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This article seeks to explain the contradiction between the promises of welfare gains derived from the economic models recommending the removal of immigration restrictions and the realities experienced by countries attempting to apply restrictions to immigration flows. A formal model is built in which the strategic reaction of countries considers not only the benefits derived from migration but also the (economic and non-economic) costs that migration can generate in the host country. Strategic reactions drive what may be called the “paradox of adverse interest”: the fewer potential gains associated with liberalization of migration, the easier it becomes for nations to reach an unrestrictive agreement. The existence of two asymmetries (between the bargaining power of receiving and sending countries, and between the private nature of most of migration’s benefits and the social nature of its main costs) can hinder the agreement when the countries involved exhibit a high wage differential. Results suggest that permissive international agreements on migration are easier to reach in regional contexts, among countries with proximate economic conditions and levels of income.

The Baconao Lagoon is a tropical, coastal and littoral ecosystem which receives continuous natural and human perturbations; favoring the eutrophication process, and consequently, the phytoplankton proliferation. The starting point of this research begins with a massive fish kill report into the lagoon on May 2017, being the main objective to document the implementation of a risk management protocol for the phycotoxin presence, adapted to the ecosystem conditions, considering the characterization of the risk event, focusing on mitigation and prevention of negative impacts. The presence of a mix Harmful Algal Bloom (HAB) in remission was confirmed, with negative implications to the entire ecosystem. It was identified the presence of abundant motile cells of Gymnodinium sp., Karlodinium micrum and dinoflagellate cells rests, as well as high values of chlorophyll a, being the highest concentration 20.37 ± 0.04 µgL-1; low values of dissolved oxygen, and an important bacterial contamination, with the dominance of cyanobacteria. The implementation of a risk management protocol was documented with important methodological guidelines to follow to the management of similar risk events, where the intersectoral alliance performs a key success factor. RESUMEN La laguna de Baconao es una laguna tropical costero-litoral, con constantes perturbaciones antrópicas y naturales; escenario que favorece la eutrofización, con tendencia a la proliferación del fitoplancton. El desarrollo de esta investigación comienza con un registro de muerte masiva de peces en la laguna, en mayo de 2017, siendo el objetivo principal documentar la implementación de un protocolo de gestión del riesgo por contaminación con ficotoxinas, adaptado a las condiciones del ecosistema, a partir de la caracterización de la situación de riesgo, enfocado a la mitigación y prevención de impactos negativos. Se confirma la existencia de una Floración Algal Nociva (FAN) mixta en remisión, con implicaciones negativas en todo el ecosistema, así como la presencia de células vivas de Gymnodinium sp., Karlodinium micrum, y abundantes restos de células de otros dinoflagelados; altos valores de clorofila a, con una concentración máxima de 20,37 ± 0,04 µgL-1; bajos valores de oxígeno disuelto y elevada contaminación bacteriana, con predominio de cianobacterias. Se documenta la implementación de un protocolo de gestión del riesgo con importantes pautas metodológicas a seguir para el manejo de similares eventos de riesgo, donde la alianza intersectorial constituyó un factor clave de éxito.

We report the temperature dependent THz to mid-infrared response of hexagonal-ErMnO3 using absorption, reflectivity, and emissivity techniques from 2 K to 1700 K. At low temperatures, lowest frequency vibrational modes coexist with paramagnon excitations associated with well-defined crystal field Rare Earth pure magnetic replicas in an intriguing phonon-magnetic convergence. Increasing the temperature, a number of vibrational bands close to the space group predicted undergo profile broadening and softening. In particular, a distinctive set of bands in the 288-329 cm-1 (300 K) range has a component whose profile is carrier screened becoming nearly fully blurred in the intermediate phase between ~830 K and ~1500 K. Below TC ~830 K this asymmetric band further splits as spin phonon interaction and the tripling of the unit cell takes place revealing a delicate balance of long- and short-range interactions. Ambient Raman scattering brings up evidence of a Fr\"ohlich resonance due to Coulomb interactions between carriers and the macroscopic field of the longitudinal optical phonon mode. We found it is dynamically correlated to the hexagonal c-axis negative thermal expansion. Mid-infrared (MIR) optical conductivity show that also plays a role in small polarons and mediates in high temperature bipolarones.At higher temperatures a low frequency Drude contribution is triggered by electron hopping signaling an insulator-metal phase transition at ~1600 K while the MIR response suggests coexistence between single small polarons and bipolarons. We draw a parallel with improper ferroelectrics sustaining a lattice incommensurate intermediate phase and unit cell tripling. We argue that in the h-RMnO3 (R=Rare Earth, Y) family of compounds the intermediate phase be considered incommensurate with onset at TINC ~1500 K and ferroelectric lock-in at TC ~830 K delimiting this regime in h-ErMnO3., Comment: Manuscript and Supplemental Material (66 pages)

