3,663 research outputs found
Model-Driven Technologies for Data Mining Democratisation
Data mining techniques allow discovering insights previously hidden in data from a domain. However, these techniques demand very specialised skills. People often lack these skills, which hinders data mining
democratisation. To alleviate this situation, we defined a model-driven framework and some domain-specific languages that contribute to the democratisation of data mining. Here we summarise these contributions
TBT e imposex en Galicia: los efectos de un disruptor endocrino en poblaciones de gasterópodos marinos
En este artículo se resume la experiencia de nuestro grupo de investigación en el campo de los efectos de un disruptor endocrino
androgenizante (el tributilo de estaño, más conocido como TBT por su abreviatura del inglés tributyltin) en gasterópodos marinos del
litoral gallego. Nuestras investigaciones sobre este tema comenzaron en 1996 y continúan en la actualidad. Después de una breve
introducción sobre qué es el TBT y su problemática, se resumen los principales hallazgos conseguidos con nuestro trabajo, que se
basan principalmente en el estudio de los efectos en el gasterópodo carnívoro Nucella lapillus con alguna información adicional para
otras especies como el carroñero Nassarius reticulatus. Nuestro trabajo abarca tanto la bioacumulación de contaminante, la
manifestación de un biomarcador específico de los efectos del TBT (masculinización de hembras, conocido como imposex) en
poblaciones naturales y en experiencias de trasplante, el estudio de la presencia de individuos genéticamente más resistentes a los
efectos del TBT y algunos datos de ecología molecular sobre la estructuración poblacional y capacidad de dispersión de Nucella lapillus
Spatial, temporal and quantitative assessment of catalyst leaching in continuous flow
Catalyst leaching is a major impediment to the development of commercially-viable processes conducted in a liquid-phase. To date, there is no reliable technique that can accurately identify the extent and dynamics of the leaching process in a quantitative manner. In this work, a tandem flow-reactor system has been developed, which allowed us to distinguish between surface-catalyzed reactions from those occurring in solution by comparing%conversion at the exit of each reactor (S1, S2) corresponding to predominance of heterogeneous/homogeneous reactions (spatial) and two different residence times (temporal). A multiscale model is subsequently established to quantify the two types of reaction rate and simulate the catalyst leaching from a cross-coupling catalyst, PdEncat™ 30; including: (1) a multi-particle sizes model for catalyst scale; and (2) a dispersion model for reactor scale. The results show that catalyst leaching occurs via more than one process, and that the homogeneous Pd-catalyst (leached from the immobilized catalyst and dissolved in the flow) dominates the reaction and possesses a much higher activity than the heterogeneous (immobilized) Pd-catalyst. Additionally, the change of leached Pd stream inside reactors can be predicted along with the axial direction and the reaction time through the reactor-scale dispersion model
On the Detection of CMB B-modes from Ground at Low Frequency
The primordial CMB -mode search is on the spotlight of the scientific
community due to the large amount of cosmological information that is encoded
in the primeval signal. However, the detection of this signal is challenging
from the data analysis point of view, due to the relative low amplitude
compared to the foregrounds, the lensing contamination coming from the leakage
of -modes, and the instrumental noise. Here, we studied the viability of the
detection of the primordial polarization -mode with a ground-based telescope
operating in the microwave low-frequency regime (i.e., from 10GHz-120GHz) in a
handful of different scenarios: i. the instrument's channels distribution and
noise, ii. the tensor-to-scalar ratio () detectability considering different
possible values and degrees of delensing, iii. the effect of including a
possible source of polarized anomalous microwave emission (AME), iv. the
strengths and weaknesses of different observational strategies and, v. the
atmospheric and systematic noise impact on the recovery. We focused mainly on
the removal of galactic foregrounds as well as noise contamination by applying
a full-parametric pixel-based maximum likelihood component separation
technique. Moreover, we developed a numerical methodology to estimate the
residuals power spectrum left after component separation, which allow us to
mitigate possible biases introduced in the primordial -mode power spectrum
reconstruction. Among many other results, we found that this sort of experiment
is capable of detecting Starobinsky's even when no delensing is performed
or, a possible polarized AME contribution is taken into account. Besides, we
