848 research outputs found
Recommended from our members
ARMC 5 Variants and Risk of Hypertension in Blacks: MH- GRID Study.
Background We recently found that ARMC 5 variants may be associated with primary aldosteronism in blacks. We investigated a cohort from the MH - GRID (Minority Health Genomics and Translational Research Bio-Repository Database) and tested the association between ARMC 5 variants and blood pressure in black s. Methods and Results Whole exome sequencing data of 1377 black s were analyzed. Target single-variant and gene-based association analyses of hypertension were performed for ARMC 5, and replicated in a subset of 3015 individuals of African descent from the UK Biobank cohort. Sixteen rare variants were significantly associated with hypertension ( P=0.0402) in the gene-based (optimized sequenced kernel association test) analysis; the 16 and one other, rs116201073, together, showed a strong association ( P=0.0003) with blood pressure in this data set. The presence of the rs116201073 variant was associated with lower blood pressure. We then used human embryonic kidney 293 and adrenocortical H295R cells transfected with an ARMC 5 construct containing rs116201073 (c.*920T>C). The latter was common in both the discovery ( MH - GRID ) and replication ( UK Biobank) data and reached statistical significance ( P=0.044 [odds ratio, 0.7] and P=0.007 [odds ratio, 0.76], respectively). The allele carrying rs116201073 increased levels of ARMC5 mRNA , consistent with its protective effect in the epidemiological data. Conclusions ARMC 5 shows an association with hypertension in black s when rare variants within the gene are considered. We also identified a protective variant of the ARMC 5 gene with an effect on ARMC 5 expression confirmed in vitro. These results extend our previous report of ARMC 5's possible involvement in the determination of blood pressure in blacks
A numerical model for multigroup radiation hydrodynamics
We present in this paper a multigroup model for radiation hydrodynamics to
account for variations of the gas opacity as a function of frequency. The
entropy closure model (M1) is applied to multigroup radiation transfer in a
radiation hydrodynamics code. In difference from the previous grey model, we
are able to reproduce the crucial effects of frequency-variable gas opacities,
a situation omnipresent in physics and astrophysics. We also account for the
energy exchange between neighbouring groups which is important in flows with
strong velocity divergence. These terms were computed using a finite volume
method in the frequency domain. The radiative transfer aspect of the method was
first tested separately for global consistency (reversion to grey model) and
against a well established kinetic model through Marshak wave tests with
frequency dependent opacities. Very good agreement between the multigroup M1
and kinetic models was observed in all tests. The successful coupling of the
multigroup radiative transfer to the hydrodynamics was then confirmed through a
second series of tests. Finally, the model was linked to a database of
opacities for a Xe gas in order to simulate realistic multigroup radiative
shocks in Xe. The differences with the previous grey models are discussed.Comment: 27 pages, 11 figures, Accepted for publication in JQSR
Head and neck target delineation using a novel PET automatic segmentation algorithm
Purpose To evaluate the feasibility and impact of using a novel advanced PET auto-segmentation method in Head and Neck (H&N) radiotherapy treatment (RT) planning. Methods ATLAAS, Automatic decision Tree-based Learning Algorithm for Advanced Segmentation, previously developed and validated on pre-clinical data, was applied to 18F-FDG-PET/CT scans of 20 H&N patients undergoing Intensity Modulated Radiation Therapy. Primary Gross Tumour Volumes (GTVs) manually delineated on CT/MRI scans (GTVpCT/MRI), together with ATLAAS-generated contours (GTVpATLAAS) were used to derive the RT planning GTV (GTVpfinal). ATLAAS outlines were compared to CT/MRI and final GTVs qualitatively and quantitatively using a conformity metric. Results The ATLAAS contours were found to be reliable and useful. The volume of GTVpATLAAS was smaller than GTVpCT/MRI in 70% of the cases, with an average conformity index of 0.70. The information provided by ATLAAS was used to grow the GTVpCT/MRI in 10 cases (up to 10.6 mL) and to shrink the GTVpCT/MRI in 7 cases (up to 12.3 mL). ATLAAS provided complementary information to CT/MRI and GTVpATLAAS contributed to up to 33% of the final GTV volume across the patient cohort. Conclusions ATLAAS can deliver operator independent PET segmentation to augment clinical outlining using CT and MRI and could have utility in future clinical studies
