title:
The damped Pinney equation and its applications to dissipative quantum
  mechanics

abstract:
  The work considers the damped Pinney equation, defined as the model arising
when a linear in velocity damping term is included in the Pinney equation. In
the general case the resulting equation does not admit Lie point symmetries or
is reducible to a simpler form by any obvious coordinate transformation. In
this context the method of Kuzmak-Luke is applied to derive a perturbation
solution, for weak damping and slow time-dependence of the frequency function.
The perturbative and numerical solutions are shown to be in good agreement. The
results are applied to examine the time-evolution of Gaussian shaped
wave-functions in the Kostin formulation of dissipative quantum mechanics.


title:
Distribution of Time-Energy Entanglement over 100 km fiber using
  superconducting single-photon detectors

abstract:
  In this letter, we report an experimental realization of distributing
entangled photon pairs over 100 km of dispersion-shifted fiber. In the
experiment, we used a periodically poled lithium niobate waveguide to generate
the time-energy entanglement and superconducting single-photon detectors to
detect the photon pairs after 100 km. We also demonstrate that the distributed
photon pairs can still be useful for quantum key distribution and other quantum
communication tasks.


title: Hierarchies of Geometric Entanglement

abstract:
  We introduce a class of generalized geometric measures of entanglement. For
pure quantum states of $N$ elementary subsystems, they are defined as the
distances from the sets of $K$-separable states ($K=2,...,N$). The entire set
of generalized geometric measures provides a quantification and hierarchical
ordering of the different bipartite and multipartite components of the global
geometric entanglement, and allows to discriminate among the different
contributions. The extended measures are applied to the study of entanglement
in different classes of $N$-qubit pure states. These classes include $W$ and
$GHZ$ states, and their symmetric superpositions; symmetric multi-magnon
states; cluster states; and, finally, asymmetric generalized $W$-like
superposition states. We discuss in detail a general method for the explicit
evaluation of the multipartite components of geometric entanglement, and we
show that the entire set of geometric measures establishes an ordering among
the different types of bipartite and multipartite entanglement. In particular,
it determines a consistent hierarchy between $GHZ$ and $W$ states, clarifying
the original result of Wei and Goldbart that $W$ states possess a larger global
entanglement than $GHZ$ states. Furthermore, we show that all multipartite
components of geometric entanglement in symmetric states obey a property of
self-similarity and scale invariance with the total number of qubits and the
number of qubits per party.

categories: quant-ph cond-mat.other hep-th math-ph math.MP


title: Mass Screening in Modified Gravity

abstract:
  Models of modified gravity introduce extra degrees of freedom, which for
consistency with the data, should be suppressed at observable scales. In the
models that share properties of massive gravity such a suppression is due to
nonlinear interactions: An isolated massive astrophysical object creates a halo
of a nonzero curvature around it, shielding its vicinity from the influence of
the extra degrees of freedom. We emphasize that the very same halo leads to a
screening of the gravitational mass of the object, as seen by an observer
beyond the halo. We discuss the case when the screening could be very
significant and may rule out, or render the models observationally interesting.


title: On the difference of partial theta functions

abstract:
  Sums of the form add((-1)^n q^(n(n-1)/2) x^n, n>=0) are called partial theta
functions. In his lost notebook, Ramanujan recorded many identities for those
functions. In 2003, Warnaar found an elegant formula for a sum of two partial
theta functions. Subsequently, Andrews and Warnaar established a similar result
for the product of two partial theta functions. In this note, I discuss the
relation between the Andrews-Warnaar identity and the (1986) product formula
due to Gasper and Rahman. I employ nonterminating extension of Sears-Carlitz
transformation for 3\phi_2 to provide a new elegant proof for a companion
identity for the difference of two partial theta series. This difference
formula first appeared in the work of Schilling-Warnaar (2002). Finally, I show
that Schilling-Warnnar (2002) and Warnaar (2003) formulas are, in fact,
equivalent.


title: On Riesz Means of Eigenvalues

abstract:
  In this article we prove the equivalence of certain inequalities for Riesz
means of eigenvalues of the Dirichlet Laplacian with a classical inequality of
Kac. Connections are made via integral transforms including those of Laplace,
Legendre, Weyl, and Mellin, and the Riemann-Liouville fractional transform. We
also prove new universal eigenvalue inequalities and monotonicity principles
for Dirichlet Laplacians as well as certain Schr\"odinger operators. At the
heart of these inequalities are calculations of commutators of operators, sum
rules, and monotonic properties of Riesz means. In the course of developing
these inequalities we prove new bounds for the partition function and the
spectral zeta function (cf. Corollaries 3.5-3.7) and conjecture about
additional bounds.


title: Binary Collisions and the Slingshot Effect

abstract:
  We derive the equations for the gravity assist manoeuvre in the general 2D
case without the constraints of circular planetary orbits or widely different
masses as assumed by Broucke, and obtain the slingshot conditions and maximum
energy gain for arbitrary mass ratios of two colliding rigid bodies. Using the
geometric view developed in an earlier paper by the authors the possible
trajectories are computed for both attractive or repulsive interactions
yielding a further insight on the slingshot mechanics and its parametrization.
The general slingshot manoeuvre for arbitrary masses is explained as a
particular case of the possible outcomes of attractive or repulsive binary
collisions, and the correlation between asymptotic information and orbital
parameters is obtained in general.


title: Does Probability become Fuzzy in Small Regions of Spacetime?

abstract:
  In a recent paper, Buniy et al. have argued that a possible discretization of
spacetime leads to an unavoidable discretization of the state space of quantum
mechanics. In this paper, we show that this conclusion is not limited to
quantum theory: in any classical, quantum, or more general probabilistic
theory, states (i.e. probabilities or corresponding amplitudes) become discrete
or fuzzy for observers, as long as time evolution is reversible and entropy is
locally bounded.
  Specifically, we show that the Bekenstein bound suggests that probabilities
in small closed regions of space carry an uncertainty inversely proportional to
the the square root of the system's effective radius and energy.


title:
Exact solution of the six-vertex model with domain wall boundary
  conditions. Ferroelectric phase

abstract:
  This is a continuation of the paper [4] of Bleher and Fokin, in which the
large $n$ asymptotics is obtained for the partition function $Z_n$ of the
six-vertex model with domain wall boundary conditions in the disordered phase.
In the present paper we obtain the large $n$ asymptotics of $Z_n$ in the
ferroelectric phase. We prove that for any $\ep>0$, as $n\to\infty$,
$Z_n=CG^nF^{n^2}[1+O(e^{-n^{1-\ep}})]$, and we find the exact value of the
constants $C,G$ and $F$. The proof is based on the large $n$ asymptotics for
the underlying discrete orthogonal polynomials and on the Toda equation for the
tau-function.


title: On the role of Convexity in Isoperimetry, Spectral-Gap and Concentration

abstract:
  We show that for convex domains in Euclidean space, Cheeger's isoperimetric
inequality, spectral gap of the Neumann Laplacian, exponential concentration of
Lipschitz functions, and the a-priori weakest requirement that Lipschitz
functions have \emph{arbitrarily slow} uniform tail-decay, are all
quantitatively equivalent (to within universal constants, independent of the
dimension). This substantially extends previous results of Maz'ya, Cheeger,
Gromov--Milman, Buser and Ledoux. As an application, we conclude a sharp
quantitative stability result for the spectral gap of convex domains under
convex perturbations which preserve volume (up to constants) and under maps
which are ``on-average'' Lipschitz. We also provide a new characterization (up
to constants) of the spectral gap of a convex domain, as one over the square of
the average distance from the ``worst'' subset having half the measure of the
domain. In addition, we easily recover and extend many previously known lower
bounds on the spectral gap of convex domains, due to Payne--Weinberger,
Li--Yau, Kannan--Lov\'asz--Simonovits, Bobkov and Sodin. The proof involves
estimates on the diffusion semi-group following Bakry--Ledoux and a result from
Riemannian Geometry on the concavity of the isoperimetric profile. Our results
extend to the more general setting of Riemannian manifolds with density which
satisfy the $CD(0,\infty)$ curvature-dimension condition of Bakry-\'Emery.


title: Inflationary dynamics for matrix eigenvalue problems

abstract:
  Many fields of science and engineering require finding eigenvalues and
eigenvectors of large matrices. The solutions can represent oscillatory modes
of a bridge, a violin, the disposition of electrons around an atom or molecule,
the acoustic modes of a concert hall, or hundreds of other physical quantities.
Often only the few eigenpairs with the lowest or highest frequency (extremal
solutions) are needed. Methods that have been developed over the past 60 years
to solve such problems include the Lanczos [1,2] algorithm, Jacobi-Davidson
techniques [3], and the conjugate gradient method [4]. Here we present a way to
solve the extremal eigenvalue/eigenvector problem, turning it into a nonlinear
classical mechanical system with a modified Lagrangian constraint. The
constraint induces exponential inflationary growth of the desired extremal
solutions.


title: Twisted planes

abstract:
  Let k be a commutative ring. We find and characterize a new family of twisted
planes (i. e. associative unitary k-algebra structures on the k-module k[X,Y],
having k[X] and and k[Y] as subalgebras).Similar results are obtained for the
k-module of two variables power series k[[X,Y]].


title: Interaction matrix element fluctuations in quantum dots

abstract:
  In the Coulomb blockade regime of a ballistic quantum dot, the distribution
of conductance peak spacings is well known to be incorrectly predicted by a
single-particle picture; instead, matrix element fluctuations of the residual
electronic interaction need to be taken into account. In the normalized
random-wave model, valid in the semiclassical limit where the number of
electrons in the dot becomes large, we obtain analytic expressions for the
fluctuations of two-body and one-body matrix elements. However, these
fluctuations may be too small to explain low-temperature experimental data. We
have examined matrix element fluctuations in realistic chaotic geometries, and
shown that at energies of experimental interest these fluctuations generically
exceed by a factor of about 3-4 the predictions of the random wave model. Even
larger fluctuations occur in geometries with a mixed chaotic-regular phase
space. These results may allow for much better agreement between the
Hartree-Fock picture and experiment. Among other findings, we show that the
distribution of interaction matrix elements is strongly non-Gaussian in the
parameter range of experimental interest, even in the random wave model. We
also find that the enhanced fluctuations in realistic geometries cannot be
computed using a leading-order semiclassical approach, but may be understood in
terms of short-time dynamics.


