786 research outputs found
Análisis cinemático del viraje en el esquí alpino de competición
Esta comunicación trata sobre la aplicación de la Biomecánica Deportiva como perspectiva
científica, al análisis cinemático del esquí alpino como objeto de estudio, y ha sido realizada
basándose en una situación real de competición como fue el Campeonato del Mundo de 1996
celebrado en Sierra Nevada (Granada). Para el análisis de la muestra, utilizamos la metodología
y las tecnologías propias de la biomecánica Deportiva como son el método indirecto y las técnicas
fotogramétricas tridimensionales, basadas en la filmación del gesto deportivo utilizando el vídeo.
Los resultados obtenidos muestran la existencia de un patrón general de movimiento en la
muestra de esquiadoras analizadas en cuanto a las velocidades tangenciales medias del CG(S).del
sistema (esquiador más implementos). Entre las conclusiones, destacamos la existencia de una
reducción de la velocidad tangencial media resultante en el recorrido analizado que es mayor aún,
en el instante de paso del palo de viraje en particular y cuanto más curva es la trayectoria. Atendiendo
a la desviación típica del comportamiento de la velocidad media resultante, podemos decir
que en este tramo de paso de la puerta encontramos las diferencias entre la técnica individual de
las esquiadoras analizadas.
Este estudio nos confirma la importancia del entrenamiento en situación real de competición
(en cuanto a material, características pista de entrenamiento, etc.
Aplicación de hielo incluyendo conservantes naturales para la mejora de la calidad de especies marinas refrigeradas
6 páginas, 4 figurasComo resultado de la creciente demanda de productos marinos frescos de alta calidad, la tecnología de alimentos ha desarrollado una gran diversidad de estrategias novedosas de refrigeración que han contribuido al desarrollo continuado y a la innovación en el sector. En este trabajo se describe la actividad llevada a cabo en los últimos años en nuestro grupo de trabajo. En él, se desarrolló una estrategia nueva consistente en emplear como medio de refrigeración hielo preparado a partir de disoluciones acuosas incluyendo componentes conservantes naturales de distinta procedencia (extractos vegetales, ácidos orgánicos de pequeño tamaño y extractos de macroalgas)Los experimentos fueron financiados por la Secretaría Xeral de I+D de la Xunta de Galicia (Galicia, España) (Proyecto 10 TAL 018E), el Consejo Superior de Investigaciones Científicas (CSIC; Proyecto PIE 201370E001) y el Programa de Cooperación Hispano-Chileno “Universidad de Chile-Consejo Superior de Investigaciones Científicas (CSIC) (Proyecto 2004 CL 0038).Peer reviewe
Detection of rat brain activation using statistical parametric mapping analysis in FDG-PET studies
[Abstract] AMI International Conference 2003, September 21 - 27, Madrid, Spain: High Resolution Molecular Imaging: from Basic Science to Clinical ApplicationsStatistical parametric mapping (SPM) is an analysis technique long been used in clinical research to detect subtle activity changes in brain; it is an excellent exploratory tool as it does not require a priori assumptions about the expected brain region activations.
Research in animal imaging may also take benefit from this technique, if properly adapted to the new scenario. This is the case of brain activation studies in murine models using PET tracers and dedicated imaging devices. This work proposes the use of an SPM methodology adapted to the analysis of 2-deoxy-2-[18F] fluoro-D-Glucose (FDG) positron emission tomography (PET) scans of rat brains. Advantages over conventional region of interest (ROI) based analysis were assessed in an experiment addressing the detection of brain activation in of rats which underwent three different visual stimulation paradigmsPublicad
The ALHAMBRA survey: Accurate merger fractions by PDF analysis of photometric close pairs
Our goal is to develop and test a novel methodology to compute accurate close
pair fractions with photometric redshifts. We improve the current methodologies
to estimate the merger fraction f_m from photometric redshifts by (i) using the
full probability distribution functions (PDFs) of the sources in redshift
space, (ii) including the variation in the luminosity of the sources with z in
both the selection of the samples and in the luminosity ratio constrain, and
(iii) splitting individual PDFs into red and blue spectral templates to deal
robustly with colour selections. We test the performance of our new methodology
with the PDFs provided by the ALHAMBRA photometric survey. The merger fractions
and rates from the ALHAMBRA survey are in excellent agreement with those from
spectroscopic work, both for the general population and for red and blue
galaxies. With the merger rate of bright (M_B <= -20 - 1.1z) galaxies evolving
as (1+z)^n, the power-law index n is larger for blue galaxies (n = 2.7 +- 0.5)
than for red galaxies (n = 1.3 +- 0.4), confirming previous results.
