9,663 research outputs found
Dental Treatment under General Anesthesia in Healthy and Medically Compromised/Developmentally Disabled Children: A Comparative Study
Aim: To compare the type, number of procedures and working time of dental treatment provided under dental general anesthesia (DGA) in healthy and medically compromised/developmentally disabled children (MCDD children). Design: This cross-sectional prospective study involved 80 children divided into two groups of 40 children each. Group 1 consisted of healthy and Group 2 consisted of MCDD children. Results: Healthy children needed more working time than MCDD children, the means being 161±7.9 and 84±5.7 minutes, respectively (P= 0.0001). Operative dentistry and endodontic treatments showed a significant statistical difference (P= 0.0001). The means of procedures were 17±5.0 for healthy children and 11±4.8 for MCDD children (P= 0.0001). Conclusions: Healthy children needed more extensive dental treatment than MCDD children under DGA. The information from this sample of Mexican children could be used as reference for determining trends both within a facility as well as in comparing facilities in cross-population studies
Understanding the two-dimensional ionization structure in luminous infrared galaxies. A near-IR integral field spectroscopy perspective
We investigate the 2D excitation structure of the ISM in a sample of LIRGs
and Seyferts using near-IR IFS. This study extends to the near-IR the
well-known optical and mid-IR emission line diagnostics used to classify
activity in galaxies. Based on the spatially resolved spectroscopy of
prototypes, we identify in the [FeII]1.64/Br - H_2 1-0S(1)/Br
plane regions dominated by the different heating sources, i.e. AGNs, young MS
massive stars, and evolved stars i.e. supernovae. The ISM in LIRGs occupy a
wide region in the near-IR diagnostic plane from -0.6 to +1.5 and from -1.2 to
+0.8 (in log units) for the [FeII]/Br and H_2/Br line ratios,
respectively. The corresponding median(mode) ratios are +0.18(0.16) and
+0.02(-0.04). Seyferts show on average larger values by factors ~2.5 and ~1.4
for the [FeII]/Br and H_2/Br ratios, respectively. New areas
and relations in the near-IR diagnostic plane are defined for the compact, high
surface brightness regions dominated by AGN, young ionizing stars, and SNe
explosions, respectively. In addition, the diffuse regions affected by the AGN
radiation field cover an area similar to that of Seyferts, but with high values
in [FeII]/Br that are not as extreme. The extended, non-AGN diffuse
regions cover a wide area in the diagnostic diagram that overlaps that of
individual excitation mechanisms (i.e. AGN, young stars, and SNe), but with its
mode value to that of the young SF clumps. This indicates that the excitation
conditions of the diffuse ISM are likely due to a mixture of the different
ionization sources. The integrated line ratios in LIRGs show higher excitation
conditions i.e. towards AGNs, than those measured by the spatially resolved
spectroscopy. If this behaviour is representative, it would have clear
consequences when classifying high-z, SF galaxies based on their near-IR
integrated spectra.Comment: 18 pages, 13 figures, accepted for publication in A&
Granular mesoporous activated carbons from waste tires by cyclic oxygen chemisorption-desorption
This document is the accepted manuscript version of a published work that appeared in final form in Industrial and Engineering Chemistry Research, © American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see https://pubs.acs.org/doi/10.1021/ie201499hActivation upon cyclic oxygen chemisorption-desorption has proved to be an efficient way to develop porosity at low burn off from waste tires char. In this work the influence of particle size, desorption temperature, and the number of cycles is studied. Highest values of burnoff and specific surface area (S BET) are obtained for the largest particle diameter (3 mm average) and at intermediate desorption temperature (650 °C). In these conditions S BET values around 500 m 2/g can be achieved at burn-offs of about 30%, and close to 600 m 2/g at around 45% burnoff, with a mean pore size of 10 nm and a micropore volume close to 0.08 cm 3/g. Although the surface area is moderate, the low burnoff and high S BET/burnoff ratio achieved make it possible to maintain initial granular morphology of the particles even after 20 cycles of activationWe greatly appreciate finantial support from the Spanish Ministerio de Educacion y Ciencia through the project CTQ2009-0998
The Infrared Astronomical Characteristics of Roque de los Muchachos Observatory: precipitable water vapor statistics
The atmospheric water vapor content above the Roque de los Muchachos
Observatory (ORM) obtained from Global Positioning Systems (GPS) is presented.
