and updated on October 29, 2009. WebCT was the first of what are now many comprehensive software programs used by universities for conducting online courses. The current Health Care Decision‐Making module is a straightforward pdf with embedded hyperlinks and exercises, allowing for easy downloading, sharing, and adapting by other institutions.
Sexual Aggression Between Residents in Nursing Homes: Literature Synthesis of an Underrecognized Problem
Authors: Rosen Tony , Lachs Mark S. , Pillemer Karl
Published: September 2010

Evidence exists suggesting that most sexual aggression against older adults occurs in long‐term care facilities. Fellow residents are the most common perpetrators, often demonstrating inappropriate hypersexual behavior caused by dementing illness. This resident‐to‐resident sexual aggression (RRSA) is defined as sexual interactions between long‐term care residents that, in a community setting, at least one of the recipients would be likely to construe as unwelcome and that have high potential to cause physical or psychological distress in one or both of the involved residents. Although RRSA may be common, and physical and psychological consequences for victims may be significant, this phenomenon has received little direct attention from researchers. This is a review of the existing literature and relevant related research examining elder sexual abuse and hypersexual behavior that describes the epidemiological features of this phenomenon, including risk factors for perpetrators and victims. The legitimate and recognized need for nursing home residents, even those with advanced dementing illness, to express themselves sexually makes preventing and managing sexual aggression in nursing homes more challenging. This review discusses the ethical dilemma this situation creates and the need to evaluate the capacity to consent to sexual activity of residents with dementing illness and to re‐evaluate capacity as the diseases progress. Suggestions are offered for managing incidents of RRSA and for future research, including the importance of designing effective interventions.
Medical Student Perspectives on Geriatrics and Geriatric Education
Authors: Bagri Anita S. , Tiberius Richard
Published: September 2010

OBJECTIVE: To ascertain medical students' perspectives on geriatrics.

DESIGN: Interpretative phenomenological analysis.

SETTING: An allopathic, Liaison Committee on Medical Education–accredited, former Donald W. Reynolds Foundation grant recipient, U.S. medical school.

PARTICIPANTS: Thirty fourth‐year medical students who completed geriatric educational activities in all 4 years of medical school.

MEASUREMENTS: Two researchers independently reviewed verbatim transcripts from five focus groups and identified themes using the constant comparative method.

RESULTS: Seventeen themes that elaborate on students' perspectives on geriatrics were identified. Students reported not feeling appropriately engaged in geriatrics, despaired at the futility of care, were depressed by the decline and death of their patients, were frustrated by low reimbursement rates and low prestige despite fellowship training, were concerned about patients' unrealistic expectations and opportunities for litigation, felt unsure how to handle ethical dilemmas, and found communicating with older adults to be enjoyable but time consuming and challenging. They felt they had too much exposure to geriatrics in medical school.

CONCLUSION: Current attitude scales fail to capture some of the dimensions uncovered in this study, whereas students did not mention other dimensions commonly included in attitude scales. Regarding curriculum development, students may find an integrated preclinical geriatric curriculum to be more relevant to their careers than a stand‐alone curriculum. Clinical clerkships might be in a better position to emphasize the positive aspects of geriatrics and develop strategies to address students' negative attitudes.
Psychiatric Comorbidity in Children with Epilepsy … or is It: Epilepsy Comorbidity in Children with Psychiatric Disorders?
Authors: Kanner Andres M.
Published: September 2010

