Quantum chaos with non-periodic, complex orbits in the Resonant Tunneling Diode

We show that a special type of orbits, which are non-periodic and complex, 'Saddle Orbits' (SOs) describe accurately the quantal and experimental current oscillations in the Resonant Tunneling Diode in tilted fields. This is the first demonstration that one needs to abandon the periodic orbits (POs) paradigm in favour of this new and peculiar type of orbit. The SOs solve the puzzle of broad regions of experimental oscillations where we find no real or complex PO that can explain the data. The SOs succeeds in regimes involving several non-isolated POs, where PO formulas fail.Comment: 3 pages, 5 figure

The possibility of determining open-cluster parameters from BVRI photometry

In the last decades we witnessed an increase in studies of open clusters of the Galaxy, especially because of the good determination for a wide range of values of parameters such as age, distance, reddening, and proper motion. The reliable determination of the parameters strongly depends on the photometry available and especially on the U filter, which is used to obtain the color excess E(B-V) through the color-color diagram (U-B) by (B-V) by fitting a zero age main-sequence. Owing to the difficulty of performing photometry in the U band, many authors have tried to obtain E(B-V) without the filter. But because of the near linearity of the color-color diagrams that use the other bands, combined with the fact that most fitting procedures are highly subjective (many done "by eye") the reliability of those results has always been questioned. Our group has recently developed, a tool that performs isochrone fitting in open-cluster photometric data with a global optimization algorithm, which removes the need to visually perform the fits and thus removes most of the related subjectivity. Here we apply our method to a set of synthetic clusters and two observed open clusters (Trumpler 1 and Melotte 105) using only photometry for the BVRI bands. Our results show that, considering the cluster structural variance caused only by photometric and Poisson sampling errors, our method is able to recover the synthetic cluster parameters with errors of less than 10% for a wide range of ages, distances, and reddening, which clearly demonstrates its potential. The results obtained for Trumpler 1 and Melotte 105 also agree well with previous literature values.Comment: 5 pages, 5 figures, accepted for publication in Astronomy&Astrophysic

Tuning the Mott transition in a Bose-Einstein condensate by multi-photon absorption

We study the time-dependent dynamics of a Bose-Einstein condensate trapped in an optical lattice. Modeling the system as a Bose-Hubbard model, we show how applying a periodic driving field can induce coherent destruction of tunneling. In the low-frequency regime, we obtain the novel result that the destruction of tunneling displays extremely sharp peaks when the driving frequency is resonant with the depth of the trapping potential (``multi-photon resonances''), which allows the quantum phase transition between the Mott insulator and the superfluid state to be controlled with high precision. We further show how the waveform of the field can be chosen to maximize this effect.Comment: Minor changes, this version to be published in Phys. Rev. Let

From Growth Spurts to Sustained Growth: The Nature of Growth and Unified Growth Theory

The recent literature on unified growth theory has shed new light on the transition to sustained economic growth. Nevertheless, unified growth theory has not devoted a lot of attention to the nature of economic growth and its impact in the transition from Malthus to Solow. This research presents new evidence on the existence of pre-industrial growth spurts and provides new foundations concerning the nature of economic growth during the Malthus to Solow transition. Following previous research in unified growth theory, sustained economic growth arises due to complementarities between the triple engines of growth of technological development, human capital and the organization of the workplace. In this research, growth spurts are an intrinsic feature of the economy, but throughout history their effect on standards of living is mostly temporary. The rise in living standards only becomes sustained when the complementarity of the triple engines of growth emerges. In Malthusian economies, most technologies were basic and only require straightforward knowledge or human capital, and thus the skill-technology complementarity did not play a role in their development. As a consequence, most technological developments in Malthusian economies generated growth spurts that did not become sustained, although there was a temporary increase in standards of living. However, the increasing complexity of the epistemic knowledge base reported by the historical literature meant that investments in applied technology were progressively more significant, enhancing the role of human capital. After a certain threshold of the knowledge base was surpassed, more and more complex applied technologies were developed, and growth spurts became permanent features of the economy. This research thus captures some of the most important historical features concerning the nature of growth in the transition to sustained economic growth.growth spurts, unified growth theory, sustained economic growth

Update of membership and mean proper motion of open clusters from UCAC5 catalog

We present mean proper motions and membership probabilities of individual stars for optically visible open clusters, which have been determined using data from the UCAC5 catalog. This follows our previous studies with the UCAC2 and UCAC4 catalogs, but now using improved proper motions in the GAIA reference frame. In the present study results were obtained for a sample of 1108 open clusters. For five clusters, this is the first determination of mean proper motion, and for the whole sample, we present results with a much larger number of identified astrometric member stars than on previous studies. It is the last update of our Open cluster Catalog based on proper motion data only. Future updates will count on astrometric, photometric and spectroscopic GAIA data as input for analyses.Comment: 7 pages, 3 figures, 2 tables, 4 equations; accepted for publication in 2018 May 25 in the MNRA