bluuebunny/crossref_metadata_2025 huggingface dataset:
The Blood–Brain Barrier: Geriatric Relevance of a Critical Brain–Body Interface
Authors: Zeevi Neer , Pachter Joel , McCullough Louise D. , Wolfson Leslie , Kuchel George A.
Published: September 2010

The blood–brain barrier (BBB) represents the interface between the brain and other body tissues. Its ability to protect the brain from harmful compounds has attracted the attention of clinicians and investigators, but far from being a simple physical barrier, the BBB is a complex, heterogeneous, and dynamic tissue. The integrated function of the cerebral microvasculature, tight junction proteins, brain microvascular endothelial cells (BMECs), cellular transport pathways, and enzymatic machinery jointly contribute to normal BBB integrity. Aging, systemic diseases, and ischemic injury can disrupt these processes, resulting in a decline in overall BBB function and integrity. Based on the published literature, this study proposes that age‐ and disease‐related BBB alterations play a key role in diminishing the ability of older patients to recover from acute ischemic stroke. Evidence linking deficits in the cerebral microvasculature and BBB integrity to dementia, medication‐related cognitive decline, white matter disease (WMD or leukoaraiosis), and related geriatric syndromes including delirium, gait disorders, and urinary incontinence is also reviewed. Priority areas for a future research agenda include strategies to improve clinicians' ability to diagnose, prevent, and manage BBB abnormalities. In future years, in vivo measures such as functional and contrast‐enhanced neuroimaging will be used to evaluate BBB integrity in older adults while also assessing the effectiveness of interventions, some targeting inflammatory pathways known to disrupt the BBB, for their ability to prevent or slow the progression of these complex multifactorial geriatric syndromes.
Geriatric Impairments and Disability: The Cardiovascular Health Study
Authors: Chaudhry Sarwat I. , McAvay Gail , Ning Yuming , Allore Heather G. , Newman Anne B. , Gill Thomas M.
Published: September 2010

OBJECTIVES: To determine the relative importance of geriatric impairments (in muscle strength, physical capacity, cognition, vision, hearing, and psychological status) and chronic diseases in predicting subsequent functional disability in longitudinal analyses.

DESIGN: Longitudinal data from the Cardiovascular Health Study were analyzed. Multivariable Cox hazards regression modeling was used to analyze associations between time‐dependent predictors and onset of disability in activities of daily living (ADLs) and mobility.

SETTING: Four communities across the United States (Sacramento County, CA; Washington County, MD; Forsyth County, NC; and Allegheny County, PA).

PARTICIPANTS: Five thousand eight hundred eighty‐eight elderly persons.

MEASUREMENTS: Data were collected annually through in‐person examinations.

RESULTS: ADL disability developed in 15% of participants and mobility disability in 30%. A single multivariable model was developed that included demographics, marital status, body mass index, and number of impairments and diseases. The hazard ratios (HRs) of having one, two, and three or more geriatric impairments (vs none) for the outcome of ADL disability were 2.12 (95% confidence interval (CI)=1.63–2.75), 4.25 (95% CI=3.30–5.48), and 7.87 (95% CI=6.10–10.17), respectively, and for having one, two, and three or more chronic diseases were 1.75 (95% CI=1.41–2.19), 2.45 (95% CI=1.95–3.07), and 3.26 (95% CI=2.53–4.19), respectively. Similarly, the HRs of having one, two, and three or more impairments for the outcome of mobility disability were 1.48 (95% CI=1.27–1.73), 2.08 (95% CI=1.77–2.45), and 3.70 (95% CI=3.09–4.42), respectively, and for having one, two, and three or more diseases were 2.06 (95% CI=1.76–2.40), 2.80 (95% CI=2.36–3.31), and 4.20 (95% CI=3.44–5.14), respectively.

CONCLUSION: Number of geriatric impairments was more strongly associated than number of chronic diseases with subsequent ADL disability and nearly as strongly associated with the subsequent mobility disability.
Comparative Effectiveness of White Blood Cell Growth Factors on Neutropenia, Infection, and Survival in Older People with Non‐Hodgkin's Lymphoma Treated with Chemotherapy
Authors: Gruschkus Stephen K. , Lairson David , Dunn J. Kay , Risser Jan , Du Xianglin L.
Published: September 2010

OBJECTIVES: To determine the effect of colony‐stimulating factor (CSF) on incidence of febrile neutropenia, infection, and survival in older people with non‐Hodgkin's lymphoma (NHL) treated with chemotherapy.

DESIGN: Retrospective cohort study.

SETTING: The Surveillance, Epidemiology, and End Results–Medicare database.

PARTICIPANTS: Thirteen thousand two hundred twenty‐three people diagnosed with NHL at age 65 and older (mean age 74.9, range 65–102) in 1992 to 2002 who received chemotherapy within 12 months of diagnosis.

MEASUREMENTS: Primary prophylaxis was defined as CSF administered at the start of chemotherapy before febrile neutropenia or infection; secondary prophylaxis was defined as CSF use after febrile neutropenia or infection.

