A VLT study of metal-rich extragalactic H II regions. I. Observations and empirical abundances

We have obtained spectroscopic observations from 3600 Angstrom to 9200 Angstrom with FORS at the Very Large Telescope for approximately 70 H II regions located in the spiral galaxies NGC 1232, NGC 1365, NGC 2903, NGC 2997 and NGC 5236. These data are part of a project aiming at measuring the chemical abundances and characterizing the massive stellar content of metal-rich extragalactic H II regions. In this paper we describe our dataset, and present emission line fluxes for the whole sample. In 32 H II regions we measure at least one of the following auroral lines: [S II]4072, [N II]5755, [S III]6312 and [O II]7325. From these we derive electron temperatures, as well as oxygen, nitrogen and sulphur abundances, using classical empirical methods (both so-called "Te-based methods" and "strong line methods"). Under the assumption that the temperature gradient does not introduce severe biases, we find that the most metal-rich nebulae with detected auroral lines are found at 12+log(O/H)~8.9, i.e. about 60% larger than the adopted solar value. However, classical abundance determinations in metal-rich H II regions may be severely biased and must be tested with realistic photoionization models. The spectroscopic observations presented in this paper will serve as a homogeneous and high-quality database for such purpose.Comment: Accepted for publication in Astronomy and Astrophysic

Diseño e implementación de un plan de mejoras para disminuir las devoluciones de productos de una fábrica de alimentos

El diseño e implementación de mejoras destinadas a la disminución de las devoluciones por parte de los clientes parte de un diagnóstico y comprobación de hipótesis. En la parte del diagnóstico, se realizó un análisis histórico de los datos donde se encontró posibles causas del problema; productos que más se devuelven, clientes que más los devuelven y diferentes tipos de problemas a lo largo de la cadena logística como mal paletizado, temperaturas inadecuadas etc. Una vez concluido con el diagnóstico, se procedió al planteamiento de hipótesis del problema, que fueron comprobadas a través de la investigación. Luego de definir las variables que causaban las devoluciones se definieron, bajo el uso de un diagrama de árbol, las causas raíces del problema. Estas causas generaron el diseño de 17 mejoras destinadas para corregir los problemas encontrados, mejoras que modifican diferentes procesos tanto operativos como administrativos y plantean diferentes tipos de control que buscan la disminución de todo tipo de devoluciones. Las mejoras fueron implementadas durante el mes de Octubre del 2003 y posteriormente evaluadas para medir el alcance de los objetivos y el ahorro efectivo obtenido

Lo cotidiano en la vivienda popular de Quito

Access to housing is a problem that concern especially in Latin America, the deficit is not only quantitative, it also includes qualitative aspects, and the presence of informality in housing is increasing, this shows that housing programs should be concerned more for poor or less favored sectors, sectors that cannot access a home, and in the case that they obtain it, they do not cover the needs of their users. The house must be conceived as a complex whole that has multiple simultaneous dynamics according to the relationships of the individuals inside and outside, considering that individuals by nature must appropriate or personalize their space, to satisfy their needs, and the imposition of architectural models is an obstacle that must be overcome. In recent decades there have been paradigm changes that include new criteria, new philosophical thinking, the society is conceived as more diverse and less hierarchical, persons in the future are reconsidered within the criteria of sustainability. In this context, housing design cannot respond only to economic, political, technological, and aesthetic aspects; leaving aside the social aspects; the intention of this article is to make a methodological proposal that denotes the needs of individuals and reflects the particularities of the current reality.Al tratar el tema de la vivienda, una de las problemáticas de mayor preocupación en Latinoamérica es el déficit no solo cuantitativo, sino también cualitativo. Uno de los rasgos más evidentes es el aumento constante de la informalidad de la vivienda, esto evidencia que los programas de vivienda deben preocuparse más por sectores pobres o menos favorecidos, que no pueden acceder a una vivienda, y en el caso que la obtengan no cubren las necesidades de sus usuarios. La vivienda debe ser concebida como un todo complejo que tiene múltiples dinámicas simultáneas de acuerdo con las relaciones de los individuos en su interior y exterior, considerando que los individuos por naturaleza tienden a apropiarse o personalizar su espacio, para satisfacer sus necesidades. De esta manera, la imposición de modelos arquitectónicos es un obstáculo que se debe superar, teniendo en cuenta que en las últimas décadas se han producido cambios de paradigma que incluyen nuevos criterios y nuevos pensamientos; esto significa que a la sociedad se la concibe más diversa y menos jerárquica, se replantea el bienestar de los individuos a futuro dentro de los criterios de sostenibilidad. Dentro de este contexto, el diseño de la vivienda no puede responder únicamente a los aspectos económicos, políticos, tecnológicos y estéticos, dejando de lado los aspectos sociales. Por tanto, la intención de este artículo es plantear una propuesta metodológica que denote las necesidades de los individuos y refleje las particularidades de la realidad actual

