title: The Spectral Shape of the Gamma-ray Background from Blazars

abstract:
  The spectral shape of the unresolved emission from different classes of
gamma-ray emitters can be used to disentangle the contributions from these
populations to the extragalactic gamma-ray background (EGRB). We present a
calculation of the unabsorbed spectral shape of the unresolved blazar
contribution to the EGRB starting from the spectral index distribution (SID) of
resolved EGRET blazars derived through a maximum-likelihood analysis accounting
for measurement errors. In addition, we explicitly calculate the uncertainty in
this theoretically predicted spectral shape, which enters through the spectral
index distribution parameters. We find that: (a) the unresolved blazar emission
spectrum is only mildly convex, and thus, even if blazars are shown by GLAST to
be a dominant contribution to the ERGB at lower energies, they may be
insufficient to explain the EGRB at higher energies; (b) the theoretically
predicted unresolved spectral shape involves significant uncertainties due to
the limited constraints provided by EGRET data on the SID parameters, which are
comparable to the statistical uncertainties of the observed EGRET EGRB at high
energies; (c) the increased number statistics which will be provided by GLAST
will be sufficient to reduce this uncertainty by at least a factor of three.


title:
Elemental Abundances of Blue Compact Dwarfs from mid-IR Spectroscopy
  with Spitzer

abstract:
  We present a study of elemental abundances in a sample of thirteen Blue
Compact Dwarf (BCD) galaxies, using the $\sim$10--37$\mu$m high resolution
spectra obtained with Spitzer/IRS. We derive the abundances of neon and sulfur
for our sample using the infrared fine-structure lines probing regions which
may be obscured by dust in the optical and compare our results with similar
infrared studies of starburst galaxies from ISO. We find a good correlation
between the neon and sulfur abundances, though sulfur is under-abundant
relative to neon with respect to the solar value. A comparison of the elemental
abundances (neon, sulfur) measured from the infrared data with those derived
from the optical (neon, sulfur, oxygen) studies reveals a good overall
agreement for sulfur, while the infrared derived neon abundances are slightly
higher than the optical values. This indicates that either the metallicities of
dust enshrouded regions in BCDs are similar to the optically accessible
regions, or that if they are different they do not contribute substantially to
the total infrared emission of the host galaxy.


title:
Synchronization problems for unidirectional feedback coupled nonlinear
  systems

abstract:
  In this paper we consider three different synchronization problems consisting
in designing a nonlinear feedback unidirectional coupling term for two
(possibly chaotic) dynamical systems in order to drive the trajectories of one
of them, the slave system, to a reference trajectory or to a prescribed
neighborhood of the reference trajectory of the second dynamical system: the
master system. If the slave system is chaotic then synchronization can be
viewed as the control of chaos; namely the coupling term allows to suppress the
chaotic motion by driving the chaotic system to a prescribed reference
trajectory. Assuming that the entire vector field representing the velocity of
the state can be modified, three different methods to define the nonlinear
feedback synchronizing controller are proposed: one for each of the treated
problems. These methods are based on results from the small parameter
perturbation theory of autonomous systems having a limit cycle, from nonsmooth
analysis and from the singular perturbation theory respectively. Simulations to
illustrate the effectiveness of the obtained results are also presented.


title: A refined analysis of the remarkable Bp star HR 6000

abstract:
  UVES spectra of the very young (~10^7 years) peculiar B-type star HR 6000
were analyzed in the near-UV and visual spectral regions (3050-9460 A) with the
aim to extend to other spectral ranges the study made previously in the UV
using IUE spectra. Stellar parameters Teff=12850K, logg=4.10, and xi=0km/s, as
determined from H_beta, H_gamma, H_delta Balmer profiles and from the Fe I, Fe
II ionization equilibrium, were used to compute an individual abundances
ATLAS12 model. We identified spectral peculiarities and obtained final stellar
abundances by comparing observed and computed equivalent widths and line
profiles. The adopted model fails to reproduce the (b-y) and c color indices.
The spectral analysis has revealed: the presence of emission lines for Mn II,
Cr II, and Fe II; isotopic anomalies for Hg, Ca; the presence of interstellar
lines of Na I at lambda lambda 3302.3, 3302.9, 5890, 5896 A, and of K I at
7665, 7699 A; the presence of a huge quantity of unidentified lines, which we
presume to be mostly due to Fe II transitions owing to the large Fe
overabundance amounting to [+0.7]. The main chemical peculiarities are an
extreme overabundance of Xe, followed by those of Hg, P, Y, Mn, Fe, Be, and Ti.
The most underabundant element is Si, followed by C, N, Al, S, Mg, V, Sr, Co,
Cl, Sc, and Ni. The silicon underabundance [-2.9] is the lowest value for Si
ever observed in any HgMn star. The observed lines of He I can not be
reproduced by a single value of the He abundance, but they require values
ranging from [-0.8] to [-1.6]. Furthermore, when the observed and computed
wings of He I lines are fitted, the observed line cores are much weaker than
the computed ones. From the present analysis we infer the presence of vertical
abundance stratification for He, Mn, and possibly also P.


title: Poincare index and periodic solutions of perturbed autonomous systems

abstract:
  The basic tool of classical results by Malkin and Melnikov on bifurcation of
periodic solutions from nondegenerate cycles of autonomous systems with
periodic perturbations is an implicit function theorem. In this paper the
Poincare index is used to avoid the requirement of nondegeneracity for the
unperturbed cycles and to provide additional geometrical properties of periodic
solutions of the perturbed system.


title:
Surface Brightness Profiles of Composite Images of Compact Galaxies at
  z~4-6 in the HUDF

abstract:
  The Hubble Ultra Deep Field (HUDF) contains a significant number of B, V and
i'-band dropout objects, many of which were recently confirmed to be young
star-forming galaxies at z~4-6. These galaxies are too faint individually to
accurately measure their radial surface brightness profiles. Their average
light profiles are potentially of great interest, since they may contain clues
to the time since the onset of significant galaxy assembly. We separately
co-add V, i' and z'-band HUDF images of sets of z~4,5 and 6 objects,
pre-selected to have nearly identical compact sizes and the roundest shapes.
  From these stacked images, we are able to study the averaged radial structure
of these objects at much higher signal-to-noise ratio than possible for an
individual faint object. Here we explore the reliability and usefulness of a
stacking technique of compact objects at z~4-6 in the HUDF. Our results are:
(1) image stacking provides reliable and reproducible average surface
brightness profiles; (2) the shape of the average surface brightness profiles
show that even the faintest z~4-6 objects are resolved; and (3) if late-type
galaxies dominate the population of galaxies at z~4-6, as previous HST studies
have shown, then limits to dynamical age estimates for these galaxies from
their profile shapes are comparable with the SED ages obtained from the
broadband colors. We also present accurate measurements of the sky-background
in the HUDF and its associated 1-sigma uncertainties.


title:
Dissociative electron attachment to the H2O molecule. I. Complex-valued
  potential-energy surfaces for the 2B1, 2A1, and 2B2 metastable states of the
  water anion

abstract:
  We present the results of calculations defining global, three-dimensional
representations of the complex-valued potential-energy surfaces of the doublet
B1, doublet A1, and doublet B2 metastable states of the water anion that
underlie the physical process of dissociative electron attachment to water. The
real part of the resonance energies is obtained from configuration-interaction
calculations performed in a restricted Hilbert space, while the imaginary part
of the energies (the widths) is derived from complex Kohn scattering
calculations. A diabatization is performed on the 2A1 and 2B2 surfaces, due to
the presence of a conical intersection between them. We discuss the
implications that the shapes of the constructed potential-energy surfaces will
have upon the nuclear dynamics of dissociative electron attachment to H2O.
  This work originally appeared as Phys Rev A 75, 012710 (2007). Typesetting
errors in the published version have been corrected here.


title:
Bio-linguistic transition and Baldwin effect in an evolutionary
  naming-game model

abstract:
  We examine an evolutionary naming-game model where communicating agents are
equipped with an evolutionarily selected learning ability. Such a coupling of
biological and linguistic ingredients results in an abrupt transition: upon a
small change of a model control parameter a poorly communicating group of
linguistically unskilled agents transforms into almost perfectly communicating
group with large learning abilities. When learning ability is kept fixed, the
transition appears to be continuous. Genetic imprinting of the learning
abilities proceeds via Baldwin effect: initially unskilled communicating agents
learn a language and that creates a niche in which there is an evolutionary
pressure for the increase of learning ability.Our model suggests that when
linguistic (or cultural) processes became intensive enough, a transition took
place where both linguistic performance and biological endowment of our species
experienced an abrupt change that perhaps triggered the rapid expansion of
human civilization.

categories: cs.CL cond-mat.stat-mech cs.AI physics.soc-ph q-bio.PE


title:
On algebraic time-derivative estimation and deadbeat state
  reconstruction

abstract:
  This note places into perspective the so-called algebraic time-derivative
estimation method recently introduced by Fliess and co-authors with standard
results from linear state-space theory for control systems. In particular, it
is shown that the algebraic method can in a sense be seen as a special case of
deadbeat state estimation based on the reconstructibility Gramian of the
considered system.


title: Negative Refraction Requires Strong Inhomogeneity

abstract:
  The paper establishes explicit lower bounds for the lattice cell size of
periodic structures (metamaterials and photonic crystals) capable of supporting
backward waves and producing negative refraction. At optical frequencies, this
result implies strong inhomogeneity, in the sense that the cell size cannot be
negligible relative to the vacuum wavelength and the Bloch wavelength.


title:
The Segal-Bargmann transform for compact quotients of symmetric spaces
  of the complex type

abstract:
  Let G/K be a Riemannian symmetric space of the complex type, meaning that G
is complex semisimple and K is a compact real form. Now let {\Gamma} be a
discrete subgroup of G that acts freely and cocompactly on G/K. We consider the
Segal--Bargmann transform, defined in terms of the heat equation, on the
compact quotient {\Gamma}\G/K. We obtain isometry and inversion formulas
precisely parallel to the results we obtained previously for globally symmetric
spaces of the complex type. Our results are as parallel as possible to the
results one has in the dual compact case. Since there is no known Gutzmer
formula in this setting, our proofs make use of double coset integrals and a
holomorphic change of variable.


title: Lagrangian Relaxation for MAP Estimation in Graphical Models

abstract:
  We develop a general framework for MAP estimation in discrete and Gaussian
graphical models using Lagrangian relaxation techniques. The key idea is to
reformulate an intractable estimation problem as one defined on a more
tractable graph, but subject to additional constraints. Relaxing these
constraints gives a tractable dual problem, one defined by a thin graph, which
is then optimized by an iterative procedure. When this iterative optimization
leads to a consistent estimate, one which also satisfies the constraints, then
it corresponds to an optimal MAP estimate of the original model. Otherwise
there is a ``duality gap'', and we obtain a bound on the optimal solution.
Thus, our approach combines convex optimization with dynamic programming
techniques applicable for thin graphs. The popular tree-reweighted max-product
(TRMP) method may be seen as solving a particular class of such relaxations,
where the intractable graph is relaxed to a set of spanning trees. We also
consider relaxations to a set of small induced subgraphs, thin subgraphs (e.g.
loops), and a connected tree obtained by ``unwinding'' cycles. In addition, we
propose a new class of multiscale relaxations that introduce ``summary''
variables. The potential benefits of such generalizations include: reducing or
eliminating the ``duality gap'' in hard problems, reducing the number or
Lagrange multipliers in the dual problem, and accelerating convergence of the
iterative optimization procedure.