RESULTS: Participants with five to nine administrations of primary prophylactic CSF had a 42% lower risk of febrile neutropenia (odds ratio (OR)=0.58, 95% confidence interval (CI)=0.41–0.83), and participants with 10 or more administrations had a 48% lower risk (OR=0.52, 95% CI=0.36–0.76) after adjusting for age, stage, histology, and comorbidity. Results did not differ significantly after adjusting for propensity score of receiving CSF. There was no significant association between primary prophylactic CSF and overall survival, but secondary prophylactic CSF was significantly associated with better survival. Four to 10 administrations of secondary prophylactic CSF was associated with 9% lower mortality risk (hazard ratio (HR)=0.91, 95% CI=0.84–0.99), 11 to 23 administrations was associated with 23% lower mortality risk (HR=0.77, 95% CI=0.71–0.84) and 24 or more administrations was associated with 13% lower mortality risk (HR=0.87, 95% CI+0.79–0.95) than in participants not receiving CSF after neutropenia or infection.

CONCLUSION: Primary prophylactic CSF was observed to be effective in reducing the incidence of neutropenia and infection. These findings substantiate the clinical guidelines for recommending prophylactic CSF in older people with NHL receiving chemotherapy.
To Sleep, Perchance to Seize: Surgery Ameliorates Nocturnal Frontal Lobe Seizures
Authors: Hirsch Lawrence J.
Published: September 2010

Surgical Treatment of Drug-resistant Nocturnal Frontal Lobe Epilepsy. Nobili L, Francione S, Mai R, Cardinale F, Castana L, Tassi L, Sartori I, Didato G, Citterio A, Colombo N, Galli C, Lo Russo G, Cossu M. Brain 2007;130 (Pt 2):561–573. Of the cases with nocturnal frontal lobe epilepsy (NFLE) 30% are refractory to antiepileptic medication, with several patients suffering from the effects of both ongoing seizures and disrupted sleep. From a consecutive series of 522 patients operated on for drug-resistant focal epilepsy, 21 cases (4%), whose frontal lobe seizures occurred almost exclusively (>90%) during sleep, were selected. All patients underwent a comprehensive pre-surgical evaluation, which included history, interictal EEG, scalp video-EEG monitoring, high-resolution MRI and, when indicated, invasive recording by stereo-EEG (SEEG). There were 11 males and 10 females, whose mean age at seizure onset was 6.2 years, mean age at surgery was 24.7 years and seizure frequency ranged from <20/month to >300/month. Nine patients reported excessive daytime sleepiness (EDS). Prevalent ictal clinical signs were represented by asymmetric posturing (6 cases), hyperkinetic automatisms (10 cases), combined tonic posturing and hyperkinetic automatisms (4 cases) and mimetic automatisms (1 case). All patients reported some kind of subjective manifestations. Interictal and ictal EEG provided lateralizing or localizing information in most patients. MRI was unrevealing in 10 cases and it showed a focal anatomical abnormality in one frontal lobe in 11 cases. Eighteen patients underwent a SEEG evaluation to better define the epileptogenic zone (EZ). All patients received a microsurgical resection in one frontal lobe, tailored according to pre-surgical evaluations. Two patients were operated on twice owing to poor results after the first resection. Histology demonstrated a Taylor-type focal cortical dysplasia (FCD) in 16 patients and an architectural FCD in 4. In one case no histological change was found. After a post-operative follow-up of at least 12 months (mean 42.5 months) all the 16 patients with a Taylor's FCD were in Engel's Class Ia and the other 5 patients were in Engel's Classes II or III. After 6 months post-surgery EDS had disappeared in the 9 patients who presented this complaint pre-operatively. It is concluded that patients with drug-resistant, disabling sleep-related seizures of frontal lobe origin should be considered for resective surgery, which may provide excellent results both on seizures and on epilepsy-related sleep disturbances. An accurate pre-surgical evaluation, which often requires invasive EEG recording, is mandatory to define the EZ. Further investigation is needed to explain the possible causal relationships between FCD, particularly Taylor-type, and sleep-related seizures, as observed in this cohort of NFLE patients.
Epilepsy and Forgetfulness: One Impairment, Multiple Mechanisms
Authors: Mazarati Andrey
Published: September 2010