title: Error-Correction of Multidimensional Bursts

abstract:
  In this paper we present several constructions to generate codes for
correcting a multidimensional cluster-error. The goal is to correct a
cluster-error whose shape can be a box-error, a Lee sphere error, or an error
with an arbitrary shape. Our codes have very low redundancy, close to optimal,
and large range of parameters of arrays and clusters. Our main results are
summarized as follows: 1) A construction of two-dimensional codes capable to
correct a rectangular-error with considerably more flexible parameters from
previously known constructions. Another advantage of this construction is that
it is easily generalized for D dimensions. 2) A novel method based on D
colorings of the D-dimensional space for constructing D-dimensional codes
correcting D-dimensional cluster-error of various shapes. This method is
applied efficiently to correct a D-dimensional cluster error of parameters not
covered efficiently by previous onstructions. 3) A transformation of the
D-dimensional space into another D-dimensional space such that a D-dimensional
Lee sphere is transformed into a shape located in a D-dimensional box of a
relatively small size. We use the previous constructions to correct a
D-dimensional error whose shape is a D-dimensional Lee sphere. 4) Applying the
coloring method to correct more efficiently a two-dimensional error whose shape
is a Lee sphere. The D-dimensional case is also discussed. 5) A construction of
one-dimensional codes capable to correct a burst-error of length b in which the
number of erroneous positions is relatively small compared to b. This
construction is generalized for D-dimensional codes. 6) Applying the
constructions correcting a Lee sphere error and a cluster-error with small
number of erroneous positions, to correct an arbitrary cluster-error.


title:
Ambiguities of neutrino(antineutrino) scattering on the nucleon due to
  the uncertainties of relevant strangeness form factors

abstract:
  Strange quark contributions to neutrino(antineutrino) scattering are
investigated on the nucleon level in the quasi-elastic region. The incident
energy range between 500 MeV and 1.0 GeV is used for the scattering. All of the
physical observable by the scattering are investigated within available
experimental and theoretical results for the strangeness form factors of the
nucleon. In specific, a newly combined data of parity violating electron
scattering and neutrino scattering is exploited. Feasible quantities to be
explored for the strangeness contents are discussed for the application to
neutrino-nucleus scattering.


title: Electron impact excitations of S2 molecules

abstract:
  Low-energy electron impact excitations of S_2 molecules are studied using the
fixed-bond R-matrix method based on state-averaged complete active space SCF
orbitals. Integral cross sections are calculated for elastic electron collision
as well as impact excitation of the 7 lowest excited electronic states. Also,
differential cross sections are obtained for elastic collision and excitation
of the a^1 Delta_g, b^1 Sigma_g^+ and B^3 Sigma_u^- states. The integrated
cross section of optically allowed excitation of the B^3 Sigma_u^- state agrees
reasonably well with the available theoretical result.


title: Digital Ecosystems: Optimisation by a Distributed Intelligence

abstract:
  Can intelligence optimise Digital Ecosystems? How could a distributed
intelligence interact with the ecosystem dynamics? Can the software components
that are part of genetic selection be intelligent in themselves, as in an
adaptive technology? We consider the effect of a distributed intelligence
mechanism on the evolutionary and ecological dynamics of our Digital Ecosystem,
which is the digital counterpart of a biological ecosystem for evolving
software services in a distributed network. We investigate Neural Networks and
Support Vector Machine for the learning based pattern recognition functionality
of our distributed intelligence. Simulation results imply that the Digital
Ecosystem performs better with the application of a distributed intelligence,
marginally more effectively when powered by Support Vector Machine than Neural
Networks, and suggest that it can contribute to optimising the operation of our
Digital Ecosystem.


title: Dark matter halo creation in moving barrier models

abstract:
  In hierarchical models, the time derivative of the halo mass function may be
thought of as the difference of two terms - a creation term, which describes
the increase in the number of haloes of mass m from mergers of less massive
objects, and a destruction term, which describes the decrease in the number of
m-haloes as these merge with other haloes, creating more massive haloes as a
result. In models where haloes form from a spherical collapse, the distribution
of halo creation times can be estimated from the same formalism which is used
to estimate halo abundances: the constant-barrier excursion-set approach. In
the excursion set approach, moving, rather than constant-barriers, are
necessary for estimating halo abundances when the collapse is triaxial. We show
how the corresponding estimates are modified by providing analytic estimates of
the creation rate for a wide range of halo masses. We then show that these
moving-barrier based predictions are in better agreement with measurements in
numerical simulations than are the corresponding predictions of the spherical
collapse model. These results should be useful for studies of merger-driven
star-formation rates and AGN activity. We also present a similar study of
creation of haloes conditioned on belonging to an object of a certain mass
today, and reach similar conclusions - the moving barrier based estimates are
in substantially better agreement with the simulations. This part of the study
may be useful for understanding the tendency for the oldest stars to exist in
the most massive objects.


title: Digital Ecosystems: Stability of Evolving Agent Populations

abstract:
  Stability is perhaps one of the most desirable features of any engineered
system, given the importance of being able to predict its response to various
environmental conditions prior to actual deployment. Engineered systems are
becoming ever more complex, approaching the same levels of biological
ecosystems, and so their stability becomes ever more important, but taking on
more and more differential dynamics can make stability an ever more elusive
property. The Chli-DeWilde definition of stability views a Multi-Agent System
as a discrete time Markov chain with potentially unknown transition
probabilities. With a Multi-Agent System being considered stable when its
state, a stochastic process, has converged to an equilibrium distribution,
because stability of a system can be understood intuitively as exhibiting
bounded behaviour. We investigate an extension to include Multi-Agent Systems
with evolutionary dynamics, focusing on the evolving agent populations of our
Digital Ecosystem. We then built upon this to construct an entropy-based
definition for the degree of instability (entropy of the limit probabilities),
which was later used to perform a stability analysis. The Digital Ecosystem is
considered to investigate the stability of an evolving agent population through
simulations, for which the results were consistent with the original
Chli-DeWilde definition.


title: Digital Ecosystems: Evolving Service-Oriented Architectures

abstract:
  We view Digital Ecosystems to be the digital counterparts of biological
ecosystems, exploiting the self-organising properties of biological ecosystems,
which are considered to be robust, self-organising and scalable architectures
that can automatically solve complex, dynamic problems. Digital Ecosystems are
a novel optimisation technique where the optimisation works at two levels: a
first optimisation, migration of agents (representing services) which are
distributed in a decentralised peer-to-peer network, operating continuously in
time; this process feeds a second optimisation based on evolutionary computing
that operates locally on single peers and is aimed at finding solutions to
satisfy locally relevant constraints. We created an Ecosystem-Oriented
Architecture of Digital Ecosystems by extending Service-Oriented Architectures
with distributed evolutionary computing, allowing services to recombine and
evolve over time, constantly seeking to improve their effectiveness for the
user base. Individuals within our Digital Ecosystem will be applications
(groups of services), created in response to user requests by using
evolutionary optimisation to aggregate the services. These individuals will
migrate through the Digital Ecosystem and adapt to find niches where they are
useful in fulfilling other user requests for applications. Simulation results
imply that the Digital Ecosystem performs better at large scales than a
comparable Service-Oriented Architecture, suggesting that incorporating ideas
from theoretical ecology can contribute to useful self-organising properties in
digital ecosystems.


title: On the Monotonicity of the Generalized Marcum and Nuttall Q-Functions

abstract:
  Monotonicity criteria are established for the generalized Marcum Q-function,
$\emph{Q}_{M}$, the standard Nuttall Q-function, $\emph{Q}_{M,N}$, and the
normalized Nuttall Q-function, $\mathcal{Q}_{M,N}$, with respect to their real
order indices M,N. Besides, closed-form expressions are derived for the
computation of the standard and normalized Nuttall Q-functions for the case
when M,N are odd multiples of 0.5 and $M\geq N$. By exploiting these results,
novel upper and lower bounds for $\emph{Q}_{M,N}$ and $\mathcal{Q}_{M,N}$ are
proposed. Furthermore, specific tight upper and lower bounds for
$\emph{Q}_{M}$, previously reported in the literature, are extended for real
values of M. The offered theoretical results can be efficiently applied in the
study of digital communications over fading channels, in the
information-theoretic analysis of multiple-input multiple-output systems and in
the description of stochastic processes in probability theory, among others.


title:
Turbulent ${\alpha}$-effect in twisted magnetic flux tubes dynamos in
  Riemannian space

abstract:
  Analytical solution of first order torsion ${\alpha}$-effect in twisted
magnetic flux tubes representing a flux tube dynamo in Riemannian space is
presented. Toroidal and poloidal component of the magnetic field decays as
$r^{-1}$, while grow exponentially in time. The rate of speed of the helical
dynamo depends upon the value of Frenet curvature of the tube. The $\alpha$
factor possesses a fundamental contribution from constant torsion tube
approximation. It is also assumed that the curvature of the magnetic axis of
the tube is constant. Though ${\alpha}$-effect dynamo equations are rather more
complex in Riemann flux tube coordinates, a simple solution assuming force-free
magnetic fields is shown to be possible. Dynamo solutions are possible if the
dynamo action is able to change the signs of torsion and curvature of the
dynamo flux tube simultaneously.


title:
Current and fluctuation in a two-state stochastic system under
  non-adiabatic periodic perturbation

abstract:
  We calculate a current and its fluctuation in a two-state stochastic system
under a periodic perturbation. The system could be interpreted as a channel on
a cell surface or a single Michaelis-Menten catalyzing enzyme. It has been
shown that the periodic perturbation induces so-called pump current, and the
pump current and its fluctuation are calculated with the aid of the geometrical
phase interpretation. We give a simple calculation recipe for the statistics of
the current, especially in a non-adiabatic case. The calculation scheme is
based on the non-adiabatic geometrical phase interpretation. Using the Floquet
theory, the total current and its fluctuation are calculated, and it is
revealed that the average of the current shows a stochastic-resonance-like
behavior. In contrast, the fluctuation of the current does not show such
behavior.


title: Orthogonal Polynomials from Hermitian Matrices

abstract:
  A unified theory of orthogonal polynomials of a discrete variable is
presented through the eigenvalue problem of hermitian matrices of finite or
infinite dimensions. It can be considered as a matrix version of exactly
solvable Schr\"odinger equations. The hermitian matrices (factorisable
Hamiltonians) are real symmetric tri-diagonal (Jacobi) matrices corresponding
to second order difference equations. By solving the eigenvalue problem in two
different ways, the duality relation of the eigenpolynomials and their dual
polynomials is explicitly established. Through the techniques of exact
Heisenberg operator solution and shape invariance, various quantities, the two
types of eigenvalues (the eigenvalues and the sinusoidal coordinates), the
coefficients of the three term recurrence, the normalisation measures and the
normalisation constants etc. are determined explicitly.