title: Using evolutionary algorithms to extract field theory mass spectra

abstract:
  The spectrum of masses from a lattice QCD simulation may be found by fitting
exponential functions to correlators of operators possessing the quantum
numbers of the particles of interest. The ability of evolutionary algorithms to
find globally optimized solutions containing a variable number of states across
multiple data sets is exploited to provide a promising solution to the problem
of finding these fits.


title:
Using Chemistry to Unveil the Kinematics of Starless Cores: Complex
  Radial Motions in Barnard 68

abstract:
  We present observations of 13CO, C18O, HCO+, H13CO+, DCO+ and N2H+ line
emission towards the Barnard 68 starless core. The line profiles are
interpreted using a chemical network coupled with a radiative transfer code in
order to reconstruct the radial velocity profile of the core. Our observations
and modeling indicate the presence of complex radial motions, with the inward
motions in the outer layers of the core but outward motions in the inner part,
suggesting radial oscillations. The presence of such oscillation would imply
that B68 is relatively old, typically one order of magnitude older than the age
inferred from its chemical evolution and statistical core lifetimes. Our study
demonstrates that chemistry can be used as a tool to constrain the radial
velocity profiles of starless cores.


title: Fluid turbulence and eddy viscosity in relativistic heavy-ion collisions

abstract:
  The eddy viscosity for a turbulent compressible fluid with a relativistic
equation of state is derived. Compressibility allows for sound modes, but the
eddy viscosity in the shear mode is found to be the same as for incompressible
fluids. For two space dimensions (which is the relevant case for the dynamics
of relativistic heavy-ion collisions) the eddy viscosity in the shear mode is
negative, reducing the effective viscosity below its microscopic value. This
could explain the tiny viscosity found at RHIC. Implications for the
experimentally accessible elliptic flow coefficient at the LHC are speculated
on.


title: Improvement of the pion spectrum with HYP-smeared staggered fermions

abstract:
  We extend our previous study of taste-symmetry breaking using HYP-smeared
staggered fermions in two ways. First, we improve the statistics of a
comparison of unimproved and HYP-smeared staggered fermions on quenched
lattices with $a\approx 0.1 $fm. This allows us to obtain a signal for all pion
tastes, rather than just a subset, and thus to make a complete comparison. In
addition, it allows us to differentiate between wall and local sources. Second,
we compare HYP-smeared valence quarks to asqtad valence quarks on 2+1 flavor
unquenched MILC lattices. We find that taste breaking is substantially reduced
by HYP-smearing, bringing the size of this discretization effect (which is the
dominant such effect with staggered fermions) down to the size expected
generically for any fermion type.


title:
Comment on "Critique of the foundations of time-dependent density
  functional theory" [Phys. Rev.A. 75, 022513 (2007)]

abstract:
  A recent paper (Phys. Rev A. 75, 022513 (2007), arXiv:cond-mat/0602020)
challenges exact time-dependent density functional theory (TDDFT) on several
grounds. We explain why these criticisms are either irrelevant or incorrect,
and that TDDFT is both formally exact and predictive.


title: The Glue Content of the Pion

abstract:
  We perform a quenched computation of the glue momentum fraction in the pion.
Different discretizations of the gluonic energy-momentum tensor are studied on
the lattice for that purpose. We discuss some implications based on the
momentum sum rule. Finally we point out promising applications of the
techniques developed here.


title: A Probability Model for Lifetime of Wireless Sensor Networks

abstract:
  Considering a wireless sensor network whose nodes are distributed randomly
over a given area, a probability model for the network lifetime is provided.
Using this model and assuming that packet generation follows a Poisson
distribution, an analytical expression for the complementary cumulative density
function (ccdf) of the lifetime is obtained. Using this ccdf, one can
accurately find the probability that the network achieves a given lifetime. It
is also shown that when the number of sensors, $N$, is large, with an error
exponentially decaying with $N$, one can predict whether or not a certain
lifetime can be achieved. The results of this work are obtained for both
multi-hop and single-hop wireless sensor networks and are verified with
computer simulation. The approaches of this paper are shown to be applicable to
other packet generation models and the effect of the area shape is also
investigated.


title: New families of cryptographic systems

abstract:
  A symmetric encryption method based on properties of quasicrystals is
proposed. The advantages of the cipher are strict aperiodicity and everywhere
discontinuous property as well as the speed of computation, simplicity of
implementation and a straightforward possibility of extending the method to
encryption of higher dimensional data.


title: Astronomical constraints on some long-range models of modified gravity

abstract:
  In this paper we use the corrections to the usual Newton-Einstein secular
precessions of the perihelia of the inner planets of the Solar System,
phenomenologically estimated as solve-for parameters by the Russian astronomer
E.V. Pitjeva by fitting almost one century of data with the EPM2004
ephemerides, in order to constrain some long-range models of modified gravity
recently put forth to address the dark energy and dark matter problems. The
models examined here are the four-dimensional ones obtained with the addition
of inverse powers and logarithm of some curvature invariants, and the
multidimensional braneworld model by Dvali, Gabadadze and Porrati (DGP). After
working out the analytical expressions of the secular perihelion precessions
induced by the corrections to the Newtonian potential of such models, we
compare them to the estimated corrections to the rates of perihelia by taking
their ratio for different pairs of planets instead of using one perihelion at a
time for each planet separately, as done so far in literature. As a result, the
curvature invariants-based models are ruled out, even by re-scaling by a factor
10 the errors in the planetary orbital parameters estimated by Pitjeva. Less
neat is the situation for the DGP model. Only the general relativistic
Lense-Thirring effect, not included, as the other exotic models considered
here, by Pitjeva in the dynamical force models used in the estimation process,
passes such a test. It would be important to repeat the present analysis by
using corrections to the precessions of perihelia independently estimated by
other teams of astronomers as well, but, at present, such rates are not yet
available.


title:
Pairing with Unconventional Symmetry around BCS-BEC Crossover: Fermionic
  Atoms in 2D Optical Lattices to Correlated Electron Systems

abstract:
  We study superfluid properties of fermions on a 2D lattice using a
finite-range pairing interaction derivable from an extended Hubbard model. We
obtain signatures of unconventional pair-symmetry states, $d_{x^2-y^2}$ and
extended-s ($s^*$), in the BCS-BEC crossover region. The fermion momentum
distribution function, $v_k^2$, the ratio of the Bogoliubov coefficients,
$v_k/u_k$, and the Fourier transform of $v_k^2$ are among the properties that
are strikingly different for d- and $s^*$ symmetries in the crossover region.
Fermionic atoms in 2D optical lattices may provide a way to observe these
signatures. We discuss possible experimental ramifications of our results.


title:
Optimized Broad-Histogram Ensembles for the Simulation of Quantum
  Systems

abstract:
  The efficiency of statistical sampling in broad-histogram Monte Carlo
simulations can be considerably improved by optimizing the simulated extended
ensemble for fastest equilibration. Here we describe how a recently developed
feedback algorithm can be generalized to find optimized sampling distributions
for the simulation of quantum systems in the context of the stochastic series
expansion (SSE) when defining an extended ensemble in the expansion order. If
the chosen update method is efficient, such as non-local updates for systems
undergoing a second-order phase transition, the optimized ensemble is
characterized by a flat histogram in the expansion order if a variable-length
formulation of the SSE is used. Whenever the update method suffers from
slowdown, such as at a first-order phase transition, the feedback algorithm
shifts weight towards the expansion orders in the transition region, resulting
in a non-uniform histogram.


title: Search for Ultra-High Energy Photons with the Pierre Auger Observatory

abstract:
  Data taken at the Pierre Auger Observatory are used to search for air showers
initiated by ultra-high energy (UHE) photons. Results of searches are reported
from hybrid observations where events are measured with both fluorescence and
array detectors. Additionally, a more stringent test of the photon fluxes
predicted with energies above 10^19 eV is made using a larger data set measured
using only the surface detectors of the observatory.


title: Irrational Stable Commutator Length in Finitely Presented Groups

abstract:
  We give examples of finitely presented groups containing elements with
irrational (in fact, transcendental) stable commutator length, thus answering
in the negative a question of M. Gromov. Our examples come from 1-dimensional
dynamics, and are related to the generalized Thompson groups studied by M.
Stein, I. Liousse and others.


title: Ramsey numbers of sparse hypergraphs

abstract:
  We give a short proof that any k-uniform hypergraph H on n vertices with
bounded degree \Delta has Ramsey number at most c(\Delta, k)n, for an
appropriate constant c(\Delta, k). This result was recently proved by several
authors, but those proofs are all based on applications of the hypergraph
regularity method. Here we give a much simpler, self-contained proof which uses
new techniques developed recently by the authors together with an argument of
Kostochka and R\"odl. Moreover, our method demonstrates that, for k \geq 4,
c(\Delta, k) \leq 2^{2^{\Ddots^{2^{c \Delta}}}}, where the tower is of height k
and the constant c depends on k. It significantly improves on the
Ackermann-type upper bound that arises from the regularity proofs, and we
present a construction which shows that, at least in certain cases, this bound
is not far from best possible. Our methods also allows us to prove quite sharp
results on the Ramsey number of hypergraphs with at most m edges.


title: Constraints on Unparticles from Low Energy Neutrino-Electron Scattering

abstract:
  We place limits on scalar and vector unparticle couplings to electrons and
neutrinos using data from reactor neutrino experiments originally designed to
search for neutrino magnetic moment. Upper bounds on Standard Model
lepton-scalar unparticle and lepton-vector unparticle couplings $\lambda_0$,
and $\lambda_1$ are given for various values of the unparticle mass dimension
d, and the unparticle energy scale $\Lambda_{\cal U}$. Especially for smaller
values of the mass dimension d (1 <d <1.3) these bounds are very significant
and comparable to those obtained from production rates at high energy
colliders. These bounds are also similar to those obtained by the analysis of
the absence of the decay of the low-energy solar and reactor neutrinos.