We report the temperature dependent THz to mid-infrared response of hexagonal-ErMnO3 using absorption, reflectivity, and emissivity techniques from 2 K to 1700 K. At low temperatures, lowest frequency vibrational modes which extend up the lock-in ferroelectric temperature, coexist with paramagnon excitations and are associated with well-defined crystal field Rare Earth pure magnetic replicas in an intriguing phonon-magnetic convergence enhancing the multiferroic character of h-ErMnO3. Increasing the temperature, a number of vibrational bands close to the space group predicted undergo profile broadening and softening. In particular, a distinctive set of bands in the 288-329 cm-1 (300 K) range has a component whose profile is carrier screened becoming nearly fully blurred in the intermediate phase between ~830 K and ~1500 K. Below TC ~830 K this asymmetric band, having one component still partially screened, further splits as spin phonon interaction and the tripling of the unit cell takes place revealing at TN ~79 K a delicate balance of long- and short-range interactions. Ambient Raman scattering brings up evidence of a Fröhlich resonance due to Coulomb interactions between carriers and the macroscopic field linked to the corresponding longitudinal optical phonon mode. We found it is dynamically correlated to the hexagonal c-axis negative thermal expansion. Quantitative analyses of the mid-infrared (MIR) optical conductivity show that also plays a role in small polarons and mediates in high temperature bipolarones. Bipolaron profiles at high temperatures change as the sample opacity increases when at ~900 K straight stripes turn curly toward complex vortex-antivortex domain patterns in the paraelectric phase. At still higher temperatures a low frequency Drude contribution is triggered by electron hopping signaling an insulator-metal phase transition at ~1600 K while the MIR response suggests coexistence between single small polarons and bipolarons. On closing, we draw a parallel with improper ferroelectrics sustaining a lattice incommensurate intermediate phase and unit cell tripling. We argue that in the h-ErMnO3 (R=Rare Earth, Y) family of compounds the intermediate phase be considered incommensurate with onset at TINC ~1500 K and ferroelectric lock-in at TC ~830 K delimiting this regime in h-ErMnO3., Centro de Química Inorgánica

