Elastic waves in a soft electrically conducting solid in a strong magnetic field

Shear wave motion of a soft, electrically-conducting solid in the presence of a strong magnetic field excites eddy currents in the solid. These, in turn, give rise to Lorentz forces that resist the wave motion. We derive a mathematical model for linear elastic wave propagation in a soft electrically conducting solid in the presence of a strong magnetic field. The model reduces to an effective anisotropic dissipation term resembling an anisotropic viscous foundation. The application to magnetic resonance elastography, which uses strong magnetic fields to measure shear wave speed in soft tissues for diagnostic purposes, is considered

Shear waves in prestrained poroelastic media

Shear wave elastography measures shear wave speed in soft tissues for diagnostic purposes. In [1], shear wave speed was shown to depend on prestrain, but not necessarily prestress, in a perfused canine liver. We model this phenomenon by examining incremental waves in a pressurized poroelastic medium with incompressible phases. The analysis suggests novel restrictions on the strain energy functions for soft tissues

Strengthening governance through engaged societies : lessons from the implementation of poverty reduction strategies

In December 1999, the Boards of the World Bank and the International Monetary Fund approved a new approach to their relations with low-income countries. The approach was centered around the development and implementation of Poverty Reduction Strategies (PRS), which are intended to be country-driven and medium- to long-term in perspective, comprehensive and results-oriented, partnership-oriented, and built on broad-based participation. Against this tall order of business, experience to date has been varied, and much debate is ongoing on whether the approach can be considered more than"old wine in new bottles."This paper-based on the results of a thorough review of the five-year implementation experience-examines the implementation of the PRS approach from the point of view of participation and accountability. For some 50 countries adopting the approach since 1999, it discusses the factors which can facilitate the development of accountability and participatory governance mechanisms. Lessons learned from distinct country circumstances are analyzed, arguing that ownership of the PRS depends on the way countries and their external donor partners handle real tensions in the relationship between country ownership on the one hand, and perceptions of internationally-driven prescriptions on the other. The central message of the paper is that in several countries the PRS initiative has helped open up societies to forms of dialogue and contestability not previously experienced in-country or observed by external partners. This positive outcome, however, has been largely influenced by the extent to which the PRS process has reinforced existing trends and strengthened institutions already prone to open discussion of policy choices. The paper also shows that even in the best cases change has, to date, been largely in the area of process and that impact of participatory governance on policymaking, while emerging, is still a work in progress. The paper concludes with recommendations for how developing country societies might sustain real achievements in participatory governance and domestic accountability going forward, with external partners playing a key supportive role through harmonization and alignment.Governance Indicators,Social Accountability,Poverty Monitoring&Analysis,Achieving Shared Growth,Rural Poverty Reduction

Public Finances and Economic Transition

This paper analyzes developments in general government expenditures and revenues for 26 reforming ex-socialist economies (RESEs) over the period 1989-1994. The data indicate that, rather than uniformly converging to a “Western European” norm, RESEs have followed a variety of patterns, depending on how successful they have been in economic reform in general and in tackling the increase in the demand for social protection in particular. The paper conducts an empirical investigation of spending patterns and the sustainability of revenues required to maintain current government spending, and concludes that there are strong indications that the fiscal accounts will remain under pressure in a number of RESEs in the foreseeable future.economic transition, general government expenditures, public finance

Transition and the Fiscal Crisis in Central Europe

This paper argues that traditional explanations of the fiscal crisis in transition economies overlook the crucial interconnection between the reduction in subsidies expenditure and the decrease in profit tax revenues. It thus contends that the impact on the fiscal budget of the crisis of state-owned enterprises profitability has been largely overestimated in the literature. The net contribution to the government budget from the enterprise sector - defined as profit taxes net of cross-subsidization - has increased during the transition in Poland and Czechoslovakia, and has remained constant in Hungary. After reexamining the data, it is argued that - while it is undoubtable that the prospects for fiscal revenues are worrisome - the main determinant of the fiscal crisis is to the explosion of social security expenditures. The paper also assesses the applicability of these results to other former socialist economies.Poland, Hungary, Czechoslovakia, Eastern Europe, Socialist economies, economic transition, fiscal crisis, revenue crisis, social expenditures, pensions

