38,754 research outputs found
The quantization of the chiral Schwinger model based on the BFT-BFV formalism II
We apply an improved version of Batalin-Fradkin-Tyutin (BFT) Hamiltonian
method to the a=1 chiral Schwinger Model, which is much more nontrivial than
the a>1.\delta\xi$ in the measure. As a result, we explicitly
obtain the fully gauge invariant partition function, which includes a new type
of Wess-Zumino (WZ) term irrelevant to the gauge symmetry as well as usual WZ
action.Comment: 17 pages, To be published in J. Phys.
BFT Hamiltonian embedding for SU(3) Skyrmion
We newly apply the Batalin, Fradkin and Tyutin (BFT) formalism to the SU(3)
flavor Skyrmion model to investigate the Weyl ordering correction to the
structure of the hyperfine splittings of strange baryons. On the other hand,
the Berry phases and Casimir effects are also discussed.Comment: 14 pages, modified titl
Generalized BFT Formalism of Electroweak Theory in the Unitary Gauge
We systematically embed the SU(2)U(1) Higgs model in the unitary
gauge into a fully gauge-invariant theory by following the generalized BFT
formalism. We also suggest a novel path to get a first-class Lagrangian
directly from the original second-class one using the BFT fields.Comment: 14 pages, Latex, no figure
Performance of RF MEMS switches at low temperatures
The actuation voltage of microelectromechanical system (MEMS) \ud
metal switches was investigated at temperatures ranging from 10 to 290 K. The investigation shows a 50% increase in the actuation voltage at low temperature. A comparison has been made using a published model and showed similar increment of actuation voltage at low temperature
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Periodontitis-induced systemic inflammation exacerbates atherosclerosis partly via endothelial-mesenchymal transition in mice.
Growing evidence suggests close associations between periodontitis and atherosclerosis. To further understand the pathological relationships of these associations, we developed periodontitis with ligature placement around maxillary molars or ligature placement in conjunction with Porphyromonas gingivalis lipopolysaccharide injection at the ligature sites (ligature/P.g. LPS) in Apolipoprotein E knock out mice and studied the atherogenesis process in these animals. The mice were fed with high fat diet for 11 weeks and sacrificed for analyzing periodontitis, systemic inflammation, and atherosclerosis. Controls did not develop periodontitis or systemic inflammation and had minimal lipid deposition in the aortas, but mice receiving ligature or ligature/P.g. LPS showed severe periodontitis, systemic inflammation, and aortic plaque formation. The aortic plaque contained abundant macrophages and cells expressing both endothelial and mesenchymal cell markers. The severity of periodontitis was slightly higher in mice receiving ligature/P.g. LPS than ligature alone, and the magnitude of systemic inflammation and aortic plaque formation were also notably greater in the mice with ligature/P.g. LPS. These observations indicate that the development of atherosclerosis is due to systemic inflammation caused by severe periodontitis. In vitro, P.g. LPS enhanced the secretion of pro-inflammatory cytokines from macrophages and increased the adhesion of monocytes to endothelial cells by upregulating the expression of adhesion molecules from endothelial cells. Moreover, secretory proteins, such as TNF-α, from macrophages induced endothelial-mesenchymal transitions of the endothelial cells. Taken together, systemic inflammation induced by severe periodontitis might exacerbate atherosclerosis via, in part, causing aberrant functions of vascular endothelial cells and the activation of macrophages in mice
Detection of an exoplanet around the evolved K giant HD 66141
Aims. We have been carrying out a precise radial velocity (RV) survey for K
giants to search for and study the origin of the lowamplitude and long-periodic
RV variations.
Methods. We present high-resolution RV measurements of the K2 giant HD 66141
from December 2003 to January 2011 using the fiber-fed Bohyunsan Observatory
Echelle Spectrograph (BOES) at Bohyunsan Optical Astronomy Observatory (BOAO).
Results. We find that the RV measurements for HD 66141 exhibit a periodic
variation of 480.5 +/- 0.5 days with a semi-amplitude of 146.2 +/- 2.7 m/s. The
Hipparcos photometry and bisector velocity span (BVS) do not show any obvious
correlations with RV variations. We find indeed 706.4 +/- 35.0 day variations
in equivalent width (EW) measurements of H_alpha line and 703.0 +/- 39.4 day
variations in a space-born measurements 1.25{\mu} flux of HD 66141 measured
during COBE/DIRBE experiment. We reveal that a mean value of long-period
variations is about 705 +/- 53 days and the origin is a rotation period of the
star and variability that is caused by surface inhomogeneities. For the 480 day
periods of RV variations an orbital motion is the most likely explanation.
Assuming a stellar mass of 1.1 +/- 0.1 M_Sun? for HD 66141, we obtain a minimum
mass for the planetary companion of 6.0 +/- 0.3 M_Jup with an orbital
semi-major axis of 1.2 +/- 0.1 AU and an eccentricity of 0.07 +/- 0.03.Comment: 7 pages, 10 figures, 3 tables, accepted for publisation in Astronomy
& Astrophysic
Low-amplitude and long-period radial velocity variations in giants HD 3574, 63 Cygni, and HD 216946 (Research Note)
Aims. We study the low-amplitude and long-period variations in evolved stars
using precise radial velocity measurements. Methods. The high-resolution,
fiber-fed Bohyunsan Observatory Echelle Spectrograph (BOES) was used from
September 2004 to May 2014 as part of the exoplanet search program at the
Bohyunsan Optical Astronomy Observatory (BOAO). Results. We report the
detection of low-amplitude and long-period orbital radial velocity variations
in three evolved stars, HD 3574, 63 Cyg, and HD 216946. They have periods of
1061, 982, and 1382 days and semi-amplitudes of 376, 742, and 699 m/s,
respectively.Comment: 6 pages, 7 figures, 4 tables, accepted for publisation in Astronomy &
Astrophysic
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