Genetic variability and structure of an isolated population of Ambystoma altamirani, a mole salamander that lives in the mountains of one of the largest urban areas in the world

Amphibians are globally threatened by habitat loss and fragmentation; species within the order Ambystoma are not the exception, as there are 18 species of mole salamanders in México, of which 16 are endemic and all species are under some national or international status of protection. The mole salamander, Ambystoma altamirani is a microendemic species, which is distributed in central México, within the trans-Mexican volcanic belt, and is one of the most threatened species due to habitat destruction and the introduction of exotic species. Nine microsatellite markers were used to determine the genetic structure, genetic variability, effective population size, presence of bottlenecks and inbreeding coefficient of one population of A. altamirani to generate information which might help to protect and conserve this threatened species. We found two genetic subpopulations with significant level of genetic structure (FST = 0.005) and high levels of genetic variability (Ho = 0.883; He = 0.621); we also found a small population size (Ne = 8.8), the presence of historical (M = 0.486) and recent bottlenecks under IAM and TPM models, with a low, but significant coefficient of inbreeding (FIS = −0.451). This information will help us to raise conservation strategies of this microendemic mole salamander species

Stellar Population in LLAGN.I: Ground-based observations

(Abridge): We present a spectroscopic study of the stellar populations of Low Luminosity AGN (LLAGN). Our main goal is to determine whether the stars who live in the innermost (100 pc-scale) regions of these galaxies are in some way related to the emission line properties, which would imply a link between the stellar population and the ionization mechanism. High signal to noise, ground based long-slit spectra in the 3500--5500 A interval were collected for 60 galaxies.Our main findings are: (1) Few LLAGN have a detectable young (< 10 Myr) starburst component, indicating that very massive stars do not contribute significantly to the optical continuum. In particular, no features due to Wolf-Rayet stars were convincingly detected. (2) High Order Balmer absorption lines of HI (HOBLs), on the other hand, are detected in 40% of LLAGN. These features, which are strongest in 100 Myr--1 Gyr intermediate age stellar populations, are accompanied by diluted metal absorption lines and bluer colors than other objects in the sample. (3) These intermediate age populations are very common (50 %) in LLAGN with relatively weak [OI] emission, but rare (10 %) in LLAGN with stronger [OI]. This is intriguing since LLAGN with weak [OI] have been previously hypothesized to be ``transition objects'' in which both an AGN and young stars contribute to the emission-line excitation. Massive stars, if present, are completely outshone by intermediate age and old stars in the optical. This happens in at least a couple of objects where independent UV spectroscopy detects young starbursts not seen in the optical. (4) Objects with predominantly old stars span the whole range of [OI]/Halpha values, but (5) sources with significant young and/or intermediate age populations are nearly all (90%) weak [OI] emitters.Comment: To be published in ApJ (April issue). Paper with full resolution images is at: http://www.iaa.csic.es/~rosa/preprints/preprints.html http://www.journals.uchicago.edu/ApJ/journa

Starburst99: Synthesis Models for Galaxies with Active Star Formation

Starburst99 is a comprehensive set of model predictions for spectrophotometric and related properties of galaxies with active star formation. The models are an improved and extended version of the data set previously published by Leitherer & Heckman (1995). We have upgraded our code by implementing the latest set of stellar evolution models of the Geneva group and the model atmosphere grid compiled by Lejeune et al. (1997). Several predictions which were not included in the previous publication are shown here for the first time. The models are presented in a homogeneous way for five metallicities between Z = 0.040 and 0.001 and three choices of the initial mass function. The age coverage is 10^6 to 10^9 yr. We also show the spectral energy distributions which are used to compute colors and other quantities. The full data set is available for retrieval at http://www.stsci.edu/science/starburst99/. This website allows users to run specific models with non-standard parameters as well. We also make the source code available to the community.Comment: 32 pages, LaTeX. All the Figures and the summary Table are located at http://www.stsci.edu/science/starburst99/, ApJ accepte