The scaling of the density of states in systems with resonance states

Resonance states of a two-electron quantum dot are studied using a variational expansion with both real basis-set functions and complex scaling methods. We present numerical evidence about the critical behavior of the density of states in the region where there are resonances. The critical behavior is signaled by a strong dependence of some features of the density of states with the basis-set size used to calculate it. The resonance energy and lifetime are obtained using the scaling properties of the density of statesComment: Presented in the Workshop on Quantum Nonstationary Systems (Brasilia- 2009

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

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

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.

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

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

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

Is Cosmology Solved?

We have fossil evidence from the thermal background radiation that our universe expanded from a considerably hotter denser state. We have a well defined and testable description of the expansion, the relativistic Friedmann-Lemaitre model. Its observational successes are impressive but I think hardly enough for a convincing scientific case. The lists of observational constraints and free hypotheses within the model have similar lengths. The scorecard on the search for concordant measures of the mass density parameter and the cosmological constant shows that the high density Einstein-de Sitter model is challenged, but that we cannot choose between low density models with and without a cosmological constant. That is, the relativistic model is not strongly overconstrained, the usual test of a mature theory. Work in progress will greatly improve the situation and may at last yield a compelling test. If so, and the relativistic model survives, it will close one line of research in cosmology: we will know the outlines of what happened as our universe expanded and cooled from high density. It will not end research: some of us will occupy ourselves with the details of how galaxies and other large-scale structures came to be the way they are, others with the issue of what our universe was doing before it was expanding. The former is being driven by rapid observational advances. The latter is being driven mainly by theory, but there are hints of observational guidance.Comment: 13 pages, 3 figures. To be published in PASP as part of the proceedings of the Smithsonian debate, Is Cosmology Solved