Similarity networks for classification: a case study in the Horse Colic problem

This paper develops a two-layer neural network in which the neuron model computes a user-defined similarity function between inputs and weights. The neuron transfer function is formed by composition of an adapted logistic function with the mean of the partial input-weight similarities. The resulting neuron model is capable of dealing directly with variables of potentially different nature (continuous, fuzzy, ordinal, categorical). There is also provision for missing values. The network is trained using a two-stage procedure very similar to that used to train a radial basis function (RBF) neural network. The network is compared to two types of RBF networks in a non-trivial dataset: the Horse Colic problem, taken as a case study and analyzed in detail.Postprint (published version

Broadband transverse susceptibility in multiferroic Y-type hexaferrite Ba0.5Sr1.5Zn2Fe12O22

Producción CientíficaNoncollinear spin systems with magnetically induced ferroelectricity from changes in spiral magnetic ordering have attracted significant interest in recent research due to their remarkable magnetoelectric effects with promising applications. Single phase multiferroics are of great interest for these new multifunctional devices, being Y-type hexaferrites good candidates, and among them the ZnY compounds due to their ordered magnetic behaviour over room temperature. Polycrystalline Y type hexaferrites with composition Ba0.5Sr1.5Zn2Fe2O22 (BSZFO) were sintered in 1050 °C–1250 °C temperature range. Transverse susceptibility measurements carried out on these BSZFO samples in the temperature range 80–350 K with DC fields up to ± 5000 Oe reveal different behaviour depending on the sintering temperature. Sample sintered at 1250 °C is qualitatively different, suggesting a mixed Y and Z phase like CoY hexaferrites. Sintering at lower temperatures produce single phase Y-type, but the transverse susceptibility behaviour of the sample sintered at 1150 °C is shifted at temperatures 15 K higher. Regarding the DC field sweeps the observed behaviour is a peak that shifts to lower values with increasing temperature, and the samples corresponding to single Y phase exhibit several maxima and minima in the 250 K–330 K range at low DC applied field as a result of the magnetic field induced spin transitions in this compound.Ministerio de Ciencia, Innovación y Universidades; Agencia Estatal de Investigación with FEDER (MAT2016-80784-P

The Role of Social Networks on Regulation in the Telecommunication Industry

This paper studies the welfare implications of equilibrium behavior in a market characterized by competition between two interconnected telecommunication firms, subject to constraints: the customers belong to a social network. It also shows that social networks matter because equilibrium prices and welfare critically depend on how people are socially related. Next, the model is used to study effectiveness of alternative regulatory schemes. The standard regulated environement, in which the authority defines interconnection ac cess charges as being equal to marginal costs and final prices are left to the market, is considered as a benchmark. Then, we focus on the performance of two different regulatory interventions. First, access prices are set below marginal costs to foster competition. Second, switching costs are reduced to intensify competition. The results show that the second strategy is more efective to obtain equilibrium prices closer to Ramsey's level.Access charges, social networks, random regular graphs

Synthesis, structural characterization and broadband ferromagnetic resonance in Li ferrite nanoparticles

Producción CientíficaLithium ferrites are well known materials due to its numerous technological applications especially in microwave devices. Lithium ferrite nanoparticles were prepared by sol-gel technique by means of Pechini method, and then annealed at different temperatures in 250–1000 °C range. XRD confirms spinel formation with particles sizes in 15–700 nm range, with increased size with annealing temperature, whereas FTIR and Raman measurement confirm that single phase lithium ferrite with ordered cationic structure is obtained. Microwave magnetoabsorption data of the annealed lithium ferrite nanoparticles were obtained with a broadband system based on a network analyzer that operates up to 8.5 GHz. At fields up to 200 mT we can observe a broad absorption peak that shifts to higher frequencies with magnetic field according to ferromagnetic resonance theory. The amplitude of absorption, up to 85%, together with the frequency width of about 5.5 GHz makes this material suitable as wave absorber. FMR parameters like resonance field, linewidth and broadening are analyzed in order to obtain the characteristic parameters and analyze the microwave behaviour.Ministerio de Economía, Industria y Competitividad ( project MAT2016-80784-P

Influence of the Compaction Pressure and Sintering Temperature on the Mechanical Properties of Porous Titanium for Biomedical Applications

In the present work, the use of porous titanium is proposed as a solution to the difference in stiffness between the implant and bone tissue, avoiding the bone resorption. Conventional powder metallurgical technique is an industrially established route for fabrication of this type of material. The results are discussed in terms of the influence of compaction pressure and sintering temperature on the porosity (volumetric fraction, size, and morphology) and the quality of the sintering necks. A very good agreement between the predicted values obtained using a simple 2D finite element model, the experimental uniaxial compression behavior, and the analytical model proposed by Nielsen, has been found for both the Young’s modulus and the yield strength. The porous samples obtained by the loose sintering technique and using temperatures between 1000 °C −1100 °C (about 40% of total porosity) are recommended for achieving a suitable biomechanical behavior for cortical bone partial replacement.Ministry of Economy and Competitiveness of the State General Administration of Spain grant MAT2015-71284-

Quadratic Maps in Two Variables on Arbitrary Fields

Let $\mathbb{F}$ be a field of characteristic different from $2$ and $3$, and let $V$ be a vector space of dimension $2$ over $\mathbb{F}$. The generic classification of homogeneous quadratic maps $f\colon V\to V$ under the action of the linear group of $V$, is given and efficient computational criteria to recognize equivalence are provided.Comment: 12 pages, no figure

Aspectos técnico-económicos de los vertidos de aguas residuales y depuraciones

La primera consiste en un análisis del, problema de la escasez del agua, analizando sus causas naturales y la influencia del hombre sobre estos recursos. La segunda parte consiste en un análisis e investigación sobre los elementos con los que el hombre cuenta para influir sobre los condicionantes que limitan los recursos hidráulicos disponibles, principalmente los relacionados con la contaminación» tratamiento de las aguas y reutilzación. La tercera parte es un estudio económico de todas las soluciones, marcando la bondad desde el punto de rentabilidad de cada una de las soluciones frente a las otras, proponiendo por fin el caminó a seguir en España dada la situación actual y su evolución hacia el futuro

Comunicación y conflicto familiar en Las Traquinias

La autora se centra principalmente en el análisis de la comunicación en Las Traquinias de Sófocles. Se analiza la aceptación o el rechazo de los vínculos afectivos a través del uso de los términos familiares. También se estudian las muertes de Deyanira y Heracles, así como el papel de Hilo como herramienta de comunicación entre sus padres.The author focuses mainly on the analysis of communication in Sophocles's Trachiniae. The acceptance or repudiation of the affective bonds by the main characters is analyzed by means of the use of family terms. Deianira's and Heracles's deaths are also studied, as well as the role of Hyllus as a communicational tool between his parents

Demosthenes, "Fourth Philippic": new critical edition

Presentamos una nueva edición crítica del la Cuarta Filípica de Demóstenes, en la que por primera vez incorporamos sistemáticamente el testimonio de un buen número de manuscritos recentiores, especialmente hispánicos, además del de las ediciones aldinas.We present a new critical edition of Demosthenes’ Fourth Philippic. For the first time, we incorporate systematically the evidence of a signifi cant number of recentiores, especially Hispanici, besides the Aldine editions