Plasticity of differentiated cells in wound repair and tumorigenesis, Part II: Skin and intestine

Recent studies have identified and begun to characterize the roles of regenerative cellular plasticity in many organs. In Part I of our two-part Review, we discussed how cells reprogram following injury to the stomach and pancreas. We introduced the concept of a conserved cellular program, much like those governing division and death, which may allow mature cells to become regenerative. This program, paligenosis, is likely necessary to help organs repair the numerous injuries they face over the lifetime of an organism; however, we also postulated that rounds of paligenosis and redifferentiation may allow long-lived cells to accumulate and store oncogenic mutations, and could thereby contribute to tumorigenesis. We have termed the model wherein differentiated cells can store mutations and then unmask them upon cell cycle re-entry the ‘cyclical hit’ model of tumorigenesis. In the present Review (Part II), we discuss these concepts, and cell plasticity as a whole, in the skin and intestine. Although differentiation and repair are arguably more thoroughly studied in skin and intestine than in stomach and pancreas, it is less clear how mature skin and intestinal cells contribute to tumorigenesis. Moreover, we conclude our Review by discussing plasticity in all four organs, and look for conserved mechanisms and concepts that might help advance our knowledge of tumor formation and advance the development of therapies for treating or preventing cancers that might be shared across multiple organs

A Tale of Two Labor Markets: Intergenerational Occupational Mobility in Britain and the U.S. Since 1850

The U.S. both tolerates more inequality than Europe and believes its economic mobility is greater than Europe's. These attitudes and beliefs help account for differences in the magnitude of redistribution through taxation and social welfare spending. In fact, the U.S. and Europe had roughly equal rates of inter-generational occupational mobility in the late twentieth century. We extend this comparison into the late nineteenth century using longitudinal data on 23,000 nationally-representative British and U.S. fathers and sons. The U.S. was substantially more mobile then Britain through 1900, so in the experience of those who created the U.S. welfare state in the 1930s, the U.S. had indeed been "exceptional." The margin by which U.S. mobility exceeded British mobility was erased by the 1950s, as U.S. mobility fell compared to its nineteenth century levels.

Economic Crises: Evidence and Insights from East Asia

macroeconomics, Economic Crises, East Asia

CASH ETHANOL CROSS-HEDGING OPPORTUNITIES

Increased use of alternative fuels and low commodity prices have contributed to the recent expansion of the ethanol industry. As with any competitive industry, there exists some level of output price risk in the form of volatility. Yet, no actively traded ethanol futures market exists to transfer output price risk to. This study reports estimated minimum variance cross-hedge ratios between Michigan spot cash ethanol and the New York Mercantile Exchange (NYMEX) unleaded gasoline futures for 1-, 4-, 8-, 16-, and 24-week hedging periods. The research yields two results. First, the appropriate quantity of ethanol to hedge with one 42,000 NYMEX unleaded gasoline futures contract for each respective hedging period is realized. Second, the magnitude of the quantities of ethanol required to implement an effective minimum variance cross-hedge ratio is recognized as a possible deterrent to ethanol buyers and sellers from entering into a cross-hedge.Marketing, Resource /Energy Economics and Policy,

MARKET INTEGRATION: CASE STUDIES OF STRUCTURAL CHANGE

The grain/oilseed industry is undergoing considerable structural change in the form of mergers and the addition of new processing facilities to add value beyond commodity grade. The rapid structural changes in this industry call into question the relevance of previous research conducted in these areas. Focusing on two structural change events in northeast Missouri as case studies provides an incisive glimpse at the larger impact of structural change on the grain/oilseed industry. This study addresses the merger of Archer Daniels Midland and Quincy Grain, and the opening of a producer-owned ethanol plant in northeast Missouri to determine if these structural change events altered pricing patterns and linkages in Missouri grain/oilseed markets, and assess the need for re-specification of conventional economic models for price analysis in cases of potential structural change. This research utilizes a three-tier statistical analysis of cointegration tests, Flexible Least Squares analysis, and impulse response functions derived from Vector Autoregressive modeling to investigate the Law of One Price and price relationships among four Missouri grain/oilseed markets. The results are consistent with the Law of One Price, supporting the ideology that markets work, and implying that localized structural change may not significantly affect research shelf-life.Ethanol, Consolidation, Structural Change, Industrial Organization,

Design of fixtures and specimens for high strain-rate tensile testing on a drop tower

Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2009.Cataloged from PDF version of thesis.Includes bibliographical references (p. 38-39).Drop towers are used to perform mechanical tests at strain rates similar to those experienced in automobile crashes. By their nature, drop towers are configured to perform compression tests only. This project aims to design a set of fixtures and specimens to allow the machine to perform tensile tests. Two major design options were considered and analyzed using engineering mechanics and finite element analysis. The design selected used a double dog-bone specimen bent into a "U"-shape and impacted by a weighted force sensor with a steel tup attached to the bottom. The appropriate fixtures were designed. Future work on this project includes manufacturing of the fixtures, design and construction of a method for creating the specimens, and physical tensile tests using the new machine configuration.by Jason J. Chan.S.B