title:
Constraints on the Mass Accretion Rate of Neutrino-Cooled Disks in
  Gamma-Ray Bursts

abstract:
  We present a unified description of all the three known classes of optically
thick accretion disks around black holes, namely Shakura-Sunyaev disks, slim
disks, and neutrino-dominated accretion flows (NDAFs). It is found that NDAFs
have both a maximal and a minimal possible mass accretion rate at their each
radius. This may be suggestive of an interpretation for the origin of X-ray
flares observed in gamma-ray bursts.


title: Spin Entanglement of Two delocalised Fermions and Berry Phase

abstract:
  We have studied the entanglement of identical fermions in two spatial regions
in terms of the Berry phase acquired by their spins. The analysis is done from
the viewpoint of the geometrical interpretation of entanglement, where a
fermion is visualized as a scalar particle attached with a magnetic flux
quantum. The quantification of spin entanglement in terms of their Berry phases
is novel and generalises the relationship between the entanglement of
distinguishable spins and that of delocalised fermions.


title:
Cofiniteness conditions, projective covers and the logarithmic tensor
  product theory

abstract:
  We construct projective covers of irreducible V-modules in the category of
grading-restricted generalized V-modules when V is a vertex operator algebra
satisfying the following conditions: 1. V is C_{1}-cofinite in the sense of Li.
2. There exists a positive integer N such that the differences between the real
parts of the lowest conformal weights of irreducible V-modules are bounded by N
and such that the associative algebra A_{N}(V) is finite dimensional. This
result shows that the category of grading-restricted generalized V-modules is a
finite abelian category over C. Using the existence of projective covers, we
prove that if such a vertex operator algebra V satisfies in addition Condition
3, that irreducible V-modules are R-graded and C_{1}-cofinite in the sense of
the author, then the category of grading-restricted generalized V-modules is
closed under P(z)-tensor product operations for z in C^{\times}. We also prove
that other conditions for applying the logarithmic tensor product theory
developed by Lepowsky, Zhang and the author hold. Consequently, for such V,
this category has a natural structure of braided tensor category. In
particular, when $V$ is of positive energy and C_{2}-cofinite, Conditions 1--3
are satisfied and thus all the conclusions hold.


title:
Signed-eliminable graphs and free multiplicities on the braid
  arrangement

abstract:
  We define specific multiplicities on the braid arrangement by using
edge-bicolored graphs. To consider their freeness, we introduce the notion of
bicolor-eliminable graphs as a generalization of Stanley's classification
theory of free graphic arrangements by chordal graphs. This generalization
gives us a complete classification of the free multiplicities defined above. As
an application, we prove one direction of a conjecture of Athanasiadis on the
characterization of the freeness of the deformation of the braid arrangement in
terms of directed graphs.


title:
An Extension for Direct Gauge Mediation of Metastable Supersymmetry
  Breaking

abstract:
  We study the direct mediation of metastable supersymmetry breaking by a
\Phi^2-deformation to the ISS model and extend it by splitting both Tr\Phi and
Tr\Phi^2 terms in the superpotential and gauging the flavor symmetry. We find
that with such an extension the enough long-lived metastable vacua can be
obtained and the proper gaugino masses can be generated. Also, this allows for
constructing a kind of models which can avoid the Landau pole problem.
Especially, in our metastable vacua there exist a large region for the
parameter m_3 which can satisfy the phenomenology requirements and allow for a
low SUSY breaking scale (\sim 100 TeV).


title: Holography of Non-relativistic String on AdS5xS5

abstract:
  We discuss a holographic dual of a non-relativistic (NR) string on AdS5xS5.
The NR string can be regarded as a semiclassical string around an AdS2
classical solution corresponding to a straight Wilson line in the gauge-theory
side. The quadratic action with respect to the fluctuations is composed of free
massive and massless scalars, and free massive fermions on the AdS2
world-sheet. We show that the complete agreement of the spectra between the NR
string and a conformal quantum mechanics (CQM). Then we show a holographic
relation between normalizable modes of the NR string and wave functions in the
CQM. Then it may be argued from this result that an AdS2/CFT1 would be realized
in AdS5/CFT4. We can really discuss a GKPW-type relation by considering
non-normalizable modes of the NR string in Euclidean signature. Those modes
give a source term insertion to the Wilson line, which can also be regarded as
a small deformation of it.


title: Positive mass theorems for asymptotically de Sitter spacetimes

abstract:
  We use planar coordinates as well as hyperbolic coordinates to separate the
de Sitter spacetime into two parts. These two ways of cutting the de Sitter
give rise to two different spatial infinities. For spacetimes which are
asymptotic to either half of the de Sitter spacetime, we are able to provide
definitions of the total energy, the total linear momentum, the total angular
momentum, respectively. And we prove two positive mass theorems, corresponding
to these two sorts of spatial infinities, for spacelike hypersurfaces whose
mean curvatures are bounded by certain constant from above.

categories: math.DG gr-qc hep-ph hep-th math-ph math.MP


title:
Studies of Exclusive e+e- -> hadrons Reactions with Baryons and Strange
  Particles Using Initial State Radiation at Babar

abstract:
  New Babar results on exclusive e+e- -> hadrons reactions at low c.m. energy
with a baryon-antibaryon or K\bar{K} pair in the final state are presented.
Cross sections are measured using the initial state radiation technique from
the threshold up to 4--5 GeV. From the measured e+e- -> proton\antiproton,
Lambda\Lbar, Sigma0\Sigbar0, Lambda\Sigbar0(Sigma0\Lbar) cross sections we
derive effective baryon form factors and compare them with predictions. We
measure the K\bar{K}\pi(\eta), K+K-\pi\pi, K+K-3\pi, K+K-4\pi, K+K-K+K- final
states and also study their internal structure. A new Y(2175) state is observed
in e+e- -> K+K-f0(980), with f0\to\pi\pi. The total measured e+e- annihilation
cross section into final states including strange baryons or strange mesons is
estimated to be 10% of the full hadronic cross section.


title: A Class of Quantum LDPC Codes Constructed From Finite Geometries

abstract:
  Low-density parity check (LDPC) codes are a significant class of classical
codes with many applications. Several good LDPC codes have been constructed
using random, algebraic, and finite geometries approaches, with containing
cycles of length at least six in their Tanner graphs. However, it is impossible
to design a self-orthogonal parity check matrix of an LDPC code without
introducing cycles of length four.
  In this paper, a new class of quantum LDPC codes based on lines and points of
finite geometries is constructed. The parity check matrices of these codes are
adapted to be self-orthogonal with containing only one cycle of length four.
Also, the column and row weights, and bounds on the minimum distance of these
codes are given. As a consequence, the encoding and decoding algorithms of
these codes as well as their performance over various quantum depolarizing
channels will be investigated.


title: Non-Relativistic Gravitation: From Newton to Einstein and Back

abstract:
  We present an improvement to the Classical Effective Theory approach to the
non-relativistic or Post-Newtonian approximation of General Relativity. The
"potential metric field" is decomposed through a temporal Kaluza-Klein ansatz
into three NRG-fields: a scalar identified with the Newtonian potential, a
3-vector corresponding to the gravito-magnetic vector potential and a 3-tensor.
The derivation of the Einstein-Infeld-Hoffmann Lagrangian simplifies such that
each term corresponds to a single Feynman diagram providing a clear physical
interpretation. Spin interactions are dominated by the exchange of the
gravito-magnetic field. Leading correction diagrams corresponding to the 3PN
correction to the spin-spin interaction and the 2.5PN correction to the
spin-orbit interaction are presented.


title: Image of Schwartz Space Under Spectral Projection

abstract:
  Let $X= G/K$ symmetric space of non compact type, where $G$ is a rank-one
connected semisimple Lie group with finite center. We shall look at the
transform $ P_\lambda f(x) = f \ast \varphi_\lambda(x)$, where, $\lambda \in
\mathbb C$ and $\varphi_\lambda$ is the elementary spherical function. We shall
try to characterizes the image of the Schwartz spaces $S^p(X) $ where $0 < p
\leq 2$ under the above transform.


title:
A Characterization of Signed Graphs with Generalized Perfect Elimination
  Orderings

abstract:
  An important property of chordal graphs is that these graphs are
characterized by existence of perfect elimination orderings on their vertex
sets. In this paper, we generalize the notion of perfect elimination orderings
to signed graphs, and give a characterization for graphs admitting such
orderings, together with characterizations restricted to some subclasses and
further properties of those graphs.


title:
Spontaneous Lorentz and Diffeomorphism Violation, Massive Modes, and
  Gravity

abstract:
  Theories with spontaneous local Lorentz and diffeomorphism violation contain
massless Nambu-Goldstone modes, which arise as field excitations in the minimum
of the symmetry-breaking potential. If the shape of the potential also allows
excitations above the minimum, then an alternative gravitational Higgs
mechanism can occur in which massive modes involving the metric appear. The
origin and basic properties of the massive modes are addressed in the general
context involving an arbitrary tensor vacuum value. Special attention is given
to the case of bumblebee models, which are gravitationally coupled vector
theories with spontaneous local Lorentz and diffeomorphism violation. Mode
expansions are presented in both local and spacetime frames, revealing the
Nambu-Goldstone and massive modes via decomposition of the metric and bumblebee
fields, and the associated symmetry properties and gauge fixing are discussed.
The class of bumblebee models with kinetic terms of the Maxwell form is used as
a focus for more detailed study. The nature of the associated conservation laws
and the interpretation as a candidate alternative to Einstein-Maxwell theory
are investigated. Explicit examples involving smooth and Lagrange-multiplier
potentials are studied to illustrate features of the massive modes, including
their origin, nature, dispersion laws, and effects on gravitational
interactions. In the weak static limit, the massive mode and
Lagrange-multiplier fields are found to modify the Newton and Coulomb
potentials. The nature and implications of these modifications are examined.


title: Radiation from an accelerated quark via AdS/CFT

abstract:
  In this paper we investigate radiation by an accelerated quark in a strongly
coupled gauge theory via AdS/CFT correspondence. According to AdS/CFT
dictionary, we can read off energy density or energy flux of the radiation from
asymptotic gravitational field in AdS bulk sourced by an accelerated string
trailing behind the quark. In the case of an oscillating quark with frequency
$\Omega$, we show that the time averaged energy density is asymptotically
isotropic and it falls off as $(g_{\text{YM}}^2 N)^{1/2} \Omega^4/R^{2}$ with
distance $R$ from the source. In a toy model of a scattered quark by an
external field, we simply estimate Poynting vector by the bremsstrahlung
radiation and show that the energy flux is anisotropic outgoing radiation.
Based on these investigations, we discuss the properties of strongly coupled
gauge theory radiation in comparison with electromagnetic radiation.


