996 research outputs found
Temporal extensivity of Tsallis' entropy and the bound on entropy production rate
The Tsallis entropy, which is a generalization of the Boltzmann-Gibbs
entropy, plays a central role in nonextensive statistical mechanics of complex
systems. A lot of efforts have recently been made on establishing a dynamical
foundation for the Tsallis entropy. They are primarily concerned with nonlinear
dynamical systems at the edge of chaos. Here, it is shown by generalizing a
formulation of thermostatistics based on time averages recently proposed by
Carati [A. Carati, Physica A 348, 110 (2005)] that, whenever relevant, the
Tsallis entropy indexed by is temporally extensive: linear growth in time,
i.e., finite entropy production rate. Then, the universal bound on the entropy
production rate is shown to be . The property of the associated
probabilistic process, i.e., the sojourn time distribution, determining
randomness of motion in phase space is also analyzed.Comment: 25 pages, no figure
Optimal Covariant Measurement of Momentum on a Half Line in Quantum Mechanics
We cannot perform the projective measurement of a momentum on a half line
since it is not an observable. Nevertheless, we would like to obtain some
physical information of the momentum on a half line. We define an optimality
for measurement as minimizing the variance between an inferred outcome of the
measured system before a measuring process and a measurement outcome of the
probe system after the measuring process, restricting our attention to the
covariant measurement studied by Holevo. Extending the domain of the momentum
operator on a half line by introducing a two dimensional Hilbert space to be
tensored, we make it self-adjoint and explicitly construct a model Hamiltonian
for the measured and probe systems. By taking the partial trace over the newly
introduced Hilbert space, the optimal covariant positive operator valued
measure (POVM) of a momentum on a half line is reproduced. We physically
describe the measuring process to optimally evaluate the momentum of a particle
on a half line.Comment: 12 pages, 3 figure
Ground-state phase diagram of the Kondo lattice model on triangular-to-kagome lattices
We investigate the ground-state phase diagram of the Kondo lattice model with
classical localized spins on triangular-to-kagome lattices by using a
variational calculation. We identify the parameter regions where a
four-sublattice noncoplanar order is stable with a finite spin scalar chirality
while changing the lattice structure from triangular to kagome continuously.
Although the noncoplanar spin states appear in a wide range of parameters, the
spin configurations on the kagome network become coplanar as approaching the
kagome lattice; eventually, the scalar chirality vanishes for the kagome
lattice model.Comment: 7 pages, 3 figure
Application of exchange Monte Carlo method to ordering dynamics
We apply the exchange Monte Carlo method to the ordering dynamics of the
three-state Potts model with the conserved order parameter. Even for the deeply
quenched case to low temperatures, we have observed a rapid domain growth; we
have proved the efficiency of the exchange Monte Carlo method for the ordering
process. The late-stage growth law has been found to be for
the case of conserved order parameter of three-component system.Comment: 7 pages including 5 eps figures, to appear in New J. Phys.
http://www.njp.or
Planck Sunyaev-Zel'dovich Cluster Mass Calibration using Hyper Suprime-Cam Weak Lensing
Using 140 deg Subaru Hyper Suprime-Cam (HSC) survey data, we stack
the weak lensing (WL) signal around five Planck clusters found within the
footprint. This yields a 15 detection of the mean Planck cluster mass
density profile. The five Planck clusters span a relatively wide mass range,
with a mean mass of . The ratio of the stacked
Planck Sunyaev-Zel'dovich (SZ) mass to the stacked WL mass is . This mass bias is
consistent with previous WL mass calibrations of Planck clusters within the
errors. We discuss the implications of our findings for the calibration of SZ
cluster counts and the much discussed tension between Planck SZ cluster counts
and Planck CDM cosmology.Comment: 12 pages, 2 tables, 7 figures, accepted to PASJ special issu
Manganite charge and orbitally ordered and disordered states probed by Fe substitution into Mn site in LnBaMn1.96Fe0.04O5, LnBaMn1.96Fe0.04O6 and LnBaMn1.96Fe0.04O5.5 (Ln=Y, Gd, Sm, Nd, Pr, La)
The layered manganese oxides LnBaMn1.96Fe0.04Oy (Ln=Y, Gd, Sm, Nd, Pr, La)
have been synthesized for y=5, 5.5 and 6. In the oxygen-saturated state (y=6)
they exhibit the charge and orbital order at ambient temperature for Ln=Y, Gd,
Sm, but unordered eg-electronic system for Ln=La,Pr,Nd. Fourfold increase of
quadrupole splitting was observed owing to the charge and orbital ordering.
