From plan to market : patterns of transition

In analyzing the transitional experience of countries in Central and Eastern Europe (CEE) and the former Soviet Union (FSU), the authors find strong common patterns for countries at similar stages of reform despite differences in initial conditions. To establish rankings, the authors create a reform index combining the intensity and duration of economic liberalization. Freeing domestic prices is one element of reform captured by the index; it was needed to enable governments to cut subsidies and restore macroeconomic balance. Other dimensions of reform captured by the index are liberalization of external trade, including foreign currency convertibility, and facilitation of private sector entry through privatization of state enterprises and improvements in the environment for private sector development. Some countries moved faster on reform than others, and one major reason appeared to have been the pace of political liberalization. Liberalization has, indeed, encouraged capital and labor to reallocate from industry toward services, many of which were previously repressed; and the repressed sectors fueled the return to positive growth in fast reformers. For slow reformers, the main problem in achieving stabilization has been the continued monetization of fiscal and quasi-fiscal deficits, associated with attempts to maintain employment in the old system. Among the policy implications are: 1) stabilization is a priority for the resumption of growth, and this requires extensive liberalization; 2) stabilization is made difficult by output contractions in the early stages of liberalization, by limited external financing, and by very large depreciations of the real exchange rate; and 3) there is no evidence that a slower pace of reform strengthens the fiscal position of slow reformers; their consolidated fiscal and quasi-fiscal deficits are quite high.Insurance&Risk Mitigation,Economic Conditions and Volatility,Environmental Economics&Policies,Economic Theory&Research,Insurance Law,Economic Conditions and Volatility,Economic Theory&Research,Environmental Economics&Policies,Insurance&Risk Mitigation,Insurance Law

Circumstance and choice : the role of initial conditions and policies in transition economies

The experience of countries in transition from a planned to a market-oriented economy has varied greatly. The clearest differences are between the East Asian countries, China and Vietnam, and the countries of Central and Eastern Europe (CEE) and the former Soviet Union (FSU). China and Vietnam have contained inflation and benefited from continued high growth in GDP since the beginning of their reforms, while all CEE and FSU countries have experienced large declines in output, and most have experienced hyperinflation. But even in CEE and the FSU, differences are marked. Some countries have lost over half of their GDP, and growth performance in a number of countries is still poor, while others are growing strongly. Some are still suffering from high inflation while others have successfully reduced annual inflation. What determines this divergence of outcomes across transition countries? No study so far has analyzed the interaction of all factors, including initial conditions, political change, and reforms, in a unified framework including CEE, the FSU, China, and Vietnam. The authors examine these broader interactions, but focus first on the role of initial conditions, such as initial macroeconomic distortions and differences in economic structure and institutions, which have been emphasized less in the literature. They find that initial conditions and economic policy jointly determine the large differences in economic performance among the 28 transition economies in the sample. Initial conditions dominate in explaining inflation, but economic liberalization is the most important factor determining differences in growth. But reform policy choices are not exogenous. They depend, in turn, on both initial conditions and political reform, with political reform the most important determinant of the speed and comprehensiveness of economic liberalization. Other findings provide additional insight into these relationships. Results show that liberalization has a negative contemporaneous impact, but a stronger positive effect on performance over time. The results also show that macroeconomic and structural distortions are negatively related to both policy and performance. Regarding the former, unfavorable initial conditions discourage policy reforms but do not diminish their effectiveness once they are implemented. The authors find some evidence that the influence of initial conditions diminishes over time. This is in part because many of the initial conditions are themselves modified in the course of transition. Monetary overhangs are dissipated through inflation, industrial overhang is eroded as plants shut down, and market memory returns through experience.Economic Conditions and Volatility,Economic Theory&Research,Enterprise Development&Reform,Environmental Economics&Policies,Banks&Banking Reform,Economic Theory&Research,Environmental Economics&Policies,Governance Indicators,Economic Conditions and Volatility,Achieving Shared Growth