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RESUMEN Esta investigación presenta un nuevo método de síntesis de un solo paso para obtener Cr2O3 nanoestructurado a partir de una solución de nitrato de cromo y un combustible como ácido aspártico, o lisina, o trihidroximetilaminometano, o etilendiaminotetraacético. Una vez obtenido los polvos fueron calcinados a 500ºC. Luego se caracterizaron mediante difracción de rayos X (DRX), microscopía electrónica de barrido (MEB), microscopía electrónica de transmisión (TEM), espectroscopía infrarroja por transformada de Fourier (FTIR), espectroscopía por UV-Visible y técnicas de Brunauer–Emmett–Teller (BET). Estos polvos serán utilizados en superficies absorbedoras como cermts o pinturas selectivas solares. En las cenizas y los polvos calcinados obtenidos se identificó la estructura cristalina del Cr2O3, correspondiente al sistema romboédrico y al grupo espacial R-3c. El tamaño promedio de cristalita de los productos obtenidos estuvo entre 29 y 45 nm, donde para las cenizas el tamaño fue menor en comparación a los polvos obtenidos para todos los combustibles utilizados. Es probable que para un incremento de la temperatura el tamaño de cristalita crezca. Un área específica de 167 m2/g fue determinada para las cenizas obtenidas con ácido aspártico. Este fue el mayor valor observado en la literatura específica y podría utilizarse para reacciones de catálisis, mientras que el resto de los valores obtenidos para las cenizas fue mayor en comparación a los polvos calcinados para todos los combustibles. El tamaño promedio de partícula observado a través de TEM resultó entre 50 y 100 nm aproximadamente. La energía de Band Gap determinada resultó entre 3.055 eV y 3.078 eV, esta variable aumenta suavemente con la temperatura de calcinación. Para confirmar esta tendencia se deberían realizar mayor cantidad de experimentos. ABSTRACT This research presents a novel one–step solution combustion synthesis to obtain nano-structured Cr2O3 from chrome nitrate solution and one fuel such as aspartic acid (Asp) or Lysine (Lys), or Autor Restrihydroxymethylaminomethane (Tris) or ethylenediaminetetraacetic acid (Edta). Once obtained, the ashes were calcined at 500°C. The powders were characterized by x-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), infrared spectroscopy with Fourier transform (FTIR), UV-Visible Spectroscopy (UV-VIS) spectroscopy and Brunauer–Emmett–Teller (BET) techniques. These powders will be used in solar absorbing surfaces: in composites (o cermets) and painted coatings. Within the obtained ashes and calcined powders, it was identified a Cr2O3 crystalline structure corresponding to the rhombohedral system and to the R-3c spatial group. The average crystallite size was determined for ashes and calcined powders, this value was in nanometric range between 29 and 45 nm, where for ashes were in general minor than calcined powders in all cases. It is probable that with an increment of the temperature, crystallite size would grow. A specific area of 167 m2/g was determined for asp-ashes. This was a highest value observed in specific literature and it could be used in catalysis reactions, while the area values of ashes was higher than calcined powders value for each fuel. The average particle size observed through TEM resulted in 50 nm to 100 nm approximately. The determined Energy band gap resulted in 3.055eV to 3.078 eV approximately. The Energy band gap slightly increased with calcination temperature. Further trials and investigation will confirm the mentioned tendencies.

OBJECTIVES: The REAC-TAVI (Assessment of platelet REACtivity after Transcatheter Aortic Valve Implantation) trial enrolled patients with aortic stenosis (AS) undergoing transcatheter aortic valve replacement (TAVR) pre-treated with aspirin + clopidogrel, aimed to compare the efficacy of clopidogrel and ticagrelor in suppressing high platelet reactivity (HPR) after TAVI. BACKGROUND: Current recommendations support short-term use of aspirin + clopidogrel for patients with severe AS undergoing TAVR despite the lack of compelling evidence. METHODS: This was a prospective, randomized, multicenter investigation. Platelet reactivity was measured at 6 different time points with the VerifyNow assay (Accriva Diagnostics, San Diego, California). HPR was defined as (P2Y12 reaction units (PRU) ≥208. Patients with HPR before TAVR were randomized to either aspirin + ticagrelor or aspirin + clopidogrel for 3 months. Patients without HPR continued with aspirin + clopidogrel (registry cohort). The primary endpoint was non-HPR status (PRU

El presente trabajo de investigación tiene la finalidad de crear conocimiento en un campo tan de actualidad como es el del terrorismo, existiendo cuestiones de peso como la necesidad de conocer la evolución del terrorismo en un futuro a corto y medio plazo. La hipótesis de partida es que el concepto de terrorismo si bien no sufrirá cambios conceptuales, sí que observará cambios en sus formas, siendo las redes sociales un elemento clave en la configuración del futuro terrorismo, es por eso que se parte de la hipótesis de que en un futuro a corto plazo se iniciará la quinta oleada terrorista caracterizada por el incremento de actos terroristas cometidos por actores individuales, ya sean lobos solitarios o terroristas individuales. El presente trabajo se ha basado en el análisis documental de la literatura disponible en el campo del análisis terrorista, acudiendo a fuentes de primera mano creadas por diferentes universidades y autores sobretodo de origen europeo y norteamericano. La hipotesis planteada ha sido confirmada por los datos aportados por la diferente literatura consultada, dando lugar a unas conclusiones que se espera puedan ser de utilidad para otros investigadores.

