912 research outputs found
Seebeck Coefficients in Nanoscale Junctions: Effects of Electron-vibration Scattering and Local Heating
We report first-principles calculations of inelastic Seebeck coefficients in
an aluminum monatomic junction. We compare the elastic and inelastic Seebeck
coefficients with and without local heating. In the low temperature regime, the
signature of normal modes in the profiles of the inelastic Seebeck effects is
salient. The inelastic Seebeck effects are enhanced by the normal modes, and
further magnified by local heating. In the high temperature regime, the
inelastic Seebeck effects are weakly suppressed due to the quasi-ballistic
transport.Comment: 3 Figure
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Tackling MARCKS-PIP3 circuit attenuates fibroblast activation and fibrosis progression.
Targeting activated fibroblasts, including myofibroblast differentiation, has emerged as a key therapeutic strategy in patients with idiopathic pulmonary fibrosis (IPF). However, there is no available therapy capable of selectively eradicating myofibroblasts or limiting their genesis. Through an integrative analysis of the regulator genes that are responsible for the activation of IPF fibroblasts, we noticed the phosphatidylinositol 4,5-bisphosphate (PIP2)-binding protein, myristoylated alanine-rich C-kinase substrate (MARCKS), as a potential target molecule for IPF. Herein, we have employed a 25-mer novel peptide, MARCKS phosphorylation site domain sequence (MPS), to determine if MARCKS inhibition reduces pulmonary fibrosis through the inactivation of PI3K/protein kinase B (AKT) signaling in fibroblast cells. We first observed that higher levels of MARCKS phosphorylation and the myofibroblast marker α-smooth muscle actin (α-SMA) were notably overexpressed in all tested IPF lung tissues and fibroblast cells. Treatment with the MPS peptide suppressed levels of MARCKS phosphorylation in primary IPF fibroblasts. A kinetic assay confirmed that this peptide binds to phospholipids, particularly PIP2, with a dissociation constant of 17.64 nM. As expected, a decrease of phosphatidylinositol (3,4,5)-trisphosphate pools and AKT activity occurred in MPS-treated IPF fibroblast cells. MPS peptide was demonstrated to impair cell proliferation, invasion, and migration in multiple IPF fibroblast cells in vitro as well as to reduce pulmonary fibrosis in bleomycin-treated mice in vivo. Surprisingly, we found that MPS peptide decreases α-SMA expression and synergistically interacts with nintedanib treatment in IPF fibroblasts. Our data suggest MARCKS as a druggable target in pulmonary fibrosis and also provide a promising antifibrotic agent that may lead to effective IPF treatments.-Yang, D. C., Li, J.-M., Xu, J., Oldham, J., Phan, S. H., Last, J. A., Wu, R., Chen, C.-H. Tackling MARCKS-PIP3 circuit attenuates fibroblast activation and fibrosis progression
R&D, Patent Arrangements, and Financial Performances: Evidence from Taiwan
In this study, we investigate the relationships among R&D, patent arrangements, and financial performances for the firms listed on the Taiwan Stock Exchange (TWSE). In particular, we apply Vector Autoregression (VAR) to examine the relationships of the listed firms classified as industries of Semiconductor, Computer and Peripheral Equipment, Optoelectronic, Communications and Internet, Electronic Parts & Components, Electronic Products Distribution, and Other Electronic, by the TWSE. In sum, we find the different lead-lag relationships among R&D, patent arrangements, and financial performances in different industries, indicating important insight into patent arrangements
Spin and charge pumping in magnetic tunnel junctions with precessing magnetization: A nonequilibrium Green function approach
We study spin and charge currents pumped by precessing magnetization of a
single ferromagnetic layer within F|I|N or F|I|F (F-ferromagnet; I-insulator;
N-normal-metal) multilayers of nanoscale thickness attached to two normal metal
electrodes with no applied bias voltage between them. Both simple
one-dimensional model, consisting of a single precessing spin and a potential
barrier as the "sample," and realistic three-dimensional devices are
investigated. In the rotating reference frame, where the magnetization appears
to be static, these junctions are mapped onto a four-terminal dc circuit whose
effectively half-metallic ferromagnetic electrodes are biased by the frequency
of microwave radiation driving magnetization precession at the
ferromagnetic resonance (FMR) conditions. We show that pumped spin current in
F|I|F junctions, diminished behind the tunnel barrier and increased in the
opposite direction, is filtered into charge current by the second layer to
generate dc pumping voltage of the order of V (at FMR frequency
GHz) in an open circuit. In F|I|N devices, several orders of
magnitude smaller charge current and the corresponding dc voltage appear
concomitantly with the pumped spin current due to barrier induced asymmetry in
the transmission coefficients connecting the four electrodes in the rotating
frame picture of pumping.Comment: 8 pages, 5 figure
A model of CP Violation from Extra Dimension
We construct a realistic model of CP violation in which CP is broken in the
process of dimensional reduction and orbifold compactification from a five
dimensional theories with gauge symmetry. CP
violation is a result of the Hosotani type gauge configuration in the higher
dimension.Comment: 5 page
Nonequilibrium spin transport on Au(111) surfaces
The well-known experimentally observed \textit{sp}-derived Au(111) Shockley
surface states with Rashba spin splitting are perfectly fit by an effective
tight-binding model, considering a two-dimensional hexagonal lattice with
-orbital and nearest neighbor hopping only. The extracted realistic band
parameters are then imported to perform the Landauer-Keldysh formalism to
calculate nonequilibrium spin transport in a two-terminal setup sandwiching a
Au(111) surface channel. Obtained results show strong spin density on the
Au(111) surface and demonstrate (i) intrinsic spin-Hall effect, (ii)
current-induced spin polarization, and (iii) Rashba spin precession, all of
which have been experimentally observed in semiconductor heterostructures, but
not in metallic surface states. We therefore urge experiments in the latter for
these spin phenomena.Comment: 5 pages, 3 figures, to be published in Phys. Rev.
