15,873 research outputs found
The debt choices of the firms in Developed Countries: evidence from G-7
This study examines the main determinants that affect the firm’s debt choices. Based on a panel data of
non-financial listed firms in G-7 countries in the period 1994-2013, the study shows that the firm’s choices about
debt level are functions of several previsions over time about, on the one hand, to the firm’s characteristics and
its expected performances and, on the other hand, to the economic, financial and institutional system of country’s
reference
On asymptotic effects of boundary perturbations in exponentially shaped Josephson junctions
A parabolic integro differential operator L, suitable to describe many
phenomena in various physical fields, is considered. By means of equivalence
between L and the third order equation describing the evolution inside an
exponentially shaped Josephson junction (ESJJ), an asymptotic analysis for
(ESJJ) is achieved, explicitly evaluating, boundary contributions related to
the Dirichlet problem
Entanglement, BEC, and superfluid-like behavior of two-mode photon systems
A system of two interacting photon modes, without constraints on the photon
number, in the presence of a Kerr nonlinearity, exhibits BEC if the transfer
amplitude is greater than the mode frequency. A symmetry-breaking field (SBF)
can be introduced by taking into account a classical electron current. The
ground state, in the limit of small nonlinearity, becomes a squeezed state, and
thus the modes become entangled. The smaller is the SBF, the greater is
entanglement. Superfluid-like behavior is observed in the study of entanglement
growth from an initial coherent state, since in the short-time range the growth
does not depend on the SBF amplitude, and on the initial state amplitude. On
the other hand, the latter is the only parameter which determines entanglement
in the absence of the SBF
Two-spin entanglement induced by electron scattering in nanostructures
We present a model where two magnetic impurities in a discrete tight-binding
ring become entangled because of scattering processes associated to the
injection of a conduction electron. We introduce a weak coupling approximation
that allows us to solve the problem in a analytical way and compare the theory
with the exact numerical results. We obtain the generation of entanglement both
in a deterministic way and in a probabilistic one. The first case is
intrinsically related to the structure of the two-impurity reduced density
matrix, while the second one occurs when a projection on the electron state is
performed
Degradation of Entanglement in Markovian Noise
The entanglement survival time is defined as the maximum time a system which
is evolving under the action of local Markovian, homogenous in time noise, is
capable to preserve the entanglement it had at the beginning of the temporal
evolution. In this paper we study how this quantity is affected by the
interplay between the coherent preserving and dissipative contributions of the
corresponding dynamical generator. We report the presence of a
counterintuitive, non-monotonic behaviour in such functional, capable of
inducing sudden death of entanglement in models which, in the absence of
unitary driving are capable to sustain entanglement for arbitrarily long times.Comment: 15 pages, 5 figure
A systematic analysis of X-ray afterglows of gamma-ray burst observed by XMM-Newton
This work is part of a systematic re-analysis program of all the data of
Gamma-Ray Burst (GRB) X-ray afterglows observed so far, in order to constrain
the GRB models. We present here a systematic analysis of those afterglows
observed by XMM-Newton between January 2000 and March 2004. This dataset
includes GRB 011211 and GRB 030329. We have obtained spectra, light curves and
colors for these afterglows. In this paper we focus on the continuum spectral
and temporal behavior. We compare these values with the theoretical ones
expected from the fireball model. We derive constraints about the burst
environment (absorption, density profile) and put constraints on their beaming
angle.Comment: 7 pages, 2 figures, COSPAR proceeding accepted for publication in
Advances in Space Researc
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