title: Candidate Rotating Toroids around High-Mass (Proto)Stars

abstract:
  Using the OVRO, Nobeyama, and IRAM mm-arrays, we searched for
``disk''-outflow systems in three high-mass (proto)star forming regions:
G16.59-0.05, G23.01-0.41, and G28.87+0.07. These were selected from a sample of
NH3 cores associated with OH and H2O maser emission and with no or very faint
continuum emission. Our imaging of molecular line (including rotational
transitions of CH3CN and 3mm dust continuum emission revealed that these are
compact, massive, and hot molecular cores (HMCs), that is likely sites of
high-mass star formation prior to the appearance of UCHII regions. All three
sources turn out to be associated with molecular outflows from CO and/or HCO+
J=1--0 line imaging. In addition, velocity gradients of 10 -- 100 km/s per pc
in the innermost densest regions of the G23.01 and G28.87 HMCs are identified
along directions roughly perpendicular to the axes of the corresponding
outflows. All the results suggest that these cores might be rotating about the
outflow axis, although the contribution of rotation to gravitational
equilibrium of the HMCs appears to be negligible. Our analysis indicates that
the 3 HMCs are close to virial equilibrium due to turbulent pressure support.
Comparison with other similar objects where rotating toroids have been
identified so far shows that in our case rotation appears to be much less
prominent; this can be explained by the combined effect of unfavorable
projection, large distance, and limited angular resolution with the current
interferometers.


title: Topological Mott Insulators

abstract:
  We consider extended Hubbard models with repulsive interactions on a
Honeycomb lattice and the transitions from the semi-metal phase at half-filling
to Mott insulating phases. In particular, due to the frustrating nature of the
second-neighbor repulsive interactions, topological Mott phases displaying the
quantum Hall and the quantum spin Hall effects are found for spinless and
spinful fermion models, respectively. We present the mean-field phase diagram
and consider the effects of fluctuations within the random phase approximation
(RPA). Functional renormalization group analysis also show that these states
can be favored over the topologically trivial Mott insulating states.


title:
Study of $B_{c}^{-}$ ${\to}$ $J/{\psi}{\pi}^{-}$, ${\eta}_{c}{\pi}^{-}$
  Decays with QCD Factorization

abstract:
  The $B_{c}$ ${\to}$ $J/{\psi}{\pi}$, ${\eta}_{c}{\pi}$ decays are studied in
the scheme of the QCD factorization approach. The branching ratios are
calculated with the asymptotic distribution amplitude of the pion. The charm
quark mass effect is considered. We find that the mass effect on the branching
ratios is small.


title: Extended TQFT's and Quantum Gravity

abstract:
  This paper gives a definition of an extended topological quantum field theory
(TQFT) as a weak 2-functor Z: nCob_2 -> 2Vect, by analogy with the description
of a TQFT as a functor Z: nCob -> Vect. We also show how to obtain such a
theory from any finite group G. This theory is related to a topological gauge
theory, the Dijkgraaf-Witten model. To give this definition rigorously, we
first define a bicategory of cobordisms between cobordisms. We also give some
explicit description of a higher-categorical version of Vect, denoted 2Vect, a
bicategory of "2-vector spaces". Along the way, we prove several results
showing how to construct 2-vector spaces of "Vect-valued presheaves" on certain
kinds of groupoids. In particular, we use the case when these are groupoids
whose objects are connections, and whose morphisms are gauge transformations,
on the manifolds on which the extended TQFT is to be defined. On cobordisms
between these manifolds, we show how a construction of ``pullback and
pushforward'' of presheaves gives both the morphisms and 2-morphisms in 2Vect
for the extended TQFT, and that these satisfy the axioms for a weak 2-functor.
Finally, we discuss the motivation for this research in terms of Quantum
Gravity. If the results can be extended from a finite group G to a Lie group,
then for some choices of G this theory will recover an existing theory of
Euclidean quantum gravity in 3 dimensions. We suggest extensions of these ideas
which may be useful to further this connection and apply it in higher
dimensions.


title: Particle Tracking with a Thin Pixel Telescope

abstract:
  We report results on a tracking performance study performed using a beam
telescope made of 50 micron-thick CMOS pixel sensors on the 1.5 GeV electron
beam at the LBNL ALS.


title: Developments in finite Phan theory

abstract:
  This is a final report on finite Phan theory, a project that has been
concerned with a revision and generalisation of Phan's presentation results of
twisted Chevalley groups over finite fields with simply laced diagrams by
unitary subgroups of rank one and two. Finite Phan theory has been initiated on
request by Richard Lyons and Ronald Solomon in order to support their revision
of the classification of the finite simple groups.


title: On a two variable class of Bernstein-Szego measures

abstract:
  The one variable Bernstein-Szego theory for orthogonal polynomials on the
real line is extended to a class of two variable measures. The polynomials
orthonormal in the total degree ordering and the lexicographical ordering are
constructed and their recurrence coefficients discussed.


title:
Time-Loop Formalism for Irreversible Quantum Problems: Steady State
  Transport in Junctions with Asymmetric Dynamics

abstract:
  Non-unitary quantum mechanics has been used in the past to study
irreversibility, dissipation and decay in a variety of physical systems. In
this letter, we propose a general scheme to deal with systems governed by
non-Hermitian Hamiltonians. We argue that the Schwinger-Keldysh formalism gives
a natural description for those problems. To elucidate the method, we study a
simple model inspired by mesoscopic physics --an asymmetric junction. The
system is governed by a non-Hermitian Hamiltonian which captures essential
aspects of irreversibility.

categories: cond-mat.mes-hall hep-th physics.atom-ph quant-ph


title:
Notes on a paper of Tyagi and Holm: A new integral representation for
  the Riemann Zeta function

abstract:
  It is shown that a new series representation of Riemann s Zeta function
obtained by Tyagi and Holm leads to an interesting new recursion for Bernoulli
numbers of even index as well as new representations of, and infinite series
involving, Zeta functions of special (integer) argument.


title:
Characterization of the matrix whose norm is determined by its action on
  decreasing sequences:The exceptional cases

abstract:
  Let $A=(a_{j,k})_{j,k \ge 1}$ be a non-negative matrix. In this paper, we
characterize those $A$ for which $\|A\|_{\ell_p,\ell_q}$ are determined by
their actions on non-negative decreasing sequences, where one of $p$ and $q$ is
1 or $\infty$. The conditions forcing on $A$ are sufficient and they are also
necessary for non-negative finite matrices.


title:
Search for the Invisible Decay of $\jpsi$ in
  $\psi(2S)\to\pi+\pi^-J/\psi$

abstract:
  Using 14.0 million $\psi(2S) events collected with the BES-II detector, a
search for the decay of the $\jpsi$ to an invisible final state in $\psipto$ is
performed. The $\jpsi$ peak in the distribution of mass recoiling against the
$\pi^+\pi^-$ is used to tag $\psi$ invisible decay. No signal is found, and an
upper limit at the 90% confidence level is determined to be $1.2\times 10^{-2}$
for the ratio $\frac{{\cal B}(\jpsi\ar {invisible})}{{\cal
B}(\jpsi\ar\mu^+\mu^-)}$. This is the first search for $J/\psi$ decay to an
invisible final state.


title: K* production in Heavy Ion Collisions at RHIC

abstract:
  Study of resonances with their short life-times provides useful tools to
probe the properties of hot and dense matter produced in relativistic heavy ion
collisions. The high density and/or high temperature of the medium can modify
resonance properties such as mass and width. Therefore, measurement of these
properties can reveal important information about the evolution dynamics in
heavy ion collisions. We report the measurements of $K^{*}$ transverse
momentum($p_T$) spectra at mid-rapidity via its hadronic decay channel up to
intermediate $p_{T}$ of 2.9 GeV/c using the STAR detector in Au+Au and Cu+Cu
collisions at $\sqrt{s_{\mathrm{NN}}}$= 62.4 GeV and 200 GeV. These results are
compared to previously reported $K^{*}$ results from Au+Au collisions at RHIC.
Integrated yield ratios of $K^{*}/K$ and $K^{*}/\phi$ are used to understand
the rescattering and regeneration effects on $K^{*}$ production.


title: Low-Temperature Phase Boundary of dilute Lattice Spin Glasses

abstract:
  The thermal-to-percolative crossover exponent \phi, well-known for
ferromagnetic systems, is studied extensively for Edwards-Anderson spin
glasses. The scaling of defect energies are determined at the bond percolation
threshold p_c, using an improved algorithm. Simulations extend to system sizes
above N=10^8 in dimensions d=2,...,7. The results can be related to the
behavior of the transition temperature T_g (p-p_c)^\phi between the
paramagnetic and the glassy regime for p-> p_c. In three dimensions, where our
simulations predict \phi=1.127(5), this scaling form for T_g provides a rare
experimental test of predictions arising from the equilibrium theory of
low-temperature spin glasses. For dimension near and above the upper critical
dimension, the results provide a new challenge to reconcile mean-field theory
with finite-dimensional properties.


title:
Shear Thickening and Scaling of the Elastic Modulus in a Fractal
  Colloidal System with Attractive Interactions

abstract:
  Dilute oil dispersions of fractal carbon black particles with attractive Van
der Waals interactions display continuous shear thickening followed by shear
thinning at high shear rates. The shear thickening transition occurs at
$\dot\gamma_{c}\approx 10^{2}-10^{3}s^{-1}$ and is driven by hydrodynamic
breakup of clusters. Pre-shearing dispersions at shear rates
$\dot\gamma>\dot\gamma_{c}$ produces enhanced-modulus gels where $G' \sim
\sigma_{pre-shear}^{1.5-2}$ and is directly proportional to the residual stress
in the gel measured at a fixed sample age. The observed data can be accounted
for using a simple scaling model for the breakup of fractal clusters under
shear stress.


title: Graph rigidity, Cyclic Belief Propagation and Point Pattern Matching

abstract:
  A recent paper \cite{CaeCaeSchBar06} proposed a provably optimal, polynomial
time method for performing near-isometric point pattern matching by means of
exact probabilistic inference in a chordal graphical model. Their fundamental
result is that the chordal graph in question is shown to be globally rigid,
implying that exact inference provides the same matching solution as exact
inference in a complete graphical model. This implies that the algorithm is
optimal when there is no noise in the point patterns. In this paper, we present
a new graph which is also globally rigid but has an advantage over the graph
proposed in \cite{CaeCaeSchBar06}: its maximal clique size is smaller,
rendering inference significantly more efficient. However, our graph is not
chordal and thus standard Junction Tree algorithms cannot be directly applied.
Nevertheless, we show that loopy belief propagation in such a graph converges
to the optimal solution. This allows us to retain the optimality guarantee in
the noiseless case, while substantially reducing both memory requirements and
processing time. Our experimental results show that the accuracy of the
proposed solution is indistinguishable from that of \cite{CaeCaeSchBar06} when
there is noise in the point patterns.


title: A modular absolute bound condition for primitive association schemes

abstract:
  The well-known absolute bound condition for a primitive symmetric association
scheme (X,S) gives an upper bound for |X| in terms of |S| and the minimal
non-principal multiplicity of the scheme. In this paper we prove another upper
bounds for |X| for an arbitrary primitive scheme (X,S). They do not depend on
|S| but depend on some invariants of its adjacency algebra KS where K is an
algebraic number field or a finite field.


