Characterization of strain PTV-2 USA/IA65463/2014 and strain PTV-11 USA/IA09592/2013 of Teschovirus A: Experimental inoculation, distribution of nucleic acids and development of Teschovirus encephalomyelitis

Teschovirus A (previously Porcine teschovirus; PTV) is the etiologic agent of Teschovirus encephalomyelitis (TE). Historically, PTV-1 has been recognized as one of the most pathogenic serotypes, although other serotypes have been described to cause TE. Hence, most information about the pathogenicity, epidemiology and control of disease relies on data from studies involving PTV-1. In recent years, two cases submitted to the Iowa State University Veterinary Diagnostic Laboratory with a history of polioencephalitis and/or myelitis were identified and genomic sequencing characterized these isolates as (sero)types PTV-2 and PTV-11. Although multiple serotypes have been identified and genetically characterized, the neuropathogenicity of some of these serotypes has not been fully elucidated. To assess these isolates, we developed an experimental model to determine the neuropathogenicity of the PTV-2 and PTV-11 isolates and observed that both isolates caused histological lesions and clinical disease consistent with TE in cesarean-derived colostrum-deprived pigs. Furthermore, PTV RNA was detected in different tissues, serum and feces in all inoculated animals by RT-qPCR. The experimental approach used in this research permitted to develop a successful platform to induce clinical disease. This is the first description of a neuropathogenic PTV-11 strain in the U.S. and the first experimental inoculation using a PTV-2 autochthonous U.S. strain after the initial description of PTV-2 strain O3b made by Long at al. in 1966. This is also the first assessment of the viral shedding, viremia and distribution by real time RT-qPCR of nucleic acids of PTV-2 and PTV-11 in experimentally infected pigs with Teschovirus encephalomyelitis

Thermodynamics of the classical spin-ice model with nearest neighbour interactions using the Wang-Landau algorithm

In this article we study the classical nearest-neighbour spin-ice model (nnSI) by means of Monte Carlo simulations, using the Wang-Landau algorithm. The nnSI describes several of the salient features of the spin-ice materials. Despite its simplicity it exhibits a remarkably rich behaviour. The model has been studied using a variety of techniques, thus it serves as an ideal benchmark to test the capabilities of the Wang Landau algorithm in magnetically frustrated systems. We study in detail the residual entropy of the nnSI and, by introducing an applied magnetic field in two different crystallographic directions ([111] and [100],) we explore the physics of the kagome-ice phase, the transition to full polarisation, and the three dimensional Kasteleyn transition. In the latter case, we discuss how additional constraints can be added to the Hamiltonian, by taking into account a selective choice of states in the partition function and, then, show how this choice leads to the realization of the ideal Kasteleyn transition in the system.Comment: 9 pages, 9 figure

Mutual information and sensitivity analysis for feature selection in customer targeting: a comparative study

WOS:000454945400004Feature selection is a highly relevant task in any data-driven knowledge discovery project. The present research focuses on analysing the advantages and disadvantages of using mutual information (MI) and data-based sensitivity analysis (DSA) for feature selection in classification problems, by applying both to a bank telemarketing case. A logistic regression model is built on the tuned set of features identified by each of the two techniques as the most influencing set of features on the success of a telemarketing contact, in a total of 13 features for MI and 9 for DSA. The latter performs better for lower values of false positives while the former is slightly better for a higher false-positive ratio. Thus, MI becomes a better choice if the intention is reducing slightly the cost of contacts without risking losing a high number of successes. However, DSA achieved good prediction results with less features.info:eu-repo/semantics/acceptedVersio

¿Un Arzobispo de Bogotá, Fundador de la Universidad de Córdoba?

Ningun

Boundary conditions and the residual entropy of ice systems

We would like to acknowledge financial support from CONICET (Argentina) and from ANPCYT (Argentina) via Grant No. PICT-2013-2004.In this work we address the classical statistical mechanical problem of calculating the residual entropy of ice models. The numerical work found in the literature is usually based on extrapolating to infinite-size results obtained for finite-size systems with periodic boundary conditions. In this work we investigate how boundary conditions affect the calculation of the residual entropy for square, cubic, and hexagonal lattices using periodic, antiperiodic, and open boundary conditions. We show that periodic boundary conditions lead to noticeable oscillations in the entropy as a function of lattice size, and we calculate in open finite systems the contribution to the entropy from the open boundary. For our calculations we introduce a variation on multicanonical simulation methods that directly calculate the number of states in the ground state without the need of a Hamiltonian.Publisher PDFPeer reviewe

Study of the light-induced metal-insulator transition in SrTiO3 by photoresistance spectroscopy

