2,141 research outputs found
Selective diffusion for oriented pattern extraction: Application to tagged cardiac MRI enhancement
Anisotropic regularization PDE’s (Partial Differential Equation) raised a strong interest in the field of image processing. The benefit of PDE-based regularization methods lies in the ability to smooth data in a nonlinear way, allowing the preservation of important image features (contours, corners or other discontinuities). In this article, a selective diffusion approach based on the framework of Extreme Physical Information theory is presented. It is shown that this particular framework leads to a particular regularization PDE which makes the integration of prior knowledge possible within the diffusion scheme. As a proof of feasibility, results of oriented pattern extractions are first presented on ad hoc images and second on a particular medical application: Tagged cardiac MRI (Magnetic Resonance Imaging) enhancement
Thermodynamic study of heavy metals behavior during municipal waste incineration
The incineration of municipal solid waste (MSW) contributes significantly to the presence of heavy metals in urban area aerosols. It is thus important to ascertain the quantities and chemical forms of the heavy metals (HM) that are emitted from the incineration plant stacks. The behaviour of HM, which depends strongly on the thermal and chemical environments, was investigated herein with a modelling approach, consisting of several parts. First, a refuse bed combustion model was developed for simulating on-grate MSW incineration. It describes most of the physico-chemical and thermal phenomena occurring during waste combustion. Second, results from the bed model were taken as boundary conditions to perform 3D simulations of the post-combustion zone and of the boiler. The case studied was of the Strasbourg incineration plant. Finally, the local thermal conditions and the local elementary compositions of gas and solid phases obtained from these simulations were used to carry out thermodynamic calculations of the speciation of HM at each point in the incinerator. The results for four metals (Cd, Zn, Pb, Cr) are presented, discussed and compared to available data. Predicted species are in agreement with observations for volatile metals, except lead, whose volatilization seems overestimated
Exploitation de données oculométriques pour une modélisation du processus d’interprétation d’examens TEP/SCAN
National audienc
A review and critique of academic lab safety research
Over the past ten years, there have been several high-profile accidents in academic laboratories around the world, resulting in significant injuries and fatalities. The aftermath of these incidents is often characterized by calls for reflection and re-examination of the academic discipline’s approach to safety research and policy. However, the study of academic lab safety is still underdeveloped and necessary data about changes in safety attitudes and behaviours has not been gathered. This Review article critically examines the state of academic chemical safety research from a multifactorial stance, including research on the occurrence of lab accidents, contributors to lab accidents, the state of safety training research and the cultural barriers to conducting safety research and implementing safer lab practices. The Review concludes by delineating research questions that must be addressed to minimize future serious academic laboratory incidents as well as stressing the need for committed leadership from our research institutions
Epitaxial thin films of multiferroic Bi2FeCrO6 with B-site cationic order
Epitaxial thin films of Bi2FeCrO6 have been synthesized by pulsed laser
deposition on SrRuO3 on (100)- and (111)-oriented SrTiO3 substrates. Detailed
X-ray diffraction and cross-section transmission electron microscopy analysis
revealed a double perovskite crystal structure of the Bi2FeCrO6 epitaxial films
very similar to that of BiFeO3 along with a particularly noteworthy Fe3+/Cr3+
cation ordering along the [111] direction. The films contain no detectable
magnetic iron oxide impurities and have the correct cationic average
stoichiometry throughout their thickness. They however exhibit a slight
modulation in the Fe and Cr compositions forming complementary stripe patterns,
suggesting minor local excess or depletion of Fe and Cr. The epitaxial BFCO
films exhibit good ferroelectric and piezoelectric properties, in addition to
magnetic properties at room temperature, as well as an unexpected
crystallographic orientation dependence of their room temperature magnetic
properties. Our results qualitatively confirm the predictions made using the
ab-initio calculations: the double-perovskite structure of Bi2FeCrO6 films
exhibit a Fe3+/Cr3+ cation ordering and good multiferroic properties, along
with the unpredicted existence of magnetic ordering at room temperature.Comment: Accepted for publication in Journal of Materials Researc
Submillimetre dust polarisation and opacity in the HD163296 protoplanetary ring system
We present ALMA images of the sub-mm continuum polarisation and spectral
index of the protoplanetary ringed disk HD163296. The polarisation fraction at
870{\mu}m is measured to be ~0.9% in the central core and generally increases
with radius along the disk major axis. It peaks in the gaps between the dust
rings, and the largest value (~4%) is found between rings 1 and 2. The
polarisation vectors are aligned with the disk minor axis in the central core,
but become more azimuthal in the gaps, twisting by up to +/-9degrees in the gap
between rings 1 and 2. These general characteristics are consistent with a
model of self-scattered radiation in the ringed structure, without requiring an
additional dust alignment mechanism. The 870/1300{\mu}m dust spectral index
exhibits minima in the centre and the inner rings, suggesting these regions
have high optical depths. However, further refinement of the dust or the disk
model at higher resolution is needed to reproduce simultaneously the observed
degree of polarisation and the low spectral index.Comment: 5 pages +2 pages supplemental data. v2 - revised figures and final
values; conclusions unchange
Constraining the mass of the planet(s) sculpting a disk cavity. The intriguing case of 2MASS J16042165-2130284
The large cavities observed in the dust and gas distributions of transition
disks may be explained by planet-disk interactions. At ~145 pc, 2MASS
J16042165-2130284 (J1604) is a 5-12 Myr old transitional disk with different
gap sizes in the mm- and m-sized dust distributions (outer edges at ~79
and at ~63 au, respectively). Its CO emission shows a ~30 au cavity.
This radial structure suggests that giant planets are sculpting this disk. We
aim to constrain the masses and locations of plausible giant planets around
J1604. We observed J1604 with the Spectro-Polarimetric High-contrast Exoplanet
REsearch (SPHERE) at the Very Large Telescope (VLT), in IRDIFS\_EXT,
pupil-stabilized mode, obtaining YJH- band images with the integral field
spectrograph (IFS) and K1K2-band images with the Infra-Red Dual-beam Imager and
Spectrograph (IRDIS). The dataset was processed exploiting the angular
differential imaging (ADI) technique with high-contrast algorithms. Our
observations reach a contrast of ~12 mag from 0.15" to 0.80"
(~22 to 115 au), but no planet candidate is detected. The disk is directly
imaged in scattered light at all bands from Y to K, and it shows a red color.
This indicates that the dust particles in the disk surface are mainly
m-sized grains. We confirm the sharp dip/decrement in
scattered light in agreement with polarized light observations. Comparing our
images with a radiative transfer model we argue that the southern side of the
disk is most likely the nearest. This work represents the deepest search yet
for companions around J1604. We reach a mass sensitivity of from ~22 to ~115 au according to a hot start scenario. We propose
that a brown dwarf orbiting inside of ~15 au and additional Jovian planets at
larger radii could account for the observed properties of J1604 while
explaining our lack of detection.Comment: 10 pages, 7 Figures. Accepted for publication in A&A . Abridged
abstrac
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