4,595 research outputs found
Multi-hp adaptive discontinuous Galerkin methods for simplified PN approximations of 3D radiative transfer in non-gray media
In this paper we present a multi-hp adaptive discontinuous Galerkin method for 3D simplified approximations of radiative transfer in non-gray media capable of reaching accuracies superior to most of methods in the literature. The simplified models are a set of differential equations derived based on asymptotic expansions for the integro-differential radiative transfer equation. In a non-gray media the optical spectrum is divided into a finite set of bands with constant absorption coefficients and the simplified approximations are solved for each band in the spectrum. At high temperature, boundary layers with different magnitudes occur for each wavelength in the spectrum and developing a numerical solver to accurately capture them is challenging for the conventional finite element methods. Here we propose a class of high-order adaptive discontinuous Galerkin methods using space error estimators. The proposed method is able to solve problems where 3D meshes contain finite elements of different kind with the number of equations and polynomial orders of approximation varying locally on the finite element edges, faces, and interiors. The proposed method has also the potential to perform both isotropic and anisotropic adaptation for each band in the optical spectrum. Several numerical results are presented to illustrate the performance of the proposed method for 3D radiative simulations. The computed results confirm its capability to solve 3D simplified approximations of radiative transfer in non-gray media
Nuclear and Non-Ionizing Energy-Loss for Coulomb Scattered Particles from Low Energy up to Relativistic Regime in Space Radiation Environment
In the space environment, instruments onboard of spacecrafts can be affected
by displacement damage due to radiation. The differential scattering cross
section for screened nucleus--nucleus interactions - i.e., including the
effects due to screened Coulomb nuclear fields -, nuclear stopping powers and
non-ionization energy losses are treated from about 50 keV/nucleon up to
relativistic energies.Comment: Accepted for publication in the Proceedings of the ICATPP Conference
on Cosmic Rays for Particle and Astroparticle Physics, Villa Olmo (Como,
Italy), 7--8 October, 2010, to be published by World Scientifi
The treatment of squamous anal carcinoma: guidelines of the Italian society of colo-rectal surgery
Can Einstein (rings) surf Gravitational Waves?
How does the appearance of a strongly lensed system change if a gravitational
wave is produced by the lens? In this work we address this question by
considering a supermassive black hole binary at the center of the lens emitting
gravitational waves propagating either colinearly or orthogonally to the line
of sight. Specializing to an Einstein ring configuration (where the source, the
lens and the observer are aligned), we show that the gravitational wave induces
changes on the ring's angular size and on the optical path of photons. The
changes are the same for a given pair of antipodal points on the ring, but
maximally different for any pair separated by . For realistic
lenses and binaries, we find that the change in the angular size of the
Einstein ring is dozens of orders of magnitude smaller than the precision of
current experiments. On the other hand, the difference in the optical path
induced on a photon by a gravitational wave propagating \textit{orthogonally}
to the line of sight triggers, at peak strain, time delays in the range seconds, making the chance of their detection (and thus the use of
Einstein rings as gravitational wave detectors) less hopeless.Comment: v2. Version accepted for publication in the Open Journal of
Astrophysics. 8 pages, four figures. Comments are welcome
Dualisation of the D=7 Heterotic String
The dualisation and the first-order formulation of the D=7 abelian Yang-Mills
supergravity which is the low energy effective limit of the D=7 fully Higssed
heterotic string is discussed. The non-linear coset formulation of the scalars
is enlarged to include the entire bosonic sector by introducing dual fields and
by constructing the Lie superalgebra which generates the dualized coset
element.Comment: 20 page
GEANT4 simulation of phase rotation for neutrino factory
We discuss a GEANT4 simulation of the phase rotation system for a neutrino factory. The comparison with the beam transport code PATH shows a good agreement. Preliminary results for the energy disposition in the cryostat of the superconducting 1.8 T solenoid are briefly presented
Proctology in the COVID-19 era: handle with care
The Italian outbreak of COVID-19 was
confirmed on 31 January 2020 when two
COVID-19-positive cases were reported
in Chinese tourists. At the beginning,
the vast majority of cases were reported
in the northern regions of Italy with
establishment of the so-called âred zoneâ.
On 9March 2020, the Italian prime minister
declared a nationwide lockdown to
strengthen the national health system
(Sistema Sanitario Nazionale). Italy has
one of the highest rates of infection
and mortality in the worl
Clinical and Pathophysiological Insights Into Immunological Mediated Glomerular Diseases in Childhood
The kidney is often the target of immune system dysregulation in the context of primary or systemic disease. In particular, the glomerulus represents the anatomical entity most frequently involved, generally as the expression of inflammatory cell invasion or circulant or in situ immune-complex deposition. Glomerulonephritis is the most common clinical and pathological manifestation of this involvement. There are no universally accepted classifications for glomerulonephritis. However, recent advances in our understanding of the pathophysiological mechanisms suggest the assessment of immunological features, biomarkers, and genetic analysis. At the same time, more accurate and targeted therapies have been developed. Data on pediatric glomerulonephritis are scarce and often derived from adult studies. In this review, we update the current understanding of the etiologic events and genetic factors involved in the pathogenesis of pediatric immunologically mediated primitive forms of glomerulonephritis, together with the clinical spectrum and prognosis. Possible new therapeutic targets are also briefly discussed
Efficacy of a U-shaped automatic electric toothbrush in dental plaque removal: A cross-over randomized controlled trial
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