Photoresistivity and its spectral response has been systematically studied in oxygen deficient SrTiO3 single crystals for a wide range of resistivities, ρ, and carrier densities, n. At roomtemperature we have found a persistent photoresistance that gradually decreases as ρ is diminished or n is increased in addition to relaxation times of seconds to a few minutes suggesting that trapping of carriers is playing a major role. An analysis of the photoresistance excitation spectra shows two distinctive features that are related to the indirect gap of SrTiO3 at (3.25 ± 0.04) eV and to a direct transition at (3.40 ± 0.03) eV. The photoresistive crystals present a temperature dependent resisitivity under illumination that experiences a metal-insulator transition below T ∼ 85 K. Lowtemperature photoresistance spectrum reveals as a suitable technique to understand the origin of this transition, pointing to an enhanced efficiency of the ∼ 3.25 eV gap to promote electrons to the bottom of the conduction band.Fil: Bridoux, German. Universidad Nacional de Tucumán. Facultad de Ciencias Exactas y Tecnología. Departamento de Física. Laboratorio de Física del Solido; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Villafuerte, Manuel Jose. Universidad Nacional de Tucumán. Facultad de Ciencias Exactas y Tecnología. Departamento de Física. Laboratorio de Física del Solido; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Ferreyra, J. M.. Universidad Nacional de Tucumán. Facultad de Ciencias Exactas y Tecnología. Departamento de Física. Laboratorio de Física del Solido; ArgentinaFil: Bachi, N.. Universidad Nacional de Tucumán. Facultad de Ciencias Exactas y Tecnología. Departamento de Física. Laboratorio de Física del Solido; ArgentinaFil: Figueroa, C. A.. Universidad Nacional de Tucumán. Facultad de Ciencias Exactas y Tecnología. Departamento de Física. Laboratorio de Física del Solido; ArgentinaFil: Heluani, S. P.. Universidad Nacional de Tucumán. Facultad de Ciencias Exactas y Tecnología. Departamento de Física. Laboratorio de Física del Solido; Argentin

Key Role of Oxygen-Vacancy Electromigration in the Memristive Response of Ferroelectric Devices

Ferroelectric memristors are intensively studied due to their potential implementation in data storage and processing devices. In this work we show that the memristive behavior of metal-ferroelectric-oxide-metal devices relies on the competition of two effects: the modulation of metal-ferroelectric interface barriers by the switchable ferroelectric polarization and the electromigration of oxygen vacancies, with the depolarizing field playing a fundamental role in the latter. We simulate our experimental results with a phenomenological model that includes both effects and we reproduce several nontrivial features of the electrical response, including resistance relaxations observed after external poling. Besides providing insight into the underlying physics of these complex devices, our work suggests that it is possible to combine nonvolatile and volatile resistive changes in single ferroelectric memristors, an issue that could be useful for the development of neuromorphic devices.Fil: Ferreyra, Cristian Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Unidad Ejecutora Instituto de Nanociencia y Nanotecnología. Unidad Ejecutora Instituto de Nanociencia y Nanotecnología - Nodo Constituyentes | Comisión Nacional de Energía Atómica. Unidad Ejecutora Instituto de Nanociencia y Nanotecnología. Unidad Ejecutora Instituto de Nanociencia y Nanotecnología - Nodo Constituyentes; ArgentinaFil: Rengifo Morocho, Miguel Andrés. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Unidad Ejecutora Instituto de Nanociencia y Nanotecnología. Unidad Ejecutora Instituto de Nanociencia y Nanotecnología - Nodo Constituyentes | Comisión Nacional de Energía Atómica. Unidad Ejecutora Instituto de Nanociencia y Nanotecnología. Unidad Ejecutora Instituto de Nanociencia y Nanotecnología - Nodo Constituyentes; ArgentinaFil: Sanchez, Maria Jose. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Unidad Ejecutora Instituto de Nanociencia y Nanotecnología. Unidad Ejecutora Instituto de Nanociencia y Nanotecnología - Nodo Bariloche | Comisión Nacional de Energía Atómica. Unidad Ejecutora Instituto de Nanociencia y Nanotecnología. Unidad Ejecutora Instituto de Nanociencia y Nanotecnología - Nodo Bariloche; ArgentinaFil: Everhardt, Arnoud S.. University of Groningen; Países BajosFil: Noheda, Beatriz. University of Groningen; Países BajosFil: Rubi, Diego. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Unidad Ejecutora Instituto de Nanociencia y Nanotecnología. Unidad Ejecutora Instituto de Nanociencia y Nanotecnología - Nodo Constituyentes | Comisión Nacional de Energía Atómica. Unidad Ejecutora Instituto de Nanociencia y Nanotecnología. Unidad Ejecutora Instituto de Nanociencia y Nanotecnología - Nodo Constituyentes; Argentin

Communicative interaction in natural sciences lessons. A didactic analysis based on discursive circuits

En este trabajo se discute el rol de la comunicación en el aula de ciencias y se delimita una forma de análisis relacionada con circuitos de interacción discursiva. Se comparan tres tipos de circuitos para clases de ciencias experimentales: exposición abierta, diálogo guiado e indagación dialógica problematizadora. Los datos resumen los registros de un grupo de investigaciones interpretativas desarrolladas por el equipo en los últimos diez años, las cuales analizan el diálogo asociado a temas de ciencias y ciclos de actividad. Se presenta la escala de análisis resultante y los tipos de secuencia de intervenciones de docentes y alumnos. Desde las mismas se modelizan circuitos de comunicación que van desde la clase tradicional a una constructivista.Se concluye respecto a la necesidad de incluir la problemática de la comunicación en el aula a lo largo de la práctica educativa y de los procesos de formación docente, haciéndola formar parte tanto del diseño, como del desarrollo y evaluación de la tarea docente.This work argues the role of communication in natural sciences classrooms and delimits a way of analysis in relation to interactive discursive circuits. Three types of circuits for experimental sciences lessons are compared: open exposition, guided dialog and problematic dialogic inquiry. The data summary the records of a group of interpretative research developed by the team in the last years ten years, which analyses the dialogue associated with science topics and cycles of activity. The resulting scale of analysis and types of intervention sequences held by teachers and students are presented. Based on them, communication circuits are modeled ranging from the traditional classroom to a constructivist one. It is concluded in relation to the need of including the problem of communication in the classroom throughout the educational practice and the processes of teacher training, making it part of the design, development and evaluation of the teaching task