title: Unbound excited states in 19,17C

abstract:
  The neutron-rich carbon isotopes 19,17C have been investigated via proton
inelastic scattering on a liquid hydrogen target at 70 MeV/nucleon. The
invariant mass method in inverse kinematics was employed to reconstruct the
energy spectrum, in which fast neutrons and charged fragments were detected in
coincidence using a neutron hodoscope and a dipole magnet system. A peak has
been observed with an excitation energy of 1.46(10) MeV in 19C, while three
peaks with energies of 2.20(3), 3.05(3), and 6.13(9) MeV have been observed in
17C. Deduced cross sections are compared with microscopic DWBA calculations
based on p-sd shell model wave functions and modern nucleon-nucleus optical
potentials. Jpi assignments are made for the four observed states as well as
the ground states of both nuclei.


title: Phase-Space Noncommutative Quantum Cosmology

abstract:
  We present a noncommutative extension of Quantum Cosmology and study the
Kantowski-Sachs (KS) cosmological model requiring that the two scale factors of
the KS metric, the coordinates of the system, and their conjugate canonical
momenta do not commute. Through the ADM formalism, we obtain the Wheeler-DeWitt
(WDW) equation for the noncommutative system. The Seiberg-Witten map is used to
transform the noncommutative equation into a commutative one, i.e. into an
equation with commutative variables, which depend on the noncommutative
parameters, $\theta$ and $\eta$. Numerical solutions are found both for the
classical and the quantum formulations of the system. These solutions are used
to characterize the dynamics and the state of the universe. From the classical
solutions we obtain the behavior of quantities such as the volume expansion,
the shear and the characteristic volume. However the analysis of these
quantities does not lead to any restriction on the value of the noncommutative
parameters, $\theta$ and $\eta$. On the other hand, for the quantum system, one
can obtain, via the numerical solution of the WDW equation, the wave function
of the universe both for commutative as well as for the noncommutative models.
Interestingly, we find that the existence of suitable solutions of the WDW
equation imposes bounds on the values of the noncommutative parameters.
Moreover, the noncommutativity in the momenta leads to damping of the wave
function implying that this noncommutativity can be of relevance for the
selection of possible initial states of the early universe.


title: Long-Run Accuracy of Variational Integrators in the Stochastic Context

abstract:
  This paper presents a Lie-Trotter splitting for inertial Langevin equations
(Geometric Langevin Algorithm) and analyzes its long-time statistical
properties. The splitting is defined as a composition of a variational
integrator with an Ornstein-Uhlenbeck flow. Assuming the exact solution and the
splitting are geometrically ergodic, the paper proves the discrete invariant
measure of the splitting approximates the invariant measure of inertial
Langevin to within the accuracy of the variational integrator in representing
the Hamiltonian. In particular, if the variational integrator admits no energy
error, then the method samples the invariant measure of inertial Langevin
without error. Numerical validation is provided using explicit variational
integrators with first, second, and fourth order accuracy.


title: Introduction to the Galois Theory of Linear Differential Equations

abstract:
  This is an expanded version of the 10 lectures given as the 2006 London
Mathematical Society Invited Lecture Series at the Heriot-Watt University 31
July - 4 August 2006.


title:
Single- and Double-Pion Production in Nucleon Collisions on the Nucleon
  and on Nuclei -- the ABC Effect and its Possible Origin in a Dibaryonic
  Resonance

abstract:
  The ABC effect -- an intriguing low-mass enhancement in the $\pi\pi$
invariant mass spectrum -- is known from inclusive measurements of two-pion
production in nuclear fusion reactions. First exclusive measurements carried
out at CELSIUS-WASA for the fusion reactions leading to d or $^3$He reveal this
effect to be a $\sigma$ channel phenomenon associated with the formation of a
$\Delta\Delta$ system in the intermediate state and combined with a
resonance-like behavior in the total cross section. Together with the
observation that the differential distributions do not change in shape over the
resonance region the features fulfill the criteria of an isoscalar s-channel
resonance in $pn$ and $NN\pi\pi$ systems, if the two emitted nucleons are
bound. It obviously is robust enough to survive in nuclei as a dibaryonic
resonance configuration. In this context also the phenomenon of $N\Delta$
resonances is reexamined.


title: TRUST-TECH based Methods for Optimization and Learning

abstract:
  Many problems that arise in machine learning domain deal with nonlinearity
and quite often demand users to obtain global optimal solutions rather than
local optimal ones. Optimization problems are inherent in machine learning
algorithms and hence many methods in machine learning were inherited from the
optimization literature. Popularly known as the initialization problem, the
ideal set of parameters required will significantly depend on the given
initialization values. The recently developed TRUST-TECH (TRansformation Under
STability-reTaining Equilibria CHaracterization) methodology systematically
explores the subspace of the parameters to obtain a complete set of local
optimal solutions. In this thesis work, we propose TRUST-TECH based methods for
solving several optimization and machine learning problems. Two stages namely,
the local stage and the neighborhood-search stage, are repeated alternatively
in the solution space to achieve improvements in the quality of the solutions.
Our methods were tested on both synthetic and real datasets and the advantages
of using this novel framework are clearly manifested. This framework not only
reduces the sensitivity to initialization, but also allows the flexibility for
the practitioners to use various global and local methods that work well for a
particular problem of interest. Other hierarchical stochastic algorithms like
evolutionary algorithms and smoothing algorithms are also studied and
frameworks for combining these methods with TRUST-TECH have been proposed and
evaluated on several test systems.


title:
On irreducible algebras of conformal endomorphisms over a linear
  algebraic group

abstract:
  We study the algebra of conformal endomorphisms $\Cend^{G,G}_n$ of a finitely
generated free module $M_n$ over the coordinate Hopf algebra $H$ of a linear
algebraic group $G$. It is shown that a conformal subalgebra of $\Cend_n$
acting irreducibly on $M_n$ generates an essential left ideal of
$\Cend^{G,G}_n$ if enriched with operators of multiplication on elements of
$H$. In particular, we describe such subalgebras for the case when $G$ is
finite.


title: Observation of all-optical bump-on-tail instability

abstract:
  We demonstrate an all-optical bump-on-tail instability by considering the
nonlinear interaction of two partially-coherent spatial beams. For weak wave
coupling, we observe momentum transfer with no variation in intensity. For
strong wave coupling, modulations appear in intensity and evidence appears for
wave (Langmuir) collapse at large scales. Borrowing plasma language, these
limits represent regimes of weak and strong spatial optical turbulence. In both
limits, the internal spectral energy redistribution is observed by recording
and reconstructing a hologram of the evolving dynamics. The results are
universal and can appear in any wave-kinetic system with short-wave/long-wave
coupling.


title: Detectors and flux instrumentation for future neutrino facilities

abstract:
  This report summarises the conclusions from the detector group of the
International Scoping Study of a future Neutrino Factory and Super-Beam
neutrino facility. The baseline detector options for each possible neutrino
beam are defined as follows:
  1. A very massive (Megaton) water Cherenkov detector is the baseline option
for a sub-GeV Beta Beam and Super Beam facility.
  2. There are a number of possibilities for either a Beta Beam or Super Beam
(SB) medium energy facility between 1-5 GeV. These include a totally active
scintillating detector (TASD), a liquid argon TPC or a water Cherenkov
detector.
  3. A 100 kton magnetized iron neutrino detector (MIND) is the baseline to
detect the wrong sign muon final states (golden channel) at a high energy
(20-50 GeV) neutrino factory from muon decay. A 10 kton hybrid neutrino
magnetic emulsion cloud chamber detector for wrong sign tau detection (silver
channel) is a possible complement to MIND, if one needs to resolve degeneracies
that appear in the $\delta$-$\theta_{13}$ parameter space.


title:
Half-Metallicity in Undoped and Boron Doped Graphene Nanoribbons in
  Presence of Semi-local Exchange-Correlation Interactions

abstract:
  We perform density functional calculations on one-dimensional zigzag edge
graphene nano-ribbons (ZGNRs) of different widths, with and without edge doping
including semi-local exchange-correlations. Our study reveals that, although
the ground state of edge passivated (with hydrogen) ZGNRs prefers to be
anti-ferromagnetic, the doping of both the edges with Boron atoms stabilizes
the system in a ferromagnetic ground state. Both the local and semi-local
exchange-correlations result in half-metallicity in edge passivated ZGNRs at a
finite cross-ribbon electric field. However, the ZGNR with Boron edges shows
half-metallic behavior irrespective of the ribbon-width even in absence of
electric field and this property sustains for any field strength, opening a
huge possibility of applications in spintronics.


title: On cluster algebras arising from unpunctured surfaces

abstract:
  We study cluster algebras that are associated to unpunctured surfaces with
coefficients arising from boundary arcs. We give a direct formula for the
Laurent polynomial expansion of cluster variables in these cluster algebras in
terms of certain paths on a triangulation of the surface. As an immediate
consequence, we prove the positivity conjecture of Fomin and Zelevinsky for
these cluster algebras. In the special case where the cluster algebra is
acyclic, we also give a formula for the expansion of cluster variables as a
polynomial whose indeterminates are the cluster variables contained in the
union of an arbitrary acyclic cluster and all its neighbouring clusters in the
mutation graph.


title: Conformal Invariance in the Leigh-Strassler deformed N=4 SYM Theory

abstract:
  We consider a full Leigh-Strassler deformation of the ${\cal N}=4$ SYM theory
and look for conditions under which the theory would be conformally invariant
and finite. Applying the algorithm of perturbative adjustments of the couplings
we construct a family of theories which are conformal up to 3 loops in the
non-planar case and up to 4 loops in the planar one. We found particular
solutions in the planar case when the conformal condition seems to be exhausted
in the one loop order. Some of them happen to be unitary equivalent to the real
beta-deformed ${\cal N}=4$ SYM theory, while others are genuine. We present the
arguments that these solutions might be valid in any loop order.


title:
Orthogonal involution on algebras of degree 16 and the Killing form of
  E8

abstract:
  We exploit various inclusions of algebraic groups to give a new construction
of groups of type E8, determine the Killing forms of the resulting E8's, and
define an invariant of central simple algebras of degree 16 with orthogonal
involution "in I^3", equivalently, groups of type D8 with a half-spin
representation defined over the base field. The determination of the Killing
form is done by restricting the adjoint representation to various twisted forms
of PGL2 and requires very little computation.
  An appendix by Kirill Zainoulline contains a type of "index reduction" result
for groups of type D.