title:
Quantum Entangled Dark Solitons Formed by Ultracold Atoms in Optical
  Lattices

abstract:
  Inspired by experiments on Bose-Einstein condensates in optical lattices, we
study the quantum evolution of dark soliton initial conditions in the context
of the Bose-Hubbard Hamiltonian. An extensive set of quantum measures is
utilized in our analysis, including von Neumann and generalized quantum
entropies, quantum depletion, and the pair correlation function. We find that
quantum effects cause the soliton to fill in. Moreover, soliton-soliton
collisions become inelastic, in strong contrast to the predictions of
mean-field theory. These features show that the lifetime and collision
properties of dark solitons in optical lattices provide clear signals of
quantum effects.


title: The basis digraphs of p-schemes

abstract:
  It is proved that association schemes with bipartite basis graphs are exactly
2-schemes. This result follows from a characterization of p-schemes for an
arbitrary prime p in terms of basis digraphs.


title:
Addendum: Triton and hypertriton binding energies calculated from SU_6
  quark-model baryon-baryon interactions

abstract:
  Previously we calculated the binding energies of the triton and hypertriton,
using an SU_6 quark-model interaction derived from a resonating-group method of
two baryon clusters. In contrast to the previous calculations employing the
energy-dependent interaction kernel, we present new results using a
renormalized interaction, which is now energy independent and reserves all the
two-baryon data. The new binding energies are slightly smaller than the
previous values. In particular the triton binding energy turns out to be 8.14
MeV with a charge-dependence correction of the two-nucleon force, 190 keV,
being included. This indicates that about 350 keV is left for the energy which
is to be accounted for by three-body forces.


title:
Modeling Diffusive Dynamics in Adaptive Resolution Simulation of Liquid
  Water

abstract:
  We present a dual-resolution molecular dynamics (MD) simulation of liquid
water employing a recently introduced Adaptive Resolution Scheme (AdResS). The
spatially adaptive molecular resolution procedure allows for changing from a
coarse-grained to an all-atom representation and vice-versa on-the-fly. In
order to find the most appropriate coarse-grained water model to be employed
with AdResS we first study the accuracy of different coarse-grained water
models in reproducing the structural properties of the all-atom system.
Typically, coarse-grained molecular models have a higher diffusion constant
than the corresponding all-atom models due to the reduction in degrees of
freedom (DOFs) upon coarse-graining that eliminates the fluctuating forces
associated with those integrated-out molecular DOFs. Here, we introduce the
methodology to obtain the same diffusional dynamics across different
resolutions. We show that this approach leads to the correct description of
essential thermodynamic, structural and dynamical properties of liquid water at
ambient conditions.


title: On equivariant mirror symmetry for local P^2

abstract:
  We solve the problem of equivariant mirror symmetry for O(-3)->P^2 for the
(three) cases of one independent equivariant parameter. This gives a
decomposition of mirror symmetry for local P^2 into that of three subspaces,
each of which may be considered independently. Finally, we give a new
interpretation of mirror symmetry for O(k)+O(-2-k)->P^1.


title: Combinatorial Stokes formulas via minimal resolutions

abstract:
  We describe an explicit chain map from the standard resolution to the minimal
resolution for the finite cyclic group Z_k of order k. We then demonstrate how
such a chain map induces a "Z_k-combinatorial Stokes theorem", which in turn
implies "Dold's theorem" that there is no equivariant map from an n-connected
to an n-dimensional free Z_k-complex.
  Thus we build a combinatorial access road to problems in combinatorics and
discrete geometry that have previously been treated with methods from
equivariant topology. The special case k=2 for this is classical; it involves
Tucker's (1949) combinatorial lemma which implies the Borsuk-Ulam theorem, its
proof via chain complexes by Lefschetz (1949), the combinatorial Stokes formula
of Fan (1967), and Meunier's work (2006).


title: Doubly heavy baryon production at polarized photon collider

abstract:
  We study the inclusive production of doubly heavy baryon $\Xi_{cc}$ at
polarized photon collider. Our results show that proper choice of the initial
beam polarizations may increase the production rate of $\Xi_{cc}$ approximately
10%.


title:
Influence of a small perturbation on Poincare-Andronov operators with
  not well defined topological degree

abstract:
  Let $P_e\in C^0(R^n,R^n)$ be the Poincare-Andronov operator over period $T>0$
of the $T$-periodically perturbed autonomous system $x'=f(x)+e g(t,x,e),$ where
$e>0$ is small. Assuming that for $e=0$ this system has a $T$-periodic limit
cycle $x_0$ we evaluate the topological degree $d(I-P_e,U)$ of $I-P_e$ on an
open bounded set $U$ whose boundary contains $x_0([0,T])$ and does not contain
other fixed points of $P_0.$ We give an explicit formula connecting
$d(I-P_e,U)$ with topological indexes of zeros of the associated Malkin's
bifurcation function. The goal of the paper is to prove Mawhin's conjecture
which claims that $d(I-P_e,U)$ can be any integer in spite of the fact that the
measure of the set of fixed points of $P_0$ on $\partial U$ is zero.


title: High-sensitivity imaging with multi-mode twin beams

abstract:
  Twin entangled beams produced by single-pass parametric down-conversion (PDC)
offer the opportunity to detect weak amount of absorption with an improved
sensitivity with respect to standard techniques which make use of classical
light sources. We propose a differential measurement scheme which exploits the
spatial quantum correlation of type II PDC to image a weak amplitude object
with a sensitivity beyond the standard quantum limit imposed by shot-noise.


title: Coupled nanopillar waveguides: optical properties and applications

abstract:
  In this paper we review basic properties of coupled periodic and aperiodic
nanopillar waveguides. A coupled nanopillar waveguide consists of several rows
of periodically or aperiodically placed dielectric rods (pillars). In such a
waveguide, light confinement is due to the total internal reflection, while
guided modes dispersion is strongly affected by the waveguide structure. We
present a systematic analysis of the optical properties of coupled nanopillar
waveguides and discuss their possible applications for integrated optics.


title: Periodic solutions for a class of singulary perturbated systems

abstract:
  In this paper we provide conditions to ensure the existence, for $e>0$
sufficiently small, of periodic solutions of given period $T>0$ in a prescribed
domain $U$ for a class of singularly perturbed first order differential
systems. Here $e>0$ is the perturbation parameter. Our approach, based on the
topological degree theory and the averaging theory, permits to weaken the
conditions in [K.R. Schneider, Vibrational control of singularly perturbed
systems, in "Lectures Notes in Control and Information Science", 259, 397-408,
Springer, London, 2001, Theorem 2] under which the existence of periodic
solutions is proved.


title: Small parameter perturbations of nonlinear periodic systems

abstract:
  In this paper we consider a class of nonlinear periodic differential systems
perturbed by two nonlinear periodic terms with multiplicative different powers
of a small parameter $e>0$. For such a class of systems we provide conditions
which guarantee the existence of periodic solutions of given period $T>0$.
These conditions are expressed in terms of the behaviour on the boundary of an
open bounded set $U$ of $R^n$ of the solutions of suitably defined linearized
systems. The approach is based on the classical theory of the topological
degree for compact vector fields. An application to the existence of periodic
solutions to the van der Pol equation is also presented.


title:
A new approach in the theory of ordinary differential equations with
  small parameter

abstract:
  A topological degree based averaging principle has been proposed by J. Mawhin
in his PhD thesis [J. Mawhin, Le Probleme des Solutions Periodiques en
Mecanique non Lineaire, These de doctorat en sciences, Universite de Liege,
1969]. In the present paper we extend this result for the case when the
unperturbed system is nonlinear but possesses a set of T-periodic solutions
whose initial conditions constitute a boundary of some open set.


title: Non-Minimal Inflation after WMAP3

abstract:
  The Wilkinson Microwave Anisotropy Probe (WMAP) three year results are used
to constraint non-minimal inflation models. Two different non-minimally coupled
scalar field potentials are considered to calculate corresponding slow-roll
parameters of non-minimal inflation. The results of numerical analysis of
parameter space are compared with WMAP3 data to find appropriate new
constraints on the values of the non-minimal coupling. A detailed comparison of
our results with previous studies reveals the present status of the non-minimal
inflation model after WMAP3.


title: Motif-based communities in complex networks

abstract:
  Community definitions usually focus on edges, inside and between the
communities. However, the high density of edges within a community determines
correlations between nodes going beyond nearest-neighbours, and which are
indicated by the presence of motifs. We show how motifs can be used to define
general classes of nodes, including communities, by extending the mathematical
expression of Newman-Girvan modularity. We construct then a general framework
and apply it to some synthetic and real networks.


title:
Methods of topological degree theory in Malkin I. G. - Melnikov V. K.'s
  problems for periodically perturbed systems

abstract:
  A topological degree based averaging principle has been proposed by J. Mawhin
in his PhD thesis [J. Mawhin, Le Probleme des Solutions Periodiques en
Mecanique non Lineaire, These de doctorat en sciences, Universite de Liege,
1969]. In his thesis the author gives analogous topological degree versions of
classical bifurcation results due to I.G. Malkin and V.K. Melnikov, namely the
conditions for bifurcation of periodic solutions from families are expressed in
term of the topological degree of the bifurcation function. Moreover, the
topological index of bifurcated periodic solutions is evaluated over that
degree. A third part of the thesis is devoted to the rate the bifurcated
periodic solutions converge when the perturbation vanishes. The
differentiability of perturbed systems is not assumed.


title:
Higher Order Normalizations in the Generalized Photogravitational
  Restricted Three Body Problem with Poynting-Robertson Drag

abstract:
  Higher order normalizations are performed in the generalized
photogravitational restricted three body problem with Poynting-Robertson drag.
In this problem we have taken bigger primary as a source of radiation and
smaller primary as an oblate spheroid. Whittaker method is used to transform
the second order part of the Hamiltonian into the normal form. We have also
performed Birkhoff's normalization of the Hamiltonian. For this we have tilized
Henrard's method and expanded the coordinates of the infinitesimal body in
double D'Alembert series. We have found the values of first and second order
components. They are affected by radiation pressure, oblateness and P-R drag.
Finally we obtained the third order part of the Hamiltonian zero.
  Keywords:Higher Order Normalization, Generalized Photogravitational, RTBP,P-R
drag


title:
Domain of attraction of asymptotically stable periodic solutions
  obtained via averaging principle

abstract:
  In this paper we propose an approach to evaluate the domain of attraction of
asymptotically stable periodic solutions obtained via averaging principle
(second Bogolubov's theorem or Mel'nikov's method). We discuss also how this
result is extended in the case when the right hand part is nonsmooth.


