3,613 research outputs found
Is the meson dynamically generated?
We study the problem whether the meson is generated `dynamically'. A
pedagogical analysis on the toy O(N) linear sigma model is performed and we
find that the large limit and the limit does not
commute. The sigma meson may not necessarily be described as a dynamically
generated resonance. On the contrary, the sigma meson may be more appropriately
described by considering it as an explicit degree of freedom in the effective
lagrangian.Comment: Contribution to ``Quark Confinement and Hadron Spectrum VII'', 2--7
Sept. 2006, Ponta Delgada, Acores, Portuga
A stationary free boundary problem modeling electrostatic MEMS
A free boundary problem describing small deformations in a membrane based
model of electrostatically actuated MEMS is investigated. The existence of
stationary solutions is established for small voltage values. A justification
of the widely studied narrow-gap model is given by showing that steady state
solutions of the free boundary problem converge toward stationary solutions of
the narrow-gap model when the aspect ratio of the device tends to zero
Is the meson a dynamically generated resonance? -- a lesson learned from the O(N) model and beyond
O(N) linear model is solvable in the large limit and hence
provides a useful theoretical laboratory to test various unitarization
approximations. We find that the large limit and the
limit do not commute. In order to get the correct large spectrum one has
to firstly take the large limit. We argue that the meson may
not be described as generated dynamically. On the contrary, it is most
appropriately described at the same level as the pions, i.e, both appear
explicitly in the effective lagrangian. Actually it is very likely the
meson responsible for the spontaneous chiral symmetry breaking in a lagrangian
with linearly realized chiral symmetry.Comment: 15 pages, 3 figurs; references added; discussions slightly modified;
revised version accepted by IJMP
Spin interference and Fano effect in electron transport through a mesoscopic ring side-coupled with a quantum dot
We investigate the electron transport through a mesoscopic ring side-coupled
with a quantum dot(QD) in the presence of Rashba spin-orbit(SO) interaction. It
is shown that both the Fano resonance and the spin interference effects play
important roles in the electron transport properties. As the QD level is around
the Fermi energy, the total conductance shows typical Fano resonance line
shape. By applying an electrical gate voltage to the QD, the total transmission
through the system can be strongly modulated. By threading the mesoscopic ring
with a magnetic flux, the time-reversal symmetry of the system is broken, and a
spin polarized current can be obtained even though the incident current is
unpolarized.Comment: 5 pages, 5 figure
Semi-leptonic and Non-leptonic meson decays to charmed mesons
We study the semi-leptonic and non-leptonic weak decays which are
governed by the transitions. The branching ratios, CP
asymmetries (CPA) and polarization fractions (FA) of non-leptonic decays are
investigated in the factorization approximation. The
form factors are estimated in the Salpeter method. Our estimation on branching
ratios generally agree with the existent experimental data. For CPA and
polarizations, comparisons among the FA results, the perturbative QCD
predictions and experimental data are made.Comment: 8 pages, 1 figures, 5 table
Consumer-Led Screening for Atrial Fibrillation:A Report From the mAFA-II Trial Long-Term Extension Cohort
BACKGROUND: There are limited data on mobile health detection of prevalent atrial fibrillation (AF) and its related risk factors over time. OBJECTIVES: This study aimed to report the trends on prevalent AF detection over time and risk factors, with a consumer-led photoplethysmography screening approach. METHODS: 3,499,461 subjects aged over 18 years, who use smart devices (Huawei Technologies Co.) were enrolled between October 26, 2018, and December 1, 2021. RESULTS: Among 2,852,217 subjects for AF screening, 12,244 subjects (0.43%; 83.2% male, mean age 57 ± 15 years) detected AF episodes. When compared with 2018, the risk (adjusted HRs, 95% CI) for monitored prevalent AF increased significantly for subjects when monitoring started in 2020 (adjusted HR: 1.34; 95% CI: 1.27-1.40; P 93% confirmation of detected AF episodes even for the low-risk general population, highlighting the increased risk for detecting prevalent AF and the need for modification of OSA that increase AF susceptibility. (Mobile Health [mHealth] Technology for Improved Screening, Patient Involvement and Optimizing Integrated Care in Atrial Fibrillation [mAFA (mAF-App) II study]; ChiCTR-OOC-17014138
Effects of transcutaneous electrical nerve stimulation on the regional cerebral blood flow of subjects with stroke : a preliminary study
2004-2005 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe
A parabolic free boundary problem modeling electrostatic MEMS
The evolution problem for a membrane based model of an electrostatically actuated microelectromechanical system (MEMS) is studied. The model describes the dynamics of the membrane displacement and the electric potential. The latter is a harmonic function in an angular domain, the deformable membrane being a part of the boundary. The former solves a heat equation with a right hand side that depends on the square of the trace of the gradient of the electric potential on the membrane. The resulting free boundary problem is shown to be well-posed locally in time. Furthermore, solutions corresponding to small voltage values exist globally in time while global existence is shown not to hold for high voltage values. It is also proven that, for small voltage values, there is an asymptotically stable steady-state solution. Finally, the small aspect ratio limit is rigorously justified
Acoustic black holes from supercurrent tunneling
We present a version of acoustic black holes by using the principle of the
Josephson effect. We find that in the case two superconductors and are
separated by an insulating barrier, an acoustic black hole may be created in
the middle region between the two superconductors. We discuss in detail how to
describe an acoustic black hole in the Josephson junction and write the metric
in the langauge of the superconducting electronics. Our final results infer
that for big enough tunneling current and thickness of the junction,
experimental verification of the Hawking temperature could be possible.Comment: 15pages,1 figure, to appear in IJMP
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