Tajikistan : key priorities for climate change adaptation

How should Tajikistan adapt to ongoing and future climate change, in particular given the many pressing development challenges it currently faces? The paper argues that for developing countries like Tajikistan, faster economic and social development is the best possible defense against climate change. It presents some key findings from a recent nationally representative household survey to illustrate the strong public support for more climate change related spending on better management of water resources, disaster management, agriculture, and public health--four key sectors that the government's latest poverty reduction strategy identifies as being especially important from a climate change perspective. Finally, the paper argues that, as important as project-based adaptation measures may be, it is imperative that they be supported by an overall policy framework that provides a truly enabling environment to facilitate faster climate change adaptation.Science of Climate Change,Climate Change Mitigation and Green House Gases,Climate Change Economics,Water Supply and Sanitation Governance and Institutions,Population Policies

Economic transformation and the fiscal crisis : a critical look at the Central European experience of the 1990s

The authors argue that traditional explanations of the fiscal crisis in reforming ex-socialist economies overlook crucial connections between key components of the deficit - particularly between reductions in spending and declines in revenues. Almost all studies of the fiscal aspects of the transition stress the impact on the fiscal budget of the performance crisis in state-owned enterprises. The authors contend that this aspect of the fiscal crisis has been overstated. The enterprise sector's net contribution to the government budget - that is, net income from profit taxes after subtracting subsidies - has increased during the transition in Czechoslovakia and Poland and has not changed substantially in Hungary. After reexamining the data, the authors argue that although the fiscal crisis is certainly structural, the main blame should be attributed to the explosion in spending (especially social spending) rather than to the crisis in revenues. Many of the social costs of adjustment were previously hidden within the state-owned enterprises system. These social costs include unemployment benefits and the cost of supporting - through pensions or social assistance - the people displaced from the work force by the transformation. It is important to continue reforming the tax system and tax administration - to deal with the widespread hiding of profits and cheating on taxes - but all three countries already have relatively high levels of taxation. Society in the three countries may not be willing to provide the resources required to support or extend current spending levels.National Governance,Environmental Economics&Policies,Banks&Banking Reform,Public Sector Economics&Finance,Economic Theory&Research

Structural adjustment, ownership transformation, and size in Polish industry

The authors argue that significant adjustment took place in Polish industry after Poland's 1990 reforms. They analyze data on two- and three-digit manufacturing industries, disaggregated by firm ownership and size. By applying a statistical model to labor productivity growth, they try to disentangle structural determinants of the recovery from cyclical determinants. They contend that structural determinants outweigh cyclical ones. They find that the productive response of state enterprises was markedly different from that of private firms--private firms outperformed state enterprises (just as anecdotal evidence suggested). Size also matters, at least among private firms. Generally, there seem to be increasing returns to scale for private firms, except for very large enterprises (many of which were previously state-owned and may need further restructuring). The fact that size does not appear to matter among public enterprises suggests that several of them have not yet adopted optimal technologies and production processes.Banks&Banking Reform,Municipal Financial Management,Labor Policies,Environmental Economics&Policies,Economic Theory&Research,Environmental Economics&Policies,Banks&Banking Reform,Municipal Financial Management,Economic Theory&Research,Health Monitoring&Evaluation

The foreign-born population in the European Union and its contribution to national tax and benefit systems : some insights from recent household survey data

Despite the purported surge in internal migration following the 2004 enlargement of the European Union, data from the 2006 European Union Survey of Income and Living Conditions show that internal migrants are a relatively small share of the European Union's population. Depending on the exact definition used, only about 1 to 2 percent of the population of European Union-13 countries (members prior to the 2004 enlargement, not including Germany and Luxembourg) were born in other European Union countries, while the corresponding share for European Union-4 countries (Poland, Hungary, Czech Republic, and Slovakia) is even lower. By contrast, about 6 percent of the population of European Union-13 countries was born outside the European Union. On examining the demographic and socio-economic background of the migrant population (both from within as well as outside the European Union), this paper finds that migrants tend to include a concentration of both low as well as highly educated workers. Both sets of migrants uniformly contribute to raising the working-age population of receiving countries. Using data on average incomes and taxes paid and benefits received by migrant and non-migrant households, the authors find no evidence to support the contention that migrant workers contribute much less in taxes than the native-born population, or consume significantly higher benefits. On the contrary, our calculations suggest that migrant workers make a net contribution of approximately 42 billion euros to the national tax and benefit systems of European Union-13 countries.Population Policies,Gender and Law,,Gender and Law,Access to Finance