title: The Lorentz force effect on the On-Off dynamo intermittency

abstract:
  An investigation of the dynamo instability close to the threshold produced by
an ABC forced flow is presented. We focus on the on-off intermittency behavior
of the dynamo and the counter-effect of the Lorentz force in the non-linear
stage of the dynamo. The Lorentz force drastically alters the statistics of the
turbulent fluctuations of the flow and reduces their amplitude. As a result
much longer burst (on-phases) are observed than what is expected based on the
amplitude of the fluctuations in the kinematic regime of the dynamo. For large
Reynolds numbers, the duration time of the ``On'' phase follows a power law
distribution, while for smaller Reynolds numbers the Lorentz force completely
kills the noise and the system transits from a chaotic state into a ``laminar''
time periodic flow. The behavior of the On-Off intermittency as the Reynolds
number is increased is also examined. The connections with dynamo experiments
and theoretical modeling are discussed.


title:
A sufficient condition for the linear stability of magnetohydrodynamic
  equilibria with field aligned incompressible flows

abstract:
  A sufficient condition for the linear stability of three dimensional
equilibria with incompressible flows parallel to the magnetic field is derived.
The condition involves physically interpretable terms related to the magnetic
shear and the flow shear.


title: Commutativity and ideals in algebraic crossed products

abstract:
  We investigate properties of commutative subrings and ideals in
non-commutative algebraic crossed products for actions by arbitrary groups. A
description of the commutant of the base coefficient subring in the crossed
product ring is given. Conditions for commutativity and maximal commutativity
of the commutant of the base subring are provided in terms of the action as
well as in terms of the intersection of ideals in the crossed product ring with
the base subring, specially taking into account both the case of base rings
without non-trivial zero-divisors and the case of base rings with non-trivial
zero-divisors.


title:
HMC algorithm for two-flavour lattice QCD: Schwarz-preconditioning with
  a one-dimensional domain decomposition

abstract:
  We study a variant of the Schwarz-preconditioned HMC algorithm. In contrast
to the original proposal of L\"uscher, we apply the domain decomposition in one
lattice direction only. This is sufficient to reduce the condition number of
the fermion matrix restricted to the domains compared with the full fermion
matrix. For the same linear extension of the domain, less links reside on the
boundaries of the domains. Therefore it becomes e.g. practical to iterate the
decomposition. We perform numerical tests for two degenerate flavours of Wilson
fermions. The standard Wilson gauge action at $\beta=5.6$ is used. The
performance of our implementation is compared with other recent studies using
various types of preconditioning.


title:
Invariant measures of Hamiltonian systems with prescribed asymptotic
  Maslov index

abstract:
  We study the properties of the asymptotic Maslov index of invariant measures
for time-periodic Hamiltonian systems on the cotangent bundle of a compact
manifold M. We show that if M has finite fundamental group and the Hamiltonian
satisfies some general growth assumptions on the momenta, the asymptotic Maslov
indices of periodic orbits are dense in the positive half line. Furthermore, if
the Hamiltonian is the Fenchel dual of an electro-magnetic Lagrangian, every
non-negative number r is the limit of the asymptotic Maslov indices of a
sequence of periodic orbits which converges narrowly to an invariant measure
with asymptotic Maslov index r. We discuss the existence of minimal ergodic
invariant measures with prescribed asymptotic Maslov index by the analogue of
Mather's theory of the beta function, the asymptotic Maslov index playing the
role of the rotation vector.


title:
Wheeler's Gravitomagnetism Revisited I: A Purely Lorentz-Compton
  Approach to Vector Gravitational Waves and Trio-Holes

abstract:
  A theory of vector gravitational waves is presented on the basis of an
additional gravitational field, recovering ideas that go back to H. A. Lorentz,
field that A. Wheeler called ``gravitomagnetism''. The theory is independent of
Einstein's General Relativity Theory, but is consistent with the
Einstein-Lorentz framework of Special Relativity, so that the resulting
equations are considered exact from the start, and not approximations valid for
velocities small compared with the speed of light. A simple model of mass
formation and presence of angular momentum started with a new type of
singularity, ``trio-holes'', is exhibited.


title: High-order accurate implicit methods for the pricing of barrier options

abstract:
  This paper deals with a high-order accurate implicit finite-difference
approach to the pricing of barrier options. In this way various types of
barrier options are priced, including barrier options paying rebates, and
options on dividend-paying-stocks. Moreover, the barriers may be monitored
either continuously or discretely. In addition to the high-order accuracy of
the scheme, and the stretching effect of the coordinate transformation, the
main feature of this approach lies on a probability-based optimal determination
of boundary conditions. This leads to much faster and accurate results when
compared with similar pricing approaches. The strength of the present scheme is
particularly demonstrated in the valuation of discretely monitored barrier
options where it yields values closest to those obtained from the only
semi-analytical valuation method available.


title: Casimir operators of Lie algebras with a nilpotent radical

abstract:
  We show that a Lie algebra having a nilpotent radical has a fundamental set
of invariants consisting of Casimir operators. We give a different proof of
this fact in the special and well-known case where the radical is abelian.


title: Symmetry properties of a nonlinear acoustics model

abstract:
  We give a classification into conjugacy classes of subalgebras of the
symmetry algebra generated by the Zabolotskaya-Khokhlov equation, and obtain
all similarity reductions of this equation into $(1+1)$-dimensional equations.
We thus show that Lie classical reduction approach may also give rise to more
general reduced equations as those expected from the direct method of Clarkson
and Kruskal. By transforming the determining system for the similarity
variables into the equivalent adjoint system of total differential equations,
similarity reductions to {\sc ode}s which are independent of the three
arbitrary functions defining the symmetries are also obtained. These results
are again compared with those obtained by the direct method of Clarkson and
Kruskal, by finding in particular equivalence transformations mapping some of
the reduced equations to each other. Various families of new exact solutions
are also derived.


title: The vector and axial vector current in Wilson ChPT

abstract:
  We construct the vector and axial vector currents in Wilson Chiral
Perturbation Theory (WChPT), the low-energy effective theory for lattice QCD
with Wilson fermions.
  Our construction is slightly different compared to ChPT in continuum QCD,
where the currents are essentially the (partially) conserved currents
associated with the chiral symmetries. In WChPT, due to explicit chiral
symmetry breaking at non-zero lattice spacing, there appear O(a) terms in the
expressions for the currents which do not stem from the effective action. In
addition, the finite renormalization of the currents needs to be taken into
account in order to properly match the currents of the effective theory.
  As an illustration we compute f_pi to one loop with the renormalized axial
vector current for a particular renormalization condition. It turns out that
for this particular condition some of the O(a) corrections are taken care of by
the renormalization.


title:
Strongly coupled large N spectrum of two matrices coupled via a
  Yang-Mills interaction

abstract:
  We consider the large N spectrum of the quantum mechanical hamiltonian of two
hermitean matrices coupled via a Yang-Mills interaction. In a framework where
one of the matrices is treated exactly and the other is treated as a creation
operator impurity, the difference equation associated with the Yang-Mills
interaction is derived and solved exactly for two impurities. In this case, the
full string tension corrected spectrum depends on two momenta. For a specific
value of one of these momenta, the spectrum has the same structure as that of
giant magnon bound states. States with general number of impurities are also
discussed.


title:
Localized reversible nanoscale phase separation in Pr_0.63Ca_0.37MnO_3
  single crystal using a scanning tunneling microscope tip

abstract:
  We report the destabilization of the charge ordered insulating (COI) state in
a localized region of Pr_0.63Ca_0.37MnO_3 single crystal by current injection
using a scanning tunneling microscope tip. This leads to controlled phase
separation and formation of localized metallic nanoislands in the COI matrix
which have been detected by local tunneling conductance mapping. The metallic
regions thus created persist even after reducing the injected current to lower
values. The original conductance state can be restored by injecting a current
of similar magnitude but of opposite polarity. We thus achieve reversible
nanoscale phase separation that gives rise to the possibility to "write, read,
and erase" nanosized conducting regions in an insulating matrix with high
spatial resolution.


title:
Elliptic functions and efficient control of Ising spin chains with
  unequal couplings

abstract:
  In this article, we study optimal control of dynamics in a linear chain of
three spin 1/2, weakly coupled with unequal Ising couplings. We address the
problem of time-optimal synthesis of multiple spin quantum coherences. We
derive time-optimal pulse sequence for creating a desired spin order by
computing geodesics on a sphere under a special metric. The solution to the
geodesic equation is related to the nonlinear oscillator equation and the
minimum time to create multiple spin order can be expressed in terms of an
elliptic integral. These techniques are used for efficient creation of multiple
spin coherences in Ising spin-chains with unequal couplings.


title: A note on quantum 3-manifold invariants and hyperbolic volume

abstract:
  We investigate the conjectural relations between the
Reshetikhin-Turaev-Witten quantum SU(2) invariants and the volume of hyperbolic
3-manifolds. Given a finite set of sufficiently large positive integers, say J,
we construct examples of closed hyperbolic 3-manifolds with the same invariants
at all levels in J and different volume.


title: 2-loop Quantum Yang-Mills Condensate as Dark Energy

abstract:
  In seeking a model solving the coincidence problem, the effective Yang-Mills
condensate (YMC) is an alternative candidate for dark energy. A study is made
for the model up to the 2-loop order of quantum corrections. It is found that,
like in the 1-loop model, for generic initial conditions during the radiation
era, there is always a desired tracking solution, yielding the current status
$\Omega_\Lambda \simeq 0.73$ and $\Omega_m \simeq 0.27$. As the time $t\to
\infty$ the dynamics is a stable attractor. Thus the model naturally solves the
coincidence problem of dark energy. Moreover, if YMC decays into matter, its
equation of state (EoS) crosses -1 and takes $w\sim -1.1$, as indicated by the
recent observations.


title:
The Method of the Description of Dynamics Nonequilibrium Systems within
  the Frames of the Classical Mechanics

abstract:
  Within the frames of the analytical mechanics the method of the description
of dynamics of nonequilibrium systems of potentially interacting elements is
develops. The method is based on an opportunity of representation of
nonequilibrium system by set of interacting equilibrium subsystems. The
equation of motion of interacting subsystems is found. Based on it the
Lagrange, Hamilton and Liouville equations for subsystems are obtained. The
expression of an entropy production is found. The way of a substantiation of
thermodynamics in the frames of classical mechanic is offered.


title:
Scattering of Noncommutative Waves and Solitons in a Supersymmetric
  Chiral Model in 2+1 Dimensions

abstract:
  Interactions of noncommutative waves and solitons in 2+1 dimensions can be
analyzed exactly for a supersymmetric and integrable U(n) chiral model
extending the Ward model. Using the Moyal-deformed dressing method in an
antichiral superspace, we construct explicit time-dependent solutions of its
noncommutative field equations by iteratively solving linear equations. The
approach is illustrated by presenting scattering configurations for two
noncommutative U(2) plane waves and for two noncommutative U(2) solitons as
well as by producing a noncommutative U(1) two-soliton bound state.