title: Theory and Phenomenology of Dirac Leptogenesis

abstract:
  Dirac leptogenesis, in which neutrinos are purely Dirac and develop small but
nonzero effective masses without the aid of the see-saw mechanism, provides an
interesting alternative to the standard leptogenesis picture. Here we review
the theory and phenomenology of Dirac leptogenesis and show that it is a viable
theory capable of simultaneously satisfying all relevant bounds from cosmology,
neutrino physics, and flavor violation. In addition, we also explore several
potential extensions of the model, such as the possibility of right-handed
sneutrino dark matter and the potential for relating the leptogenesis mechanism
to the origin of the mu-term. Theories with a heavy gravitino and gaugino
masses generated by anomaly mediation emerge as one natural context for Dirac
leptogenesis. In such models the lightest neutralino is often expected to be
predominately wino or Higgsino, and is a viable dark matter candidate. We
conclude with an examination of the prospects for detecting the effectively
monoenergetic photon signal that results from the annihilation of such a dark
matter particle in the galactic halo.


title:
On the Throughput of Secure Hybrid-ARQ Protocols for Gaussian
  Block-Fading Channels

abstract:
  The focus of this paper is an information-theoretic study of retransmission
protocols for reliable packet communication under a secrecy constraint. The
hybrid automatic retransmission request (HARQ) protocol is revisited for a
block-fading wire-tap channel, in which two legitimate users communicate over a
block-fading channel in the presence of a passive eavesdropper who intercepts
the transmissions through an independent block-fading channel. In this model,
the transmitter obtains a 1-bit ACK/NACK feedback from the legitimate receiver
via an error-free public channel. Both reliability and confidentiality of
secure HARQ protocols are studied by the joint consideration of channel coding,
secrecy coding, and retransmission protocols. In particular, the error and
secrecy performance of repetition time diversity (RTD) and incremental
redundancy (INR) protocols are investigated based on good Wyner code sequences,
which ensure that the confidential message is decoded successfully by the
legitimate receiver and is kept in total ignorance by the eavesdropper for a
given set of channel realizations. This paper first illustrates that there
exists a good rate-compatible Wyner code family which ensures a secure INR
protocol. Next, two types of outage probabilities, connection outage and
secrecy outage probabilities are defined in order to characterize the tradeoff
between the reliability of the legitimate communication link and the
confidentiality with respect to the eavesdropper's link. For a given
connection/secrecy outage probability pair, an achievable throughput of secure
HARQ protocols is derived for block-fading channels. Finally, both asymptotic
analysis and numerical computations demonstrate the benefits of HARQ protocols
to throughput and secrecy.


title:
Fast projectile stopping power of quantal multi-component strongly
  coupled plasmas

abstract:
  The Bethe-Larkin formula for the fast projectile stopping power is extended
to multi-component plasmas. The results are to contribute to the correct
interpretation of the experimental data, which could permit to test the
existing and future models of thermodynamic, static, and dynamic
characteristics of strongly coupled Coulomb systems.


title:
Uniqueness for the martingale problem associated with pure jump
  processes of variable order

abstract:
  Let $L$ be the operator defined on $C^2$ functions by $$L
f(x)=\int[f(x+h)-f(x)-1_{(|h|\leq 1)}\nabla f(x)\cdot
h]\frac{n(x,h)}{|h|^{d+\alpha(x)}}dh.$$ This is an operator of variable order
and the corresponding process is of pure jump type. We consider the martingale
problem associated with $L$. Sufficient conditions for existence and uniqueness
are given. Transition density estimates for $\alpha$-stable processes are also
obtained.


title: The hexagon Wilson loop and the BDS ansatz for the six-gluon amplitude

abstract:
  As a test of the gluon scattering amplitude/Wilson loop duality, we evaluate
the hexagonal light-like Wilson loop at two loops in N=4 super Yang-Mills
theory. We compare its finite part to the Bern-Dixon-Smirnov (BDS) conjecture
for the finite part of the six-gluon amplitude. We find that the two
expressions have the same behavior in the collinear limit, but they differ by a
non-trivial function of the three (dual) conformally invariant variables. This
implies that either the BDS conjecture or the gluon amplitude/Wilson loop
duality fails for the six-gluon amplitude, starting from two loops. Our results
are in qualitative agreement with the analysis of Alday and Maldacena of
scattering amplitudes with infinitely many external gluons.


title: Surfaces in three-dimensional Lie groups in terms of spinors

abstract:
  This is a survey of results on surfaces in noncommutative three-dimensional
Lie groups obtained by using the Weierstrass (spinor) representation of
surfaces. It is based on the talk given at the conference "Geometry related to
the theory of integrable systems" (RIMS, Kyoto, September 2007).


title: Bayesian Image Reconstruction Based on Voronoi Diagrams

abstract:
  We present a Bayesian Voronoi image reconstruction technique (VIR) for
interferometric data. Bayesian analysis applied to the inverse problem allows
us to derive the a-posteriori probability of a novel parameterization of
interferometric images. We use a variable Voronoi diagram as our model in place
of the usual fixed pixel grid. A quantization of the intensity field allows us
to calculate the likelihood function and a-priori probabilities. The Voronoi
image is optimized including the number of polygons as free parameters. We
apply our algorithm to deconvolve simulated interferometric data. Residuals,
restored images and chi^2 values are used to compare our reconstructions with
fixed grid models. VIR has the advantage of modeling the image with few
parameters, obtaining a better image from a Bayesian point of view.


title:
Black hole collapse simulated by vacuum fluctuations with a moving
  semi-transparent mirror

abstract:
  Creation of scalar massless particles in two-dimensional Minkowski
space-time--as predicted by the dynamical Casimir effect--is studied for the
case of a semitransparent mirror initially at rest, then accelerating for some
finite time, along a trajectory that simulates a black hole collapse (defined
by Walker, and Carlitz and Willey), and finally moving with constant velocity.
When the reflection and transmission coefficients are those in the model
proposed by Barton, Calogeracos, and Nicolaevici [$r(w)=-i\alpha/(\w+i\alpha)$
and $s(w)=\w/(\w+i\alpha)$, with $\alpha\geq 0$], the Bogoliubov coefficients
on the back side of the mirror can be computed exactly. This allows us to prove
that, when $\alpha$ is very large (case of an ideal, perfectly reflecting
mirror) a thermal emission of scalar massless particles obeying Bose-Einstein
statistics is radiated from the mirror (a black body radiation), in accordance
with results previously obtained in the literature. However, when $\alpha$ is
finite (semitransparent mirror, a physically realistic situation) the striking
result is obtained that the thermal emission of scalar massless particles obeys
Fermi-Dirac statistics. We also show here that the reverse change of statistics
takes place in a bidimensional fermionic model for massless particles, namely
that the Fermi-Dirac statistics for the completely reflecting situation will
turn into the Bose-Einstein statistics for a partially reflecting, physical
mirror.


title: Analogues of the Jordan-Holder theorem for transitive G-sets

abstract:
  Let G be a transitive group of permutations of a finite set X, and suppose
that some element of G has at most two orbits on X. We prove that any two
maximal chains of groups between G and a point-stabilizer of G have the same
length, and the same sequence of relative indices between consecutive groups
(up to permutation). We also deduce the same conclusion when G has a transitive
quasi-Hamiltonian subgroup.


title: Cosmological Plebanski theory

abstract:
  We consider the cosmological symmetry reduction of the Plebanski action as a
toy-model to explore, in this simple framework, some issues related to loop
quantum gravity and spin-foam models. We make the classical analysis of the
model and perform both path integral and canonical quantizations. As for the
full theory, the reduced model admits two types of classical solutions:
topological and gravitational ones. The quantization mixes these two solutions,
which prevents the model to be equivalent to standard quantum cosmology.
Furthermore, the topological solution dominates at the classical limit. We also
study the effect of an Immirzi parameter in the model.


title: Reflecting Magnon Bound States

abstract:
  In N=4 super Yang-Mills spin chain, we compute reflection amplitudes of
magnon bound-state off giant graviton. We first compute the reflection
amplitude off Y=0 brane boundary and compare it with the scattering amplitude
between two magnon bound-states in the bulk. We find that analytic structure of
the two amplitudes are intimately related each other: the boundary reflection
amplitude is a square-root of the bulk scattering amplitude. Using such
relation as a guide and taking known results at weak and strong coupling limits
as inputs, we find the reflection amplitude of an elementary magnon off Z=0
giant graviton boundary. The reflection phase factor is shown to solve crossing
and unitarity relations. We then compute the reflection amplitude of magnon
bound-state off the Z=0 brane boundary and observe that its analytic structures
are again intimately related to the bulk scattering and the Y=0 boundary
reflection amplitudes. We also take dyonic giant magnon limit of these
reflection amplitudes and confirm that their phase-shifts agree completely with
string worldsheet computations based on complex sine-Gordon soliton scattering.


title:
The Host Galaxy and The Extended Emission-Line Region of The Radio
  Galaxy 3C 79

abstract:
  We present extensive ground-based spectroscopy and HST imaging of 3C79, an FR
II radio galaxy associated with a luminous extended emission-line region
(EELR). Surface brightness modeling of an emission-line-free HST R-band image
reveals that the host galaxy is a massive elliptical with a compact companion
0.8" away and 4 magnitudes fainter. The host galaxy spectrum is best described
by an intermediate-age (1.3 Gyr) stellar population (4% by mass), superimposed
on a 10 Gyr old population and a power law (\alpha_{\lambda} = -1.8); the
stellar populations are consistent with super-solar metallicities, with the
best fit given by the 2.5 Z_sun models. We derive a dynamical mass of 4E11
M_sun within the effective radius from the velocity dispersion. The EELR
spectra clearly indicate that the EELR is photoionized by the hidden central
engine. Photoionization modeling shows evidence that the gas metallicity in
both the EELR and the nuclear narrow-line region is mildly sub-solar (0.3 - 0.7
Z_sun) -- significantly lower than the super-solar metallicities deduced from
typical active galactic nuclei in the SDSS. The more luminous filaments in the
EELR exhibit a velocity field consistent with a common disk rotation. Fainter
clouds, however, show high approaching velocities that are uncoupled with this
apparent disk rotation. The striking similarities between this EELR and the
EELRs around steep-spectrum radio-loud quasars provide further evidence for the
orientation-dependent unification schemes. The metal-poor gas is almost
certainly not native to the massive host galaxy. We suggest that the close
companion galaxy could be the tidally stripped bulge of a late-type galaxy that
is merging with the host galaxy. The interstellar medium of such a galaxy is
probably the source for the low-metallicity gas in 3C79.


