Measuring the Contribution of Public Infrastructure Capital in Sweden

Our purpose in this paper is to examine how one might evaluate and measure the contribution of public infrastructure capital on private sector output and productivity growth in Sweden. We do this by specifying and implementing empirically a number of alternative econometric models, using annual data for Sweden from 1960 to 1988. Using a dual cost function approach, we find that increases in public infrastructure capital, ceteris paribus, reduce private sector costs. We compute that amount of public infrastructure capital that would rationalize the cost savings incurred by the private business and manufacturing sectors, and find that the amount that can be rationalized in this manner is less than what was in fact available in 1988, but that the extent of excess public infrastructure capital has been falling in the 1980's.

Price Indexes for Microcomputers: An Exploratory Study

In this paper we focus on alternative procedures for calculating and interpreting quality-adjusted price indexes for microcomputers, based on a variety of estimated hedonic price equations. Our data set comprises an unbalanced panel for 1265 model observations from 1982 to 1988, and includes both list and discount prices. We develop and implement empirically a specification test for selecting preferable hedonic price equations, and consider in detail the alternative interpretations of dummy variable coefficients having time and age, vintage and age, and all of the time, age, and vintage dummy variables as regressors. We then calculate a variety of quality-adjusted price indexes; for the Divisja indexes we employ estimated hedonic price equations to predict prices of unobserved models (pre-entry and post-exit). Although our indexes show a modest amount of variation, we find that on average over the 1982-88 time period in the US, quality-adjusted real prices for microcomputers decline at about 28% per year.

Performance of thermal barrier coatings in high heat flux environments

Thermal barrier coatings were exposed to the high temperature and high heat flux produced by a 30 kW plasma torch. Analysis of the specimen heating rates indicates that the temperature drop across the thickness of the 0.038 cm ceramic layer was about 1100 C after 0.5 sec in the flame. An as-sprayed ZrO2-8%Y2O3 specimens survived 3000 of the 0.5 sec cycles with failing. Surface spalling was observed when 2.5 sec cycles were employed but this was attributed to uneven heating caused by surface roughness. This surface spalling was prevented by smoothing the surface with silicon carbide paper or by laser glazing. A coated specimen with no surface modification but which was heat treated in argon also did not surface spall. Heat treatment in air led to spalling in as early as 2 cycle from heating stresses. Failures at edges were investigated and shown to be a minor source of concern. Ceramic coatings formed from ZrO2-12%Y2O3 or ZrO2-20%Y2O3 were shown to be unsuited for use under the high heat flux conditions of this study

Quantized Conductance of a Single Magnetic Atom

A single Co atom adsorbed on Cu(111) or on ferromagnetic Co islands is contacted with non-magnetic W or ferromagnetic Ni tips in a scanning tunneling microscope. When the Co atom bridges two non-magnetic electrodes conductances of 2e^2/h are found. With two ferromagnetic electrodes a conductance of e^2/h is observed which may indicate fully spin-polarized transport.Comment: 3 pages, 2 figure

Costs, Institutional Mobility Barriers, and Market Structure: Advertising Agencies as Multiproduct Firms

What accounts for the diversity and limited concentration that has long characterized the organization of the advertising agency industry? This question is addressed by treating an advertising agency as a multiproduct firm. The firm's product line or service mix is defined in terms of the set of different media categories where an agency places the advertising messages which it creates on behalf of its clients. Evidence is presented indicating that the structure of demand and costs in the advertising agency industry conforms to the conditions that MacDonald and Slivinski (1987) showed were required for an industry to sustain an equilibrium with diversified firms. Building on this framework, we formulate a set of three hypotheses relating to the realization of product-specific scale and scope economies. The first two hypotheses posit that given low fixed costs and minimal entry barriers, both media-specific scale and scope economies are available and can be exploited by relatively small-size agencies. The third hypothesis suggests that large agencies may experience diseconomies of scope as a consequence of excessive diversification induced by two pervasive industry institutional phenomena: (i) 'bundling' of agency services to match client demand for a mix of media advertising; and (ii) 'conflict policy' which prohibits an agency from serving competing accounts and operates as a mobility constraint. Utilizing a multiproduct cost function, we estimate media-specific scale and scope economies for a cross-section of 401 U.S. agencies in 1987. The results obtained support the set of three hypotheses outlined above.