505 research outputs found
Glacial refugia and mid-Holocene expansion delineate the current distribution of Castanea sativa in Europe
We thank J.A. LĂłpez-SaĂ©z for very useful comments that improved the quality of the manuscript. We also thank two anonymous reviewers for their useful suggestions. JVRD was supported by "Severo Ochoa" PhD Grant (BP 12-093) and by funding through "Ayuda para Estancias Breves" (EB15-12) for a research stay at Masaryk University (Brno, Czech Republic) in 2015. Both grants were provided by the "Plan de Ciencia, TecnologĂa e InnovaciĂłn" (PCTI) Government of Principado de Asturias. BJA was supported by the project Employment of Best Young Scientists for International Cooperation Empowerment (CZ.1.07/2.3.00/30.0037) co-financed from the European Social Fund and the state budget of the Czech Republic. MC was supported by the Czech Science Foundation (Centre of Excellence PLADIAS, 14-36079G).Areas of Quaternary refugia for tree species have been mainly delineated based on fossil records and phylogeography, but niche modelling can provide useful complementary information. Here we use palaeodistribution modelling to test the main hypotheses about the distribution of Castanea sativa in the Last Glacial Maximum (LGM) and the mid-Holocene in Europe. We computed distribution models for current climatic conditions using different methods, and projected them onto three climatic scenarios for the LGM and the mid-Holocene. The projections were validated with pollen and charcoal records. LGM refugia were suggested in the north of the Iberian, Italian and Balkan Peninsulas, and in northern Anatolia. The projections for the mid-Holocene indicated high climatic suitability and geographic expansion of the species range across southern Europe, including some areas where the species is nowadays considered as non-native. In general, our models are consistent with the patterns proposed with pollen and charcoal records, and partially also with phylogeographic information inferred from genetic data, suggesting that the most suitable areas for C. sativa were extended significantly during the mid-Holocene, but declined afterwards and lost connectivity. The projected patterns were compatible with existing palaeobotanical records of C. sativa and provide a spatially-explicit picture of the species past distribution
Studying the dosage-dependent influence of hydrophobic alkoxysilane/siloxane admixtures on the performance of repair micromortars
Cracks sealing in deteriorated concrete often requires the use of repair mortars of compatible composition, good adhesion to the substrate and free of shrinkage. Even where repair mortars properly bond to the substrate, that interface affords a preferred pathway for water ingress. Hydrophobic repair micromortars designed to seal cracks via injection might be one way to solve that problem. This article analyses the effect of adding three hydrophobic products (generic labelled as UCA-TP) comprising silica oligomers, n-octylamine (a surfactant) and polydimethylsiloxane (PDMS) in different proportions (10 wt% of PDMS :UCA-TP10, 28 wt% of PDMS: UCA-TP28 and 56 wt% of PDMS: UCA-TP56) to a fresh repair micromortar. The incorporation of UCA-TP products hastened the early hydration kinetics of repair micromortars, and, at the same time, after 7 days of hydration, declined the total heat released (the higher is the content of UCA-TP product and its proportion of PDMS the lower is the heat of hydration. The inclusion of the hydrophobic products substantially modified the repair micomortar wetting and water transport properties, by inducing a hydrophobic behavior (contact angle >100 degrees) and decreasing water absorption by >60%. Although adding those products to the repair micromortars increased porosity and lowered mechanical performance, 28 d compressive strength was consistently >50 MPa, a value that compared well to the original substrate. Simulated cracks were very effectively sealed by the repair micromortars
DiagnĂłstico de la Planta de LixiviaciĂłn de la oficina Salitrera Santa Laura en Chile. Patrimonio de la Humanidad