Impaired Single Cell Firing and Long-term Potentiation Parallels Memory Impairment Following Recurrent Seizures. Zhou JL, Shatskikh TN, Liu X, Holmes GL. Eur J Neurosci 2007;25(12):3667–3677. Patients with epilepsy are at substantial risk for memory impairment. Animal studies have paralleled these clinical observations, demonstrating impaired hippocampal function as measured by spatial memory in rodents subjected to seizures. However, the mechanism of seizure-induced hippocampal impairment is unclear. Here we investigated the effects of recurrent seizures on water-maze performance, a behavioural measure of learning and memory, long-term potentiation (LTP; considered a test of synaptic plasticity and memory) and place-cell firing patterns, a single-cell indicator of spatial memory. LTP and CA1 place-cell activity were examined in separate groups of freely moving rats, before and after 10 flurothyl-induced seizures. Water maze performance was examined in a third group of rats, five with previously induced seizures and five controls. Recurrent flurothyl seizures were associated with marked impairment in LTP and a reduction in the frequency of the peak theta power. Compared to baseline recordings, place-cell firing patterns following recurrent seizures were significantly less precise, had lower firing rates and were less stable. Impaired place-cell firing was seen as early as after two seizures and persisted at least 72h after the last seizure. Water-maze performance was also significantly impaired in animals that underwent recurrent seizures. No cell loss or synaptic reorganization was observed in the hippocampus or in several other cortical areas that are vulnerable to seizures. These results demonstrate that relatively brief excitatory events, not producing visible cell damage, can nevertheless cause long-lasting changes in hippocampal physiology, observable as impairments in place-cell function, LTP and spatial memory.
Antiepileptogenesis Therapy with Levetiracetam: Data from Kindling versus Status Epilepticus Models
Authors: Dudek F. Edward , Bertram Edward H. , Staley Kevin J.
Published: September 2010

Prophylactic Treatment with Levetiracetam after Status Epilepticus: Lack of Effect on Epileptogenesis, Neuronal Damage, and Behavioral Alterations in Rats. Brandt C, Glien M, Gastens AM, Fedrowitz M, Bethmann K, Volk HA, Potschka H, Löscher W. Neuropharmacology 2007;53(2):207–221. Levetiracetam (LEV) is a structurally novel antiepileptic drug (AED) which has demonstrated a broad spectrum of anticonvulsant activities both in experimental and clinical studies. Previous experiments in the kindling model suggested that LEV, in addition to its seizure-suppressing activity, may possess antiepileptogenic or disease-modifying activity. In the present study, we evaluated this possibility by using a rat model in which epilepsy with spontaneous recurrent seizures (SRS), behavioral alterations, and hippocampal damages develop after a status epilepticus (SE) induced by sustained electrical stimulation of the basal amygdala. Two experimental protocols were used. In the first protocol, LEV treatment was started 24h after onset of electrical amygdala stimulation without prior termination of the SE. In the second protocol, the SE was interrupted after 4h by diazepam, immediately followed by onset of treatment with LEV. Treatment with LEV was continued for 8weeks (experiment #1) or 5weeks (experiment #2) after SE, using continuous drug administration via osmotic minipumps. The occurrence of SRS was recorded during and after treatment. In addition, the rats were tested in a battery of behavioral tests, including the elevated-plus maze and the Morris water maze. Finally, the brains of the animals were analyzed for histological lesions in the hippocampal formation. With the experimental protocols chosen for these experiments, LEV did not exert antiepileptogenic or neuroprotective activity. Furthermore, the behavioral alterations, e.g., behavioral hyperexcitability and learning deficits, in epileptic rats were not affected by treatment with LEV after SE. These data do not support the idea that administration of LEV after SE prevents or reduces the long-term alterations developing after such brain insult in rats.
Risk Shifting through Nonfinancial Contracts: Effects on Loan Spreads and Capital Structure of Project Finance Deals
Authors: CORIELLI FRANCESCO , GATTI STEFANO , STEFFANONI ALESSANDRO
Published: September 2010

We study capital structure negotiation and cost of debt financing between sponsors and lenders using a sample of more than 1,000 project finance loans worth around US$195 billion closed between 1998 and 2003. We find that lenders: (i) rely on the network of nonfinancial contracts as a mechanism to control agency costs and project risks, (ii) are reluctant to price credit more cheaply if sponsors are involved as project counterparties in the relevant contracts, and finally (iii) do not appreciate sponsor involvement as a contractual counterparty of the special purpose vehicle when determining the level of leverage.
The High‐Frequency Response of the EUR‐USD Exchange Rate to ECB Communication
Authors: CONRAD CHRISTIAN , LAMLA MICHAEL J.
Published: September 2010

We investigate the impact of the European Central Bank's monetary policy communication during the press conference held after the monthly Governing Council meeting on the EUR‐USD exchange rate in high frequency. Based on the method of Content Analysis, we construct communication indicators for the introductory statement and find that communication with respect to future price developments is most relevant. In response to statements about increasing risks to price stability the EUR appreciates on impact. To the contrary, communication about economic activity and monetary aggregates does not generate significant exchange rate reactions.
An Assessment of the Action Component Of Action Space
Authors: Higgs Gary
Published: September 2010

Action spaces and the related topics of human spatial behavior patterns have been the subject of a great many studies. Despite this, theory development in behavioral geography has not proceeded rapidly. The slow progress in the theoretical area of behavioral geography in general, and action space in particular, may be attributed to the fact that the action‐space concept combines the diverse elements of perception, action, preference, and potential activity into one elusive term. Theory development might be facilitated if these elements were separated and an operational definition established. This paper presents an operational definition and description of the action component of action spaces and evaluates the application and utility of the concept in the study of spatial behavior patterns.
The Lösch System of Market Areas: Derivation and Extension
Authors: Beavon Keith S. O. , Mabin Alan S.
Published: September 2010

