1,509 research outputs found
Exploring the Concept of the Digital Educator During COVID-19
T In many machine learning classification problems, datasets are usually of high dimensionality and therefore require efficient and effective methods for identifying the relative importance of their attributes, eliminating the redundant and irrelevant ones. Due to the huge size of the search space of the possible solutions, the attribute subset evaluation feature selection methods are not very suitable, so in these scenarios feature ranking methods are used. Most of the feature ranking methods described in the literature are univariate methods, which do not detect interactions between factors. In this paper, we propose two new multivariate feature ranking methods based on pairwise correlation and pairwise consistency, which have been applied for cancer gene expression and genotype-tissue expression classification tasks using public datasets. We statistically proved that the proposed methods outperform the state-of-the-art feature ranking methods Clustering Variation, Chi Squared, Correlation, Information Gain, ReliefF and Significance, as well as other feature selection methods for attribute subset evaluation based on correlation and consistency with the multi-objective evolutionary search strategy, and with the embedded feature selection methods C4.5 and LASSO. The proposed methods have been implemented on the WEKA platform for public use, making all the results reported in this paper repeatable and replicabl
Imprints of galaxy evolution on H ii regions Memory of the past uncovered by the CALIFA survey
H ii regions in galaxies are the sites of star formation and thus particular
places to understand the build-up of stellar mass in the universe. The line
ratios of this ionized gas are frequently used to characterize the ionization
conditions. We use the Hii regions catalogue from the CALIFA survey (~5000 H ii
regions), to explore their distribution across the classical [OIII]/Hbeta vs.
[NII]/Halpha diagnostic diagram, and how it depends on the oxygen abundance,
ionization parameter, electron density, and dust attenuation. We compared the
line ratios with predictions from photoionization models. Finally, we explore
the dependences on the properties of the host galaxies, the location within
those galaxies and the properties of the underlying stellar population. We
found that the location within the BPT diagrams is not totally predicted by
photoionization models. Indeed, it depends on the properties of the host
galaxies, their galactocentric distances and the properties of the underlying
stellar population. These results indicate that although H ii regions are short
lived events, they are affected by the total underlying stellar population. One
may say that H ii regions keep a memory of the stellar evolution and chemical
enrichment that have left an imprint on the both the ionizing stellar
population and the ionized gasComment: 18 pages, 8 figures, accepted for publishing in A&
The Mass-Metallicity relation explored with CALIFA: I. Is there a dependence on the star formation rate?
We present the results on the study of the global and local M-Z relation
based on the first data available from the CALIFA survey (150 galaxies). This
survey provides integral field spectroscopy of the complete optical extent of
each galaxy (up to 2-3 effective radii), with enough resolution to separate
individual HII regions and/or aggregations. Nearly 3000 individual HII
regions have been detected. The spectra cover the wavelength range between
[OII]3727 and [SII]6731, with a sufficient signal-to-noise to derive the oxygen
abundance and star-formation rate associated with each region. In addition, we
have computed the integrated and spatially resolved stellar masses (and surface
densities), based on SDSS photometric data. We explore the relations between
the stellar mass, oxygen abundance and star-formation rate using this dataset.
We derive a tight relation between the integrated stellar mass and the
gas-phase abundance, with a dispersion smaller than the one already reported in
the literature (0.07 dex). Indeed, this
dispersion is only slightly larger than the typical error derived for our
oxygen abundances. However, we do not find any secondary relation with the
star-formation rate, other than the one induced due to the primary relation of
this quantity with the stellar mass. We confirm the result using the 3000
individual HII regions, for the corresponding local relations.