title: Mixed Sneutrinos, Dark Matter and the LHC

abstract:
  We study the phenomenology of supersymmetric models in which gauge-singlet
scalars mix with the MSSM sneutrinos through weak-scale $A$ terms. After
reviewing the constraints on mixed-sneutrino dark matter from measurements of
$\Omega_{CDM}$ and from direct-detection experiments, we explore
mixed-sneutrino signatures relevant to the LHC. For a mixed-sneutrino LSP and a
right-handed slepton NLSP, decays of the lightest neturalino can produce
opposite-sign, same-flavor (OSSF) dileptons with an invariant-mass distribution
shifted away from the kinematic endpoint. In different parameter regions, the
charginos and neutralinos produced in cascades all decay dominantly to the
lighter sneutrinos, leading to a kinematic edge in the jet-lepton
invariant-mass distribution from the decay chain $\tilde{q} \to \chi^- q \to
\snu^* l q$, without an OSSF dilepton signature. We explore the possibility of
using mass estimation methods to distinguish this mixed-sneutrino jet-lepton
signature from an MSSM one. Finally, we consider signatures associated with
Higgs-lepton or $Z$-lepton production in cascades involving the heavier
sneutrinos.


title: Non-unimodular reductions and N = 4 gauged supergravities

abstract:
  We analyze the class of four-dimensional N = 4 supergravities obtained by
gauging the axionic shift and axionic rescaling symmetries. These theories are
formulated with the machinery of embedding tensors and shown to be deducible
from higher dimensions using a Scherk--Schwarz reduction with a twist by a
non-compact symmetry. This allows to evade the usual unimodularity requirement
and completes the dictionary between heterotic gaugings and fluxes, at least
for the "geometric sector".


title:
Lower bounds for the greatest possible number of colors in interval edge
  colorings of bipartite cylinders and bipartite tori

abstract:
  An interval edge t-coloring of a graph G is a proper edge coloring of G with
colors 1,2...,t such that at least one edge of G is colored by color
i,i=1,2...,t, and the edges incident with each vertex v are colored by d_{G}(v)
consecutive colors, where d_{G}(v) is the degree of the vertex v in G. In this
paper interval edge colorings of bipartite cylinders and bipartite tori are
investigated.


title:
UV/Optical Detections of Candidate Tidal Disruption Events by GALEX and
  CFHTLS

abstract:
  We present two luminous UV/optical flares from the nuclei of apparently
inactive early-type galaxies at z=0.37 and 0.33 that have the radiative
properties of a flare from the tidal disruption of a star. In this paper we
report the second candidate tidal disruption event discovery in the UV by the
GALEX Deep Imaging Survey, and present simultaneous optical light curves from
the CFHTLS Deep Imaging Survey for both UV flares. The first few months of the
UV/optical light curves are well fitted with the canonical t^(-5/3) power-law
decay predicted for emission from the fallback of debris from a tidally
disrupted star. Chandra ACIS X-ray observations during the flares detect soft
X-ray sources with T_bb= (2-5) x 10^5 K or Gamma > 3 and place limits on hard
X-ray emission from an underlying AGN down to L_X (2-10 keV) <~ 10^41 ergs/s.
Blackbody fits to the UV/optical spectral energy distributions of the flares
indicate peak flare luminosities of > 10^44-10^45 ergs/s. The temperature,
luminosity, and light curves of both flares are in excellent agreement with
emission from a tidally disrupted main sequence star onto a central black hole
of several times 10^7 msun. The observed detection rate of our search over ~
2.9 deg^2 of GALEX Deep Imaging Survey data spanning from 2003 to 2007 is
consistent with tidal disruption rates calculated from dynamical models, and we
use these models to make predictions for the detection rates of the next
generation of optical synoptic surveys.


title: The Halpha-based Star Formation Rate Density of the Universe at z=0.84

abstract:
  We present the results of an Halpha near-infrared narrow-band survey
searching for star-forming galaxies at redshift z=0.84. This work is an
extension of our previous narrow-band studies in the optical at lower
redshifts. After removal of stars and redshift interlopers (using spectroscopic
and photometric redshifts), we build a complete sample of 165 Halpha emitters
in the Extended Groth strip and GOODS-N fields with L(Halpha)>10^41 erg/s. We
compute the Halpha luminosity function at z=0.84 after corrections for [NII]
flux contamination, extinction, systematic errors, and incompleteness. Our
sources present an average dust extinction of A(Halpha)=1.5 mag. Adopting
Halpha as a surrogate for the instantaneous star formation rate (SFR), we
measure a extinction-corrected SFR density of 0.17+-0.03 M_sun/yr/Mpc3.
Combining this result to our prior measurements at z=0.02, 0.24, and 0.40, we
derive an Halpha-based evolution of the SFR density proportional to (1+z)^beta
with beta=3.8+-0.5. This evolution is consistent with that derived by other
authors using different SFR tracers.


title: Packing 3-Vertex Paths in 2-Connected Graphs

abstract:
  We give a construction that provides infinitely many 2-connected, cubic,
bipartite, and planar graphs G with 3k vertices and such that the number of
disjoint copies of a 3-vertex path in G is less than k.


title:
The CODEX-ESPRESSO experiment: cosmic dynamics, fundamental physics,
  planets and much more..

abstract:
  CODEX, a high resolution, super-stable spectrograph to be fed by the E-ELT,
the most powerful telescope ever conceived, will for the first time provide the
possibility of directly measuring the change of the expansion rate of the
Universe with time and much more, from the variability of fundamental constants
to the search for other earths. A study for the implementation at the VLT of a
precursor of CODEX, dubbed ESPRESSO, is presently carried out by a
collaboration including ESO, IAC, INAF, IoA Cambridge and Observatoire de
Geneve. The present talk is focused on the cosmological aspects of the
experiment.


title: Biology of Applied Digital Ecosystems

abstract:
  A primary motivation for our research in Digital Ecosystems is the desire to
exploit the self-organising properties of biological ecosystems. Ecosystems are
thought to be robust, scalable architectures that can automatically solve
complex, dynamic problems. However, the biological processes that contribute to
these properties have not been made explicit in Digital Ecosystems research.
Here, we discuss how biological properties contribute to the self-organising
features of biological ecosystems, including population dynamics, evolution, a
complex dynamic environment, and spatial distributions for generating local
interactions. The potential for exploiting these properties in artificial
systems is then considered. We suggest that several key features of biological
ecosystems have not been fully explored in existing digital ecosystems, and
discuss how mimicking these features may assist in developing robust, scalable
self-organising architectures. An example architecture, the Digital Ecosystem,
is considered in detail. The Digital Ecosystem is then measured experimentally
through simulations, with measures originating from theoretical ecology, to
confirm its likeness to a biological ecosystem. Including the responsiveness to
requests for applications from the user base, as a measure of the 'ecological
succession' (development).


title: Single Pion Measurement Capabilities at SciBooNE

abstract:
  The precise knowledge of the single pion production cross-section of neutrino
around the ~1 GeV energy region is an essential ingredient in the
interpretation of neutrino oscillation experiments. The unique opportunities
and prospects of single pion measurements at SciBooNE are described.


title: Hedgehog black holes and the Polyakov loop at strong coupling

abstract:
  In N=4 super-Yang-Mills theory at large N, large \lambda, and finite
temperature, the value of the Wilson-Maldacena loop wrapping the Euclidean time
circle (the Polyakov-Maldacena loop, or PML) is computed by the area of a
certain minimal surface in the dual supergravity background. This prescription
can be used to calculate the free energy as a function of the PML (averaged
over the spatial coordinates), by introducing into the bulk action a Lagrange
multiplier term that fixes the (average) area of the appropriate minimal
surface. This term, which can also be viewed as a chemical potential for the
PML, contributes to the bulk stress tensor like a string stretching from the
horizon to the boundary (smeared over the angular directions). We find the
corresponding "hedgehog" black hole solutions numerically, within an
SO(6)-preserving ansatz, and derive part of the free energy diagram for the
PML. As a warm-up problem, we also find exact solutions for hedgehog black
holes in pure gravity, and derive the free energy and phase diagrams for that
system.


title:
Simulations of the Temperature Dependence of the Charge Transfer
  Inefficiency in a High-Speed CCD

abstract:
  Results of detailed simulations of the charge transfer inefficiency of a
prototype serial readout CCD chip are reported. The effect of radiation damage
on the chip operating in a particle detector at high frequency at a future
accelerator is studied, specifically the creation of two electron trap levels,
0.17 eV and 0.44 eV below the bottom of the conduction band. Good agreement is
found between simulations using the ISE-TCAD DESSIS program and an analytical
model for the former level but not for the latter. Optimum operation is
predicted to be at about 250 K where the effects of the traps is minimal; this
being approximately independent of readout frequency in the range 7-50 MHz. The
work has been carried out within the Linear Collider Flavour Identification
(LCFI) collaboration in the context of the International Linear Collider (ILC)
project.


title: Hidden Symmetries of Higher-Dimensional Black Hole Spacetimes

abstract:
  The paper contains a brief review of recent results on hidden symmetries in
higher dimensional black hole spacetimes. We show how the existence of a
principal CKY tensor (that is a closed non-degenerate conformal Killing-Yano
2-form) allows one to generate a `tower' of Killing-Yano and Killing tensors
responcible for hidden symmetries. These symmetries imply complete
integrability of geodesic equations and the complete separation of variables in
the Hamilton-Jacobi, Klein-Gordon and Dirac equations in the general
Kerr-NUT-(A)dS metrics.


title:
Invariant measures on the space of horofunctions of a word hyperbolic
  group

abstract:
  We introduce a natural equivalence relation on the space $\sH_0$ of
horofunctions of a word hyperbolic group that take the value 0 at the identity.
We show that there are only finitely many ergodic measures that are invariant
under this relation. This can be viewed as a discrete analog of the
Bowen-Marcus theorem. Furthermore, if $\eta$ is such a measure and $G$ acts on
a space $(X,\mu)$ by p.m.p. transformations then $\eta \times \mu$ is virtually
ergodic with respect to a natural equivalence relation on $\sH_0\times X$. This
is comparable to a special case of the Howe-Moore theorem. These results are
applied to prove a new ergodic theorem for spherical averages in the case of a
word hyperbolic group acting on a finite space.


