Numerical simulation of dark lanes in post-flare supra-arcade

We integrate the MHD ideal equations to simulate dark void sunwardly moving structures in post--flare supra--arcades. We study the onset and evolution of the internal plasma instability to compare with observations and to gain insight into physical processes and characteristic parameters of these phenomena. The numerical approach uses a finite-volume Harten-Yee TVD scheme to integrate the 1D1/2 MHD equations specially designed to capture supersonic flow discontinuities. The integration is performed in both directions, the sunward radial one and the transverse to the magnetic field. For the first time, we numerically reproduce observational dark voids described in Verwichte et al. (2005). We show that the dark tracks are plasma vacuums generated by the bouncing and interfering of shocks and expansion waves, upstream an initial slow magnetoacoustic shock produced by a localized deposition of energy modeled with a pressure perturbation. The same pressure perturbation produces a transverse to the field or perpendicular magnetic shock giving rise to nonlinear waves that compose the kink--like plasma void structures, with the same functional sunward decreasing phase speed and constancy with height of the period, as those determined by the observations.Comment: Accepted MNRAS, 6 pages, 7 figure

Multilateral Safety Nets for Financial Crises

There is an increasing need for a system of international lending of last resort (ILLR) to provide a safety net in the event of financial crises in vulnerable countries as financial globalization deepens and spreads. Multilateral progress to address liquidity and solvency crises has been patchy and inconsistent, with no clear distinction between the two; in particular, there is still no framework to address sovereign debt restructuring. This paper proposes an integrated system of specialized ILLR facilities to address problems of liquidity, adjustment, and debt restructuring in a focused but robust way as crises evolve and morph, structured in tiers to cater to countries capacity to prequalify for automatic support. It further proposes feasible legal reform to subject creditors to standstills and seniority dilution as in domestic bankruptcy in order to empower ILLR to facilitate orderly workouts in debt restructuring. Multilateral development banks would play important supporting roles

Chapter Machine Learning Techniques to Mitigate Nonlinear Phase Noise in Moderate Baud Rate Optical Communication Systems

Nonlinear phase noise (NLPN) is the most common impairment that degrades the performance of radio-over-fiber networks. The effect of NLPN in the constellation diagram consists of a shape distortion of symbols that increases the symbol error rate due to symbol overlapping when using a conventional demodulation grid. Symbol shape characterization was obtained experimentally at a moderate baud rate (250 MBd) for constellations impaired by phase noise due to a mismatch between the optical carrier and the transmitted radio frequency signal. Machine learning algorithms have become a powerful tool to perform monitoring and to identify and mitigate distortions introduced in both the electrical and optical domains. Clustering-based demodulation assisted with Voronoi contours enables the definition of non-Gaussian boundaries to provide flexible demodulation of 16-QAM and 4+12 PSK modulation formats. Phase-offset and in-phase and quadrature imbalance may be detected on the received constellation and compensated by applying thresholding boundaries obtained from impairment characterization through statistical analysis. Experimental results show increased tolerance to the optical signal-to-noise ratio (OSNR) obtained from clustering methods based on k-means and fuzzy c-means Gustafson-Kessel algorithms. Improvements of 3.2 dB for 16-QAM, and 1.4 dB for 4+12 PSK in the OSNR scale as a function of the bit error rate are obtained without requiring additional compensation algorithms

Absence of Fragmentation in Two-Dimensional Bose-Einstein Condensation

We investigate the possibility that the BEC-like phenomena recently detected on two-dimensional finite trapped systems consist of fragmented condensates. We derive and diagonalize the one-body density matrix of a two-dimensional isotropically trapped Bose gas at finite temperature. For the ideal gas, the procedure reproduces the exact harmonic-oscillator eigenfunctions and the Bose distribution. We use a new collocation-minimization method to study the interacting gas in the Hartree-Fock approximation and obtain a ground-state wavefunction and condensate fraction consistent with those obtained by other methods. The populations of the next few eigenstates increase at the expense of the ground state but continue to be negligible; this supports the conclusion that two-dimensional BEC is into a single state.Comment: 6 pages, 1 figur

Controlling crystallization and its absence: Proteins, colloids and patchy models

The ability to control the crystallization behaviour (including its absence) of particles, be they biomolecules such as globular proteins, inorganic colloids, nanoparticles, or metal atoms in an alloy, is of both fundamental and technological importance. Much can be learnt from the exquisite control that biological systems exert over the behaviour of proteins, where protein crystallization and aggregation are generally suppressed, but where in particular instances complex crystalline assemblies can be formed that have a functional purpose. We also explore the insights that can be obtained from computational modelling, focussing on the subtle interplay between the interparticle interactions, the preferred local order and the resulting crystallization kinetics. In particular, we highlight the role played by ``frustration'', where there is an incompatibility between the preferred local order and the global crystalline order, using examples from atomic glass formers and model anisotropic particles.Comment: 11 pages, 7 figure