Psychiatric Comorbidity in Children with New Onset Epilepsy. Jones JE, Watson R, Sheth R, Caplan R, Koehn M, Seidenberg M, Hermann B. Dev Med Child Neurol 2007;49(7):493–497. The aim of this study was to characterize the distribution, timing, and risk factors for psychiatric comorbidity in children with recent onset epilepsy. Children aged 8 to 18 years with recent onset epilepsy (<1 year in duration) of idiopathic etiology ( n = 53) and a healthy comparison group ( n = 50) underwent a structured psychiatric diagnostic interview to characterize the spectrum of lifetime-to-date history of comorbid psychiatric disorder. There was no significant difference between the children with recent onset epilepsy and healthy comparison children in sex (31 males, 22 females vs 23 males, 27 females) or mean age 12.7y [SD 3.3] vs 12.7y [SD 3.2]). Children with recent onset epilepsy exhibited an elevated rate of lifetime-to-date Diagnostic and Statistical Manual of Mental Disorders, 4th edition (DSM-IV) Axis I disorders compared with the comparison group. They showed significantly higher rates of depressive disorders (22.6 vs. 4%, p = 0.01), anxiety disorders (35.8 vs 22%, p<0.05), and attention-deficit-hyperactivity disorder (26.4 vs 10%, p = 0.01) with elevated but less prevalent rates of oppositional defiant and tic disorders. A subset of children with epilepsy (45%) exhibited DSM-IV Axis I disorders before the first recognized seizure, suggesting the potential influence of antecedent neurobiological factors that remain to be identified. The increased prevalence of psychiatric comorbidity antedating epilepsy onset may be consistent with the presence of underlying neurobiological influences independent of seizures, epilepsy syndrome, and medication treatment.
Relevance of Basic Research to Clinical Data: Good Answers, Wrong Questions!
Authors: Ben-Ari Yehezkel , Holmes Gregory L.
Published: September 2010

Do early seizures beget seizures later in life? Clinical data and experimental observations seem to answer that question differently, with a no and a yes, respectively, which may stem from an inadequate readout of what experimental data actually do tell us and a possible simplification of what clinical data indicate. Using specific experimental examples, it is possible to show that in the developing brain, seizures do produce long-lasting alterations of neuronal excitability, although ongoing seizures are not observed in adults. The findings suggest that the long-lasting changes in developmental programs and network activity that seizures induce do not necessarily lead to epilepsy, unless other events that remain to be identified occur.
Contribution of attitudinal factors to blood donation in African American church attendees
Authors: James Adelbert B. , Demmons Derrick G. , Schreiber George B. , Hillyer Christopher D. , Shaz Beth H.
Published: September 2010

BACKGROUND: Historically, African Americans have a general mistrust for the health care system that has contributed to significant health disparities. The goal of this study was to evaluate whether this distrust among African Americans affects attitudes toward blood donation.

STUDY DESIGN AND METHODS: Fifteen African American churches in metropolitan Atlanta participated in an 81‐item self‐administered survey. The questionnaire assessed barriers and motivators for, and knowledge and beliefs about, blood donation in African Americans. Bivariate analysis and logistic regression models were performed.

RESULTS: A total of 930 individuals responded to the survey. This group was 99% African Americans, 71% female, and 84% college educated, 54% with a household income of at least $50,000 and mean age of 47 ± 14 years. Donation history was 3% current donors, 46% lapsed donors, and 40% nondonors. Respondents who trusted versus distrusted hospitals had more knowledge of the blood supply and less fear of donation and were more likely to respond to blood needs of the community. In a multivariate logistic regression model, donors were more likely to trust hospitals (p = 0.003) and were more likely to have participated in research (p < 0.001) than nondonors.

CONCLUSION: African American distrust of the health care system is associated with decreased likelihood of previous blood donation. This may be secondary to donor centers being viewed as a component of the health care system. Building trust between donor centers and African American community by ensuring the safety of donation may increase African American blood donation rates.
Restaurant Prices and the Minimum Wage
Authors: FOUGÈRE DENIS , GAUTIER ERWAN , LE BIHAN HERVÉ
Published: September 2010

In this paper, we examine the effect of the minimum wage on restaurant prices. We contribute both to the study of economic impact of the minimum wage and to the study of microeconomic patterns of price stickiness. For this purpose, we use a unique data set of individual price quotes collected to calculate the Consumer Price Index in France and we estimate a price rigidity model based on a flexible  rule. We find a positive and significant impact of the minimum wage on prices. The effect of the minimum wage on prices is, however, very protracted. A change in the minimum wage takes more than a year to fully pass through to retail prices.
Monetary Shocks in a Model with Skill Loss
Authors: ESTEBAN‐PRETEL JULEN , FARAGLIA ELISA
Published: September 2010

