49,538 research outputs found
Metric adjusted skew information: Convexity and restricted forms of superadditivity
We give a truly elementary proof of the convexity of metric adjusted skew
information following an idea of Effros. We extend earlier results of weak
forms of superadditivity to general metric adjusted skew informations.
Recently, Luo and Zhang introduced the notion of semi-quantum states on a
bipartite system and proved superadditivity of the Wigner-Yanase-Dyson skew
informations for such states. We extend this result to general metric adjusted
skew informations. We finally show that a recently introduced extension to
parameter values of the WYD-information is a special case of
(unbounded) metric adjusted skew information.Comment: An error in the literature is pointed ou
Co- and counter-helicity interaction between two adjacent laboratory prominences
The interaction between two side-by-side solar prominence-like plasmas has been studied using a four-electrode magnetized plasma source that can impose a wide variety of surface boundary conditions. When the source is arranged to create two prominences with the same helicity (co-helicity), it is observed that helicity transfer from one prominence to the other causes the receiving prominence to erupt sooner and faster than the transmitting prominence. When the source is arranged to create two prominences with opposite helicity (counter-helicity), it is observed that upon merging, prominences wrap around each other to form closely spaced, writhing turns of plasma. This is followed by appearance of a distinct bright region in the middle and order of magnitude higher emission of soft x rays. The four-electrode device has also been used to change the angle of the neutral line and so form more pronounced S-shapes
Chain Reduction for Binary and Zero-Suppressed Decision Diagrams
Chain reduction enables reduced ordered binary decision diagrams (BDDs) and
zero-suppressed binary decision diagrams (ZDDs) to each take advantage of the
others' ability to symbolically represent Boolean functions in compact form.
For any Boolean function, its chain-reduced ZDD (CZDD) representation will be
no larger than its ZDD representation, and at most twice the size of its BDD
representation. The chain-reduced BDD (CBDD) of a function will be no larger
than its BDD representation, and at most three times the size of its CZDD
representation. Extensions to the standard algorithms for operating on BDDs and
ZDDs enable them to operate on the chain-reduced versions. Experimental
evaluations on representative benchmarks for encoding word lists, solving
combinatorial problems, and operating on digital circuits indicate that chain
reduction can provide significant benefits in terms of both memory and
execution time
The Jahn-Teller active fluoroperovskites : thermo- and magneto optical correlations as function of the -site
Chromium (II) fluoroperovskites are
strongly correlated Jahn-Teller active materials at low temperatures. In this
paper, we examine the role that the -site ion plays in this family of
fluoroperovskites using both experimental methods (XRD, optical absorption
spectroscopy and magnetic fields) and DFT simulations. Temperature-dependent
optical absorption experiments show that the spin-allowed transitions and
only merge completely for = Na at 2 K. Field-dependent optical
absorption measurements at 2 K show that the oscillating strength of the
spin-allowed transitions in increases with increasing
applied field. Direct magneto-structural correlations which suppress the
spin-flip transitions are observed for below its Ne\'el
temperature. In the spin-flip transitions vanish abruptly below
9 K revealing magneto-optical correlations not linked to crystal structure
changes. This suggests that as the long range ordering is reduced local JT
effects in the individual octahedra take control of the
observed behavior. Our results show clear deviation from the pattern found for
the isoelectronic system. The size of the -site cation
is shown to be central in dictating the physical properties and phase
transitions in , opening up the possibility of varying the
composition to create novel states of matter with tuneable properties
Bernstein-Szego Polynomials Associated with Root Systems
We introduce multivariate generalizations of the Bernstein-Szego polynomials,
which are associated to the root systems of the complex simple Lie algebras.
The multivariate polynomials in question generalize Macdonald's Hall-Littlewood
polynomials associated with root systems. For the root system of type A1
(corresponding to the Lie algebra SL (2;C)) the classic Bernstein-Szego
polynomials are recovered.Comment: LaTeX, 12 page
Classical Strongly Coupled QGP: VII. Shear Viscosity and Self Diffusion
We construct the Liouville operator for the SU(2) classical colored Coulomb
plasma (cQGP) for arbitrary values of the Coulomb coupling , the
ratio of the mean Coulomb to kinetic energy. We show that its resolvent in the
classical colored phase space obeys a hierarchy of equations. We use a free
streaming approximation to close the hierarchy and derive an integral equation
for the time-dependent structure factor. Its reduction by projection yields
hydrodynamical equations in the long-wavelength limit. We discuss the character
of the hydrodynamical modes at strong coupling. The shear viscosity is shown to
exhibit a minimum at near the liquid point. This minimum
follows from the cross-over between the single particle collisional regime
which drops as and the hydrodynamical collisional regime which
rises as . The self-diffusion constant drops as
irrespective of the regime. We compare our results to molecular dynamics
simulations of the SU(2) colored Coulomb plasma. We also discuss the relevance
of our results for the quantum and strongly coupled quark gluon plasma (sQGP)Comment: 36 pages, 14 figure
Toward the Jamming Threshold of Sphere Packings: Tunneled Crystals
We have discovered a new family of three-dimensional crystal sphere packings
that are strictly jammed (i.e., mechanically stable) and yet possess an
anomalously low density. This family constitutes an uncountably infinite number
of crystal packings that are subpackings of the densest crystal packings and
are characterized by a high concentration of self-avoiding "tunnels" (chains of
vacancies) that permeate the structures. The fundamental geometric
characteristics of these tunneled crystals command interest in their own right
and are described here in some detail. These include the lattice vectors (that
specify the packing configurations), coordination structure, Voronoi cells, and
density fluctuations. The tunneled crystals are not only candidate structures
for achieving the jamming threshold (lowest-density rigid packing), but may
have substantially broader significance for condensed matter physics and
materials science.Comment: 19 pages, 5 figure
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