title: Equivalent metrics and compactifications

abstract:
  Let (X,d) be a metric space and m\in X. Suppose that \phi:X\times
X\to\mathbold{R} is a nonnegative symmetric function. We define a metric
d^{\phi,m} on X which is equivalent to d. If d^{\phi,m} is totally bounded, its
completion is a compactification of (X,d). As examples, we construct two
compactifications of (\mathhbold{R}^s,d_E), where d_E is the Euclidean metric
and s\geq 2.


title: Skeleton expansions for directed polymers in disordered media

abstract:
  Partial summations of perturbation expansions of the directed polymer in
disordered media (DPRM) enables one to represent the latter as skeleton
expansions in powers of the effective coupling constant $\Delta (t)$, which
corresponds to the binding state between two replicas in the replica field
theory of DPRM, and is equivalent to the binding state of a quantum particle in
an external $\delta $% -potential. The strong coupling phase is characterized
by the exponential dependence of $\Delta (t)$ on $t$, $\Delta (t)\sim \exp
(p_{c}t)$ with $% p_{c} $ being the binding energy of the particle. For
dimensions $d>2$ the strong coupling phase exists for $\Delta_{0}>\Delta
_{c}(d)$. We compute explicitly the mean-square displacement and the 2nd
cumulant of the free energy to the lowest order in powers of effective coupling
in $d=1$. We argue that the elimination of the terms $\exp (p_{c}t)$ in
skeleton expansions demands an additional partial summation of skeleton series.


title: Permutative categories, multicategories, and algebraic K-theory

abstract:
  We show that the $K$-theory construction of arXiv:math/0403403, which
preserves multiplicative structure, extends to a symmetric monoidal closed
bicomplete source category, with the multiplicative structure still preserved.
The source category of arXiv:math/0403403, whose objects are permutative
categories, maps fully and faithfully to the new source category, whose objects
are (based) multicategories.


title: Sorting and Selection with Random Costs

abstract:
  There is a growing body of work on sorting and selection in models other than
the unit-cost comparison model. This work is the first treatment of a natural
stochastic variant of the problem where the cost of comparing two elements is a
random variable. Each cost is chosen independently and is known to the
algorithm. In particular we consider the following three models: each cost is
chosen uniformly in the range $[0,1]$, each cost is 0 with some probability $p$
and 1 otherwise, or each cost is 1 with probability $p$ and infinite otherwise.
We present lower and upper bounds (optimal in most cases) for these problems.
We obtain our upper bounds by carefully designing algorithms to ensure that the
costs incurred at various stages are independent and using properties of random
partial orders when appropriate.


title: Special relativity in complex vector algebra

abstract:
  Many different mathematical languages have been invented to describe the
ideas of Einstein's special relativity. One of the most powerful languages is
the Minkowski space-time algebra of D. Hestenes. We discuss the ideas of
special relativity in a complex 4-dimensional algebra of observables, which is
algebraically isomorphic to the even subalgebra of Hestenes' space-time
algebra.


title:
On inverse scattering at high energies for the multidimensional Newton
  equation in electromagnetic field

abstract:
  We consider the multidimensional (nonrelativistic) Newton equation in a
static electromagnetic field $$\ddot x = F(x,\dot x), F(x,\dot x)=-\nabla
V(x)+B(x)\dot x, \dot x={dx\over dt}, x\in C^2(\R,\R^n),\eqno{(*)}$$ where $V
\in C^2(\R^n,\R),$ $B(x)$ is the $n\times n$ real antisymmetric matrix with
elements $B_{i,k}(x)$, $B_{i,k}\in C^1(\R^n,\R)$ (and $B$ satisfies the closure
condition), and $|\pa^{j_1}_xV(x)| +|\pa^{j_2}_xB_{i,k}(x)| \le \beta_{|j_1|}
(1+|x|)^{-(\alpha+|j_1|)}$ for $x\in \R^n,$ $1\le|j_1|\le 2,$ $0\le|j_2|\le 1$,
$|j_2|=|j_1|-1$, $i,k=1... n$ and some $\alpha > 1$. We give estimates and
asymptotics for scattering solutions and scattering data for the equation $(*)$
for the case of small angle scattering. We show that at high energies the
velocity valued component of the scattering operator uniquely determines the
X-ray transforms $P\nabla V$ and $PB_{i,k}$ (on sufficiently rich sets of
straight lines). Applying results on inversion of the X-ray transform $P$ we
obtain that for $n\ge 2$ the velocity valued component of the scattering
operator at high energies uniquely determines $(\nabla V,B)$. We also consider
the problem of recovering $(\nabla V,B)$ from our high energies asymptotics
found for the configuration valued component of the scattering operator.
Results of the present work were obtained by developing the inverse scattering
approach of [R. Novikov, 1999] for $(*)$ with $B\equiv 0$ and of [Jollivet,
2005] for the relativistic version of $(*)$. We emphasize that there is an
interesting difference in asymptotics for scattering solutions and scattering
data for $(*)$ on the one hand and for its relativistic version on the other.


title: An Optical Lattice Clock with Spin-polarized 87Sr Atoms

abstract:
  We present a new evaluation of an 87Sr optical lattice clock using spin
polarized atoms. The frequency of the 1S0-3P0 clock transition is found to be
429 228 004 229 873.6 Hz with a fractional accuracy of 2.6 10^{-15}, a value
that is comparable to the frequency difference between the various primary
standards throughout the world. This measurement is in excellent agreement with
a previous one of similar accuracy.


title: Boson-assisted tunneling in layered metals

abstract:
  A theory for boson-assisted tunneling via randomly distributed resonant
states in a layered metals is developed. As particular examples, we consider
the electron-phonon interaction and the interaction between localized and
conduction electrons. The theory is applied to explain a non-monotonic
variation of the out-plane resistivity with temperature observed in
quasi-two-dimensional metals.


title: Lagrangian curves on spectral curves of monopoles

abstract:
  We study Lagrangian points on smooth holomorphic curves in T${\mathbb P}^1$
equipped with a natural neutral K\"ahler structure, and prove that they must
form real curves. By virtue of the identification of T${\mathbb P}^1$ with the
space ${\mathbb L}({\mathbb E}^3)$ of oriented affine lines in Euclidean
3-space ${\mathbb E}^3$, these Lagrangian curves give rise to ruled surfaces in
${\mathbb E}^3$, which we prove have zero Gauss curvature.
  Each ruled surface is shown to be the tangent lines to a curve in ${\mathbb
E}^3$, called the edge of regression of the ruled surface. We give an
alternative characterization of these curves as the points in ${\mathbb E}^3$
where the number of oriented lines in the complex curve $\Sigma$ that pass
through the point is less than the degree of $\Sigma$. We then apply these
results to the spectral curves of certain monopoles and construct the ruled
surfaces and edges of regression generated by the Lagrangian curves.


title: Blazar Observations with VERITAS

abstract:
  The Very Energetic Radiation Imaging Telescope Array System (VERITAS) is an
array of four 12m diameter Imaging Atmospheric Cherenkov Technique (IACT)
telescopes operated at the base of Mt. Hopkins in southern Arizona. The
four-telescope experiment started operation in April, 2007. GeV and TeV
gamma-ray observations of blazars can be used to probe the structure and
composition of their jets, and to contribute to our understanding of how
supermassive black holes accrete matter. In this contribution, we present first
VERITAS blazar results obtained with three and four telescopes.


title: The Diverse Stellar Populations of the W3 Star Forming Complex

abstract:
  An 800 sq-arcmin mosaic image of the W3 star forming complex obtained with
the Chandra X-ray Observatory gives a valuable new view of the spatial
structure of its young stellar populations. The Chandra image reveals about
1300 faint X-ray sources, most of which are PMS stars in the cloud. Some, but
not all, of the high-mass stars producing hypercompact and ultracompact H II
(UCHII) regions are also seen, as reported in a previous study.
  The Chandra images reveal three dramatically different embedded stellar
populations. The W3 Main cluster extends over 7 pc with about 900 X-ray stars
in a nearly-spherical distribution centered on the well-studied UCHII regions
and high-mass protostars. The cluster surrounding the prototypical UCHII region
W3(OH) shows a much smaller (<0.6 pc), asymmetrical, and clumpy distribution of
about 50 PMS stars. The massive star ionizing the W3 North H II region is
completely isolated without any accompanying PMS stars. In W3 Main, the
inferred ages of the widely distributed PMS stars are significantly older than
the inferred ages of the central OB stars illuminating the UCHIIs. We suggest
that different formation mechanisms are necessary to explain the diversity of
the W3 stellar populations: cluster-wide gravitational collapse with delayed OB
star formation in W3 Main, collect-and-collapse triggering by shock fronts in
W3(OH), and a runaway O star or isolated massive star formation in W3 North.


title: On rational blow-downs in Heegaard-Floer homology

abstract:
  Motivated by a result of L.P. Roberts on rational blow-downs in
Heegaard-Floer homology, we study such operations along 3-manifolds that arise
as branched double covers of $S^{3}$ along several non-alternating, slice
knots.


title: Geometry of moving planes

abstract:
  The concept of number and its generalization has played a central role in the
development of mathematics over many centuries and many civilizations.
Noteworthy milestones in this long and arduous process were the developments of
the real and complex numbers which have achieved universal acceptance. Serious
attempts have been made at further extensions, such as Hamiltons quaternions,
Grassmann's exterior algebra and Clifford's geometric algebra. By examining the
geometry of moving planes, we show how new mathematics is within reach, if the
will to learn these powerful methods can be found.


title: Generalized Dolbeault sequences in parabolic geometry

abstract:
  In this paper, we show the existence of a sequence of invariant differential
operators on a particular homogeneous model $G/P$ of a Cartan geometry. The
first operator in this sequence can be locally identified with the Dirac
operator in $k$ Clifford variables, $D=(D_1,..., D_k)$, where $D_i=\sum_j
e_j\cdot \partial_{ij}: C^\infty((\R^n)^k,\S)\to C^\infty((\R^n)^k,\S)$. We
describe the structure of these sequences in case the dimension $n$ is odd. It
follows from the construction that all these operators are invariant with
respect to the action of the group $G$.
  These results are obtained by constructing homomorphisms of generalized Verma
modules, what are purely algebraic objects.


title: The Destiny of Universes After the Big Trip

abstract:
  The big trip can be describe with the help of the Wheeler-DeWitt wave
equation ${\hat H}\psi(w,a)=0$. The probability to find the universe after big
trip in the state with $w=w_0$ will be maximal if $\partial\psi(w,a)/\partial
w|_{w=w_0}=0$ for any values of the scale factor $a$. It is shown that this
will be the case if and only if $w_0=-1/3$. This fact allows one to suggest
that vast majority of universes in multiverse must be in this state after their
big trips.


