6,444 research outputs found
Determination in soils of PAH produced by combustion of biomass under different conditions
4 pages, 2 figures, 2 tables, 25 references.-- Instituto de Recursos Naturales y Agrobiologia, C.S.I.C., Apartado 1052, E-41080 Sevilla, SpainThe nature and concentrations in soils of polynuclear aromatic hydrocarbons (PAH) generated by combustion of pine biomass under different conditions was determined by gas chromatography-mass spectrometry after their enrichment by a simple clean-up procedure. The patterns of pyrogenic PAH, presumably generated by thermal aromatization of biogenic precursors, vary for each sample. When burned at moderate temperature for a long period of time the most abundant homologues generated were alkylated derivatives of naphthalene, whereas phenanthrene alkyl derivatives were predominant after a forest wildfire, where higher temperatures are reached in less time. More condensed PAH included in well-known priority pollutant lists were detected only in minor amounts. No long persistence of PAH was observed in some soil samples analysed.Peer reviewe
Integrated European materials programme for DEMO applications: recent achievements and challenges
Potential common radiation problems for components and diagnostics in future magnetic and inertial confinement fusion devices
This work aims at identifying common potential problems that future fusion devices will encounter for both magnetic (MC) and inertial (IC) confinement approaches in order to promote joint efforts and to avoid duplication of research
Physical properties of two low-luminosity z ~ 1.9 galaxies behind the lensing cluster AC 114
We present VLT/ISAAC near-infrared spectroscopy of two gravitationally-lensed
z ~ 1.9 galaxies, A2 and S2, located behind the cluster AC 114. Thanks to large
magnification factors, we have been successful in detecting rest-frame optical
emission lines in star-forming galaxies 1 to 2 magnitudes fainter than in
previous studies of Lyman break galaxies (LBGs) at z ~ 3. From the Ha
luminosity, we estimate star formation rates (SFRs) which are 7 to 15 times
higher than those inferred from the UV continuum flux at 1500 ang without dust
extinction correction. The behavior of S2 and A2 in terms of O/H and N/O
abundance ratios are very different, and they are also different from typical
LBGs at z ~ 3. S2 is a low-metallicity object (Z ~ 0.03 Zsun) with a low N/O
ratio, similar to those derived in the most metal-poor nearby HII galaxies. In
contrast, A2 is a high-metallicity galaxy (Z ~ 1.3 Zsun) with a high N/O
abundance ratio, similar to those derived in the most metal-rich starburst
nucleus galaxies. The virial masses, derived from emission-line widths, are 0.5
and 2.4 x 10^10 Msun, for S2 and A2 respectively. Thanks to the gravitational
amplification, the line profiles of S2 are spatially resolved, leading to a
velocity gradient of +- 240 km/s, which yields a dynamical mass of ~ 1.3 x
10^10 Msun within the inner 1 kpc radius. Combining these new data with the
sample of LBGs at z ~ 3, we conclude that these three galaxies exhibit
different physical properties in terms of SFRs, abundance and mass-to-light
ratios, and reddening. High-redshift galaxies of different luminosities could
thus have quite different star formation histories (abridged version).Comment: 11 pages, 8 figures. Accepted for publication in A&
Mapping the submillimeter spiral wave in NGC 6946
We have analysed SCUBA 850\mum images of the (near) face-on spiral galaxy NGC
6946, and found a tight correlation between dust thermal emission and molecular
gas. The map of visual optical depth relates well to the distribution of
neutral gas (HI+H2) and implies a global gas-to-dust ratio of 90. There is no
significant radial variation of this ratio: this can be understood, since the
gas content is dominated by far by the molecular gas. The latter is estimated
through the CO emission tracer, which is itself dependent on metallicity,
similarly to dust emission. By comparing the radial profile of our visual
optical depth map with that of the SCUBA image, we infer an emissivity (dust
absorption coefficient) at 850\mum that is 3 times lower than the value
measured by COBE in the Milky Way, and 9 times lower than in NGC 891. A
decomposition of the spiral structure half way out along the disk of NGC 6946
suggests an interarm optical depth of between 1 and 2. These surprisingly high
values represent 40-80% of the visual opacity that we measure for the arm
region (abridged).Comment: 12 pages, 9 figures, accepted in A&
ALMA Observations of Asteroid 3 Juno at 60 Kilometer Resolution
We present Atacama Large Millimeter/submillimeter Array (ALMA) 1.3 mm
continuum images of the asteroid 3 Juno obtained with an angular resolution of
0.042 arcseconds (60 km at 1.97 AU). The data were obtained over a single 4.4
hr interval, which covers 60% of the 7.2 hr rotation period, approximately
centered on local transit. A sequence of ten consecutive images reveals
continuous changes in the asteroid's profile and apparent shape, in good
agreement with the sky projection of the three-dimensional model of the
Database of Asteroid Models from Inversion Techniques. We measure a geometric
mean diameter of 259pm4 km, in good agreement with past estimates from a
variety of techniques and wavelengths. Due to the viewing angle and inclination
of the rotational pole, the southern hemisphere dominates all of the images.