Our results agree with the scenario in which gas recycling in galaxies, both
locally and globally, is much faster than other typical timescales, like that
of gas accretion by inflow and/or metal loss due to outflows. In essence,
late-type/disk dominated galaxies seem to be in a quasi-steady situation, with
a behavior similar to the one expected from an instantaneous
recycling/closed-box model.Comment: 19 Pages, 8 figures, Accepted for Publishing in Astronomy and
Astrophysics (A&A
Potential Impact of Mediterranean Aquaculture on the Wild Predatory Bluefish
Aquaculture impacts on wild populations of fish have been considered principally due to farm escapes. The Bluefish Pomatomus saltatrix, which exhibits two distinct genetic units in the Mediterranean Sea, is a voracious predator and is attracted to aquaculture cages to prey on farmed fish, particularly Gilthead Seabream Sparus aurata and European Sea Bass Dicentrarchus labrax. We compared the genetic diversity of adult Bluefish caught inside one aquaculture farm located in Spanish waters of the western Mediterranean Sea with reference individuals of East and West Mediterranean stocks from the open sea. Bluefish were genetically assigned to their putative origin using seven microsatellite loci and mitochondrial cytochrome oxidase subunit I as molecular markers. As expected, most of the individuals caught from inside the fish farm cages were assigned to the local genetic population. However, between 7.14% and 11.9% of individuals were assigned to the distant and different genetic unit inhabiting Turkish waters, the East Mediterranean stock. The genetic membership of those individuals revealed some degree of interbreeding between the East and West Mediterranean Bluefish stocks. All results suggest that aquaculture acts as an attractor for Bluefish and could affect genetic diversity as well as phylogeography of this fish and maybe other similar species that aggregate around marine fish farms.We are very grateful to T. Ceyhan for providing the Bluefish samples from Turkey. The study was supported by the MICINN CGL-2009-08279 Grant (Spain) and the Asturian Grant GRUPIN2014-093. Laura Miralles held a PCTI Grant from the Asturias Regional Government, referenced BP 10-004. This is a contribution from the Marine Observatory of Asturias
Dense gas in IRAS 20343+4129: an ultracompact HII region caught in the act of creating a cavity
The intermediate- to high-mass star-forming region IRAS 20343+4129 is an
excellent laboratory to study the influence of high- and intermediate-mass
young stellar objects on nearby starless dense cores, and investigate for
possible implications in the clustered star formation process. We present 3 mm
observations of continuum and rotational transitions of several molecular
species (C2H, c-C3H2, N2H+, NH2D) obtained with the Combined Array for Research
in Millimetre-wave Astronomy, as well as 1.3 cm continuum and NH3 observations
carried out with the Very Large Array, to reveal the properties of the dense
gas. We confirm undoubtedly previous claims of an expanding cavity created by
an ultracompact HII region associated with a young B2 zero-age main sequence
(ZAMS) star. The dense gas surrounding the cavity is distributed in a filament
that seems squeezed in between the cavity and a collimated outflow associated
with an intermediate-mass protostar. We have identified 5 millimeter continuum
condensations in the filament. All of them show column densities consistent
with potentially being the birthplace of intermediate- to high-mass objects.
These cores appear different from those observed in low-mass clustered
environments in sereval observational aspects (kinematics, temperature,
chemical gradients), indicating a strong influence of the most massive and
evolved members of the protocluster. We suggest a possible scenario in which
the B2 ZAMS star driving the cavity has compressed the surrounding gas,
perturbed its properties and induced the star formation in its immediate
surroundings.Comment: 17 pages, 13 figures. Accepted for publication in Monthly Notices of
the Royal Astronomical Society (Main Journal
Extreme Starbursts in the Local Universe
The "Extreme starbursts in the local universe" workshop was held at the
Insituto de Astrofisica de Andalucia in Granada, Spain on 21-25 June 2010.
Bearing in mind the advent of a new generation of facilities such as JWST,
Herschel, ALMA, eVLA and eMerlin, the aim of the workshop was to bring together
observers and theorists to review the latest results. The purpose of the
workshop was to address the following issues: what are the main modes of
triggering extreme starbursts in the local Universe? How efficiently are stars
formed in extreme starbursts? What are the star formation histories of local
starburst galaxies? How well do the theoretical simulations model the
observations? What can we learn about starbursts in the distant Universe
through studies of their local counterparts? How important is the role of
extreme starbursts in the hierarchical assembly of galaxies? How are extreme
starbursts related to the triggering of AGN in the nuclei of galaxies? Overall,
41 talks and 4 posters with their corresponding 10 minutes short talks were
presented during the workshop. In addition, the workshop was designed with
emphasis on discussions, and therefore, there were 6 discussion sessions of up
to one hour during the workshop. Here is presented a summary of the purposes of
the workshop as well as a compilation of the abstracts corresponding to each of
the presentations. The summary and conclusions of the workshop along with a
description of the future prospects by Sylvain Veilleux can be found in the
last section of this document. A photo of the assistants is included.Comment: worksho
Effect of tapentadol on neurons in the locus coeruleus
Tapentadol is a novel centrally acting drug that combines mu-opioid receptor (MOR) agonism and
noradrenaline reuptake inhibition (NRI), producing analgesic effects in various painful conditions. We
investigated the acute effects of tapentadol in the locus coeruleus (LC), a central nucleus regulated by the
noradrenergic and opioid systems that is critical in pain modulation. In single-unit extracellular recordings
of LC neurons from anaesthetized male SpragueeDawley rats, tapentadol clearly inhibited the
spontaneous electrophysiological activity of LC neurons in a dose-dependent manner (ED50 Âź 0.8 mg/kg).
