8,878 research outputs found
Mgb2 Nonlinear Properties Investigated under Localized High RF Magnetic Field Excitation
In order to increase the accelerating gradient of Superconducting Radio
Frequency (SRF) cavities, Magnesium Diboride (MgB2) opens up hope because of
its high transition temperature and potential for low surface resistance in the
high RF field regime. However, due to the presence of the small superconducting
gap in the {\pi} band, the nonlinear response of MgB2 is potentially quite
large compared to a single gap s-wave superconductor (SC) such as Nb.
Understanding the mechanisms of nonlinearity coming from the two-band structure
of MgB2, as well as extrinsic sources, is an urgent requirement. A localized
and strong RF magnetic field, created by a magnetic write head, is integrated
into our nonlinear-Meissner-effect scanning microwave microscope [1]. MgB2
films with thickness 50 nm, fabricated by a hybrid physical-chemical vapor
deposition technique on dielectric substrates, are measured at a fixed location
and show a strongly temperature-dependent third harmonic response. We propose
that at least two mechanisms are responsible for this nonlinear response, one
of which involves vortex nucleation and penetration into the film. [1] T. M.
Tai, X. X. Xi, C. G. Zhuang, D. I. Mircea, S. M. Anlage, "Nonlinear Near-Field
Microwave Microscope for RF Defect Localization in Superconductors", IEEE
Trans. Appl. Supercond. 21, 2615 (2011).Comment: 6 pages, 6 figure
CP Violation in Fermion Pair Decays of Neutral Boson Particles
We study CP violation in fermion pair decays of neutral boson particles with
spin 0 or 1. We study a new asymmetry to measure CP violation in decays and discuss the possibility of measuring it
experimentally. For the spin-1 particles case, we study CP violation in the
decays of to octet baryon pairs. We show that these decays can
be used to put stringent constraints on the electric dipole moments of
, and .Comment: 14p, OZ-93/22, UM-93/89, OITS 51
Octet baryon masses in next-to-next-to-next-to-leading order covariant baryon chiral perturbation theory
We study the ground-state octet baryon masses and sigma terms using the
covariant baryon chiral perturbation theory (ChPT) with the
extended-on-mass-shell (EOMS) renormalization scheme up to
next-to-next-to-next-to-leading order (NLO). By adjusting the available 19
low-energy constants (LECs), a reasonable fit of the lattice quantum
chromodynamics (LQCD) results from the PACS-CS, LHPC, HSC, QCDSF-UKQCD and
NPLQCD collaborations is achieved. Finite-volume corrections to the lattice
data are calculated self-consistently. Our study shows that NLO BChPT
describes better the light quark mass evolution of the lattice data than the
NNLO BChPT does and the various lattice simulations seem to be consistent with
each other. We also predict the pion and strangeness sigma terms of the octet
baryons using the LECs determined in the fit of their masses. The predicted
pion- and strangeness-nucleon sigma terms are MeV and
MeV, respectively.Comment: 28 pages, 6 figures, minor revisions, typos corrected, version to
appear in JHE
The , , , , and as dynamically generated states from vector meson - vector meson interaction
We report on some recent developments in understanding the nature of the
low-lying mesonic resonances , , ,
, and . In particular we show that these five
resonances can be dynamically generated from vector meson--vector meson
interaction in a coupled-channel unitary approach, which utilizes the
phenomenologically very successful hidden-gauge Lagrangians to produce the
interaction kernel between two vector mesons, which is then unitarized by the
Bethe-Salpeter-equation method. The data on the strong decay branching ratios,
total decay widths, and radiative decay widths of these five states, and on
related decay processes can all be well described by such an approach.
We also make predictions, compare them with the results of earlier studies, and
highlight observables that if measured can be used to distinguish different
pictures of these resonances.Comment: 9 pages; Invited talk at workshop CHIRAL'10, Valencia (Spain), June
21-24, 201
Generation of spatially-separated spin entanglement in a triple quantum dot system
We propose a novel method for the creation of spatially-separated spin
entanglement by means of adiabatic passage of an external gate voltage in a
triple quantum dot system.Comment: 10 pages, 6 figure
Finite dimensional integrable Hamiltonian systems associated with DSI equation by Bargmann constraints
The Davey-Stewartson I equation is a typical integrable equation in 2+1
dimensions. Its Lax system being essentially in 1+1 dimensional form has been
found through nonlinearization from 2+1 dimensions to 1+1 dimensions. In the
present paper, this essentially 1+1 dimensional Lax system is further
nonlinearized into 1+0 dimensional Hamiltonian systems by taking the Bargmann
constraints. It is shown that the resulting 1+0 dimensional Hamiltonian systems
are completely integrable in Liouville sense by finding a full set of integrals
of motion and proving their functional independence.Comment: 10 pages, in LaTeX, to be published in J. Phys. Soc. Jpn. 70 (2001
Investigation of aged aerosols in size-resolved Asian dust storm particles transported from Beijing, China, to Incheon, Korea, using low-<i>Z</i> particle EPMA
This is the first study of Asian dust storm (ADS) particles collected in
Beijing, China, and Incheon, Korea, during a spring ADS event. Using a
seven-stage May impactor and a quantitative electron probe X-ray
microanalysis (ED-EPMA, also known as low-<i>Z</i> particle EPMA), we examined the
composition and morphology of 4200 aerosol particles at stages 1–6 (with a
size cut-off of 16, 8, 4, 2, 1, and 0.5 μm in equivalent
aerodynamic diameter, respectively) collected during an ADS event on 28–29
April 2005. The results showed that there were large differences in the
chemical compositions between particles in sample S1 collected in Beijing
immediately after the peak time of the ADS and in samples S2 and S3, which
were collected in Incheon approximately 5 h and 24 h later, respectively.