title: Quantum communication complexity of block-composed functions

abstract:
  A major open problem in communication complexity is whether or not quantum
protocols can be exponentially more efficient than classical protocols on
_total_ Boolean functions in the two-party interactive model. The answer
appears to be ``No''. In 2002, Razborov proved this conjecture for so far the
most general class of functions
  F(x, y) = f(x_1 * y_1, x_2 * y_2, ..., x_n * y_n), where f is a_symmetric_
Boolean function on n Boolean inputs, and x_i, y_i are the i'th bit of x and y,
respectively. His elegant proof critically depends on the symmetry of f.
  We develop a lower-bound method that does not require symmetry and prove the
conjecture for a broader class of functions. Each of those functions F(x, y) is
obtained by what we call the ``block-composition'' of a ``building block'' g :
{0, 1}^k by {0, 1}^k --> {0, 1}, with an f : {0, 1}^n -->{0, 1}, such that
  F(x, y) = f(g(x_1, y_1), g(x_2, y_2), ..., g(x_n, y_n)), where x_i and y_i
are the i'th k-bit block of x and y, respectively.
  We show that as long as g itself is ``hard'' enough, its block-composition
with an_arbitrary_ f has polynomially related quantum and classical
communication complexities. Our approach gives an alternative proof for
Razborov's result (albeit with a slightly weaker parameter), and establishes
new quantum lower bounds. For example, when g is the Inner Product function for
k=\Omega(\log n), the_deterministic_ communication complexity of its
block-composition with_any_ f is asymptotically at most the quantum complexity
to the power of 7.


title: The opacity of grains in protoplanetary atmospheres

abstract:
  We have computed the size distribution of silicate grains in the outer
radiative region of the envelope of a protoplanet evolving according to the
scenario of Pollack et al. (1996). Our computation includes grain growth due to
Brownian motion and overtake of smaller grains by larger ones. We also include
the input of new grains due to the breakup of planetesimals in the atmosphere.
We follow the procedure of Podolak (2003), but have speeded it up
significantly. This allows us to test the sensitivity of the code to various
parameters. We have also made a more careful estimate of the resulting grain
opacity. We find that the grain opacity is of the order of $10^{-2}\
\mathrm{cm^2 g^{-1}}$ throughout most of the outer radiative zone as Hubickyj
et al. (2005) assumed for their low opacity case, but near the outer edge of
the envelope, the opacity can increase to $\sim{1} \mathrm{cm^2 g^{-1}}$. We
discuss the effect of this on the evolution of the models.


title:
Pseudo-scalar meson form factors with maximally twisted Wilson fermions
  at Nf = 2

abstract:
  We present preliminary results for various electroweak form factors of
pseudo-scalar mesons using the tree-level improved Symanzik gauge action and
the maximally twisted mass fermionic action with Nf = 2 dynamical flavors. Our
results, obtained for both light and heavy quark masses at a single lattice
spacing (a ~ 0.09 fm) and at a single lattice volume (V * T = 24**3 * 48),
exhibit a quite remarkable statistical precision thanks to the use of
all-to-all quark propagators computed with a stochastic method. Moreover very
low values of the four-momentum transfer are achieved by making use of twisted
boundary conditions on the valence quark fields. The mass dependence of the
pion charge radius is analyzed using Chiral Perturbation Theory, obtaining
clear evidence of relevant two-loop contributions. The universal Isgur-Wise
function is computed from heavy-to-heavy electromagnetic transitions and its
slope in the case of $u(d)$ spectator quarks is found to be rho(IW)**2 = 0.77
+/- 0.28, where the error is statistical only.


title: A survey of large N continuum phase transitions

abstract:
  The main focus of this talk is the physics of large N QCD on a continuum
torus. A cascade of phase transitions associated with the breaking of U(1)
symmetries will be discussed. The continuum Wilson loop as a function of its
area will be discussed along with its universality properties and the
associated double scaling limit. Some recent progress in twisted Eguchi-Kawai
is presented. Gauge field topology and $\theta$ vacuua are also discussed in
the context of large N gauge theories. Phase transitions in 2D large N
principal chiral models are compared with similar transitions in large $N$
gauge theories. Finally, connections to some topics in string theory and
gravity are briefly described.


title:
Elastic-like Collision of Gap Solitons in Bragg Gap Regions within
  Nonlocal Nonlinear Photonic Crystals

abstract:
  We analyze the existence, stability, and mobility of gap solitons in a
periodic photonic structure with nonlocal nonlinearity. Within the Bragg region
of band gaps, gap solitons exhibit better stability and higher mobility due to
the combinations of non-locality effect and the oscillation nature of Bloch
waves. Using linear stability analysis and calculating the Peierls-Nabarro
potentials, we demonstrate that gap solitons can revive a non-trivial
elastic-like collision even in the periodic systems with the help of nonlocal
nonlinearity. Such interesting behaviors of gap solitons in nonlocal nonlinear
photonic crystals are believed to be useful in optical switching devices.


title:
Design Considerations for the Next Generation of Atmospheric Imaging
  Cherenkov Telescopes

abstract:
  We estimate the limiting angular resolution and detection area for an array
of 3 large-aperture Imaging Atmospheric Cherenkov Telescopes. We consider an
idealized IACT system in order to understand the limitations imposed by the
intrinsic nature of the atmospheric showers and geometry of the detector
configuration. The idealization includes the assumptions of a perfect optical
system and the absence of the night sky background with the goal of finding the
optimum camera geometry and array configuration independent of detailed
assumptions about the telescope design.
  The showers are simulated using the ALTAI code for the altitude of 2700 m
corresponding to one of possible future sites for a new northern-hemisphere
array. The optimal design depends on the target energy range; for each energy
we vary both the cell length (telescope spacing) and the image processing
parameters in order to maximize the signal-to-noise ratio. We then present the
resulting values of the detection area and the angular resolution for this
energy dependent optimization. We discuss the dependence of these quantities on
the field of view of the telescopes and pixel size of the camera.


title: Counting Nodal Lines Which Touch the Boundary of an Analytic Domain

abstract:
  We consider the zeros on the boundary $\partial \Omega$ of a Neumann
eigenfunction $\phi_{\lambda}$ of a real analytic plane domain $\Omega$. We
prove that the number of its boundary zeros is $O (\lambda)$ where $-\Delta
\phi_{\lambda} = \lambda^2 \phi_{\lambda}$. We also prove that the number of
boundary critical points of either a Neumann or Dirichlet eigenfunction is
$O(\lambda)$. It follows that the number of nodal lines of $\phi_{\lambda}$
(components of the nodal set) which touch the boundary is of order $\lambda$.
This upper bound is of the same order of magnitude as the length of the total
nodal line, but is the square root of the Courant bound on the number of nodal
components in the interior. More generally, the results are proved for
piecewise analytic domains.


title: Representing Dehn twists with branched coverings

abstract:
  We show that any homologically non-trivial Dehn twist of a compact surface F
with boundary is the lifting of a half-twist in the braid group B_n, with
respect to a suitable branched covering p : F -> B^2. In particular, we allow
the surface to have disconnected boundary. As a consequence, any allowable
Lefschetz fibration on B^2 is a branched covering of B^2 x B^2.


title:
Transport Control of Eyring-Fluids along a Transversely-Corrugated
  Nanoannulus

abstract:
  The volume flow rates of Eyring-fluids inside the wavy-rough nanoannulus were
obtained analytically (up to the second order) by using the verified model and
boundary perturbation method. Our results show that the wavy-roughness could
enhance the flow rate especially for smaller forcing due to the larger
surface-to-volume ratio and slip-velocity effect. Meanwhile, the phase shift
between the outer and inner walls of nanoannuli could tune the transport of
Eyring-fluids either forward or backward when the wavy-roughness of a
nanoannulus is larger enough. Our results could be applied to the flow control
in nanofluidics as well as biofluidics.


title:
Regular reflection in self-similar potential flow and the sonic
  criterion

abstract:
  Reflection of a shock from a solid wedge is a classical problem in gas
dynamics. Depending on the parameters either a regular or a irregular
(Mach-type) reflection results. We construct regular reflection as an exact
self-similar solution for potential flow. For some upstream Mach numbers and
isentropic coefficients, a solution exists for all wedge angles allowed by the
sonic criterion. This demonstrates that, at least for potential flow, weaker
criteria are false.


title: Zipf's Law and Avoidance of Excessive Synonymy

abstract:
  Zipf's law states that if words of language are ranked in the order of
decreasing frequency in texts, the frequency of a word is inversely
proportional to its rank. It is very robust as an experimental observation, but
to date it escaped satisfactory theoretical explanation. We suggest that Zipf's
law may arise from the evolution of word semantics dominated by expansion of
meanings and competition of synonyms.


title: Fuzzy almost quadratic functions

abstract:
  We approximate a fuzzy almost quadratic function by a quadratic function in a
fuzzy sense. More precisely, we establish a fuzzy Hyers--Ulam--Rassias
stability of the quadratic functional equation $f(x+y)+f(x-y)=2f(x)+2f(y)$. Our
result can be regarded as a generalization of the stability phenomenon in the
framework of normed spaces. We also prove a generalized version of fuzzy
stability of the Pexiderized quadratic functional equation
$f(x+y)+f(x-y)=2g(x)+2h(y)$.


title: A Mazur--Ulam theorem in non-Archimedean normed spaces

abstract:
  The classical Mazur--Ulam theorem which states that every surjective isometry
between real normed spaces is affine is not valid for non-Archimedean normed
spaces. In this paper, we establish a Mazur--Ulam theorem in the
non-Archimedean strictly convex normed spaces.


title: Symmetry based Structure Entropy of Complex Networks

abstract:
  Precisely quantifying the heterogeneity or disorder of a network system is
very important and desired in studies of behavior and function of the network
system. Although many degree-based entropies have been proposed to measure the
heterogeneity of real networks, heterogeneity implicated in the structure of
networks can not be precisely quantified yet. Hence, we propose a new structure
entropy based on automorphism partition to precisely quantify the structural
heterogeneity of networks. Analysis of extreme cases shows that entropy based
on automorphism partition can quantify the structural heterogeneity of networks
more precisely than degree-based entropy. We also summarized symmetry and
heterogeneity statistics of many real networks, finding that real networks are
indeed more heterogenous in the view of automorphism partition than what have
been depicted under the measurement of degree based entropies; and that
structural heterogeneity is strongly negatively correlated to symmetry of real
networks.


title:
Simultaneous cooling of an artificial atom and its neighboring quantum
  system

abstract:
  We propose an approach for cooling both an artificial atom (e.g., a flux
qubit) and its neighboring quantum system, the latter modeled by either a
quantum two-level system or a quantum resonator. The flux qubit is cooled by
manipulating its states, following an inverse process of state population
inversion, and then the qubit is switched on to resonantly interact with the
neighboring quantum system. By repeating these steps, the two subsystems can be
simultaneously cooled. Our results show that this cooling is robust and
effective, irrespective of the chosen quantum systems connected to the qubit.


