Subextensive Scaling in the Athermal, Quasistatic Limit of Amorphous Matter in Plastic Shear Flow

We present the results of numerical simulations of an atomistic system undergoing plastic shear flow in the athermal, quasistatic limit. The system is shown to undergo cascades of local rearrangements, associated with quadrupolar energy fluctuations, which induce system-spanning events organized into lines of slip oriented along the Bravais axes of the simulation cell. A finite size scaling analysis reveals subextensive scaling of the energy drops and participation numbers, linear in the length of the simulation cell, in good agreement with the observed real-space structure of the plastic events.Comment: 4 pages, 6 figure

Efficient simulations of charged colloidal dispersions: A density functional approach

A numerical method is presented for first-principle simulations of charged colloidal dispersions in electrolyte solutions. Utilizing a smoothed profile for colloid-solvent boundaries, efficient mesoscopic simulations are enabled for modeling dispersions of many colloidal particles exhibiting many-body electrostatic interactions. The validity of the method was examined for simple colloid geometries, and the efficiency was demonstrated by calculating stable structures of two-dimensional dispersions, which resulted in the formation of colloidal crystals.Comment: 6 pages, 4 figure

Fairtrade and market failures in agricultural commodity markets

This paper concerns an NGO intervention in agricultural commodity markets known as Fairtrade. Fairtrade pays producers a minimum unit price and provides capacity building support to member cooperative organizations. Fairtrade's organizational capacity support targets those factors believed to reduce the commodity producer's share of returns. Specifically, Fairtrade justifies its intervention in markets like coffee by claiming that market power and a lack of capacity in producer organizations'marks down'the prices producers receive. As the market share of Fairtrade coffee grows in importance, its intervention in commodity markets is of increasing interest. Using an original data set collected from fieldwork in Costa Rica, this paper assesses the role of Fairtrade in overcoming the market factors it claims limits producer returns. Features of the Costa Rican input market for coffee permit a generalization of the results. The empirical results find that market power is a limiting factor in the Costa Rican market and that Fairtrade does improve the efficiency of cooperatives, thereby increasing the returns to producers. These results do not depend on the minimum price policy of Fairtrade and therefore can inform on its organizational support activities. Finally, the results also suggest that producers selling to vertically integrated, multinational coffee mills face lower producer price'mark-downs'compared with domestically owned non-cooperative mills. This result contradicts the popular view that the increasing concentration of vertically integrated multinational firms accounts for a decline in producers'share of coffee returns.Markets and Market Access,Crops&Crop Management Systems,Access to Markets,Commodities,Economic Theory&Research

Market Power and/or Efficiency: An Application to U.S. Food Processing

This article separates oligopoly-power and cost-efficiency effects of changes in industrial concentration and assesses their impact on output prices in 32 food-processing industries. Empirical results indicate that although concentration induces cost efficiency in one-third of the industries, oligopoly-power effects either dominate cost efficiency or reinforce inefficiency, resulting in higher output prices in most industries. The article also provides fresh econometric estimates of oligopoly power and economies of size for the industries in question.industrial concentration, economies of scale, industrial organization, oligopoly power, food processing, Agribusiness, Industrial Organization, Productivity Analysis, L00, L11, L13, L66,

Parallel packing of &#945;-helices in crystals of the zervamicin IIA analog Boc-Trp-Ile-Ala-Aib-Ile-Val-Aib-Leu-Aib-Pro-OMe.2H<SUB>2</SUB>0

An apolar synthetic analog of the first 10 residues at the NH2-terminal end of zervamicin HA crystallizes in the triclinic space group P1 with cell dimensions a = 10.206 &#177; 0.002 A, b = 12.244 &#177; 0.002 A, c = 15.049 &#177; 0.002 A, &#945; = 93.94 &#177; 0.01&#176;, &#946; = 95.10 &#177; 0.01&#176;, &#947; = 104.56 &#177; 0.01&#176;, Z = 1, C60H97N1103.2H2O. Despite the relatively few a-aminoisobutyric acid residues, the peptide maintains a helical form. The first intrahelical hydrogen bond is of the 310 type between N(3) and 0(0), followed by five &#945;-helix-type hydrogen bonds. Solution 1H NMR studies in chloroform also favor a helical conformation, with seven solvent-shielded NH groups. Continuous columns are formed by head-to-tail hydrogen bonds between the helical molecules along the helix axis. The absence of polar side chains precludes any lateral hydrogen bonds. Since the peptide crystallizes with one molecule in a trilinic space group, aggregation of the helical columns must necessarily be parallel rather than antiparallel. The packdng of the columns is rather inefficient, as indicated by very few good van der Waals' contacts and the occurrence of voids between the molecules

MANDATORY VERSUS VOLUNTARY PRICE REPORTING: AN EMPIRICAL INVESTIGATION OF THE MARKET TRANSPARENCY CONTROVERSY

The ability of the former voluntary price reporting system to generate market transparency in U.S. livestock markets was called into question by producer groups and academic research prior to the new federal system of mandatory price reporting being implemented. The market transparency issue is investigated by comparing price data collected from the former AMS voluntary price reporting system to mandatory price reporting data for live slaughter steers collected by the State of South Dakota before the advent of the new federal system. The relationship between a set of public price report series and the South Dakota mandatory price series is analyzed using cointegration techniques. The empirical findings indicate a strong long-run and short-run integrated relationship between the mandatory price series and a majority of the selected public price reports. We conclude that in the cash market for live steers in South Dakota, the former voluntary price reporting system did foster market transparency and aided in the price discovery process.Marketing,

The Efficacy of the Grid Marketing Channel for Fed Cattle

Beef industry data suggest that carcass yield and quality grades have shown little improvement over the last six years. Trend analysis of grid market share and carcass quality suggests that grid pricing has not made sufficient progress in achieving the goals envisioned for it as a value based marketing system.grid pricing, price discovery, price reporting, slaughter cattle