24,783 research outputs found
Polar codes and polar lattices for the Heegard-Berger problem
Explicit coding schemes are proposed to achieve the rate-distortion function of the Heegard-Berger problem using polar codes. Specifically, a nested polar code construction is employed to achieve the rate-distortion function for doublysymmetric binary sources when the side information may be absent. The nested structure contains two optimal polar codes for lossy source coding and channel coding, respectively. Moreover, a similar nested polar lattice construction is employed when the source and the side information are jointly Gaussian. The proposed polar lattice is constructed by nesting a quantization polar lattice and a capacity-achieving polar lattice for the additive white Gaussian noise channel
A least-squares implicit RBF-FD closest point method and applications to PDEs on moving surfaces
The closest point method (Ruuth and Merriman, J. Comput. Phys.
227(3):1943-1961, [2008]) is an embedding method developed to solve a variety
of partial differential equations (PDEs) on smooth surfaces, using a closest
point representation of the surface and standard Cartesian grid methods in the
embedding space. Recently, a closest point method with explicit time-stepping
was proposed that uses finite differences derived from radial basis functions
(RBF-FD). Here, we propose a least-squares implicit formulation of the closest
point method to impose the constant-along-normal extension of the solution on
the surface into the embedding space. Our proposed method is particularly
flexible with respect to the choice of the computational grid in the embedding
space. In particular, we may compute over a computational tube that contains
problematic nodes. This fact enables us to combine the proposed method with the
grid based particle method (Leung and Zhao, J. Comput. Phys. 228(8):2993-3024,
[2009]) to obtain a numerical method for approximating PDEs on moving surfaces.
We present a number of examples to illustrate the numerical convergence
properties of our proposed method. Experiments for advection-diffusion
equations and Cahn-Hilliard equations that are strongly coupled to the velocity
of the surface are also presented
Fluorescent probes of the orientation of myosin regulatory light chains in relaxed, rigor, and contracting muscle.
The orientation of the light-chain region of myosin heads in relaxed, rigor, and isometrically contracting fibers from rabbit psoas muscle was studied by fluorescence polarization. Cysteine 108 of chicken gizzard myosin regulatory light chain (cgRLC) was covalently modified with iodoacetamidotetramethylrhodamine (iodo-ATR). Native RLC of single glycerinated muscle fibers was exchanged for labeled cgRLC in a low [Mg2+] rigor solution at 30 degrees C. Troponin and troponin C removed in this procedure were replaced. RLC exchange had little effect on active force production. X-ray diffraction showed normal structure in rigor after RLC exchange, but loss of axial and helical order in relaxation. In isolated myofibrils labeled cgRLC was confined to the regions of the sarcomere containing myosin heads. The ATR dipoles showed a preference for orientations perpendicular to the fiber axis, combined with limited nanosecond rotational motion, in all conditions studied. The perpendicular orientation preference was more marked in rigor than in either relaxation or active contraction. Stretching relaxed fibers to sarcomere length 4 microns to eliminate overlap between actin- and myosin-containing filaments had little effect on the orientation preference. There was no change in orientation preference when fibers were put into rigor at sarcomere length 4.0 microns. Qualitatively similar results were obtained with ATR-labeled rabbit skeletal RLC
Continuous production of glycerol by catalytic high pressure hydrogenolysis of sucrose
Several continuous reactor systems have been discussed for the catalytic high pressure hydrogenolysis of sucrose to glycerol. Theoretically and actually, continuous reactors lead to lower glycerol yields than in a batch process. Two continuous stirred tank reactors in cascade constitute a reasonable compromise. An economic evaluation of the sucrose route to glycerol in comparison with other synthetic glycerol processes based on allyl chloride and acrolein suggests that the sucrose process can be competitive if a sales potential is developed for the by-products propane-l,2-diol, ethylene glycol, and a mixture of higher polyhydric alcohols containing tetritol, pentitol, methyl fructoside, and hexitol
Optimal Memoryless Encoding for Low Power Off-Chip Data Buses
Off-chip buses account for a significant portion of the total system power
consumed in embedded systems. Bus encoding schemes have been proposed to
minimize power dissipation, but none has been demonstrated to be optimal with
respect to any measure. In this paper, we give the first provably optimal and
explicit (polynomial-time constructible) families of memoryless codes for
minimizing bit transitions in off-chip buses. Our results imply that having
access to a clock does not make a memoryless encoding scheme that minimizes bit
transitions more powerful.Comment: Proceedings of the 2006 IEEE/ACM international Conference on
Computer-Aided Design (San Jose, California, November 05 - 09, 2006). ICCAD
'06. ACM, New York, NY, 369-37
Detecting Full N-Particle Entanglement in Arbitrarily High-Dimensional Systems with Bell-Type Inequality
We derive a set of Bell-type inequalities for arbitrarily high-dimensional
systems, based on the assumption of partial separability in the hybrid
local-nonlocal hidden variable model. Partially entangled states would not
violate the inequalities, and thus upon violation, these Bell-type inequalities
are sufficient conditions to detect the full -particle entanglement and
validity of the hybrid local-nonlocal hidden variable description.Comment: 6 page
BATSE Soft Gamma-Ray Observations of GROJ0422+32
We report results of a comprehensive study of the soft gamma-ray (30 keV to
1.7 MeV) emission of GROJ0422+32 during its first known outburst in 1992. These
results were derived from the BATSE earth-occultation database with the JPL
data analysis package, EBOP (Enhanced BATSE Occultation Package). Results
presented here focus primarily on the long-term temporal and spectral
variability of the source emission associated with the outburst. The light
curves with 1-day resolution in six broad energy-bands show the high-energy
flux (>200 keV) led the low-energy flux (<200 keV) by ~5 days in reaching the
primary peak, but lagged the latter by ~7 days in starting the declining phase.
We confirm the "secondary maximum" of the low-energy (<200 keV) flux at TJD
8970-8981, ~120 days after the first maximum. Our data show that the "secondary
maximum" was also prominent in the 200-300 keV band, but became less pronounced
at higher energies. During this 200-day period, the spectrum evolved from a
power-law with photon index of 1.75 on TJD 8839, to a shape that can be
described by a Comptonized model or an exponential power law below 300 keV,
with a variable power-law tail above 300 keV. The spectrum remained roughly in
this two-component shape until ~9 November (TJD 8935) and then returned to the
initial power-law shape with an index of ~2 until the end of the period. The
correlation of the two spectral shapes with the high and low luminosities of
the soft gamma-ray emission is strongly reminiscent of that seen in Cygnus X-1.
We interpret these results in terms of the Advection Dominated Accretion Flow
(ADAF) model with possibly a "jet-like" region that persistently produced the
non-thermal power-law gamma rays observed throughout the event.Comment: 40 pages total, including 10 figures and 2 table
- …