Aharonov-Bohm oscillations and resonant tunneling in strongly correlated quantum dots

We investigate Aharonov-Bohm oscillations of the current through a strongly correlated quantum dot embedded in an arbitrary scattering geometry. Resonant-tunneling processes lead to a flux-dependent renormalization of the dot level. As a consequence we obtain a fine structure of the current oscillations which is controlled by quantum fluctuations. Strong Coulomb repulsion leads to a continuous bias voltage dependent phase shift and, in the nonlinear response regime, destroys the symmetry of the differential conductance under a sign change of the external flux.Comment: RevTex, 5 pages, 3 PostScript figures. Accepted for publication in Phys. Rev. Let

Solid-State Quantum Communication With Josephson Arrays

Josephson junction arrays can be used as quantum channels to transfer quantum information between distant sites. In this work we discuss simple protocols to realize state transfer with high fidelity. The channels do not require complicate gating but use the natural dynamics of a properly designed array. We investigate the influence of static disorder both in the Josephson energies and in the coupling to the background gate charges, as well as the effect of dynamical noise. We also analyze the readout process, and its backaction on the state transfer

The Impact of Fiscal Restraint on Budgetary Allocations for Women's Programs

How did the fiscal restraints exercised during the time of fiscal difficulties in 1997-2003 affect the gender/women-targeted programs of the Philippine government? What does a close scrutiny of the government budget reveal regarding the implicit gender implications of such restraints? Manasan and Villanueva disclose some of their findings.budget analysis, gender analysis, women's programs

Looking Closely on Who Benefits from Public Subsidies in Health Care: a Gender Perspective

Do men benefit more than women from government expenditures in health care? Or do women have the upper hand? Using a sex-differentiated incidence analysis of the various Department of Health program expenditures, this Notes' authors assess who indeed benefits from such expenditures in terms of gender. And why.gender, benefit incidence analysis, gender analysis, public spending in health, sex-differentiated incidence analysis

Anomalous density of states of a Luttinger liquid in contact with a superconductor

We study the frequency and space dependence of the local tunneling density of states of a Luttinger liquid (LL) which is connected to a superconductor. This coupling {\em strongly} modifies the single-particle properties of the LL. It significantly enhances the density of states near the Fermi level, whereas this quantity vanishes as a power law for an isolated LL. The enhancement is due to the interplay between electron-electron interactions and multiple back-scattering processes of low-energy electrons at the interface between the LL and the superconductor. This anomalous behavior extends over large distances from the interface and may be detected by coupling normal probes to the system.Comment: 8 pages Revtex, two postscript figure

Relations between entanglement and purity in non-Markovian dynamics

Knowledge of the relationships among different features of quantumness, like entanglement and state purity, is important from both fundamental and practical viewpoints. Yet, this issue remains little explored in dynamical contexts for open quantum systems. We address this problem by studying the dynamics of entanglement and purity for two-qubit systems using paradigmatic models of radiation-matter interaction, with a qubit being isolated from the environment (spectator configuration). We show the effects of the corresponding local quantum channels on an initial two-qubit pure entangled state in the concurrence-purity diagram and find the conditions which enable dynamical closed formulas of concurrence, used to quantify entanglement, as a function of purity. We finally discuss the usefulness of these relations in assessing entanglement and purity thresholds which allow noisy quantum teleportation. Our results provide new insights about how different properties of composite open quantum systems behave and relate each other during quantum evolutions.Comment: 16 Pages, 10 Figures. One author added. Improved version with more references and comment

The Nuclear Outflow in NGC 2110

We present a HST/STIS spectroscopic and optical/radio imaging study of the Seyfert NGC 2110 aiming to measure the dynamics and understand the nature of the nuclear outflow in the galaxy. Previous HST studies have revealed the presence of a linear structure in the Narrow-Line Region (NLR) aligned with the radio jet. We show that this structure is strongly accelerated, probably by the jet, but is unlikely to be entrained in the jet flow. The ionisation properties of this structure are consistent with photoionisation of dusty, dense gas by the active nucleus. We present a plausible geometrical model for the NLR, bringing together various components of the nuclear environment of the galaxy. We highlight the importance of the circum-nuclear disc in determining the appearance of the emission line gas and the morphology of the jet. From the dynamics of the emission line gas, we place constraints on the accelerating mechanism of the outflow and discuss the relative importance of radio source synchrotron pressure, radio jet ram pressure and nuclear radiation pressure in accelerating the gas. While all three mechanisms can account for the energetics of the emission line gas, gravitational arguments support radio jet ram pressure as the most likely source of the outflow.Comment: 15 pages, 7 figures; accepted to MNRA

An Empirical Investigation of Debt Contract Design: The Determinants of the Choice of Debt Terms in Eurobond Issues

This paper provides a comprehensive analysis of the determinants for the optimal choice of contract terms on Eurobonds issued by UK companies. We examine predictions of extant theories that associate the choice of debt features namely, maturity, call options, convertible options, and protective covenants to firm and market characteristics. Like in Correia (2003), a simultaneous equations approach is adopted to test the alternative use of contract features for mitigating debt-contracting costs. The evidence provides strong support to the prediction that both callable and short-term debt and convertible and debt with protective covenants are used as alternative control devises to mitigate agency costs. Further evidence suggests, however, that contrary to the fundamentals guiding the choice of maturity and callability structures, the use of conversion options and protective covenants in Eurobond contracts seems to be determined by equity agency costs rather than debt agency costs. Also, some support is found for the risk uncertainty theory underlying the use of convertibles and for liquidity risk arguments regarding the choice to include protective covenants.