title:
Vortical and Wave Modes in 3D Rotating Stratified Flows: Random Large
  Scale Forcing

abstract:
  Utilizing an eigenfunction decomposition, we study the growth and spectra of
energy in the vortical and wave modes of a 3D rotating stratified fluid as a
function of $\epsilon = f/N$. Working in regimes characterized by moderate
Burger numbers, i.e. $Bu = 1/\epsilon^2 < 1$ or $Bu \ge 1$, our results
indicate profound change in the character of vortical and wave mode
interactions with respect to $Bu = 1$. As with the reference state of
$\epsilon=1$, for $\epsilon < 1$ the wave mode energy saturates quite quickly
and the ensuing forward cascade continues to act as an efficient means of
dissipating ageostrophic energy. Further, these saturated spectra steepen as
$\epsilon$ decreases: we see a shift from $k^{-1}$ to $k^{-5/3}$ scaling for
$k_f < k < k_d$ (where $k_f$ and $k_d$ are the forcing and dissipation scales,
respectively). On the other hand, when $\epsilon > 1$ the wave mode energy
never saturates and comes to dominate the total energy in the system. In fact,
in a sense the wave modes behave in an asymmetric manner about $\epsilon = 1$.
With regard to the vortical modes, for $\epsilon \le 1$, the signatures of 3D
quasigeostrophy are clearly evident. Specifically, we see a $k^{-3}$ scaling
for $k_f < k < k_d$ and, in accord with an inverse transfer of energy, the
vortical mode energy never saturates but rather increases for all $k < k_f$. In
contrast, for $\epsilon > 1$ and increasing, the vortical modes contain a
progressively smaller fraction of the total energy indicating that the 3D
quasigeostrophic subsystem plays an energetically smaller role in the overall
dynamics.


title:
GRB 050315: A step toward the uniqueness of the overall GRB structure
  and the true nature of long GRBs

abstract:
  Using the Swift data of GRB 050315, we progress on the uniqueness of our
theoretically predicted Gamma-Ray Burst (GRB) structure as composed by a
proper-GRB (P-GRB), emitted at the transparency of an electron-positron plasma
with suitable baryon loading, and an afterglow comprising the so called "prompt
emission" as due to external shocks. Thanks to the Swift observations, we can
theoretically fit detailed light curves for selected energy bands on a
continuous time scale ranging over 10^6 seconds. The theoretically predicted
instantaneous spectral distribution over the entire afterglow confirms a clear
hard-to-soft behavior encompassing, continuously, the "prompt emission" all the
way to the latest phases of the afterglow. Consequences of the instrumental
threshold on the definition of "short" and "long" GRBs are discussed.


title:
Non Gaussianity and Non Stationarity modeled through Hidden Variables
  and their use in ICA and Blind Source Separation

abstract:
  Modeling non Gaussian and non stationary signals and images has always been
one of the most important part of signal and image processing methods. In this
paper, first we propose a few new models, all based on using hidden variables
for modeling either stationary but non Gaussian or Gaussian but non stationary
or non Gaussian and non stationary signals and images. Then, we will see how to
use these models in independent component analysis (ICA) or blind source
separation (BSS). The computational aspects of the Bayesian estimation
framework associated with these prior models are also discussed.


title:
Dynamos and anti-dynamos as thin magnetic flux ropes in Riemannian
  spaces

abstract:
  Two examples of magnetic anti-dynamos in magnetohydrodynamics (MHD) are
given. The first is a 3D metric conformally related to Arnold cat fast dynamo
metric: ${ds_{A}}^{2}=e^{-{\lambda}z}dp^{2}+e^{{\lambda}z}dq^{2}+dz^{2}$ is
shown to present a behaviour of non-dynamos where the magnetic field
exponentially decay in time. The curvature decay as z-coordinates increases
without bounds. Some of the Riemann curvature components such as $R_{pzpz}$
also undergoes dissipation while component $R_{qzqz}$ increases without bounds.
The remaining curvature component $R_{pqpq}$ is constant on the torus surface.
The other anti-dynamo which may be useful in plasma astrophysics is the thin
magnetic flux rope or twisted magnetic thin flux tube which also behaves as
anti-dynamo since it also decays with time. This model is based on the
Riemannian metric of the magnetic twisted flux tube where the axis possesses
Frenet curvature and torsion. Since in this last example the Frenet torsion of
the axis of the rope is almost zero, or the possible dynamo is almost planar it
satisfies Zeldovich theorem which states that planar dynamos do not exist.
Changing in topology of this result may result on a real dynamo as discussed.


title: The role of GRB 031203 in clarifying the astrophysical GRB scenario

abstract:
  The luminosity and the spectral distribution of the afterglow of GRB 031203
have been presented within our theoretical framework, which envisages the GRB
structure as composed by a proper-GRB, emitted at the transparency of an
electron-positron plasma with suitable baryon loading, and an afterglow
comprising the "prompt emission" as due to external shocks. In addition to the
GRB emission, there appears to be a prolonged soft X-Ray emission lasting for
10^6-10^7 seconds followed by an exponential decay. This additional source has
been called by us URCA-3. It is urgent to establish if this component is
related to the GRB or to the Supernova (SN). In this second case, there are two
possibilities: either the interaction of the SN ejecta with the interstellar
medium or, possibly, the cooling of a young neutron star formed in the SN
2003lw process. The analogies and the differences between this triptych GRB
031203 / SN 2003lw / URCA-3 and the corresponding ones GRB 980425 / SN 1998bw /
URCA-1 and GRB 030329 / SN 2003dh / URCA-2, as well as GRB 060218 / SN 2006aj
are discussed.


title:
Analysis of Spitzer Spectra of Irradiated Planets: Evidence for Water
  Vapor?

abstract:
  Published mid infrared spectra of transiting planets HD 209458b and HD
189733b, obtained during secondary eclipse by the InfraRed Spectrograph (IRS)
aboard the Spitzer Space Telescope, are predominantly featureless. In
particular these flux ratio spectra do not exhibit an expected feature arising
from water vapor absorption short-ward of 10 um. Here we suggest that, in the
absence of flux variability, the spectral data for HD 189733b are inconsistent
with 8 um-photometry obtained with Spitzer's InfraRed Array Camera (IRAC),
perhaps an indication of problems with the challenging reduction of the IRS
spectra. The IRAC point, along with previously published secondary eclipse
photometry for HD 189733b, are in good agreement with a one-dimensional model
of HD 189733b that clearly shows absorption due to water vapor in the emergent
spectrum. We are not able to draw firm conclusions regarding the IRS data for
HD 209458b, but spectra predicted by 1D and 3D atmosphere models fit the data
adequately, without adjustment of the water abundance or reliance on cloud
opacity. We argue that the generally good agreement between model spectra and
IRS spectra of brown dwarfs with atmospheric temperatures similar to these
highly irradiated planets lends confidence in the modeling procedure.


title:
Accumulation horizons and period-adding in optically injected
  semiconductor lasers

abstract:
  We study the hierarchical structuring of islands of stable periodic
oscillations inside chaotic regions in phase diagrams of single-mode
semiconductor lasers with optical injection. Phase diagrams display remarkable
{\it accumulation horizons}: boundaries formed by the accumulation of infinite
cascades of self-similar islands of periodic solutions of ever-increasing
period. Each cascade follows a specific period-adding route. The riddling of
chaotic laser phases by such networks of periodic solutions may compromise
applications operating with chaotic signals such as e.g. secure communications.


title: Hierarchical Markovian models for hyperspectral image segmentation

abstract:
  Hyperspectral images can be represented either as a set of images or as a set
of spectra. Spectral classification and segmentation and data reduction are the
main problems in hyperspectral image analysis. In this paper we propose a
Bayesian estimation approach with an appropriate hiearchical model with hidden
markovian variables which gives the possibility to jointly do data reduction,
spectral classification and image segmentation. In the proposed model, the
desired independent components are piecewise homogeneous images which share the
same common hidden segmentation variable. Thus, the joint Bayesian estimation
of this hidden variable as well as the sources and the mixing matrix of the
source separation problem gives a solution for all the three problems of
dimensionality reduction, spectra classification and segmentation of
hyperspectral images. A few simulation results illustrate the performances of
the proposed method compared to other classical methods usually used in
hyperspectral image processing.


title: Noncolliding Brownian Motion and Determinantal Processes

abstract:
  A system of one-dimensional Brownian motions (BMs) conditioned never to
collide with each other is realized as (i) Dyson's BM model, which is a process
of eigenvalues of hermitian matrix-valued diffusion process in the Gaussian
unitary ensemble (GUE), and as (ii) the $h$-transform of absorbing BM in a Weyl
chamber, where the harmonic function $h$ is the product of differences of
variables (the Vandermonde determinant). The Karlin-McGregor formula gives
determinantal expression to the transition probability density of absorbing BM.
We show from the Karlin-McGregor formula, if the initial state is in the
eigenvalue distribution of GUE, the noncolliding BM is a determinantal process,
in the sense that any multitime correlation function is given by a determinant
specified by a matrix-kernel. By taking appropriate scaling limits, spatially
homogeneous and inhomogeneous infinite determinantal processes are derived. We
note that the determinantal processes related with noncolliding particle
systems have a feature in common such that the matrix-kernels are expressed
using spectral projections of appropriate effective Hamiltonians. On the common
structure of matrix-kernels, continuity of processes in time is proved and
general property of the determinantal processes is discussed.

categories: math.PR cond-mat.stat-mech hep-th math-ph math.MP nlin.SI


title: Bayesian Separation of Document Images with Hidden Markov Model

abstract:
  this paper we consider the problem of separating noisy instantaneous linear
mixtures of document images in the Bayesian framework. The source image is
modeled hierarchically by a latent labeling process representing the common
classifications of document objects among different color channels and the
intensity process of pixels given the class labels. A Potts Markov random field
is used to model regional regularity of the classification labels inside object
regions. Local dependency between neighboring pixels can also be accounted by
smoothness constraint on their intensities. Within the Bayesian approach, all
unknowns including the source, the classification, the mixing coefficients and
the distribution parameters of these variables are estimated from their
posterior laws. The corresponding Bayesian computations are done by MCMC
sampling algorithm. Results from experiments on synthetic and real image
mixtures are presented to illustrate the performance of the proposed method.


title:
$\Lambda$CDM cosmology: how much suppression of credible evidence, and
  does the model really lead its competitors, using all evidence?