This is in agreement with the jumplike increase in distortion of the reduced
perovskite-like cell for the charge and orbitally ordered manganites compared
to the unordered ones. Substitution of 2 percents of Mn by Fe suppresses the
temperatures of structural and magnetic transitions by 20 to 50 K. Parameters
of the crystal lattices and the room-temperature M\"{o}ssbauer spectra were
studied on forty samples whose structures were refined within five symmetry
groups: P4/mmm, P4/nmm, Pm-3m, Icma and P2/m. Overwhelming majority of the Fe
species are undifferentiated in the M\"{o}ssbauer spectra for most of the
samples. Such the single-component spectra in the two-site structures are
explained by the preference of Fe towards the site of Mn(III) and by the
segmentation of the charge and orbitally ordered domains.Comment: 8 figures; figures 2 and 3 were revise
Plasticity of microvascular oxygenation control in rat fast-twitch muscle: effects of experimental creatine depletion
Aging, heart failure and diabetes each compromise the matching of O2 delivery (QO2)-to-metabolic requirements (O2 uptake, VO2) in skeletal muscle such that the O2 pressure driving blood-myocyte O2 flux (microvascular PO2, PmvO2) is reduced and contractile function impaired. In contrast, β-guanidinopropionic acid (β-GPA) treatment improves muscle contractile function, primarily in fast-twitch muscle (Moerland and Kushmerick, 1994). We tested the hypothesis that β-GPA (2% wt/BW in rat chow, 8 wk; n=14) would improve QO2-to-VO2 matching (elevated PmvO2) during contractions (4.5 V @ 1 Hz) in mixed (MG) and white (WG) portions of the gastrocnemius, both predominantly fast-twitch). Compared with control (CON), during contractions PmvO2 fell less following β-GPA (MG -54%, WG -26%, p<0.05), elevating steady-state PmvO2 (CON, MG: 10±2, WG: 9±1; β-GPA, MG 16±2, WG 18±2 mmHg, P<0.05). This reflected an increased QO2/VO2 ratio due primarily to a reduced VO2 in β-GPA muscles. It is likely that this adaptation helps facilitate the β-GPA-induced enhancement of contractile function in fast-twitch muscles
Strange filamentary structures ("fireballs") around a merger galaxy in the Coma cluster of galaxies
We found an unusual complex of narrow blue filaments, bright blue knots, and
H-alpha emitting filaments and clouds, which morphologically resembled a
complex of ``fireballs,'' extending up to 80 kpc south from an E+A galaxy RB199
in the Coma cluster. The galaxy has a highly disturbed morphology indicative of
a galaxy--galaxy merger remnant. The narrow blue filaments extend in straight
shapes toward the south from the galaxy, and several bright blue knots are
located at the southern ends of the filaments. The Rc band absolute magnitudes,
half light radii and estimated masses of the bright knots are -12 - -13 mag,
200 - 300 pc and 10^6-7 Msolar, respectively. Long, narrow H-alpha emitting
filaments are connected at the south edge of the knots. The average color of
the fireballs is B - Rc = 0.5, which is bluer than RB199 (B - R = 0.99),
suggesting that most of the stars in the fireballs were formed within several
times 10^8 yr. The narrow blue filaments exhibit almost no H-alpha emission.
Strong H-alpha and UV emission appear in the bright knots. These
characteristics indicate that star formation recently ceased in the blue
filaments and now continues in the bright knots. The gas stripped by some
mechanism from the disk of RB199 may be traveling in the intergalactic space,
forming stars left along its trajectory. The most plausible fireball formation
mechanism is ram pressure stripping by high-speed collision between the galaxy
and the hot intra-cluster medium. The fireballs may be a snapshot of diffuse
intra-cluster population formation, or halo star population formation in a
cluster galaxy.Comment: 13 pages, 14 figures, submitted to Ap
Fermionic Ghosts in Moyal String Field Theory
We complete the construction of the Moyal star formulation of bosonic open
string field theory (MSFT) by providing a detailed study of the fermionic ghost
sector. In particular, as in the case of the matter sector, (1) we construct a
map from Witten's star product to the Moyal product, (2) we propose a
regularization scheme which is consistent with the matter sector and (3) as a
check of the formalism, we derive the ghost Neumann coefficients algebraically
directly from the Moyal product. The latter satisfy the Gross-Jevicki nonlinear
relations even in the presence of the regulator, and when the regulator is
removed they coincide numerically with the expression derived from conformal
field theory. After this basic construction, we derive a regularized action of
string field theory in the Siegel gauge and define the Feynman rules. We give
explicitly the analytic expression of the off-shell four point function for
tachyons, including the ghost contribution. Some of the results in this paper
have already been used in our previous publications. This paper provides the
technical details of the computations which were omitted there.Comment: 65 pages, typos correcte
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