We report on the high-temperature evolution of far- and mid-infrared reflectivity and emissivity spectra of ambient orthorhombic ErMnO3 from 12 K to sample decomposition above 1800 K. At low temperatures the number of phonons agrees with the predictions for orthorhombic space group D2h16-Pbnm (Z=4) and coexists with a paramagnon spin resonance and rare-earth crystal-field transitions. Increasing the temperature, a number of vibrational bands undergo profile broadening and softening approaching the orbital disordered phase where the orthorhombic Ó lower-temperature cooperative phase coexists with cubic-orthorhombic O. O-ErMnO3 undergoes a first-order order-disorder transition into the perovskite cubic phase at Tcubic∼1329K±20K where the three triple degenerate phonons allowed by the space group Pm-3m (Z=1) are identified. At about 800 K, a quantitative small polaron analysis of the orthorhombic midinfrared real part optical conductivity shows that antisymmetric and symmetric breathing modes sustain the strongest electron-phonon interactions. Above Tcubic the bipolaron fingerprint profile is the midinfrared dominant and only feature. Its appearance correlates with the localized screening of the highest vibrational mode reststrahlen band. We propose that the longitudinal optical mode macroscopic field screening is a consequence of dynamically sharing δ disproportioned eg electrons hovering over the Jahn-Teller distorted octahedral dimer {Mn(QJT)3+δ[Mn(QJT)[3]-δ]O6/2}2. A thermal driven insulator-metal transition is detected with onset ∼1600 K. We also address the occurrence of an inhomogeneity induced terahertz band result of heating the samples in dry air, triggering Mn3+-Mn4+ double exchange, under the presence of Mn4+ smaller ions stabilizing the orthorhombic lattice., Centro de Química Inorgánica

El presente trabajo está enfocado a facilitar la realización de prácticas con equipamiento de laboratorio físico en remoto, gestionando el acceso a los diferentes equipos de forma exclusiva para un alumno o grupo de alumnos. Este trabajo pretende contribuir a la realización de prácticas por parte de los alumnos, ofreciéndoles la posibilidad de realizar prácticas con equipamiento real, pero eliminando las dificultades inherentes al acceso físico a dicho laboratorio. La Escuela dispone de dos kits de laboratorios oficiales Cisco para los cursos CCNA Routing & Switching o CCNA Security que se utilizan en diferentes asignaturas de grado y máster. Debido al tipo de laboratorio, las prácticas sólo podían ser presenciales. Sin embargo, recientemente se incorporó un multiplexador de conexiones de consola a los dispositivos de los kits (routers y switches) que posibilita su acceso remoto mediante Secure Shell (SSH). Además, se diseñó un sistema que permite, con una única configuración física (conexionado completo), acceder a diferentes escenarios virtuales (topología lógica) tan sólo deshabilitando conexiones. De esta forma, los alumnos pueden realizar prácticas de laboratorio desde su casa, y los laboratorios se pueden utilizar durante un horario mucho mayor. Actualmente existe una aplicación que permite la reserva de turnos por parte de los alumnos y a la vez permite la gestión de las prácticas por parte de los profesores. Dicho sistema permite que los profesores creen prácticas, incluyendo un enunciado y una configuración inicial. Los alumnos, por su parte, puedan reservar turno en uno de los dos kits disponibles y, llegado el momento, proceder a iniciar la práctica. Una vez la práctica es iniciada, el servidor que alberga la aplicación ejecuta un comando para llevar a cabo el control de acceso. En esta versión dicho control de acceso es muy limitado, basado en el establecimiento de reglas de firewall que se detallarán más adelante. Este proyecto consiste en el reemplazo de esta aplicación con otra nueva que, ofreciendo la misma funcionalidad, provee una interfaz más actual y amigable, mejora algunos aspectos de la funcionalidad de la misma, añade funcionalidades de gestión para el administrador del sistema de manera que no tenga que hacer cambios directamente en la base de datos y, por encima de todo, cambia la manera en la que los alumnos realizan las prácticas, sin tener que habilitar y deshabilitar IPs. Para lograr este último objetivo, la nueva aplicación ofrece al alumno acceder a los kits mediante una consola web que ofrece exactamente la misma experiencia que si se conectase directamente vía SSH. El alumno, sin embargo, estará en realidad interactuando con el servidor de esta aplicación y no directamente con los kits. Por detrás, es el servidor el que tiene acceso a los kits y gestiona las conexiones SSH con los mismos. De esta manera, es el propio servidor el que determina cuando un alumno tiene permitido el acceso, que será sólo cuando éste haya hecho la reserva correspondiente.