abstract:
  Astronomy can never be a hard core physics discipline, because the Universe
offers no control experiment, i.e. with no independent checks it is bound to be
highly ambiguous and degenerate. Thus e.g. while superluminal motion can be
explained by Special Relativity. data on the former can never on their own be
used to establish the latter. This is why traditionally astrophysicists have
been content with (and proud of) their ability to use known physical laws and
processes established in the laboratory to explain celestial phenomena.
Cosmology is not even astrophysics: all the principal assumptions in this field
are unverified (or unverifiable) in the laboratory, and researchers are quite
comfortable with inventing unknowns to explain the unknown. How then could,
after fifty years of failed attempt in finding dark matter, the fields of dark
matter {\it and now} dark energy have become such lofty priorities in astronomy
funding, to the detriment of all other branches of astronomy? I demonstrate in
this article that while some of is based upon truth, at least just as much of
$\Lambda$CDM cosmology has been propped by a paralyzing amount of propaganda
which suppress counter evidence and subdue competing models. The recent WMAP3
paper of Spergel et al (2007) will be used as case in point on selective
citation. I also show that when all evidence are taken into account, two of the
competing models that abolish dark energy and/or dark matter do not trail
behind $\Lambda$CDM by much. Given all of the above, I believe astronomy is no
longer heading towards a healthy future, unless funding agencies re-think their
master plans by backing away from such high a emphasis on groping in the dark.


title:
Collective diffusion coefficient of proteins with hydrodynamic,
  electrostatic and adhesive interactions

abstract:
  A theory is presented for lambda_C, the coefficient of the first-order
correction in the density of the collective diffusion coefficient, for protein
spheres interacting by electrostatic and adhesive forces. An extensive
numerical analysis of the Stokesian hydrodynamics of two moving spheres is
given so as to gauge the precise impact of lubrication forces. An effective
stickiness is introduced and a simple formula for lambda_C in terms of this
variable is put forward. A precise though more elaborate approximation for
lambda_C is also developed. These and numerically exact expressions for
lambda_C are compared with experimental data on lysozyme at pH 4.5 and a range
of ionic strengths between 0.05 M and 2 M.


title: Scaling Relations of Compressible MHD Turbulence

abstract:
  We study scaling relations of compressible strongly magnetized turbulence. We
find a good correspondence of our results with the Fleck (1996) model of
compressible hydrodynamic turbulence. In particular, we find that the
density-weighted velocity, i.e. $u \equiv \rho^{1/3} v$, proposed in Kritsuk et
al. (2007) obeys the Kolmogorov scaling, i.e. $E_{u}(k)\sim k^{-5/3}$ for the
high Mach number turbulence. Similarly, we find that the exponents of the third
order structure functions for $u$ stay equal to unity for the all the Mach
numbers studied. The scaling of higher order correlations obeys the She-Leveque
(1994) scalings corresponding to the two-dimensional dissipative structures,
and this result does not change with the Mach number either. In contrast to $v$
which exhibits different scaling parallel and perpendicular to the local
magnetic field, the scaling of $u$ is similar in both directions. In addition,
we find that the peaks of density create a hierarchy in which both physical and
column densities decrease with the scale in accordance to the Fleck (1996)
predictions. This hierarchy can be related ubiquitous small ionized and neutral
structures (SINS) in the interstellar gas. We believe that studies of
statistics of the column density peaks can provide both consistency check for
the turbulence velocity studies and insight into supersonic turbulence, when
the velocity information is not available.


title: The Real Solution to Scalar Field Equation in 5D Black String Space

abstract:
  After the nontrivial quantum parameters $\Omega_{n}$ and quantum potentials
$V_{n}$ obtained in our previous research, the circumstance of a real scalar
wave in the bulk is studied with the similar method of Brevik (2001). The
equation of a massless scalar field is solved numerically under the boundary
conditions near the inner horizon $r_{e}$ and the outer horizon $r_{c}$. Unlike
the usual wave function $\Psi_{\omega l}$ in 4D, quantum number $n$ introduces
a new functions $\Psi_{\omega l n}$, whose potentials are higher and wider with
bigger n. Using the tangent approximation, a full boundary value problem about
the Schr$\ddot{o}$dinger-like equation is solved. With a convenient replacement
of the 5D continuous potential by square barrier, the reflection and
transmission coefficients are obtained. If extra dimension does exist and is
visible at the neighborhood of black holes, the unique wave function
$\Psi_{\omega l n}$ may say something to it.


title: Analysis of the Arrival Directions of Ultrahigh Energy Cosmic Rays

abstract:
  The arrival directions of ultrahigh energy extensive air showers (EAS) by
Yakutsk, AGASA and SUGAR array data are considered. For the first time, the
maps of equal exposition of celestial sphere for the distribution of particles
by AGASA and SUGAR array data have been constructed. The large-scale anisotropy
of E>4.10^19 eV cosmic rays from the side of Input and Output of the Galaxy
Local Arm by Yakutsk, AGASA and SUGAR array data has been detected. The problem
of cosmic ray origin is discussed.


title:
Vector-valued modular functions for the modular group and the
  hypergeometric equation

abstract:
  A general theory of vector-valued modular functions, holomorphic in the upper
half-plane, is presented for finite dimensional representations of the modular
group. This also provides a description of vector-valued modular forms of
arbitrary half-integer weight. It is shown that the space of these modular
functions is spanned, as a module over the polynomials in J, by the columns of
a matrix that satisfies an abstract hypergeometric equation, providing a simple
solution of the Riemann-Hilbert problem for representations of the modular
group. Restrictions on the coefficients of this differential equation implied
by analyticity are discussed, and an inversion formula is presented that allows
the determination of an arbitrary vector-valued modular function from its
singular behavior. Questions of rationality and positivity of expansion
coefficients are addressed. Closed expressions for the number of vector-valued
modular forms of half-integer weight are given, and the general theory is
illustrated on simple examples.


title: Heisenberg limited Sagnac interferometry

abstract:
  We show how the entangled photons produced in parametric down conversion can
be used to improve the sensitivity of a Sagnac interferometer. Two-photon and
four-photon coincidences increases the sensitivity by a factor of two and four
respectively. Our results apply to sources with arbitrary pumping and squeezing
parameters.


title:
Ricci Flat Black Holes and Hawking-Page Phase Transition in Gauss-Bonnet
  Gravity and Dilaton Gravity

abstract:
  It is well-known that there exists a Hawking-Page phase transition between a
spherical AdS black hole and a thermal AdS space. The phase transition does not
happen between a Ricci flat AdS black hole whose horizon is a Ricci flat space
and a thermal AdS space in the Poincare coordinates. However, the Hawking-Page
phase transition occurs between a Ricci flat AdS black hole and an AdS soliton
if at least one of horizon coordinates for the Ricci flat black hole is
compact. We show a similar phase transition betwen the Ricci flat black holes
and deformed AdS solitons in the Gauss-Bonnet gravity and the dilaton gravity
with a Liouville-type potential including the gauged supergravity coming from
the spherical reduction of Dp-branes in type II supergravity. In contrast to
Einstein gravity, we find that the high temperature phase can be dominated
either by black holes or deformed AdS solitons depending on parameters.


title: $Qq\bar Q\bar q'$ States in Chiral SU(3) Quark Model

abstract:
  In this work, we study the masses of $Qq\bar Q\bar q'$ states with
J^{PC}=0^{++}, 1^{++}, 1^{+-} and 2^{++} in the chiral SU(3) quark model, where
Q is the heavy quark (c or b) and q (q') is the light quark (u, d or s).
According to our numerical results, it is improbable to make the interpretation
of $[cn\bar c\bar n]_{1^{++}}$ and $[cn\bar c\bar n]_{2^{++}}$ (n=u, d) states
as X(3872) and Y(3940), respectively. However, it is interesting to find the
tetraquarks in the $bq\bar b\bar q'$ system.


title: Kappa-Minkowski space-time and the star product realizations

abstract:
  We investigate a Lie algebra-type $ \kappa$-deformed Minkowski space-time
with undeformed Lorentz algebra and mutually commutative vector-like Dirac
derivatives. There are infinitely many realizations of $ \kappa$-Minkowski
space. The coproduct and the star product corresponding to each of them are
found. Utilizing the properties of the {\em{natural}} realization, we construct
a scalar field theory on $ \kappa$-deformed Minkowski space and show that it is
equivalent to the scalar, nonlocal, relativistically invariant field theory on
the ordinary Minkowski space.


title: Non-Markovian decoherence dynamics of entangled coherent states

abstract:
  We microscopically model the decoherence dynamics of entangled coherent
states under the influence of vacuum fluctuation. We derive an exact master
equation with time-dependent coefficients reflecting the memory effect of the
environment, by using the Feynman-Vernon influence functional theory in the
coherent-state representation. Under the Markovian approximation, our master
equation recovers the widely used Lindblad equation in quantum optics. We then
investigate the non-Markovian entanglement dynamics of the quantum channel in
terms of the entangled coherent states under noise. Compared with the results
in Markovian limit, it shows that the non-Markovian effect enhances the
disentanglement to the initially entangled coherent state. Our analysis also
shows that the decoherence behaviors of the entangled coherent states depend
sensitively on the symmetrical properties of the entangled coherent states as
well as the interactions between the system and the environment.


title:
Thermodynamics of the Up-Up-Down Phase of the S = 1/2 Triangular-Lattice
  Antiferromagnet Cs$_2$CuBr$_4$

abstract:
  Specific heat and the magnetocaloric effect are used to probe the
field-induced up-up-down phase of Cs2CuBr4, a quasi-two-dimensional spin-1/2
triangular antiferromagnet with near-maximal frustration. The shape of the
magnetic phase diagram shows that the phase is stabilized by quantum
fluctuations, not by thermal fluctuations as in the corresponding phase of
classical spins. The magnon gaps determined from the specific heat are
considerably larger than those expected for a Heisenberg antiferromagnet,
probably due to the presence of a small Dzyaloshinskii-Moriya interaction.


title: The Nonperiodic Anyon Model and the Fractional Quantum Hall Effect

abstract:
  The lowest-Landau-level anyon model becomes nonperiodic in the statistics
parameter when the finite size of the attached flux tubes is taken into
account. The finite-size effects cause the inverse proportional relation
between the critical filling factor and the statistics parameter to be
nonperiodically continued in the screening regime, where the fluxes are
anti-parallel to the external magnetic field -- at critical filling, the
external magnetic field is entirely screened by the mean magnetic field
associated with the flux tubes. A clustering argument is proposed to select
particular values of the statistics parameter. In this way, IQHE and FQHE
fillings are obtained in terms of gapped nondegenerate LLL-anyonic wave
functions. Jain's series are reproduced without the need to populate higher
Landau levels. New FQHE series are proposed, like, in particular, the
particle-hole complementary series of the Laughlin one. For fast-rotating
Bose-Einstein condensates, a corresponding clustering argument yields
particular fractional filling series.