Unemployment shows persistent and long‐lasting responses to nominal and real shocks. Standard real business cycle models with search frictions but a homogeneous labor force are able to generate some volatility and persistence, but not enough to match the empirical evidence. Moreover, empirical studies emphasize the importance of the heterogeneity of the unemployment pool to fully understand unemployment dynamics. In particular, in most European countries the incidence of long‐term unemployment is large and well known. One of the possible causes/consequences of long‐term unemployment is the skill deterioration of the unemployment pool. In this paper, we introduce the skill loss mechanism, and therefore a heterogeneous labor force, in a New Keynesian framework with search frictions. Calibrating the model for the Spanish economy, we show that while the skill loss mechanism helps to explain the magnitude of the response of unemployment to monetary shocks, it does not improve the performance of the homogeneous worker model in terms of the persistence of the response, especially for short‐ and long‐term unemployment.
Bank Branch Presence and Access to Credit in Low‐ to Moderate‐Income Neighborhoods
Authors: ERGUNGOR OZGUR EMRE
Published: September 2010

Banks specialize in lending to informationally opaque borrowers by collecting soft information about them. Some researchers claim that this process requires a physical presence in the market to lower information collection costs. This paper provides evidence in support of this argument in the mortgage market for low‐income borrowers whose access to credit is limited by their inadequate credit histories. Mortgage originations increase and interest spreads decline when there is a bank branch located in a low‐ to moderate‐income neighborhood.
The Community Reinvestment Act and Targeted Mortgage Lending
Authors: DAHL DREW , EVANOFF DOUGLAS D. , SPIVEY MICHAEL F.
Published: September 2010

We analyze residential mortgage lending by banks in periods surrounding upgrades or downgrades in their ratings under the Community Reinvestment Act (CRA). Empirical results indicate that upgraded banks had higher relative levels of lending than did downgraded banks prior to ratings changes. Additionally, both downgraded and upgraded banks increased lending following implementation of reforms to the CRA in the 1990s, which were intended to more closely align rating assessment with lending outcomes. Little support is provided, on the other hand, for a hypothesis that banks respond to downgrades by increasing lending (despite apparent incentives for them to do so).
Rural‐Urban Migration and Control Theory
Authors: Osayimwese Iz.
Published: September 2010

In a largely expository style, a typical rural‐urban migration problem where urban unemployment is a central issue is modelled as a problem in optimal control. Some of the shortcomings of the Todaro specification of the expectations phenomenon in rural‐urban migration are discussed and an alternative specification is presented. The resulting optimal control model is solved in two alternative ways. First, Pontryagin's maximum principle, in spite of all its limitations, is used to generate some of the qualitative properties of the model, and some standard results are formalized. Secondly, a simple differential equation approach is employed to depict some essential qualitative features of the optimal control problem. Finally, some of the limitations of the optimal control model are discussed.
Explorations and Syntheses of Linear Programming And Spatial Interaction Models of Residential Location
Authors: Senior M. L. , Wilson A. G.
Published: September 2010

Various “linear programming” models of residential location are explored in some detail. It is then shown that entropy maximizing “sub‐optimal” versions of these can be developed, which may be more realistic at typical levels of resolution used for analysis but can still be given some of the interpretations of the programming models. Further, any programming model can be seen as a limiting case of some entropy maximizing model in which some of the parameters tend to infinity. Some empirical tests of both kinds of models are presented, and the limiting relationships are discussed.
On the Sources of Instability in the Rank‐Size Rule: Some Simple Tests of Gibrat's Law
Authors: Vining Daniel R.
Published: September 2010

While the implications of the Simon model of urban growth, e.g., the rank‐size rule, have been explored in numerous papers, the assumptions of that model have not, to my knowledge, been subjected to empirical verification. This paper represents an initial attempt to do so, emphasizing those sources of variation in the growth of cities typically singled out in Simon's verbal statements of the model: births, deaths, rural‐urban, urban‐rural, and urban‐urban migration. It is found that over the recent past the assumptions concerning these components are all violated and violated in the direction of upward curvature away from the log‐linear relationship between city size and rank predicted by the model, an upward curvature which we in fact observe.
The Conceptual Locus of a Two‐dimensional Language: Some Implications for Human Responses to Two‐dimensional Displays
Authors: Betak John F.
Published: September 2010