Certain aspects of Lösch's classic work on the network of markets and the system of networks have not yet been clearly explained in the literature. Lösch did not describe his derivation procedures in full, and apparent printing errors in certain förmulae confuse the issue further, with the result that several recent texts reproduce Lösch's diagrams but offer no explanation of how they are constructed. Accepting the network of hexagonal market areas for a continuous system of markets, given an even but discrete distribution of population, the derivation from first principles of the complete system of different market areas is presented. Apparent errors in the translated text of Lösch's work are corrected. Limitations in some other authors' work and accordance with earlier empirically derived formulae are mentioned. The production of “city‐rich” and “city‐poor” sectors is shown to be a constraint on, rather than a result of, the system, and Lösch's statement that the coincidence of centers is maximized is clarified. The extension of the Lösch system to the internal tertiary structure of the city is presented and attention drawn to the empirical attractiveness of this approach.
Set‐determined Process and the Growth of Spatial Structure
Authors: Smith Terence R.
Published: September 2010

We present an analysis of the effects of different information flow patterns on the growth of spatial structure in a broad class of systems. Examples are drawn from plant and message diffusion processes, the growth of herding in animal populations and, in particular, the evolution of cities in human populations. We model the actions of an “individual” as a response to gradients in a transformation of the “real” space, this transformation being the individual's information map of the space. Interesting deductions occur as a result of allowing the individual's information map to vary from extremely local to extremely global. In the city growth model for example, if migration decisions are based upon extremely local information, then the system is characterized by instability and the lack of any well‐defined spatial structure. As the localness of this information map decreases, the system is characterized by the development of well defined spatial structure with a characteristic distance separating the “cities.” In a particular case, we show that the wavelength of the dominant spatial structure is directly related to the size of an individual's information field. These effects are a consequence of interactions between individuals that arise from the nonlocalness of the information fields. We interpret the early growth stages in these models in terms of linear filters.
Semantic Structure and Perceived Environment
Authors: Desbarats Jacqueline M.
Published: September 2010

Most data‐gathering tasks for eliciting information about the structure of spatial images tend to impose predetermined arbitrary dimensions or categories on the subjects' responses. This paper, in contrast, makes use of an unstructured task (word association) from which measures of semantic similarity between metropolitan areas in California are generated. The interpretation of the areal groupings derived from the analysis of these data by a clustering method reveals the importance of location and size of urban areas in cognitive organization. When the dimensions underlying perceived similarities between places are extracted by a factor analytic model, climatic and environmental dimensions are found to account for more variance in the word‐association data than do social dimensions.
Streams, Slopes, and Suburban Development
Authors: Graf William L.
Published: September 2010

The percent of available relief in the form of free‐face slope and the percent of valley width as floodplain change systematically throughout drainage networks in response to changes in network position. The energy level and discharge of streams at the bases of slopes may be assessed by means of a cumulative stream‐ordering system wherein the stream order is directly related to discharge. Investigations of several small drainage basins on the rim of the Denver Basin, Colorado, by means of field measurements, interpretation of aerial photography, and operation of a computer model provide data that indicate that the distribution of near‐channel slopes responds to changes in land use, and particularly to suburban development. Increasing suburban development causes increases in the size and frequency of both free faces and floodplains.
A Classification of Spatial Distributions Based upon Several Cell Sizes
Authors: Liebetrau Albert M. , Rothman Edward D.
Published: September 2010

Several procedures, based upon cell count analysis, have been proposed for classifying spatial distributions, or maps, associated with some region R. Such procedures are rather imprecise and are known to depend upon the sixes and shapes of the cells in the particular partition of R under consideration.

In this paper, the problem is considered from the point of view of hypothesis testing. A test of randomness based upon an arbitrary number of partitions of R is giuen. If the hypothesis of randomness is rejected, additional tests may be performed to classify the map into one of two categories, clustered or regular.

These tests provide a number of advantages over existing procedures. Based upon multiple partitions of R, they decrease the dependence upon any particular partition, and the colresponding classification is precise since the null hypothesis distribution of the test statistic is (asymptotically) known. Finally, they allow a great deal of flexibility in testing for certain alternatives to randomness, and are applicable to one‐, two‐, and three‐ dimensional maps.
Lattice Tuning
Authors: Tobler W. R.
Published: September 2010

A method of spatial interpolation from an arbitrary arrangement of numerical observations is derived, with examples shown as contour maps. The fit to the original data and the smoothness of the resulting lattice values are optimized simultaneously by an iterative numerical technique. The algorithm does not require specification of distance dependent influence functions.
Gravity Parameter Estimation
Authors: Sheppard Eric S.
Published: September 2010