title:
Noise-Induced Synchronization and Clustering in Ensembles of Uncoupled
  Limit-Cycle Oscillators

abstract:
  We study synchronization properties of general uncoupled limit-cycle
oscillators driven by common and independent Gaussian white noises. Using phase
reduction and averaging methods, we analytically derive the stationary
distribution of the phase difference between oscillators for weak noise
intensity. We demonstrate that in addition to synchronization, clustering, or
more generally coherence, always results from arbitrary initial conditions,
irrespective of the details of the oscillators.


title:
Topological Discrete Algebra, Ground State Degeneracy, and Quark
  Confinement in QCD

abstract:
  Based on the permutation group formalism, we present a discrete symmetry
algebra in QCD. The discrete algebra is hidden symmetry in QCD, which is
manifest only on a space-manifold with non-trivial topology. Quark confinement
in the presence of the dynamical quarks is discussed in terms of the discrete
symmetry algebra. It is shown that the quark deconfinement phase has the ground
state degeneracy depending on the topology of the space, which gives a
gauge-invariant distinction between the confinement and deconfinement phases.
We also point out that new quantum numbers relating to the fractional quantum
Hall effect exist in the deconfinement phase.


title: Ces\`aro means of orthogonal expansions in several variables

abstract:
  Ces\`aro $(C,\delta)$ means are studied for orthogonal expansions with
respect to the weight function $\prod_{i=1}^{d}|x_i|^{2\k_i}$ on the unit
sphere, and for the corresponding weight functions on the unit ball and the
Jacobi weight on the simplex. A sharp pointwise estimate is established for the
$(C,\d)$ kernel with $\d > -1$ and for the kernel of the projection operator,
which allows us to derive the exact order for the norm of the
  Ces\`aro means and the projection operator on these domains.


title: Entropy of an extremal regular black hole

abstract:
  We introduce a magnetically charged extremal regular black hole in the
coupled system of Einstein gravity and nonlinear electrodynamics. Its near
horizon geometry is given by $AdS_2\times S^2$. It turns out that the entropy
function approach does not automatically lead to a correct entropy of the
Bekenstein-Hawking entropy. This contrasts to the case of the extremal
Reissner-Norstr\"om black hole in the Einstein-Maxwell theory. We conclude that
the entropy function approach does not work for a magnetically charged extremal
regular black hole without singularity, because of the nonlinearity of the
entropy function.


title:
General solution of overdamped Josephson junction equation in the case
  of phase-lock

abstract:
  The first order nonlinear ODE d phi(t)/d t + sin phi(t)=B+A cos(omega t),
(A,B,omega are real constants) is investigated. Its general solution is derived
in the case of the choice of parameters ensuring the phase-lock mode. It is
represented in terms of Floquet solution of double confluent Heun equation.


title:
Recursive calculation of effective resistances in distance-regular
  networks based on Bose-Mesner algebra and Christoffel-Darboux identity

abstract:
  Recently in \cite{jss1}, the authors have given a method for calculation of
the effective resistance (resistance distance) on distance-regular networks,
where the calculation was based on stratification introduced in \cite{js} and
Stieltjes transform of the spectral distribution (Stieltjes function)
associated with the network. Also, in Ref. \cite{jss1} it has been shown that
the resistance distances between a node $\alpha$ and all nodes $\beta$
belonging to the same stratum with respect to the $\alpha$
($R_{\alpha\beta^{(i)}}$, $\beta$ belonging to the $i$-th stratum with respect
to the $\alpha$) are the same. In this work, an algorithm for recursive
calculation of the resistance distances in an arbitrary distance-regular
resistor network is provided, where the derivation of the algorithm is based on
the Bose-Mesner algebra, stratification of the network, spectral techniques and
Christoffel-Darboux identity. It is shown that the effective resistance on a
distance-regular network is an strictly increasing function of the shortest
path distance defined on the network. In the other words, the two-point
resistance $R_{\alpha\beta^{(m+1)}}$ is strictly larger than
$R_{\alpha\beta^{(m)}}$. The link between the resistance distance and random
walks on distance-regular networks is discussed, where the average commute time
(CT) and its square root (called Euclidean commute time (ECT)) as a distance
are related to the effective resistance. Finally, for some important examples
of finite distance- regular networks, the resistance distances are calculated.
  {\bf Keywords: resistance distance, association scheme, stratification,
distance-regular networks, Christoffel-Darboux identity}
  {\bf PACs Index: 01.55.+b, 02.10.Yn}


title:
Single Longitudinal-Spin Asymmetries in Lepton-Pair Production at RHIC
  and J-PARC

abstract:
  We study the single longitudinal-spin asymmetries in lepton-pair production
with large transverse-momentum at RHIC and J-PARC experiments. The asymmetries
in the azimuthal angular distribution of a lepton can arise from an absorptive
part of production amplitudes. We revisit the one-loop calculation for the
absorptive part of production amplitudes in perturbative QCD, and show that the
asymmetries can be sizable at RHIC and J-PARC. Measurement of the asymmetries
would test the one-loop prediction for the scattering phase of this process,
and provide support for a study of the single transverse-spin asymmetries in
the same kinematical region.


title:
Lasing from single, stationary, dye-doped glycerol/water microdroplets
  located on a superhydrophobic surface

abstract:
  We report laser emission from single, stationary, Rhodamine B-doped
glycerol/water microdroplets located on a superhydrophobic surface. In the
experiments, a pulsed, frequency-doubled Nd:YAG laser operating at 532 nm was
used as the excitation source. The microdroplets ranged in diameter from a few
to 20 um. Lasing was achieved in the red-shifted portion of the dye emission
spectrum with threshold fluences as low as 750 J/cm2. Photobleaching was
observed when the microdroplets were pumped above threshold. In certain cases,
multimode lasing was also observed and attributed to the simultaneous lasing of
two modes belonging to different sets of whispering gallery modes.


title: A Spectral Sequence for the K-theory of Tiling Spaces

abstract:
  Let $\Tt$ be an aperiodic and repetitive tiling of $\RM^d$ with finite local
complexity. We present a spectral sequence that converges to the $K$-theory of
$\Tt$ with $E_2$-page given by a new cohomology that will be called PV in
reference to the Pimsner-Voiculescu exact sequence. It is a generalization of
the Serre spectral sequence. The PV cohomology of $\Tt$ generalizes the
cohomology of the base space of a fibration with local coefficients in the
$K$-theory of its fiber. We prove that it is isomorphic to the \v{C}ech
cohomology of the hull of $\Tt$ (a compactification of the family of its
translates).


title:
Diagnostics of the Synchronization of Self-Oscillatory Systems by an
  External Force with Varying Frequency with the Use of Wavelet Analysis

abstract:
  A diagnostics method based on a continuous wavelet transform is proposed.
This method makes it possible to diagnose the presence of synchronization of
the oscillations of a self-excited oscillator locked by an external force with
a linearly modulated frequency and to distinguish such a situation from the
case when an external signal leaks into self-oscillations; i.e., the signals
are summed without a change in the self-oscillation frequency. The method's
efficiency is shown with the use of a Van der Pol generator and experimental
physiological data as examples.


title:
Using Genetic Algorithms to Optimise Rough Set Partition Sizes for HIV
  Data Analysis

abstract:
  In this paper, we present a method to optimise rough set partition sizes, to
which rule extraction is performed on HIV data. The genetic algorithm
optimisation technique is used to determine the partition sizes of a rough set
in order to maximise the rough sets prediction accuracy. The proposed method is
tested on a set of demographic properties of individuals obtained from the
South African antenatal survey. Six demographic variables were used in the
analysis, these variables are; race, age of mother, education, gravidity,
parity, and age of father, with the outcome or decision being either HIV
positive or negative. Rough set theory is chosen based on the fact that it is
easy to interpret the extracted rules. The prediction accuracy of equal width
bin partitioning is 57.7% while the accuracy achieved after optimising the
partitions is 72.8%. Several other methods have been used to analyse the HIV
data and their results are stated and compared to that of rough set theory
(RST).


title: Quantization of soliton systems and Langlands duality

abstract:
  We consider the problem of quantization of classical soliton integrable
systems, such as the KdV hierarchy, in the framework of a general formalism of
Gaudin models associated to affine Kac--Moody algebras. Our experience with the
Gaudin models associated to finite-dimensional simple Lie algebras suggests
that the common eigenvalues of the mutually commuting quantum Hamiltonians in a
model associated to an affine algebra should be encoded by affine opers
associated to the Langlands dual affine algebra. This leads us to some concrete
predictions for the spectra of the quantum Hamiltonians of the soliton systems.
In particular, for the KdV system the corresponding affine opers may be
expressed as Schroedinger operators with spectral parameter, and our
predictions in this case match those recently made by Bazhanov, Lukyanov and
Zamolodchikov. This suggests that this and other recently found examples of the
correspondence between quantum integrals of motion and differential operators
may be viewed as special cases of the Langlands duality.


title: A "hybrid plane" with spin-orbit interaction

abstract:
  In this paper we attempt to reconstruct one of the last projects of Volodya
Geyler which remained unfinished. We study motion of a quantum particle in the
plane to which a halfline lead is attached assuming that the particle has spin
$\frac12$ and the plane component of the Hamiltonian contains a spin-orbit
interaction of either Rashba or Dresselhaus type. We construct the class of
admissible Hamiltonians and derive an explicit expression for the Green
function applying it to the scattering in such a system.

categories: math-ph cond-mat.mes-hall math.MP math.SP quant-ph


title: On dynamics of velocity vector potential in incompressible fluids

abstract:
  An elegant quaternionic formulation is given for the Lagrangian advection
equation for velocity vector potential in fluid dynamics. At first we study the
topological significance of a restricted conserved quantity viz.,
stream-helicity and later more realistic configuration of open streamlines is
figured out. Also, using Clebsch parameterisation of the velocity vector
potential yet another physical significance for the stream-helicity is
provided. Finally we give a Nambu-Poisson formalism of the Lagrangian advection
equation for velocity vector potential.


title:
Characterization of rank two locally nilpotent derivations in dimension
  three

abstract:
  In this paper we give an algorithmic characterization of rank two locally
nilpotent derivations in dimension three. Together with an algorithm for
computing the plinth ideal, this gives a method for computing the rank of a
locally nilpotent derivation in dimension three.