It is proposed that two‐dimensional displays, such as maps, aerial photographs, polygons, etc., may be generated and/or described by two‐dimensional languages. A simple perceptual device is posited which utilizes such a language. The device is comprised of at least two components which represent short‐term and long‐term memory. It is clear that its conceputal locus is in multisystem memory models. Three such models are characterized which provide the necessary and sufficient conditions for the perceptual model posited. Given this conceptual frame, three illustrative sets of implications and experiments for human responses to two‐dimensional displays are suggested.
Models of Space Searching in Urban Areas
Authors: Schneider Clarke H. P.
Published: September 2010

City dwellers occasionally must seek jobs, dwellings, or particular services or goods. Two very different ways exist by which the individual may conduct such a search. Lacking prior information, the person may elect to visit perceived possible locations until an appropriate one is found. Alternatively, an address may first be ascertained and then visited by finding a path to it. Clearly, there is a substantial difference between these two methods in terms of the amount of spatial movement they require in order to satisfy the searcher's needs. In this paper, this difference is modeled for situations that vary in terms of the density of acceptable end points of the search, as well as in characteristics of the signs of these end points, their patterns, and the level of information with which the searcher may begin.
Evaluation of the Poisson Approximation To Measures of the Random Pattern in the Square
Authors: Dacey Michael F.
Published: September 2010

Theoretical values for spacing between points of the Poisson process are frequently used to evaluate the hypothesis that the locations within a region of pointlike objects have a random pattern. These theoretical spacing values are an approximation to spacing values for a uniform process in which the objects are uniformly and independently located in the region. The adequacy of the Poisson approximation to this uniform process for a square region is evaluated by analytic and numeric methods. The approximation is close for a small number of points when spacing between objects is measured by toroidal distance.
Applications of the Location Set‐covering Problem
Authors: ReVelle Charles , Toregas Constantine , Falkson Louis
Published: September 2010

The location set‐covering problem is extended to apply to three new situations. (1) The demands are assumed to occur continuously alone arcs of a network. (2) A mobile unit departs from one of the locations to be chosen and picks up the demand, providing service at a still more distant point. (3) New demands and sites occur over time.
Some Problems in the Application of Factor Analysis in Geography
Authors: Chojnicki Zbyszko , Czyz Teresa
Published: September 2010

The article contains a discussion of three problems pertaining to the application of factor analysis in geography: the assumptions of factor analysis and principal components analysis, a descriptive and theoretical interpretation of factors, and research prospects for three‐way factor analysis of spatial and temporal variation.
An Information‐theoretic Analysis: An Application to Soviet‐COMECON Trade Flows
Authors: Semple R. Keith , Demko George J.
Published: September 2010

This paper develops a classificatory methodology designed to assign geographic entities to groupings based upon the multivariate flow profiles displayed by the entities and a dispersion statistic designed to detect dynamic shifts in these flow profiles over time. Information statistic, provide the mathematical basis of the analysis and the changing trade profiles of the member nations of COMECON provide an illustrative case study.
Information Integration Theory Applied to Student Apartment Selection Decisions
Authors: Louviere Jordan J. , Henley David A.
Published: September 2010

The purpose of this paper is to apply theory and methodology developed in the study of information integration in psychology to the modeling of individual apartment decisions. In particular, two models that express the trade‐off relationships among three variables hypothesized to be influential in apartment selection are examined. Although it is not claimed that the variables included in the study are the only ones relevant to apartment selection, evidence is provided that they are considered to be the three most important in a preliminary analysis. The paper also discusses potential benefits of controlled experimentation and model estimation strategies.
Production, Consumption, and the Allocation of Labor By a Peasant in a Periodic Marketing System
Authors: Jones Donald W.
Published: September 2010

The allocation of time by a part‐time marketer between subsistence production and marketing links production and consumption decisions in a periodic marketing system. Distinctions between full‐ and part‐time marketers are emphasized. The model of the part‐time trader predicts changes in the time devoted to each activity and in outputs as relative prices change. Interpretations can be made regarding the amount of effort devoted to, and the rewards from, periodic marketing.
The Aggregation Problem in Location‐Allocation
Authors: Goodchild Michael F.
Published: September 2010