The question of whether ordinary least‐squares (OLS) regression provides unbiased estimates for parameters of the gravity model is investigated. Holding attractiveness constant and looking only at the location of destinations, OLS is shown to give unbiased estimates if underlying behavior conforms to the gravity hypothesis. Johnston's conjectures on this are examined and found to explain only partially observed variations in distance exponents. Allowing attractiveness to vary, spatial autocorrelation in attractiveness is shown to lead to bias in OLS estimation due to misspecification, even where behavior conforms to the gravity hypothesis. Deterministic and stochastic illustrations are provided.
Redundancy as an Index of Change in Point Pattern Analysis
Authors: Lews Ralph
Published: September 2010

Point pattern analysis based on concepts from information theory can go beyond existing techniques. Direct measurement of spatial form is achieved when Thiessen polygons are constructed around the points; in this scheme, each point's proportion of total area may be treated like a probability. Three information‐theoretic indices are available for analysis of a distribution of such probabilities. Entropy is density dependent. Redundancy, defined as the difference between observed and maximum entropy, seems to avoid this problem when the number of individuals in a pattern exceeds twenty. Comparisons of prior and posterior redundancy provide an indication of change in overall pattern form. An information gain expectation reflects changes for each individual in a pattern. Here, point‐area redundancy parameters are determined for Poisson‐generated patterns, using a gamma distribution of polygon areas and a computer‐generated set. An application to an urban crime problem illustrates the use of these parameters in the analysis of pattern change.
On the Road to Colonus: Or Theory and Perversity in the Social Sciences
Authors: Gould Peter
Published: September 2010

It is late afternoon, and two figures are seen walking slowly along a path that leads through laurel, olives, and vines towards white Colonus, earth's loveliest, where the nightingales liquid notes most haunt the darkness of green glades. They are deep in conversation, yet move with steady, purposeful strides towards an inn that cools its crisp Demesticha in the flowing waters of a spring.
Analyzing Cross‐classified Data with Inherent Spatial Dependence
Authors: Fingleton Bernard
Published: September 2010

Despite considerable recent progress in the methods available for the log‐linear analysis of categorical data arising from complex sampling schemes, only a few papers have been published that deal with the parallel phenomenon of dependence induced by spatial sampling. This paper aims to add to the general awareness of this topic and suggests some new ideas for tackling the problems raised. In the paper it is shown that the method that has been proposed for the valid selection of log‐linear models given spatially dependent data and some derivative methods are somewhat conservative when compared to an approach based on a model of spatial dependence outlined in section 4. The method also serves as a data exploratory technique to enhance the use of the more robust conservative approach.
Urban Neighborhoods as a National Resource: Irreversible Decisions and Their Equity Spillovers
Authors: Wolpert Julian , Seley John E.
Published: September 2010

The differential timing and pace of private versus public sector disinvestments in declining neighborhoods have some positive spillovers for their residents. Public services are not withdrawn or reduced as rapidly as private investments and the opportunity is preserved for future redevelopment or rehabilitation. This “public service bonus” is vulnerable, however, during periods of austerity and general retrenchment. During such crises, the pressures to rationalize service provision are able to overcome local political and bureaucratic resistance to service reallocations. The analysis is based upon the investment theory literature dealing with irreversible decisions and is exemplified by the reallocation of services in New York City's declining neighborhoods during the past decade.
Time Averages, Climatic Change, and Predictability
Authors: Burt James E.
Published: September 2010

Traditional averaging procedures (e.g., annual average, climatic normals) are shown to have both theoretical and practical failings when used for prediction or for detection of small climatic changes. Transformation of a multivariate autoregressive process (predictable components analysis) provides a useful way to construct empirical functions capturing the dynamic behavior of climatic variables.
Modeling Discontinuous Change in Retailing Systems: Extensions of the Harris‐Wilson Framework With Results From a Simulated Urban Retailing System
Authors: Fotheringham A. Stewart , Knudsen Daniel C.
Published: September 2010

This paper provides a test of an extension to the Harris‐Wilson (1978) model for examining discontinuous change in retailing systems. While the Harris‐Wilson model has been used almost exclusively to examine discontinuous change in the size of retail outlets, Fotheringham (1985) and Fotheringham and Knudsen (1986b) have recently shown it can be extended to model discontinuous change in the size and the relative location of retail outlets. Here, we present a test of this extension in a simulated urban retailing system. We also consider in more depth the supply side of the Harris‐Wilson framework and show how discontinuous changes between non‐zero equilibria can be modeled. Until now this has been impossible due to the previously restricted nature of the model. The generalization presented and examined here also allows an investigation of the trade‐off between the size and the location of retail outlets and of the effects of different types of consumer shopping behavior.
Activity Levels at Hub Facilities in Interacting Networks
Authors: O'Kelly M. E.
Published: September 2010