The median peak brightness temperature is 215pm13 K, while the median over the
whole surface is 197pm15 K. With the unprecedented resolution of ALMA, we find
that the brightness temperature varies across the surface with higher values
correlated to the subsolar point and afternoon areas, and lower values beyond
the evening terminator. The dominance of the subsolar point is accentuated in
the final four images, suggesting a reduction in the thermal inertia of the
regolith at the corresponding longitudes, which are possibly correlated to the
location of the putative large impact crater. These results demonstrate ALMA's
potential to resolve thermal emission from the surface of main belt asteroids,
and to measure accurately their position, geometric shape, rotational period,
and soil characteristics.Comment: 8 pages, 3 figures, 2 tables, accepted for publication in the
Astrophysical Journal Letter
First Results from High Angular Resolution ALMA Observations Toward the HL Tau Region
We present Atacama Large Millimeter/submillimeter Array (ALMA) observations
from the 2014 Long Baseline Campaign in dust continuum and spectral line
emission from the HL Tau region. The continuum images at wavelengths of 2.9,
1.3, and 0.87 mm have unprecedented angular resolutions of 0.075 arcseconds (10
AU) to 0.025 arcseconds (3.5 AU), revealing an astonishing level of detail in
the circumstellar disk surrounding the young solar analogue HL Tau, with a
pattern of bright and dark rings observed at all wavelengths. By fitting
ellipses to the most distinct rings, we measure precise values for the disk
inclination (46.72pm0.05 degrees) and position angle (+138.02pm0.07 degrees).
We obtain a high-fidelity image of the 1.0 mm spectral index (), which
ranges from in the optically-thick central peak and two
brightest rings, increasing to 2.3-3.0 in the dark rings. The dark rings are
not devoid of emission, we estimate a grain emissivity index of 0.8 for the
innermost dark ring and lower for subsequent dark rings, consistent with some
degree of grain growth and evolution. Additional clues that the rings arise
from planet formation include an increase in their central offsets with radius
and the presence of numerous orbital resonances. At a resolution of 35 AU, we
resolve the molecular component of the disk in HCO+ (1-0) which exhibits a
pattern over LSR velocities from 2-12 km/s consistent with Keplerian motion
around a ~1.3 solar mass star, although complicated by absorption at low
blue-shifted velocities. We also serendipitously detect and resolve the nearby
protostars XZ Tau (A/B) and LkHa358 at 2.9 mm.Comment: 11 pages, 5 figures, 2 tables, accepted for publication in the
Astrophysical Journal Letter
ALMA Long Baseline Observations of the Strongly Lensed Submillimeter Galaxy HATLAS J090311.6+003906 at z=3.042
We present initial results of very high resolution Atacama Large
Millimeter/submillimeter Array (ALMA) observations of the =3.042
gravitationally lensed galaxy HATLAS J090311.6+003906 (SDP.81). These
observations were carried out using a very extended configuration as part of
Science Verification for the 2014 ALMA Long Baseline Campaign, with baselines
of up to 15 km. We present continuum imaging at 151, 236 and 290 GHz, at
unprecedented angular resolutions as fine as 23 milliarcseconds (mas),
corresponding to an un-magnified spatial scale of ~180 pc at z=3.042. The ALMA
images clearly show two main gravitational arc components of an Einstein ring,
with emission tracing a radius of ~1.5". We also present imaging of CO(10-9),
CO(8-7), CO(5-4) and H2O line emission. The CO emission, at an angular
resolution of ~170 mas, is found to broadly trace the gravitational arc
structures but with differing morphologies between the CO transitions and
compared to the dust continuum. Our detection of H2O line emission, using only
the shortest baselines, provides the most resolved detection to date of thermal
H2O emission in an extragalactic source. The ALMA continuum and spectral line
fluxes are consistent with previous Plateau de Bure Interferometer and
Submillimeter Array observations despite the impressive increase in angular
resolution. Finally, we detect weak unresolved continuum emission from a