title:
Creating a Digital Ecosystem: Service-Oriented Architectures with
  Distributed Evolutionary Computing

abstract:
  We start with a discussion of the relevant literature, including Nature
Inspired Computing as a framework in which to understand this work, and the
process of biomimicry to be used in mimicking the necessary biological
processes to create Digital Ecosystems. We then consider the relevant
theoretical ecology in creating the digital counterpart of a biological
ecosystem, including the topological structure of ecosystems, and evolutionary
processes within distributed environments. This leads to a discussion of the
relevant fields from computer science for the creation of Digital Ecosystems,
including evolutionary computing, Multi-Agent Systems, and Service-Oriented
Architectures. We then define Ecosystem-Oriented Architectures for the creation
of Digital Ecosystems, imbibed with the properties of self-organisation and
scalability from biological ecosystems, including a novel form of distributed
evolutionary computing.


title: Quiver varieties and Beilinson-Drinfeld Grassmannians of type A

abstract:
  We construct Nakajima's quiver varieties of type A in terms of conjugacy
classes of matrices and (non-Slodowy's) transverse slices naturally arising
from affine Grassmannians. In full generality quiver varieties are embedded
into Beilinson-Drinfeld Grassmannians of type A. Our construction provides a
compactification of Nakajima's quiver varieties and a decomposition of an
affine Grassmannian into a disjoint union of quiver varieties. As an
application we provide a geometric version of skew and symmetric $(GL(m),
GL(n))$ duality.


title:
On the Empirical Importance of the Conditional Skewness Assumption in
  Modelling the Relationship Between Risk and Return

abstract:
  The main goal of this paper is an application of Bayesian inference in
testing the relation between risk and return on the financial instruments. On
the basis of the Intertemporal CAPM model we built a general sampling model
suitable in analysing such a relationship. The most important feature of our
assumptions is that the skewness of the conditional distribution of returns is
used as an alternative source of relation between risk and return. This general
specification relates to GARCH-In-Mean model. In order to make conditional
distribution of financial returns skewed we considered a constructive approach
based on the inverse probability integral transformation. In particular, we
apply the hidden truncation mechanism, two equivalent approaches of the inverse
scale factors, order statistics concept, Beta and Bernstein distribution
transformations, and also the constructive method. Based on the daily excess
returns on the Warsaw Stock Exchange Index we checked the empirical importance
of the conditional skewness assumption on the relation between risk and return
on the Warsaw Stock Market. We present posterior probabilities of all competing
specifications as well as the posterior analysis of positive sign of the tested
relationship.


title: Pi-Pi Scattering Lengths in the Light of Precision Measurements

abstract:
  I summarize the history of theoretical predictions of, and experimental
attempts to measure, pion-pion (S-wave) scattering lengths. Recent measurements
at CERN confirm Weinberg's 1966 prediction of the I=2 scattering length and
Basdevant and Lee's subsequent correction of the Weinberg I=0 value by
inclusion of an S-wave I=0 resonance.


title: The probability of entanglement

abstract:
  We show that states on tensor products of matrix algebras whose ranks are
relatively small are {\em almost surely} entangled, but that states of maximum
rank are not. More precisely, let $M=M_m(\mathbb C)$ and $N=M_n(\mathbb C)$ be
full matrix algebras with $m\geq n$, fix an arbitrary state $\omega$ of $N$,
and let $E(\omega)$ be the set of all states of $M\otimes N$ that extend
$\omega$. The space $E(\omega)$ contains states of rank $r$ for every
$r=1,2,...,m\cdot\rank\omega$, and it has a filtration into compact subspaces
$$ E^1(\omega)\subseteq E^2(\omega)\subseteq ...\subseteq
E^{m\cdot\rank\omega}=E(\omega), $$ where $E^r(\omega)$ is the set of all
states of $E(\omega)$ having rank $\leq r$.
  We show first that for every $r$, there is a real-analytic manifold $V^r$,
homogeneous under a transitive action of a compact group $G^r$, which
parameterizes $E^r(\omega)$. The unique $G^r$-invariant probability measure on
$V^r$ promotes to a probability measure $P^{r,\omega}$ on $E^r(\omega)$, and
$P^{r,\omega}$ assigns probability 1 to states of rank $r$. The resulting
probability space $(E^r(\omega),P^{r,\omega})$ represents ``choosing a rank $r$
extension of $\omega$ at random".
  Main result: For every $r=1,2,...,[\rank \omega/2]$, states of
$(E^r(\omega),P^{r,\omega})$ are almost surely entangled.


title: Search for the Decay $K^0_L \to \pi^0 \nu \bar{\nu}$

abstract:
  We performed a search for the $K^0_L \to \pi^0 \nu \bar{\nu}$ decay at the
KEK 12-GeV proton synchrotron. No candidate events were observed. An upper
limit on the branching ratio for the decay was set to be $6.7 \times 10^{-8}$
at the 90% confidence level.


title: T. Dauxois' "Non-Gaussian distributions under scrutiny" under scrutiny

abstract:
  A recent paper by T. Dauxois entitled "Non-Gaussian distributions under
scrutiny" is submitted to scrutiny. Several comments on its content are made,
which constitute, at the same time, a brief state-of-the-art review of
nonextensive statistical mechanics, a current generalization of the
Boltzmann-Gibbs theory. Some inadvertences and misleading sentences are pointed
out as well.


title:
Simulation of the matrix Bingham-von Mises-Fisher distribution, with
  applications to multivariate and relational data

abstract:
  Orthonormal matrices play an important role in reduced-rank matrix
approximations and the analysis of matrix-valued data. A matrix Bingham-von
Mises-Fisher distribution is a probability distribution on the set of
orthonormal matrices that includes linear and quadratic terms, and arises as a
posterior distribution in latent factor models for multivariate and relational
data. This article describes rejection and Gibbs sampling algorithms for
sampling from this family of distributions, and illustrates their use in the
analysis of a protein-protein interaction network.


title: Non-topological non-commutativity in string theory

abstract:
  Quantization of coordinates leads to the non-commutative product of
deformation quantization, but is also at the roots of string theory, for which
space-time coordinates become the dynamical fields of a two-dimensional
conformal quantum field theory. Appositely, open string diagrams provided the
inspiration for Kontsevich's solution of the long-standing problem of
quantization of Poisson geometry by virtue of his formality theorem. In the
context of D-brane physics non-commutativity is not limited, however, to the
topolocial sector. We show that non-commutative effective actions still make
sense when associativity is lost and establish a generalized
Connes-Flato-Sternheimer condition through second order in a derivative
expansion. The measure in general curved backgrounds is naturally provided by
the Born--Infeld action and reduces to the symplectic measure in the
topological limit, but remains non-singular even for degenerate Poisson
structures. Analogous superspace deformations by RR--fields are also discussed.


title:
A Framework for Providing E-Services to the Rural Areas using Wireless
  Ad Hoc and Sensor Networks

abstract:
  In recent years, the proliferation of mobile computing devices has driven a
revolutionary change in the computing world. The nature of ubiquitous devices
makes wireless networks the easiest solution for their interconnection. This
has led to the rapid growth of several wireless systems like wireless ad hoc
networks, wireless sensor networks etc. In this paper we have proposed a
framework for rural development by providing various e-services to the rural
areas with the help of wireless ad hoc and sensor networks. We have discussed
how timely and accurate information could be collected from the rural areas
using wireless technologies. In addition to this, we have also mentioned the
technical and operational challenges that could hinder the implementation of
such a framework in the rural areas in the developing countries.


title: Security in Wireless Sensor Networks: Issues and Challenges

abstract:
  Wireless Sensor Network (WSN) is an emerging technology that shows great
promise for various futuristic applications both for mass public and military.
The sensing technology combined with processing power and wireless
communication makes it lucrative for being exploited in abundance in future.
The inclusion of wireless communication technology also incurs various types of
security threats. The intent of this paper is to investigate the security
related issues and challenges in wireless sensor networks. We identify the
security threats, review proposed security mechanisms for wireless sensor
networks. We also discuss the holistic view of security for ensuring layered
and robust security in wireless sensor networks.


title:
Smartening the Environment using Wireless Sensor Networks in a
  Developing Country

abstract:
  The miniaturization process of various sensing devices has become a reality
by enormous research and advancements accomplished in Micro Electro-Mechanical
Systems (MEMS) and Very Large Scale Integration (VLSI) lithography. Regardless
of such extensive efforts in optimizing the hardware, algorithm, and protocols
for networking, there still remains a lot of scope to explore how these
innovations can all be tied together to design Wireless Sensor Networks (WSN)
for smartening the surrounding environment for some practical purposes. In this
paper we explore the prospects of wireless sensor networks and propose a design
level framework for developing a smart environment using WSNs, which could be
beneficial for a developing country like Bangladesh. In connection to this, we
also discuss the major aspects of wireless sensor networks.


title: Adaptive optics near-infrared observations of magnetars

abstract:
  <Context>. We report on near-infrared (IR) observations of the three
anomalous X-ray pulsars XTE J1810-197, 1RXS J1708-4009, 1E 1841-045 and the
soft gamma-ray repeater SGR 1900+14, taken with the ESO-VLT, the Gemini, and
the CFHT telescopes. <Aims>. This work is aimed at identifying and/or
confirming the IR counterparts of these magnetars, as well as at measuring
their possible IR variability. <Methods>. In order to perform photometry of
objects as faint as Ks~20, we have used data taken with the largest telescopes,
equipped with the most advanced IR detectors and in most of the cases with
Adaptive Optics devices. The latter are critical to achieve the sharp spatial
accuracy required to pinpoint faint objects in crowded fields. <Results>. We
confirm with high confidence the identification of the IR counterpart to XTE
J1810-197, and its IR variability. For 1E 1841-045 and SGR 1900+14 we propose
two candidate IR counterparts based on the detection of IR variability. For
1RXS J1708-4009 we show that none of the potential counterparts within the
source X-ray error circle can be yet convincingly associated with this AXP.
<Conclusions>. The IR variability of the AXP XTE J1810-197 does not follow the
same monotonic decrease of its post-outburst X-ray emission. Instead, the IR
variability appears more similar to the one observed in radio band, although
simultaneous IR and radio observations are crucial to draw any conclusion in
this respect. For 1E 1841-045 and SGR 1900+14, follow-up observations are
needed to confirm our proposed candidates with higher confidence.


title: Developing an Efficient DMCIS with Next-Generation Wireless Networks

abstract:
  The impact of extreme events across the globe is extraordinary which
continues to handicap the advancement of the struggling developing societies
and threatens most of the industrialized countries in the globe. Various fields
of Information and Communication Technology have widely been used for efficient
disaster management; but only to a limited extent though, there is a tremendous
potential for increasing efficiency and effectiveness in coping with disasters
with the utilization of emerging wireless network technologies. Early warning,
response to the particular situation and proper recovery are among the main
focuses of an efficient disaster management system today. Considering these
aspects, in this paper we propose a framework for developing an efficient
Disaster Management Communications and Information System (DMCIS) which is
basically benefited by the exploitation of the emerging wireless network
technologies combined with other networking and data processing technologies.