Hubs are a special type of central facility which are designed to act as switching points for intemodal flows. For instance, a set of ten interacting cities might all be connected to one of two major hubs. All flows between the cities would then be routed via the hubs. There is an obvious saving in the number of routes necessary to interconnect the cities when hubs are utilized, with a concomitant high level of activity at the facilities. This paper takes a heuristic approach to the evaluation of networks and hub locations to find locally optimal designs. It is shown that minimization of transportation costs may require assignment of nodes to a facility other than the nearest. A discount on the interhub transportation costs promotes a wider spacing of facilities. In a system with several hubs, minimization of total hub usage tends to concentrate demand very heavily into one central facility.
Land Use Transition and Deforestation in Developing Countries
Authors: Walker Robert T.
Published: September 2010

Deforestation in developing countries frequently occurs when logging interests abandon cut plots to farmers, who then make use of the land by producing either cash or food crops. This paper presents a model of land use transition that reveals conditions under which logging interests abandon cut plots to follow‐on farmers. The model incorporates key characteristics of forest utilization contracts so that the effects of particular contracts may be observed. Thus, the model serves as a basis for designing contracts that can help control deforestation.
Dynamic Models of Agricultural Location in a Spatial Interaction Framework
Authors: Wilson A. G. , Birkin M.
Published: September 2010

Recent research demonstrates that spatial interaction models may also be made to function as location models by the addition of appropriate hypotheses about structural adjustment. An appealing feature of the approach is that dynamics are explicitly incorporated. In this paper, the attempt is made to recast a problem from classical economic‐geographic theory—that of agricultural location—within a spatial interaction framework. It is shown that a wide variety of models is potentially available, and the properties of a range of these models are selectively explored.
Toward a Theory of Spatial Statistics: Another Step Forward
Authors: Griffith Daniel A.
Published: September 2010

An update is presented to an earlier piece outlining some steps that needed to be taken toward the establishment of a theory of spatial statistics. Findings that have appeared since this first paper are summarized and interpreted, and extensions and suggestions are offered for the further establishment of a basis for a theory of spatial statistics. Topics include boundary considerations, the role of latent spatial dependencies, and small‐sample‐size issues. These topics embrace the problems of data transformations, edge effect bias, reference sampling distributions, multivariate autocorrelation models, conditional expectations, and higher‐order autoregressive structures. In part, a course is charted for the next step to be taken.
The Dynamics of Metropolitan Change
Authors: Batten David , Johansson Börje
Published: September 2010

A collaborative research project entitled “Nested Dynamics of Metropolitan Processes and Policies” was initiated at the International Institute for Applied Systems Analysis in 1982. The ultimate objective is to enhance our primitive understanding with respect to interacting metropolitan change processes which are operating at significantly different speeds. In this introductory paper, some aspects and results of the project are summarized prior to a short discussion of the three related papers which follow in this volume.
A Dynamic Household Model for the Housing Market of Amsterdam
Authors: Rima Annemarie , van Wissen Leo , Nijkamp Peter
Published: September 2010

This paper addresses the issue of incorporating household dynamics into operational dynamic urban models. Dynamic model approaches that can be used to model urban change are introduced and discussed. We conclude that these different approaches are best combined in an accounting framework. An example of an accounting framework for a dynamic model of Amsterdam is presented. The household submodel is discussed in detail and some preliminary results are given.
Analysis of Dynamic Spatial Interaction Models by Means of Optimal Control
Authors: Nijkamp Peter , Reggiani Aura
Published: September 2010

This paper deals with the design of general classes of dynamic spatial interaction models. On the basis of a general (well‐behaved) multiperiod objective function and of a dynamic model representing the evolution of a spatial interaction system, an optimal control model is constructed. Particular attention is given to the equilibrium and stability conditions. It turns out that it is possible to identify steady‐state solutions for a dynamic spatial interaction model. Furthermore, it can also be demonstrated that the entropy model is a specific case of this spatial interaction system. A simple illustration for urban dynamics is given as well.
Building an Automated Modeling System to Explore a Universe of Spatial Interaction Models
Authors: Openshaw Stan
Published: September 2010

A methodology is described for harnessing the power of supercomputer hardware to build an automated modeling system. The problems of applying this new approach to mathematical modeling in geography are discussed by reference to the design of better performing spatial interaction models. It is also possible that the results may provide clues about new theories and knowledge.
Statistical Methods for Evaluating the Geometrical Hierarchy of a Network
Authors: Okabe Atsuyuki , Yomono Hidehiko
Published: September 2010

The objective of this paper is to present statistical methods for evaluating the geometrical hierarchy of a network in comparison with a random hierarchy network. First, the random hierarchy network is explicitly formulated by four stochastic processes in which line segments or lines, which represent roads, are randomly placed and their placement is independent of their ranks. Second, under these stochastic processes, this paper derives the expected value and variance of i) the number of intersections between roads of different ranks; and ii) the distance from an arbitrary point to the nearest highest‐ranked road through two kinds of routes. Using these expected values, the intersection index and the detour index are proposed, and it is shown that these indicators are useful for evaluating the geometrical hierarchy of a network. As calculation of these indices is laborious, an efficient computational method is developed, and its application to an actual example is described.
Periodicity and Market Interactions
Authors: Baker Robert G. V.
Published: September 2010

