45 research outputs found
Efectos de un incendio forestal sobre la respuesta hidrológica de la cuenca mediterránea de Arbúcies (cordilleras costeras catalanas, NE España)
We analyse the hydrological response of the Arbúcies River basin after a wildland fire occurred in August 1994, which burnt 15% of its drainage area. The Arbúcies River is located in the Catalan Coastal Ranges, draining an area of 106 km2. Deep sandy soils are predominant in the catchment. The study is based on rainfall and runoff records (1991-1997), from which twenty-six flood events were selected. River response, especially runoff volume and peak discharge, showed a remarkable increment for events occurred six months after the fire, in comparison with those of similar magnitude prior the fire. The higher the magnitude of the episodes the higher the degree of hydrological alteration. Maximum increment of peak discharge is 173%, which is susbtantially more important that that produced on the effective rainfall (+40%). Flood events tend to recover pre-fire hydrological response eighteen months after the fire.En agosto de 1994 un incendio forestal afectó al 15% de la superficie de la cuenca experimental de la riera de Arbúcies. Se trata de una cuenca mediterránea de 106 km2, en la que predominan las masas de frondosas y los suelos arenosos y profundos. A partir de los registros continuos de precipitación y caudal, anteriores y posteriores al incendio (1991-1997), se seleccionaron 26 episodios con el objetivo de detectar modificaciones en la respuesta hidrológica de la cuenca debidas a los efectos del fuego. Se ha detectado una mayor respuesta hidrológica para los episodios hasta seis meses después del incendio, tanto en volumen de escorrentía como en caudal máximo, siendo más acusado el incremento para los episodios de mayor magnitud. El incremento estimado en el caudal punta para el valor máximo del rango de registros de precipitación total es del 173%, mayor que el producido en la estimación de la precipitación neta, que es solamente del 40%. Los eventos ocurridos a partir de un año y medio después del incendio muestran una tendencia a la recuperación de la respuesta hidrológica previa al incendio
A panchromatic study of BLAST counterparts: total star-formation rate, morphology, AGN fraction and stellar mass
We carry out a multi-wavelength study of individual galaxies detected by the
Balloon-borne Large Aperture Submillimeter Telescope (BLAST) and identified at
other wavelengths, using data spanning the radio to the ultraviolet (UV). We
develop a Monte Carlo method to account for flux boosting, source blending, and
correlations among bands, which we use to derive deboosted far-infrared (FIR)
luminosities for our sample. We estimate total star-formation rates for BLAST
counterparts with z < 0.9 by combining their FIR and UV luminosities. Star
formation is heavily obscured at L_FIR > 10^11 L_sun, z > 0.5, but the
contribution from unobscured starlight cannot be neglected at L_FIR < 10^11
L_sun, z < 0.25. We assess that about 20% of the galaxies in our sample show
indication of a type-1 active galactic nucleus (AGN), but their submillimeter
emission is mainly due to star formation in the host galaxy. We compute stellar
masses for a subset of 92 BLAST counterparts; these are relatively massive
objects, with a median mass of ~10^11 M_sun, which seem to link the 24um and
SCUBA populations, in terms of both stellar mass and star-formation activity.
The bulk of the BLAST counterparts at z<1 appear to be run-of-the-mill
star-forming galaxies, typically spiral in shape, with intermediate stellar
masses and practically constant specific star-formation rates. On the other
hand, the high-z tail of the BLAST counterparts significantly overlaps with the
SCUBA population, in terms of both star-formation rates and stellar masses,
with observed trends of specific star-formation rate that support strong
evolution and downsizing.Comment: Accepted for publication in the Astrophysical Journal. 44 pages, 11
figures. The SED template for the derivation of L_FIR has changed (added new
figure) and the discussion on the stellar masses has been improved. The
complete set of full-color postage-stamps can be found at
http://blastexperiment.info/results_images/moncelsi
First Detection of Polarization of the Submillimetre Diffuse Galactic Dust Emission by Archeops
We present the first determination of the Galactic polarized emission at 353
GHz by Archeops. The data were taken during the Arctic night of February 7,
2002 after the balloon--borne instrument was launched by CNES from the Swedish
Esrange base near Kiruna. In addition to the 143 GHz and 217 GHz frequency
bands dedicated to CMB studies, Archeops had one 545 GHz and six 353 GHz
bolometers mounted in three polarization sensitive pairs that were used for
Galactic foreground studies. We present maps of the I, Q, U Stokes parameters
over 17% of the sky and with a 13 arcmin resolution at 353 GHz (850 microns).
They show a significant Galactic large scale polarized emission coherent on the
longitude ranges [100, 120] and [180, 200] deg. with a degree of polarization
at the level of 4-5%, in agreement with expectations from starlight
polarization measurements. Some regions in the Galactic plane (Gem OB1,
Cassiopeia) show an even stronger degree of polarization in the range 10-20%.
