12,108 research outputs found
Dynamical Aspects of Lie--Poisson Structures
Quantum Groups can be constructed by applying the quantization by deformation
procedure to Lie groups endowed with a suitable Poisson bracket. Here we try to
develop an understanding of these structures by investigating dynamical systems
which are associated with this bracket. We look at and , as
submanifolds of a 4--dimensional phase space with constraints, and deal with
two classes of problems. In the first set of examples we consider some
hamiltonian systems associated with Lie-Poisson structures and we investigate
the equations of the motion. In the second set of examples we consider systems
which preserve the chosen bracket, but are dissipative. However in this
approach, they survive the quantization procedure.Comment: 17 pages, figures not include
From the fuzzy disc to edge currents in Chern-Simons Theory
We present a brief review of the fuzzy disc, the finite algebra approximating
functions on a disc, which we have introduced earlier. We also present a
comparison with recent papers of Balachandran, Gupta and
K\"urk\c{c}\"{u}o\v{g}lu, and of Pinzul and Stern, aimed at the discussion of
edge states of a Chern-Simons theory.Comment: 8 pages, 6 figures, Talk presented at ``Space-time and Fundamental
Interactions: Quantum Aspects'', conference in honour of A. P. Balachandran's
65th birthday. References added and one misprint correcte
On Reduced Time Evolution for Initially Correlated Pure States
A new method to deal with reduced dynamics of open systems by means of the
Schr\"odinger equation is presented. It allows one to consider the reduced time
evolution for correlated and uncorrelated initial conditions.Comment: accepted in Open Sys. Information Dy
Mesothelioma and thymic tumors: Treatment challenges in (outside) a network setting
The management of patients with mesothelioma and thymic malignancy requires continuous multidisciplinary expertise at any step of the disease. A dramatic improvement in our knowledge has occurred in the last few years, through the development of databases, translational research programs, and clinical trials. Access to innovative strategies represents a major challenge, as there is a lack of funding for clinical research in rare cancers and their rarity precludes the design of robust clinical trials that could lead to specific approval of drugs. In this context, patient-centered initiatives, such as the establishment of dedicated networks, are warranted. International societies, such as IMIG (International Mesothelioma Interest Group) and ITMIG (International Thymic Malignancy Interest Group) provide infrastructure for global collaboration, and there are many advantages to having strong regional groups working on the same issues. There may be regional differences in risk factors, susceptibility, management and outcomes. The ability to address questions both regionally as well as globally is ideal to develop a full understanding of mesothelioma and thymic malignancies. In Europe, through the integration of national networks with EURACAN, the collaboration with academic societies and international groups, the development of networks in thoracic oncology provides multiplex integration of clinical care and research, ultimately ensuring equal access to high quality care to all patients, with the opportunity of conducting high level clinical and translational research projects
An anisotropic numerical model for thermal hydraulic analyses: application to liquid metal flow in fuel assemblies
A CFD analysis has been carried out to study the thermal–hydraulic behavior of liquid metal coolant in a fuel assembly of triangular lattice. In order to obtain fast and accurate results, the isotropic two-equation RANS approach is often used in nuclear engineering applications. A different approach is provided by Non-Linear Eddy Viscosity Models (NLEVM), which try to take into account anisotropic effects by a nonlinear formulation of the Reynolds stress tensor. This approach is very promising, as it results in a very good numerical behavior and in a potentially better fluid flow description than classical isotropic models. An Anisotropic Shear Stress Transport (ASST) model, implemented into a commercial software, has been applied in previous studies, showing very trustful results for a large variety of flows and applications. In the paper, the ASST model has been used to perform an analysis of the fluid flow inside the fuel assembly of the ALFRED lead cooled fast reactor. Then, a comparison between the results of wall-resolved conjugated heat transfer computations and the results of a decoupled analysis using a suitable thermal wall-function previously implemented into the solver has been performed and presented
The Kirillov picture for the Wigner particle
We discuss the Kirillov method for massless Wigner particles, usually
(mis)named "continuous spin" or "infinite spin" particles. These appear in
Wigner's classification of the unitary representations of the Poincar\'e group,
labelled by elements of the enveloping algebra of the Poincar\'e Lie algebra.
Now, the coadjoint orbit procedure introduced by Kirillov is a prelude to
quantization. Here we exhibit for those particles the classical Casimir
functions on phase space, in parallel to quantum representation theory. A good
set of position coordinates are identified on the coadjoint orbits of the
Wigner particles; the stabilizer subgroups and the symplectic structures of
these orbits are also described.Comment: 19 pages; v2: updated to coincide with published versio
Identification from flight data of the Italian Unmanned Space vehicle
Identification methodologies for processing flight data are frequently used to validate and improve a pre-flight aerodynamic data-base and, specifically, to reduce the associated uncertainties. This paper describes the process applied for the identification of the aerodynamic model of the Italian Unmanned Space Vehicle. The identification problem is solved through a multi-step approach, where the aerodynamic coefficients are identified first and, in a following phase, a set of model parameters are updated. The methodology was applied to actual flight data, gathered during the second flight test performed by the Italian Aerospace Research Centre
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