270 research outputs found
Radio Observations of a galactic high energy gamma-ray source
No full textPSR B1706-44 is one of the very few galactic pulsars that has been discovered at TeV energies. PSR B1706-44 has been also detected in the Xray domain. It has been suggested that the high energy radiation could be due to inverse Compton radiation from a pulsar wind nebula (PWN).We report on VLA high-resolution observations of a region around the pulsar PSR B1706-44 at 1.4, 4.8 and 8.4 GHz. The pulsar appears embedded in a synchrotron nebula. We propose that this synchrotron nebula is the radio counterpart of the high energy emission powered by the spin-down energy of the pulsar.Fil: Giacani, Elsa Beatriz. Consejo Nacional de Investigaciónes Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Astronomía y Física del Espacio. - Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Astronomía y Física del Espacio; ArgentinaFil: Rovero, Adrian Carlos. Consejo Nacional de Investigaciónes Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Astronomía y Física del Espacio. - Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Astronomía y Física del Espacio; Argentin
STRUCTURE-ACTIVITY RELATIONSHIP STUDIES AND CONFORMATIONAL ANALYSIS OF NOVEL ANTIRETROVIRAL PEPTIDES DERIVED FROM FELINE IMMUNODEFICIENCY VIRUS GLYCOPROTEIN GP36.
No full textOn the redshift of the gamma-ray blazar PKS 0447-439: Optical spectroscopy using Gemini observations with high S/N ratio
No full textAbstract: The BL-Lac blazar PKS 0447-439 was detected at very high energy gamma-rays by HESS following the discovery by Fermi-LAT. The lack of both emission and absorption lines in BL-Lacs make the estimation of their redshifts very difficult. Modeling the drop in gamma-ray spectra it was possible to have an estimation of redshift for PKS 0447-439 of z approx 0.2, which is compatible with the value z=0.205 reported by the identification of Ca II absorption lines in optical spectra. By the identification of a weak line of Mg II using spectra with average signal-to-noise S/N approx 80, it has been recently reported a lower limit for the redshift of this blazar of z<=1.246. Triggered by this controversy, we have proposed new optical observations with the Gemini South telescope to perform further spectroscopic analysis with very high S/N ratio (approx 200-500). In this work we present a new optical spectrum of PKS 0447-439, and report on the analysis and results of such observations. Even with this significantly high quality signal we were not able to identify any spectral features to allow an estimation of the redshift. In agreement with other recent studies, we identify the Mg II line reported previously as originated in the Earth´s atmosphere, and conclude the lower limit of the redshift is incorrect. More interestingly, we could not identify the Ca II absorption lines used to report a redshift of 0.205.Fil: Donzelli, Carlos. Universidad Nacional de Córdoba. Observatorio Astronómico de Córdoba; Argentina.Fil: Donzelli, Carlos. Conicet. Instituto de Astronomía Teórica y Experimental; Argentina.Fil: Muriel, Hernán. Universidad Nacional de Córdoba. Observatorio Astronómico de Córdoba; Argentina.Fil: Muriel, Hernán. Conicet. Instituto de Astronomía Teórica y Experimental; Argentina.http://adsabs.harvard.edu/abs/2013arXiv1307.6907RAstronomía (incluye Astrofísica y Ciencias del Espacio
Primates decline rapidly in unprotected forests: Evidence from a monitoring program with data constraints
No full textCopyright: © 2015 Rovero et al. This is an open
access article distributed under the terms of the
Creative Commons Attribution License, which permits
unrestricted use, distribution, and reproduction in any
medium, provided the original author and source are
credited.Growing threats to primates in tropical forests make robust and long-term population abundance
assessments increasingly important for conservation. Concomitantly, monitoring becomes
particularly relevant in countries with primate habitat. Yet monitoring schemes in
these countries often suffer from logistic constraints and/or poor rigor in data collection, and
a lack of consideration of sources of bias in analysis. To address the need for feasible monitoring
schemes and flexible analytical tools for robust trend estimates, we analyzed data
collected by local technicians on abundance of three species of arboreal monkey in the
Udzungwa Mountains of Tanzania (two Colobus species and one Cercopithecus), an area
of international importance for primate endemism and conservation. We counted primate
social groups along eight line transects in two forest blocks in the area, one protected and
one unprotected, over a span of 11 years. We applied a recently proposed open metapopulation
model to estimate abundance trends while controlling for confounding effects of observer,
site, and season. Primate populations were stable in the protected forest, while the
colobines, including the endemic Udzungwa red colobus, declined severely in the unprotected
forest. Targeted hunting pressure at this second site is the most plausible explanation
for the trend observed. The unexplained variability in detection probability among
transects was greater than the variability due to observers, indicating consistency in data
collection among observers. There were no significant differences in both primate abundance
and detectability between wet and dry seasons, supporting the choice of sampling
during the dry season only based on minimizing practical constraints. Results show that
simple monitoring routines implemented by trained local technicians can effectively detect
changes in primate populations in tropical countries. The hierarchical Bayesian model formulation
adopted provides a flexible tool to determine temporal trends with full account for
