Extended star formation history of the star cluster NGC 2154 in the Large Magellanic Cloud

The colour-magnitude diagram (CMD) of the intermediate-age Large Magellanic Cloud star cluster NGC 2154 and its adjacent field has been analysed using Padova stellar models to determine the cluster´s fundamental parameters and its star formation history. Deep BR CCD photometry, together with synthetic CMDs and integrated luminosity functions, has allowed us to infer that the cluster experienced an extended star formation period of about 1.2 Gyr, which began approximately 2.3 Gyr ago and ended 1.1 Gyr ago. However, the physical reality of such a prolonged period of star formation is questionable, and could be the result of inadequacies in the stellar evolutionary tracks themselves. A substantial fraction of binaries (70 per cent) seems to exist in NGC 2154.Fil: Baume, Gustavo Luis. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Astrofísica La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas. Instituto de Astrofísica La Plata; ArgentinaFil: Carraro, Giovanni. Università di Padova; ItaliaFil: Costa, E.. Universidad de Chile; ChileFil: Mendez, R. A.. Universidad de Chile; ChileFil: Girardi, L.. Osservatorio Astronomico di Padova; Itali

Evaluation of corrosion resistance of aluminum-based alloys in bioethanol produced in Misiones

Nowadays, biofuels represent a large part of renewable energies destined to substitute fossil fuels, and to reduce the negative impact on the environment. Bioethanol is obtained by alcoholic fermentation, and is used pure or mixed with other petroleum derivatives as fuel. Use, manipulation, storage and transport of these substances, at any scale, demand the implementation of materials, such as aluminum, that has excellent mechanical properties, as well as low density. Generally, these characteristics are improved by alloying aluminum with silicon (in order to decrease the thermal expansion coefficient and increase wear resistance) and magnesium (to increase hardness of the material). Potentiodynamic polarization and electrochemical spectroscopy impedance techniques were used on this research, in order to determine the corrosion resistance of Al-10 wt.%Si, Al-12 wt.%Si, Al-2%Mg and Al-4 wt.%Mg alloys in an alcoholic electrolyte (bioethanol of Misiones province, Argentina industry). Comparing to pure aluminum, aluminum-silicon alloys presented better corrosion resistance. On the other hand, aluminum-magnesium alloys didn?t have such improvement. By using optical metallographic microscope, no differences were found on the surfaces of alloys after being exposed to the alcoholic electrolyte.Fil: Kramer, Gustavo Raul. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnológico Nordeste. Instituto de Materiales de Misiones; Argentina. Universidad Nacional de Misiones; ArgentinaFil: Mendez, Claudia Marcela. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnológico Nordeste. Instituto de Materiales de Misiones; Argentina. Universidad Nacional de Misiones; ArgentinaFil: Ares, Alicia Esther. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnológico Nordeste. Instituto de Materiales de Misiones; Argentina. Universidad Nacional de Misiones; Argentin

El sistema de detracciones en el área contable de la empresa Biomega S.A.C. Ancash - Chimbote - 2014

La presente investigación lleva por título El Sistema de Detracciones en el Área Contable de la Empresa Biomega S.A.C. Ancash Chimbote 2014, tuvo como objetivo principal determinar el nivel del sistema de detracciones en el área contable de la empresa Biomega S.A.C. Ancash Chimbote 2014, el tipo de investigación fue básica de nivel descriptivo, la investigación tiene un diseño no experimental descriptivo simple con un enfoque cuantitativo y tuvo como población y muestra a 32 trabajadores. La técnica utilizada fue la encuesta y el instrumento utilizado fue un cuestionario de 26 preguntas graduadas en escala Likert, se demostró la validez y fiabilidad mediante la técnica de opinión de expertos y alfa de Cronbach. La presente investigación finalmente llegó a la conclusión que el 100% de los trabajadores perciben que el sistema de detracciones presenta un nivel moderado

Design and optimization of an opto-acoustic sensor based on porous silicon phoxonic crystals

We present the theoretical study of an opto-acoustic microdevice, a phoxonic crystal, made of porous silicon with a specific acoustic response in the range of tens of MHz and optical response in the visible and near-infrared range. We propose to control the opto-acoustic response of this device by spatially modulating the microstructure porosity. Based on this study, a multilayer microcavity is designed to have a strong coupling between the acoustic and optical response. The coupling mechanism is generated by exploiting the structural resonance due to the acoustic waves which produce maximum mechanical strains at the center of the cavity. The associated mechanical deformations of the central cavity change the optical response of the multilayer, allowing the mechanical response to be detected using optical techniques. In a phoxonic crystal, the acoustic and optic central gap frequencies are determined by the multilayer configuration which imposes a fixed relation between both resonant frequencies. This feature establishes a challenge for the microdevice design. To mitigate this problem, two microcavities, one inside the other in a matryoshka-like configuration is here proposed, placing an optical microcavity into the spacer of an acoustic microcavity. Consequently, the localized acoustic field generates a high perturbation of the optical microcavity structure. The optical microcavity is tuned at near-infrared frequencies, while the larger acoustic microcavity resonates at acoustic frequencies of the order of tens of MHz. The microdevice is designed to display a high optical response induced by acoustic deformation. Optical sensitivity to this effect is used to design a multiparametric sensor. Thanks to the porous structure of the device, it is possible to build a transducer sensitive to the presence of analytes in the environment that affect both its mechanical and optical response.Fil: Forzani, Luisina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Centro de Investigaciones en Métodos Computacionales. Universidad Nacional del Litoral. Centro de Investigaciones en Métodos Computacionales; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Física del Sur. Universidad Nacional del Sur. Departamento de Física. Instituto de Física del Sur; ArgentinaFil: Mendez, Carlos Gustavo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Centro de Investigaciones en Métodos Computacionales. Universidad Nacional del Litoral. Centro de Investigaciones en Métodos Computacionales; ArgentinaFil: Urteaga, Raul. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Física del Litoral. Universidad Nacional del Litoral. Instituto de Física del Litoral; ArgentinaFil: Huespe, Alfredo Edmundo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Centro de Investigaciones en Métodos Computacionales. Universidad Nacional del Litoral. Centro de Investigaciones en Métodos Computacionales; Argentin