title: Secure Clustering in DSN with Key Predistribution and WCDS

abstract:
  This paper proposes an efficient approach of secure clustering in distributed
sensor networks. The clusters or groups in the network are formed based on
offline rank assignment and predistribution of secret keys. Our approach uses
the concept of weakly connected dominating set (WCDS) to reduce the number of
cluster-heads in the network. The formation of clusters in the network is
secured as the secret keys are distributed and used in an efficient way to
resist the inclusion of any hostile entity in the clusters. Along with the
description of our approach, we present an analysis and comparison of our
approach with other schemes. We also mention the limitations of our approach
considering the practical implementation of the sensor networks.


title:
A Novel and Efficient Bilateral Remote User Authentication Scheme Using
  Smart Cards

abstract:
  This paper proposes a novel remote user authentication scheme using smart
cards which allows both the authentication server (AS) and the user to verify
authenticity of each other. Our scheme is efficient enough to resist the known
attacks that could be launched against remote user authentication process.


title:
Magnetic fields and gas in the cluster-influenced spiral galaxy NGC 4254
  - II. Structures of magnetic fields

abstract:
  The origin of asymmetric radio polarized emission and properties of magnetic
fields in the Virgo Cluster spiral NGC4254 are investigated with help of
"magnetic maps" presenting distributions of different magnetic field components
over the entire galaxy, free of Faraday rotation and projection effects. We
show that the dramatic variation of orientation of magnetic field vectors (from
0deg to more than 40deg) throughout the galaxy cannot arise from the dynamo
process alone, but must be dominated by the effects like density waves and
local gas flows. We determine within the galaxy the relation between the
strength of total magnetic field and the local star-formation rate (SFR) as a
power-law with an index of +0.18+-0.01. We find the opposite sense of relation
of magnetic field regularity with SFR (-0.32+-0.03) and suggest that it results
from efficient production of random field with rising turbulence in the regions
with actively forming stars. The distribution of Faraday rotation measures in
NGC4254 indicates a perturbed axisymmetrical mean-field dynamo mode or a
mixture of axisymmetrical and bisymmetrical ones with regular field directed
outwards the disk, which is contrary to most observed galaxies. The magnetic
fields within two outer magnetic arms (shifted downstream of a density wave)
are strong, up to 13muG in the regular field and 20muG in the total field. Our
modeling of cluster influence on different magnetic field components indicates
that within the outer magnetic arms the dynamo-induced magnetic fields are
modified by stretching and shearing forces rather than by cluster ram pressure.
Those forces, which are likely triggered by the galaxy's gravitational
interaction, produce an anisotropic component of the regular field and enhance
the polarized emission.(abridged)


title:
An Improved Timestamp-Based Password Authentication Scheme Using Smart
  Cards

abstract:
  With the recent proliferation of distributed systems and networking, remote
authentication has become a crucial task in many networking applications.
Various schemes have been proposed so far for the two-party remote
authentication; however, some of them have been proved to be insecure. In this
paper, we propose an efficient timestamp-based password authentication scheme
using smart cards. We show various types of forgery attacks against a
previously proposed timestamp-based password authentication scheme and improve
that scheme to ensure robust security for the remote authentication process,
keeping all the advantages that were present in that scheme. Our scheme
successfully defends the attacks that could be launched against other related
previous schemes. We present a detailed cryptanalysis of previously proposed
Shen et. al scheme and an analysis of the improved scheme to show its
improvements and efficiency.


title:
A Secure Lightweight Approach of Node Membership Verification in Dense
  HDSN

abstract:
  In this paper, we consider a particular type of deployment scenario of a
distributed sensor network (DSN), where sensors of different types and
categories are densely deployed in the same target area. In this network, the
sensors are associated with different groups, based on their functional types
and after deployment they collaborate with one another in the same group for
doing any assigned task for that particular group. We term this sort of DSN as
a heterogeneous distributed sensor network (HDSN). Considering this scenario,
we propose a secure membership verification mechanism using one-way accumulator
(OWA) which ensures that, before collaborating for a particular task, any pair
of nodes in the same deployment group can verify each other-s legitimacy of
membership. Our scheme also supports addition and deletion of members (nodes)
in a particular group in the HDSN. Our analysis shows that, the proposed scheme
could work well in conjunction with other security mechanisms for sensor
networks and is very effective to resist any adversary-s attempt to be included
in a legitimate group in the network.


title:
An Efficient PKC-Based Security Architecture for Wireless Sensor
  Networks

abstract:
  In spite of previous widely held belief of the incompatibility of public key
cryptography (PKC) schemes for wireless sensor networks (WSNs), some recent
works have shown that, PKC based schemes could be implemented for such networks
in some ways. The major challenge of employing a PKC scheme in wireless sensor
network is posed by the limitations of resources of the tiny sensors.
Considering this feature of the sensors, in this paper, we propose an efficient
PKC based security architecture with relatively less resource requirements than
those of the other previously proposed PKC schemes for WSN. Our security
architecture comprises basically of two parts; a key handshaking scheme based
on simple linear operations and the derivation of decryption key by a receiver
node. Our architecture allows both base-station-to-node or node-to-base-station
secure communications, and node-to-node secure communications. Analysis and
simulation results show that, our proposed architecture ensures a good level of
security for communications in the network and could effectively be implemented
using the limited computation, memory and energy budgets of the current
generation sensor nodes.


title:
High-efficiency single photon detector combined with an ultra-small APD
  module and a self-training discriminator for high-speed quantum cryptosystems

abstract:
  A single-photon avalanche detector (SPAD) for high-speed quantum-key
generation has successfully been developed. It has the highest photon detection
repetition frequency and the lowest dark count rate in the world, as a
board-mountable sub-system. The SPAD consists of an ultra-small dual-avalanche
photodiode (APD) module and a novel discriminator. The APD module design is
consistent with cooling capability and high-frequency characteristics. The new
module has a 3 GHz bandwidth enabling 1 GHz gate-pulse repetition. The
bandwidth is extended 15-fold relative to the most wideband peltier cooled APD
module. The discriminator has a self-training mechanism to compensate charge
pulse. Dark count rare of the SPAD is reduced 1/10th relative to the lowest
dark count single photon detector. The SPAD allows 3.2-fold multiplying the
quantum key generation rate in theoretical estimation.


title: On the Quantum Resolution of Cosmological Singularities using AdS/CFT

abstract:
  The AdS/CFT correspondence allows us to map a dynamical cosmology to a dual
quantum field theory living on the boundary of spacetime. Specifically, we
study a five-dimensional model cosmology in type IIB supergravity, where the
dual theory is an unstable deformation of $\N=4$ supersymmetric SU(N) gauge
theory on $\Rbar\times S^3$. A one-loop computation shows that the coupling
governing the instability is asymptotically free, so quantum corrections cannot
turn the potential around. The big crunch singularity in the bulk occurs when a
boundary scalar field runs to infinity, in finite time. Consistent quantum
evolution requires that we impose boundary conditions at infinite scalar field,
i.e. a self-adjoint extension of the system. We find that quantum spreading of
the homogeneous mode of the boundary scalar leads to a natural UV cutoff in
particle production as the wavefunction for the homogeneous mode bounces back
from infinity. However a perturbative calculation indicates that despite this,
the logarithmic running of the boundary coupling governing the instability
generally leads to significant particle production across the bounce. This
prevents the wave packet of the homogeneous boundary scalar to return close to
its initial form. Translating back to the bulk theory, we conclude that a
quantum transition from a big crunch to a big bang is an improbable outcome of
cosmological evolution in this class of five-dimensional models.


title:
Implications of Intermediate Mass Black Hole in globular cluster G1 on
  Dark Matter detection

abstract:
  Recently there has been a growing evidence in favor of the presence of an
Intermediate Mass Black Hole in the globular cluster G1, in Andromeda Galaxy.
In this paper, we explore whether the adiabatic growth in the dark matter
density due to the presence of a black hole could result in an observable gamma
ray signal due to dark matter annihilation in this globular cluster. Starting
from an initial NFW matter profile, with density parameters consistent with G1
observations, we find that indeed, if the spike in the density has been formed
and has survived till present, the signal could be observed by GLAST and
current ACT detectors.


title:
Spontaneously modulated spin textures in a dipolar spinor Bose-Einstein
  condensate

abstract:
  Helical spin textures in a $^{87}$Rb F=1 spinor Bose-Einstein condensate are
found to decay spontaneously toward a spatially modulated structure of spin
domains. This evolution is ascribed to magnetic dipolar interactions that
energetically favor the short-wavelength domains over the long-wavelength spin
helix. This is confirmed by eliminating the dipolar interactions by a sequence
of rf pulses and observing a suppression of the formation of the short-range
domains. This study confirms the significance of magnetic dipole interactions
in degenerate $^{87}$Rb F=1 spinor gases.


title:
Probabilistic Visual Secret Sharing Schemes for Gray-scale images and
  Color images

abstract:
  Visual secrete sharing (VSS) is an encryption technique that utilizes human
visual system in the recovering of the secret image and it does not require any
complex calculation. Pixel expansion has been a major issue of VSS schemes. A
number of probabilistic VSS schemes with minimum pixel expansion have been
proposed for binary secret images. This paper presents a general probabilistic
(k, n)-VSS scheme for gray-scale images and another scheme for color images.
With our schemes, the pixel expansion can be set to a user-defined value. When
this value is 1, there is no pixel expansion at all. The quality of
reconstructed secret images, measured by Average Relative Difference, is
equivalent to Relative Difference of existing deterministic schemes. Previous
probabilistic VSS schemes for black-and-white images with respect to pixel
expansion can be viewed as special cases of the schemes proposed here


title: Island Cosmology in the Landscape

abstract:
  In the eternally inflationary background driven by the metastable vacua of
the landscape, it is possible that some local quantum fluctuations with the
null energy condition violation can be large enough to stride over the barriers
among different vacua, so that create some islands full of radiation in new
vacua, and then these emergently thermalized islands will enter into the
evolution of standard big bang cosmology. In this paper, we calculate the
spectrum of curvature perturbation generated during the emergence of island. We
find that generally the spectrum obtained is nearly scale invariant, which can
be well related to that of slow roll inflation by a simple duality. This in
some sense suggests a degeneracy between their scalar spectra. In addition, we
also simply estimate the non-Gaussianity of perturbation, which is naturally
large, yet, can lie well in the observational bound. The results shown here
indicate that the island emergently thermalized in the landscape can be
consistent with our observable universe.