Household Labor Supply and Home Services in a General-Equilibrium Model with Heterogeneous Agents

We propose a new explanation for differences and changes in labor supply by gender and marital status, and in particular for the increase in married women's labor supply over time. We argue that this increase as well as the relative constancy of other groups' hours are optimal reactions to outsourcing labor in home production becoming more attractive to households over time. To investigate this hypothesis, we incorporate heterogeneous agents into a household model of labor supply and allow agents to trade home labor. This model can generate the observed patterns in US labor supply by gender and marital status as a reaction to declining frictions on the market for home services. We provide an accounting exercise to highlight the role of alternative explanations for the rise in hours in a model where home labor is tradable

Plan de negocios para implementar una empresa dedicada al factoring, utilizando tecnolog?a financiera (Fintech) y orientada a MIPYMES principalmente de Arequipa

El presente plan de negocios busca identificar la viabilidad de la implementaci?n de una empresa dedicada al factoring para MIPYMES en la ciudad de Arequipa, bas?ndose en la utilizaci?n de una plataforma virtual que permita una interacci?n entre los involucrados y asegure la efectividad de las diversas operaciones que se dar?n, as? como el asesoramiento directo de ejecutivos de negocio. La informaci?n secundaria de este proyecto se obtuvo de fuentes como PRODUCE, Cavali, INEI, entre otros; mientras que la informaci?n primaria, fue resultado de entrevistas a expertos y encuestas a una muestra de MIPYMES bancarizadas de Arequipa; todo esto como parte del estudio de mercado realizado. Adicionalmente, se ha desarrollado el an?lisis estrat?gico, el plan de marketing, la pol?tica funcional y finalmente la evaluaci?n econ?mica y financiera; esta ?ltima mostrando resultados muy optimistas sobre la viabilidad de este negocio. Para complementar, se realiz? el an?lisis de sensibilidad respectivo para visualizar las variables que m?s afectan al modelo. En retrospectiva, se observ? que el ?xito del modelo de negocio radica en la diferenciaci?n del servicio. Para lograr esto es necesario ofrecer un servicio innovador enfocado en un nicho de mercado desatendido (MIPYMES bancarizadas en Arequipa) aplicando un plan de marketing agresivo

Dynamic Provisioning: Some Lessons from Existing Experiences

After analyzing the different reasons why the financial system and also the regulatory framework induced procyclicality, this paper reviews the experiences of three countries which have introduced dynamic provisioning as a regulatory tool to limit procyclicality. The case of Spain - the country with the longest experience - is reviewed, as well as those of Colombia and Peru - countries that have recently adopted dynamic provisioning. A number of policy lessons are drawn from that comparison

Health Outcome Predictive Evaluation for COVID 19 international registry (HOPE COVID-19), rationale and design

The disease produced by the new coronavirus known as SARS-CoV-2 (Severe Acute Respiratory Syndrome Coronavirus 2), named COVID-19 (Coronavirus Disease-2019) has recently been classified as a pandemic by the World Health Organization (WHO). However, scarce clinical data is available and generally limited to the Chinese population due to the first cases were identified in Wuhan (Hubei, China).This article describes the rationale and design of the HOPE COVID-19 (Health Outcome Predictive Evaluation for COVID 19) registry (ClinicalTrials.gov Identifier: NCT04334291). With an ambispective cohort design, eligible patients are those discharged, deceased or alive, from any hospital center with a confirmed diagnosis or a COVID-19 high suspicion. With a current recruitment of more than 7000 cases, in 46 hospitals in 8 countries, since it is not possible to estimate the sample size based on literature reports, the investigators will try to get the maximum numbers of patients possible. The study primary objective is all cause mortality and aims to characterize the clinical profile of patients infected in order to develop a prognostic clinical score allowing, rapid logistic decision making. As secondary objectives, the analysis of other clinical events, the risk-adjusted influence of treatments and previous comorbidities of patients infected with the disease will be performed.The results of HOPE COVID-19 will contribute to a better understanding of this condition. We aim to describe the management of this condition as well as the outcomes in relation to the therapy chosen, in order to gain insight into improving patient care in the coming months. Clinical Trial registration: ClinicalTrials.gov. Unique identifier: NCT04334291