Se plantea que el alumnado construya una maceta que mediante la programación de una placa Arduino proceda al riego de una planta cuando la tierra no disponga de la humedad suficiente. Con este proyecto se logra aglutinar varios criterios de evaluación, desde el estudio de la instalación eléctrica en la vivienda, hasta el control de la placa Arduino, pasando por el conocimiento de los diferentes sensores y sistemas de comunicación. ESP

Hoy en día, son muchas las personas que pierden la vida debido a los accidentes de tráfico. Por ello, los ingenieros de la industria automovilística buscan desarrollar nuevas tecnologías y aplicaciones que permitan reducir el número de víctimas, hasta llegar al caso ideal de que dicho número sea nulo. Éste proyecto busca proteger a los peatones en vías urbanas e interurbanas. El objetivo es diseñar un algoritmo que, mediante la fusión de un escáner láser y una cámara en el interior del vehículo, sea capaz de detectar de manera rápida y precisa peatones en tiempo real. Además, deberá de indicar sus coordenadas al conductor, para que éste sepa dónde se encuentran dichos peatones. Para desarrollar dicho algoritmo, se utilizan los algoritmos HOG (histograma de gradientes orientados) y SVM (máquina de soporte vectorial). El HOG es un método que se basa en la orientación del gradiente en áreas locales de una imagen para encontrar los objetos de dicha imagen. Destaca por su robustez ante los cambios de iluminación, en los fondos y en los objetos. El SVM por su parte, es un clasificador, el cual se usará para realizar el entrenamiento del HOG. Para mejorar el rendimiento, se hará un estudio de los parámetros del sistema que permiten conseguir los mejores resultados, tanto en el tiempo computacional como en la eficiencia en la detección. Por último, se recurrirá también a las librerías de OpenCV, útiles para el procesamiento de imágenes. Nowadays, so many people lose their lives due to traffic accidents. For that reason, the automobile industry engineers try to develop new technologies and applications that let reduce the number of victims, until get the ideal situation which this number is zero. This project tries to protect pedestrians in urban and intercity roads. The aim is design an algorithm that, through a fusion of a Scanner laser and a camera inside the vehicle, can be able to detect pedestrians quickly and accurately in real time. Also, it has to show the coordinates to the driver, in order to know the location of these pedestrians. To develop this algorithm, HOG (Histogram of Orientated Gradients) and SVM (Support Vector Machine) algorithms are used. The HOG method is based on the gradient orientation in local portions of an image and is used to detect the objects of that image. It offers good results due its invariance in illumination changes, backgrounds and objects. The SVM, meanwhile, is a classifier. It will be used to train the HOG. To improve the performance, a study of the system parameters is performed in order to get the best results in computational time as well as in detection efficiency. Finally, OpenCV libraries will be used because their utility in image processing. Ingeniería Electrónica Industrial y Automática

RESUMEN El calendario de vacunación en España es una herramienta dinámica de salud pública que ha ido incorporando cambios en función de la situación epidemiológica y la evidencia científica. La Ponencia del Programa y Registro de Vacunaciones, órgano científico-técnico del Consejo Interterritorial del Sistema Nacional de Salud, realiza evaluaciones y propone modificaciones que se incorporan en el calendario de vacunación de las comunidades autónomas (CCAA). Este artículo está dividido en dos partes y presenta la evaluación realizada para proponer un nuevo esquema de vacunación frente a difteria, tétanos, tosferina, poliomielitis, hepatitis B y enfermedad invasora por Haemophilus influenzae tipo b, centrándose esta primera parte en la exposición de motivos, el repaso a la política de vacunación en España y su impacto así como en la revisión de los calendarios de vacunación en países de nuestro entorno. ABSTRACT The immunization schedule is a dynamic public health tool that has incorporated different changes over the years influenced by the epidemiologic situation and the scientific evidence. The Immunization Advisory Committee [Ponencia de Programa y Registro de Vacunaciones], as the Interterritorial Council scientific and technical advisory body, carries out assessments of different programmes and vaccines and proposes changes that after approval will be introduced in the Regions schedule. This article is divided into two parts presenting the rationale followed to propose a new schedule for the immunization against diphtheria, tetanus, pertussis, hepatitis B and invasive disease by Haemophilus influenzae type b. This first part is focused in the reasoning to undertake the assessment, the review of the immunization policy and the impact of immunization in Spain, as well as a review of the immunization schedules in similar countries.

