Analytical Potentials for Flat Galaxies with Spheroidal Halos

A family of analytical potential-density pairs for flat galaxies with spheroidal halos is presented. The potential are obtained by means of the sum of two independent terms: a potential associated with a thin disc and a potential associated with a spheroidal halo, which are expressed as appropriated superpositions of products of Legendre functions, in such a way that the model implies a linear relationship between the masses of the thin disc and the spheroidal halo. By taking a particular case for the halo potential, we found that the circular velocity obtained can be adjusted very accurately to the observed rotation curves of some specific galaxies, so that the models are stable against radial and vertical perturbations. Two particular models for the galaxies NGC4389 and UGC6969 are obtained by adjusting the circular velocity with data of the observed rotation curve of some galaxies of the Ursa Mayor Cluster, as reported in Verheijen and Sancisi 2001. The values of the halo mass and the disc mass for these two galaxies are computed obtaining a very narrow interval of values for these quantities. Furthermore, the values of obtained masses are in perfect agreement with the expected order of magnitude and with the relative order of magnitude between the halo mass and the disc mass.Comment: 13 pages, 3 tables, 7 figures. Updated version published at Revista de la Academia Colombiana de Ciencias Exactas F\'isicas y Matem\'atica

Formation of Nanotwin Networks during High-Temperature Crystallization of Amorphous Germanium

Germanium is an extremely important material used for numerous functional applications in many fields of nanotechnology. In this paper, we study the crystallization of amorphous Ge using atomistic simulations of critical nano-metric nuclei at high temperatures. We find that crystallization occurs by the recurrent transfer of atoms via a diffusive process from the amorphous phase into suitably-oriented crystalline layers. We accompany our simulations with a comprehensive thermodynamic and kinetic analysis of the growth process, which explains the energy balance and the interfacial growth velocities governing grain growth. For the $\langle111\rangle$ crystallographic orientation, we find a degenerate atomic rearrangement process, with two zero-energy modes corresponding to a perfect crystalline structure and the formation of a $\Sigma3$ twin boundary. Continued growth in this direction results in the development a twin network, in contrast with all other growth orientations, where the crystal grows defect-free. This particular mechanism of crystallization from amorphous phases is also observed during solid-phase epitaxial growth of $\langle111\rangle$ semiconductor crystals, where growth is restrained to one dimension. We calculate the equivalent X-ray diffraction pattern of the obtained nanotwin networks, providing grounds for experimental validation

2D granular flows with the μ(I)\mu(I) rheology and side walls friction: a well balanced multilayer discretization

We present here numerical modelling of granular flows with the $\mu(I)$ rheology in confined channels. The contribution is twofold: (i) a model to approximate the Navier-Stokes equations with the $\mu(I)$ rheology through an asymptotic analysis. Under the hypothesis of a one-dimensional flow, this model takes into account side walls friction; (ii) a multilayer discretization following Fern\'andez-Nieto et al. (J. Fluid Mech., vol. 798, 2016, pp. 643-681). In this new numerical scheme, we propose an appropriate treatment of the rheological terms through a hydrostatic reconstruction which allows this scheme to be well-balanced and therefore to deal with dry areas. Based on academic tests, we first evaluate the influence of the width of the channel on the normal profiles of the downslope velocity thanks to the multilayer approach that is intrinsically able to describe changes from Bagnold to S-shaped (and vice versa) velocity profiles. We also check the well balance property of the proposed numerical scheme. We show that approximating side walls friction using single-layer models may lead to strong errors. Secondly, we compare the numerical results with experimental data on granular collapses. We show that the proposed scheme allows us to qualitatively reproduce the deposit in the case of a rigid bed (i. e. dry area) and that the error made by replacing the dry area by a small layer of material may be large if this layer is not thin enough. The proposed model is also able to reproduce the time evolution of the free surface and of the flow/no-flow interface. In addition, it reproduces the effect of erosion for granular flows over initially static material lying on the bed. This is possible when using a variable friction coefficient $\mu(I)$ but not with a constant friction coefficient

Total correlations as fully additive entanglement monotones

We generalize the strategy presented in Refs. [1, 2], and propose general conditions for a measure of total correlations to be an entanglement monotone using its pure (and mixed) convex-roof extension. In so doing, we derive crucial theorems and propose a concrete candidate for a total correlations measure which is a fully additive entanglement monotone.Comment: 8 pages, 3 figures. Title changed, new result

Risk and protective factors for release in outpatients with schizophrenia

eposterWe aim to determine risk and protective factors influencing relapse incidence in outpatient with schizophrenia. A longitudinal, observational study was done with outpatients with schizophrenia (F20) or schizoaffective disorder (F25)(DMS-IV and ICD-10), without hospitalization during the previous 6 months. The patients were consecutively included into the study to received oral (O-A) or long-acting injectable (depot-A) antipsychotics. Clinical stage evolution, compliance, efficacy and safety assessments (including PANSS, CGI-SSI, hospitalization rates, and adverse events) were recorded before and after 6 and 12 months of treatment. Results: 60 outpatients (aged 34.5±8.9, male 73%), 75% schizophrenia and 25% schizoaffective disorder diagnosis, 68.3% fewer than 15 years of schizophrenia evolution, 76.7% fewer than 5 times previous hospitalizations were treated with O-A (41.7%) or depot-A (58.3%) antipsychotics for at least one year. Depot-A treated patients showed a significant higher compliance compared to O-A patients during the all following time, lower PANSS (total, positive and negative) scores and CGI-SSI score (p<0.01), and a delayed relapse incidence and re-hospitalization to more than 1 year in the 48% of patients (relapse % depot/% oral) after 6 months 22.9%/52.0%, and after 12 months 48.6%/4.0%. Conclusion: There were protective factors which delayed relapse incidence in schizophrenia: Use of sustained-release preparations, family support. There were risk factors for occurrence of relapse in schizophrenia: cocaine, heroin and alcohol consumption, absence of family support, greater severity of patients assessed through CGI-SI, male sex, age older than 25 years and long-term evolution of the disorder.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Correlations in optically-controlled quantum emitters

We address the problem of optically controlling and quantifying the dissipative dynamics of quantum and classical correlations in a set-up of individual quantum emitters under external laser excitation. We show that both types of correlations, the former measured by the quantum discord, are present in the system's evolution even though the emitters may exhibit an early stage disentanglement. In the absence of external laser pumping,we demonstrate analytically, for a set of suitable initial states, that there is an entropy bound for which quantum discord and entanglement of the emitters are always greater than classical correlations, thus disproving an early conjecture that classical correlations are greater than quantum correlations. Furthermore, we show that quantum correlations can also be greater than classical correlations when the system is driven by a laser field. For scenarios where the emitters' quantum correlations are below their classical counterparts, an optimization of the evolution of the quantum correlations can be carried out by appropriately tailoring the amplitude of the laser field and the emitters' dipole-dipole interaction. We stress the importance of using the entanglement of formation, rather than the concurrence, as the entanglement measure, since the latter can grow beyond the total correlations and thus give incorrect results on the actual system's degree of entanglement.Comment: 11 pages, 10 figures, this version contains minor modifications; to appear in Phys. Rev.

Enhanced gauge symmetries on elliptic K3

We show that the geometry of K3 surfaces with singularities of type A-D-E contains enough information to reconstruct a copy of the Lie algebra associated to the given Dynkin diagram. We apply this construction to explain the enhancement of symmetry in F and IIA theories compactified on singular K3's.Comment: 9 pages, Late