594 research outputs found
` 3,5-bisphosphate production has pleiotropic effects on various membrane trafficking routes in Arabidopsis
Characterization of Pneumatic Artificial Muscle System in an Opposing Pair Configuration
Pneumatic artificial muscle (PAM) is a pneumatic actuator that commonly used in the biomimetic robotic devices in rehabilitation applications due to its advantageous in high powerto-weight ratio and high degree of safety in use characteristics. Several techniques exist in the literature for the PAM system modeling, and these include theoretical modeling, phenomenological modeling and empirical modeling. This paper focuses on explaining the experimental setup of an opposing pair configuration of PAM system, and gives an analysis of the pneumatic muscle system dynamic in the theoretical modeling. The simulated dynamic model is compared with the actual PAM system for the validation in the open-loop step and sinusoidal positioning responses and pressures. It is concluded that the simulation result is verified and agreed with the actual system
Is the brick-wall model unstable for a rotating background?
The stability of the brick wall model is analyzed in a rotating background.
It is shown that in the Kerr background without horizon but with an inner
boundary a scalar field has complex-frequency modes and that, however, the
imaginary part of the complex frequency can be small enough compared with the
Hawking temperature if the inner boundary is sufficiently close to the horizon,
say at a proper altitude of Planck scale. Hence, the time scale of the
instability due to the complex frequencies is much longer than the relaxation
time scale of the thermal state with the Hawking temperature. Since ambient
fields should settle in the thermal state in the latter time scale, the
instability is not so catastrophic. Thus, the brick wall model is well defined
even in a rotating background if the inner boundary is sufficiently close to
the horizon.Comment: Latex, 17 pages, 1 figure, accepted for publication in Phys. Rev.
Antimatter in the Universe
Cosmological models which predict a large amount of antimatter in the
Universe are reviewed. Observational signatures and searches for cosmic
antimatter are briefly considered. A short discussion of new long range forces
which might be associated with matter and antimatter is presented.Comment: 17 pages + 2 figure
ARPES Spectra of the Hubbard model
We discuss spectra calculated for the 2D Hubbard model in the intermediate
coupling regime with the dynamical cluster approximation, which is a
non-perturbative approach. We find a crossover from a normal Fermi liquid with
a Fermi surface closed around the Brillouin zone center at large doping to a
non-Fermi liquid for small doping. The crossover is signalled by a splitting of
the Fermi surface around the point of the 2D Brillouin zone, which
eventually leads to a hole-like Fermi surface closed around the point M. The
topology of the Fermi surface at low doping indicates a violation of
Luttinger's theorem. We discuss different ways of presenting the spectral data
to extract information about the Fermi surface. A comparison to recent
experiments will be presented.Comment: 8 pages, 7 color figures, uses RevTeX
Supernova Neutrinos, Neutrino Oscillations, and the Mass of the Progenitor Star
We investigate the initial progenitor mass dependence of the early-phase
neutrino signal from supernovae taking neutrino oscillations into account. The
early-phase analysis has advantages in that it is not affected by the time
evolution of the density structure of the star due to shock propagation or
whether the remnant is a neutron star or a black hole. The initial mass affects
the evolution of the massive star and its presupernova structure, which is
important for two reasons when considering the neutrino signal. First, the
density profile of the mantle affects the dynamics of neutrino oscillation in
supernova. Second, the final iron core structure determines the features of the
neutrino burst, i.e., the luminosity and the average energy. We find that both
effects are rather small. This is desirable when we try to extract information
on neutrino parameters from future supernova-neutrino observations. Although
the uncertainty due to the progenitor mass is not small for intermediate
(), we
can, nevertheless, determine the character of the mass hierarchy and whether
is very large or very small.Comment: 8 pages, 15 figure
Giant magnetothermopower of magnon-assisted transport in ferromagnetic tunnel junctions
We present a theoretical description of the thermopower due to
magnon-assisted tunneling in a mesoscopic tunnel junction between two
ferromagnetic metals. The thermopower is generated in the course of thermal
equilibration between two baths of magnons, mediated by electrons. For a
junction between two ferromagnets with antiparallel polarizations, the ability
of magnon-assisted tunneling to create thermopower depends on the
difference between the size of the majority and
minority band Fermi surfaces and it is proportional to a temperature dependent
factor where is the magnon Debye
energy. The latter factor reflects the fractional change in the net
magnetization of the reservoirs due to thermal magnons at temperature
(Bloch's law). In contrast, the contribution of magnon-assisted
tunneling to the thermopower of a junction with parallel polarizations is
negligible. As the relative polarizations of ferromagnetic layers can be
manipulated by an external magnetic field, a large difference results in a magnetothermopower effect. This
magnetothermopower effect becomes giant in the extreme case of a junction
between two half-metallic ferromagnets, .Comment: 9 pages, 4 eps figure
Equation of state and phonon frequency calculations of diamond at high pressures
The pressure-volume relationship and the zone-center optical phonon frequency
of cubic diamond at pressures up to 600 GPa have been calculated based on
Density Functional Theory within the Local Density Approximation and the
Generalized Gradient Approximation. Three different approaches, viz. a
pseudopotential method applied in the basis of plane waves, an all-electron
method relying on Augmented Plane Waves plus Local Orbitals, and an
intermediate approach implemented in the basis of Projector Augmented Waves
have been used. All these methods and approximations yield consistent results
for the pressure derivative of the bulk modulus and the volume dependence of
the mode Grueneisen parameter of diamond. The results are at variance with
recent precise measurements up to 140 GPa. Possible implications for the
experimental pressure determination based on the ruby luminescence method are
discussed.Comment: 10 pages, 6 figure
Update on biomarkers in neuromyelitis optica
Neuromyelitis optica (NMO) (and NMO spectrum disorder) is an autoimmune inflammatory disease of the CNS primarily affecting spinal cord and optic nerves. Reliable and sensitive biomarkers for onset, relapse, and progression in NMO are urgently needed because of the heterogeneous clinical presentation, severity of neurologic disability following relapses, and variability of therapeutic response. Detecting aquaporin-4 (AQP4) antibodies (AQP4-IgG or NMO-IgG) in serum supports the diagnosis of seropositive NMO. However, whether AQP4-IgG levels correlate with disease activity, severity, response to therapy, or long-term outcomes is unclear. Moreover, biomarkers for patients with seronegative NMO have yet to be defined and validated. Collaborative international studies hold great promise for establishing and validating biomarkers that are useful in therapeutic trials and clinical management. In this review, we discuss known and potential biomarkers for NMO
Exploring flavor structure of supersymmetry breaking from rare B decays and unitarity triangle
We study effects of supersymmetric particles in various rare B decay
processes as well as in the unitarity triangle analysis. We consider three
different supersymmetric models, the minimal supergravity, SU(5) SUSY GUT with
right-handed neutrinos, and the minimal supersymmetric standard model with U(2)
flavor symmetry. In the SU(5) SUSY GUT with right-handed neutrinos, we consider
two cases of the mass matrix of the right-handed neutrinos. We calculate direct
and mixing-induced CP asymmetries in the b to s gamma decay and CP asymmetry in
B_d to phi K_S as well as the B_s--anti-B_s mixing amplitude for the unitarity
triangle analysis in these models. We show that large deviations are possible
for the SU(5) SUSY GUT and the U(2) model. The pattern and correlations of
deviations from the standard model will be useful to discriminate the different
SUSY models in future B experiments.Comment: revtex4, 36 pages, 10 figure
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