New Global Minima for Thomson's Problem of Charges on a Sphere

Using numerical arguments we find that for $N$ = 306 a tetrahedral configuration ($T_h$) and for N=542 a dihedral configuration ($D_5$) are likely the global energy minimum for Thomson's problem of minimizing the energy of $N$ unit charges on the surface of a unit conducting sphere. These would be the largest $N$ by far, outside of the icosadeltahedral series, for which a global minimum for Thomson's problem is known. We also note that the current theoretical understanding of Thomson's problem does not rule out a symmetric configuration as the global minima for N=306 and 542. We explicitly find that analogues of the tetrahedral and dihedral configurations for $N$ larger than 306 and 542, respectively, are not global minima, thus helping to confirm the theory of Dodgson and Moore (Phys. Rev. B 55, 3816 (1997)) that as $N$ grows dislocation defects can lower the lattice strain of symmetric configurations and concomitantly the energy. As well, making explicit previous work by ourselves and others, for $N<1000$ we give a full accounting of icosadeltahedral configuration which are not global minima and those which appear to be, and discuss how this listing and our results for the tetahedral and dihedral configurations may be used to refine theoretical understanding of Thomson's problem.Comment: 1- Manuscript revised. 2- A new global minimum found for a dihedral (D_5) configuration found for N=54

Pullback attractor for a dynamic boundary non-autonomous problem with Infinite delay

In this work we prove the existence of solution for a p-Laplacian non-autonomous problem with dynamic boundary and infinite delay. We ensure the existence of pullback attractor for the multivalued process associated to the non-autonomous problem we are concerned. Finally, we also prove the existence of a more general attractor for the problem known as D-pullback attractor.Conselho Nacional de Desenvolvimento Científico e TecnológicoMinisterio de Economía y CompetitividadFondo Europeo de Desarrollo RegionalJunta de Andalucí

Assessment of thermal performance and surface moisture risk for a rear-ventilated cladding system for façade renovation

Ventilated façade systems, incorporating thermal insulation behind a rear-ventilated cladding, constitute a popular renovation solution in warm European climates. For compliance with building regulations, their energy efficiency is usually obtained through simple onedimensional desktop calculations, which do not consider the impact of the support elements of the cladding penetrating the thermal insulation. This study assesses a ventilated façade system anchored over a solid concrete wall with adjustable stainless steel brackets. One-dimensional calculations are compared against three-dimensional numerical thermal modelling, evaluating the effect of insulation thickness (40–100 mm) and potential gaps in the insulation around anchors. Results indicate low risk of condensation and mould growth over internal surfaces. The additional heat flow induced by stainless steel anchors, which is not considered by simplified calculations, appears lower than for aluminium-based systems but can become significant as insulation levels increase. Ensuring the continuity of insulation around anchors is critical for keeping this additional heat flow at reasonable levels (8–13%). If gaps in the insulation are present around anchors, the additional heat flow increases substantially (25–70%) and pushes effective U-values above 0.4 W/m²K, thus resulting in unforeseen energy consumption and noncompliance with regulatory requirements in many European locations.This study has been partly developed within the InnoWEE research project. This project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 723916. The present paper reflects only the authors’ views and neither the Agency nor the Commission are responsible for any use that may be made of the information contained therein

Gobiernos y estrategias de coalición en democracias presidenciales: el caso de América Latina

La bibliografía académica sobre presidencialismo y parlamentarismo en la moderna política comparada ha sostenido que la combinación de gobierno presidencial y multipartidismo es problemática. Por supuesto, en los sistemas multipartidistas la formación de gobiernos de coalición es esencial para conseguir una mayoría legislativa. Sin embargo, las democracias parlamentarias son más estimuladoras y sostenedoras de coaliciones que los regímenes presidenciales. Los incentivos para formar y para mantener coaliciones son bastante diferentes en el residencialismo. Esto es debido a que el presidente siempre juega el papel de constructor de la coalición, el partido del presidente es normalmente un miembro necesario de la coalición y los mandatos del ejecutivo y la asamblea son predeterminados. Puesto que muchos de los países del mundo son democracias presidenciales o semi-presidenciales, intelectual y politicamente es de gran urgencia llenar el déficit de la investigación sobre gobiernos y estrategias de coalición en sistemas presidenciales multipartidistas. ¿Podemos avanzar hacia una más completa comprensión de una serie de cuestiones esenciales como los problemas de cooperación política y construcción de coaliciones en democracias presidenciales, los subtipos de gabinetes presidenciales y los ciclos de apoyo partidista para el presidente en el Congreso? Este artículo (una breve discusión de un aspecto insuficientemente estudiado del presidencialismo) intenta profundizar en el análisis centrándose en estos problemas.The scholarly literature on presidentialism and parliamentarism in modern comparative politics has argued that the combination of presidential government and a multiparty system is problematic. In multiparty systems, of course, the formation of coalition cabinets is essential for attaining a legislative majority. However, parliamentary regimes are more coalition requiring and coalition sustaining and have more coalition-building mechanisms than presidential regimes. Incentives to form and to sustain coalitions are quite different in a presidential system. This is because the president always plays the role of formateur of the coalition, the president’s party is normallly a necessary coalition partner and the terms of the executive and assembly are fixed. Since many of the countries in the world are presidential/ semi-presidential democracies, it would appear that intellectually and politically it is of the highest priority to fill the lacunae in our understanding of governments and coalition strategies under multi- party presidential systems. Can we move toward a more powerful understanding about a number of essential issues such as the problems of political cooperation and coalition building in presidential systems, as the subtypes of presidential cabinets and as cycles of party support for the president in congress? This article (a brief discussion of an as yet undertheorized aspect of presidentialism) endeavors to further the analysis by focusing on these question

