19,053 research outputs found
Ergodic property of Markovian semigroups on standard forms of von Neumann algebras
We give sufficient conditions for ergodicity of the Markovian semigroups
associated to Dirichlet forms on standard forms of von Neumann algebras
constructed by the method proposed in Refs. [Par1,Par2]. We apply our result to
show that the diffusion type Markovian semigroups for quantum spin systems are
ergodic in the region of high temperatures where the uniqueness of the
KMS-state holds.Comment: 25 page
Quasinormal Ringing for Acoustic Black Holes at Low Temperature
We investigate a condensed matter ``black hole'' analogue, taking the
Gross-Pitaevskii (GP) equation as a starting point. The linearized GP equation
corresponds to a wave equation on a black hole background, giving quasinormal
modes under some appropriate conditions. We suggest that we can know the
detailed characters and corresponding geometrical information about the
acoustic black hole by observing quasinormal ringdown waves in the low
temperature condensed matters.Comment: 9 pages, 3 figures, PRD accepted versio
A statistical study of the post-impulsive-phase acceleration of flare-associated coronal mass ejections
It is now generally accepted that the impulsive acceleration of a coronal
mass ejection (CME) in the inner corona is closely correlated in time with the
main energy release of the associated solar flare. In this paper, we examine in
detail the post-impulsive-phase acceleration of a CME in the outer corona,
which is the phase of evolution immediately following the main impulsive
acceleration of the CME; this phase is believed to correspond to the decay
phase of the associated flare. This observational study is based on a
statistical sample of 247 CMEs that are associated with M- and X-class GOES
soft X-ray flares from 1996 to 2006. We find that, from many examples of
events, the CMEs associated with flares with long-decay time (or so-called
long-duration flares) tend to have positive post-impulsive-phase acceleration,
even though some of them have already obtained a high speed at the end of the
impulsive acceleration but do not show a deceleration expected from the
aerodynamic dragging of the background solar wind. On the other hand, the CMEs
associated with flares of short-decay time tend to have significant
deceleration. In the scattering plot of all events, there is a weak correlation
between CME post-impulsive-phase acceleration and flare decay time. The CMEs
deviated from the general trend are mostly slow or weak ones associated with
flares of short-decay time; the deviation is caused by the relatively stronger
solar wind dragging force for these events. The implications of our results on
CME dynamics and CME-flare relations are discussed.Comment: 32 pages, 9 figures, accepted for publication in Ap
Ultrasound attenuation and a P-B-T phase diagram of superfluid 3He in 98% aerogel
Longitudinal sound attenuation measurements in superfluid 3He in 98% aerogel
were conducted at pressures between 14 and 33 bar and in magnetic fields up to
4.44 kG. The temperature dependence of the ultrasound attenuation in the A-like
phase was determined for the entire superfluid region exploiting the field
induced meta-stable A-like phase at the highest field. In the lower field, the
A-B transition in aerogel was identified by a smooth jump in attenuation on
both cooling and warming. Based on the transitions observed on warming, a phase
diagram as a function of pressure (P), temperature (T) and magnetic field (B)
is constructed. We find that the A-B phase boundary in aerogel recedes in a
drastically different manner than in bulk in response to an increasing magnetic
field. The implications of the observed phase diagram are discussed.Comment: 9 pages, 13 figures, accepted to PR
Large X-ray Flares from LMC X-4: Discovery of Milli-hertz Quasi-periodic Oscillations and QPO-modulated Pulsations
We report the discovery of milli-hertz (mHz) quasi-periodic oscillations
(QPOs) and QPO-modulated pulsations during large X-ray flares from the
high-mass X-ray binary pulsar LMC X-4 using data from the Rossi X-Ray Timing
Explorer (RXTE). The lightcurves of flares show that, in addition to ~74 mHz
coherent pulsations, there exist two more time-varying temporal structures at
frequencies of ~0.65-1.35 and ~2-20 mHz. These relatively long-term structures
appear in the power density spectra as mHz QPOs and as well-developed sidebands
around the coherent pulse frequency as well, indicating that the amplitudes of
the coherent pulsation is modulated by those of the mHz QPOs. One interesting
feature is that, while the first flare shows symmetric sidebands around the
coherent pulse frequency, the second flare shows significant excess emission in
the lower-frequency sidebands due to the ~2-20 mHz QPOs. We discuss the origin
of the QPOs using a combination of the beat-frequency model and a modified
version of the Keplerian-frequency model. According to our discussion, it seems
to be possible to attribute the origin of the ~0.65-1.35 and ~2-20 mHz QPOs to
the beating between the rotational frequency of the neutron star and the
Keplerian frequency of large accreting clumps near the corotation radius and to
the orbital motion of clumps at Keplerian radii of 2-10 times 10^9 cm,
respectively.Comment: 12 pages, including 4 figures; accepted by ApJ Letter
Heart failure–induced activation of phospholipase iPLA2γ generates hydroxyeicosatetraenoic acids opening the mitochondrial permeability transition pore
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