Fondo de Empleados para el Complejo Carcelario y Penitenciario Metropolitano de Cúcuta "COCUC"

Este proyecto consiste en la creación de un fondo de empleados para el complejo carcelario y penitenciario metropolitano de cúcuta. Para la ejecución del proyecto se realizaron diversas labores de campo como encuestas, donde se pudo evidenciar la viabilidad de la propuesta. También se capacito en economía solidaria al personal interesados en conformar el fondo de empleados. Además se gestiono el proceso legal de la constitución y se inicio su funcionamiento, colocando al servicio de los asociados diferentes modalidades de ahorro y crédito, a fin de generar excedentes para desarrollo del objeto social del fondo de empleados

Endoscopic Management of Cavernous Carotid Surgical Complications: Evaluation of a Simulated Perfusion Model

Objective—Endoscopic surgical treatment of pituitary tumors, lateral invading tumors, or aneurysms requires surgeons to operate adjacent to the cavernous sinus. During these endoscopic endonasal procedures, the carotid artery is vulnerable to surgical injury at its genu. The objective of this simulation model was to evaluate trainees regarding management of a potentially lifethreatening vascular injury. Methods—Cadaveric heads were prepared in accordance with the Oregon Health & Science University body donation program. An endoscopic endonasal approach was used, and a perfusion pump with a catheter was placed in the ipsilateral common carotid artery at its origin in the neck. Learners used a muscle graft to establish vascular control and were evaluated over 3 training sessions. Simulation assessment, blood loss during sessions, and performance metric data were collected for learners. Results—Vascular control was obtained at a mean arterial pressure of 65 mm Hg using a muscle graft correctly positioned at the arteriotomy site. Learners improved over the course of training, with senior residents (n = 4) performing better across all simulation categories (situation awareness, decision making, communications and teamwork, and leadership); the largest mean difference was in communication and teamwork. Additionally, learner performance concerning blood loss improved between sessions (t = 3.667, P \u3c 0.01). Conclusions—In this pilot endoscopic endonasal simulation study, we successfully demonstrate a vascular complication perfusion model. Learners were able to gain direct applicable expertise in endoscopic endonasal techniques, instrumentation use, and teamwork required to optimize the technique. Learners gained skills of vascular complication management that transcend this model

An invertebrate smooth muscle with striated muscle myosin filaments

Muscle tissues are classically divided into two major types, depending on the presence or absence of striations. In striated muscles, the actin filaments are anchored at Z-lines and the myosin and actin filaments are in register, whereas in smooth muscles, the actin filaments are attached to dense bodies and the myosin and actin filaments are out of register. The structure of the filaments in smooth muscles is also different from that in striated muscles. Here we have studied the structure of myosin filaments from the smooth muscles of the human parasite Schistosoma mansoni. We find, surprisingly, that they are indistinguishable from those in an arthropod striated muscle. This structural similarity is supported by sequence comparison between the schistosome myosin II heavy chain and known striated muscle myosins. In contrast, the actin filaments of schistosomes are similar to those of smooth muscles, lacking troponin-dependent regulation. We conclude that schistosome muscles are hybrids, containing striated muscle-like myosin filaments and smooth muscle-like actin filaments in a smooth muscle architecture. This surprising finding has broad significance for understanding how muscles are built and how they evolved, and challenges the paradigm that smooth and striated muscles always have distinctly different components

Arquitecturas y modelos de programación en computación grid

El crecimiento permanente en computación paralela y sus arquitecturas en hardware y software, han generado nuevos retos para los desarrolladores de software. La computación Grid cada vez toma más relevancia en los problemas que requieren soluciones de multiprocesamiento y grandes cargas de trabajo; en consecuencia los modelos de programación deben adaptarse a estos desarrollos para que aprovechen y soporten las características de paralelismo, distribución, transparencia, heterogeneidad, rendimiento y procesamiento. En este artículo se analizan los principales modelos de programación para computación Grid, así como el uso de librerías y frameworks que pueden ser adaptados sobre estas arquitecturas