position that is spatially coincident with the center of the lens, with a
spectral index that is consistent with emission from the core of the foreground
lensing galaxy.Comment: 9 pages, 5 figures and 3 tables, accepted for publication in the
Astrophysical Journal Letter
The ROSAT International X-ray/Optical Survey (RIXOS): source catalogue
We describe the ROSAT International X-ray/Optical Survey (RIXOS), a medium-sensitivity survey and optical identification of X-ray sources discovered in ROSAT high Galactic latitude fields (|b|>28°) and observed with the Position Sensitive Proportional Counter (PSPC) detector. The survey made use of the central 17 arcmin of each ROSAT field. A flux limit of 3×10−14 erg cm−2 s−1 (0.5–2 keV) was adopted for the survey, and a minimum exposure time of 8000 s was required for qualifying ROSAT observations. X-ray sources in the survey are therefore substantially above the detection threshold of each field used, and many contain enough counts to allow the X-ray spectral slope to be estimated.
Spectroscopic observations of potential counterparts were obtained of all sources down to the survey limit in 64 fields, totalling a sky area of 15.77 deg2. Positive optical identifications are made for 94 per cent of the 296 sources thus examined. A further 18 fields (4.44 deg2), containing 105 sources above the 3×10−14 erg cm−2 s−1 survey limit, are completely optically identified to a higher flux of 8×10−14 erg cm−2 s−1 (0.5–2 keV). Optical spectroscopic data are supplemented by deep CCD imaging of many sources to reveal the morphology of the optical counterparts, and objects too faint to register on Sky Survey plates. The faintest optical counterparts have R∼22.
This paper describes the survey method, and presents a catalogue of the RIXOS sources and their optical identifications. Finding charts based on Sky Survey data are given for each source, supplemented by CCD imaging where necessary
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Changes in health sciences students' perception of obstetric violence after an educational intervention
Background
Obstetric violence is a type of gender-based violence that is presented structurally. This type of violence has physical and psychological consequences for both the women who experience it and health professionals. The World Health Organization adds that health professionals need training to ensure that pregnant women are treated with compassion and dignity.
Objectives
The objective of the study was to evaluate health sciences students' perception of obstetric violence and to identify possible changes after an educational intervention.
Design
A pre-post quasi-experimental study was carried out between January and June 2019.
Settings and participants
Students of medicine and nursing from Jaume I University (Universitat Jaume I) (Spain).
Methods
An ad hoc scale comprising 33 items was designed to measure the students' perceptions. In addition, sociodemographic and control variables were collected. Descriptive analyses of the sample and the scale were carried out, and a bivariate analysis was performed.
Results
Of the students surveyed, 89.7% were women, and the majority was nursing students. Of the 33 items, 28 (84.84%) showed statistically significant changes in the pre-post-intervention measurement. Twenty-five of the 33 items (75.75%) showed a relationship with the sociodemographic variables of gender, field, course and ever having been pregnant.
Conclusion
This study shows the change in health sciences students' perceptions of obstetric violence after an educational intervention. In addition, the normalization of this type of violence was observed with the progression of training and with personal obstetric experience.Background
Obstetric violence is a type of gender-based violence that is presented structurally. This type of violence has physical and psychological consequences for both the women who experience it and health professionals. The World Health Organization adds that health professionals need training to ensure that pregnant women are treated with compassion and dignity
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