CFD Code Survey for Thrust Chamber Application

In the quest fo find analytical reference codes, responses from a questionnaire are presented which portray the current computational fluid dynamics (CFD) program status and capability at various organizations, characterizing liquid rocket thrust chamber flow fields. Sample cases are identified to examine the ability, operational condition, and accuracy of the codes. To select the best suited programs for accelerated improvements, evaluation criteria are being proposed

Charge correlations in the weakly doped t-J model calculated by projection technique

We study frequency- and wave-vector dependent charge correlations in weakly doped antiferromagnets using Mori-Zwanzig projection technique. The system is described by the two-dimensional t-J model. The ground state is expressed within a cumulant formalism which has been successfully applied to study magnetic properties of the weakly doped system. Within this approach the ground state contains independent spin-bag quasiparticles (magnetic polarons). We present results for the charge-density response function and for the optical conductivity at zero temperature for different values of t/J. They agree well with numerical results calculated by exact diagonalization techniques. The density response function for intermediate and large momenta shows a broad continuum on energy scales of order of several t whereas the optical conductivity for \omega > 0 is dominated by low energy excitations (at 1.5 - 2 J). We show that these weak-doping properties can be well understood by transitions between excited states of spin-bag quasiparticles.Comment: 10 pages, 5 figs., to appear in Europ. Phys. J.

Glutamatergic-dopaminergic balance in the brain. Its importance in motor disorders and schizophrenia

Dopamine appears to be of less importance in the regulation of psychomotor functions than was previously thought. A central dopaminergic-glutamatergic balance may be important for both akinetic motor disorders and psychosis. In Parkinson's disease glutamate antagonists may counteract central glutamatergic hyperactivity and may be of value as anti-parkinsonian drugs. An increase of dopaminergic activity and/or a reduction of glutamatergic activity may contribute to the development of paranoid hallucinatory psychosis in schizophrenic patients and of pharmacotoxic psychosis in Parkinson's disease. Because of possibly severe side-effects of glutamatergic antagonists and agonists in the treatment of akinesia and psychosis, the development of partial glutamate agonists/antagonists could be an alternative strategy capable of producing antipsychotic or anti-kinetic effects with only mild adverse reaction

Enlargement of Trade Blocs: National Welfare Effects If Trade Is Liberalized

Small countries may benefit from the formation of a trade bloc, since their combined market power will enable them to manipulate the terms of trade. The question of interest is whether countries will benefit from the enlargement of a trading bloc, if trade liberalization induces countries to substitute domestic support measures for conventional border protection. The paper deals with this question by analyzing the conditions for positive welfare effects resulting from the enlargement of a trade bloc. Based on a partial equilibrium trade model, we consider a game in production taxes/subsidies between two trade blocs. The tax/subsidy instrument may capture the production effect which can be induced by a combination of environmental, health or safety rules. The paper demonstrates that national welfare effects from the enlargement of a trading bloc depend crucially on a member country's net trade flow and the relative market power of the trade bloc. The theoretical analysis is supplemented by a numerical analysis estimating the potential welfare gains of EU enlargement on the major grain crop markets. Based on the scenarios that the EU operates either as a monopoly or competes with the rest of the world within a duopoly, upper and lower bounds of potential welfare effects resulting from enlargement are estimated. The results suggest that welfare effects on the major European grain markets are very small in proportion to the total production value. We thereby conclude that political reasons are likely to remain the main motivation for further EU enlargement.trade bloc, trade liberalization, game theory, European Union, International Relations/Trade, D6, F11, Q17, C7,

Land Rental Markets in the Process of Rural Structural Transformation: Productivity and Equity Impacts from China

While the importance of land rental for overall economic development has long been recognized in theory, empirical evidence on the productivity and equity impact of such markets and the extent to which they realize their potential has been scant. Representative data from China's nine most important agricultural provinces illustrate the impact of rental markets on households' economic strategies, their welfare, and productivity of land use at the plot level. While there are positive impacts in each of these dimensions, transaction costs constrain participation by many producers, thus preventing rental markets from attaining their full potential. Factors that increase transaction costs are identified, together with a rough estimate of the productivity- and equity- impact of removing them.Land Economics/Use,

Economic and Social Impacts of Self-Help Groups in India

We use a combination of pipeline comparison, propensity score matching, and double differences to evaluate economic and social impacts of a large community driven development program in India. While we find positive empowerment and nutritional effects for households in program areas, allowing heterogeneity of program impact yields additional insights. First, social and economic empowerment increased equally for participants and non-participants in program areas, pointing towards positive externalities. Second, nutritional benefits were more pronounced for new participants than for members of pre-existing self-help groups who joined the program. Third, evidence of higher consumption -but not income or asset formation- by new and converted participants suggests that at the point of the survey, the program's main economic impact had been through consumption smoothing and diversification of income sources.Food Security and Poverty,