Probing the isospin dependent mean field and nucleon nucleon cross section in the medium by the nucleon emissions

We study the isospin effects of the mean field and two-body collision on the nucleon emissions at the intermediate energy heavy ion collisions by using an isospin dependent transport theory. The calculated results show that the nucleon emission number $N_{n}$ depends sensitively the isospin effect of nucleon nucleon cross section and weakly on the isospin dependent mean field for neutron-poor system in higher beam energy region . In particular, the correlation between the medium correction of two-body collision and the momentum dependent interaction enhances the dependence of nucleon emission number $N_{n}$ on the isospin effect of nucleon nucleon cross section. On the contrary, the ratio of the neutron proton ratio of the gas phase to the neutron proton ratio of the liquid phase, i.e., the degree of isospin fractionation $_{b}/_{b}$ depends sensitively on the isospin dependent mean field and weakly on the isospin effect of two-body collision for neutron-rich system in the lower beam energy region. In this case, $N_{n}$ and $_{b}/_{b}$ are the probes for extracting the information about the isospin dependent nucleon nucleon cross section in the medium and the isospin dependent mean field,respectively.Comment: 4 pages,4 figure

The Demand for Current Public Expenditure in Fiji: Theory and Empirical Results

The purpose of this paper is to analyse government expenditure in Iran using annual time series data for the period 1963-2000. Various theories of the size of government are reviewed and a distinction is made between economic/structural determinants and institutional determinants. Categorising the theories of government expenditure in this way suggests the application of non-nested tests as a mechanism whereby the relative importance of the two broad theoretical categories can be determined. The empirical results, indicating "double rejection", reveal that neither the economic/structural determinants nor the institutional determinants alone are sufficient to explain government expenditure in Iran. A comprehensive, incorporating explanatory variables from both models provides a robust explanation of the data. This paper presents the first empirical estimates of the own-price elasticity of the demand, and income elasticity of the demand, for current government expenditures in Iran

Economic Mobility: Is the American Dream Alive and Well?

Draws on research analysis to outline what economic mobility is, why it matters in today's economy, and why it is important for policy makers to focus on mobility as part of the ongoing national economic debate

Colloidal diffusion and hydrodynamic screening near boundaries

The hydrodynamic interactions between colloidal particles in small ensembles are measured at varying distances from a no-slip surface over a range of inter-particle separations. The diffusion tensor for motion parallel to the wall of each ensemble is calculated by analyzing thousands of particle trajectories generated by blinking holographic optical tweezers and by dynamic simulation. The Stokesian Dynamics simulations predict similar particle dynamics. By separating the dynamics into three classes of modes: self, relative and collective diffusion, we observe qualitatively different behavior depending on the relative magnitudes of the distance of the ensemble from the wall and the inter-particle separation. A simple picture of the pair-hydrodynamic interactions is developed, while many-body-hydrodynamic interactions give rise to more complicated behavior. The results demonstrate that the effect of many-body hydrodynamic interactions in the presence of a wall is much richer than the single particle behavior and that the multiple-particle behavior cannot be simply predicted by a superposition of pair interactions

Developments in Retirement Provision: Global Trends and Lessons from Australia and the US

Retirement systems should be conceived of as long-term financial contracts under which workers' contributions today are exchanged for benefits paid to the elderly tomorrow. Such contracts are said to be well-managed if the transactions are handled in an affordable, reliable, and efficient manner. Yet all pension systems are forced to operate under a multitude of constraints including participants' ability and willingness to save; the availability of assets with which to convert current saving into future retirement benefits; the limitations of imperfect capital markets; political influences imposed by stakeholders; county macroeconomic conditions; and as we are becoming increasingly aware, global business cycles. If pensions are to continue to meet the needs of an aging world, it is imperative to prepare for emerging challenges as these systems evolve through time. In these remarks we first show how global demographic change is driving pension change throughout the world. Next we describe and compare developments in old-age provision over the last decade in Australia and the United States, and outline the key issues facing retirement systems in both nations. There are many differences between the experiences of the two countries, but as we shall show there are also common themes. Finally we identify key pension reform design issues facing Australia and the US in the upcoming decades.

"Regulating Healthcare Technologies and Medical Supplies: A Comparative Overview"

A complex relationship exists among EU regulations, current national practices and rules, institutional capacities to implement regulatory adjustments and the legacy of past health and regulatory policy and traditions. However, there is little empirical information on medical devices policy, the medical devices industry, and the assurance of medical device safety and usage. Drawing on a review of the secondary literature and on-going field work, the evidence suggests that the current mix of statecentric and self-regulatory traditions will be as important in determining the implementation and final outcomes of EU-rules as the new rules themselves. EU directives redesign rules, but they do not necessarily lead to institutional change, create institutional capacities, or alter old practices in the short term. Neither EU directives nor national regulatory adjustments determine the "man-machine/skill-experience" interface which is shaped and influenced by local medical traditions and the acceptance of these traditions by local publics

Hydrodynamic interactions of spherical particles in Poiseuille flow between two parallel walls

We study hydrodynamic interactions of spherical particles in incident Poiseuille flow in a channel with infinite planar walls. The particles are suspended in a Newtonian fluid, and creeping-flow conditions are assumed. Numerical results, obtained using our highly accurate Cartesian-representation algorithm [Physica A xxx, {\bf xx}, 2005], are presented for a single sphere, two spheres, and arrays of many spheres. We consider the motion of freely suspended particles as well as the forces and torques acting on particles adsorbed at a wall. We find that the pair hydrodynamic interactions in this wall-bounded system have a complex dependence on the lateral interparticle distance due to the combined effects of the dissipation in the gap between the particle surfaces and the backflow associated with the presence of the walls. For immobile particle pairs we have examined the crossover between several far-field asymptotic regimes corresponding to different relations between the particle separation and the distances of the particles from the walls. We have also shown that the cumulative effect of the far-field flow substantially influences the force distribution in arrays of immobile spheres. Therefore, the far-field contributions must be included in any reliable algorithm for evaluating many-particle hydrodynamic interactions in the parallel-wall geometry.Comment: submitted to Physics of Fluid

Extended ASP tableaux and rule redundancy in normal logic programs

We introduce an extended tableau calculus for answer set programming (ASP). The proof system is based on the ASP tableaux defined in [Gebser&Schaub, ICLP 2006], with an added extension rule. We investigate the power of Extended ASP Tableaux both theoretically and empirically. We study the relationship of Extended ASP Tableaux with the Extended Resolution proof system defined by Tseitin for sets of clauses, and separate Extended ASP Tableaux from ASP Tableaux by giving a polynomial-length proof for a family of normal logic programs P_n for which ASP Tableaux has exponential-length minimal proofs with respect to n. Additionally, Extended ASP Tableaux imply interesting insight into the effect of program simplification on the lengths of proofs in ASP. Closely related to Extended ASP Tableaux, we empirically investigate the effect of redundant rules on the efficiency of ASP solving. To appear in Theory and Practice of Logic Programming (TPLP).Comment: 27 pages, 5 figures, 1 tabl