Location‐allocation solutions based on aggregate estimates of demand are subject to error because of a loss of locational information during aggregation. It is shown that any method to remove or reduce uncertainty must be solution‐specific and therefore impractical, for both median and center classes of problems. The significance of the error is illustrated by simulation of solutions to a number of artificial and real problems. It is suggested that aggregation problems be specifically addressed in applications of location‐allocation models, and possible methods are proposed.
Location Modeling Utilizing Maximum Service Distance Criteria
Authors: Church Richard L. , Meadows Michael E.
Published: September 2010

The location set‐covering problem (LSCP) and the maximal covering location problem (MCLP) have been the subject of considerable interest. As originally defined, both problems allowed facility placement only at nodes. This paper deals with both problems for the case when facility placement is allowed anywhere on the network. Two theorems are presented that show that when facility placement is unrestricted, for either the LSCP or MCLP at least one optimal solution exists that is composed entirely of points belonging to a finite set of points called the network intersect point set (NIPS). Optimal solution approaches to the unrestricted site LSCP and MCLP problems that utilize the NIPS and previously developed solution methodologies are presented. Example solutions show that considerable improvement in the amount of coverage or the number of facilities needed to insure total coverage can be achieved by allowing facility placement along arcs of the network. In addition, extensions to the arc‐covering model and the ambulance‐hospital model of ReVelle, Toregas, and Falkson are developed and solved.
A Model of Pedestrian Route Choice and Demand for Retail Facilities within Inner‐City Shopping Areas
Authors: Borgers Aloys , Timmermans Harry
Published: September 2010

There are still only a few operational models of pedestrian movement. In particular, the gravity /entropy‐maximizing model has received most attention. In this paper a descriptive model of pedestrian movement is presented. It can be considered as an extension of O'Kelly's model of the demand for retail facilities in the presence of multistop, multipurpose trips. The model basically consists of three submodels: one for destination choice, one for route choice, and one for impulse stops. Together, these submodels describe/predict the total demand for retail facilities within inner‐city shopping areas. The model is applied to data from the city of Maastricht, The Netherlands.
Model Comparison and Model Validation Issues in Empirical Work on Urban Density Functions
Authors: Anselin Luc , Can Ayse
Published: September 2010

Urban population density functions, as summary descriptions of urban structure, have been based on a variety of theoretical specifications and implemented empirically on a wide scale. In this paper, some issues related to the estimation of density functions and the validation of different specifications are considered me closely. Particular attention is given to the selection of spatial observational units, the use of net or gross density measures, testing for spatial autocorrelation and heteroskedasticity, and the use of different model validation criteria (tests on rum‐nested hypotheses versus. measures of fit). An empirical illustration is provided with data for 1980 on the Columbus, Ohio, metropolitan area.
Programming Models for Facility Dispersion: The p‐Dispersion and Maxisum Dispersion Problems
Authors: Kuby Michael J.
Published: September 2010

The p‐dispersion problem is to locate p facilities on a network so that the minimum separation distance between any pair of open facilities is maximized. This problem is applicable to facilities that pose a threat to each other and to systems of retail or service franchises. In both of these applications, facilities should be as far away from the closest other facility as possible. A mixed‐integer program is formulated that relies on reversing the value of the 0–1 location variables in the distance constraints so that only the distance between pairs of open facilities constrain the maximization. A related problem, the maxisum dispersion problem, which aims to maximize the average separation distance between open facilities, is also formulated and solved. Computational results for both models for locating 5 and 10 facilities on a network of 25 nodes are presented, along with a multicriteria approach combining the dispersion and maxisum problems. The p ‐dispersion problem has a weak duality relationship with the (p‐1)‐center problem in that one‐half the maximin distance in the p‐dispersion problem is a lower bound for the minimax distance in the center problem for (p‐1) facilities. Since the p‐center problem is often solved via a series of set‐covering problems, the p‐dispersion problem may prove useful for finding a starting distance for the series of covering problems.
Lagrange Multiplier Test Diagnostics for Spatial Dependence and Spatial Heterogeneity
Authors: Anselin Luc
Published: September 2010