RESUMEN En este documento se justifican los fundamentos inmunológicos y clínicos para abordar una modificación del Calendario de Vacunación Infantil de España para el año 2016. Se revisa la inmunogenicidad y la experiencia clínica con esquemas de vacunación de dos dosis como primovacunación en el primer año de vida y una dosis de recuerdo precoz, para los antígenos de difteria, tétanos, tosferina, Haemophilus influenzae tipo b, poliomielitis y hepatitis B. Por sus peculiaridades también se considera el impacto clínico que esta pauta de vacunación podría tener en el lactante prematuro. Debido a que varias comunidades autónomas administran la primera dosis de vacuna de hepatitis B al nacimiento, se exponen las condiciones que se deberían cumplir para iniciar la vacunación a los dos meses de vida. Se emiten las recomendaciones de calendario que incluyen como principales cambios la administración de las vacunas hexavalentes a los 2, 4 y 11 meses, añadiendo la recomendación del uso de vacuna DTPa-VPI a los seis años de edad. ABSTRACT Immunization schedules are intrinsically dynamic in order to embed the immunologic and epidemiologic changes in any specific geographic Region. According to this, the current study addresses a proposal to modify the Childhood Immunization Schedule in Spain. In order to move from a three plus one schema to a two plus one, we undertake a review of the available literature to explore the immunological and clinical rationale behind this change, including an overview of the potential impact on this schedule of premature infants. Additionally, some recommendations are made regarding those Spanish regions that start hepatitis B vaccination at the newborn period.

In recent years, the performance of semi-supervised learning has been theoretically investigated. However, most of this theoretical development has focussed on binary classification problems. In this paper, we take it a step further by extending the work of Castelli and Cover [1] [2] to the multi-class paradigm. Particularly, we consider the key problem in semi-supervised learning of classifying an unseen instance x into one of K different classes, using a training dataset sampled from a mixture density distribution and composed of l labelled records and u unlabelled examples. Even under the assumption of identifiability of the mixture and having infinite unlabelled examples, labelled records are needed to determine the K decision regions. Therefore, in this paper, we first investigate the minimum number of labelled examples needed to accomplish that task. Then, we propose an optimal multi-class learning algorithm which is a generalisation of the optimal procedure proposed in the literature for binary problems. Finally, we make use of this generalisation to study the probability of error when the binary class constraint is relaxed.

The learning of probability distributions from data is a ubiquitous problem in the fields of Statistics and Artificial Intelligence. During the last decades several learning algorithms have been proposed to learn probability distributions based on decomposable models due to their advantageous theoretical properties. Some of these algorithms can be used to search for a maximum likelihood decomposable model with a given maximum clique size, k, which controls the complexity of the model. Unfortunately, the problem of learning a maximum likelihood decomposable model given a maximum clique size is NP-hard for k > 2. In this work, we propose a family of algorithms which approximates this problem with a computational complexity of O(k · n^2 log n) in the worst case, where n is the number of implied random variables. The structures of the decomposable models that solve the maximum likelihood problem are called maximal k-order decomposable graphs. Our proposals, called fractal trees, construct a sequence of maximal i-order decomposable graphs, for i = 2, ..., k, in k − 1 steps. At each step, the algorithms follow a divide-and-conquer strategy based on the particular features of this type of structures. Additionally, we propose a prune-and-graft procedure which transforms a maximal k-order decomposable graph into another one, increasing its likelihood. We have implemented two particular fractal tree algorithms called parallel fractal tree and sequential fractal tree. These algorithms can be considered a natural extension of Chow and Liu’s algorithm, from k = 2 to arbitrary values of k. Both algorithms have been compared against other efficient approaches in artificial and real domains, and they have shown a competitive behavior to deal with the maximum likelihood problem. Due to their low computational complexity they are especially recommended to deal with high dimensional domains.

