1,166 research outputs found
Estudio comparativo sobre el absentismo escolar entre el CEIP La Salud y el colegio Luther King Arafo.
El absentismo escolar es uno de los problemas más grandes de los que nos
encontramos en los centros educativos. Sin embargo, no se le da la importancia que
verdaderamente merece.
Este trabajo consiste en una investigación en la cual podremos observar un estudio
comparativo entre el absentismo en un centro escolar privado y uno público. A su vez,
trataremos el concepto de absentismo escolar y los motivos por los que se dan, la situación
en Canarias sobre el mismo.
A pesar de encontrarnos con diferentes definiciones sobre el “absentismo
escolar”, hemos considerado que la más completa es la de Uruñuela, donde nos dice que
este puede dividirse en varias fases.
Para llevar a cabo nuestra investigación hemos realizado un cuestionario a los
profesores de los centros mencionados, en los cuales coinciden nuestras ideas previas con
los resultados finales de los formularios.Truancy is one of the biggest problems we face in schools. However, it is not
given the importance it truly deserves.
This work consists of an investigation in which we can observe a comparative
study between absenteeism in a private school and a public school. In turn, we will discuss
the concept of school absenteeism and the reasons for it, the situation in the Canary
Islands about it.
Despite finding different definitions of "truancy", we have considered that the
most complete is the one of Uruñuela; it tells us that it can be divided into several phases.
Trabajo de Fin de Grado
To carry out our research we have made a questionnaire to the teachers of the mentioned
centers, in which they coincide our previous ideas with the final results of the forms
Attentional biases toward emotional images in the different episodes of bipolar disorder: An eye-tracking study.
Attentional biases toward emotional information may represent vulnerability and maintenance factors in bipolar disorder (BD). The present experimental study examined the processing of emotional information in BD patients using the eyetracking technology. Bipolar patients in their different states (euthymia, mania, depression) simultaneously viewed four pictures with different emotional valence (happy, neutral, sad, threatening for 20 s while their eye movements were monitored. A group of healthy individuals served as the control. The data revealed the following: (i) a decrease in attention to happy images in BD patients in their depressive episodes compared to healthy individuals, and (ii) an increase in attention to threatening images in BD patients (regardless of their episode) relative to the healthy controls. These biases appeared in the late stages of information processing and were sustained over the 20 s interval. Thus, the present findings reveal that attentional biases toward emotional information can be a key feature of BD, in that:(i) an anhedonic lack of sensitivity to positive stimuli during the bipolar depressive episode may be considered a maintaining factor of this clinical state, and (ii) the trait-bias toward threat, even in asymptomatic patients, may reflect a marker of vulnerability in BD
Estado de conservación de la ictiofauna arrecifal en sitios de buceo turístico de cuatro regiones del Archipiélago Sabana-Camagüey, Cuba.
Los peces constituyen uno de los atractivos principales en los arrecifes coralinos para el buceo
turístico, por lo cual resulta necesario monitorear su abundancia y valores estéticos. El objetivo de esta
investigación fue evaluar el estado de conservación de las asociaciones de peces arrecifales en cuatro de
los principales polos turísticos del Archipiélago Sabana-Camagüey, Cuba en el año 2010. Se
muestrearon 23 sitios de buceo turísticos en áreas adyacentes a las regiones de Varadero (5 sitios),
cayos de Villa Clara (6 sitios), Cayo Coco (6 sitios) y Santa Lucia (6 sitios). En cada uno de ellos se
realizaron seis réplicas de censos visuales de todas las especies de peces en recorridos lineales de 50 m
de largo por 2 m de ancho, ocupando un área total de 600 m2. El puntaje más alto de conservación lo
presentó los cayos de Villa Clara (37), siguiéndole en orden decreciente Cayo Coco (35), y con valores
más bajos Varadero (24) y Santa Lucia (22). Los puntajes de las cuatro regiones fueron inferiores a los
encontrados en otros arrecifes de Cuba y el Caribe. Los valores de Varadero y Santa Lucia se
correspondieron con los de arrecifes de hábitats degradados y sometidos a explotación pesquera. En
general, en la mayoría de las regiones predominaron peces de talla pequeña (<20 cm) pertenecientes a
las familias Pomacentridae y Labridae y hubo poca abundancia de peces carnívoros y herbívoros de
mediana (20-40 cm) y gran talla (>40 cm).
