1,725,468 research outputs found
Espectroscopia en el cúmulo abierto NGC 6834
Get PDFLos cúmulos abiertos son objetos ideales para estudiar estrellas masivas y de masa intermedia. En particular NGC 6834 es un objeto muy estudiado, sin embargo no hay muchas determinaciones de tipos espectrales de sus estrellas miembro. Con el fin de realizar una clasificación espectral y derivar los parámetros estelares fundamentales, hemos trabajado con espectros, adquiridos por el observatorio Gemini Norte, con el instrumento GMOS en modo máscara. Se determinaron los parámetros fundamentales de 36 estrellas observadas en la región de NGC 6834. Cabe destacar que para la mayoría de estas estrellas es la primera vez que se les determinó su clasificación espectral, temperatura efectiva, gravedad superficial y magnitudes absolutas visual y bolométrica.Open clusters are ideal objects for the study of massive and intermediate-mass stars. In particular NGC 6834 is a well-studied object, however there are not many spectral type determinations of its member stars. To perform a spectral classification and derive the fundamental stellar parameters, we have worked with spectra acquired by the Gemini North Observatory with the GMOS instrument in mask mode. The fundamental parameters of 36 stars observed in the region of NGC 6834 were determined. It is noteworthy that for most of these stars it is the first time that their spectral classification, effective temperature, surface gravity, and visual and bolometric absolute magnitudes have been determined.Instituto de Astrofísica de La Plat
Improvement of plant growth and seed yield in Jatropha curcas by a novel nitrogen-fixing root associated Enterobacter species
Get PDF10.1186/1754-6834-6-140Biotechnology for Biofuels61
Production of marker-free transgenic Jatropha curcas expressing hybrid Bacillus thuringiensis δ-endotoxin Cry1Ab/1Ac for resistance to larvae of tortrix moth (Archips micaceanus)
Get PDF10.1186/1754-6834-7-68Biotechnology for Biofuels716
Directed evolution of an E. coli inner membrane transporter for improved efflux of biofuel molecules
No full text10.1186/1754-6834-6-81Biotechnology for Biofuels618
Fotometría "Python" del cúmulo abierto NGC 6834
Get PDFLos cúmulos abiertos (CA) son objetos ideales para estudiar estrellas masivas y de masa intermedia. En particular NGC 6834 es un CA muy estudiado, pero sus parámetros fundamentales aún tienen una gran dispersión. Con el fin de estimar mejor dichos parámetros, hemos trabajado con imágenes del CA, adquiridas por el observatorio Gemini Norte, y procesadas con herramientas basadas en el lenguaje Python, tales como DRAGONS para la prerreducción y Photutils para extraer la fotometría. Se construyeron diagramas colorcolor y color-magnitud que permitieron adoptar una distancia de 3.33 ± 0.57 Kpc y estimar un exceso de color E(B — V) = 0.66 mag. Utilizando datos de IPHAS se identificaron 32 objetos que tendrían emisión en H∞, de los cuales 21 serían candidatas a Be.Open clusters are ideal objects for studying intermediate and massive stars. In particular, NGC 6834 is a well-studied cluster with fundamental parameters that currently present a large dispersion. In order to better estimate these parameters, we have worked with images of the cluster adquired at the Gemini North Observatory, and processed with tools based on the Python language, such as DRAGONS for pre-reduction and Photutils for photometry. We constructed color-color and color-magnitude diagrams that allowed us to adopt a distance of 3.33 ±0.57 kpc and to estimate a color excess E(B — V) = 0.66 mag. Using IPHAS data we identified 32 objects that would have emission of H∞ of which 21 would be Be star candidates.Asociación Argentina de Astronomí
Optical/IR studies of Be stars in NGC 6834 with emphasis on two specific stars
No full textWe present optical and infrared photometric and spectroscopic studies of two Be stars in the 70–80-Myr-old open cluster NGC 6834. NGC 6834(1) has been reported as a binary from speckle interferometric studies whereas NGC 6834(2) may possibly be a γ Cas-like variable. Infrared photometry and spectroscopy from the United Kingdom Infrared Telescope (UKIRT), and optical data from various facilities are combined with archival data to understand the nature of these candidates. High signal-to-noise near-IR spectra obtained from UKIRT have enabled us to study the optical depth effects in the hydrogen emission lines of these stars. We have explored the spectral classification scheme based on the intensity of emission lines in the H and K bands and contrasted it with the conventional classification based on the intensity of hydrogen and helium absorption lines. This work also presents hitherto unavailable UBV CCD photometry of NGC 6834, from which the evolutionary state of the Be stars is identified
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
- …
