3,281 research outputs found
Global imbalances and developing countries.
The main distinguishing features of present-day global imbalances go beyond their sheer amount and generalisation. First, the world economy is characterised by an increased and dynamic presence of many developing countries that simultaneously have turned from deficit into surplus economies. Second, imbalances happen in a context of variable exchange rates and under an accelerated process of financial globalisation. Third, the international reserve currency is basically the currency of just one advanced country in the world. Both the variability of exchange rates –in principle freeing countries of the need to defend their parities–and the easy availability of private foreign finance –liberating them from the limits imposed either by the amount of foreign exchange reserves or the conditional access to IMF resources– go to a great extent to explain the increase and generalisation of current account deficits. But, additionally, the capacity of the United States to run deficits financed by the fact of their issuing the international reserve currency, has decisively contributed to the explosion in the magnitude of the imbalances. Of course, the ability to finance deficits by resorting to foreign inflows is dominated by its variability and by the accumulation of debt frequently ending up in severe crises. Thus, financial stability is endangered. On the surpluses side, quite a few major advanced countries persist in generating them instead of promoting fast rates of growth and improving the lot of their own citizens. Thus, the old-time deflationary bias that places limits on deficit countries while leaving the major surplus countries to unfettered run restrictive policies playing beggar-thy-neighbour on the rest of the world still rules the present-day non-system. Surely, many fast growing developing countries, having on the contrary become the dynamic force in the world economy, play a completely different role based on their having overcome the restrictions that deficits used to place on their performance. Redressing global imbalances to avoid financial instability, therefore, would, at the international level, require regulating “speculative” private international capital flows, on the one hand, and devising a new international monetary system that would run on the basis of a multilateral reserve currency. Additionally, a less restrictive mechanism than the conditionality-run IMF should be established for clearing temporary imbalances with similar obligations for surplus and deficit countries, although growth rates and the stage of development would have to be taken into account. Redressing global imbalances, however, should not be made at the expense of growth in the world economy that as mentioned before has come to increasingly depend on the developing countries’ economies. Room, therefore, would have to be built for the surpluses of the developing countries following successful export-led strategies to be accommodated within such a system. This way, developing countries will keep being able to pursue expansionary policies, reduce inequality and continue to represent a dynamic force in global terms.
Electron-correlation driven capture and release in double quantum dots
We recently predicted that the interatomic Coulombic electron capture (ICEC)
process, a long-range electron correlation driven capture process, is
achievable in gated double quantum dots (DQDs). In ICEC an incoming electron is
captured by one QD and the excess energy is used to remove an electron from the
neighboring QD. In this work we present systematic full three-dimensional
electron dynamics calculations in quasi-one dimensional model potentials that
allow for a detailed understanding of the connection between the DQD geometry
and the reaction probability for the ICEC process. We derive an effective
one-dimensional approach and show that its results compare very well with those
obtained using the full three-dimensional calculations. This approach
substantially reduces the computation times. The investigation of the
electronic structure for various DQD geometries for which the ICEC process can
take place clarify the origin of its remarkably high probability in the
presence of two-electron resonances
Controlled energy-selected electron capture and release in double quantum dots
Highly accurate quantum electron dynamics calculations demonstrate that
energy can be efficiently transferred between quantum dots. Specifically, in a
double quantum dot an incoming electron is captured by one dot and the excess
energy is transferred to the neighboring dot and used to remove an electron
from this dot. This process is due to long-range electron correlation and shown
to be operative at rather large distances between the dots. The efficiency of
the process is greatly enhanced by preparing the double quantum dot such that
the incoming electron is initially captured by a two-electron resonance state
of the system. In contrast to atoms and molecules in nature, double quantum
dots can be manipulated to achieve this enhancement. This mechanism leads to a
surprisingly narrow distribution of the energy of the electron removed in the
process which is explained by resonance theory. We argue that the process could
be exploited in practice.Comment: Lette
A transiting planet among 23 new near-threshold candidates from the OGLE survey - OGLE-TR-182
By re-processing the data of the second season of the OGLE survey for
planetary transits and adding new mesurements on the same fields gathered in
subsequent years with the OGLE telescope, we have identified 23 new transit
candidates, recorded as OGLE-TR-178 to OGLE-TR-200. We studied the nature of
these objects with the FLAMES/UVES multi-fiber spectrograph on the VLT. One of
the candidates, OGLE-TR-182, was confirmed as a transiting gas giant planet on
a 4-day orbit. We characterised it with further observations using the FORS1
camera and UVES spectrograph on the VLT. OGLE-TR-182b is a typical ``hot
Jupiter'' with an orbital period of 3.98 days, a mass of 1.01 +- 0.15 MJup and
a radius of 1.13 (+0.24-0.08) RJup. Confirming this transiting planet required
a large investment in telescope time with the best instruments available, and
we comment on the difficulty of the confirmation process for transiting planets
in the OGLE survey. We delienate the zone were confirmation is difficult or
impossible, and discuss the implications for the Corot space mission in its
quest for transiting telluric planets.Comment: 7 pages, submitted to Astronomy and Astrophysic
Exact finite reduced density matrix and von Neumann entropy for the Calogero model
The information content of continuous quantum variables systems is usually
studied using a number of well known approximation methods. The approximations
are made to obtain the spectrum, eigenfunctions or the reduced density matrices
that are essential to calculate the entropy-like quantities that quantify the
information. Even in the sparse cases where the spectrum and eigenfunctions are
exactly known the entanglement spectrum, {\em i.e.} the spectrum of the reduced
density matrices that characterize the problem, must be obtained in an
approximate fashion. In this work, we obtain analytically a finite
representation of the reduced density matrices of the fundamental state of the
N-particle Calogero model for a discrete set of values of the interaction
parameter. As a consequence, the exact entanglement spectrum and von Neumann
entropy is worked out.Comment: Journal of Physics A (in press
Detection and discrimination between ochratoxin producer and non-producer strains of Penicillium nordicum on a ham-based medium using an electronic nose
The aim of this work was to evaluate the potential use of qualitative volatile
patterns produced by Penicillium nordicum to discriminate between ochratoxin A
(OTA) producers and non-producer strains on a ham-based medium. Experiments were
carried out on a 3% ham medium at two water activities (aw ; 0.995, 0.95)
inoculated with P. nordicum spores and incubated at 25°C for up to 14days.
