40,309 research outputs found
The correlations between the twin kHz QPO frequencies of LMXBs
We analyzed the recently published kHz QPO data in the neutron star low-mass
X-ray binaries (LMXBs), in order to investigate the different correlations of
the twin peak kilohertz quasi-eriodic oscillations (kHz QPOs) in bright Z
sources and in the less luminous Atoll sources. We find that a power-law
relation \no\sim\nt^{b} between the upper and the lower kHz QPOs with
different indices: 1.5 for the Atoll source 4U 1728-34 and
1.9 for the Z source Sco X-1. The implications of our results for
the theoretical models for kHz QPOs are discussed.Comment: 6 pages, accepted by MNRA
Excluded-Volume Effects in Tethered-Particle Experiments: Bead Size Matters
The tethered-particle method is a single-molecule technique that has been
used to explore the dynamics of a variety of macromolecules of biological
interest. We give a theoretical analysis of the particle motions in such
experiments. Our analysis reveals that the proximity of the tethered bead to a
nearby surface (the microscope slide) gives rise to a volume-exclusion effect,
resulting in an entropic force on the molecule. This force stretches the
molecule, changing its statistical properties. In particular, the proximity of
bead and surface brings about intriguing scaling relations between key
observables (statistical moments of the bead) and parameters such as the bead
size and contour length of the molecule. We present both approximate analytic
solutions and numerical results for these effects in both flexible and
semiflexible tethers. Finally, our results give a precise,
experimentally-testable prediction for the probability distribution of the
distance between the polymer attachment point and the center of the mobile
bead.Comment: 4 pages, 3 figure
Liquid-gas Phase Transition in Strange Hadronic Matter with Weak Y-Y Interaction
The liquid-gas phase transition in strange hadronic matter is reexamined by
using the new parameters about the interaction deduced from
recent observation of double hypernucleus. The
extended Furnstahl-Serot-Tang model with nucleons and hyperons is utilized. The
binodal surface, the limit pressure, the entropy, the specific heat capacity
and the Caloric curves are addressed. We find that the liquid-gas phase
transition can occur more easily in strange hadronic matter with weak Y-Y
interaction than that of the strong Y-Y interaction.Comment: 10 pages, 7 figure
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