Integrating the merger rate over cosmic time, we find that the average number
of mergers per galaxy since z = 1 is N_m = 0.57 +- 0.05 for red galaxies and
N_m = 0.26 +- 0.02 for blue galaxies. Our new methodology exploits
statistically all the available information provided by photometric redshift
codes and provides accurate measurements of the merger fraction by close pairs
only using photometric redshifts. Current and future photometric surveys will
benefit of this new methodology.Comment: Submitted to A&A, 15 pages, 15 figures, 6 tables. Comments are
welcome. Close pair systems available at
https://cloud.iaa.csic.es/alhambra/catalogues/ClosePairs
The ALHAMBRA survey: evolution of galaxy spectral segregation
We study the clustering of galaxies as a function of spectral type and
redshift in the range using data from the Advanced Large
Homogeneous Area Medium Band Redshift Astronomical (ALHAMBRA) survey. The data
cover 2.381 deg in 7 fields, after applying a detailed angular selection
mask, with accurate photometric redshifts [] down to
. From this catalog we draw five fixed number density,
redshift-limited bins. We estimate the clustering evolution for two different
spectral populations selected using the ALHAMBRA-based photometric templates:
quiescent and star-forming galaxies. For each sample, we measure the real-space
clustering using the projected correlation function. Our calculations are
performed over the range Mpc, allowing us to find a
steeper trend for Mpc, which is especially clear for
star-forming galaxies. Our analysis also shows a clear early differentiation in
the clustering properties of both populations: star-forming galaxies show
weaker clustering with evolution in the correlation length over the analysed
redshift range, while quiescent galaxies show stronger clustering already at
high redshifts, and no appreciable evolution. We also perform the bias
calculation where similar segregation is found, but now it is among the
quiescent galaxies where a growing evolution with redshift is clearer. These
findings clearly corroborate the well known colour-density relation, confirming
that quiescent galaxies are mainly located in dark matter halos that are more
massive than those typically populated by star-forming galaxies.Comment: 14 pages, 9 figures, accepted by Ap
The ALHAMBRA survey : Estimation of the clustering signal encoded in the cosmic variance
The relative cosmic variance () is a fundamental source of
uncertainty in pencil-beam surveys and, as a particular case of count-in-cell
statistics, can be used to estimate the bias between galaxies and their
underlying dark-matter distribution. Our goal is to test the significance of
the clustering information encoded in the measured in the ALHAMBRA
survey. We measure the cosmic variance of several galaxy populations selected
with band luminosity at as the intrinsic dispersion in
the number density distribution derived from the 48 ALHAMBRA subfields. We
compare the observational with the cosmic variance of the dark
matter expected from the theory, . This provides an
estimation of the galaxy bias . The galaxy bias from the cosmic variance is
in excellent agreement with the bias estimated by two-point correlation
function analysis in ALHAMBRA. This holds for different redshift bins, for red
and blue subsamples, and for several band luminosity selections. We find
that increases with the band luminosity and the redshift, as expected
from previous work. Moreover, red galaxies have a larger bias than blue
galaxies, with a relative bias of . Our results
demonstrate that the cosmic variance measured in ALHAMBRA is due to the
clustering of galaxies and can be used to characterise the affecting
pencil-beam surveys. In addition, it can also be used to estimate the galaxy
bias from a method independent of correlation functions.Comment: Astronomy and Astrophysics, in press. 9 pages, 4 figures, 3 table
Emploi de glace portant des acides organiques naturels pendant l’entreposage de poisson à bord
Presentación de la conferencia dictada en el Colloque QSPA, Qualité et Sécurité des Produits Aquatiques, Boulogne (France), 18 juin 2015Peer reviewe
GRB 050904 at redshift 6.3: observations of the oldest cosmic explosion after the Big Bang
We present optical and near-infrared observations of the afterglow of the
gamma-ray burst GRB 050904. We derive a photometric redshift z = 6.3, estimated
from the presence of the Lyman break falling between the I and J filters. This