Those findings provide strong evidence for a powerful grain alignment mechanism
throughout the interstellar medium and a coherent magnetic field coplanar to
the Galactic plane. This magnetic field pervades even some dense clouds.
Extrapolated to high Galactic latitude, these results indicate that
interstellar dust polarized emission is the major foreground for PLANCK-HFI CMB
polarization measurement.Comment: Submitted to Astron. & Astrophys., 14 pages, 12 Fig., 2 Table
The Cosmic Microwave Background Anisotropy Power Spectrum measured by Archeops
We present a determination by the Archeops experiment of the angular power
spectrum of the cosmic microwave background anisotropy in 16 bins over the
multipole range l=15-350. Archeops was conceived as a precursor of the Planck
HFI instrument by using the same optical design and the same technology for the
detectors and their cooling. Archeops is a balloon-borne instrument consisting
of a 1.5 m aperture diameter telescope and an array of 21 photometers
maintained at ~100 mK that are operating in 4 frequency bands centered at 143,
217, 353 and 545 GHz. The data were taken during the Arctic night of February
7, 2002 after the instrument was launched by CNES from Esrange base (Sweden).
The entire data cover ~ 30% of the sky.This first analysis was obtained with a
small subset of the dataset using the most sensitive photometer in each CMB
band (143 and 217 GHz) and 12.6% of the sky at galactic latitudes above 30
degrees where the foreground contamination is measured to be negligible. The
large sky coverage and medium resolution (better than 15 arcminutes) provide
for the first time a high signal-to-noise ratio determination of the power
spectrum over angular scales that include both the first acoustic peak and
scales probed by COBE/DMR. With a binning of Delta(l)=7 to 25 the error bars
are dominated by sample variance for l below 200. A companion paper details the
cosmological implications.Comment: A&A Letter, in press, 6 pages, 4 figures, see also
http://www.archeops.or
Temperature and polarization angular power spectra of Galactic dust radiation at 353 GHz as measured by Archeops
We present the first measurement of temperature and polarization angular
power spectra of the diffuse emission of Galactic dust at 353 GHz as seen by
Archeops on 20% of the sky. The temperature angular power spectrum is
compatible with that provided by the extrapolation to 353 GHz of IRAS and DIRBE
maps using \cite{fds} model number 8. For Galactic latitudes deg
we report a 4 sigma detection of large scale ()
temperature-polarization cross-correlation and set upper limits to the and modes at . For Galactic latitudes deg, on the same
angular scales, we report a 2 sigma detection of temperature-polarization
cross-correlation . These
results are then extrapolated to 100 GHz to estimate the contamination in CMB
measurements by polarized diffuse Galactic dust emission. The signal is
then and for and 10 deg.
respectively. The upper limit on and becomes . If polarized dust emission at higher Galactic latitude cuts is
similar to the one we report here, then dust polarized radiation will be a
major foreground for determining the polarization power spectra of the CMB at
high frequencies above 100 GHz.Comment: 11 pages, 8 figures, submitted to A
Trends in socioeconomic inequalities in cancer mortality in Barcelona: 1992–2003
<p>Abstract</p> <p>Background</p> <p>The objective of this study was to assess trends in cancer mortality by educational level in Barcelona from 1992 to 2003.</p> <p>Methods</p> <p>The study population comprised Barcelona inhabitants aged 20 years or older. Data on cancer deaths were supplied by the system of information on mortality. Educational level was obtained from the municipal census. Age-standardized rates by educational level were calculated. We also fitted Poisson regression models to estimate the relative index of inequality (RII) and the Slope Index of Inequalities (SII). All were calculated for each sex and period (1992–1994, 1995–1997, 1998–2000, and 2001–2003).</p> <p>Results</p> <p>Cancer mortality was higher in men and women with lower educational level throughout the study period. Less-schooled men had higher mortality by stomach, mouth and pharynx, oesophagus, larynx and lung cancer. In women, there were educational inequalities for cervix uteri, liver and colon cancer. Inequalities of overall and specific types of cancer mortality remained stable in Barcelona; although a slight reduction was observed for some cancers.</p> <p>Conclusion</p> <p>This study has identified those cancer types presenting the greatest inequalities between men and women in recent years and shown that in Barcelona there is a stable trend in inequalities in the burden of cancer.</p
Global dataset of soil organic carbon in tidal marshes.