Liquid-liquid coexistence in the phase diagram of a fluid confined in fractal porous materials

Multicanonical ensemble sampling simulations have been performed to calculate the phase diagram of a Lennard-Jones fluid embedded in a fractal random matrix generated through diffusion limited cluster aggregation. The study of the system at increasing size and constant porosity shows that the results are independent from the matrix realization but not from the size effects. A gas-liquid transition shifted with respect to bulk is found. On growing the size of the system on the high density side of the gas-liquid coexistence curve it appears a second coexistence region between two liquid phases. These two phases are characterized by a different behaviour of the local density inside the interconnected porous structure at the same temperature and chemical potential.Comment: 5 pages, 4 figures. To be published in Europhys. Letter

An exact minimum variance filter for a class of discrete time systems with random parameter perturbations

An exact, closed-form minimum variance filter is designed for a class of discrete time uncertain systems which allows for both multiplicative and additive noise sources. The multiplicative noise model includes a popular class of models (Cox-Ingersoll-Ross type models) in econometrics. The parameters of the system under consideration which describe the state transition are assumed to be subject to stochastic uncertainties. The problem addressed is the design of a filter that minimizes the trace of the estimation error variance. Sensitivity of the new filter to the size of parameter uncertainty, in terms of the variance of parameter perturbations, is also considered. We refer to the new filter as the 'perturbed Kalman filter' (PKF) since it reduces to the traditional (or unperturbed) Kalman filter as the size of stochastic perturbation approaches zero. We also consider a related approximate filtering heuristic for univariate time series and we refer to filter based on this heuristic as approximate perturbed Kalman filter (APKF). We test the performance of our new filters on three simulated numerical examples and compare the results with unperturbed Kalman filter that ignores the uncertainty in the transition equation. Through numerical examples, PKF and APKF are shown to outperform the traditional (or unperturbed) Kalman filter in terms of the size of the estimation error when stochastic uncertainties are present, even when the size of stochastic uncertainty is inaccurately identified

Opportunity Trajectory Reconstruction Techniques for Evaluation of ATC Systems

This paper describes some key points of a new tool being currently developed by Eurocontrol for the assessment of air traffic control (ATC) multisensor trackers performance. It summarizes the algorithmic foundations of the high-accuracy trajectory reconstruction process used to obtain reference trajectories from recorded measures. These trajectories will serve as a reference for the evaluation of the accuracy of ATC data processing centers. The performance of the system is illustrated with some reconstruction experiments on synthetic and real data

ASOHF: a new adaptive spherical overdensity halo finder

We present and test a new halo finder based on the spherical overdensity (SO) method. This new adaptive spherical overdensity halo finder (ASOHF) is able to identify dark matter haloes and their substructures (subhaloes) down to the scales allowed by the analysed simulations. The code has been especially designed for the adaptive mesh refinement cosmological codes, although it can be used as a stand-alone halo finder for N-body codes. It has been optimised for the purpose of building the merger tree of the haloes. In order to verify the viability of this new tool, we have developed a set of bed tests that allows us to estimate the performance of the finder. Finally, we apply the halo finder to a cosmological simulation and compare the results obtained to those given by other well known publicly available halo finders.Comment: Latex format, 16 pages, 11 postscript figures, accepted for publication in Astronomy and Astrophysic

Toward precision measurements in solar neutrinos

Solar neutrino physics enters a stage of precision measurements. In this connection we present a precise analytic description of the neutrino conversion in the context of LMA MSW solution of the solar neutrino problem. Using the adiabatic perturbation theory we derive an analytic formula for the $\nu_e$ survival probability which takes into account the non-adiabatic corrections and the regeneration effect inside the Earth. The probability is averaged over the neutrino production region. We find that the non-adiabatic corrections are of the order $10^{-9}-10^{-7}$. Using the formula for the Earth regeneration effect we discuss features of the zenith angle dependence of the $\nu_e$ flux. In particular, we show that effects of small structures at the surface of the Earth can be important.Comment: 26 pages, 6 figures. Version to appear in Nucl. Phys.