A Novel Symmetric Four Dimensional Polytope Found Using Optimization Strategies Inspired by Thomson's Problem of Charges on a Sphere

Inspired by, and using methods of optimization derived from classical three dimensional electrostatics, we note a novel beautiful symmetric four dimensional polytope we have found with 80 vertices. We also describe how the method used to find this symmetric polytope, and related methods can potentially be used to find good examples for the kissing and packing problems in D dimensions

Lithium in the Hyades L5 brown dwarf 2MASS J04183483+2131275

Aims. From the luminosity, effective temperature and age of the Hyades brown dwarf 2MASS J04183483+2131275 (2M0418), substellar evolutionary models predict a mass in the range 39−55 Jupiter masses (MJup) which is insufficient to produce any substantial lithium burning except for the very upper range >53 MJup. Our goal is to measure the abundance of lithium in this object, test the consistency between models and observations and refine constraints on the mass and age of the object. Methods. We used the 10.4-m Gran Telescopio Canarias (GTC) with its low-dispersion optical spectrograph to obtain ten spectra of 2277 s each covering the range 6300–10 300 Å with a resolving power of R ~ 500. Results. In the individual spectra, which span several months, we detect persistent unresolved Hα in emission with pseudo equivalent widths (pEW) in the range 45–150 Å and absorption lines of various alkalis with the typical strengths found in objects of L5 spectral type. The lithium resonance line at 6707.8 Å is detected with pEW of 18 ± 4 Å in 2M0418 (L5). Conclusions. We determine a lithium abundance of log N(Li) = 3.0 ± 0.4 dex consistent with a minimum preservation of 90% of this element which confirms 2M0418 as a brown dwarf with a maximum mass of 52 MJup. We infer a maximum age for the Hyades of 775 Myr from a comparison with the BHAC15 models. Combining recent results from the literature with our study, we constrain the mass of 2M0418 to 45–52 MJup and the age of the cluster to 580–775 Myr (1σ) based on the lithium depletion boundary method.We thank the referee for a detailed report that improved the quality of this manuscript. This research has been supported by the Spanish Ministry of Economy and Competitiveness (MINECO) under the grants AYA2015- 69350-C3-2-P and AYA2015-69350-C3-3-P. We thank Yakiv Pavlenko for his calculations of equivalent widths at different temperatures, Isabelle Baraffe for her models, and Eduardo Martín for sharing his results prior to publication. This work is based on observations made with the Gran Telescopio Canarias (GTC), operated on the island of La Palma in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofísica de Canarias (programme GTC77- 16B led by Pérez Garrido). This research has made use of the Simbad and Vizier databases, operated at the Centre de Données Astronomiques de Strasbourg (CDS), and of NASA’s Astrophysics Data System Bibliographic Services (ADS). We thank John Stauffer for kindly providing the optical spectra of the K and M Hyades members published in 1997 (Stauffer et al. 1997a)

Converging Underwater and FSO Ground Communication Links

We propose a new combined underwater-atmospheric optical communication link for providing a high speed optical connectivity between onshore and sumerge systems. New average BER expressions are derived when assuming amplify-and-forward (AF) relay.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

How did the Sovereign debt crisis affect the Euro financial integration? A fractional cointegration approach.

This paper examines financial integration among stock markets in the Eurozone using the prices from each stock index. Monthly time series are constructed for four major stock indices for the period between 1998 and 2016. A fractional cointegrated vector autoregressive model is estimated at an international level. Our results show that there is a perfect and complete Euro financial integration. Considering the possible existence of structural breaks, this paper also examines the fractional cointegration within each regime, showing that Euro financial integration is very robust. However, in the financial and sovereign debt crisis regime, IBEX 35 appears to be the weak link in Euro financial integration, unless Euro financial integration recovers when this period ends

Scalable video transcoding for mobile communications

Mobile multimedia contents have been introduced in the market and their demand is growing every day due to the increasing number of mobile devices and the possibility to watch them at any moment in any place. These multimedia contents are delivered over different networks that are visualized in mobile terminals with heterogeneous characteristics. To ensure a continuous high quality it is desirable that this multimedia content can be adapted on-the-fly to the transmission constraints and the characteristics of the mobile devices. In general, video contents are compressed to save storage capacity and to reduce the bandwidth required for its transmission. Therefore, if these compressed video streams were compressed using scalable video coding schemes, they would be able to adapt to those heterogeneous networks and a wide range of terminals. Since the majority of the multimedia contents are compressed using H.264/AVC, they cannot benefit from that scalability. This paper proposes a technique to convert an H.264/AVC bitstream without scalability to a scalable bitstream with temporal scalability as part of a scalable video transcoder for mobile communications. The results show that when our technique is applied, the complexity is reduced by 98 % while maintaining coding efficiency