showed that this experiment is a powerful complement to other on-ground or
satellite missions, such as LiteBIRD, since it can help significantly with the
low-frequency foregrounds characterization.Comment: 28 pages, 18 figures, submitted to JCA
Restructuring of supported Pd by green solvents: an operando Quick EXAFS (QEXAFS) study and implications for the derivation of structure-function relationships in Pd catalysis
Transmission electron microscopy (TEM) is commonly used as an ex-situ technique to determine structural changes by comparing images of catalyst particles before and after a reaction. This requires the use of an alcoholic solvent to disperse the particles on a grid. In this work, we will show that Pd catalysts can be transformed during the procedure, by using EXAFS to determine the structure of Pd catalysts in different environments (as dry or wet samples). Supported palladium nanoparticles exposed to aqueous ethanolic solution (50% w/v) are transformed to a common, reduced, and hydrogen-contaminated state, irrespective of their initial habit or support. Catalysts comprised of nanosize PdO are reduced at ca. 350 K, whereas samples comprised of very small (ca. ≤ 10 atoms) Pd particles react with the solvent at just above room temperature and agglomerating with considerable loss of dispersion. As such any potential benefits to catalysis sought through the synthesis of very highly dispersed metallic Pd supported upon a range of inorganic dispersants will be rapidly erased through the action of such solvents
Cosmological Scaling Solutions with Tachyon:Modified Gravity Model
Modifying the Einstein's gravity at large distance scales is one of the
interesting proposals to explain the late time acceleration of the universe. In
this paper, we analyse scaling solutions in modified gravity models where the
universe is sourced by a background matter fluid together with a tachyon type
scalar field. We describe a general prescription to calculate the scaling
potential in such models. Later on, we consider specific examples of
modifications and apply our method to calculate the scaling potential and the
scale factor. Our method can be applied to any modified gravity model, in
presence of a tachyon field.Comment: 6 pages, latex style, modified version, two new figures included, new
refernces added, Accepted for publication in Physics Letters
Quintessence and Scalar Dark Matter in the Universe
Continuing with previous works, we present a cosmological model in which dark
matter and dark energy are modeled by scalar fields and ,
respectively, endowed with the scalar potentials and . This model contains 95% of
scalar field. We obtain that the scalar dark matter mass is The solution obtained allows us to recover the success of the
standard CDM. The implications on the formation of structure are reviewed. We
obtain that the minimal cutoff radio for this model is Comment: 4 pages REVTeX, 3 eps color figures. Minor changes and references
updated. To appear in Classical and Quantum Gravity as a Letter to the
Editor. More information at http://www.fis.cinvestav.mx/~siddh/PHI
Applications of scalar attractor solutions to Cosmology
We develop a framework to study the phase space of a system consisting of a
scalar field rolling down an arbitrary potential with varying slope and a
background fluid, in a cosmological setting. We give analytical approximate
solutions of the field evolution and discuss applications of its features to
the issues of quintessence, moduli stabilisation and quintessential inflation.Comment: 9 pages, 7 figures. Accepted for publication in PR
Long-Distance Transport of Finisher Pigs in the Iberian Peninsula:Effects of Season on Thermal and Enthalpy Conditions, Welfare Indicators and Meat pH
Long-distance transport in the global swine industry is more the rule than the
exception. We tested the impact on the rates of temperature change and air enthalpy on the stress
response and muscle pH in pigs subjected to long-distance travel from Spain to Portugal performed in the summer and winter. We found that winter journeys are more adverse for the animals because during the journey, abrupt variations in rates of temperature change and air enthalpy caused a marked physiological stress response and effects on the meat pH after 45 min. These results indicate the need to develop new environmental control strategies that mitigate abrupt temperature changes during travel to attenuate the biological cost of such long-distance transport on the animals
Scalar Field as Dark Matter in the Universe
We investigate the hypothesis that the scalar field is the dark matter and
the dark energy in the Cosmos, wich comprises about 95% of the matter of the
Universe. We show that this hypothesis explains quite well the recent
observations on type Ia supernovae.Comment: 4 pages REVTeX, 1 eps figure. Minor changes. To appear in Classical
and Quantum Gravit
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