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Light and Electron Microscope Study of the Morphological Changes in L 929 Cells and Human Periodontal Ligament Fibroblasts Exposed to Toxic Dental Material.
A Brief History of Affordable Housing Cooperatives in the United States
For over 75 years housing cooperatives have been a source of affordable housing. Currently, the 376,000 dwelling units of affordable cooperatives is equivalent to seventeen percent of the rent reduction units owned by publichousing authorities. Understanding that affordable cooperatives have been developed under varying historical circumstances provides insights on how they could play a role in the future supply of affordable housing. The history of affordable co-ops starts during the 1920s and after World War II with the ethnic, union, and New York government financed co-ops. Through the 1960s and the early 1970s cooperatives were financed by various federal direct assistance programs. Since the late 1970s co-ops have been sponsored by nonprofit organizations and by federal and municipal government privatization programs. A workable institutional structure for affordable cooperatives has developed as a result of this historical evolution
Sequential Pre-Marital Investment Games: Implications for Unemployment
Agents on the same side of a two-sided matching market (such as the marriage or labor market) compete with each other by making self-enhancing investments to improve their worth in the eyes of potential partners. Because these expenditures generally occur prior to matching, this activity has come to be known in recent literature (Peters, 2007) as pre-marital investment. This paper builds on that literature by considering the case of sequential pre-marital investment, analyzing a matching game in which one side of the market invests first, followed by the other. Interpreting the first group of agents as workers and the other group as firms, the paper provides a new perspective on the incentive structure that is inherent in labor markets. It also demonstrates that a positive rate of unemployment can exist even in the absence of matching frictions. Policy implications follow, as the prevailing set of equilibria can be altered by restricting entry into the workforce, providing unemployment insurance, or subsidizing pre-marital investment
The Discontinuous Nature of Kriging Interpolation for Digital Terrain Modeling
Kriging is a widely employed method for interpolating and estimating elevations from digital elevation data. Its place of prominence is due to its elegant theoretical foundation and its convenient practical implementation. From an interpolation point of view, kriging is equivalent to a thin-plate spline and is one species among the many in the genus of weighted inverse distance methods, albeit with attractive properties. However, from a statistical point of view, kriging is a best linear unbiased estimator and, consequently, has a place of distinction among all spatial estimators because any other linear estimator that performs as well as kriging (in the least squares sense) must be equivalent to kriging, assuming that the parameters of the semivariogram are known. Therefore, kriging is often held to be the gold standard of digital terrain model elevation estimation. However, I prove that, when used with local support, kriging creates discontinuous digital terrain models, which is to say, surfaces with “rips” and “tears” throughout them. This result is general; it is true for ordinary kriging, kriging with a trend, and other forms. A U.S. Geological Survey (USGS) digital elevation model was analyzed to characterize the distribution of the discontinuities. I show that the magnitude of the discontinuity does not depend on surface gradient but is strongly dependent on the size of the kriging neighborhood
Schumpeter and Personal Capitalism
In an earlier paper, I criticized Schumpeter\u27s account of the obsolescence of the entrepreneur in Capitalism, Socialism, and Democracy. That account rests, I argued, on a confusion about the nature of scientific knowledge and its role in the competences of the firm. This paper is an attempt to take up the argument again, moving it away from the doctrine-historical into the provinces of the economics of organization. Drawing on the work of Max Weber, as well as on a case study of the Swiss watch industry, the paper argues for the ineradicable role of personal capitalism, properly understood