[EN]Probability models on permutations associate a probability value to each of the permutations on n items. This paper considers two popular probability models, the Mallows model and the Generalized Mallows model. We describe methods for making inference, sampling and learning such distributions, some of which are novel in the literature. This paper also describes operations for permutations, with special attention in those related with the Kendall and Cayley distances and the random generation of permutations. These operations are of key importance for the efficient computation of the operations on distributions. These algorithms are implemented in the associated R package. Moreover, the internal code is written in C++.

The Linear Ordering Problem is a popular combinatorial optimisation problem which has been extensively addressed in the literature. However, in spite of its popularity, little is known about the characteristics of this problem. This paper studies a procedure to extract static information from an instance of the problem, and proposes a method to incorporate the obtained knowledge in order to improve the performance of local search-based algorithms. The procedure introduced identifies the positions where the indexes cannot generate local optima for the insert neighbourhood, and thus global optima solutions. This information is then used to propose a restricted insert neighbourhood that discards the insert operations which move indexes to positions where optimal solutions are not generated. In order to measure the efficiency of the proposed restricted insert neighbourhood system, two state-of-the-art algorithms for the LOP that include local search procedures have been modified. Conducted experiments confirm that the restricted versions of the algorithms outperform the classical designs systematically. The statistical test included in the experimentation reports significant differences in all the cases, which validates the efficiency of our proposal.

[EN]The Mallows and Generalized Mallows models are compact yet powerful and natural ways of representing a probability distribution over the space of permutations. In this paper we deal with the problems of sampling and learning (estimating) such distributions when the metric on permutations is the Cayley distance. We propose new methods for both operations, whose performance is shown through several experiments. We also introduce novel procedures to count and randomly generate permutations at a given Cayley distance both with and without certain structural restrictions. An application in the field of biology is given to motivate the interest of this model.

[EN]In this paper we deal with probability distributions over permutation spaces. The Probability model in use is the Mallows model. The distance for permutations that the model uses in the Ulam distance.

[EN]In this paper we deal with distributions over permutation spaces. The Mallows model is the mode l in use. The associated distance for permutations is the Hamming distance.

Recently, probability models on rankings have been proposed in the field of estimation of distribution algorithms in order to solve permutation-based combinatorial optimisation problems. Particularly, distance-based ranking models, such as Mallows and Generalized Mallows under the Kendall’s-t distance, have demonstrated their validity when solving this type of problems. Nevertheless, there are still many trends that deserve further study. In this paper, we extend the use of distance-based ranking models in the framework of EDAs by introducing new distance metrics such as Cayley and Ulam. In order to analyse the performance of the Mallows and Generalized Mallows EDAs under the Kendall, Cayley and Ulam distances, we run them on a benchmark of 120 instances from four well known permutation problems. The conducted experiments showed that there is not just one metric that performs the best in all the problems. However, the statistical test pointed out that Mallows-Ulam EDA is the most stable algorithm among the studied proposals.

We report on near normal far- and mid-infrared emission and reflectivity of NdMnO₃ perovskite from room temperature to sample decomposition above 1800 K. At 300 K the number infrared active phonons is in close agreement with the 25 calculated for the orthorhombic D¹⁶2h-Pbnm (Z=4) space group. Their number gradually decreases as we approach the temperature of orbital disorder at ~1023 K where the orthorhombic O' lower temperature cooperative phase coexists with the cubic orthorhombic O. At above ~1200 K, the three infrared active phonons coincide with the expected for cubic Pm-3m (Z=1) in the high temperature insulating regime. Heating samples in dry air triggers double exchange conductivity by Mn³⁺ and Mn⁴⁺ ions and a small polaron mid-infrared band. Fits to the optical conductivity single out the octahedral antisymmetric and symmetric vibrational modes as main phonons in the electron-phonon interactions at 875 K. For 1745 K, it is enough to consider the symmetric stretching internal mode. An overdamped defect induced Drude component is clearly outlined at the highest temperatures. We conclude that Rare Earth manganites eg electrons are prone to spin, charge, orbital, and lattice couplings in an intrinsic orbital distorted perovskite lattice favoring embryonic low energy collective excitations., Facultad de Ciencias Exactas, Centro de Química Inorgánica