Tidal marshes store large amounts of organic carbon in their soils. Field data quantifying soil organic carbon (SOC) stocks provide an important resource for researchers, natural resource managers, and policy-makers working towards the protection, restoration, and valuation of these ecosystems. We collated a global dataset of tidal marsh soil organic carbon (MarSOC) from 99 studies that includes location, soil depth, site name, dry bulk density, SOC, and/or soil organic matter (SOM). The MarSOC dataset includes 17,454 data points from 2,329 unique locations, and 29 countries. We generated a general transfer function for the conversion of SOM to SOC. Using this data we estimated a median (± median absolute deviation) value of 79.2 ± 38.1 Mg SOC ha-1 in the top 30 cm and 231 ± 134 Mg SOC ha-1 in the top 1 m of tidal marsh soils globally. This data can serve as a basis for future work, and may contribute to incorporation of tidal marsh ecosystems into climate change mitigation and adaptation strategies and policies
Planck early results. VI. The High Frequency Instrument data processing
We describe the processing of the 336 billion raw data samples from the High
Frequency Instrument (HFI) which we performed to produce six temperature maps
from the first 295 days of Planck-HFI survey data. These maps provide an
accurate rendition of the sky emission at 100, 143, 217, 353, 545 and 857 GHz
with an angular resolution ranging from 9.9 to 4.4^2. The white noise level is
around 1.5 {\mu}K degree or less in the 3 main CMB channels (100--217GHz). The
photometric accuracy is better than 2% at frequencies between 100 and 353 GHz
and around 7% at the two highest frequencies. The maps created by the HFI Data
Processing Centre reach our goals in terms of sensitivity, resolution, and
photometric accuracy. They are already sufficiently accurate and
well-characterised to allow scientific analyses which are presented in an
accompanying series of early papers. At this stage, HFI data appears to be of
high quality and we expect that with further refinements of the data processing
we should be able to achieve, or exceed, the science goals of the Planck
project.Comment: Replaced by the accepted version for publication, as part of a
package of papers describing first results of the Planck mission The paper
with figures at full resolution and full color tables can also be downloaded
from the ESA site http://www.rssd.esa.int/Planc
Planck early results: first assessment of the High Frequency Instrument in-flight performance
The Planck High Frequency Instrument (HFI) is designed to measure the
temperature and polarization anisotropies of the Cosmic Microwave Background
and galactic foregrounds in six wide bands centered at 100, 143, 217, 353, 545
and 857 GHz at an angular resolution of 10' (100 GHz), 7' (143 GHz), and 5'
(217 GHz and higher). HFI has been operating flawlessly since launch on 14 May
2009. The bolometers cooled to 100 mK as planned. The settings of the readout
electronics, such as the bolometer bias current, that optimize HFI's noise
performance on orbit are nearly the same as the ones chosen during ground
testing. Observations of Mars, Jupiter, and Saturn verified both the optical
system and the time response of the detection chains. The optical beams are
close to predictions from physical optics modeling. The time response of the
detection chains is close to pre-launch measurements. The detectors suffer from
an unexpected high flux of cosmic rays related to low solar activity. Due to
the redundancy of Planck's observations strategy, the removal of a few percent
of data contaminated by glitches does not affect significantly the sensitivity.
The cosmic rays heat up significantly the bolometer plate and the modulation on
periods of days to months of the heat load creates a common drift of all
bolometer signals which do not affect the scientific capabilities. Only the
high energy cosmic rays showers induce inhomogeneous heating which is a
probable source of low frequency noise.Comment: Submitted to A&A. 22 pages, 6 tables, 21 figures. One of a set of
simultaneous papers for the Planck Missio
Planck Early Results: The Planck View of Nearby Galaxies
The all-sky coverage of the Planck Early Release Compact Source Catalogue
(ERCSC) provides an unsurpassed survey of galaxies at submillimetre (submm)
wavelengths, representing a major improvement in the numbers of galaxies
detected, as well as the range of far-IR/submm wavelengths over which they have
been observed. We here present the first results on the properties of nearby
galaxies using these data. We match the ERCSC catalogue to IRAS-detected
galaxies in the Imperial IRAS Faint Source Redshift Catalogue (IIFSCz), so that
we can measure the spectral energy distributions (SEDs) of these objects from
60 to 850 microns. This produces a list of 1717 galaxies with reliable
associations between Planck and IRAS, from which we select a subset of 468 for
SED studies, namely those with strong detections in the three highest frequency
Planck bands and no evidence of cirrus contamination. The SEDs are fitted using
parametric dust models to determine the range of dust temperatures and
emissivities. We find evidence for colder dust than has previously been found
in external galaxies, with T<20K. Such cold temperatures are found using both
the standard single temperature dust model with variable emissivity beta, or a
two dust temperature model with beta fixed at 2. We also compare our results to
studies of distant submm galaxies (SMGs) which have been claimed to contain
cooler dust than their local counterparts. We find that including our sample of
468 galaxies significantly reduces the distinction between the two populations.
Fits to SEDs of selected objects using more sophisticated templates derived
from radiative transfer models confirm the presence of the colder dust found
through parameteric fitting. We thus conclude that cold (T<20K) dust is a
significant and largely unexplored component of many nearby galaxies.Comment: 16 pages, 14 figure