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

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

TEMPORAL and SPATIAL VARIABILITY OF CANADIAN INVENTIVE COMPANIES and THEIR INVENTIONS: AN ISSUE OF OWNERSHIP

Inventing is an important prerequisite for industrial economies to remain technologically competitive. Yet it is not well known how inventive companies of domestic or foreign ownership can affect a nation's technological base and, ultimately, its spatial-economic system. The present study examines this relationship in Canada by investigating the performance of its indigenous and foreign-owned inventive companies at the national, subnational, and urban levels. The results indicate that: (1) Canada's indigenous inventive companies are distinct from their foreign-owned counterparts in that they are generally smaller, are more apt to have teams of inventors, are more likely to develop product inventions, have come to manage a greater share of this nation's inventions, and are increasing their role in key Canadian industries; and (2) geographically, Canada's two largest cities and its core region were adversely affected by the declining inventiveness of American-controlled companies during the 1980s. L'esprit ?invention est une nécessité pour que les économies industrielles restent en conditions de concurrence technologique. Cependant, on connaît très peu de la manière que les entreprises inventives de propriété domestique ou étrangère affectent la base technologique ?un pays et, enfin, affectent son système spatio-écono-mique. La présente étude considère ces rapports au Canada au niveau national, sous-national et local, en exminant les performances des entreprises inventives indigènes et étrangères. Les résultats indiquent (1) qu'au Canada les entreprises indigènes et inventives diffèrent de leurs analogues étrangers: en général elles sont plus petites, ont plus tendance à consister en équipes ?inven-teurs, sont plus susceptibles de développer les inventions produites, produisent une plus grande part des inventions canadiennes, et sont en train ?augmenter leur rôle dans les industries canadiennes; et (2) que le déclin de ?esprit ?invention dans les entreprises dirigées par les américains a affecté défavorablement les deux villes les plus grandes au Canada, ainsi que la partie centrale du pays, pendant les années 1980. Mots-clés: invention, Canada, propriétéétrangère, technologie, produit     

AN ASSESSMENT OF BACK-SCATTERED ELECTRON PETROGRAPHY AS A METHOD FOR DISTINGUISHING MEDITERRANEAN OBSIDIANS

The recent application by Burton and Krinsley (1987) of back-scattered electron (BSE) petrography to obsidians from sources located in the south-western United States established that this method can effectively resolve and characterize included micro-crystalline phases that have proven difficult to analyse by optical thin-section microscopy. In the first extension of their original study, we have examined, using BSE petrography, obsidians from island sources located in the Mediterranean, including sources known to have been exploited in prehistory. Because of the kinetic contrasts on their crystallization, these microcrystalline phases reflect the magmatic history of the obsidian, providing information about superheating, supercooling, sub-solidus processes, and other phenomena. This information is of significance for the chemical analysis of Mediterranean obsidians and also as the basis for a powerful alternative to existing non-destructive analytical methods for the sourcing of archaeological and art-historical obsidian.     

HISPANO-MORESQUE POTTERY PRODUCTION OF THE FOURTEENTH-CENTURY WORKSHOP OF TESTAR DEL MOLÍ (PATERNA,SPAIN)

Excavation of Testar del Molí, the only workshop found in the Manises-Paterna area, revealed the existence of a fourteenth-century ceramic workshop covering the remains of the thirteenth-century workshop. This study is concerned with the fourteenth-century production, and forthcoming papers will connect both epochs following the findings of current excavations. The chemical and mineralogical characterization of the ceramic production of this workshop shows the presence of three groups of ceramic pastes which could also be distinguished by, and, thus, related to, their daily use. The raw materials found in the excavation have also been mineralogically and chemically characterized, and a model of possible mixtures of raw materials has also been developed in order to determine their possible use in the manufacture of the pottery previously characterized.     

MULTICOIN: A TOOL FOR CLASSIFYING COINS IN A MULTIMEDIA ENVIRONMENT

Classifying coins found during excavation is a challenging task for the archaeologist. This paper describes a multimedia system designed to assist the archaeologist by enabling him either to classify coins based on a pre-existing catalogue or to draw up his own catalogue for specific purposes. The system can also be used to train novices in the field: following an initial screening, the archaeologist only has to examine coins specifically requiring his expertise. A case study uses coins minted in Salerno 800–1200 AD, but the system has been designed to classify any set of coins by simply changing the underlying knowledge base. Very little training is required to operate the user-friendly system, which runs on multimedia PCs, as it is written using the C++ language and makes full use of the advanced features of Windows 3.11.     

Ancestral pueblo population aggregation and abandonment in the North American Southwest

After over a century of archaeological research in the American Southwest, questions focusing on population aggregation and abandonment continue to preoccupy much of Pueblo archaeology. This article presents a historical overview of the present range of explanatory approaches to these two processes, with a primary focus on population aggregation in those regions occupied by historic and prehistoric Pueblo peoples. We stress the necessarily complementary nature of most of these explanations of residential abandonment and aggregation. Case studies from the northern Southwest illustrate the continuous nature of these processes across time and space. We suggest that additional explanatory potential will be gained by the use of well-defined theoretical units to frame our current approaches. We extend the use of the local community concept as a theoretical unit of organization that, along with explicit archaeological correlates, should help advance our research into population aggregation and abandonment in this and other regions of the world.     

Human biology in the Classic Maya collapse: Evidence from paleopathology and paleodiet

We review evidence from human biology—paleopathological and isotopic paleodietary studies on ancient Maya skeletons—to assess the validity of ecological models of the Classic Maya collapse, in which elevated disease and deteriorating diet are commonly assumed. To be upheld, the health arguments of ecological models require that the Maya disease burden (1) was greater than that for many other societies and (2) increased over the span of occupation. The dietary argument requires (1) consistent change in diet from Preclassic and Early Classic Periods to the Terminal Classic and (2) increasing social divergence in diet. A correlation between diet and disease is necessary to link these arguments. Neither pathology nor isotopic data consistently support these criteria. Instead, it appears that local environmental and political factors created diversity in both disease burden and diet. In view of the human biological data, we are skeptical of ecological models as generalized explanations for the abandonment of Classic Maya sites in the southern lowlands.