title: Origin of matter out of pure curvature

abstract:
  We propose a mechanism for origin of matter in the universe in the framework
of Einstein-Gauss-Bonnet gravity in higher dimensions. The recently discovered
new static black hole solution by the authors \cite{md2006} with the
Kaluza-Klein split up of spacetime as a product of the usual ${\ma M}^4$ with a
space of negative constant curvature is indeed a pure gravitational creation of
a black hole which is also endowed with a Maxwell-like {\it gravitational
charge} in four-dimensional vacuum spacetime. Further it could be envisioned as
being formed from anti-de Sitter spacetime by collapse of radially inflowing
charged null dust. It thus establishes the remarkable reciprocity between
matter and gravity - as matter produces gravity (curvature), gravity too
produces matter.


title:
Sparse and Dense Encoding in Layered Associative Network of Spiking
  Neurons

abstract:
  A synfire chain is a simple neural network model which can propagate stable
synchronous spikes called a pulse packet and widely researched. However how
synfire chains coexist in one network remains to be elucidated. We have studied
the activity of a layered associative network of Leaky Integrate-and-Fire
neurons in which connection we embed memory patterns by the Hebbian Learning.
We analyzed their activity by the Fokker-Planck method. In our previous report,
when a half of neurons belongs to each memory pattern (memory pattern rate
$F=0.5$), the temporal profiles of the network activity is split into
temporally clustered groups called sublattices under certain input conditions.
In this study, we show that when the network is sparsely connected ($F<0.5$),
synchronous firings of the memory pattern are promoted. On the contrary, the
densely connected network ($F>0.5$) inhibit synchronous firings. The sparseness
and denseness also effect the basin of attraction and the storage capacity of
the embedded memory patterns. We show that the sparsely(densely) connected
networks enlarge(shrink) the basion of attraction and increase(decrease) the
storage capacity.


title: Triangulable locally nilpotent derivations in dimension three

abstract:
  In this paper we give an algorithm to recognize triangulable locally
nilpotent derivations in dimension three. In case the given derivation is
triangulable, our method produces a coordinate system in which it exhibits a
triangular form.


title:
Kaon semileptonic decay (K_{l3}) form factor in the nonlocal chiral
  quark model

abstract:
  We investigate the kaon semileptonic decay (K_{l3}) form factors within the
framework of the nonlocal chiral quark model from the instanton vacuum, taking
into account the effects of flavor SU(3) symmetry breaking. All theoretical
calculations are carried out without any adjustable parameter. We also show
that the present results satisfy the Callan-Treiman low-energy theorem as well
as the Ademollo-Gatto theorem. It turns out that the effects of flavor SU(3)
symmetry breaking are essential in reproducing the kaon semileptonic form
factors. The present results are in a good agreement with experiments, and are
compatible with other model calculations.


title:
Many-worlds interpretation of quantum theory and mesoscopic anthropic
  principle

abstract:
  We suggest to combine the Anthropic Principle with Many-Worlds Interpretation
of Quantum Theory. Realizing the multiplicity of worlds it provides an
opportunity of explanation of some important events which are assumed to be
extremely improbable. The Mesoscopic Anthropic Principle suggested here is
aimed to explain appearance of such events which are necessary for emergence of
Life and Mind. It is complementary to Cosmological Anthropic Principle
explaining the fine tuning of fundamental constants. We briefly discuss various
possible applications of Mesoscopic Anthropic Principle including the Solar
Eclipses and assembling of complex molecules. Besides, we address the problem
of Time's Arrow in the framework of Many-World Interpretation. We suggest the
recipe for disentangling of quantities defined by fundamental physical laws and
by an anthropic selection.


title: Deformations of generalized complex and generalized Kahler structures

abstract:
  In this paper we obtain a stability theorem of generalized Kahler structures
with one pure spinor under small deformations of generalized complex
structures. (This is analogous to the stability theorem of Kahler manifolds by
Kodaira-Spencer.) We apply the stability theorem to a class of compact Kahler
manifolds which admits deformations to generalized complex manifolds and obtain
non-trivial generalized Kahler structures on Fano surfaces and toric Kahler
manifolds. In particular, we show that holomorphic Poisson structures on a
Kahler manifold induce deformations of generalized Kahler structures.


title: Galactic dark matter as a bulk effect on the brane

abstract:
  The behavior of the angular velocity of a test particle moving in a stable
circular orbit in the vacuum on the brane is considered. In the brane world
scenario, the four dimensional effective Einstein equation acquire extra terms,
called dark radiation and dark pressure, respectively, which arise from the
embedding of the 3-brane in the bulk. A large number of independent
observations have shown that the rotational velocities of test particles
gravitating around galaxies tend, as a function of the distance from the
galactic center, toward constant values. By assuming a constant tangential
velocity, the general solution of the vacuum gravitational field equations on
the brane can be obtained in an exact analytic form. This allows us to obtain
the explicit form of the projections of the bulk Weyl tensor on the brane, and
the equation of state of the dark pressure as a function of the dark radiation.
The physical and geometrical quantities are expressed in terms of
observable/measurable parameters, like the tangential velocity, the baryonic
mass and the radius of the galaxy. We also analyze the dynamics of test
particles by using methods from the qualitative analysis of dynamical systems,
by assuming a simple linear equation of state for the dark pressure. The
obtained results provide a theoretical framework for the observational testing
at the extra-galactic scale of the predictions of the brane world models.


title:
Spatial Characteristics of Joint Application Networks in Japanese
  Patents

abstract:
  Technological innovation has extensively been studied to make firms
sustainable and more competitive. Within this context, the most important
recent issue has been the dynamics of collaborative innovation among firms. We
therefore investigated a patent network, especially focusing on its spatial
characteristics. The results can be summarized as follows. (1) The degree
distribution in a patent network follows a power law. A firm can then be
connected to many firms via hubs connected to the firm. (2) The neighbors'
average degree has a null correlation, but the clustering coefficient has a
negative correlation. The latter means that there is a hierarchical structure
and bridging different modules may shorten the paths between the nodes in them.
(3) The distance of links not only indicates the regional accumulations of
firms, but the importance of time it takes to travel, which plays a key role in
creating links. (4) The ratio of internal links in cities indicates that we
have to consider the existing links firms have to facilitate the creation of
new links.


title: Ferromagnetism in nanoscale BiFeO3

abstract:
  A remarkably high saturation magnetization of ~0.4mu_B/Fe along with room
temperature ferromagnetic hysteresis loop has been observed in nanoscale (4-40
nm) multiferroic BiFeO_3 which in bulk form exhibits weak magnetization
(~0.02mu_B/Fe) and an antiferromagnetic order. The magnetic hysteresis loops,
however, exhibit exchange bias as well as vertical asymmetry which could be
because of spin pinning at the boundaries between ferromagnetic and
antiferromagnetic domains. Interestingly, like in bulk BiFeO_3, both the
calorimetric and dielectric permittivity data in nanoscale BiFeO_3 exhibit
characteristic features at the magnetic transition point. These features
establish formation of a true ferromagnetic-ferroelectric system with a
coupling between the respective order parameters in nanoscale BiFeO_3.


title: Nonclassical rotational inertia for a supersolid under rotation

abstract:
  As proposed by Leggett [4], the supersolidity of a crystal is characterized
by the Non Classical Rotational Inertia (NCRI) property. Using a model of
quantum crystal introduced by Josserand, Pomeau and Rica [5], we prove that
NCRI occurs. This is done by analyzing the ground state of the aforementioned
model, which is related to a sphere packing problem, and then deriving a
theoretical formula for the inertia momentum. We infer a lower estimate for the
NCRI fraction, which is a landmark of supersolidity.


title: Enhanced roughness of lipid membranes caused by external electric fields

abstract:
  The behavior of lipid membranes in the presence of an external electric field
is studied and used to examine the influence of such fields on membrane
parameters such as roughness and show that for a micro sized membrane,
roughness grows as the field increases. The dependence of bending rigidity on
the electric field is also studied and an estimation of thickness of the
accumulated charges around lipid membranes in a free-salt solution is
presented.


title: Non-Gaussianities in extended D-term inflation

abstract:
  We explore extensions of hybrid inflationary models in the context of
supersymmetric D-term inflation. We point out that a large variety of
inflationary scenarios can be encountered when the field content is extended.
It is not only possible to get curvaton type models but also scenarios in which
different fields, with nontrivial statistical properties, contribute to the
primordial curvature fluctuations. We explore more particularly the parameter
space of these multiple field inflationary models. It is shown that there
exists a large domain in which significant primordial non-Gaussianities can be
produced while preserving a scale free power spectrum for the metric
fluctuations. In particular we explicitly compute the expected bi- and
trispectrum for such models and compared the results to the current and
expected observational constraints. It is shown that it is necessary to use
both the bi- and tri-spectra of CMB anisotropies to efficiently reduce their
parameter space.


title:
WIMP identification through a combined measurement of axial and scalar
  couplings

abstract:
  We study the prospects for detecting Weakly Interacting Massive Particles
(WIMPs), in a number of phenomenological scenarios, with a detector composed of
a target simultaneously sensitive to both spin-dependent and spin-independent
couplings, as is the case of COUPP (Chicagoland Observatory for Underground
Particle Physics). First, we show that sensitivity to both couplings optimizes
chances of initial WIMP detection. Second, we demonstrate that in case of
detection, comparison of the signal on two complementary targets, such as in
COUPP CF3I and C4F10 bubble chambers, allows a significantly more precise
determination of the dark matter axial and scalar couplings. This strategy
would provide crucial information on the nature of the WIMPs, and possibly
allow discrimination between neutralino and Kaluza-Klein dark matter.


title: Improved Approximability Result for Test Set with Small Redundancy

abstract:
  Test set with redundancy is one of the focuses in recent bioinformatics
research. Set cover greedy algorithm (SGA for short) is a commonly used
algorithm for test set with redundancy. This paper proves that the
approximation ratio of SGA can be $(2-\frac{1}{2r})\ln n+{3/2}\ln r+O(\ln\ln
n)$ by using the potential function technique. This result is better than the
approximation ratio $2\ln n$ which directly derives from set multicover, when
$r=o(\frac{\ln n}{\ln\ln n})$, and is an extension of the approximability
results for plain test set.


title:
Nonlinear Relaxation Dynamics in Elastic Networks and Design Principles
  of Molecular Machines

abstract:
  Analyzing nonlinear conformational relaxation dynamics in elastic networks
corresponding to two classical motor proteins, we find that they respond by
well-defined internal mechanical motions to various initial deformations and
that these motions are robust against external perturbations. We show that this
behavior is not characteristic for random elastic networks. However, special
network architectures with such properties can be designed by evolutionary
optimization methods. Using them, an example of an artificial elastic network,
operating as a cyclic machine powered by ligand binding, is constructed.