Several diagnostics for the assessment of model misspecification due to spatial dependence and spatial heterogeneity are developed as an application of the Lagrange Multiplier principle. The starting point is a general model which incorporates spatially lagged dependent variables, spatial residual autocorrelation and heteroskedasticity. Particular attention is given to tests for spatial residual autocorrelation in the presence of spatially lagged dependent variables and in the presence of heteroskedasticity. The tests are formally derived and illustrated in a number of simple empirical examples.
Multiple Outlets in a Duopoly: A First Entry Paradox
Authors: Ghosh Avijit , Buchanan Bruce
Published: September 2010

The strategic advantages of being the first entrant into a market have been discussed extensively. This paper presents examples of markets in which there is no first entry advantage. Rather, the later entrant always has an advantage even when both deploy equal resources. The necessary conditions for the occurrence of this first entry paradox are presented.
Aggregate Rent and Surplus Measurement in a von Thünen Model
Authors: O'Kelly M. E.
Published: September 2010

While theoreticians continue to debate the appropriateness of surplus measurement in a von Thünen crop model, examples of practitioners appealing to such measures can be found. This paper shows that the well known equivalence between aggregate location rent and producers' surplus, extends to the case of a nonhomogeneous transportation system. Specifically a transportation route running through the region improves access to the town and encourages an extension of the production region. Results in the paper show the equilibrium price for the crop (as a function of the quality of the improved route); an equivalence between aggregate rent and the surplus accruing to crop producers; and the existence of an area within which crop production is cut back after the transport route is opened.
The Urbanization Process with Moving Boundary
Authors: Zhang Wei‐Bin
Published: September 2010

The paper proposes a dynamic model of urbanization in the regional system consisting of the central business district (CBD), the urban, and the rural areas. Processes of “eating up” the rural land by the residents and firms in the urban area are endogenously determined. Spatial and temporal land prices of the urban and rural areas are described by partial differential equations. The boundary between the urban and rural areas is temporarily moved by “eating‐up” forces of the urban area. Movement of the boundary is determined by interactions between the urban and rural areas near the boundary. The model consists of three partial differential equations under appropriate boundary and initial conditions. It describes how the actual regional pattern is disturbed far away from the equilibrium by inflationary forces. An analytic solution of the fixed rural land price is given.
Price Variation in Spatial Oligopolies
Authors: Mulligan Gordon F. , Fik Timothy J.
Published: September 2010

The “geography of price” is being given renewed attention by geographers and economists. This paper examines spatial price variation in both unbounded (circular) and bounded (linear) one‐dimensional markets. Firms compete for consumers in the short run by adjusting price until the Bertrand equilibrium is reached in the market. While firms act as spatial oligopolists in specific market segments, the profit‐maximizing price of any given firm depends directly and indirectly upon the spatial‐economic properties (locations, marginal costs) of all other firms in the market.
A Dynamic Location‐Allocation Model for Evaluating the Spatial Impacts for Just‐in‐Time Planning
Authors: Osleeb Jeffrey P. , Ratick Samuel J.
Published: September 2010

This paper presents an interperiod network storage location‐allocation (INSLA) model to solve the just‐in‐time production planning problem. The model is extended to a multiobjective problem in which trade‐offs between delivery time and transportation costs are analyzed. The results for a hypothetical problem show that in an attempt to reduce inventories on the part of the primary purchaser of raw materials, the possibility exists for less than optimal behavior in the system.
An Interactive Approach to the Central Facility Location Problem: Locating Pediatric Hospitals in Warsaw
Authors: Malczewski Jacek , Ogryczak Włodzimierz
Published: September 2010

Most of the conventional approaches to the central facility location problem neglect the interaction of analyst and decision‐maker during the locational choice process. This paper presents a new interactive approach to the central facility location problem. It is assumed that the problem is formulated by an analyst as a multiobjective optimization problem. Then the decision‐maker searches for a satisfactory solution working directly with the computer system. The interactive procedure was implemented on IBM‐PC XT/AT as the decision support system DINAS (Dynamic Interactive Network Analysis System) which enables the solution of various multiobjective location‐allocation problems. DINAS has been successfully used for solving a real‐world planning problem, namely for finding locations for pediatric hospitals in the Warsaw region.
Spatial Search for the Lowest Price
Authors: Rogerson Peter A.
Published: September 2010

