Coloquio de La Habana: "Encuentro sobre la deuda externa de América Latina y el Caribe". Argentina

El problema de la deuda externa viene ocupando, en estos últimos años, un lugar central en el escenario económico y político de América Latina. El dramatismo de la situación ha sido subrayado repetidamente, y los indicadores que reflejan el comportamiento negativo del producto, la ocupación, la inversión, las presiones inflacionarias, los salarios reales, el drenaje de reservas internacionales y todas las demás magnitudes macroeconómicas relevantes, dan testimonio fehaciente de la gravedad de la crisis, en la que el peso abrumador de la deuda es el principal elemento determinante

La financiación de los partidos políticos: un enfoque de elección pública

Aunque es admitida la importancia que tiene la financiación legal de los partidos políticos para el buen funcionamiento de la democracia representativa, es una práctica frecuente recurrir a la financiación irregular. En las dos últimas décadas se han detectado numerosos casos de financiación ilegal en todo el mundo. Aunque la magnitud de las tramas ilegales difiere de unos países a otros, su conocimiento por el público ha propiciado que la mayoría de los países emprendieran reformas en las leyes que regulan la financiación de los partidos. La primera sección de este artículo describe los rasgos más destacados que tiene la financiación legal de los partidos en un buen número de países con democracias consolidadas. En las secciones segunda y tercera se exponen por separado los argumentos en favor de la financiación pública y privada. En las conclusiones sugerimos que los partidos pueden utilizar la reforma de las leyes de financiación para reconquistar la confianza de los votante

Structural analysis and sintering aids effects in La2Ce2O7 proton conductors

Global warming is an important problem that has to be solved without delay. The development of environmental-friendly energy technology is needed to deal with this issue. Solid Oxide Fuel Cells (SOFC) technology has been proposed as a real alternative to fossil fuel combustion. Proton conductors like La2Ce2O7 (LDC), has several advantages in comparison with BaCeO3 due to its high stability in H2O or CO2 conditions [1]. Furthermore, for industry application is necessary to low the high sintering temperature of typical electrolyte materials. La2Ce2O7 was synthesized by the freeze-drying precursor method and calcination conditions have been optimized to obtain single phase with high compaction at 1400 ºC for 1h. A fully characterization has been carried out using X-ray powder diffraction and scanning electron microscopy. The total conductivity was determined by complex impedance spectroscopy in dry and wet air. Transmission Electron Microscopy (TEM) was used to clarify certainly the structure of La2Ce2O7 due to its still unknown. SAEDs patterns revealed a disordered fluorite, not appearing secondary reflections typical of pyrochlore superstructure, finishing the controversy around the correct structure in this material [2,3]. Moreover, an exhaustive study about lowering the sintering temperature with Co and Zn as sintering aids has been investigated obtaining electrolytes that can be used for SOFC. The sintering aids were impregnated using cobalt and zinc nitrates in ethanol media. Both sintering aids allow for obtain high dense pellets lowering the sintering temperature 300 ºC and 400 ºC for samples with cobalt and zinc, respectively, without compromising the electrical and microstructural properties (Fig 1).Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tec

Partial cooperation and convex sets

We consider games of transferable utility, those that deal with partial cooperation situations, made up of coalition systems, in which every unit coalition is feasible and every coalition of players can be expressed as a disjoint union of maximal feasible coalitions. These systems are named partition systems and cause restricted games. To sum up, we study feasible coalition systems defined by a partial order designed for a set of players and we analyze the characteristics of a feasible coalition system developed from a family of convex sets

Influence of lanthanum doping on the structure and transport properties of CeO2

LaxCe1-xO2-x/2 materials are oxide and/or proton conductors depending on the La-content and they are of interest for numerous electrochemical applications at high temperatures, including membranes for hydrogen separation and fuel cell electrolytes. Samples with low La-content exhibit (x0.4) crystallize with cubic fluorite type structure; while for x>0.4 the structure is still unclear. The crystal structure of these materials is still unknown, some authors reported that the materials exhibit fluorite type structure in the whole compositional range. However, another authors reported a pyrochlore type structure for x0.5. The stabilization of the fluorite or pyrochlore type structure depends mainly on the oxygen sublattice and the vacancy ordering1. In this contribution, LaxCe1-xO2-δ (0<x0.7) materials are prepared by the freeze-drying precursor method and the sintering conditions have been optimized to obtain dense ceramic samples. A complete structural characterization has been carried out by X-ray powder diffraction and scanning electron microscopy. The average structure determined by conventional XRD indicates that the materials are single fluorite compounds for x0.6. However, the local structure determined by combined electron diffraction and HRTEM is more complex. The SAED patterns reveal diffuse scatterings for x0.5 that have been associated with O-vacancy ordering, leading to a superstructure relative to a single fluorite . This finding is further confirmed by the HRTEM images in the same zone axis. Thermogravimetric and Raman analysis confirmed an increase of oxygen vacancy concentration with La-doping. The overall conductivity was determined by complex impedance spectroscopy in different atmospheres. The samples with high La-content exhibit an important proton contribution at low temperature. In addition, all samples are mixed ion-electronic conductors in hydrogen containing atmosphereUniversidad de Málaga. Campus de Excelencia Internacional Andalucía Tec

