Is the σ\sigma meson dynamically generated?

We study the problem whether the $\sigma$ meson is generated `dynamically'. A pedagogical analysis on the toy O(N) linear sigma model is performed and we find that the large $N_c$ limit and the $m_\sigma\to \infty$ 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 f0(600)f_0(600) meson a dynamically generated resonance? -- a lesson learned from the O(N) model and beyond

O(N) linear $\sigma$ model is solvable in the large $N$ limit and hence provides a useful theoretical laboratory to test various unitarization approximations. We find that the large $N_c$ limit and the $m_\sigma\to \infty$ limit do not commute. In order to get the correct large $N_c$ spectrum one has to firstly take the large $N_c$ limit. We argue that the $f_0(600)$ 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 $\sigma$ 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 BB meson decays to charmed mesons

We study the semi-leptonic and non-leptonic $B$ weak decays which are governed by the $B\rightarrow D^{(*)}$ transitions. The branching ratios, CP asymmetries (CPA) and polarization fractions (FA) of non-leptonic decays are investigated in the factorization approximation. The $B\rightarrow D^{(*)}$ 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 $A$ and $B$ 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