is by far the most distant GRB known to date. Its isotropic-equivalent energy
is 3.4x10^53 erg in the rest-frame 110-1100 keV energy band. Despite the high
redshift, both the prompt and the afterglow emission are not peculiar with
respect to other GRBs. We find a break in the J-band light curve at t_b = 2.6
+- 1.0 d (observer frame). If we assume this is the jet break, we derive a
beaming-corrected energy E_gamma = (4-12)x10^51 erg. This limit shows that GRB
050904 is consistent with the Amati and Ghirlanda relations. This detection is
consistent with the expected number of GRBs at z > 6 and shows that GRBs are a
powerful tool to study the star formation history up to very high redshift.Comment: 3 figures, 5 pages, accepted for publication in A&A Letters. One
figure added, minor modifications. Full author list in the pape
The alhambra survey: evolution of galaxy spectral segregation
We study the clustering of galaxies as a function of spectral type and redshift in the range 0.35 <z <1.1 using data from the Advanced Large Homogeneous Area Medium Band Redshift Astronomical (ALHAMBRA) survey. The data cover 2.381 deg2 in 7 fields, after applying a detailed angular selection mask, with accurate photometric redshifts down to IAB <24. From this catalog we draw five fixed number density redshift-limited bins. We estimate the clustering evolution for two different spectral populations selected using the ALHAMBRA-based photometric templates: quiescent and star-forming galaxies. For each sample we measure the real-space clustering using the projected correlation function. Our calculations are performed over the range [0.03, 10.0] h-1 Mpc, allowing us to find a steeper trend for Mpc, which is especially clear for star-forming galaxies. Our analysis also shows a clear early differentiation in the clustering properties of both populations: star-forming galaxies show weaker clustering with evolution in the correlation length over the analyzed redshift range, while quiescent galaxies show stronger clustering already at high redshifts and no appreciable evolution. We also perform the bias calculation where similar segregation is found, but now it is among the quiescent galaxies where a growing evolution with redshift is clearer (abrigatted). These findings clearly corroborate the well-known color-density relation, confirming that quiescent galaxies are mainly located in dark matter halos that are more massive than those typically populated by star-forming galaxies.Ministerio de Economía y Competitividad y FEDER AYA2010-22111-C03-02 AYA2013-48623-C2-2 AYA2012-39620 AYA2013-40611-P AYA2013-42227-P AYA2013-43188-P AYA2013-48623-C2-1 ESP2013-48274 AYA2014-58861-C3-1Junta de Andalucía TIC114 JA2828 P10-FQM-644
The ALHAMBRA survey : band luminosity function of quiescent and star-forming galaxies at by PDF analysis
Our goal is to study the evolution of the band luminosity function (LF)
since using ALHAMBRA data. We used the photometric redshift and the
band selection magnitude probability distribution functions (PDFs) of those
ALHAMBRA galaxies with mag to compute the posterior LF. We
statistically studied quiescent and star-forming galaxies using the template
information encoded in the PDFs. The LF covariance matrix in
redshift-magnitude-galaxy type space was computed, including the cosmic
variance. That was estimated from the intrinsic dispersion of the LF
measurements in the 48 ALHAMBRA sub-fields. The uncertainty due to the
photometric redshift prior is also included in our analysis. We modelled the LF
with a redshift-dependent Schechter function affected by the same selection
effects than the data. The measured ALHAMBRA LF at and the
evolving Schechter parameters both for quiescent and star-forming galaxies
agree with previous results in the literature. The estimated redshift evolution
of is and , and of is
and . The measured faint-end slopes are and . We find a significant
population of faint quiescent galaxies, modelled by a second Schechter function
with slope . We find a factor decrease in the
luminosity density of star-forming galaxies, and a factor
increase in the of quiescent ones since , confirming the continuous
build-up of the quiescent population with cosmic time. The contribution of the
faint quiescent population to increases from 3% at to 6% at .
The developed methodology will be applied to future multi-filter surveys such
as J-PAS.Comment: Accepted for publication in Astronomy and Astrophysics. 25 pages, 20
figures, 7 table
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