ABSTRACT
Fish are one of the main attractions on coral reefs for diving tourism; therefore, it is necessary to
monitor their condition and aesthetic values. The objective of this research was to evaluate the status of
reef fish assemblages in four tourist areas of Sabana-Camaguey Archipelago, Cuba in 2010. Twentythree
tourist diving sites were sampled in adjacent areas to regions of Varadero (five sites), Villa Clara
keys (6 sites), Coco key (6 sites) and Santa Lucia (6 sites). In each region, six replicated visual census of
all fish species were conducted along belt transects of 50 m length and 2 m width, occupying a total area
of 600 m2. The highest conservation score was obtained by Villa Clara keys (37), followed in decreasing
order by Coco key (35), and with lower values Varadero (24) and St. Lucia (22). The scores of the four
regions were lower than the values of other Cuban and Caribbean reefs. The values of Varadero and
Santa Lucia corresponded to reefs with degraded habitats and subject to overfishing. In general, small fish
(< 20 cm) from families Pomacentridae and Labridae, and low abundance of carnivore and herbivore fish
of middle (20-40 cm) and large size (> 40 cm) predominated in most regions
OTELO survey: optimal emission-line flux determination with OSIRIS/GTC
Emission-line galaxies are important targets for understanding the chemical
evolution of galaxies in the universe. Deep, narrow-band imaging surveys allow
to detect and study the flux and the equivalent widths (EW) of the emission
line studied. The present work has been developed within the context of the
OTELO project, an emission line survey using the Tunable Filters (TF) of
OSIRIS, the first generation instrument on the GTC 10.4m telescope located in
La Palma, Spain, that will observe through selected atmospheric windows
relatively free of sky emission lines. With a total survey area of 0.1 square
degrees distributed in different fields, reaching a 5 \sigma depth of 10^-18
erg/cm^2/s and detecting objects of EW < 0.3 A, OTELO will be the deepest
emission line survey to date. As part of the OTELO preparatory activities, the
objective of this study is to determine the best combination of sampling and
full width at half maximum (FWHM) for the OSIRIS tunable filters for deblending
H\alpha from [NII] lines by analyzing the flux errors obtained. We simulated
the OTELO data by convolving a complete set of synthetic HII galaxies in EW
with different widths of the OSIRIS TFs. We estimated relative flux errors of
the recovered H\alpha and [NII]6583 lines. We found that, for the red TF, a
FWHM of 12 A and a sampling of 5 A is an optimal combination that allow
deblending H\alpha from the [NII]6583 line with a flux error lower than 20%.
This combination will allow estimating SFRs and metallicities using the H\alpha
flux and the N2 method, respectively.Comment: 16 pages, 9 figures. Some authors added. Accepted for publication in
PAS
A fundamental plane for field star-forming galaxies
Star formation rate (SFR), metallicity and stellar mass are within the
important parameters of star--forming galaxies that characterize their
formation and evolution. They are known to be related to each other at low and
high redshift in the mass--metallicity, mass--SFR, and metallicity--SFR
relations. In this work we demonstrate the existence of a plane in the 3D space
defined by the axes SFR [log(SFR)(M_sun yr^-1)], gas metallicity [12+log(O/H)],
and stellar mass [log(M_star/M_sun)] of star-forming galaxies. We used
star--forming galaxies from the "main galaxy sample" of the Sloan Digital Sky
Survey--Data Release 7 (SDSS-DR7) in the redshift range 0.04 < z < 0.1 and
r-magnitudes between 14.5 and 17.77. Metallicities, SFRs, and stellar masses
were taken from the Max-Planck-Institute for Astrophysics-John Hopkins
University (MPA-JHU) emission line analysis database. From a final sample of
44214 galaxies, we find for the first time a fundamental plane for field
galaxies relating the SFR, gas metallicity, and stellar mass for star--forming
galaxies in the local universe. One of the applications of this plane would be
estimating stellar masses from SFR and metallicity. High redshift data from the
literature at redshift ~2.2 and 3.5, do not show evidence for evolution in this
fundamental plane.Comment: Accepted for publication in A&A. 4 pages, 4 Figures, and 2 online
figure
An Investigation of Radiation Heat Transfer in a Light-Duty Diesel Engine
In the last two decades engine research has been mainly focused on reducing pollutant emissions. This fact together with growing awareness about the impacts of climate change are leading to an increase in the importance of thermal efficiency over other criteria in the design of internal combustion engines (ICE). In this framework, the heat transfer to the combustion chamber walls can be considered as one of the main sources of indicated efficiency diminution. In particular, in modern direct-injection diesel engines, the radiation emission from soot particles can constitute a significant component of the efficiency losses. Thus, the main of objective of the current research was to evaluate the amount of energy lost to soot radiation relative to the input fuel chemical energy during the combustion event under several representative engine loads and speeds. Moreover, the current research characterized the impact of different engine operating conditions on radiation heat transfer. For this purpose, a combination of theoretical and experimental tools were used. In particular, soot radiation was quantified with a sensor that uses two-color thermometry along with its corresponding simplified radiation model. Experiments were conducted using a 4-cylinder direct-injection light-duty diesel engine fully instrumented with thermocouples. The goal was to calculate the energy balance of the input fuel chemical energy. Results provide a characterization of radiation heat transfer for different engine loads and speeds as well as radiation trends for different engine operating conditions.Benajes Calvo, JV.; Martín Díaz, J.; García Martínez, A.; Villalta Lara, D.; Warey, A.; Doménech Llopis, V.; Vassallo, AL.... (2015). An Investigation of Radiation Heat Transfer in a Light-Duty Diesel Engine. SAE International Journal of Engines. 8(5):1-14. doi:10.4271/2015-24-2443S1148