title: The CoRoT primary target HD 52265: models and seismic tests

abstract:
  HD 52265 is the only known exoplanet-host star selected as a main target for
the seismology programme of the CoRoT satellite. As such, it will be observed
continuously during five months, which is of particular interest in the
framework of planetary systems studies. This star was misclassified as a giant
in the Bright Star Catalog, while it is more probably on the main-sequence or
at the beginning of the subgiant branch. We performed an extensive analysis of
this star, showing how asteroseismology may lead to a precise determination of
its external parameters and internal structure. We first reviewed the
observational constraints on the metallicity, the gravity and the effective
temperature derived from the spectroscopic observations of HD 52265. We also
derived its luminosity using the Hipparcos parallax. We computed the
evolutionary tracks for models of various metallicities which cross the
relevant observational error boxes in the gravity-effective temperature plane.
We selected eight different stellar models which satisfy the observational
constraints, computed their p-modes frequencies and analysed specific seismic
tests. The possible models for HD 52265, which satisfy the constraints derived
from the spectroscopic observations, are different in both their external and
internal parameters. They lie either on the main sequence or at the beginning
of the subgiant branch. The differences in the models lead to quite different
properties of their oscillation frequencies. We give evidences of an
interesting specific behaviour of these frequencies in case of helium-rich
cores: the ``small separations'' may become negative and give constraints on
the size of the core. We expect that the observations of this star by the CoRoT
satellite wi ll allow choosing between these possible models.


title: Odd-frequency pairing in normal metal/superconductor junctions

abstract:
  We study the induced odd-frequency pairing states in ballistic normal
metal/superconductor (N/S) junctions where a superconductor has even-frequency
symmetry in the bulk and a normal metal layer has an arbitrary length. Using
the quasiclassical Green's function formalism, we demonstrate that, quite
generally, the pair amplitude in the junction has an admixture of an
odd-frequency component due to the breakdown of translational invariance near
the N/S interface where the pair potential acquires spatial dependence. If a
superconductor has even-parity pair potential (spin-singlet s-wave state), the
odd-frequency pairing component with odd-parity is induced near the N/S
interface, while in the case of odd-parity pair potential (spin-triplet
$p_{x}$-wave or spin-singlet $d_{xy}$-wave) the odd-frequency component with
even-parity is generated. We show that in conventional s-wave junctions, the
amplitude of the odd-frequency pairing state is enhanced at energies
corresponding to the peaks in the local density of states (LDOS). In $p_x$- and
$d_{xy}$-wave junctions, the amplitude of the odd-frequency component on the S
side of the N/S interface is enhanced at zero energy where the midgap Andreev
resonant state (MARS) appears due to the sign change of the pair potential. The
odd-frequency component extends into the N region and exceeds the
even-frequency component at energies corresponding to the LDOS peak positions,
including the MARS.


title:
The velocity structure of moving magnetic feature pairs around sunspots:
  support for the U-loop model

abstract:
  Using data recorded by the Michelson Doppler Imager (MDI) instrument on the
Solar and Heliospheric Observatory (SOHO), we have traced 123 pairs of opposite
magnetic polarity moving magnetic features (MMFs) in three active regions NOAA
ARs 8375, 0330 and 9575. At the time of observation, AR 8375 was young, AR 0330
mature, and AR 9575 decaying. The vertical velocity indicates that the elements
of MMF pairs with polarity opposite to that of the sunspot support a downflow
of around 50-100 m s$^{-1}$. The average Doppler shift difference between
negative and positive elements of an MMF pair is about 150 m s$^{-1}$ in AR
8375, 100 m s$^{-1}$ in AR 0330, and 20 m s$^{-1}$ in AR 9575. These
observational results are in agreement with the model that MMF pairs are part
of a U-loop emanating from the sunspot's magnetic canopy. According to this
model the downflow is caused by the Evershed flow returning below the solar
surface. For AR 8375, the horizontal velocity of MMFs ranges from 0.1 km
s$^{-1}$ to 0.7 km s$^{-1}$, and on average, the velocity of an MMF pair
decreases significantly (from 0.6 km s$^{-1}$ to 0.35 km s$^{-1}$) with
increasing distance from the MMF's birth place. This result suggests that the
change in MMF flow speed does not reflect the radial structure of the moat
flow, but rather is intrinsic to the evolution of the MMF pairs. This result is
also in agreement with the U-loop model of MMF pairs. We also find that
properties of MMF pairs, most strikingly the lifetime, depend on the evolution
stages of the parent sunspot. The mean lifetimes of MMF pairs in ARs 9575 and
0330 are 0.7 hours and 1.6 hours, respectively, which is considerably shorter
than the 4 hours lifetime previously found for AR 8375.


title:
Theorie des longitudinalen Atomstrahl-Spinechos und paritaetsverletzende
  Berry-Phasen in Atomen

abstract:
  We present a nonrelativistic theory for the quantum mechanical description of
longitudinal atomic beam spin echo experiments, where a beam of neutral atoms
is subjected to static electric and magnetic fields. The atomic wave function
is the solution of a matrix-valued Schroedinger equation and can be written as
superposition of local (atomic) eigenstates of the potential matrix. The
position- and time-dependent amplitude function of each eigenstate represents
an atomic wave packet and can be calculated in a series expansion with a master
formula that we derive. The zeroth order of this series expansion describes the
adiabatic limit, whereas the higher order contributions contain the mixing of
the eigenstates and the corresponding amplitude functions.
  We give a tutorial for the theoretical description of longitudinal atomic
beam spin echo experiments and for the so-called Fahrplan model, which is a
visualisation tool for the propagation of wave packets of different atomic
eigenstates.
  As an example for the application of our theory, we study parity violating
geometric (Berry-)phases. In this context, we define geometric flux densities,
which for certain field configurations can be used to illustrate geometric
phases in a vector diagram. Considering an example with a specific field
configuration, we prove the existence of a parity violating geometric phase.


title:
Frequency Windows of Absolute Negative Conductance in Josephson
  Junctions

abstract:
  We report on anomalous conductance in a resistively and capacitively shunted
Josephson junction which is simultaneously driven by ac and dc currents. The
dependence of the voltage across the junction on the frequency of the ac
current shows windows of absolute negative conductance regimes, i.e. for a
positive (negative) dc current, the voltage is negative (positive).


title: Holographic approach to a minimal Higgsless model

abstract:
  In this work, following an holographic approach, we carry out a low energy
effective study of a minimal Higgsless model based on SU(2) bulk symmetry
broken by boundary conditions, both in flat and warped metric. The holographic
procedure turns out to be an useful computation technique to achieve an
effective four dimensional formulation of the model taking into account the
corrections coming from the extra dimensional sector. This technique is used to
compute both oblique and direct contributions to the electroweak parameters in
presence of fermions delocalized along the fifth dimension.


title:
Enhanced strange baryon production in Au+Au collisions compared to p+p
  at sqrts = 200 GeV

abstract:
  We report on the observed differences in production rates of strange and
multi-strange baryons in Au+Au collisions at sqrts = 200 GeV compared to pp
interactions at the same energy. The strange baryon yields in Au+Au collisions,
then scaled down by the number of participating nucleons, are enhanced relative
to those measured in pp reactions. The enhancement observed increases with the
strangeness content of the baryon, and increases for all strange baryons with
collision centrality. The enhancement is qualitatively similar to that observed
at lower collision energy sqrts =17.3 GeV. The previous observations are for
the bulk production, while at intermediate pT, 1 < pT< 4 GeV/c, the strange
baryons even exceed binary scaling from pp yields.


title:
Cantor Singular Continuous Spectrum for Operators Along Interval
  Exchange Transformations

abstract:
  It is shown that Schroedinger operators, with potentials along the shift
embedding of Lebesgue almost every interval exchange transformations, have
Cantor spectrum of measure zero and pure singular continuous for Lebesgue
almost all points of the interval.


title:
Unjamming of Granular Packings due to Local Perturbations: Stability and
  Decay of Displacements

abstract:
  We study the mechanical response generated by local deformations in jammed
packings of rigid disks. Based on discrete element simulations we determine the
critical force of the local perturbation that is needed to break the mechanical
equilibrium and examine the generated displacement field. Displacements decay
as a power law of the distance from the perturbation point. The decay exponent
and the critical force exhibit nontrivial dependence on the friction: Both
quantities are nonmonotonic and have a sharp maximum at the friction
coefficient 0.1. We find that the mechanical response properties are closely
related to the problem of force-indeterminacy where similar nonmonotonic
behavior was observed previously. We establish direct connection between the
critical force and the ensemble of static force networks.


title: The light curve of the companion to PSR B1957+20

abstract:
  We present a new analysis of the light curve for the secondary star in the
eclipsing binary millisecond pulsar system PSR B1957+20. Combining previous
data and new data points at minimum from the Hubble Space Telescope, we have
100% coverage in the R-band. We also have a number of new K_s-band data points,
which we use to constrain the infrared magnitude of the system. We model this
with the Eclipsing Light Curve code (ELC). From the modelling with the ELC code
we obtain colour information about the secondary at minimum light in BVRI and
K. For our best fit model we are able to constrain the system inclination to 65
+/- 2 degrees for pulsar masses ranging from 1.3 -- 1.9 M_sun. The pulsar mass
is unconstrained. We also find that the secondary star is not filling its Roche
lobe. The temperature of the un-irradiated side of the companion is in
agreement with previous estimates and we find that the observed temperature
gradient across the secondary star is physically sustainable.


title: Finite Element Model Updating Using Bayesian Approach

abstract:
  This paper compares the Maximum-likelihood method and Bayesian method for
finite element model updating. The Maximum-likelihood method was implemented
using genetic algorithm while the Bayesian method was implemented using the
Markov Chain Monte Carlo. These methods were tested on a simple beam and an
unsymmetrical H-shaped structure. The results show that the Bayesian method
gave updated finite element models that predicted more accurate modal
properties than the updated finite element models obtained through the use of
the Maximum-likelihood method. Furthermore, both these methods were found to
require the same levels of computational loads.


title:
Condition Monitoring of HV Bushings in the Presence of Missing Data
  Using Evolutionary Computing

abstract:
  The work proposes the application of neural networks with particle swarm
optimisation (PSO) and genetic algorithms (GA) to compensate for missing data
in classifying high voltage bushings. The classification is done using DGA data
from 60966 bushings based on IEEEc57.104, IEC599 and IEEE production rates
methods for oil impregnated paper (OIP) bushings. PSO and GA were compared in
terms of accuracy and computational efficiency. Both GA and PSO simulations
were able to estimate missing data values to an average 95% accuracy when only
one variable was missing. However PSO rapidly deteriorated to 66% accuracy with
two variables missing simultaneously, compared to 84% for GA. The data
estimated using GA was found to classify the conditions of bushings than the
PSO.