This paper develops two systems of modeling periodic shopping behavior. The first approach uses a system of Volterra equations to define interactions between populations of consumers and firms in a special market. The second approach develops the relationship between trip length, frequency, and time for consumers in the context of the place utility model. The final section investigates ways of integrating the two approaches.
Fitting Constrained Poisson Regression Models to Interurban Migration Flows
Authors: Flowerdew Robin , Lovett Andrew
Published: September 2010

This paper demonstrates the effects of fitting singly and doubly constrained spatial interaction models using the Poisson regression approach. A large data set containing migration flows between labor market areas in Great Britain in 1970–71 is used. The results of fitting unconstrained, singly constrained, and doubly constrained models are compared with respect to goodness of fit and the interpretability of parameter estimates. The addition of other explanatory variables to the model is also explored.
Location‐Allocation Models of Some Traffic Facilities
Authors: Ohsawa Yoshiaki
Published: September 2010

The objective of this paper is to formulate location‐allocation models of linear facilities, such as bridges, railroad crossings, and staircases. The location‐allocation models in this paper differ from existing location‐allocation models in that the service provided by the facilities is consumed by trips, with associated origins and destinations. The first part of the paper shows the formulation of these location‐allocation problems in one‐dimensional space. It is demonstrated that these problems can also be formulated by the use of a rectilinear Voronoi diagram in two‐dimensional space. The second part of the paper demonstrates fundamental relationships between the number of facilities and the total length of indirect trips and between the number of facilities and the total number of indirect trips for uniformly and independently distributed origins and destinations.
A Location‐Allocation Model of Lösch's Central Place Theory: Testing on a Uniform Lattice Network
Authors: Kuby Michael
Published: September 2010

This paper develops a location‐allocation model of Lösch's central place theory that maximizes the number of firms that can coexist in the market, subject to range, threshold, hierarchy, and other constraints. F.o.b. costs, economies of scale, and elastic demand are included. Consumer behavior postulates concerning the “nearest center hypothesis” and the “indifference principle” are formulated as nonlinear constraints but not used during solution. Methods are developed for simulating the continuous, infinite plain with a discrete, bounded network by use of an outer overflow network and a symmetrical market area constraint. The model is tested by applying it to a uniform lattice network and comparing the results to the expected pattern of nested hexagons. Solutions consistent with the k = 3, 4, and 7 patterns are generated by changing threshold values. However, remaining inconsistencies appear to be due to the inability to express the consumer behavior laws as linear constraints, to the bounded and discrete nature of the network, and to the objective function being the sum of integer variables. The long‐run purpose of developing and validating a location‐allocation model of a location theory is to use it to relax the theory's restrictive assumptions and to apply the theory to nonuniform regions.
Unpacking Central Place Geometry I: Single Level Theoretical k Systems
Authors: Church Richard L. , Bell Thomas L.
Published: September 2010

This paper examines the spatial and potential economic consequences of relaxing the geometrical packing requirement of classical central place theory. Diagrams are used to demonstrate that geometric packing is not necessary to satisfy demand at all discrete points at a given hierarchical level. With unpacked landscapes the same population can be served from fewer, more widely spaced, central places without increasing the length of journey to shop. Consumers have fewer choices in an unpacked landscape, but economies of scale may increase the array of consumer goods and services available.

Relaxing the packing requirement allows the development of a range of stable k systems (i.e., further market entry is disallowed). Between the limits of the k = 3 system (Christaller's marketing principle) and the k = 7 system (the sociopolitical or administrative principle), a range of unpacked k systems can develop including a k = 5 and a k = 6 system. Noninteger k systems are also possible as are systems which are stable mixtures of coexisting k principles. In certain instances, it is economically advantageous for two or more entrepreneurs to co‐locate in the same central place rather than attempting monopolistic control over a more limited hinterland. Such a result is consistent with both Berry and Garrison's concept of the duplication ratio and with recent trends in retail location.
Simultaneous‐Equation Systems Involving Binary Choice Variables
Authors: van Wissen Leo J. , Golob Thomas F.
Published: September 2010

Simultaneous‐equation systems of continuous variables are well known in the social sciences. Unfortunately, these methods cannot be used when dealing with discrete endogenous variables. Although for discrete types of data a broad range of methods and techniques have been developed, their applicability is restricted to single‐equation systems (for example, logit or probit formulations) or to association‐type models (log‐linear models), mainly because of the lack of suitable estimation methods and computer programs. The basic problem is the multivariate error structure of the endogenous variables. This paper presents a simultaneous‐equation system of binary endogenous variables. The model is applied empirically to longitudinal data on mode choice and is compared with the well‐known log‐linear model.
A Dynamic Analysis of Interaction Data: U.S. Rail Freight Flows, 1972‐81
Authors: Knudsen Daniel C.
Published: September 2010

