Network Access Pricing and Deregulation

The paper addresses the question of pricing access to the networkfacilities of an incumbent firm after deregulation. Networkaccess pricing continues to be regulated in such industriesas telecommunications, railroads, eletric power and naturalgas. We emphasize that access prices should be set such thatthey satisfy an individual rationality condition for the incumbentfirm so that access is granted voluntarily. We examine the effectsof the voluntary access condition incentives for entry and showthat properly chosen access prices incentives for efficiententry using several alternative competition models: Bertrand–Nash,Cournot–Nash and competition Chamberlin with differentiatedproducts.     

THE FUTURE CENTRAL CITY: GENTRIFIED OR ABANDONED?*

Displacement of minorities and low income individuals has been reported in the popular press and in a number of scholarly case studies. Whether displacement is a major national problem or limited to a number of isolated neighborhoods is the subject of national debate. Urban scholars point to decreasing overall demand for central city properties and an overall decrease in the number of white individuals living in the central city to discount the significance of the reports of displacement. This article analyzes both migration by race and housing trends in central cities. The analysis proceeds from nationally aggregated data to central city level and census tract level data. The argument is made that while the population is decreasing in central cities, the number of middle class individuals is increasing in many central city neighborhoods and the number of available housing units is decreasing. This is increasing the competition for existing units. If these trends continue and overall housing costs continue to increase, displacement is likely to become widespread.     

Computer Simulations of R-Curve Behavior in Microcracking Materials

A computer program has been developed which simulates the process of microcracking in two-phase ceramic materials. This simulation provides a method of examining the complex interactions which occur between a propagating crack and the residually stressed particles around it. As the residual stresses near second-phase inclusions are relieved by microcrack formation, a process zone forms around the main crack, partially shielding it. The resulting crack resistance curves, or R curves, associated with crack shielding mechanisms are generated by the program. Three variables— the microcrack density (f_s), the dilatant strain associated with each microcracked particle (θ), and the orientation of the microcracks (Ψ)— were used to determine their influence on fracture toughness. The steady-state toughness was found to increase with second-phase particle additions, increased dilatant strain, and the formation of microcracks parallel to the direction of applied stress. However, the magnitude of toughening increase attained in these-simulations was generally lower than that predicted by continuum models. This discrepancy is attributed to the fact that interactions between microcracks produce frontal zones which result in a positive Δk , and hence, a lower steady-state toughness. This behavior is enhanced when microcracks link with the main crack to promote further extension.     

Quantitative Analysis of Carotenoids and Carotenoid Esters in Fruits by HPLC: Red Bell Peppers

The carotenoids of red bell peppers were analyzed without saponifi-cation by high performance liquid chromatography using octadecyl silica as stationary and methanol-ethyl acetate as mobile phases. The red bell peppers contained 280 ug/gm total carotenoids. Capsanthin accounted for 60% of the total carotenoids. Also present were 11%beta-carotene and 20% capsorubin. Capsanthin was acylated with C₁₂ to C₁₈ saturated fatty acids.     

Further Studies on the Formation of Nitrosamines in Cured Pork Products Packaged in Elastic Rubber Nettings

Traces of N-nitrosodi-n-butylamine (NDBA) and N-nitrosodiethylamine (NDEA) can form in cured pork products packaged in elastic rubber nettings due to the interaction of nitrite in meat and amines in the rubber. Studies were carried out to determine whether taking nettings off immediately after processing or placing a layer of collagen as a barrier between nettings and meat could prevent or minimize formation of the above nitrosamines. None was effective. However, cured pork products packaged in a reformulated rubber netting, made with different amine additives, contained either none or only negligible levels of NDBA or NDEA, but, instead, contained 8–104 ppb levels of a new nitrosamine, N-nitrosodibenzylamine which is reported to be noncarcinogenic.     

Evaluation of characterization methods for thin sections of silver halide microcrystals by analytical electron microscopy

Silver halide microcrystals are usually composed of different phases with varying halide compositions. These microcrystals can be sectioned with an ultramicrotome with a certain thickness in a specific direction. The scanning electron microscopical analysis of these sections provides information on the internal halide profile.
During sample sectioning, many deformations can be induced in the material, and usually dominate the different scanning electron images.
By acquiring X-ray maps, it is possible to locate the different phases in the sections. This technique, however, is very time-consuming, and can only be used when the local halide variations are very high.
When an EDX line scan is acquired over the section, information on the position of the phases with different halide composition is obtained in a reasonable time, and shows no dependence on the section deformations. From this knowledge, several positions on the section are selected where local X-ray analyses are performed. After quantifying the results, the internal halide distribution is obtained. The analytical lateral resolution is about 30 nm for sections ≈100 nm thick.