title:
Midlatitude Cirrus Clouds and Multiple Tropopauses from a 2002-2006
  Climatology over the SIRTA Observatory

abstract:
  This study present a comparison of lidar observations of midlatitude cirrus
clouds over the SIRTA observatory between 2002 and 2006 with multiple
tropopauses (MT) retrieved from radiosounding temperature profiles. The
temporal variability of MT properties (frequency, thickness) are discussed.
Results show a marked annual cycle, with MT frequency reaching its lowest point
in May (~18% occurrence of MT) and slowly rising to more than 40% in DJF. The
average thickness of the MT also follows an annual cycle, going from less than
1 km in spring to 1.5 km in late autumn. Comparison with lidar observations
show that cirrus clouds show a preference for being located close below the 1st
tropopause. When the cloud top is above the 1st tropopause (7% of
observations), in 20% of cases the cloud base is above it as well, resulting in
a cirrus cloud "sandwiched" between the two tropopauses. Compared to the
general distribution of cirrus, cross-tropopause cirrus show a higher frequency
of large optical depths, while inter-tropopause cirrus show almost exclusively
low optical depths (Tau < 0.03 in 90% of cases) typical of subvisible clouds.
Results suggest the occurrence of inter-tropopause cirrus clouds is correlated
with the frequency of multiple tropopauses.


title: Spectroscopy of Strong-Pulse Superradiance in a Bose-Einstein condensate

abstract:
  We study experimentally superradiance in a Bose-Einstein condensate using a
two-frequency pump beam. By controlling the frequency difference between the
beam components, we measure the spectrum of the backward (energy-mismatched)
superradiant atomic modes. In addition, we show that the populations of these
modes display coherent time-dynamics. These results are compared to a
semi-classical model based on coupled Schroedinger-Maxwell equations.


title:
Faithful Effective-One-Body waveforms of small-mass-ratio coalescing
  black-hole binaries

abstract:
  We address the problem of constructing high-accuracy, faithful analytic
waveforms describing the gravitational wave signal emitted by inspiralling and
coalescing binary black holes. We work within the Effective-One-Body (EOB)
framework and propose a methodology for improving the current
(waveform)implementations of this framework based on understanding, element by
element, the physics behind each feature of the waveform, and on systematically
comparing various EOB-based waveforms with ``exact'' waveforms obtained by
numerical relativity approaches. The present paper focuses on small-mass-ratio
non-spinning binary systems, which can be conveniently studied by
Regge-Wheeler-Zerilli-type methods. Our results include: (i) a resummed,
3PN-accurate description of the inspiral waveform, (ii) a better description of
radiation reaction during the plunge, (iii) a refined analytic expression for
the plunge waveform, (iv) an improved treatment of the matching between the
plunge and ring-down waveforms. This improved implementation of the EOB
approach allows us to construct complete analytic waveforms which exhibit a
remarkable agreement with the ``exact'' ones in modulus, frequency and phase.
In particular, the analytic and numerical waveforms stay in phase, during the
whole process, within $\pm 1.1 %$ of a cycle. We expect that the extension of
our methodology to the comparable-mass case will be able to generate comparably
accurate analytic waveforms of direct use for the ground-based network of
interferometric detectors of gravitational waves.


title: Boosted Black Holes on Kaluza-Klein Bubbles

abstract:
  We construct an exact stationary solution of black hole -- bubble sequence in
the five dimensional Kaluza-Klein theory by using solitonic solution generating
techniques. The solution describes two boosted black holes with topology S^3 on
a Kaluza-Klein bubble and has a linear momentum component in the compactified
direction. The ADM mass and the linear momentum depend on the two boosted
velocity parameters of black holes. In the effective four dimensional theory,
the solution has an electric charge which is proportional to the linear
momentum. The solution includes the static solution found by Elvang and
Horowitz and a limit of single boosted black string.


title: Multipartite entanglement of superpositions

abstract:
  The entanglement of superpositions [Phys. Rev. Lett. 97, 100502 (2006)] is
generalized to the multipartite scenario: an upper bound to the multipartite
entanglement of a superposition is given in terms of the entanglement of the
superposed states and the superposition coefficients. This bound is proven to
be tight for a class of states composed by an arbitrary number of qubits. We
also extend the result to a large family of quantifiers which includes the
negativity, the robustness of entanglement, and the best separable
approximation measure.


title: Forms of higher degree permitting composition

abstract:
  Nondegenerate forms N of degree d on a unital nonassociative algebra A over a
ring R which permit composition, i.e., satisfy N(1)=1 and N(xy)=N(x)N(y) for
all x,y in A, are studied. These forms were first classified by Schafer over
fields of characteristic 0 or >d. We investigate cubic and quartic
nondegenerate forms which permit composition over certain rings and curves.
Classes of highly degenerate cubic forms N over fields which permit composition
are constructed.


title:
Applications of nanoparticles of gamma Fe2O3 for hyperthermia in E.coli
  by Nd:YAG laser

abstract:
  The paper explores the use of nanoparticles of gamma Fe2O3 for hyperthermia
treatment of living organisms by absorption of 1064 nm radiations from Nd:YAG
laser. Escherichia coli cells have been used as the model system for
demonstrating the effect wherein lysine is used as an interface between the
cell walls and the nanoparticles. Scanning Electron Microscopic observations
have, exclusively, proved that attachment of nanoparticles of iron oxide along
with lysine alone is responsible for absorption of above radiations. The
quantitative estimation has been provided by growth rate measurements and
protein assessment of the cells. The nanoparticles of gamma Fe2O3 were
synthesized by DC arc plasma assisted gas phase condensation.


title: Observations of Galactic Gamma-Ray Sources with H.E.S.S

abstract:
  H.E.S.S. results from the first three years of nominal operation are
presented. Among the many exciting measurements that have been made, most
gamma-ray sources are of Galactic origin. I will concentrate here on an
overview of Galactic observations and summarise and discuss observations of
selected objects of the different source types.


title: On the physical meaning of the Unruh effect

abstract:
  We present simple arguments that detectors moving with constant acceleration
(even acceleration for a finite time) should detect particles. The effect is
seen to be universal. Moreover, detectors undergoing linear acceleration and
uniform, circular motion both detect particles for the same physical reason. We
show that if one uses a circularly orbiting electron in a constant external
magnetic field as the Unruh--DeWitt detector, then the Unruh effect physically
coincides with the experimentally verified Sokolov--Ternov effect.


title: Convex-transitive characterizations of Hilbert spaces

abstract:
  In this paper we investigate real convex-transitive Banach spaces X, which
admit a 1-dimensional bicontractive projection P on X. Various mild conditions
regarding the weak topology and the geometry of the norm are provided, which
guarantee that such an X is in fact isometrically a Hilbert space. The results
obtained can be regarded as partial answers to the well-known Banach-Mazur
rotation problem, as well as to a question posed by B. Randrianantoanina in
2002 about convex-transitive spaces.


title: From multiplicative unitaries to quantum groups II

abstract:
  It is shown that all important features of a $\mathrm{C}^*$-algebraic quantum
group $(A,\Delta)$ defined by a modular multiplicative $W$ depend only on the
pair $(A,\Delta)$ rather than the multiplicative unitary operator $W$. The
proof is based on thorough study of representations of quantum groups. As an
application we present a construction and study properties of the universal
dual of a quantum group defined by a modular multiplicative unitary - without
assuming existence of Haar weights.


title:
The Millennium Galaxy Catalogue: The connection between close pairs and
  asymmetry; implications for the galaxy merger rate

abstract:
  We compare the use of galaxy asymmetry and pair proximity for measuring
galaxy merger fractions and rates for a volume limited sample of 3184 galaxies
with -21 < M(B) -5 log h < -18 mag. and 0.010 < z < 0.123 drawn from the
Millennium Galaxy Catalogue. Our findings are that:
  (i) Galaxies in close pairs are generally more asymmetric than isolated
galaxies and the degree of asymmetry increases for closer pairs. At least 35%
of close pairs (with projected separation of less than 20 h^{-1} kpc and
velocity difference of less than 500 km s^{-1}) show significant asymmetry and
are therefore likely to be physically bound.
  (ii) Among asymmetric galaxies, we find that at least 80% are either
interacting systems or merger remnants. However, a significant fraction of
galaxies initially identified as asymmetric are contaminated by nearby stars or
are fragmented by the source extraction algorithm. Merger rates calculated via
asymmetry indices need careful attention in order to remove the above sources
of contamination, but are very reliable once this is carried out.
  (iii) Close pairs and asymmetries represent two complementary methods of
measuring the merger rate. Galaxies in close pairs identify future mergers,
occurring within the dynamical friction timescale, while asymmetries are
sensitive to the immediate pre-merger phase and identify remnants.
  (iv) The merger fraction derived via the close pair fraction and asymmetries
is about 2% for a merger rate of (5.2 +- 1.0) 10^{-4} h^3 Mpc^{-3} Gyr^{-1}.
These results are marginally consistent with theoretical simulations (depending
on the merger time-scale), but imply a flat evolution of the merger rate with
redshift up to z ~1.


title:
Surface waves on metal-dielectric boundaries on the frequency of
  $\omega_{pl}$

abstract:
  Surface optical plasmons on metal-dielectric boundaries of various shapes are
studied. The study features by the exploration of plasmons of the frequency
that is larger than $\omega_{pl}/\sqrt{2}$ and approximately equal to $\omega
_{pl}$. These plasmons exist on thin films, thin cylinders, and on spheres.
Such a plasmon does not exist on a single surface. For applications the use of
plasmons of the ~$\omega_{pl}$ frequency means the promotion of nanophotonics
devices into a short wavelength range. For Ag this means the promotion to the
wavelength of 140 nm.


title: On generation of Crab giant pulses

abstract:
  We propose that Crab giant pulses are generated on closed magnetic field
lines near the light cylinder via anomalous cyclotron resonance on the ordinary
mode. Waves are generated in a set of fine, unequally spaced, narrow emission
bands at frequencies much lower than a local cyclotron frequency. Location of
emission bands is fitted to spectral structures seen by Eilek et al. (2006).
  To reproduce the data, the required density of plasma in the giant pulses
emission region is much higher, by a factor $\sim 3 \times 10^5$, than the
minimal Goldreich-Julian density. Emission is generated by a population of
highly energetic particles with radiation-limited Lorentz factors $\gamma \sim
7 \times 10^7$, produced during occasional reconnection close to the Y point,
where the last closed field lines approach the light cylinder.


