The structural and economic implications of urbanization

"This study surveys the policy issues associated with urbanization following the abolition of the pass laws [in South Africa]. The demographic background is briefly sketched. Using neo-classical analysis as a starting point, particular attention is paid to the present inefficiencies of city form associated with segregation. It is argued that current planning procedures are in danger of perpetuating or even worsening the situation. Obstacles to employment generation are considered and transport, local government and housing issues are discussed. On every front, urbanization policy is unstable and, even in the short term, there will be pressures to change it."     

Projecting the future size and health status of the U.S. elderly population

"A projection model based on a multivariate continuous state, stochastic process is presented. The model allows multiple time-varying covariates to be used so parameters can be estimated from time series information on health changes and mortality, and their interaction. Health changes are simulated by altering parameters controlling the age trajectory and diffusion of risk factor means, variances, and covariances....By increasing the information used in projections it may be possible to better (a) anticipate the state of health at extreme ages, (b) forecast changes in health at specific ages over time, (c) stimulate the effects of specific interventions, and (d) determine the sensitivity of outcomes to a range of interventions."     

Purchasing practices in a hospital environment: an ethical analysis

The critical state of the hospital industry, as previously described, generates a difficult decision environment for the materiel manager and those in the purchasing function. The unique life- and death circumstances of hospitals impose a further onus on those who manage them. In the name of saving lives, they can find a convenient excuse to disregard all moral principles, forgetting the Socratic dictum "it is not enough that one lives, but that one lives well." Without the moral "right stuff," they can easily give in to the seductions of momentary gains and glory through ethical short-cuts. There is wisdom and consolation in the words that "nice guys may appear to finish last, but usually they're running in a different race." Studies have established a direct relationship between corporate excellence and ethical values. The reality of competition in the hospital industry dictates that the integration of ethics into the life of the organization should happen by design and not by accident. This is what is meant by strategy. If hospitals would strive for excellence to survive and grow, they should have a strategy with a mission statement that also embodies its moral values and moral agenda. Such an approach does not guarantee that an organization will become immune to moral contamination, but it does provide an antidote.     

Body support testing and rating

The REF, C, and score are a means to give quantitative values for product performance. Other product variables defined as humidity control factor, shear control factor, differential temperature control factor, product life factor, and cost factor were not addressed as part of this study. Additional variables include delivery, maintenance, and warranties. These components can be added to the score in some weighted manner as they become clinically founded. Interface pressures and shears were not measured for beds that are gatched. Each product tested will have characteristics pertinent to its own design that must be addressed to minimize sacral and coccyx skin breakdown when subjects are in this posture because some pneumatic pads bottom out to give excessive sacral and coccyx pressure while others wrinkle when used in this position. This is of major concern when one considers that the coccyx is more susceptible to pressure than any other bony prominence. There may be some aversion to labeling support product performance because it will allow the purchaser to know what is being bought. This initial study indicates the feasibility of quantitating what all patients require: a valid interface support surface for each specific need. The user can be adequately informed before the purchase as to a product's merits without being influenced by the results of inadequate testing, referrals, or sales media influences. Although cushions, shoes, or other prosthetic/orthotic devices were not part of this study, it is appropriate to rate all these devices in a similar manner by simply comparing pressure relief attained to that desired, expressing the result as a percentage of the worst case, and then labeling the product accordingly. Those subjects with sensation can rate comfort as part of the overall score. For cushions, ischial tuberosity pressure relief can be expressed as a percentage of the maximum attainable relief. Metatarsal head relief during gait as well as during static testing can be measured, and claims can be made for shoes and sneakers. Where impact loads and shear forces are paramount, the score must comprise appropriate parameters. Similarly, amputee distal stump relief as a percentage of worst case could be specified by the fitter. Iliac crest relief as a percentage of worst case can also be specified by the fitter. In all instances the score is not a subjective rating but one that can be measured correctly. All body support products can be given an REF, C value, and score as well as other qualifying values where appropriate instrumentation and sufficient subject sampling is used.     