This inhibitory effect was reversed by RX821002 (an alpha2-adrenoceptor antagonist) and naloxone (a
mu-opioid receptor antagonist) by 96.7% and 28.2%, respectively. Pretreatment with RX821002, Nethoxycarbonyl-
2-ethoxy-1-2-dihydroquinoline (EEDQ, an irreversible alpha2-adrenoceptor antagonist)
or naloxone shifted the tapentadol doseeeffect curve to the right (ED50 Âź 2.2 mg/kg, 2.0 mg/kg and
2.1 mg/kg, respectively). Furthermore, tapentadol inhibited the LC response to mechanical stimulation of
the hindpaw in a dose-dependent manner. In summary, we demonstrate that acute administration of
tapentadol inhibits LC neurons in vivo, mainly due to the activation of alpha2-adrenoceptors. These data
suggest that both the noradrenergic and opioid systems participate in the inhibitory effect of tapentadol
on LC neurons, albeit to different extents, which may account for its potent analgesic effect and mild
opioidergic side-effects.This study was supported by grants from GrĂźnenthal GmbH
(OT2010/075); âFondo de InvestigaciĂłn Sanitariaâ (PI10/01221 and
PI12/00915); CIBERSAM (G18); Junta de AndalucĂa, ConsejerĂa de
InnovaciĂłn, Ciencia y Empresa (CTS-510, CTS-4303 and CTS-7748);
CĂĄtedra Externa del Dolor GrĂźnenthal-Universidad de CĂĄdiz;
FP7-PEOPLE-2010-RG (268377); FPU (AP2007-02397) and FPI
(2011-145) fellowship
The problematic use of Information and Communication Technologies (ICT) in adolescents by the cross sectional JOITIC study
Background: The emerging field of Information and Communications Technology (ICT) has brought about new interaction styles. Its excessive use may lead to addictive behaviours. The objective is to determine the prevalence of the problematic use of ICT such as Internet, mobile phones and video games, among adolescents enrolled in mandatory Secondary Education (ESO in Spanish) and to examine associated factors. Methods: Cross sectional, multi-centric descriptive study. Population: 5538 students enrolled in years one to four of ESO at 28 schools in the Vallès Occidental region (Barcelona, Spain). Data collection: self-administered socio-demographic and ICT access questionnaire, and validated questionnaires on experiences related to the use of the Internet, mobile phones and video games (CERI, CERM, CERV). Results: Questionnaires were collected from 5,538 adolescents between the ages of 12 and 20 (77.3 % of the total response), 48.6 % were females. Problematic use of the Internet was observed in 13.6 % of the surveyed individuals; problematic use of mobile phones in 2.4 % and problematic use in video games in 6.2 %. Problematic Internet use was associated with female students, tobacco consumption, a background of binge drinking, the use of cannabis or other drugs, poor academic performance, poor family relationships and an intensive use of the computer. Factors associated with the problematic use of mobile phones were the consumption of other drugs and an intensive use of these devices. Frequent problems with video game use have been associated with male students, the consumption of other drugs, poor academic performance, poor family relationships and an intensive use of these games. Conclusions: This study offers information on the prevalence of addictive behaviours of the Internet, mobile phones and video game use. The problematic use of these ICT devices has been related to the consumption of drugs, poor academic performance and poor family relationships. This intensive use may constitute a risk marker for ICT addictio
Single hadron response measurement and calorimeter jet energy scale uncertainty with the ATLAS detector at the LHC
The uncertainty on the calorimeter energy response to jets of particles is
derived for the ATLAS experiment at the Large Hadron Collider (LHC). First, the
calorimeter response to single isolated charged hadrons is measured and
compared to the Monte Carlo simulation using proton-proton collisions at
centre-of-mass energies of sqrt(s) = 900 GeV and 7 TeV collected during 2009
and 2010. Then, using the decay of K_s and Lambda particles, the calorimeter
response to specific types of particles (positively and negatively charged
pions, protons, and anti-protons) is measured and compared to the Monte Carlo
predictions. Finally, the jet energy scale uncertainty is determined by
propagating the response uncertainty for single charged and neutral particles
to jets. The response uncertainty is 2-5% for central isolated hadrons and 1-3%
for the final calorimeter jet energy scale.Comment: 24 pages plus author list (36 pages total), 23 figures, 1 table,
submitted to European Physical Journal
Standalone vertex ďŹnding in the ATLAS muon spectrometer
A dedicated reconstruction algorithm to find decay vertices in the ATLAS muon spectrometer is presented. The algorithm searches the region just upstream of or inside the muon spectrometer volume for multi-particle vertices that originate from the decay of particles with long decay paths. The performance of the algorithm is evaluated using both a sample of simulated Higgs boson events, in which the Higgs boson decays to long-lived neutral particles that in turn decay to bbar b final states, and pp collision data at âs = 7 TeV collected with the ATLAS detector at the LHC during 2011
- âŚ