Study of star-forming galaxies in SDSS up to redshift 0.4: I. Metallicity evolution

The chemical composition of the gas in galaxies versus cosmic time provides a very important tool for understanding galaxy evolution. Although there are many studies at high redshift, they are rather scarce at lower redshifts. However, low redshift studies can provide important clues about the evolution of galaxies, furnishing the required link between local and high redshift universe. In this work we focus on the metallicity of the gas of star-forming galaxies at low redshift, looking for signs of chemical evolution. To analyze the metallicity contents star-forming galaxies of similar luminosities and masses at different redshifts. With this purpose, we present a study of the metallicity of relatively massive (log(M_star/M_sun)>10.5) star forming galaxies from SDSS--DR5 (Sloan Digital Sky Survey--Data Release 5), using different redshift intervals from 0.04 to 0.4. We used data processed with the STARLIGHT spectral synthesis code, correcting the fluxes for dust extinction, estimating metallicities using the R_23 method, and segregating the samples with respect to the value of the [NII]6583/[OII]3727 line ratio in order to break the R_23 degeneracy selecting the upper branch. We analyze the luminosity and mass-metallicity relations, and the effect of the Sloan fiber diameter looking for possible biases. By dividing our redshift samples in intervals of similar magnitude and comparing them, significant signs of metallicity evolution are found. Metallicity correlates inversely with redshift: from redshift 0 to 0.4 a decrement of ~0.1 dex in 12+log(O/H) is found.Comment: 11 pages, 9 figures, Accepted for publication in A&

A Heuristic-Based Simulation for an Education Process to Learn about Optimization Applications in Logistics and Transportation

In the context of the DigiLab4U international project, this paper describes a simulationbased serious game that can be used as a virtual teaching lab in higher education courses, especially in Industrial and Systems Engineering, Data Science, Management Science and Operations Research, as well as Computer Science. The learning activity focuses on understanding distribution logistics problems related to transportation optimization using different techniques. These optimization challenges include the vehicle routing problem, the arc routing problem, and the team orienteering problem. As a result of the learning process in the virtual lab, it is expected that students acquire competencies and skills related to logistics and transportation challenges as well as problem-solving. These competencies and skills can be precious for students’ future careers, since they increase students’ analytical skills, capacity to understand heuristic-based algorithms, teamwork and interdisciplinary communication skills, programming skills, and statistical abilities. A preliminary version of this training activity has already been used in MSc and PhD courses held at universities in Spain, Italy, Ireland, and Portugal

XMM-Newton and Deep Optical Observations of the OTELO fields: the Groth-Westphal Strip

OTELO (OSIRIS Tunable Emission Line Object Survey) will be carried out with the OSIRIS instrument at the 10 m GTC telescope at La Palma, and is aimed to be the deepest and richest survey of emission line objects to date. The deep narrow-band optical data from OSIRIS will be complemented by means of additional observations that include: (i) an exploratory broad-band survey that is already being carried out in the optical domain, (ii) FIR and sub-mm observations to be carried with the Herschel space telescope and the GTM, and (iii) deep X-Ray observations from XMM-Newton and Chandra.Here we present a preliminary analysis of public EPIC data of one of the OTELO targets,the Groth-Westphal strip, gathered from the XMM-Newton Science Archive (XSA). EPIC images are combined with optical BVRI data from our broadband survey carried out with the 4.2m WHT at La Palma. Distance-independent diagnostics (involving X/O ratio, hardness ratios, B/T ratio) are tested.Comment: 2 pages, 2 figures, uses graphicx package. To appear in proceedings of "The X-Ray Universe 2005", San Lorenzo del Escorial, Spain, September 26-30, 200

A scintillating plastic fiber tracking detector for neutron and proton imaging and spectroscopy

We report the results of recent calibration data analysis of a prototype scintillating fiber tracking detector system designed to perform imaging, spectroscopy and particle identification on 20 to 250 MeV neutrons and protons. We present the neutron imaging concept and briefly review the detection principle and the prototype description. The prototype detector system records ionization track data on an event-by-event basis allowing event selection criteria to be used in the off-line analysis. Images of acrylic phantoms from the analysis of recent proton beam calibrations (14 to 65 MeV range) are presented as demonstrations of the particle identification, imaging and energy measurement capabilities. The measured position resolution is c 500 pm. The measured energy resolution (AE/E, FWHM) is 14.2% at 35 MeV. An effective technique for track identification and data compression is presented. The detection techniques employed can be applied to measurements in a variety of disciplines including solar and atmospheric physics, radiation therapy and nuclear materials monitoring. These applications are discussed briefly as are alternative detector configurations and future development plans

English language proficiency, complete tooth loss, and recent dental visits among older adults in the United States

Objectives: This study sought to provide population-based estimates of complete tooth loss and recent dental visits among older adults in the United States by English language proficiency. Methods: We conducted a cross-sectional analysis of the 2017 Medical Expenditure Panel Survey among participants 50 years of age (n = 10,452, weighted to represent 111,895,290 persons). Five categories of language proficiency were created based on self-reported English language ability and language spoken at home (Spanish, Other). Results: The prevalence of complete tooth loss was higher among those with limited English proficiency (Spanish speaking: 13.7%; Other languages: 16.9%) than those proficient in English (Spanish speaking: 5.0%; Other languages: 6.0%, English only: 12.0%). Complete tooth loss was less common among participants for whom Spanish was their primary language, with limited English proficiency relative to English only (adjusted odds ratio: 0.56; 95% confidence interval: 0.42-0.76). Among those without complete tooth loss, dental visits in the past year were less common among participants with primary language other than English as compared to those who only speak English. Conclusions: Complete tooth loss varied by English language proficiency among adults aged 50 years in the United States. Suboptimal adherence to annual dental visits was common, more so in those with complete tooth loss, and varied by English language proficiency