DEAnER: An Effective Assessment Model

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Asymptotic Dynamics of Breathers in Fermi-Pasta-Ulam Chains

We study the asymptotic dynamics of breathers in finite Fermi-Pasta-Ulam chains at zero and non-zero temperatures. While such breathers are essentially stationary and very long-lived at zero temperature, thermal fluctuations tend to lead to breather motion and more rapid decay

To explore or to exploit? Learning humans' behaviour to maximize interactions with them

Assume a robot operating in a public space (e.g., a library, a museum) and serving visitors as a companion, a guide or an information stand. To do that, the robot has to interact with humans, which presumes that it actively searches for humans in order to interact with them. This paper addresses the problem how to plan robot's actions in order to maximize the number of such interactions in the case human behavior is not known in advance. We formulate this problem as the exploration/exploitation problem and design several strategies for the robot. The main contribution of the paper than lies in evaluation and comparison of the designed strategies on two datasets. The evaluation shows interesting properties of the strategies, which are discussed

Cyclic behavior of ultra-high performance fiber reinforced concrete beam-column joint

[EN] Ultra-high performance fiber reinforced concrete (UHPFRC) is a unique class of fiber-reinforced concrete featuring ultra-high compressive strength and ductil e tensile strain hardening behavior, accompanied by multiple narrow cracking. Although many studies have confirmed its superior mechanical and damage tolerance properties under monotonic or blast loading, limited research has been carried out on the cyclic performance of UHPFRC structural members. This paper proposes the use of UHPFRC to improve the cyclic performance of structural elements. An experimental program was carried out on a large number of UHPFRC beam-column joint specimens under a cyclic lateral load. After the cyclic loading test, the following results were obtained: (a) hysterical performance, (b) maximum load, (c) maximum displacement, (d) the maximum energy dissipation (measured by hysteresis cycles), (e) stiffness degradation, (f) the cracking pattern, and (g) the cracking area. The analysis showed that UHPFRC specimens have at least 157% higher energy dissipation than nonfiber conventional reinforced concrete (RC). The initial stiffness of UHPFRC specimens without fibers (NF) was at least 23% higher than the RC specimen. For UHPFRC with fiber, initial stiffness was at least 45% higher than RC specimen.This work was supported by Cementos Argos, Colciencias and the Pontificia Universidad Javeriana, Bogotá (Colombia).Sarmiento, PA.; Torres Górriz, B.; Ruiz, DM.; Alvarado Vargas, YA.; Gasch, I.; Machuca, AF. (2019). Cyclic behavior of ultra-high performance fiber reinforced concrete beam-column joint. Structural Concrete. 20(1):348-360. https://doi.org/10.1002/suco.201800025S34836020

Mortalidad de equinos por Trypanosoma evansi en Argentina. Diagnóstico parasitológico y molecular

Trypanosoma evansi is the causative agent of trypanosomosis and affects a wide variety of domestic and wild animals, with horses being the main affected. The objective of this work is to describe an outbreak of trypanosomosis due to T. evansi in twenty (20) horses with symptoms characterized by progressive weight loss, loss of appetite, intermittent hyperthermia, weakness, lymphoadenomegaly, pale mucous membranes, nasal secretions and epiphora, edemas in the chest area, abdomen and later members. The diagnosis was positive for T. evansi. The treatment consisted of diminacin aceturate without satisfactory results. This work is the first report of death of horses by T. evansi with parasitological and molecular diagnosis in the town of Monte Caseros, Corrientes, Argentina.Trypanosoma evansi, el agente causal de la tripanosomosis, afecta a una amplia variedad de animales domésticos y silvestres, siendo los equinos los principales enfermados. El objetivo de este trabajo fue describir un brote de tripanosomosis por T. evansi en veinte (20) equinos con sintomatología caracterizada por una progresiva pérdida de peso, inapetencia, hipertermia intermitente, debilidad, linfoadenomegalia, mucosas pálidas, secreciones nasales, epífora, edemas en zona de pecho, abdomen y miembros posteriores. El diagnóstico parasitológico y molecular fue positivo para T. evansi. Los animales fueron tratados con aceturato de diminacina sin resultados satisfactorios. Este trabajo es el primer reporte de mortandad de equinos por T. evansi con diagnóstico parasitológico y molecular, en la localidad de Monte Caseros, Corrientes, Argentina