GPS measurements have been evaluated by comparison with 940nm-radiometer
observations. Statistical analysis of GPS measurements points to ORM as an
observing site with suitable conditions for infrared (IR) observations, with a
median column of precipitable water vapor (PWV) of 3.8 mm. PWV presents a clear
seasonal behavior, being Winter and Spring the best seasons for IR
observations. The percentage of nighttime showing PWV values smaller than 3 mm
is over 60% in February, March and April. We have also estimated the temporal
variability of water vapor content at the ORM. A summary of PWV statistical
results at different astronomical sites is presented, recalling that these
values are not directly comparable as a result of the differences in the
techniques used to recorded the data.Comment: The paper contains 10 figures and 5 tables (28 pages) Accepted by
MNRA
Thermal impact from a thermoelectric power plant on a tropical coastal lagoon
Tropical coastal areas are sensitive ecosystems to climate change, mainly due to sea level rise and increasing water temperatures. Furthermore, they may be subject to numerous stresses, including heat releases from energy production. The Urias coastal lagoon (SE Gulf of California), a subtropical tidal estuary, receives cooling water releases from a thermoelectric power plant, urban and industrial wastes, and shrimp farm discharges. In order to evaluate the plant thermal impact, we measured synchronous temperature time series close to and far from the plant. Furthermore, in order to discriminate the thermal pollution impact from natural variability, we used a high-resolution hydrodynamic model forced by, amongst others, cooling water release as a continuous flow (7.78 m3 s?1) at 6 °C overheating temperature. Model results and field data indicated that the main thermal impact was temporally restricted to the warmest months, spatially restricted to the surface layers (above 0.6 m) and distributed along the shoreline within ?100 m of the release point. The methodology and results of this study can be extrapolated to tropical coastal lagoons that receive heat discharges.<br/
ALMA polarimetry measures magnetically aligned dust grains in the torus of NGC 1068
The obscuring structure surrounding active galactic nuclei (AGN) can be
explained as a dust and gas flow cycle that fundamentally connects the AGN with
their host galaxies. This structure is believed to be associated with dusty
winds driven by radiation pressure. However, the role of magnetic fields, which
are invoked in almost all models for accretion onto a supermassive black hole
and outflows, is not thoroughly studied. Here we report the first detection of
polarized thermal emission by means of magnetically aligned dust grains in the
dusty torus of NGC 1068 using ALMA Cycle 4 polarimetric dust continuum
observations (, pc; 348.5 GHz, m). The polarized torus
has an asymmetric variation across the equatorial axis with a peak polarization
of \% and position angle of (B-vector) at
pc east from the core. We compute synthetic polarimetric observations of
magnetically aligned dust grains assuming a toroidal magnetic field and
homogeneous grain alignment. We conclude that the measured 860 m continuum
polarization arises from magnetically aligned dust grains in an optically thin
region of the torus. The asymmetric polarization across the equatorial axis of
the torus arises from 1) an inhomogeneous optical depth, and 2) a variation of
the velocity dispersion, i.e. variation of the magnetic field turbulence at
sub-pc scales, from the eastern to the western region of the torus. These
observations and modeling constrain the torus properties beyond spectral energy
distribution results. This study strongly supports that magnetic fields up to a
few pc contribute to the accretion flow onto the active nuclei.Comment: 19 pages, 11 figures (Accepted for Publication to ApJ
Exploration of the treatment of fish-canning industry effluents by aqueous-phase reforming using Pt/C catalysts
In the current work, an exploratory study on the application of catalytic aqueous phase reforming (APR) to the treatment of fish-canning wastewater was performed for the first time. Pt/C (3%, w) catalysts were supported on different commercial carbon supports (two activated carbons and a carbon black) and tested in the APR of tuna-cooking wastewater. The effect of the supports and the reaction systems (batch vs. semi-continuous) on the performance of the catalysts was tested. The stability of the catalysts upon 3 successive reuse cycles was checked. TOC and COD removal ranged within 45-60%, which was ascribed to adsorption on the supports, hydrothermal carbonization and APR. The percentage of valuable gases (H2 and alkanes) reached up to 18% of the gas production showing the potential of APR for the valorization and treatment of wastewater. The production of gases is affected by the high chloride, acetate and phosphate concentrations, which may provoke catalyst deactivation. The use of a catalyst with a basic support significantly increased the production of gases and the H2 percentage in the gas fraction. Gas production was higher in semi-continuous compared to batch operation, maybe because the withdrawn gas displaces the reaction towards the products. The percentage of alkanes in the gas phase decreased upon successive catalyst reuse cycles at the expense of H2, which is probably due to sintering of Pt nanoparticles with the corresponding decrease of the number of low-coordinated Pt sites promoting methanation reactionsThe authors greatly appreciate financial support from Spanish MINECO (CTQ2015-65491-R). A. S. Oliveira thanks the Spanish MINECO for a research grant (BES-2016-077244
Near-Infrared Polarimetric Adaptive Optics Observations of NGC 1068: A torus created by a hydromagnetic outflow wind
We present J' and K' imaging linear polarimetric adaptive optics observations
of NGC 1068 using MMT-Pol on the 6.5-m MMT. These observations allow us to
study the torus from a magnetohydrodynamical (MHD) framework. In a 0.5" (30 pc)
aperture at K', we find that polarisation arising from the passage of radiation
from the inner edge of the torus through magnetically aligned dust grains in
the clumps is the dominant polarisation mechanism, with an intrinsic
polarisation of 7.0%2.2%. This result yields a torus magnetic field
strength in the range of 482 mG through paramagnetic alignment, and
139 mG through the Chandrasekhar-Fermi method. The measured
position angle (P.A.) of polarisation at K is found to be similar to the
P.A. of the obscuring dusty component at few parsec scales using infrared
interferometric techniques. We show that the constant component of the magnetic
field is responsible for the alignment of the dust grains, and aligned with the
torus axis onto the plane of the sky. Adopting this magnetic field
configuration and the physical conditions of the clumps in the MHD outflow wind
model, we estimate a mass outflow rate 0.17 M yr at 0.4
pc from the central engine for those clumps showing near-infrared dichroism.
The models used were able to create the torus in a timescale of 10
yr with a rotational velocity of 1228 km s at 0.4 pc. We conclude
that the evolution, morphology and kinematics of the torus in NGC 1068 can be
explained within a MHD framework.Comment: 14 pages, 4 figures, Accepted by MNRA
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