1,470 research outputs found
Pool temperature stratification analysis in CIRCE-ICE facility with RELAP5-3D© model and comparison with experimental tests
In the frame of heavy liquid metal (HLM) technology development, CIRCE pool facility at ENEA/Brasimone Research Center was updated by installing ICE (Integral Circulation Experiments) test section which simulates the thermal behavior of a primary system in a HLM cooled pool reactor. The experimental campaign led to the characterization of mixed convection and thermal stratification in a HLM pool in safety relevant conditions and to the distribution of experimental data for the validation of CFD and system codes. For this purpose, several thermocouples were installed into the pool using 4 vertical supports in different circumferential position for a total of 119 thermocouples [1][2]. The aim of this work is to investigate the capability of the system code RELAP5-3D (c) to simulate mixed convection and thermal stratification phenomena in a HLM pool in steady state conditions by comparing code results with experimental data. The pool has been simulated by a 3D component divided into 1728 volumes, 119 of which are centered in the exact position of the thermocouples. Three dimensional model of the pool is completed with a mono-dimensional nodalization of the primary main flow path. The results obtained by code simulations are compared with a steady state condition carried out in the experimental campaign. Results of axial, radial and azimuthal temperature profile into the pool are in agreement with the available experimental data Furthermore the code is able to well simulate operating conditions into the main flow path of the test section
Flavour-Condensate-induced Breaking of Supersymmetry in Free Wess-Zumino Fluids
Recently we argued that a particular model of string-inspired quantum
space-time foam (D-foam) may induce oscillations and mixing among flavoured
particles. As a result, rather than the mass-eigenstate vacuum, the correct
ground state to describe the underlying dynamics is the flavour vacuum,
proposed some time ago by Blasone and Vitiello as a description of quantum
field theories with mixing. At the microscopic level, the breaking of
target-space supersymmetry is induced in our space-time foam model by the
relative transverse motion of brane defects. Motivated by these results, we
show that the flavour vacuum, introduced through an inequivalent representation
of the canonical (anti-) commutation relations, provides a vehicle for the
breaking of supersymmetry (SUSY) at a low-energy effective field theory level;
on considering the flavour-vacuum expectation value of the energy-momentum
tensor and comparing with the form of a perfect relativistic fluid, it is found
that the bosonic sector contributes as dark energy while the fermion
contribution is like dust. This indicates a strong and novel breaking of SUSY,
of a non-perturbative nature, which may characterize the low energy field
theory of certain quantum gravity models.Comment: Discussion added in sections II and IV on quantum-gravity induced
flavour mixing, references added, conclusions unchange
Countermeasures assessment of liquefaction-induced lateral deformation in a slope ground system
Liquefaction-induced lateral spreading may resul in significant damage and disruption of functionality for structures and slope groung system
SU(3)-breaking effects in kaon and hyperon semileptonic decays from lattice QCD
We discuss the result of a recent quenched lattice calculation of the K -> pi
vector form factor at zero-momentum transfer, relevant for the determination of
|V_us| from K-> pi l nu decays. Using suitable double ratios of three-point
correlation functions, we show that it is possible to calculate this quantity
at the percent-level precision. The leading quenched effects are corrected for
by means of quenched chiral perturbation theory. The final result, f+(0) =
0.960 +- 0.005_stat +- 0.007_syst, turns out to be in good agreement with the
old quark model estimate made by Leutwyler and Roos. In this paper, we discuss
the phenomenological impact of the lattice result for the extraction of |V_us|,
by updating the analysis of K -> pi l nu decays with the most recent
experimental data. We also present a preliminary lattice study of hyperon Sigma
-> n l nu decays, based on a similar strategy.Comment: 17 pages, 8 figures. Based on talks given at: DAFNE 2004: Physics at
meson factories, Laboratori Nazionali di Frascati (Italy), June 7-11, 2004;
VIII International Conference on "Electron-Nucleus Scattering", Marciana
