Trucking deregulation and highway safety: The effect of the 1980 Motor Carrier Act

The relationship between deregulation in the trucking industry and highway safety is an important economic and social issue. Analyses thus far have concentrated on the relationship between the downward pressure imposed on freight rates by deregulation and total safety investment by firms. Two issues which have been ignored are the effects that deregulation had on route carriage restrictions and total firm mileage. We show that the inclusion of these factors yields a model in which the relationship between motor carrier deregulation and highway safety is dependent upon the relative effects of all three factors. Estimation of the model using accident data implies that trucking deregulation did not deteriorate highway safety and may have actually improved it.     

Analysis of Austrian stocks: Testing for stability and randomness

This paper is concerned with subjecting two popular assumptions about the behavior of stock market prices to empirical tests: first, the random walk hypothesis developed by Bachelier (1900), Osborne (1959), and Mandelbrot (1963); second, the stable distributions hypothesis by Mandelbrot (1963) and Fama (1965). For this purpose, ten time series from the Vienna Stock Exchange were used. The first hypothesis was tested using both non-parametric and parametric methods. To obtain evidence with regard to the seond hypothesis, a graphical procedure and statistical estimation on the basis of the empirical characteristic function were applied. On analysis of our data, it turned out that, at least for the time period under consideration (1985–1990), severe doubts are cast on the above assumptions.We gratefully acknowledge the help of Peter Mitter, Institute for Advanced Studies, and Franz Köstl, Österreichische Kontrollbank, who provided us with the necessary data, and the comments of the anonymous referees.     

Some comparative-statics results for nonlinear input-output models of a multisectored economy,and related results for nonlinear price-demand relations

For a nonlinear version of the linear input-output model of Leontief, we consider the effect, on the vector x of total gross outputs, of changes in the components of the final-demand vector c. For example, it is shown that, for a certain important class of models, the “large-change elasticity” of any component of x, with respect to any component of c, is less than or equal to unity. Some similar results are proved concerning properties of nonlinear price-demand relations for the case in which all goods are weak gross substitutes. Unlike earlier work in this general area, we do not introduce hypotheses concerning the indecomposability or homogeneity of certain mappings. For that reason, the results are valid for the price-demand relation for a single firm, or for any collection of firms.     

Contrast enhancement of the gastrointestinal tract on MR images using intravenous gadolinium-DTPA

Gadopentetate dimeglumine was administered intravenously to 16 patients undergoing abdominal magnetic resonance (MR) imaging. T1-weighted and fat-suppressed T1-weighted images were acquired before and after intravenous administration of 0.1 mmol/kg gadopentetate dimeglumine. The stomach, small bowel, and colon were analyzed regarding the presence and relative intensity of contrast enhancement. Diffuse enhancement of the gastrointestinal tract wall was observed in all patients following contrast material administration. Such enhancement was most conspicuous on fat-suppressed T1-weighted images. Quantitative measurements indicated that the wall of the gastrointestinal tract enhanced approximately 100% with gadopentetate dimeglumine. This study demonstrates that enhancement of the normal gastrointestinal tract occurs routinely when intravenous gadopentetate dimeglumine is administered, and such enhancement should not be considered indicative of gastrointestinal pathology. Furthermore, it suggests the potential utility for using intravenous rather than orally administered contrast agents to provide enhancement of the gastrointestinal tract on MR images.     

An application of the extended cross impact method to generating scenarios of social change in Japan

Scenarios of Japanese society in 2000 are obtained by applying an extended correlational cross impact analysis. Since the scope of the scenarios is extensive, a procedure is developed to generate the scenarios that consists of a preprocessing of the events of interest and a step-by-step application of a cross impact method. Three scenarios are described, based on a workshop where the procedure was applied.     

THE VALUE OF CLEANER AIR: AN INTEGRATED APPROACH

Policymakers in the legislative and regulatory arenas face increasing public expectations that authorities will both promulgate and implement strict environmental programs. At the same time, the aggregate cost of such programs is rising and is impacting economic sectors previously untouched. In this context, a major study used an integrated interdisciplinary perspective to determine what economic benefits would result from air pollution controls. Specifically, the study developed estimates for the health benefits of reducing ozone and fine particulate matter concentrations in the nation's most polluted region—the South Coast Air Basin centering on Los Angeles. This paper presents the economic methodologies and results of that study. It also discusses how health and atmospheric sciences informed the economic assessment.     

Optimale Aufteilung des Stichprobenumfangs bei mehreren Merkmalen

Zusammenfassung Es wird gezeigt, daß sich das vonNeyman undTschuprow für ein einziges Merkmal gelöste Problem der optimalen Aufteilung des Stichprobenumfangs auf vorgegebene Schichten auf ein nichtlineares Programm mit linearen Restriktionen und nichtlinearer Zielfunktion zurückführen läßt. Auf Grund der Konvexitätseigenschaft der Zielfunktion ergibt sich, daß das Minimum der Zielfunktion (Minimum der Streuung des Stichprobenmittels ) stets eindeutig ist. Der beiNeyman undTschuprow mögliche Fall, daß sich in derh-ten Schicht ein Stichprobenumfang ergibt, der größer als der Umfang in der Gesamtheit ist, kann hier nicht auftreten.Durch Einführung einer verallgemeinerten Streuung wird das Problem der optimalen Aufteilung bei vorgegebener Schichtung imk-dimensionalen Merkmalsraum aufk Merkmale verallgemeinert. Es wird gezeigt, daß diese verallgemeinerte Streuung (=Zielfunktion eines nichtlinearen Programms) im allgemeinen nicht über dem ganzen konvexen Bereich der zulässigen Lösungen konvex (von unten) ist. Ein Teilbereich des zulässigen Bereichs, über dem die Zielfunktion konvex ist, wird angegeben. Schließlich werden hierzu vergleichende Ergebnisse gebracht.