614 research outputs found
Effect of cation size variance on spin and orbital order in Eu(LaY)VO
We have investigated the -ion ( = rare earth or Y) size variance effect
on spin/orbital order in Eu(LaY)VO. The
size variance disturbs one-dimensional orbital correlation in -type
spin/-type orbital ordered states and suppresses this spin/orbital order. In
contrast, it stabilizes the other spin/orbital order. The results of neutron
and resonant X-ray scattering denote that in the other ordered phase, the
spin/orbital patterns are -type/-type, respectively.Comment: 4 pages, 4 figures, accepted to Rapid Communication in Physical
Review
Relativistic Corrections to the Sunyaev-Zel'dovich Effect for Clusters of Galaxies. IV. Analytic fitting formula for the Numerical Results
We present an accurate analytic fitting formula for the numerical results for
the relativistic corrections to the thermal Sunyaev-Zel'dovich effect for
clusters of galaxies. The numerical results for the relativistic corrections
have been obtained by numerical integration of the collision term of the
Boltzmann equation. The fitting is carried out for the ranges 0.02 < theta_{e}
< 0.05 and 0 < X < 20, where theta_{e} = k_{B}T_{e}/m_{e}c^{2}, X =
omega/k_{B}T_{0}, T_{e} is the electron temperature, omega is the angular
frequency of the photon, and T_{0} is the temperature of the cosmic microwave
background radiation. The accuracy of the fitting is generally better than
0.1%. The present analytic fitting formula will be useful for the analyses of
the thermal Sunyaev-Zel'dovich effect for high-temperature galaxy clusters.Comment: 11 pages + 1 table + 2 figures, LaTeX with AASMS macro. Accepted by
Astrophysical Journal for publicatio
Dewetting of Glassy Polymer Films
Dynamics and morphology of hole growth in a film of power hardening
viscoplastic solid (yield stress ~ [strain-rate]^n) is investigated. At
short-times the growth is exponential and depends on the initial hole size. At
long-times, for n > 1/3, the growth is exponential with a different exponent.
However, for n < 1/3, the hole growth slows; the hole radius approaches an
asymptotic value as time tends to infinity. The rim shape is highly asymmetric,
the height of which has a power law dependence on the hole radius (exponent
close to unity for 0.25 < n < 0.4). The above results explain recent intriguing
experiments of Reiter, Phys. Rev. Lett, 87, 186101 (2001).Comment: 4 pages, 5 figures, RevTe
Phenomenological theory of a scalar electronic order: application to skutterudite PrFe4P12
By phenomenological Landau analysis, it is shown that a scalar order
parameter with the point-group symmetry explains most properties
associated with the phase transition in PrFeP at 6.5 K. The
scalar-order model reproduces magnetic and elastic properties in
PrFeP consistently such as (i) the anomaly of the magnetic
susceptibility and elastic constant at the transition temperature, (ii)
anisotropy of the magnetic susceptibility in the presence of uniaxial pressure,
and (iii) the anomaly in the elastic constant in magnetic field. An Ehrenfest
relation is derived which relates the anomaly of the magnetic susceptibility to
that of the elastic constant at the transition.Comment: 16 pages, 9 figure
Visualization of the Activity of Rac1 Small GTPase in a Cell
Rho family G proteins including Rac regulate a variety of cellular functions, such as morphology, motility, and gene expression. Here we developed a fluorescence resonance energy transfer-based analysis in which we could monitor the activity of Rac1. To detect fluorescence resonance energy transfer, yellow fluorescent protein fused Rac1 and cyan fluorescent protein fused Cdc42-Rac1-interaction-binding domain of Pak1 protein were used as intermolecular probes of FRET. The fluorophores were separated with linear unmixing method. The fluorescence resonance energy transfer efficiency was measured by acceptor photobleaching assisted assay. With these methods, the Rac1 activity was visualized in a cell. The present findings indicate that this approach is sensitive enough to achieve results similar to those from ratiometric fluorescence resonance energy transfer analysis
Slow dynamics near glass transitions in thin polymer films
The -process (segmental motion) of thin polystyrene films supported
on glass substrate has been investigated in a wider frequency range from
10 Hz to 10 Hz using dielectric relaxation spectroscopy and thermal
expansion spectroscopy. The relaxation rate of the -process increases
with decreasing film thickness at a given temperature above the glass
transition. This increase in the relaxation rate with decreasing film thickness
is much more enhanced near the glass transition temperature. The glass
transition temperature determined as the temperature at which the relaxation
time of the -process becomes a macroscopic time scale shows a distinct
molecular weight dependence. It is also found that the Vogel temperature has
the thickness dependence, i.e., the Vogel temperature decreases with decreasing
film thickness. The expansion coefficient of the free volume is
extracted from the temperature dependence of the relaxation time within the
free volume theory. The fragility index is also evaluated as a function of
thickness. Both and are found to decrease with decreasing film
thickness.Comment: 9 pages, 7 figures, and 2 table
Effect of Maraviroc Intensification on HIV-1-Specific T Cell Immunity in Recently HIV-1-Infected Individuals
Background
The effect of maraviroc on the maintenance and the function of HIV-1-specific T cell responses remains unknown.