any imbalance in the data set and for imperfect detection
Primates decline rapidly in unprotected forests: Evidence from a monitoring program with data constraints
No full textCopyright: © 2015 Rovero et al. This is an open
access article distributed under the terms of the
Creative Commons Attribution License, which permits
unrestricted use, distribution, and reproduction in any
medium, provided the original author and source are
credited.Growing threats to primates in tropical forests make robust and long-term population abundance
assessments increasingly important for conservation. Concomitantly, monitoring becomes
particularly relevant in countries with primate habitat. Yet monitoring schemes in
these countries often suffer from logistic constraints and/or poor rigor in data collection, and
a lack of consideration of sources of bias in analysis. To address the need for feasible monitoring
schemes and flexible analytical tools for robust trend estimates, we analyzed data
collected by local technicians on abundance of three species of arboreal monkey in the
Udzungwa Mountains of Tanzania (two Colobus species and one Cercopithecus), an area
of international importance for primate endemism and conservation. We counted primate
social groups along eight line transects in two forest blocks in the area, one protected and
one unprotected, over a span of 11 years. We applied a recently proposed open metapopulation
model to estimate abundance trends while controlling for confounding effects of observer,
site, and season. Primate populations were stable in the protected forest, while the
colobines, including the endemic Udzungwa red colobus, declined severely in the unprotected
forest. Targeted hunting pressure at this second site is the most plausible explanation
for the trend observed. The unexplained variability in detection probability among
transects was greater than the variability due to observers, indicating consistency in data
collection among observers. There were no significant differences in both primate abundance
and detectability between wet and dry seasons, supporting the choice of sampling
during the dry season only based on minimizing practical constraints. Results show that
simple monitoring routines implemented by trained local technicians can effectively detect
changes in primate populations in tropical countries. The hierarchical Bayesian model formulation
adopted provides a flexible tool to determine temporal trends with full account for
any imbalance in the data set and for imperfect detection
Imaginar la gerencia universitaria a través de metaforas
No full textMetaphors are a path used today by some organizations in the education sector, aimed at understanding the dynamics of their processes and making proposals for action aimed to achieve the fulfillment of management practices. Metaphors will allow a global vision of the organizations, not from a linear perspective, focused on cause - effect relationship but as a comprehensive and interconnected view of the whole to their parts and the parts to the whole. The university management is the framework of action of the purposes of the Venezuelan universities, which essentially represent the functions of: teaching, research and extension. To conceive that management through metaphors is the fundamental purpose of this article. To achieve this purpose, the documentary bibliographic research design was employed, taking into consideration the documentary analysis for its development. Also as tool and technique for collecting information, the textual signing of the summary type was employed, and finally it was considered the underlining technique. The author Gareth Morgan (1990) who provides in his book "Images of the organization" a methodology for organizational analysis is shown as the theoretical driving thread. The final considerations revolved around imagining the university management from the point of view of metaphors, as a new vision in the practice of managers in college education organizations.Las metáforas constituyen una senda empleada hoy en día por algunas organizaciones del sector educativo cuyo objetivo es comprender la dinámica de sus procesos y hacer propuestas de acción encaminadas lograr la efectividad de las prácticas gerenciales. Las metáforas van a permitir tener una visión global de la organización, no desde un punto de vista lineal, enfocada a causa –efecto sino una visión integral e interrelacionada del todo con sus partes y las partes con el todo. La gerencia universitaria constituye el marco de acción de los propósitos de las universidades venezolanas, en cuya esencia están representados las funciones de: Docencia, investigación y extensión. Poder visualizar esa gerencia a través de las metáforas es el propósito fundamental de este artículo. Para su desarrollo se acudió empleo la investigación tipo bibliográfico de diseño documental, tomando en consideración el análisis documental. Asimismo se aplicó como instrumentos y técnicas de recolección de información el fichaje tipo resumen, el bibliográfico y el textual, finalmente se consideró la técnica del subrayado. Como hilo conductor teórico se muestra al autor Gareth Morgan (1990) en su libro “Imágenes de la organización”, quien brinda una metodología para el análisis organizacional. Las consideraciones finales giraron en torno a imaginar a la gerencia universitaria desde el punto de vista de las metáforas, como una nueva visión en la praxis de los gerentes de las organizaciones de educación universitaria
Brain Volume of the Newly-Discovered Species Rhynchocyon udzungwensis (Mammalia: Afrotheria: Macroscelidea): Implications for Encephalization in Sengis
