High-energy signatures of binary systems of supermassive black holes

Context. Binary systems of supermassive black holes are expected to be strong sources of long gravitational waves prior to merging. These systems are good candidates to be observed with forthcoming space-borne detectors. Only a few of these systems, however, have been firmly identified to date. Aims. We aim at providing a criterion for the identification of some supermassive black hole binaries based on the characteristics of the high-energy emission of a putative relativistic jet launched from the most massive of the two black holes. Methods. We study supermassive black hole binaries where the less massive black hole has carved an annular gap in the circumbinary disk, but nevertheless there is a steady mass flow across its orbit. Such a perturbed disk is hotter and more luminous than a standard thin disk in some regions. Assuming that the jet contains relativistic electrons, we calculate its broadband spectral energy distribution focusing on the inverse Compton up-scattering of the disk photons. We also compute the opacity to the gamma rays produced in the jet by photon annihilation with the disk radiation and take into account the effects of the anisotropy of the target photon field as seen from the jet. Results. We find that the excess of low-energy photons radiated by the perturbed disk causes an increment in the external Compton emission from the jet in the X-ray band, and a deep absorption feature at energies of tens of TeVs for some sets of parameters. According to our results, observations with Cherenkov telescopes might help in the identification of supermassive black hole binaries, especially those black hole binaries that host primaries from tens to hundreds of million of solar masses.Comment: 12 pages, 11 figures, accepted for publication in Astronomy & Astrophysic

What is a scientific experiment?: The impact of a professional development course on teachers’ ability to design an inquiry-based science curriculum

Designing inquiry-based science lessons can be a challenge for secondary school teachers. In this study we evaluated the development of in-service teachers’ lesson plans as they took part in a 10-month professional development course in Peru which engaged teachers in the design of inquiry-based lessons. At the beginning, most teachers designed either confirmatory or structured inquiry activities. As the course progressed, however, they started designing guided and open inquiry lesson plans. We found four factors that accounted for this change: re-evaluating the need for lab materials, revising their views on the nature of science, engaging in guided and open inquiry activities themselves, and trying out inquiry-based lessons with their own students. Our results point to the importance of engaging teachers in prolonged and varied opportunities for inquiry as part of teacher education programs in order to achieve the challenge of changing teachers’ views and practices in science education.Fil: Pérez, María del Carmen B.. Universidad de Piura; PerúFil: Furman, Melina Gabriela. Universidad de San Andrés. Escuela de Educación; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Applying MDE tools to defining domain specific languages for model management

In the model driven engineering (MDE), modeling languages play a central role. They range from the most generic languages such as UML, to more individual ones, called domain-specific modeling languages (DSML). These languages are used to create and manage models and must accompany them throughout their life cycle and evolution. In this paper we propose a domain-specific language for model management, to facilitate the user's task, developed with techniques and tools used in the MDE paradigm.Fil: Pérez, Gabriela. Universidad Nacional de la Plata. Facultad de Informática. Laboratorio de Investigación y Formación en Informática Avanzada; ArgentinaFil: Irazábal, Jerónimo. Universidad Nacional de la Plata. Facultad de Informática. Laboratorio de Investigación y Formación en Informática Avanzada; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Pons, Claudia Fabiana. Universidad Nacional de la Plata. Facultad de Informática. Laboratorio de Investigación y Formación en Informática Avanzada; Argentina. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas; ArgentinaFil: Giandini, Roxana Silvia. Universidad Nacional de la Plata. Facultad de Informática. Laboratorio de Investigación y Formación en Informática Avanzada; Argentin

Technical efficiency of dairy farms in Uruguay : a stochastic production frontier analysis

The productivity of Uruguayan dairy farms has been consistently growing for the last 40 years. This process has implied the adoption of new technologies which have had significant effects on the production system. The efficiency with which available technologies are used influence output growth. Hence, assuring and enhancing dairy farms’ productivity and efficiency represent an important challenge to improve the competitiveness of the sector and achieve sustained economic growth. The overall objective of this study is to analyze the efficiency performance of dairy farms in Uruguay. Using a cross-sectional database, this study estimates a Cobb-Douglas stochastic production frontier and technical inefficiency model for dairy farms to determine the effect of each input on the production frontier and the principal factors that explain differences in farm efficiency. Results show that the number of milking cows has the highest effect on production, followed by the total consumption of feed, including concentrated feed, hay and silage. Although veterinary, agronomic and accounting assistance matter, the major determinants of efficiency differences are farmers’ specialization in dairy farming and the usage of artificial insemination. Overall, farm profiles indicate that those in the high efficiency group achieve a higher level of milk production than those less efficient; and they produce under a more intensive production system than farmers in low efficiency group

Senecio bonariensis Hook. & Arn. promising arsenic phytoextractor from water in laboratory and field trials