Search for low prices often requires that individuals make decisions not only about the optimal amount of search, but also about the optimal route to be taken through a set of known locations. In this paper, the fixed sample size strategy used in economic models of search is extended to account for the travel costs that are incurred as alternatives are examined. Analytical results for the optimal amount of search are given, and alternative routing algorithms for a modified version of the traveling‐salesman problem are evaluated.
Methods of Mapping and Identifying Small Clusters of Rare Diseases with Applications to Geographical Epidemiology
Authors: Alexander Freda E. , Ricketts T. James , Williams Joan , Cartwright Ray A.
Published: September 2010

Geographical variation operates at a variety of scales. Methods of mapping variation in disease incidence between different countries or even counties are relatively well developed. When, however, the question relates to much smaller aggregations (that is, “clustering”), attention has mainly been restricted to areas near putative point hazards; the majority of cases are excluded from such an investigation. In this study we show how clustering may be investigated and displayed in such a way that it becomes a powerful tool in epidemiological research. As examples we use incidence data from the Yorkshire health region for selected childhood cancers and adult haematopoietic malignancies. The methods would readily extend to any small clusters of rare events.
Modeling Categorical Data with Chi Square Automatic Interaction Detection and Correspondence Analysis
Authors: Clark W.A.V. , Deurloo M. C. , Dieleman F. M.
Published: September 2010

For the past decade we have been concerned with the application of categorical data techniques to mobility and housing choice. In a previous issue of this journal we reviewed a number of these modeling techniques. We now extend that earlier work by introducing correspondence analysis as a geometric interpretative technique that fits in an intermediate position between CHAID and nested logit analysis. The method is illustrated on the same housing and tenure choice data as was used in the previous paper.
Multicollinearity and Parameter Estimation in Simultaneous‐Equation Models of Fluvial Systems
Authors: Rhoads Bruce L.
Published: September 2010

Simultaneous‐equation statistical models are an attractive method for directly analyzing interactions among components of geomorphic systems. This study demonstrates that the utility of simultaneous‐equation analysis is limited for fluvial systems by inherent multicollinearity among hydrologic and morphologic variables. Although multicollinearity for observed data may not be severe, estimation procedures for simultaneous‐equation models often enhance this multicollinearity to problematic levels. Diagnostic tests are applied to three models of fluvial systems to illustrate the severity of the problem. It is recommended that investigators who develop simultaneous‐equation models perform appropriate diagnostic evaluations to determine the impact of multicollinearity on specific parameter estimates.
Variations in the Spatial Pattern of Settlement Locations: An Analysis Based on Proportional Hazards Models
Authors: Odland John , Ellis Mark
Published: September 2010

Models based on hazard functions are used to analyze spatial trends in the distance intervals separating point locations. The proportional hazards model, which has been widely applied to analyze intervals of time, is used to investigate variation in the spacing of settlements in Nebraska. This model allows spatial trends in the intervals between settlements to be investigated under very general conditions regarding the interdependence of settlement locations and permits the coordinate locations of the intervals to be treated as spatially varying covariates. An empirical analysis reveals an East‐West trend in the spacing of settlements.
Impacts of Multiple‐Period Lags in Dynamic Logit Models
Authors: Nijkamp Peter , Reggiani Aura
Published: September 2010

This paper will provide an introduction to a new field of research, viz. the sensitivity of the solution trajectory of a dynamic logit model (belonging to the class of discrete choice models) in the light of a multiperiod lag structure. It is well known from recent advances in the area of chaos and turbulence theory that the stability of a dynamic system is critically dependent on various factors, such as threshold values of parameters, initial conditions, and also the lag structure. This paper aims to identify the consequences of different lag structures in dynamic logit models (including also dynamic spatial interaction models). Various simulation experiments will be used to show that the onset of instability of the solution trajectory tends to decrease as the number of time lags increases (depending also on the growth rate of the system).
Network Autocorrelation in Transport Network and Flow Systems
Authors: Black William R.
Published: September 2010

The use of Moran'sIto assess the existence of network autocorrelation in flows over the arcs of real (tangible) and abstract (intangible) networks is examined. Residuals of a migration model developed here reveal the presence of such autocorrelation or dependence. Two approaches for removing the observed dependence are examined.
Spatial Diffusion of the HIV/AIDS Epidemic: Modeling Implications and Case Study of AIDS Incidence in Ohio
Authors: Golub Andrew , Gorr Wilpen L. , Gould Peter R.
Published: September 2010