The Santa Laura Saltpeter Work, which is nowadays the place where the most complete industrial infrastructure of the nitrate processing period is maintained, has a Leaching Tower that is considered by its uniqueness, the icon of the former nitrate industry in Chile. This impressive structure, built mostly in Oregon Pine wood (Pseudotsuga menziesii) with metal junctions, unfortunately bears, after the plant stopped producing nitrate and iodine, the impact of its productive past and subsequent human actions because of neglect and lack of maintenance. This report, based on a visual, instrumental and structural inspection, is a diagnosis of the current condition of the building. The results indicate that the elements of the structure, with some exceptions, are in good condition and without changes in their mechanical properties. Structural analysis determined that the plant behavior is favorable, being able to withstand a seismic event of importance.La oficina salitrera Santa Laura, que es actualmente el lugar donde se mantiene la infraestructura industrial mĂĄs completa del periodo del procesamiento del salitre, posee una Torre de LixiviaciĂłn que es considerada, por su singularidad, el Ăcono de la otrora industria salitrera en Chile. Esta impresionante estructura, construida casi en su totalidad con madera de Pino OregĂłn (Pseudotsuga menziesii) y elementos metĂĄlicos en sus uniones, sobrelleva desafortunadamente, despuĂ©s del cese del proceso de fabricaciĂłn de salitre y yodo, el impacto de su pasado productivo y posteriores acciones antrĂłpicasambientales producto de su abandono y falta de mantenimiento. El presente informe, que contemplo inspecciĂłn bĂĄsica, instrumental y anĂĄlisis estructural, es un diagnĂłstico del estado actual de conservaciĂłn del edificio. Los resultados obtenidos indican que los elementos que conforman la estructura, con algunas excepciones, se encuentran en buen estado y sin alteraciĂłn de sus propiedades mecĂĄnicas. El anĂĄlisis estructural determinĂł que el comportamiento de la planta es favorable, siendo capaz de soportar un evento sĂsmico de importancia
Stellar populations of galaxies in the ALHAMBRA survey up to . I. MUFFIT: A Multi-Filter Fitting code for stellar population diagnostics
We present MUFFIT, a new generic code optimized to retrieve the main stellar
population parameters of galaxies in photometric multi-filter surveys, and we
check its reliability and feasibility with real galaxy data from the ALHAMBRA
survey. Making use of an error-weighted -test, we compare the
multi-filter fluxes of galaxies with the synthetic photometry of mixtures of
two single stellar populations at different redshifts and extinctions, to
provide through a Monte Carlo method the most likely range of stellar
population parameters (mainly ages and metallicities), extinctions, redshifts,
and stellar masses. To improve the diagnostic reliability, MUFFIT identifies
and removes from the analysis those bands that are significantly affected by
emission lines. We highlight that the retrieved age-metallicity locus for a
sample of early-type galaxies in ALHAMBRA at different stellar
mass bins are in very good agreement with the ones from SDSS spectroscopic
diagnostics. Moreover, a one-to-one comparison between the redshifts, ages,
metallicities, and stellar masses derived spectroscopically for SDSS and by
MUFFIT for ALHAMBRA reveals good qualitative agreements in all the parameters.
In addition, and using as input the results from photometric-redshift codes,
MUFFIT improves the photometric-redshift accuracy by -, and it
also detects nebular emissions in galaxies, providing physical information
about their strengths. Our results show the potential of multi-filter galaxy
data to conduct reliable stellar population studies with the appropiate
analysis techniques, as MUFFIT.Comment: 31 pages, 18 figures, accepted for publication in A&
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: Bayesian Photometric Redshifts with 23 bands for 3 squared degrees
The ALHAMBRA (Advance Large Homogeneous Area Medium Band Redshift
Astronomical) survey has observed 8 different regions of the sky, including
sections of the COSMOS, DEEP2, ELAIS, GOODS-N, SDSS and Groth fields using a
new photometric system with 20 contiguous ~ filters covering the
optical range, combining them with deep imaging. The observations,
carried out with the Calar Alto 3.5m telescope using the wide field (0.25 sq.
deg FOV) optical camera LAICA and the NIR instrument Omega-2000, correspond to
~700hrs on-target science images. The photometric system was designed to
maximize the effective depth of the survey in terms of accurate spectral-type
and photo-zs estimation along with the capability of identification of
relatively faint emission lines. Here we present multicolor photometry and
photo-zs for ~438k galaxies, detected in synthetic F814W images, complete down
to I~24.5 AB, taking into account realistic noise estimates, and correcting by
PSF and aperture effects with the ColorPro software. The photometric ZP have
been calibrated using stellar transformation equations and refined internally,
using a new technique based on the highly robust photometric redshifts measured
for emission line galaxies. We calculate photometric redshifts with the BPZ2
code, which includes new empirically calibrated templates and priors. Our
photo-zs have a precision of for I<22.5 and 1.4% for
22.5<I<24.5. Precisions of less than 0.5% are reached for the brighter
spectroscopic sample, showing the potential of medium-band photometric surveys.
