MEASURING THE DISPERSAL OF SUBSIDIZED HOUSING IN THREE CITIES

This paper uses the Index of Dissimilarity to measure the degree of dispersal of subsidized housing between 1970 and 1980 in three cities—Chicago, Baltimore, and St. Louis. The data show that subsidized housing has been dispersed in each of the cities, in accordance with federal housing policies of the late 1960s and 1970s. There are differences among the cities, however, in the degree of dispersal and the size of the subsidized housing inventories. The data also show that subsidized housing has been extended to predominantly white census tracts and tracts with incomes higher than the city-wide median incomes. These white, higher-income tracts have lower densities of subsidized housing than poorer tracts with large black populations.     

A Theory of the Early Growth of the Firm

Economic enterprise consists in the matching of resources andopportunities to create value. Growth processes of the new enterpriseare here explored in a systems model inspired by Penrose. Asequence of phases in the early life of the firm reflects growthprocesses and problems, solutions giving rise to new problems.Firms must access, mobilize and deploy resources before theycan generate resources for growth. Subsequent phases—inwhich growth reinforcement and growth reversal forces contend—arenot universal, but are set in motion in an important minorityof firms, the major job creators. Beyond the early phases, criticalproblems facing the firm are more diverse. The growth of thefirm is related to the building of the competence needed torespond to changing industrial opportunities.     

AUTONOMOUS EXPLORATION AND CONTROL OF CHAOTIC SYSTEMS

Control algorithms that exploit chaotic behavior can vastly improve the performance of many practical and useful systems. Phase-locked loops, for example, are normally designed using linearization. The approximations thus introduced lead to lock and capture range limits. Design techniques that are equipped to exploit the real nonlinear nature of the device loosen these limitations. The program Perfect Moment is built around a collection of such techniques. Given a differential equation and two points in the system's state space, it automatically selects and maps the region of interest, chooses a set of trajectory segments from the maps, uses them to construct a composite path between the points, and causes the system to follow that path via appropriate parameter changes at the segment junctions. Rules embodying theorems and definitions from nonlinear dynamics are used to limit complexity by focusing the mapping and search on the areas of interest. Even so, these processes are computationally intensive. However, the sensitivity of a chaotic system's state-space topology to the parameters of its equations and the sensitivity of the paths of its trajectories to the initial conditions make this approach rewarding in spite of its computational demands. Controlled trajectories found by this program exhibit a variety of interesting and useful properties. For example, detours through chaotic regions can be used to steer trajectories across boundaries of basins of attraction, effectively altering both the geometry of and convergence properties within a particular convergence region, such as the capture range of a phase-locked loop circuit.     

Effect of Modified Atmosphere Storage on C. Botulinum Toxigenesis and the Spoilage Microflora of Salmon Fillets

Modified atmosphere (MA) storage in conjunction with refrigeration has been shown to significantly increase the shelf life of fresh fish and other products, but the effects, if any on the outgrowth and toxigenesis of C. botulinum are unknown. A commercial system was duplicated in the laboratory and the effects of modified atmosphere on the outgrowth of C. botulinum types A, B, and E were observed in inoculated salmon fillets and sandwiches stored at 4.4°C and 22.2°C. Inoculated samples stored in air at the same temperatures were used as controls. No toxigensis was observed in either the air or modified samples stored at 4.4°C, but all inoculated samples held at 22.2°C were toxic within 2–3 days. Spoilage generally preceded toxigenesis. In a concurrent study, the tendency of CO₂ environments to repress the growth of gram negative bacteria to a greater extent than gram positive bacteria was also noted.     

Factors Related to Potato Mealiness

Four potato cultivars from 1984 and 1985 growing seasons were studied. Specific gravity did not correlate with potato size or shear strength, nor could it be used to predict sensory mealiness scores. Shear strength measures of the cooked potatoes showed that the Russet Burbank had a particularly strong structure at low deformations. Starches from the two more mealy cultivars, Russet Burbank and Norchip, had slightly lower gelatinization temperatures than those from the two waxy cultivars, Pontiac and LaSoda. Gelatinization temperatures were higher in potato juices than in water. Starches from the two mealy cultivars gave swelling powers between those of the two waxy cultivars, but yielded higher solubles. Pontiac potato starch exhibited anomalous behavior in its resistance to swelling and in development of viscosity in the amylograph.     

DETERMINATION OF THE YIELD STRESS OF HYDROCOLLOID DISPERSIONS

The yield stresses of dispersions of guar gum (0.5–2.0% by weight) and gelatinized cornstarch (2.5–5.0% by weight) were measured using several different established experimental methods. The yield stresses in these polysaccharide dispersions result from intermolecular hydrogen bonding and molecular entanglements, thus the higher yield stress and hysteresis effect in guar gum dispersion was interpreted in terms of the greater hydrogen-bonding density and molecular entanglements caused by the more extended chain conformation. The results confirm that there is no one absolute value for the yield stress of the hydrocolloid dispersions and that the viscoelastic characteristics of the test materials influence the shear rate and time dependence of yield stress. Therefore, experimental determination of yield stress must be made relevant to the practical application.     

RETHINKING THE POLITICS OF DOWNTOWN DEVELOPMENT

ABSTRACT: In the political science literature, downtown redevelopment has long been seen as the project of a region's economic elites. But in recent years, large corporations, banks, and department stores have in many cases abandoned central business districts, and downtowns are now more likely to be developed as centers of entertainment and culture, or as residential districts. This article posits that changing downtown land uses are accompanied by changes in the downtown influence structure, with nonprofit sector and real estate industry leaders now dominating downtown business organizations.