Heterogeneous data source integration for smart grid ecosystems based on metadata mining

The arrival of new technologies related to smart grids and the resulting ecosystem of applications andmanagement systems pose many new problems. The databases of the traditional grid and the variousinitiatives related to new technologies have given rise to many different management systems with several formats and different architectures. A heterogeneous data source integration system is necessary toupdate these systems for the new smart grid reality. Additionally, it is necessary to take advantage of theinformation smart grids provide. In this paper, the authors propose a heterogeneous data source integration based on IEC standards and metadata mining. Additionally, an automatic data mining framework isapplied to model the integrated information.Ministerio de Economía y Competitividad TEC2013-40767-

Study and Design of a Diferentially Fed Tapered Slot Antenna Array

The results of a parametric study and design of an ultrawideband dual-polarized array of differentially-fed tapered slot antenna elements are presented. We examine arrays of bunny-ear antennas and discuss the capabilities and limitations of differential antenna technology. As we focus on radio astronomical applications, the absence of a balancing-feed circuit not only reduces the first-stage noise contribution associated to losses in the feed, but also leads to a cost reduction. Common-modes are supported by the antenna structure when a third conductor is present, such as a ground plane. We demonstrate that anomalies may occur in the differential-mode scan impedance. Knowledge of both types of scan impedances, differential and common mode, is required to properly design differential LNAs and to achieve optimal receiver sensitivity. A compromise solution is proposed based on the partial suppression of the undesired common-mode currents through a (low loss) balancing-dissipation technique. A fully steerable design up to 45?? in both principal planes is achieved

Forecasting Recharging Demand to Integrate Electric Vehicle Fleets in Smart Grids

Electric vehicle fleets and smart grids are two growing technologies. These technologies provided new possibilities to reduce pollution and increase energy efficiency. In this sense, electric vehicles are used as mobile loads in the power grid. A distributed charging prioritization methodology is proposed in this paper. The solution is based on the concept of virtual power plants and the usage of evolutionary computation algorithms. Additionally, the comparison of several evolutionary algorithms, genetic algorithm, genetic algorithm with evolution control, particle swarm optimization, and hybrid solution are shown in order to evaluate the proposed architecture. The proposed solution is presented to prevent the overload of the power grid

Projectile motion revisited: Does the distance between the launcher and the object always increase?

In this paper, we have shown that parabolic motion from a critical launch angle has an unexpected property related to the distance between the object and the launcher. This distance decreases in a time interval that occurs between two moments: one, in which distance has a maximum and another in which it has a minimum. As it will be shown, this only happens in launch angles greater than cos∅c = 1/3, that is ∅c ≅ 70.53º. The launch we have studied occurs from the ground and we have not taken into account air friction. We have not considered the possible variations in the acceleration of gravity, that is, we have taken it as a constant throughout the movement of the projectile. We have used dimensionless coordinates so that the focus is on the angular variable. In addition, at the end of the study, we have used polar variables to visualize what happened. This is a very didactic approach, which can be used in the first year of STEM university degrees. It will also prove useful for teachers that wish to explain parabolic motion in their classes.AB is grateful to Universidad de Alicante (Spain) for help provided throughout the project GITE-09006-UA. IE is grateful to Ministry of Economy and Competitiveness for the help provided throughout the project RTI2018-099041-B-I00

Confección de claves de identificación para los parques urbanos de Melilla. Un recurso didáctico

En el marco de un proyecto de innovación docente, desarrollado en la Facultad de Educación de Melilla, se están confeccionando materiales didácticos para el ciclo superior de Educación Primaria, entre ellos claves botánicas cientifico-didácticas para los parques de la ciudad de Melilla. En este trabajo se describe el proceso de diseño y elaboración, así como su implementación en varios colegios, tanto en salidas de campo como en la versión virtual, poniéndose de manifiesto el alto valor didáctico de estos documentos que favorecen el acercamiento del niño al trabajo del científico. La botánica, en este caso, se convierte en un recurso valioso para abordar objetivos y competencias preconizados en la legislación para diferentes áreas, especialmente Conocimiento del Medio y las instrumentales de Lengua y Matemáticas