title: Classical approach to the graph isomorphism problem using quantum walks

abstract:
  Given the extensive application of classical random walks to classical
algorithms in a variety of fields, their quantum analogue in quantum walks is
expected to provide a fruitful source of quantum algorithms. So far, however,
such algorithms have been scarce. In this work, we enumerate some important
differences between quantum and classical walks, leading to their markedly
different properties. We show that for many practical purposes, the
implementation of quantum walks can be efficiently achieved using a classical
computer. We then develop both classical and quantum graph isomorphism
algorithms based on discrete-time quantum walks. We show that they are
effective in identifying isomorphism classes of large databases of graphs, in
particular groups of strongly regular graphs. We consider this approach to
represent a promising candidate for an efficient solution to the graph
isomorphism problem, and believe that similar methods employing quantum walks,
or derivatives of these walks, may prove beneficial in constructing other
algorithms for a variety of purposes.


title:
Signatures of Heavy Z-prime in the Extra U(1) Superstring Inspired
  Model: RGEs Analysis

abstract:
  In the extra U(1) superstring inspired model, we examine the electroweak and
U(1)-prime symmetry breaking with the singlet and exotic quark D, D+{\c}along
with the study of heavy Z-prime boson in accordance with the top quark mass
region. For this, we have done the analysis of complete renormalization group
equations (RGEs)pertaining to the anomaly free E-{\6}-Eta model of rank 5. The
Z-prime is found to the order of TeV or above with allowed small Z-Zprime
mixing angle, for which the large singlet VEV is required. This is done by
considering the only non-universality of Yukawa couplings at GUT scale because
these do not obey the E-{\6}relationship and also satisfies the unitarity
constraints both at GUT and weak scale, where rest of the parameters, i.e.,
gaugino masses, tri-linear couplings, and soft supersymmetric breaking masses
are kept universal at GUT scale with the gauge couplings unification. The large
value of Yukawa couplings (order of 1) triggered the symmetry breaking
radiatively and induces the effective-Mu parameter at the electroweak scale and
lead to a viable low energy spectrum at weak scale.


title: Dark Energy and Gravity

abstract:
  I review the problem of dark energy focusing on the cosmological constant as
the candidate and discuss its implications for the nature of gravity. Part 1
briefly overviews the currently popular `concordance cosmology' and summarises
the evidence for dark energy. It also provides the observational and
theoretical arguments in favour of the cosmological constant as the candidate
and emphasises why no other approach really solves the conceptual problems
usually attributed to the cosmological constant. Part 2 describes some of the
approaches to understand the nature of the cosmological constant and attempts
to extract the key ingredients which must be present in any viable solution. I
argue that (i)the cosmological constant problem cannot be satisfactorily solved
until gravitational action is made invariant under the shift of the matter
lagrangian by a constant and (ii) this cannot happen if the metric is the
dynamical variable. Hence the cosmological constant problem essentially has to
do with our (mis)understanding of the nature of gravity. Part 3 discusses an
alternative perspective on gravity in which the action is explicitly invariant
under the above transformation. Extremizing this action leads to an equation
determining the background geometry which gives Einstein's theory at the lowest
order with Lanczos-Lovelock type corrections. (Condensed abstract).


title:
Thermal Operator and Dispersion Relation in QED at Finite Temperature
  and Chemical Potential

abstract:
  Combining the thermal operator representation with the dispersion relation in
QED at finite temperature and chemical potential, we determine the complete
retarded photon self-energy only from its absorptive part at zero temperature.
As an application of this method, we show that, even for the case of a nonzero
chemical potential, the temperature dependent part of the one loop retarded
photon self-energy vanishes in $(1+1)$ dimensional massless QED.


title: Informatics Carnot Machine

abstract:
  Based on Planck's blackbody equation it is argued that a single mode light
pulse, with a large number of photons, carries one entropy unit. Similarly, an
empty radiation mode carries no entropy. In this case, the calculated entropy
that a coded sequence of light pulses is carrying is simply the Gibbs mixing
entropy, which is identical to the logical Shannon information. This approach
is supported by a demonstration that information transmission and
amplification, by a sequence of light pulses in an optical fiber, is a classic
Carnot machine comprising of two isothermals and two adiabatic. Therefore it is
concluded that entropy under certain conditions is information.


title:
A Complete Statistical Analysis for the Quadrupole Amplitude in an
  Ellipsoidal Universe

abstract:
  A model of Universe with a small eccentricity due to the presence of a
magnetic field at the decoupling time (i.e. an Ellipsoidal Universe) has been
recently proposed for the solution of the low quadrupole anomaly of the angular
power spectrum of cosmic microwave background anisotropies. We present a
complete statistical analysis of that model showing that the probability of
increasing of the amplitude of the quadrupole is larger than the probability of
decreasing in the whole parameters' space.


title: Reflexivity in Derived Categories

abstract:
  An adjoint pair of contravariant functors between abelian categories can be
extended to the adjoint pair of their derived functors in the associated
derived categories. We describe the reflexive complexes and interpret the
achieved results in terms of objects of the initial abelian categories. In
particular we prove that, for functors of any finite cohomological dimension,
the objects of the initial abelian categories which are reflexive as stalk
complexes form the largest class where a Cotilting Theorem in the sense of
Colby and Fuller works.


title: Multi-Line Geometry of Qubit-Qutrit and Higher-Order Pauli Operators

abstract:
  The commutation relations of the generalized Pauli operators of a
qubit-qutrit system are discussed in the newly established graph-theoretic and
finite-geometrical settings. The dual of the Pauli graph of this system is
found to be isomorphic to the projective line over the product ring Z2xZ3. A
"peculiar" feature in comparison with two-qubits is that two distinct
points/operators can be joined by more than one line. The multi-line property
is shown to be also present in the graphs/geometries characterizing two-qutrit
and three-qubit Pauli operators' space and surmised to be exhibited by any
other higher-level quantum system.


title:
The phase structure of a chirally invariant lattice Higgs-Yukawa model
  for small and for large values of the Yukawa coupling constant

abstract:
  We consider a chirally invariant lattice Higgs-Yukawa model based on the
Neuberger overlap operator. As a first step towards the eventual determination
of Higgs mass bounds we study the phase diagram of the model analytically in
the large Nf-limit. We present an expression for the effective potential at
tree-level in the regime of small Yukawa and quartic coupling constants and
determine the order of the phase transitions. In the case of strong Yukawa
couplings the model effectively becomes an O(4)-symmetric non-linear
sigma-model for all values of the quartic coupling constant. This leads to the
existence of a symmetric phase also in the regime of large values of the Yukawa
coupling constant. On finite and small lattices, however, strong finite volume
effects prevent the expectation value of the Higgs field from vanishing thus
obscuring the existence of the symmetric phase at strong Yukawa couplings.


title:
A Bayesian approach to the estimation of maps between riemannian
  manifolds

abstract:
  Let \Theta be a smooth compact oriented manifold without boundary, embedded
in a euclidean space and let \gamma be a smooth map \Theta into a riemannian
manifold \Lambda. An unknown state \theta \in \Theta is observed via
X=\theta+\epsilon \xi where \epsilon>0 is a small parameter and \xi is a white
Gaussian noise. For a given smooth prior on \Theta and smooth estimator g of
the map \gamma we derive a second-order asymptotic expansion for the related
Bayesian risk. The calculation involves the geometry of the underlying spaces
\Theta and \Lambda, in particular, the integration-by-parts formula. Using this
result, a second-order minimax estimator of \gamma is found based on the modern
theory of harmonic maps and hypo-elliptic differential operators.


title: Tailoring optical nonlinearities via the Purcell effect

abstract:
  We predict that the effective nonlinear optical susceptibility can be
tailored using the Purcell effect. While this is a general physical principle
that applies to a wide variety of nonlinearities, we specifically investigate
the Kerr nonlinearity. We show theoretically that using the Purcell effect for
frequencies close to an atomic resonance can substantially influence the
resultant Kerr nonlinearity for light of all (even highly detuned) frequencies.
For example, in realistic physical systems, enhancement of the Kerr coefficient
by one to two orders of magnitude could be achieved.


title: A soft X-ray study of Type I AGN observed with Chandra HETGS

abstract:
  We present the results of a uniform analysis of the soft X-ray spectra of
fifteen type I AGN observed with the high resolution X-ray gratings on board
\emph{Chandra}. We found that ten of the fifteen AGN exhibit signatures of an
intrinsic ionized absorber. The absorbers are photoionized and outflowing, with
velocities in the range $\sim 10^{1}-10^{3}$ km $\rm{s}^{-1}$. The column
density of the warm absorbing gas is $\sim 10^{20-23} \rm{cm}^{-2}$. Nine of
the ten AGN exhibiting warm absorption are best--fit by multiple ionization
components and three of the ten AGN \emph{require} multiple kinematic
components. The warm absorbing gas in our AGN sample has a wide range of
ionization parameter, spanning roughly four orders of magnitude ($\xi \sim
10^{0-4}$ ergs cm $\rm{s}^{-1}$) in total, and often spanning three orders of
magnitude in the same gas. Warm absorber components with ionization parameter
$\xi<10$ generate an unresolved transition array due to Fe in seven of the ten
AGN exhibiting warm absorption. These low ionization state absorbers may also
carry away the largest mass outflows from the AGN. The mass outflow rate
depends critically on the volume filling factor of the gas, which cannot yet be
directly measured. However, upper limits on the mass outflow ratesfor filling
factors of unity can be much greater than the expected accretion rate onto the
central supermassive black hole and filling factors as small as 1% can give
outflow rates comparable to the accretion rate. There appears to be a gap in
the outflow velocities in our sample between $\sim 300-500$ km $\rm{s}^{-1}$,
the origin of which is not clear. The outflow components with velocities below
this gap tend to be associated with lower column densities than those with
velocities above the gap.


title:
The Lorentz factor distribution and luminosity function of relativistic
  jets in AGNs

abstract:
  The observed apparent velocities and luminosities of the relativistic jets in
AGNs are significantly different from their intrinsic values due to strong
special relativistic effects. We adopt the maximum likelihood method to
determine simultaneously the intrinsic luminosity function and the Lorentz
factor distribution of a sample of AGNs. The values of the best estimated
parameters are consistent with the previous results, but with much better
accuracy. In previous study, it was assumed that the shape of the observed
luminosity function of Fanaroff-Riley type II radio galaxies is the same with
the intrinsic luminosity function of radio loud quasars. Our results prove the
validity of this assumption. We also find that low and high redshift groups
divided by z=0.1 are likely to be from different parent populations.