In sample S1, mineral dust particles accounted for more than 88% in
relative number abundance at stages 1–5; and organic carbon (OC) and reacted
NaCl-containing particles accounted for 24% and 32%, respectively,
at stage 6. On the other hand, in samples S2 and S3, in addition to
approximately 60% mineral dust, many sea spray aerosol (SSA) particles
reacted with airborne SO<sub>2</sub> and NO<sub>x</sub> (accounting for 24%
and 14% on average in samples S2 and S3, respectively), often mixed with
mineral dust, were encountered at stages 1–5, and (C, N, O, S)-rich
particles (likely a mixture of water-soluble organic carbon with
(NH<sub>4</sub>)<sub>2</sub>SO<sub>4</sub> and NH<sub>4</sub>NO<sub>3</sub>) were abundantly observed at
stage 6 (accounting for 68% and 51% in samples S2 and S3,
respectively). This suggests that an accumulation of sea-salt components on
individual ADS particles larger than 1 μm in diameter occurred and
many secondary aerosols smaller than 1 μm in diameter were formed
when the ADS particles passed over the Yellow Sea. In the reacted or aged
mineral dust and SSA particles, nitrate-containing and both nitrate- and
sulfate-containing species vastly outnumbered the sulfate-containing species,
implying that ambient NO<sub>x</sub> had a greater influence on the
atmospheric particles than SO<sub>2</sub> during this ADS episode. In addition to
partially- or totally-reacted CaCO<sub>3</sub>, reacted or aged Mg-containing
aluminosilicates were observed frequently in samples S2 and S3;
furthermore, a student's <i>t</i> test showed that both their atomic concentration
ratios of [Mg] / [Al] and [Mg] / [Si] were significantly elevated
(<i>P</i> < 0.05) compared to those in samples S1 (for [Mg] / [Al],
0.34 ± 0.09 and 0.40 ± 0.03 in samples S2 and S3, respectively,
vs. 0.24 ± 0.01 in sample S1; for [Mg] / [Si], 0.21 ± 0.05 and
0.22 ± 0.01 in samples S2 and S3, respectively, vs. 0.12 ± 0.02 in
sample S1). The significant increase of [Mg] / [Al] and [Mg] / [Si]
ratios in Mg-containing aluminosilicates indicates that a significant evolution or
aging must have occurred on the ADS particles in the marine atmosphere during
transport from China to Korea
Generalized r-matrix structure and algebro-geometric solution for integrable systems
The purpose of this paper is to construct a generalized r-matrix structure of
finite dimensional systems and an approach to obtain the algebro-geometric
solutions of integrable nonlinear evolution equations (NLEEs). Our starting
point is a generalized Lax matrix instead of usual Lax pair. The generalized
r-matrix structure and Hamiltonian functions are presented on the basis of
fundamental Poisson bracket. It can be clearly seen that various nonlinear
constrained (c-) and restricted (r-) systems, such as the c-AKNS, c-MKdV,
c-Toda, r-Toda, c-Levi, etc, are derived from the reduction of this structure.
All these nonlinear systems have {\it r}-matrices, and are completely
integrable in Liouville's sense. Furthermore, our generalized structure is
developed to become an approach to obtain the algebro-geometric solutions of
integrable NLEEs. Finally, the two typical examples are considered to
illustrate this approach: the infinite or periodic Toda lattice equation and
the AKNS equation with the condition of decay at infinity or periodic boundary.Comment: 41 pages, 0 figure
Activated NF-κB in Bone Marrow Mesenchymal Stem Cells from Systemic Lupus Erythematosus Patients Inhibits Osteogenic Differentiation Through Downregulating Smad Signaling
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