Adsorption in non interconnected pores open at one or at both ends: A reconsideration of the origin of the hysteresis phenomenon

We report on an experimental study of adsorption isotherme of nitrogen onto porous silicon with non interconnected pores open at one or at both ends in order to check for the first time the old (1938) but always current idea based on Cohan's description which suggests that the adsorption of gaz should occur reversibly in the first case and irreversibly in the second one. Hysteresis loops, the shape of which is usually associated to interconnections in porous media, are observed whether the pores are open at one or at both ends in contradiction with Cohan's model.Comment: 5 pages, 4 EPS figure

Entropy-induced separation of star polymers in porous media

We present a quantitative picture of the separation of star polymers in a solution where part of the volume is influenced by a porous medium. To this end, we study the impact of long-range-correlated quenched disorder on the entropy and scaling properties of $f$-arm star polymers in a good solvent. We assume that the disorder is correlated on the polymer length scale with a power-law decay of the pair correlation function $g(r) \sim r^{-a}$. Applying the field-theoretical renormalization group approach we show in a double expansion in $\epsilon=4-d$ and $\delta=4-a$ that there is a range of correlation strengths $\delta$ for which the disorder changes the scaling behavior of star polymers. In a second approach we calculate for fixed space dimension $d=3$ and different values of the correlation parameter $a$ the corresponding scaling exponents $\gamma_f$ that govern entropic effects. We find that $\gamma_f-1$, the deviation of $\gamma_f$ from its mean field value is amplified by the disorder once we increase $\delta$ beyond a threshold. The consequences for a solution of diluted chain and star polymers of equal molecular weight inside a porous medium are: star polymers exert a higher osmotic pressure than chain polymers and in general higher branched star polymers are expelled more strongly from the correlated porous medium. Surprisingly, polymer chains will prefer a stronger correlated medium to a less or uncorrelated medium of the same density while the opposite is the case for star polymers.Comment: 14 pages, 7 figure

Atenolol versus losartan in children and young adults with Marfan's syndrome

BACKGROUND : Aortic-root dissection is the leading cause of death in Marfan's syndrome. Studies suggest that with regard to slowing aortic-root enlargement, losartan may be more effective than beta-blockers, the current standard therapy in most centers. METHODS : We conducted a randomized trial comparing losartan with atenolol in children and young adults with Marfan's syndrome. The primary outcome was the rate of aortic-root enlargement, expressed as the change in the maximum aortic-root-diameter z score indexed to body-surface area (hereafter, aortic-root z score) over a 3-year period. Secondary outcomes included the rate of change in the absolute diameter of the aortic root; the rate of change in aortic regurgitation; the time to aortic dissection, aortic-root surgery, or death; somatic growth; and the incidence of adverse events. RESULTS : From January 2007 through February 2011, a total of 21 clinical centers enrolled 608 participants, 6 months to 25 years of age (mean [+/- SD] age, 11.5 +/- 6.5 years in the atenolol group and 11.0 +/- 6.2 years in the losartan group), who had an aorticroot z score greater than 3.0. The baseline-adjusted rate of change (+/- SE) in the aortic-root z score did not differ significantly between the atenolol group and the losartan group (-0.139 +/- 0.013 and -0.107 +/- 0.013 standard-deviation units per year, respectively; P = 0.08). Both slopes were significantly less than zero, indicating a decrease in the degree of aortic-root dilatation relative to body-surface area with either treatment. The 3-year rates of aortic-root surgery, aortic dissection, death, and a composite of these events did not differ significantly between the two treatment groups. CONCLUSIONS : Among children and young adults with Marfan's syndrome who were randomly assigned to losartan or atenolol, we found no significant difference in the rate of aorticroot dilatation between the two treatment groups over a 3-year period