Purification-based metric to measure the distance between quantum states and processes

In this work we study the properties of an purification-based entropic metric for measuring the distance between both quantum states and quantum processes. This metric is defined as the square root of the entropy of the average of two purifications of mixed quantum states which maximize the overlap between the purified states. We analyze this metric and show that it satisfies many appealing properties, which suggest this metric is an interesting proposal for theoretical and experimental applications of quantum information.Comment: 11 pages, 2 figures. arXiv admin note: text overlap with arXiv:quant-ph/0408063, arXiv:1107.1732 by other author

ASSET OWNERSHIP AND WORKING CAPITAL CONSTRAINTS IN A POST-REFORM ENVIRONMENT: IMPLICATIONS FOR SECOND GENERATION REFORMS IN ZAMBIA

Using a 5,000 household panel from Zambia, we find that asset ownership, but not access to fertilizer, has an extremely important impact on output and that investment in oxen would yield returns above the market rate. Policies should thus focus on asset ownership more than on short term working capital.Community/Rural/Urban Development, Consumer/Household Economics,

ENTREPRENEURSHIP AND LIQUIDITY CONSTRAINTS IN DEPRIVED AREAS: EVIDENCE FROM THE SLUMS OF RIO DE JANEIRO

Several economic models have described the theoretical causes and onsequences of 'credit rationing' and 'under-investment'; one string of this literature shows the long-run effects of initial wealth distribution and entrepreneurial ability on the process of occupational choice and performance, and its consequences on inequality. Surprisingly, there is very little micro-level evidence on the existence and effects of 'credit rationing' in the context of developing countries. This is the contribution of the current paper. Using a survey of 4,553 entrepreneurs in 51 slums in Rio de Janeiro, this paper uses mean and quantile regression estimates to shows the effects of the type of initial capital, credit constraints, and human capital factors on entrepreneurs' performance. The main findings of the the paper are that entrepreneurs that were able to self-finance their business start-up presented earnings 16% greater than entrepreneurs that had to borrow their initial capital. In addition, entrepreneurs that explicitly claimed to be credit constrained performed substantially worse than their observationally identical counterparts, even if they were credit worthy. Both, initial source of funding and liquidity constraint presented greater effects on the highest quantiles. In terms of human capital, the current study shows positive and statistically significant returns for both years of schooling and experience, with higher returns on the lowest quantiles, indicating the potential role of these factors on inequality reduction.

General relativistic hydrodynamics in curvilinear coordinates

In this paper we report on what we believe is the first successful implementation of relativistic hydrodynamics, coupled to dynamical spacetimes, in spherical polar coordinates without symmetry assumptions. We employ a high-resolution shock-capturing scheme, which requires that the equations be cast in flux-conservative form. One example of such a form is the :Valencia" formulation, which has been adopted in numerous applications, in particular in Cartesian coordinates. Here we generalize this formulation to allow for a reference-metric approach, which provides a natural framework for calculations in curvilinear coordinates. In spherical polar coordinates, for example, it allows for an analytical treatment of the singular r and sin(\theta) terms that appear in the equations. We experiment with different versions of our generalized Valencia formulation in numerical implementations of relativistic hydrodynamics for both fixed and dynamical spacetimes. We consider a number of different tests -- non-rotating and rotating relativistic stars, as well as gravitational collapse to a black hole -- to demonstrate that our formulation provides a promising approach to performing fully relativistic astrophysics simulations in spherical polar coordinates.Comment: 14 pages, 8 figures, version to be published in PR

Numerical Relativity in Spherical Polar Coordinates: Off-center Simulations

We have recently presented a new approach for numerical relativity simulations in spherical polar coordinates, both for vacuum and for relativistic hydrodynamics. Our approach is based on a reference-metric formulation of the BSSN equations, a factoring of all tensor components, as well as a partially implicit Runge-Kutta method, and does not rely on a regularization of the equations, nor does it make any assumptions about the symmetry across the origin. In order to demonstrate this feature we present here several off-centered simulations, including simulations of single black holes and neutron stars whose center is placed away from the origin of the coordinate system, as well as the asymmetric head-on collision of two black holes. We also revisit our implementation of relativistic hydrodynamics and demonstrate that a reference-metric formulation of hydrodynamics together with a factoring of all tensor components avoids problems related to the coordinate singularities at the origin and on the axes. As a particularly demanding test we present results for a shock wave propagating through the origin of the spherical polar coordinate system.Comment: 13 pages, 11 figures; matches version published in PR

THE EFFECTS OF SECTORAL AND ECONOMY-WIDE POLICIES ON TOBACCO PRODUCTION IN THE DOMINICAN REPUBLIC

This study analyses the effects of specific agricultural and exchange rate policies on tobacco production in the Dominican Republic. Direct protection resulting from output and input subsidies and taxes was positive on average from 1966 to 1988, but total protection was negative when exchange rate policies are considered. Tobacco policies were quite volatile and resulted in increasing production in the 1970s but decreasing production in the 1980s. Overall, tobacco production was 4.8 percent less than it would have been had there been no policy interventions. Several reasons are provided for the policies.Dominican Republic, Nominal rate of protection, Tobacco policies, Agricultural and Food Policy, Production Economics,