title: Storage of spin squeezing in a two-component Bose-Einstein condensate

abstract:
  Efficient control of spin squeezing in a two-component Bose-Einstein
Condensate is studied by rapidly turning-off the external field at a time that
maximal spin squeezing appears. We show that strong reduction of spin
fluctuation can be maintained in a nearly fixed direction for a long time. We
explain the underlying physics unambiguously, and present analytical
expressions of the maximal-squeezing time.


title:
Enhancement of flux pinning and high critical current density in
  graphite doped MgB2 superconductor

abstract:
  We report the synthesis and characterization of graphite (C) doped MgB2-xCx
(x = 0.0, 0.1, 0.2 and 0.3) samples. The crystal structure and microstructural
characterization have been investigated by x-ray diffractometer and
transmission electron microscopic (TEM) analysis. The superconducting
properties especially Jc and Hc2 have been measured by employing physical
property measurement system. We found that the graphite doping affects the
lattice parameters as well as the microstructure of MgB2 superconductor. In
case of optimally doped (x=0.1) sample, the critical current density at 5K
corresponds to 1.1 x 10^6 and 5.3 x 10^4 A/cm^2 for 3T and 5T fields
respectively. The upper critical field has been enhanced nearly two times after
doping. The flux pinning behavior has been investigated by flux pinning force
density curve and it reveals that the flux pinning behaviour has improved
significantly by doping. TEM micrographs show the graphite nanoparticles of
size ~5-10 nm which are invariably present in MgB2 grains. These nanoparticles
act as flux pinning centre and are responsible for enhancement of
superconducting properties of MgB2.


title:
Improvement of conversion efficiency of atom-molecule Bose-Einstein
  condensate

abstract:
  We investigate the stimulated Raman adiabatic passage in two-color
photoassociation for a atom-molecule Bose-Einstein condensate. By applying two
time-varying Guassian laser pulses that fulfill generalized two-photon
resonance condition, we obtain highly efficient atom-molecule conversion. The
efficiency depends on the free-bound detuning and the delay time between the
two pulses. By adjusting the parameters optimally, we achieve 92% conversion
efficiency.


title:
Stability of nodal quasi-particles in superconductors with coexisting
  orders

abstract:
  We establish a condition for the perturbative stability of zero energy nodal
points in the quasi-particle spectrum of superconductors in the presence of
coexisting \textit{commensurate} orders. The nodes are found to be stable if
the Hamiltonian is invariant under time reversal followed by a lattice
translation. The principle is demonstrated with a few examples. Some
experimental implications of various types of assumed order are discussed in
the context of the cuprate superconductors.


title: Reinforcement learning in market games

abstract:
  Financial markets investors are involved in many games -- they must interact
with other agents to achieve their goals. Among them are those directly
connected with their activity on markets but one cannot neglect other aspects
that influence human decisions and their performance as investors.
Distinguishing all subgames is usually beyond hope and resource consuming. In
this paper we study how investors facing many different games, gather
information and form their decision despite being unaware of the complete
structure of the game. To this end we apply reinforcement learning methods to
the Information Theory Model of Markets (ITMM). Following Mengel, we can try to
distinguish a class $\Gamma$ of games and possible actions (strategies)
$a^{i}_{m_{i}}$ for $i-$th agent. Any agent divides the whole class of games
into analogy subclasses she/he thinks are analogous and therefore adopts the
same strategy for a given subclass. The criteria for partitioning are based on
profit and costs analysis. The analogy classes and strategies are updated at
various stages through the process of learning. This line of research can be
continued in various directions.


title: Null Energy Condition and Dark Energy Models

abstract:
  Null Energy Condition (NEC) requires the equation of state (EoS) of the
universe $w_u$ satisfy $w_u\geq-1$, which implies, for instance in a universe
with matter and dark energy dominating
$w_u=w_m\Omega_m+w_{de}\Omega_{de}=w_{de}\Omega_{de}\geq-1$. In this paper we
study constraints on the dark energy models from the requirement of the NEC. We
will show that with $\Omega_{de}\sim0.7$, $w_{de}<-1$ at present epoch is
possible. However, NEC excludes the possibility of $w_{de}<-1$ forever as
happened in the Phantom model, but if $w_{de}<-1$ stays for a short period of
time as predicted in the Quintom theory NEC can be satisfied. We take three
examples of Quintom models of dark energy, namely the phenomenological EoS, the
two-scalar-field model and the single scalar model with a modified
Dirac-Born-Infeld (DBI) lagrangian to show how this happens.


title: Distributed MIMO receiver - Achievable rates and upper bounds

abstract:
  In this paper we investigate the achievable rate of a system that includes a
nomadic transmitter with several antennas, which is received by multiple
agents, exhibiting independent channel gains and additive circular-symmetric
complex Gaussian noise. In the nomadic regime, we assume that the agents do not
have any decoding ability. These agents process their channel observations and
forward them to the final destination through lossless links with a fixed
capacity. We propose new achievable rates based on elementary compression and
also on a Wyner-Ziv (CEO-like) processing, for both fast fading and block
fading channels, as well as for general discrete channels. The simpler two
agents scheme is solved, up to an implicit equation with a single variable.
Limiting the nomadic transmitter to a circular-symmetric complex Gaussian
signalling, new upper bounds are derived for both fast and block fading, based
on the vector version of the entropy power inequality. These bounds are then
compared to the achievable rates in several extreme scenarios. The asymptotic
setting with numbers of agents and transmitter's antennas taken to infinity is
analyzed. In addition, the upper bounds are analytically shown to be tight in
several examples, while numerical calculations reveal a rather small gap in a
finite $2\times2$ setting. The advantage of the Wyner-Ziv approach over
elementary compression is shown where only the former can achieve the full
diversity-multiplexing tradeoff. We also consider the non-nomadic setting, with
agents that can decode. Here we give an achievable rate, over fast fading
channel, which combines broadcast with dirty paper coding and the decentralized
reception, which was introduced for the nomadic setting.


title: The clustering coefficient and community structure of bipartite networks

abstract:
  Many real-world networks display a natural bipartite structure. It is
necessary and important to study the bipartite networks by using the bipartite
structure of the data. Here we propose a modification of the clustering
coefficient given by the fraction of cycles with size four in bipartite
networks. Then we compare the two definitions in a special graph, and the
results show that the modification one is better to character the network. Next
we define a edge-clustering coefficient of bipartite networks to detect the
community structure in original bipartite networks.


title:
Pion and kaon production in central Pb+Pb collisions at 20A and 30A GeV:
  Evidence for the onset of deconfinement

abstract:
  Results on charged pion and kaon production in central Pb+Pb collisions at
20A and 30A GeV are presented and compared to data at lower and higher
energies. A rapid change of the energy dependence is observed around 30A GeV
for the yields of pions and kaons as well as for the shape of the transverse
mass spectra. The change is compatible with the prediction that the threshold
for production of a state of deconfined matter at the early stage of the
collisions is located at low SPS energies.


title:
Precise measurements of electron and hole g-factors of single quantum
  dots by using nuclear field

abstract:
  We demonstrated the cancellation of the external magnetic field by the
nuclear field at one edge of the nuclear polarization bistability in single
InAlAs quantum dots. The cancellation for the electron Zeeman splitting gives
the precise value of the hole g-factor. By combining with the exciton g-factor
that is obtained from the Zeeman splitting for linearly polarized excitation,
the magnitude and sign of the electron and hole g-factors in the growth
direction are evaluated.


title: Magnetic Strings in Einstein-Born-Infeld-Dilaton Gravity

abstract:
  A class of spinning magnetic string in 4-dimensional Einstein-dilaton gravity
with Liouville type potential which produces a longitudinal nonlinear
electromagnetic field is presented. These solutions have no curvature
singularity and no horizon, but have a conic geometry. In these spacetimes,
when the rotation parameter does not vanish, there exists an electric field,
and therefore the spinning string has a net electric charge which is
proportional to the rotation parameter. Although the asymptotic behavior of
these solutions are neither flat nor (A)dS, we calculate the conserved
quantities of these solutions by using the counterterm method. We also
generalize these four-dimensional solutions to the case of $(n+1)$-dimensional
rotating solutions with $k\leq[n/2]$ rotation parameters, and calculate the
conserved quantities and electric charge of them.


title:
On Isomorphism Classes and Invariants of Low Dimensional Complex
  Filiform Leibniz Algebras (PART 1)

abstract:
  The paper aims to investigate the classification problem of low dimensional
complex none Lie filiform Leibniz algebras. There are two sources to get
classification of filiform Leibniz algebras. The first of them is the naturally
graded none Lie filiform Leibniz algebras and the another one is the naturally
graded filiform Lie algebras. Here we do consider Leibniz algebras appearing
from the naturally graded none Lie filiform Leibniz algebras. This class can be
splited into two subclasses. However, isomorphisms within each class there were
not investigated. Before U.D.Bekbaev and I.S.Rakhimov suggested an approach to
the isomorphism problem in terms of invariants. This paper presents an
implementation of their result in low dimensional cases. Here we give the
complete classification of complex none Lie filiform Leibniz algebras in
dimensions at most 8 from the first class of the above mentioned result and
give a hypothetic formula for the number of isomorphism classes in finite
dimensional case.


title: A canonical bundle formular of projective Lagrangian fibrations

abstract:
  We classify singular fibres of a projective Lagrangian fibration over
codimension one points. As an application, we obtain a canonical bundle formula
for a projective Lagrangian fibration over a smooth manifold.


title: Bottom Baryons

abstract:
  Recently CDF and D0 collaborations observed several bottom baryons. In this
work we perform a systematic study of the masses of bottom baryons up to
$1/m_Q$ in the framework of heavy quark effective field theory (HQET) using the
QCD sum rule approach. The extracted chromo-magnetic splitting between the
bottom baryon heavy doublet agrees well with the experimental data.


title:
Modeling Lepton-Nucleon Inelastic Scattering from High to Low Momentum
  Transfer

abstract:
  We present a model for inclusive charged lepton-nucleon and
(anti)neutrino-nucleon cross sections at momentum transfer squared, $Q^2$,
$\sim1 {\rm GeV}^2$. We quantify the impact of existing low-Q charged-lepton
deep-inelastic scattering (DIS) data on effects due to high-twist operators and
on the extraction of parton distribution functions (PDFs). No evidence is found
for twist-6 contributions to structure functions (SF), and for a twist-4 term
in the logitudinal SF at $x\gtrsim0.1$. We find that DIS data are consistent
with the NNLO QCD approximation with the target mass and phenomenological high
twist corrections. For $Q^2<1 {\rm GeV}^2$, we extend extrapolation of the
operator product expansion, preserving the low-$Q$ current-conservation
theorems. The procedure yields a good description of data down to $Q^2\sim 0.5
{\rm GeV}^2$. An updated set of PDFs with reduced uncertainty and applicable
down to small momentum transfers in the lepton-nucleon scattering is obtained.