Producción Científica, La ruptura de los aneurismas de aorta abdominal representa un evento clínico muy importante debido a su alta tasa de mortalidad. Los indicadores empleados actualmente para decidir el tratamiento a pacientes con aneurismas son el diámetro máximo transversal y la tasa de crecimiento, los que pueden ser considerados insuficientes, pues no tienen una base teórica físicamente fundamentada. En el presente artículo se definen los fundamentos para el diseño de una herramienta informática para PC que permita predecir, con suficiente precisión para ser clínicamente relevante, el riesgo de ruptura de aneurismas de aorta abdominal sobre bases personalizadas del paciente. La herramienta consta de 3 módulos, que están diseñados para procesar toda la información del paciente e integrarla mediante un modelo que incorpora la interrelación de los factores biomecánicos de diferentes naturalezas (biológicos, estructurales y geométrico) y escalas (temporal y dimensional), con el objetivo de calcular un indicador numérico y personalizado del riesgo de ruptura. Esta herramienta debe constituir un elemento auxiliar del facultativo médico en la toma de decisiones respecto del tratamiento adecuado a pacientes con aneurisma

We report on the far- and mid-infrared reflectivity of NdMnO₃ from 4 to 300 K. Two main features are distinguished in the infrared spectra: active phonons in agreement with expectations for the orthorhombic D¹⁶2h-Pbnm (Z = 4) space group remaining constant down to 4 K and a well defined collective excitation in the THz region due to eg electrons in a d-orbital fluctuating environment. We trace its origin to the NdMnO₃ high-temperature orbital disordered intermediate phase not being totally dynamically quenched at lower temperatures. This results in minute orbital misalignments that translate into randomized non-static eg electrons within orbitals yielding a room-temperature collective excitation. Below TN ∼ 78 K, electrons gradually localize, inducing long-range magnetic order as the THz band condenses into two modes that emerge pinned to the A-type antiferromagnetic order. They harden simultaneously down to 4 K, obeying power laws with TN as the critical temperature and exponents β ∼ 0.25 and β ∼ 0.53, as for a tri-critical point and Landau magnetic ordering, respectively. At 4 K they match known zone center spin wave modes. The power law dependence is concomitant with a second order transition in which spin modes modulate orbital instabilities in a magnetoelectric hybridized orbital-charge-spin-lattice scenario. We also found that phonon profiles also undergo strong changes at TN ∼ 78 K due to magnetoelasticity., Facultad de Ciencias Exactas, Centro de Química Inorgánica

Methods for generating a new population are a fundamental component of estimation of distribution algorithms (EDAs). They serve to transfer the information contained in the probabilistic model to the new generated population. In EDAs based on Markov networks, methods for generating new populations usually discard information contained in the model to gain in efficiency. Other methods like Gibbs sampling use information about all interactions in the model but are computationally very costly. In this paper we propose new methods for generating new solutions in EDAs based on Markov networks. We introduce approaches based on inference methods for computing the most probable configurations and model-based template recombination. We show that the application of different variants of inference methods can increase the EDAs’ convergence rate and reduce the number of function evaluations needed to find the optimum of binary and non-binary discrete functions.

In this paper we empirically investigate which are the structural characteristics that can help to predict the complexity of NK-landscape instances for estimation of distribution algorithms. To this end, we evolve instances that maximize the estimation of distribution algorithm complexity in terms of its success rate. Similarly, instances that minimize the algorithm complexity are evolved. We then identify network measures, computed from the structures of the NK-landscape instances, that have a statistically significant difference between the set of easy and hard instances. The features identified are consistently significant for different values of N and K.