The use of plant species to cleanse groundwater with excessive concentrations of arsenic (As) derived from contact with weathered materials has become a valuable option to treat it. The aim of this work was to analyze the bioaccumulation capacity of As of Senecio bonariensis (Asteraceae) through controlled laboratory tests and uncontrolled trials in the field in order to generate a low cost method applicable in rural areas that do not have systems of water treatments. Plants collected from the natural environment were arranged in hydroponic crops under controlled and uncontrolled conditions, in the first case with increasing concentrations of As for 45 days, and in the second, with a constant concentration of As for a period in a range between 45 and 90 days. The plants were processed and dried for the measurement of As. In both tests, in all the samples there was a noticeable accumulation of As, generally greater in roots than in leaves. Under controlled conditions the plants accumulated more As in relation to greater concentration of this element in the water. In all the trials a high bioaccumulation of As was found, which turns the plant into a hyperaccumulator. Due to the ability of S. bonariensis to accumulate As, and even more because of the great biomass produced by this species, it becomes an excellent one to be used for the remediation of arsenical waters.Fil: Pérez Cuadra, Vanesa. Universidad Nacional del Sur. Departamento de Biología, Bioquímica y Farmacia. Laboratorio de Plantas Vasculares; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Ciencias Biológicas y Biomédicas del Sur. Universidad Nacional del Sur. Departamento de Biología, Bioquímica y Farmacia. Instituto de Ciencias Biológicas y Biomédicas del Sur; ArgentinaFil: Cambi, Viviana Nora. Universidad Nacional del Sur. Departamento de Biología, Bioquímica y Farmacia. Laboratorio de Plantas Vasculares; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Ciencias Biológicas y Biomédicas del Sur. Universidad Nacional del Sur. Departamento de Biología, Bioquímica y Farmacia. Instituto de Ciencias Biológicas y Biomédicas del Sur; ArgentinaFil: Espósito, Martín Eduardo. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional del Sur. Departamento de Agronomía; ArgentinaFil: Sica, María Gabriela. Universidad Nacional del Sur. Departamento de Biología, Bioquímica y Farmacia. Laboratorio de Plantas Vasculares; ArgentinaFil: Verolo, Magalí. Universidad Nacional del Sur. Departamento de Biología, Bioquímica y Farmacia. Laboratorio de Plantas Vasculares; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Ciencias Biológicas y Biomédicas del Sur. Universidad Nacional del Sur. Departamento de Biología, Bioquímica y Farmacia. Instituto de Ciencias Biológicas y Biomédicas del Sur; ArgentinaFil: Siniscalchi, Amira Gabriela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Planta Piloto de Ingeniería Química. Universidad Nacional del Sur. Planta Piloto de Ingeniería Química; ArgentinaFil: Parodi, Elisa Rosalia. Universidad Nacional del Sur. Departamento de Biología, Bioquímica y Farmacia. Laboratorio de Plantas Vasculares; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto Argentino de Oceanografía. Universidad Nacional del Sur. Instituto Argentino de Oceanografía; Argentin

Una vinculación de la matemática escolar y la investigación a través de diseños didácticos con el uso de la tecnología

Este trabajo de investigación ha centrado la atención en generar diseños didácticos que aborden temas del Cálculo y Precálculo del currículo actual, cuyos fundamentos teóricos están basados en investigaciones de corte socioepistemológico favoreciendo el uso inteligente de la tecnología en el aula de matemáticas. En éstos se retomarán aspectos que ayuden a la reconstrucción de significados de tópico matemáticos como el teorema de Thales, el uso de la subtangente para caracterizar una curva (máximos, mínimos y puntos de inflexión) y la noción de acumulación para abordar el área bajo la curva

Medición de indicadores de desarrollo sostenible en Venezuela : propuesta metodológica

En las últimas cuatro décadas se ha propuesto al desarrollo sostenible como la opción viable que asegura crecimiento económico, equidad social y preservación del medio ambiente para satisfacer las necesidades del hombre en el presente y en el futuro. En 1992 las naciones del mundo adoptaron la Agenda 21, un plan a favor del desarrollo sostenible. En dicha agenda se expresa la necesidad de monitorear la evolución de este tipo de desarrollo a través del uso de indicadores. En este trabajo se presenta una recopilación de experiencias en Venezuela en la medición del desarrollo sostenible a través del uso de indicadores, y se presentan una propuesta metodológica basada en técnicas estadísticas para la obtención de un indicador de desarrollo sostenible para este país.During the last four decades it has been proposed sustainable development as a viable option for ensuring economic growth, social equity and environment preservation in order to meet human needs in the present and in the future. In 1992 the world's nations had adopted Agenda 21, a plan for the sustainable development. In this agenda it is expressed the need for monitoring the evolution of this type of development through the use of indicators. This paper presents a collection of experiences in Venezuela for the measurement of sustainable development through the use of indicators and also presents a methodological approach based on statistical techniques for obtaining a sustainable development indicator for this country

Medición de Indicadores de Desarrollo Sostenible en Venezuela : Propuesta Metodológica

During the last four decades it has been proposed sustainable development as a viable option for ensuring economic growth, social equity and environment preservation in order to meet human needs in the present and in the future. In 1992 the world's nations had adopted Agenda 21, a plan for the sustainable development. In this agenda it is expressed the need for monitoring the evolution of this type of development through the use of indicators. This paper presents a collection of experiences in Venezuela for the measurement of sustainable development through the use of indicators and also presents a methodological approach based on statistical techniques for obtaining a sustainable development indicator for this country.En las últimas cuatro décadas se ha propuesto al desarrollo sostenible como la opción viable que asegura crecimiento económico, equidad social y preservación del medio ambiente para satisfacer las necesidades del hombre en el presente y en el futuro. En 1992 las naciones del mundo adoptaron la Agenda 21, un plan a favor del desarrollo sostenible. En dicha agenda se expresa la necesidad de monitorear la evolución de este tipo de desarrollo a través del uso de indicadores. En este trabajo se presenta una recopilación de experiencias en Venezuela en la medición del desarrollo sostenible a través del uso de indicadores, y se presentan una propuesta metodológica basada en técnicas estadísticas para la obtención de un indicador de desarrollo sostenible para este país