No full textabstract: The Gray-faced Sengi (Rhynchocyon udzungwensis) is a newly-discovered species of sengi (elephant-shrew) and is the largest known extant representative of the order Macroscelidea. The discovery of R. udzungwensis provides an opportunity to investigate the scaling relationship between brain size and body size within Macroscelidea, and to compare this allometry among insectivorous species of Afrotheria and other eutherian insectivores. We performed a spin-echo magnetic resonance imaging (MRI) scan on a preserved adult specimen of R. udzungwensis using a 7-Tesla high-field MR imaging system. The brain was manually segmented and its volume was compiled into a dataset containing previously-published allometric data on 56 other species of insectivore-grade mammals including representatives of Afrotheria, Soricomorpha and Erinaceomorpha. Results of log-linear regression indicate that R. udzungwensis exhibits a brain size that is consistent with the allometric trend described by other members of its order. Inter-specific comparisons indicate that macroscelideans as a group have relatively large brains when compared with similarly-sized terrestrial mammals that also share a similar diet. This high degree of encephalization within sengis remains robust whether sengis are compared with closely-related insectivorous afrotheres, or with more-distantly-related insectivorous laurasiatheres.This article is published at http://journals.plos.org/plosone/article?id=10.1371/journal.pone.005866
Statistical redshift of the very-high-energy blazar S5 0716+714
No full textContext. Blazars are the most numerous class of very-high-energy (VHE; E > 100 GeV) gamma-ray emitters. At present, measured redshifts are available only for about 80% of the VHE gamma-ray sources; this is mainly due to the difficulty in measuring reliable redshifts from their nearly featureless continuum optical spectra.
Aims. As the VHE sky is still vastly unexplored, VHE blazars are unique objects. High-energy spectra from blazars are used for extragalactic background light studies, to investigate topics related to cosmology or fundamental physics, and to find the source luminosity. This allows one to study the properties of the host galaxy, its black hole, and the gamma-ray emission mechanisms. All of these studies require suitable estimations of the blazar distance, which has motivated the use of novel approaches when measuring the redshift of faint optical lines in their spectra is very uncertain.
Methods. We present the new optical spectroscopic observations of S5 0716+714 and its environment taken on December 20, 2019, with the Gemini GMOS North telescope.
Results. We do not find any absorption lines in the blazar spectrum; however, we were able to get the redshifts of 21 other galaxies in the field, 15 of which form a group at z = 0.2304 ± 0.0013. Performing a population study of galaxies, we found that S5 0716+714 belongs to this group with a probability > 99%
Overcoming the Populist Discourse: A Literary Analysis of the Methodology in Patria o muerte
No full textThe centrality of Simón Bolívar in the Venezuelan imaginarium has contemporarily been replaced by Hugo Chávez Frías (1999 - 2013). To the point that Chávez has centralized not just the government, but also the lives of Venezuelans around his own. Even after his death, the effects of his charisma, his connection with the group that he had identified as “the people”, still affect Venezuelans. Although Maduro, another protagonist in the Chavista era, is in power, the analysis of the cultural legacy left by Chávez is of great importance, not just historically but socially, for Venezuelans. The interpretation of the Bolivarian legacy is a still developing field, however, the need to interpret and understand this phenomenon has created a new effort in various academic fields. Examples could be: How sociology has focused on studying the aesthetic and stylistic choices in Chávez’s discourse (Frajman 2014; Castro 2013); how the political sciences has made an effort to understand the political theory behind Chavismo (Ramos Jiménez 2011; Martínez Meucci 2014); Meanwhile historians have been focusing on the changes that the regime has tried to bring about in the Venezuelan imaginarium (Kozak Rovero 2013, 2015; Langue 2013; Quintero 2018). The literary field has also produced various interesting interpretations, such as the novel analysed by this thesis, Patria o muerte by Venezuelan author Alberto Barrera Tyszka, which, although award-winning, has not been the subject of rigorous analysis. The objective of this thesis is to fill that emptiness, in a concrete manner. Firstly, it will bring out the formal aspects of the piece that have not been detailed in the few studies and commentaries given to the piece. More specifically, it will demonstrate that the narrative in Patria o muerte responds to a very effective strategic plan that confers to the novel a complexity not yet appreciated. Secondly, it will demonstrate that this narrative plan reveals a fundamental connection with some of the key concepts developed in the social sciences, in particular the concept of ‘charisma’ according to Lindholm (2013), ‘neopopulism’ according to Ramos Jiménez (2011), and the ‘guerra de memorias’ (‘memory wars’) according to Langue (2013). Furthermore, it will argue that the hybridity of genres in the novel and its intricate playfulness with perspectives are able to counter the binary divisions promoted by the neopopulist chavista discourse and its opposition; through the demystification of Chávez figure and the emphasis given to the voices of the minority outside of the binary system of pro-Chávez and anti-Chávez, the novel then projects a dynamic and complex image of the chavista legacy
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