4,620 research outputs found
Rheology of a Supercooled Polymer Melt
Molecular dynamics simulations are performed for a polymer melt composed of
short chains in quiescent and sheared conditions. The stress relaxation
function exhibits a stretched exponential form in a relatively early
stage and ultimately follows the Rouse function in quiescent supercooled state.
Transient stress evolution after application of shear obeys the linear growth
for strain less than 0.1 and then saturates into a
non-Newtonian viscosity. In steady states, strong shear-thinning and elongation
of chains into ellipsoidal shapes are found at extremely small shear. A glassy
component of the stress is much enhanced in these examples.Comment: 4 pages, 5 figure
Analysis for practical realization of number-state manipulation by number-sum Bell measurement with linear optics
We analyze the linear optical realization of number-sum Bell measurement and
number-state manipulation by taking into account the realistic experimental
situation, specifically imperfectness of single-photon detector. The present
scheme for number-state manipulation is based on the number-sum Bell
measurement, which is implemented with linear optical elements, i.e., beam
splitters, phase shifters and zero-one-photon detectors. Squeezed vacuum states
and coherent states are used as optical sources. The linear optical Bell state
detector is formulated quantum theoretically with a probability operator
measure. Then, the fidelity of manipulation and preparation of number-states,
particularly for qubits and qutrits, is evaluated in terms of the quantum
efficiency and dark count of single-photon detector. It is found that a high
fidelity is achievable with small enough squeezing parameters and coherent
state amplitudes.Comment: 13 pages, 9 figure
Simultaneous constraints on the growth of structure and cosmic expansion from the multipole power spectra of the SDSS DR7 LRG sample
The anisotropic galaxy clustering on large scales provides us with a unique
opportunity to probe into the gravity theory through the redshift-space
distortions (RSDs) and the Alcock-Paczynski effect. Using the multipole power
spectra up to hexadecapole (ell=4), of the Luminous Red Galaxy (LRG) sample in
the data release 7 (DR7) of the Sloan Digital Sky Survey II (SDSS-II), we
obtain simultaneous constraints on the linear growth rate f, angular diameter
distance D_A, and Hubble parameter H at redshift z = 0.3. For this purpose, we
first extensively examine the validity of a theoretical model for the
non-linear RSDs using mock subhalo catalogues from N-body simulations, which
are constructed to match with the observed multipole power spectra. We show
that the input cosmological parameters of the simulations can be recovered well
within the error bars by comparing the multipole power spectra of our
theoretical model and those of the mock subhalo catalogues. We also carefully
examine systematic uncertainties in our analysis by testing the dependence on
prior assumption of the theoretical model and the range of wavenumbers to be
used in the fitting. These investigations validate that the theoretical model
can be safely applied to the real data. Thus, our results from the SDSS DR7 LRG
sample are robust including systematics of theoretical modeling; f(z = 0.3)
sigma_8(z = 0.3) =0.49+-0.08(stat.)+-0.04(sys.), D_A (z = 0.3)
=968+-42(stat.)+-17(sys.)[Mpc], H (z = 0.3)
=81.7+-5.0(stat.)+-3.7(sys.)[km/s/Mpc]. We believe that our method to constrain
the cosmological parameters using subhaloes catalogues will be useful for more
refined samples like CMASS and LOWZ catalogues in the Baryon Oscillation
Spectroscopic Survey in SDSS-III.Comment: accepted for publication in MNRA
Crust and Upper Mantle Structure in Northeastern Japan Derived from the Velocity and Azimuth Anomalies Observed at the Kitakami Seismic Array
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