7,416 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
Mid-infrared imaging- and spectro-polarimetric subarcsecond observations of NGC 1068
We present sub-arcsecond 7.513 m imaging- and spectro-polarimetric
observations of NGC 1068 using CanariCam on the 10.4-m Gran Telescopio
CANARIAS. At all wavelengths, we find:
(1) A 90 60 pc extended polarized feature in the northern ionization
cone, with a uniform 44 polarization angle. Its polarization
arises from dust and gas emission in the ionization cone, heated by the active
nucleus and jet, and further extinguished by aligned dust grains in the host
galaxy. The polarization spectrum of the jet-molecular cloud interaction at
24 pc from the core is highly polarized, and does not show a silicate
feature, suggesting that the dust grains are different from those in the
interstellar medium.
(2) A southern polarized feature at 9.6 pc from the core. Its
polarization arises from a dust emission component extinguished by a large
concentration of dust in the galaxy disc. We cannot distinguish between dust
emission from magnetically aligned dust grains directly heated by the jet close
to the core, and aligned dust grains in the dusty obscuring material
surrounding the central engine. Silicate-like grains reproduce the polarized
dust emission in this feature, suggesting different dust compositions in both
ionization cones.
(3) An upper limit of polarization degree of 0.3 per cent in the core. Based
on our polarization model, the expected polarization of the obscuring dusty
material is 0.1 per cent in the 813 m wavelength range. This
low polarization may be arising from the passage of radiation through aligned
dust grains in the shielded edges of the clumps.Comment: 17 pages, 10 figures, accepted for publication at MNRA
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
Bullying and gender violence at school: analysis of teacher perception
Nowadays gender violence and bullying continue to be considered a matter of great concern to society. This study analyses the teachers'' perceptions of these two social problems in the educational context. The interventions that are carried out from the school to prevent and respond to these behaviours are studied. From a methodological point of view, the study responds to the paradigm of qualitative research. We interviewed fifteen teachers of Early Childhood Education, Primary Education and Secondary Education of the Spanish educational system. The information collected indicates that teachers advocate a necessary reinforcement of emotional competencies and social skills from schools. In addition, they express their dissatisfaction due to the insufficient strategies applied from the school to respond to these violent behaviours. These results support any initiative that aims to train teachers to prevent possible cases of bullying or gender violence
Spatial effects on species persistence and implications for biodiversity
Natural ecosystems are characterized by striking diversity of form and
functions and yet exhibit deep symmetries emerging across scales of space, time
and organizational complexity. Species-area relationships and species-abundance
distributions are examples of emerging patterns irrespective of the details of
the underlying ecosystem functions. Here we present empirical and theoretical
evidence for a new macroecological pattern related to the distributions of
local species persistence times, defined as the timespans between local
colonizations and extinctions in a given geographic region. Empirical
distributions pertaining to two different taxa, breeding birds and herbaceous
plants, analyzed in a new framework that accounts for the finiteness of the
observational period, exhibit power-law scaling limited by a cut-off determined
by the rate of emergence of new species. In spite of the differences between
taxa and spatial scales of analysis, the scaling exponents are statistically
indistinguishable from each other and significantly different from those
predicted by existing models. We theoretically investigate how the scaling
features depend on the structure of the spatial interaction network and show
that the empirical scaling exponents are reproduced once a two-dimensional
isotropic texture is used, regardless of the details of the ecological
interactions. The framework developed here also allows to link the cut-off
timescale with the spatial scale of analysis, and the persistence-time
distribution to the species-area relationship. We conclude that the inherent
coherence obtained between spatial and temporal macroecological patterns points
at a seemingly general feature of the dynamical evolution of ecosystems.Comment: 5 pages, 5 figures. Supplementary materials avaliable on
http://www.pnas.org/content/108/11/434
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&
The optical system of the Tenerife Microwave Spectrometer: a window for observing the 10-20 GHz sky spectra
The TMS optical system is based on a decentered dual-reflector system in a
Gregorian configuration to observe with an angular resolution of less than
. The primary goal of the present study is to evaluate the final
design and verify that it satisfies the design requirements. We aim for low
cross-polarization (-30 dB), low sidelobe (-25 dB) levels, and a stable beam in
terms of shape (low ellipticity) and size over a full octave bandwidth (10-20
GHz). We performed both ray-tracing and full-wave simulations using the CST
Studio software in order to investigate the system behaviour. We gave special
attention to the beam frequency variation and polarization leakage. We have
characterized the effects on the radiation pattern produced by the cryostat
window. We present the final design of the TMS optical system, as well as a
complete study of the system's performance in terms of cross-polarization,
sidelobes, ellipticity and beamwidth. We discuss the effects of sidelobes and
study the need for a baffle.Comment: 30 pages, 15 figures. Accepted for publication in JINS
- …