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.     

U.S. Savings Bonds: the planned-gift forgotten asset

As older Americans take a close look at their assets, promote their interest in unlocking the wealth accumulation in their U.S. Saving Bond holdings. Use careful planning and advice when promoting this gift strategy.     

Household formation by the young in the United States

"A model of household formation by the young is specified and estimated. It was found that the headship rate for the young in the United States depends on income, the cost of housing, the number of families receiving AFDC payments, the age at first marriage for females and for males, and the percentage of males enrolled in college. Household formation by the young is much more sensitive to changes in income and the price of housing than household formation by the entire adult population. The estimated results are used to examine the change in the headship rate from 1961 to 1979 and from 1979 to 1987."     

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