Experimental And Topological Determination of the Pressure-Temperature Phase Diagram of Racemic Etifoxine, a Pharmaceutical Ingredient with Anxyolitic Properties
International audienc
Simulations of protostellar collapse using multigroup radiation hydrodynamics. I. The first collapse
Radiative transfer plays a major role in the process of star formation. Many
simulations of gravitational collapse of a cold gas cloud followed by the
formation of a protostellar core use a grey treatment of radiative transfer
coupled to the hydrodynamics. However, dust opacities which dominate extinction
show large variations as a function of frequency. In this paper, we used
frequency-dependent radiative transfer to investigate the influence of the
opacity variations on the properties of Larson's first core. We used a
multigroup M1 moment model in a 1D radiation hydrodynamics code to simulate the
spherically symmetric collapse of a 1 solar mass cloud core. Monochromatic dust
opacities for five different temperature ranges were used to compute Planck and
Rosseland means inside each frequency group. The results are very consistent
with previous studies and only small differences were observed between the grey
and multigroup simulations. For a same central density, the multigroup
simulations tend to produce first cores with a slightly higher radius and
central temperature. We also performed simulations of the collapse of a 10 and
0.1 solar mass cloud, which showed the properties of the first core to be
independent of the initial cloud mass, with again no major differences between
grey and multigroup models. For Larson's first collapse, where temperatures
remain below 2000 K, the vast majority of the radiation energy lies in the IR
regime and the system is optically thick. In this regime, the grey
approximation does a good job reproducing the correct opacities, as long as
there are no large opacity variations on scales much smaller than the width of
the Planck function. The multigroup method is however expected to yield more
important differences in the later stages of the collapse when high energy (UV
and X-ray) radiation is present and matter and radiation are strongly
decoupled.Comment: 9 pages, 5 figures, accepted for publication in A&
Numerical simulation of strongly nonlinear and dispersive waves using a Green-Naghdi model
We investigate here the ability of a Green-Naghdi model to reproduce strongly
nonlinear and dispersive wave propagation. We test in particular the behavior
of the new hybrid finite-volume and finite-difference splitting approach
recently developed by the authors and collaborators on the challenging
benchmark of waves propagating over a submerged bar. Such a configuration
requires a model with very good dispersive properties, because of the
high-order harmonics generated by topography-induced nonlinear interactions. We
thus depart from the aforementioned work and choose to use a new Green-Naghdi
system with improved frequency dispersion characteristics. The absence of dry
areas also allows us to improve the treatment of the hyperbolic part of the
equations. This leads to very satisfying results for the demanding benchmarks
under consideration
Alternating Tree Automata with Qualitative Semantics
We study alternating automata with qualitative semantics over infinite binary trees: Alternation means that two opposing players construct a decoration of the input tree called a run, and the qualitative semantics says that a run of the automaton is accepting if almost all branches of the run are accepting. In this article, we prove a positive and a negative result for the emptiness problem of alternating automata with qualitative semantics. The positive result is the decidability of the emptiness problem for the case of BĂŒchi acceptance condition. An interesting aspect of our approach is that we do not extend the classical solution for solving the emptiness problem of alternating automata, which first constructs an equivalent non-deterministic automaton. Instead, we directly construct an emptiness game making use of imperfect information. The negative result is the undecidability of the emptiness problem for the case of co-BĂŒchi acceptance condition. This result has two direct consequences: The undecidability of monadic second-order logic extended with the qualitative path-measure quantifier and the undecidability of the emptiness problem for alternating tree automata with non-zero semantics, a recently introduced probabilistic model of alternating tree automata
- âŠ