The global shows a mean redshift =0.56 for I=0.86 for
I<24.5 AB. The data presented here covers an effective area of 2.79 sq. deg,
split into 14 strips of 58.5'x15.5' and represents ~32 hrs of on-target.Comment: The catalog data and a full resolution version of this paper is
available at https://cloud.iaa.csic.es/alhambra
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
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
Atopic dermatitis and indoor use of energy sources in cooking and heating appliances
Background: Atopic dermatitis (AD) prevalence has considerably increased worldwide in recent years. Studying indoor environments is particularly relevant, especially in industrialised countries where many people spend 80% of their time at home, particularly children. This study is aimed to identify the potential association between AD and the energy source (biomass, gas and electricity) used for cooking and domestic heating in a Spanish schoolchildren population.
Methods: As part of the ISAAC (International Study of Asthma and Allergies in Childhood) phase III study, a cross-sectional population-based survey was conducted with 21,355 6-to-7-year-old children from 8 Spanish ISAAC centres. AD prevalence, environmental risk factors and the use of domestic heating/cooking devices were assessed using the validated ISAAC questionnaire. Crude and adjusted odds ratios (cOR, aOR) and 95% confidence intervals (CIs) were obtained. A logistic regression analysis was performed (Chi-square test, p-valueâ<â0.05).
Results: It was found that the use of biomass systems gave the highest cORs, but only electric cookers showed a significant cOR of 1.14 (95% CI: 1.01-1.27). When the geographical area and the motherâs educational level were included in the logistic model, the obtained aOR values differed moderately from the initial cORs. Electric heating was the only type which obtained a significant aOR (1.13; 95% CI: 1.00-1.27). Finally, the model with all selected confounding variables (sex, BMI, number of siblings, motherâs educational level, smoking habits of parents, truck traffic and geographical area), showed aOR values which were very similar to those obtained in the previous adjusted logistic analysis. None of the results was statistically significant, but the use of electric heating showed an aOR close to significance (1.14; 95% CI: 0.99-1.31).
Conclusion: In our study population, no statistically significant associations were found between the type of indoor energy sources used and the presence of AD
Clustering of Dietary Patterns and Lifestyles among Spanish Children in the EsNuPI Study
Dietary patterns (DPs) are known to be tied to lifestyle behaviors. Understanding DPs
and their relationships with lifestyle factors can help to prevent children from engaging in unhealthy
dietary practices. We aimed to describe DPs in Spanish children aged 1 to <10 years and to
examine their associations with sociodemographic and lifestyle variables. The consumption of
toddler and young children milk formulas, enriched and fortified milk within the Spanish pediatric
population is increasing, and there is a lack of evidence whether the consumption of this type of milk
is causing an impact on nutrient intakes and if they are helping to reach the nutrient recommendations.
Within the Nutritional Study in the Spanish Pediatric Population (EsNuPI), we considered two study
cohorts and three different age groups in three year-intervals in each of them. The study cohort
included 740 children in a representative sample of the urban non-vegan Spanish population and 772 children in a convenience cohort of adapted milk consumers (AMS) (including follow-on formula,
toddlerâs milk, growing up milk, and fortified and enriched milks) who provided information about
sociodemographics, lifestyle, and dietary habits; a food frequency questionnaire was used for the latter.
Principal component analysis was performed to identify DPs from 18 food groups. Food groups
and sociodemographic/lifestyle variables were combined through a hierarchical cluster algorithm.
Three DPs predominated in every age group and study sample: a palatable energy-dense food dietary
pattern, and two Mediterranean-like DPs. However, children from the AMS showed a predominant
dietary pattern markedly related to the Mediterranean diet, with high consumption of cereals, fruits
and vegetables, as well as milk and dairy products. The age of children and certain lifestyle factors,
namely level of physical activity, parental education, and household income, correlated closely with
the dietary clusters. Thus, the findings provide insight into designing lifestyle interventions that
could reverse the appearance of unhealthy DPs in the Spanish child population
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