The purpose of this paper is to extend Poisson regression to the analysis of spatial interactions over time. The methodology involves derivation of models using information methods and calibration using Poisson regression. Poisson regression is then used to analyze interannual variation in U.S. rail freight flows, 1972‐81. Findings indicate that import and export variability is less important than is flow variability. Import and export variability is highest for the northeastern United States, but flow variability is highest for the southern and western United States. This has implications for the specification of dynamic models of commodity flow.
A Minimal Representation for Dead‐Reckoning Navigation: Updating the Homing Vector
Authors: Fujita Naofumi , Loomis Jack M. , Klatzky Roberta L. , Golledge Reginald G.
Published: September 2010

A number of organisms are capable of traveling directly back to the origin of locomotion after following a circuitous outbound path, using dead‐reckoning navigation. We describe a minimal representation that could be used for such navigation. It involves keeping track of only the polar coordinates of the origin of locomotion with respect to the observer's current location. An exact solution is provided first, followed by a simplified solution, then a solution involving linearization of trigonometric functions. The paper also examines performance attainable with these solutions and briefly considers ways in which the model might be modified to account for human navigation without reference to landmarks.
The Pace of Indian Urbanization
Authors: Shukla Vibhooti , Berry Brian J. L.
Published: September 2010

In contrast with conventional formulations of urban growth, Tolley proposed a simple, supply‐driven model relying upon the intersectoral differential in nonlabor productivity growth as the prime motivator of urbanization in developing countries. In the present paper, we apply Tolley's model to India over the period 1951–1981 and attempt to explain its mixed performance in tracking the pace of urbanization in that country. A modified version, adjusted for inter‐regional migration, is then simulated for individual Indian states; the exercise confirms actual urban growth during 1971–81 to have been generally below that predicted by Tolley's model. Tolley's assumptions then are tested through an examination of the relationship between urban growth rates and translog indexes of intertemporal productivity growth. Finally, exploratory analysis of Tolley‐model deviations in the various states is used to suggest directions for extending urban growth formulations for India. We conclude with a normative examination of policy implications.
Guests Who Stay
Authors: Schaeffer Peter V.
Published: September 2010

This paper presents a model of legal international labor migration, particularly temporary migration. It explores the likelihood of voluntary return of a majority of foreign workers to their home countries. The approach chosen is that of deterministic simulation. The results of the simulation suggest that a relatively quick labor turnover as required for a true guestworker system is unlikely under most conditions.
Estimating a Destination‐Choice Model from a Choice‐based Sample with Limited Information
Authors: Thill Jean‐Claude , Horowitz Joel L.
Published: September 2010

In most applications of multinomial logit and other probabilistic discrete‐choice models, the estimation data set is either a simple random sample of the population of interest or an exogenously stratified sample. Often, however, it is cheaper and easier to sample individuals while they are carrying out the chosen activity of concern. This produces a choice‐based sample, which presents important problems of estimation and inference. This paper is concerned with estimation of destination‐choice models from choice‐based samples when neither the aggregate market shares of alternatives nor the probability distribution of explanatory variables in the population is known. The method of Cosslett (1981) for estimating multinomial logit models from such data is summarized, and the limitations on information about choice behavior that can be recovered from the sample are explained. An empirical model of pharmacy choice in the Namur, Belgium, area is presented. It is shown that useful and important information about destination‐choice behavior can be obtained from a choice‐based sample, even without knowledge of aggregate market shares and the probability distribution of explanatory variables.
The Human Role in Earth Surface Systems: Some Theoretical Considerations
Authors: Phillips Jonathan D.
Published: September 2010

Studies of human influences on the environment may treat human agency as an imposed, exogenous source of change or disturbance, or as an intrinsic part of earth surface systems. Consideration of human influences as exogenous or endogenous to earth surface systems can affect, or even predetermine, the outcome of analyses. This is demonstrated via qualitative stability analyses of generalized mass‐and‐energy‐flux systems. When human impacts are considered as external disturbances such systems are stable, and will regain equilibrium after changes or perturbations. Conversely, when human impacts are included as a system component, with goals of either maximizing or minimizing throughput of mass and energy, the system is inherently unstable.
Interregional Migration Modeling via Entropy and Information Theory
Authors: Roy John , Flood Joe
Published: September 2010

In attempting to model gross migration flows, as distinct from net flows, entropy and information theory models supplement those from the demographic tradition. However, clear differences exist between these two classes, including the type of origin and destination information which needs to be supplied, the relationship between the overall decision to migrate and the conditional choice of destination, the role of behavioral variables other than distance, and the expected predictive performance. In this paper, an enhanced interregional migration model is introduced which attempts a further integration of both the above classes. A linear version of the model is used for exploratory data analysis on a large Australian population census data set. Several alternative hypotheses are then tested with the general model. Some guidelines are also indicated toward developing a fully dynamic version of the model as well as a formal hierarchical framework.