Larger in the disc of isolated active spiral galaxies than in their non-active twins
We present a comparison of the spin parameter , measured in a
region dominated by the galaxy disc, between 20 pairs of nearby
(0.005z0.03) seemingly isolated twin galaxies differing in nuclear
activity. We find that 80--82% of the active galaxies show higher values of
than their corresponding non-active twin(s), indicating larger
rotational support in the AGN discs. This result is driven by the 11 pairs of
unbarred galaxies, for which 100% of the AGN show larger than their
twins. These results can be explained by a more efficient angular momentum
transfer from the inflowing gas to the disc baryonic matter in the case of the
active galaxies. This gas inflow could have been induced by disc or bar
instabilities, although we cannot rule out minor mergers if these are prevalent
in our active galaxies. This result represents the first evidence of
galaxy-scale differences between the dynamics of active and non-active isolated
spiral galaxies of intermediate stellar masses (10
M) in the Local Universe.Comment: 11 pages, 7 figures. Accepted for publication in A&A Letter
Towards a new classification of galaxies: principal component analysis of CALIFA circular velocity curves
We present a galaxy classification system for 238 (E1-Sdm) CALIFA (Calar Alto
Legacy Integral Field Area) galaxies based on the shapes and amplitudes of
their circular velocity curves (CVCs). We infer the CVCs from the de-projected
surface brightness of the galaxies, after scaling by a constant mass-to-light
ratio based on stellar dynamics - solving axisymmetric Jeans equations via
fitting the second velocity moment of
the stellar kinematics. We use principal component analysis (PCA) applied to
the CVC shapes to find characteristic features and use a -means classifier
to separate circular curves into classes. This objective classification method
identifies four different classes, which we name slow-rising (SR), flat (FL),
round-peaked (RP) and sharp-peaked (SP) circular curves.
SR are typical for low-mass, late-type (Sb-Sdm), young, faint, metal-poor and
disc-dominated galaxies. SP are typical for high-mass, early-type (E1-E7), old,
bright, metal-rich and bulge-dominated galaxies. FL and RP appear presented by
galaxies with intermediate mass, age, luminosity, metallicity, bulge-to-disk
ratio and morphologies (E4-S0a, Sa-Sbc). The discrepancy mass factor,
, have the largest value for SR and SP classes ( 74
per cent and 71 per cent, respectively) in contrast to the FL and RP
classes (with 59 per cent and 61 per cent, respectively).
Circular curve classification presents an alternative to typical morphological
classification and appears more tightly linked to galaxy evolution.Comment: Accepted for publication in MNRAS (Minor changes), 123 pages, 19
figures, 87 Tables (containing the basic properties of the 238 E1-Sdm
galaxies; the five main Principal Component Eigenvectors; the five main
Principal Components - PC_i; the Multi-Gaussian Expansion models - MGEs; the
circular velocity curve models and their uncertainties
Evolution of the Fundamental Plane of 0.2<z<1.2 Early-type galaxies in the EGS
The Fundamental Plane relates the structural properties of early-type
galaxies such as its surface brightness and effective radius with its dynamics.
The study of its evolution has therefore important implications for models of
galaxy formation and evolution. This work aims to identify signs of evolution
of early-type galaxies through the study of parameter correlations using a
sample of 135 field galaxies extracted from the Extended Groth Strip in the
redshift range 0.2<z<1.2. Using DEEP2 data, we calculate the internal velocity
dispersions by extracting the stellar kinematics from absorption line spectra,
using a maximum penalized likelihood approach. Morphology was determined
through visual classification using the V+I images of ACS. The structural
parameters of these galaxies were obtained by fitting de Vaucouleurs stellar
profiles to the ACS I-band images, using the GALFIT code. S\'ersic and
bulge-to-disc decomposition models were also fitted to our sample of galaxies,
and we found a good agreement in the Fundamental Plane derived from the three
models. Assuming that effective radii and velocity dispersions do not evolve
with redshift, we have found a brightening of 0.68 mag in the B-band and 0.52
mag in the g-band at =0.7. However, the scatter in the FP is reduced by half
when we allow the FP slope to evolve, suggesting a different evolution of
early-type galaxies according to their intrinsic properties. The study of the
Kormendy relation shows the existence of a population of very compact (Re<2
Kpc) and bright galaxies (-21.5>Mg>-22.5), of which there are only a small
fraction (0.4%) at z=0. The evolution of these compact objects is mainly caused
by an increase in size that could be explained by the action of dry minor
mergers, and this population is responsible for the evolution detected in the
Fundamental Plane.Comment: Accepted for publication in A&A. 12 pages, 10 Figures, and 1 online
tabl
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