Marina (Italy), June 21-25, 2004; Lattice 2004, Fermi National Accelerator
Laboratory, Batavia, Illinois (USA), June 21-26, 2004; ICHEP 2004, Beijing
(China), August 16-22, 200
Leading isospin-breaking corrections to pion, kaon and charmed-meson masses with Twisted-Mass fermions
We present a lattice computation of the isospin-breaking corrections to
pseudoscalar meson masses using the gauge configurations produced by the
European Twisted Mass collaboration with dynamical quarks at
three values of the lattice spacing ( and fm)
with pion masses in the range MeV. The strange and
charm quark masses are tuned at their physical values. We adopt the RM123
method based on the combined expansion of the path integral in powers of the
- and -quark mass difference () and of the
electromagnetic coupling . Within the quenched QED approximation,
which neglects the effects of the sea-quark charges, and after the
extrapolations to the physical pion mass and to the continuum and infinite
volume limits, we provide results for the pion, kaon and (for the first time)
charmed-meson mass splittings, for the prescription-dependent parameters
, \epsilon_\gamma(\overline{MS}, 2~\mbox{GeV}),
\epsilon_{K^0}(\overline{MS}, 2~\mbox{GeV}), related to the violations of the
Dashen's theorem, and for the light quark mass difference (\widehat{m}_d -
\widehat{m}_u)(\overline{MS}, 2~\mbox{GeV}).Comment: 47 pages, 20 figures, 4 tables; comments on QED and QCD splitting
prescriptions added; version to appear in PR
Inclusion of children with special educational needs and disabilities in physical education:A systematic review and meta-analysis of teachers’ attitudes
Research shows that teachers' attitudes toward physical education are associated with positive pupil outcomes. However, there is limited robust synthesis of evidence regarding teachers' attitudes toward working with vulnerable learners in physical education, particularly those with special educational needs and disabilities (SEND). This mixed methods systematic review and meta-analysis synthesizes the research evidence on teachers' attitudes towards the inclusion of children SEND children in physical education. Results indicated that teachers have largely favorable attitudes toward the inclusion of children with SEND in physical education, and that experience working with children with SEND was positively associated with such favorable attitudes. Further quantitative and qualitative synthesis also revealed that several different factors affect teachers’ attitudes – namely, knowledge and preparation, years of teaching experience, direct experience working with SEND children, type and degree of SEND, and collaboration and teaching support
First lattice calculation of the QED corrections to leptonic decay rates
The leading-order electromagnetic and strong isospin-breaking corrections to
the ratio of and decay rates are evaluated for the
first time on the lattice, following a method recently proposed. The lattice
results are obtained using the gauge ensembles produced by the European Twisted
Mass Collaboration with dynamical quarks. Systematics effects
are evaluated and the impact of the quenched QED approximation is estimated.
Our result for the correction to the tree-level decay
ratio is to be compared to the estimate based
on Chiral Perturbation Theory and adopted by the Particle Data Group.Comment: 5 pages, 6 figures; extended supplemental material with 1 table and 1
figure, results unchange
Achilles Tendon Rupture: Mechanisms of Injury, Principles of Rehabilitation and Return to Play
The Achilles tendon is the thickest, strongest and largest tendon in the human body, but despite its size and tensile strength, it frequently gets injured. Achilles tendon ruptures (ATRs) mainly occur during sports activities, and their incidence has increased over the last few decades. Achilles tendon tears necessitate a prolonged recovery time, sometimes leaving long-term functional limitations. Treatment options include conservative treatment and surgical repair. There is no consensus on which is the best treatment for ATRs, and their management is still controversial. Limited scientific evidence is available for optimized rehabilitation regimen and on the course of recovery after ATRs. Furthermore, there are no universally accepted outcomes regarding the return to play (RTP) process. Therefore, the aim of this narrative review is to give an insight into the mechanism of injuries of an ATR, related principles of rehabilitation, and RTP
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