This paper extends a compartmental epidemiological model for HIV transmission and AIDS incidence to include hierarchical and expansion spatial diffusion. An implication of the resultant model is that hierarchical diffusion causes the large infection growth rates of densely populated areas at the top of the central places hierarchy to “chain” down and dominate small local growth rates during the exponential‐growth phase of the epidemic. Also, hierarchical diffusion causes a high transient growth rate in the first few years of a local epidemic. The spatial compartmental model fits observed AIDS incidence spatial diffusion patterns in Ohio reasonably well.
Fractal Simplification of Lines Using Convex Hulls
Authors: Normant François , Tricot Claude
Published: September 2010

We investigate the problem of the simplification of a curve from a geometric viewpoint. Starting from a fractal hypothesis, we consider that the best methods are those that keep an estimated value of the fractal dimension constant, before and after simplification. We propose a simplification rule based on the use of local convex hulls that corresponds to a new algorithm for computing fractal dimension. This algorithm is both accurate and universal, and does not imply the need to make arbitrary hypotheses regarding the structure of the curve. A comparison is made with other fractal approaches and with the well‐known Douglas‐Peucker method.
Selected Characteristics of Soviet Foreign Trade and Implications for the Foreign Trade of the Commonwealth of Independent States
Authors: Hanink Dean M. , Kier Valerie
Published: September 2010

This paper provides observations on recent patterns of the Soviet Union's foreign trade in the context of factor endowment trade theory and two models drawn from the new trade theory. Empirical analysis indicates that recent Soviet foreign trade was not based on differing factor intensities between Soviet goods and the those of the rest of the world. Instead, the recent geography of Soviet foreign trade suggests that it conformed more to the trade in differentiated products expected under the new trade theory. These results suggest that Soviet foreign trade had developed in such a way that, at least with respect to merchandise trade, the Commonwealth of Independent States (CIS) has a strong potential for fairly rapid integration within the group of industrial countries.
A Factorial Model of Aggregate Spatio‐Temporal Behavior: Application to the Diurnal Cycle
Authors: Goodchild Michael F. , Klinkenberg Brian , Janelle Donald G.
Published: September 2010

The cross‐sectional nature of much social data, coupled with the static view provided by maps and current spatial data handling software, have produced a tradition of research on urban spatial structure that is largely two‐dimensional and derived from residential locations. The paper presents an analysis of a space‐time diary data set collected in Halifax, Nova Scotia. A series of transformations are used to convert the individual diary records to a three‐mode matrix of intensities, which is then analyzed using the PARAFAC three‐mode factor model. Home/work is found to be the strongest organizing dimension of the urban space‐time, followed by entertainment, shopping, and education / work. We show how these dimensions appear to varying degrees in different locations, time periods, and human activities. The paper argues for a dynamic view of urban spatial structure in which only the physical facilities remain static.
Kriging the Local Risk of a Rare Disease from a Register of Diagnoses
Authors: Webster R. , Oliver M. A. , Muir K. R. , Mann J. R.
Published: September 2010

A substantial problem in studying the geographical epidemiology of rare noncontagious diseases is to estimate the risks of their development within populations. A geostatistical solution is described and illustrated by a case study of cancer among children in the West Midlands of England for the years 1980 to 1984 inclusive. Data consist of the numbers of diagnosed cases of cancer and of healthy children in each of 838 electoral wards, the centroids of which are known accurately. The rate of incidence or frequency, equal to the number of cases divided by the number of children, is a binomial variable and is treated as a realization of the underlying risk of a child's developing the disease that varies from place to place. The experimental variogram of the frequency was computed using the standard formulation. The variogram of the risk was obtained from it taking into account the numbers of children at risk and the error associated with each observed frequency. The variogram of the risk increased monotonically from 0 at zero lag to about 50 kilometers, and it was modeled as Whittle's two‐dimensional elementary correlation function. The covariances of frequency and cross‐covariances between the frequency and the risk were derived from it, and these were then used together with the data to krige the risk and map it. The risk of developing the disease is shown to have a patchy distribution, strongly autocorrelated at the regional scale of the investigation.