Law in Transition and Development: The Case of Russia

The rise of barter and non-cash payments has become a dominant feature of the Russian transition to a market economy. This paper confronts with empirical evidence two approaches to explain barter in Russia: the ’illusion view’ and the ’trust view’ of barter. The ’illusion view’ suggests that barter allows the parties to pretend that the manufacturing sector in Russia is producing value added by enabling this sector to sell its output at a higher price than its market value. The ’trust view’ sees barter as an institution to deal with the absence of trust and liquidity in the Russian economy. We confront the prediction of both explanations with actual data on barter in Ukraine in 1997. The data reject the ’illusion view‘ in favor of the ‘trust view‘ of barter

Cross-Entropy Randomized Motion Planning

Abstract—This paper is concerned with motion planning for nonlinear robotic systems operating in constrained environments. Motivated by recent developments in sampling-based motion planning and Monte Carlo optimization we propose a general randomized path planning method based on sampling in the space of trajectories. The idea is to construct a probability distribution over the set of feasible paths and to perform the search for an optimal trajectory through importance sampling. At the core of the approach lies the cross-entropy method for estimation of rare-event probabilities. The algorithm recursively approximates the optimal sampling distribution which guides the set of sampled trajectories towards regions of progressively lower cost until converging to a delta distribution at the optimum. Our main goal is to provide a framework for consistent adaptive sampling correlating the spatial structure of trajectories and their computed costs. The approach is illustrated with two simple examples–a point mass vehicle and the Dubins car, and is then applied to a simulated helicopter flying optimally in a 3-D terrain

The growth of interest for astronomical X-ray polarimetry

Astronomical X-ray polarimetry was first explored in the end of the 60's by pioneering rocket instruments. The craze arising from the first discoveries on stellar and supernova remnant X-ray polarization led to the addition of X-ray polarimeters on-board of early satellites. Unfortunately, the inadequacy of the diffraction and scattering technologies required to measure polarization with respect to the constraints driven by X-ray mirrors and detectors, coupled to long integration times, slowed down the field for almost 40 years. Thanks to the development of new, highly sensitive, compact X-ray polarimeters in the beginning of the 2000's, the possibility to observe astronomical X-ray polarization is rising again and scientists are now ready to explore the high energy sky thanks to modern X-ray polarimeters. In the forthcoming years, several X-ray missions (both rockets, balloons and satellites) will open a new observational windows. A wind of renewal blows over the area of X-ray polarimetry and this paper presents for the first time a quantitative assessment, all based on scientific literature, of the growth of interest for astronomical X-ray polarimetry.Comment: 7 pages, 2 figures, accepted for publication in Galaxies, to be published in the special issue "The Bright Future of Astronomical X-ray Polarimetry

The Vanishing Barter Economy in Russia: A Test of the Virtual Economy Hypothesis? Reply to Barry Ickes

This paper is a reply to Barry Ickes' critique of my paper “Trust versus Illusion: What is Driving Demonetization in Russia?” in which I show that the data reject Barry Ickes' Virtual Economy explanation of barter in Russia in favor of an institutional explanation based on the lack of trust