Suspension of the fiber mode-cleaner launcher and measurement of the high extinction-ratio (10^{-9}) ellipsometer for the Q & A experiment
The Q & A experiment, first proposed and started in 1994, provides a feasible
way of exploring the quantum vacuum through the detection of vacuum
birefringence effect generated by QED loop diagram and the detection of the
polarization rotation effect generated by photon-interacting (pseudo-)scalar
particles. Three main parts of the experiment are: (1) Optics System (including
associated Electronic System) based on a suspended 3.5-m high finesse
Fabry-Perot cavity, (2) Ellipsometer using ultra-high extinction-ratio
polarizer and analyzer, and (3) Magnetic Field Modulation System for generating
the birefringence and the polarization rotation effect. In 2002, the Q & A
experiment achieved the Phase I sensitivity goal. During Phase II, we set (i)
to improve the control system of the cavity mirrors for suppressing the
relative motion noise, (ii) to enhance the birefringence signal by setting-up a
60-cm long 2.3 T transverse permanent magnet rotatable to 10 rev/s, (iii) to
reduce geometrical noise by inserting a polarization-maintaining optical fiber
(PM fiber) as a mode cleaner, and (iv) to use ultra-high extinction-ratio
(10^{-9}) polarizer and analyzer for ellipsometry. Here we report on (iii) &
(iv); specifically, we present the properties of the PM-fiber mode-cleaner, the
transfer function of its suspension system, and the result of our measurement
of high extinction-ratio polarizer and analyzer.Comment: 8 pages, 6 figures, presented in the 6th Edoardo Amaldi Conference on
Gravitational Waves, Okinawa, Japan, June 2005, and accepted by "Journal of
Physics: Conference Series". Modifications from version 2 were made based on
the referees' comments on figures. Ref. [31] were update
Ellipsometry noise spectrum, suspension transfer function measurement and closed-loop control of the suspension system in the Q & A experiment
The Q & A experiment, aiming at the detection of vacuum birefringence
predicted by quantum electrodynamics, consists mainly of a suspended 3.5 m
Fabry-Perot cavity, a rotating permanent dipole magnet and an ellipsometer. The
2.3 T magnet can rotate up to 10 rev/s, introducing an ellipticity signal at
twice the rotation frequency. The X-pendulum gives a good isolation ratio for
seismic noise above its main resonant frequency 0.3 Hz. At present, the
ellipsometry noise decreases with frequency, from 1*10^{-5} rad Hz^{-1/2} at 5
Hz, 2*10^{-6} rad Hz^{-1/2} at 20 Hz to 5*10^{-7} rad Hz^{-1/2} at 40 Hz. The
shape of the noise spectrum indicates possible improvement can be made by
further reducing the movement between the cavity mirrors. From the preliminary
result of yaw motion alignment control, it can be seen that some peaks due to
yaw motion of the cavity mirror was suppressed. In this paper, we first give a
schematic view of the Q & A experiment, and then present the measurement of
transfer function of the compound X-pendulum-double pendulum suspension. A
closed-loop control was carried out to verify the validity of the measured
transfer functions. The ellipsometry noise spectra with and without yaw
alignment control and the newest improvement is presented.Comment: 7 pages, 5 figures, presented in 6th Edoardo Amaldi Conference on
Gravitational Waves, June 2005, Okinawa Japan and submitted to Journal of
Physics: Conference Series. Some modifications are made according to the
referee's comments: mainly to explain the relation between the displacement
of cavity mirror and the ellipticity noise spectru
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