La proteína de estrés, heat shock cognate (hsc70) se sobreexpresa en osteoblastos sometidos a centrifugación

Antecedentes. El osteoblasto tiene la capacidadde estimular la neoformación del tejido óseo,mediante la síntesis de proteínas tales como lasproteínas morfogenéticas, factores de crecimientoy proteínas colágenas y no colágenas. A suvez, indirectamente controla los procesos dereabsorción sintetizando otra serie de proteínasestimuladoras de la actividad osteoclastogénica.Objetivo. El propósito de este trabajo de investigaciónfue analizar la expresión de la proteínade choque térmico HSC70 en un cultivo primariode osteoblastos, después de someterlo a una fuerzatensil mediante centrifugación, determinandoel patrón de proteínas mediante análisiselectroforético.Material y métodos. A partir de cráneos deratones lactantes ICR se obtuvieron cultivos decélulas con características morfológicas tipofibroblastoide, con prolongaciones alargadas ycitoplasmas ligeramente cuboidales que sugiereun cultivo enriquecido de osteoblastos; loscuales fueron sometidos a centrifugación y seanalizó por inmunocitoquímica, electroforesis yWestern blot la expresión diferencial de la proteínaHSC70.Resultados. La técnica de electroforesis SDSPAGEunidimensional no permitió determinardiferencias en el patrón de corrido entreosteoblastos tratados respecto a los no tratadoscon la fuerza tensil. Sin embargo, la proteínaHSC70 se sobre-expresa en osteoblastos sometidosa centrifugación analizada mediante la técnica de Western blot e inmunohistoquímica.Conclusión. Aunque la electroforesis no determinódiferencias en el patrón de corrido,la proteína de estrés HSC70 se sobre-expresóen osteoblastos sometidos a centrifugaciónanalizada mediante la técnica de Western blote inmunocitoquímica, sugiriendo que es importanteen este tipo de estrés

Irreversible and reversible modes of operation of deterministic ratchets

We discuss a problem of optimization of the energetic efficiency of a simple rocked ratchet. We concentrate on a low-temperature case in which the particle's motion in a ratchet potential is deterministic. We show that the energetic efficiency of a ratchet working adiabatically is bounded from above by a value depending on the form of ratchet potential. The ratchets with strongly asymmetric potentials can achieve ideal efficiency of unity without approaching reversibility. On the other hand we show that for any form of the ratchet potential a set of time-protocols of the outer force exist under which the operation is reversible and the ideal value of efficiency is also achieved. The mode of operation of the ratchet is still quasistatic but not adiabatic. The high values of efficiency can be preserved even under elevated temperatures

Enhanced Pulse Propagation in Non-Linear Arrays of Oscillators

The propagation of a pulse in a nonlinear array of oscillators is influenced by the nature of the array and by its coupling to a thermal environment. For example, in some arrays a pulse can be speeded up while in others a pulse can be slowed down by raising the temperature. We begin by showing that an energy pulse (1D) or energy front (2D) travels more rapidly and remains more localized over greater distances in an isolated array (microcanonical) of hard springs than in a harmonic array or in a soft-springed array. Increasing the pulse amplitude causes it to speed up in a hard chain, leaves the pulse speed unchanged in a harmonic system, and slows down the pulse in a soft chain. Connection of each site to a thermal environment (canonical) affects these results very differently in each type of array. In a hard chain the dissipative forces slow down the pulse while raising the temperature speeds it up. In a soft chain the opposite occurs: the dissipative forces actually speed up the pulse while raising the temperature slows it down. In a harmonic chain neither dissipation nor temperature changes affect the pulse speed. These and other results are explained on the basis of the frequency vs energy relations in the various arrays