title:
Criticality in the configuration-mixed interacting boson model : (1)
  $U(5)-\hat{Q}(\chi)\cdot\hat{Q}(\chi)$ mixing

abstract:
  The case of U(5)--$\hat{Q}(\chi)\cdot\hat{Q}(\chi)$ mixing in the
configuration-mixed Interacting Boson Model is studied in its mean-field
approximation. Phase diagrams with analytical and numerical solutions are
constructed and discussed. Indications for first-order and second-order shape
phase transitions can be obtained from binding energies and from critical
exponents, respectively.


title:
Effect of the spin-orbit interaction on the thermodynamic properties of
  crystals: The specific heat of bismuth

abstract:
  In recent years, there has been increasing interest in the specific heat $C$
of insulators and semiconductors because of the availability of samples with
different isotopic masses and the possibility of performing \textit{ab initio}
calculations of its temperature dependence $C(T)$ using as a starting point the
electronic band structure. Most of the crystals investigated are elemental
(e.g., germanium) or binary (e.g., gallium nitride) semiconductors. The initial
electronic calculations were performed in the local density approximation and
did not include spin-orbit interaction. Agreement between experimental and
calculated results was usually found to be good, except for crystals containing
heavy atoms (e.g., PbS) for which discrepancies of the order of 20% existed at
the low temperature maximum found for $C/T^3$. It has been conjectured that
this discrepancies result from the neglect of spin-orbit interaction which is
large for heavy atoms ($\Delta_0\sim$1.3eV for the $p$ valence electrons of
atomic lead). Here we discuss measurements and \textit{ab initio} calculations
of $C(T)$ for crystalline bismuth ($\Delta_0\sim$1.7 eV), strictly speaking a
semimetal but in the temperature region accessible to us ($T >$ 2K) acting as a
semiconductor. We extend experimental data available in the literature and
notice that the \textit{ab initio} calculations without spin-orbit interaction
exhibit a maximum at $\sim$8K, about 20% lower than the measured one. Inclusion
of spin-orbit interaction decreases the discrepancy markedly: The maximum of
$C(T)$ is now only 7% larger than the measured one. Exact agreement is obtained
if the spin-orbit hamiltonian is reduced by a factor of $\sim$0.8.


title:
On asymptotic dimension of amalgamated products and right-angled Coxeter
  groups

abstract:
  We prove the inequality $$ \as A\ast_CB\le\max\{\as A,\as B,\as C+1\} $$ and
we apply this inequality to show that the asymptotic dimension of any
right-angled Coxeter group does not exceed the dimension of its Davis' complex.


title: Some remarks on spherical harmonics

abstract:
  The article contains several observations on spherical harmonics and their
nodal sets: a construction for harmonics with prescribed zeroes; a kind of
canonical representation of this type for harmonics on $\bbS^2$; upper and
lower bounds for nodal length and inner radius (the upper bounds are sharp);
precise upper bound for the number of common zeroes of two spherical harmonics
on $\bbS^2$; the mean Hausdorff measure on the intersection of $k$ nodal sets
for harmonics of different degrees on $\bbS^m$, where $k\leq m$ (in particular,
the mean number of common zeroes of $m$ harmonics).


title:
The polarization in the JVAS/CLASS flat-spectrum radio sources: II. A
  search for aligned radio polarizations

abstract:
  We have used the very large JVAS/CLASS 8.4-GHz surveys of flat-spectrum radio
sources to test the hypothesis that there is a systematic alignment of
polarization position angle vectors on cosmological scales of the type claimed
by Hutsemekers et al (2005). The polarization position angles of 4290 sources
with polarized flux density >=1 mJy have been examined. They do not reveal
large-scale alignments either as a whole or when split in half into
high-redshift (z >= 1.24) and low-redshift sub-samples. Nor do the radio
sources which lie in the specific areas covered by Hutsemekers et al (2005).
show any significant effect. We have also looked at the position angles of
parsec-scale jets derived from VLBI observations and again find no evidence for
systematic alignments. Finally, we have investigated the correlation between
the polarization position angle and those of the parsec-scale jets. As
expected, we find that there is a tendency for the polarization angles to be
perpendicular to the jet angles. However, the difference in jet and
polarization position angles does not show any systematic trend in different
parts of the sky.


title: Optimal discrimination between quantum operations

abstract:
  In this paper, we address the problem of discriminating two given quantum
operations. Firstly, based on the Bloch representation of single qubit systems,
we give the exact minimum error probability of discriminating two single qubit
quantum operations by unentangled input states. In particular, for the Pauli
channels discussed in [Phys. Rev. A {\bf 71}, 062340 (2005)], we use a more
intuitional and visual method to deal with their discrimination problem.
Secondly, we consider the condition for perfect discrimination of two quantum
operations. Specially, we get that two generalized Pauli channels are perfectly
distinguishable if and only if their characteristic vectors are orthogonal.


title: Electronic structure and optical properties of ZnX (X=O, S, Se, Te)

abstract:
  Electronic band structure and optical properties of zinc monochalcogenides
with zinc-blende- and wurtzite-type structures were studied using the ab initio
density functional method within the LDA, GGA, and LDA+U approaches.
Calculations of the optical spectra have been performed for the energy range
0-20 eV, with and without including spin-orbit coupling. Reflectivity,
absorption and extinction coefficients, and refractive index have been computed
from the imaginary part of the dielectric function using the Kramers--Kronig
transformations. A rigid shift of the calculated optical spectra is found to
provide a good first approximation to reproduce experimental observations for
almost all the zinc monochalcogenide phases considered. By inspection of the
calculated and experimentally determined band-gap values for the zinc
monochalcogenide series, the band gap of ZnO with zinc-blende structure has
been estimated.


title: Network Topology of an Experimental Futures Exchange

abstract:
  Many systems of different nature exhibit scale free behaviors. Economic
systems with power law distribution in the wealth is one of the examples. To
better understand the working behind the complexity, we undertook an empirical
study measuring the interactions between market participants. A Web server was
setup to administer the exchange of futures contracts whose liquidation prices
were coupled to event outcomes. After free registration, participants started
trading to compete for the money prizes upon maturity of the futures contracts
at the end of the experiment. The evolving `cash' flow network was
reconstructed from the transactions between players. We show that the network
topology is hierarchical, disassortative and scale-free with a power law
exponent of 1.02+-0.09 in the degree distribution. The small-world property
emerged early in the experiment while the number of participants was still
small. We also show power law distributions of the net incomes and
inter-transaction time intervals. Big winners and losers are associated with
high degree, high betweenness centrality, low clustering coefficient and low
degree-correlation. We identify communities in the network as groups of the
like-minded. The distribution of the community sizes is shown to be power-law
distributed with an exponent of 1.19+-0.16.


title:
On the equilibrium morphology of systems drawn from spherical collapse
  experiments

abstract:
  We present a purely theoretical study of the morphological evolution of
self-gravitating systems formed through the dissipationless collapse of N-point
sources. We explore the effects of resolution in mass and length on the growth
of triaxial structures formed by an instability triggered by an excess of
radial orbits. We point out that as resolution increases, the equilibria shift,
from mildly prolate, to oblate. A number of particles N ~= 100000 or larger is
required for convergence of axial aspect ratios. An upper bound for the
softening, e ~ 1/256, is also identified. We then study the properties of a set
of equilibria formed from scale-free cold initial mass distributions, ro ~ r^-g
with 0 <= g <= 2. Oblateness is enhanced for initially more peaked structures
(larger values of g). We map the run of density in space and find no evidence
for a power-law inner structure when g <= 3/2 down to a mass fraction <~0.1 per
cent of the total. However, when 3/2 < g <= 2, the mass profile in equilibrium
is well matched by a power law of index ~g out to a mass fraction ~ 10 per
cent. We interpret this in terms of less-effective violent relaxation for more
peaked profiles when more phase mixing takes place at the centre. We map out
the velocity field of the equilibria and note that at small radii the velocity
coarse-grained distribution function (DF) is Maxwellian to a very good
approximation.


title:
Decorrelation of samples in Quantum Monte Carlo calculations and scaling
  of autocorrelation time in Li and H$_{2}$O clusters

abstract:
  We have investigated decorrelation of samples in Quantum Monte Carlo (QMC)
ground-state energy calculations for large Li and H$_{2}$O nanoclusters.
Binning data as a way of eliminating statistical correlations, as is the common
practice, is found to become increasingly impractical as the system size grows.
We demonstrate nevertheless that it is possible to perform accurate energy
calculations - without decorrelating samples - by exploiting the scaling of the
integrated autocorrelation time $\tau$ as a function of the number of electrons
in the system.


title: The Axiomatisation of Physics

abstract:
  Analysing Quantum Measurement requires analysing the physics of amplification
since amplification of phenomena from one scale to another scale is essential
to measurement. There still remains the task of working this into an axiomatic
logical structure, what should be the foundational status of the concepts of
measurement and probability. We argue that the concept of physical probability
is a multi-scale phenomenon and as such, can be explicitly defined in terms of
more fundamental physical concepts. Thus Quantum Mechanics can be given a
logically unexceptionable axiomatisation. We introduce a new definition of
macroscopic observable which implements Bohr's insight that the observables of
a measurement apparatus are classical in nature. In particular, we obtain the
usual non-abelian observables as limits of abelian, classical, observables.
This is the essential step in Hilbert's Sixth Problem.


title: A Generalisation of Dyson's Integration Theorem for Determinants

abstract:
  Dyson's integration theorem is widely used in the computation of eigenvalue
correlation functions in Random Matrix Theory. Here we focus on the variant of
the theorem for determinants, relevant for the unitary ensembles with Dyson
index beta = 2. We derive a formula reducing the (n-k)-fold integral of an n x
n determinant of a kernel of two sets of arbitrary functions to a determinant
of size k x k. Our generalisation allows for sets of functions that are not
orthogonal or bi-orthogonal with respect to the integration measure. In the
special case of orthogonal functions Dyson's theorem is recovered.

categories: math-ph cond-mat.stat-mech hep-th math.MP


title: Satellite survival in cold dark matter cosmology

abstract:
  We study the survival of substructures (clumps) within larger
self-gravitating dark matter halos. Building on scaling relations obtained from
N-body calculations of violent relaxation, we argue that the tidal field of
galaxies and halos can only destroy substructures if spherical symmetry is
imposed at formation. We explore other mechanisms that may tailor the number of
halo substructures during the course of virialization. Unless the larger halo
is built up from a few large clumps, we find that clump-clump encounters are
unlikely to homogenize the halo on a dynamical timescale. Phase mixing would
proceed faster in the inner parts and allow for the secular evolution of a
stellar disk.