Methods
Subjects recently infected with HIV-1 were randomized to receive anti-retroviral treatment with or without maraviroc intensification for 48 weeks, and were monitored up to week 60. PBMC and in vitro-expanded T cells were tested for responses to the entire HIV proteome by ELISpot analyses. Intracellular cytokine staining assays were conducted to monitor the (poly)-functionality of HIV-1-specific T cells. Analyses were performed at baseline and week 24 after treatment start, and at week 60 (3 months after maraviroc discontinuation).
Results
Maraviroc intensification was associated with a slower decay of virus-specific T cell responses over time compared to the non-intensified regimen in both direct ex-vivo as well as in in-vitro expanded cells. The effector function profiles of virus-specific CD8+ T cells were indistinguishable between the two arms and did not change over time between the groups.
Conclusions
Maraviroc did not negatively impact any of the measured parameters, but was rather associated with a prolonged maintenance of HIV-1-specific T cell responses. Maraviroc, in addition to its original effect as viral entry inhibitor, may provide an additional benefit on the maintenance of virus-specific T cells which may be especially important for future viral eradication strategies
Effect of Uniaxial Stress for Pressure-Induced Superconductor SrFe_2As_2
We report that the pressure-temperature phase diagram of single-crystalline
SrFeAs is easily affected by the hydrostaticity of a
pressure-transmitting medium. For all of the three mediums we used,
superconductivity with zero resistance appears, accompanied by the suppression
of an antiferromagnetic (orthorhombic) phase, but the critical pressure
was found to depend on the type of medium. was estimated to be 4.4 GPa
under almost hydrostatic condition, but it decreased to GPa with the
use of the medium already solidified at room temperature. The uniaxial stress
along the c-axis is suggested to aid in the suppression of the
antiferromagnetic (orthorhombic) phase. The pressure effect of BaFeAs
is also reported.Comment: 4 pages, 5 figures, to be published in J. Phys. Soc. Jpn. No.8 (2009
Structure, Photophysics and the Order-Disorder Transition to the Beta Phase in Poly(9,9-(di -n,n-octyl)fluorene)
X-ray diffraction, UV-vis absorption and photoluminescence (PL) spectroscopy
have been used to study the well-known order-disorder transition (ODT) to the
beta phase in poly(9,9-(di n,n-octyl)fluorene)) (PF8) thin film samples through
combination of time-dependent and temperature-dependent measurements. The ODT
is well described by a simple Avrami picture of one-dimensional nucleation and
growth but crystallization, on cooling, proceeds only after molecular-level
conformational relaxation to the so called beta phase. Rapid thermal quenching
is employed for PF8 studies of pure alpha phase samples while extended
low-temperature annealing is used for improved beta phase formation. Low
temperature PL studies reveal sharp Franck-Condon type emission bands and, in
the beta phase, two distinguishable vibronic sub-bands with energies of
approximately 199 and 158 meV at 25 K. This improved molecular level structural
order leads to a more complete analysis of the higher-order vibronic bands. A
net Huang-Rhys coupling parameter of just under 0.7 is typically observed but
the relative contributions by the two distinguishable vibronic sub-bands
exhibit an anomalous temperature dependence. The PL studies also identify
strongly correlated behavior between the relative beta phase 0-0 PL peak
position and peak width. This relationship is modeled under the assumption that
emission represents excitons in thermodynamic equilibrium from states at the
bottom of a quasi-one-dimensional exciton band. The crystalline phase, as
observed in annealed thin-film samples, has scattering peaks which are
incompatible with a simple hexagonal packing of the PF8 chains.Comment: Submitted to PRB, 12 files; 1 tex, 1 bbl, 10 eps figure
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