Farm size and nonparametric efficiency measurements for coffee farms in Vietnam

We study the efficiency of smallholder coffee farms in Vietnam. Data from a 2004 survey of farms in two districts in Dak Lak Province are used in a two-step analysis. In the first step, technical and cost efficiency measures are calculated using DEA. In the second step, Tobit regressions are used to identify factors correlated with technical and cost inefficiency. Results indicate that small farms were less efficient than large farms. Inefficiencies observed on small farms appear to be related, in part, to the scale of investments in irrigation infrastructure.Farm Management,

Superconducting applications in propulsion systems. Magnetic insulation for plasma propulsion devices

The purpose of this paper is to review the status of knowledge of the basic concepts needed to establish design parameters for effective magnetic insulation. The objective is to estimate the effectiveness of the magnetic field in insulating the plasma, to calculate the magnitude of the magnetic field necessary to reduce the heat transfer to the walls sufficiently enough to demonstrate the potential of magnetically driven plasma rockets

In-Medium Effects on Charmonium Production in Heavy-Ion Collisions

Charmonium production in heavy-ion collisions is investigated within a kinetic theory framework incorporating in-medium properties of open- and hidden-charm states in line with recent QCD lattice calculations. A continuously decreasing open-charm threshold across the phase boundary of hadronic and quark-gluon matter is found to have important implications for the equilibrium abundance of charmonium states. The survival of $J/\psi$ resonance states above the transition temperature enables their recreation also in the Quark-Gluon Plasma. Including effects of chemical and thermal off-equilibrium, we compare our model results to available experimental data at CERN-SPS and BNL-RHIC energies. In particular, earlier found discrepancies in the $\psi'/\psi$ ratio can be resolved.Comment: 4 pages RevTex including 4 eps-figures. v2: Minor modifications and clarifications, typos corrected, Fig. 4 update

Impulse approximation in the n p --> d pi^0 reaction reexamined

The impulse approximation (one-body operator) in the n p --> d pi^0 reaction is reexamined with emphasis on the issues of reducibility and recoil corrections. An inconsistency when one pion exchange is included in the production operator is demonstrated and then resolved via the introduction of "wave function corrections" which nearly vanish for static nucleon propagators. Inclusion of the recoil corrections to the nucleon propagators is found to change the magnitude and sign of the impulse production amplitude, worsening agreement with the experimental cross section by approximately 30%. A cutoff is used to account for the phenomenological nature of the external wave functions, and is found to have a significant impact up to approximately 2.5 GeV.Comment: Published versio

Agricultural Prices and Income Distribution among Farmers: A Whole-Household, Multi-Country, Multi-Year Analysis

Recent studies have emphasized that the poorest farmers are often net buyers of key commodities and therefore harmed by rising prices. We use LSMS data from Tanzania, Vietnam and Guatemala to test the degree of net purchases or sales by income level. We find that poorer farmers may be net buyers of individual crops, but only the poorest are net buyers of all crops. More generally, net sales among poor farmers are low. We conclude that agricultural price changes have a diverse but limited influence on poor farmers’ welfare, because their farm sales tend to be offset by food purchases.market participation, poverty, inequality, multi-continent multicountry, Agricultural Finance,

Linkages between Market Participation and Productivity: Results from a Multi-Country Farm Household Sample

We build upon international trade literature to analyze the direction of causality between market participation and productivity. Cross-country household data from Tanzania, Vietnam and Guatemala are used in a 2SLS approach with market participation and productivity as endogenous variables. Results indicate that households with higher productivity tend to participate in agricultural markets regardless of market access factors. In contrast, having better market access does not necessarily lead to higher productivity. This finding suggests that investments in market access infrastructure provide minimal, if any, improvements in agricultural productivity; whereas programs targeted at enhancements in farm structure and capital have the potential to increase both productivity and market participation.International Relations/Trade, Marketing, Productivity Analysis,

Emerging patterns of species richness, diversity, population density, and distribution in the skates (Rajidae) of Alaska

Six years of bottom-trawl survey data, including over 6000 trawls covering over 200 km2 of bottom area throughout Alaska’s subarctic marine waters, were analyzed for patterns in species richness, diversity, density, and distribution of skates. The Bering Sea continental shelf and slope, Aleutian Islands, and Gulf of Alaska regions were stratified by geographic subregion and depth. Species richness and relative density of skates increased with depth to the shelf break in all regions. The Bering Sea shelf was dominated by the Alaska skate (Bathyraja parmifera), but species richness and diversity were low. On the Bering Sea slope, richness and diversity were higher in the shallow stratum, and relative density appeared higher in subregions dominated by canyons. In the Aleutian Islands and Gulf of Alaska, species richness and relative density were generally highest in the deepest depth strata. The data and distribution maps presented here are based on species-level data collected throughout the marine waters of Alaska, and this article represents the most comprehensive summary of the skate fauna of the region published to date

Going Green with IT: A Study of Energy Consumption by Home and School Information Technology Systems in the College of Information at the University of North Texas

This paper addresses the strategies introduced by the College of Information at the University of North Texas to monitor and begin implementing approaches to enable the college to move toward the university???s strategic goal of becoming a climate-neutral, ???Green University??? [3]. Data based on monitoring selected office and home inventories of information technology equipment were used to generate estimated production-level use and standby (vampire) consumption of electrical energy. Sample-based estimations and projections regarding 2008 to 2009 progress indicate that that the College of Information at the University of North Texas has made extensive progress over one year in reducing the energy consumed by its information technology systems. New computer and printer systems have greater processing power and capabilities but consume no more power than the ones they replace, when in full operation. The computer systems consume one-half to one-third (and in some cases oneseventh) the power of the previous systems when in 'sleep???, 'hibernate' or 'shut down' states that qualify for the standard definition of consuming stand by power. The authors estimate that these actions have brought the college at least halfway toward its five-year goal of becoming climate neutral, during the first year of the initiative

Cost-effective use of liquid nitrogen in cryogenic wind tunnels, phase 2

Cryogenic seal tests were performed and Rulon A was selected for the subject nutating positive displacement expander. A four-chamber expander was designed and fabricated. A nitrogen reliquefier flow system was also designed and constructed for testing the cold expander. Initial tests were unsatisfactory because of high internal friction attributed to nutating Rulon inlet and outlet valve plates. Replacement of the nutating valves with cam-actuated poppet valves improved performance. However, no net nitrogen reliquefaction was achieved due to high internal friction. Computer software was developed for accurate calculation of nitrogen reliquefaction from a system such as that proposed. These calculations indicated that practical reliquefaction rates of 15 to 19 percent could be obtained. Due to mechanical problems, the nutating expander did not demonstrate its feasibility nor that of the system. It was concluded that redesign and testing of a smaller nutating expander was required to prove concept feasibility