Integration in the mortgage market

The deregulatory trend and advances in technology during the 1980s removed many restrictions on the ability of U.S. depository financial institutions to obtain and redistribute funds across diverse geographical markets. This pervasive deregulation and innovation should have increased the degree of integration between different geographical financial markets. Yet there is little empirical evidence available on the validity of this expectation. It is important to provide such evidence since much of the U.S. depository institution regulatory policy is predicated on the assumption of highly localized, segmented financial markets. Considering alternative breakpoints at 1980 (DIDMCA) and at 1982 (Garn-St Germain), the current study tests the hypothesis that the degree of geographical financial integration after this period exceeded that prior to this period. Mortgage markets are focused on due to their historical importance in the regulation of funds flows. The study finds a significant increase in the mean contemporaneous correlation among FHLB districts' mortagage rate residuals in a vector-autoregressive system between two test periods. Further analysis shows that the distance between FHLB districts' headquarters and their respective pairwise interdistrict correlation coefficients are negatively related in the prior period but not significantly related in the later period. Economic booms and busts alternated among the districts over the two sample periods in a manner consistent with the reallocation of capital among more integrated financial markets. Individual districts' mortgage rates have been more sensitive to variations in national credit market conditions since deregulation was legally recognized by DIDMCA in 1980. Thus, the collective empirical evidence found in this study indicates that mortgage markets have responded to deregulation and marked technological advances by moving toward a national, highly integrated market. Regulators' preoccupation with highly localized, segmented markets must consequently be reexamined.     

A development model of developing economies with capital and knowledge accumulation

This study suggests a model of economic development which treats knowledge accumulation as an endogenous variable. It examines possible dynamic processes in an economic system which accumulates knowledge from developed nations. We describe the dynamics of the system by the interactions of three variables—economic conditions, level of knowledge, and openness. The introduction of openness as an important endogenous variable is due to the fact that the development model considered here is primarily concerned with the economic dynamics of the People's Republic of China. We are especially interested in nonlinear phenomena such as catastrophes and limit cycles. We show that small shifts in political policies may result in great social structural changes.The author is very grateful to two anonymous referees for important comments and to an anonymous referee for linguistic help.     

The aggregated excess demand function and other aggregation procedures

Summary Two theorems are given; the first extends the Sonnenschein-Mantel-Debreu theorem characterizing aggregate demand functions from the set ofn2 commodities to all of the 2 ⁿ –(n+1) subsets of two or more commodities. The second theorem concerns spatial voting models for k2 candidates over a space of n2 issues. The theorem characterizes the sincere elecion rankings of thek candidates over all of the 2 ⁿ –1 subsets of one or more issues. Both theorems have the same kind of conclusion; anything can happen. By demonstrating the mathematical reasons for these conclusions and by recalling related, recent results from statistics, voting, and economics, it is argued that this anything can happen conclusion is the type one must anticipate for aggregation procedures; particularly for the processes commonly used in economic models where the procedure is responsive to changes in agents' preferences, changes in data, etc.I am pleased to acknowledge conversations with L. Hurwicz, A. Mas-Colell and C. Simon about this material. In particular, I want to thank J. Jordan for his several helpful suggestions. Also, I benefited from comments made at meetings and seminars where these results were presented; this includes a June, 1990, conference in Stockholm, Sweden. Some stylistic suggestions were made by Arvid and Padon Kalinen. This research was supported, in part, by NSF Grant IRI-8803505.     

An appreciation of our referees

Editorial

An appreciation of our referees     

Operational Research and the environment

The discipline of Operational Research (OR) is primarily concerned with improving the effectiveness and efficiency of decision processes. These processes take place everywhere in society: industry, banking, agriculture, government, politics. Frequent use of mathematical optimization models is typical of OR. Since the early '80s these models are increasingly packaged in a user-friendly way, as Decision Support Systems. In the following we will illustrate how OR can be used to describe and solve a number of environmental problems.     

On modeling incentive systems which utilize pollution charges for pollution abatement

This paper examines a scheme of economic incentives for environmental protection, in which spatially differentiated pollution taxes are in use in compensating the pollution abatement costs. A simple mathematical model is described which determines an incentive system that encourages polluters to reduce the discharges to an acceptable level of ambient quality standards in a cost-effective manner. It is shown that the vector of pollution charges has to be proportional to the marginal abatement cost vector, but is smaller than the latter in magnitude. It is demonstrated that a necessary incentive effect may be achieved even if the total pollution charge is much lower (about three times) than the total abatement costs. It is also estimated how this charge incentive system reconciles conflicting criteria of cost-effectiveness and of equity. These conclusions are verified by numerical experiments with real data.