Growing colonies were sampled after 1, 2, 3, 7 and 14days, placed in 30-ml
vials, sealed and the head space analysed using a hybrid sensor electronic nose
device. The effect of environmental conditions on growth and OTA production was
evaluated based on the qualitative response. However, after 7days, it was
possible to discriminate between strains grown at 0.995 aw, and after 14days,
the OTA producer and non-producer strain and the controls could be discriminated
at both aw levels. This study suggests that volatile patterns produced by P.
nordicum strains may differ and be used to predict the presence of toxigenic
contaminants in ham. This approach could be utilised in ham production as part
of a quality assurance system for preventing OTA contaminatio
OGLE-TR-211 - a new transiting inflated hot Jupiter from the OGLE survey and ESO LP666 spectroscopic follow-up program
We present results of the photometric campaign for planetary and
low-luminosity object transits conducted by the OGLE survey in 2005 season
(Campaign #5). About twenty most promising candidates discovered in these data
were subsequently verified spectroscopically with the VLT/FLAMES spectrograph.
One of the candidates, OGLE-TR-211, reveals clear changes of radial velocity
with small amplitude of 82 m/sec, varying in phase with photometric transit
ephemeris. Thus, we confirm the planetary nature of the OGLE-TR-211 system.
Follow-up precise photometry of OGLE-TR-211 with VLT/FORS together with radial
velocity spectroscopy supplemented with high resolution, high S/N VLT/UVES
spectra allowed us to derive parameters of the planet and host star.
OGLE-TR-211b is a hot Jupiter orbiting a F7-8 spectral type dwarf star with the
period of 3.68 days. The mass of the planet is equal to 1.03+/-0.20 M_Jup while
its radius 1.36+0.18-0.09 R_Jup. The radius is about 20% larger than the
typical radius of hot Jupiters of similar mass. OGLE-TR-211b is, then, another
example of inflated hot Jupiters - a small group of seven exoplanets with large
radii and unusually small densities - objects being a challenge to the current
models of exoplanets.Comment: 6 pages. Submitted to Astronomy and Astrophysic
Entropy, fidelity, and double orthogonality for resonance states in two-electron quantum dots
Resonance states of a two-electron quantum dot are studied using a
variational expansion with both real basis-set functions and complex scaling
methods. The two-electron entanglement (linear entropy) is calculated as a
function of the electron repulsion at both sides of the critical value, where
the ground (bound) state becomes a resonance (unbound) state. The linear
entropy and fidelity and double orthogonality functions are compared as methods
for the determination of the real part of the energy of a resonance. The
complex linear entropy of a resonance state is introduced using complex scaling
formalism
A Gaussian process framework for modelling instrumental systematics: application to transmission spectroscopy
Transmission spectroscopy, which consists of measuring the
wavelength-dependent absorption of starlight by a planet's atmosphere during a
transit, is a powerful probe of atmospheric composition. However, the expected
signal is typically orders of magnitude smaller than instrumental systematics,
and the results are crucially dependent on the treatment of the latter. In this
paper, we propose a new method to infer transit parameters in the presence of
systematic noise using Gaussian processes, a technique widely used in the
machine learning community for Bayesian regression and classification problems.
Our method makes use of auxiliary information about the state of the
instrument, but does so in a non-parametric manner, without imposing a specific
dependence of the systematics on the instrumental parameters, and naturally
allows for the correlated nature of the noise. We give an example application
of the method to archival NICMOS transmission spectroscopy of the hot Jupiter
HD 189733, which goes some way towards reconciling the controversy surrounding
this dataset in the literature. Finally, we provide an appendix giving a
general introduction to Gaussian processes for regression, in order to
encourage their application to a wider range of problems.Comment: 6 figures, 1 table, accepted for publication in MNRA
- …