title: Effective Lagrangian and Quantum Screening in Charged Condensate

abstract:
  A condensate of charged scalars in a neutralizing background of fermions
(e.g., condensed helium-4 nuclei in an electron background in white dwarf
cores) is investigated further. We discuss an effective Lagrangian approach to
this system and show that the strong screening of an electric charge found
previously in arXiv:0806.3692 in a mean-field approximation, is a consequence
of a cancellation due to a phonon. The resulting propagators contain terms that
strongly modify their infrared behavior. Furthermore, we evaluate a one-loop
fermion quantum correction to the screened potential, and find that it is also
suppressed by the phonon subtraction. Therefore, charged impurities (e.g.,
hydrogen or helium-3 nuclei) will be screened efficiently by the condensate.


title:
Spectroscopy of High-Redshift Supernovae from the ESSENCE Project: The
  First Four Years

abstract:
  We present the results of spectroscopic observations from the ESSENCE
high-redshift supernova (SN) survey during its first four years of operation.
This sample includes spectra of all SNe Ia whose light curves were presented by
Miknaitis et al. (2007) and used in the cosmological analyses of Davis et al.
(2007) and Wood-Vasey et al. (2007). The sample represents 273 hours of
spectroscopic observations with 6.5 - 10-m-class telescopes of objects detected
and selected for spectroscopy by the ESSENCE team. We present 174 spectra of
156 objects. Combining this sample with that of Matheson et al. (2005), we have
a total sample of 329 spectra of 274 objects. From this, we are able to
spectroscopically classify 118 Type Ia SNe. As the survey has matured, the
efficiency of classifying SNe Ia has remained constant while we have observed
both higher-redshift SNe Ia and SNe Ia farther from maximum brightness.
Examining the subsample of SNe Ia with host-galaxy redshifts shows that
redshifts derived from only the SN Ia spectra are consistent with redshifts
found from host-galaxy spectra. Moreover, the phases derived from only the SN
Ia spectra are consistent with those derived from light-curve fits. By
comparing our spectra to local templates, we find that the rate of objects
similar to the overluminous SN 1991T and the underluminous SN 1991bg in our
sample are consistent with that of the local sample. We do note, however, that
we detect no object spectroscopically or photometrically similar to SN 1991bg.
Although systematic effects could reduce the high-redshift rate we expect based
on the low-redshift surveys, it is possible that SN 1991bg-like SNe Ia are less
prevalent at high redshift.


title: Morphological Composition of z~0.4 groups: The site of S0 formation

abstract:
  The low redshift Universe (z<~0.5) is not a dull place. Processes leading to
the suppression of star formation and morphological transformation are
prevalent: this is particularly evident in the dramatic upturn in the fraction
of S0-type galaxies in clusters. However, until now, the process and
environment of formation has remained unidentified. We present a HST-based
morphological analysis of galaxies in the redshift-space selected group and
field environments at z~0.4. Groups contain a much higher fraction of S0s at
fixed luminosity than the lower density field, with >99.999% confidence. Indeed
the S0 fraction in groups is at least as high as in z~0.4 clusters and X-ray
selected groups, which have more luminous Intra Group Medium (IGM). An 97%
confident excess of S0s at >=0.3Mpc from the group centre at fixed luminosity,
tells us that formation is not restricted to, and possibly even avoids, the
group cores. Interactions with a bright X-ray emitting IGM cannot be important
for the formation of the majority of S0s in the Universe. In contrast to S0s,
the fraction of elliptical galaxies in groups at fixed luminosity is similar to
the field, whilst the brightest ellipticals are strongly enhanced towards the
group centres (>99.999% confidence within 0.3Mpc). We conclude that the group
and sub-group environments must be dominant for the formation of S0 galaxies,
and that minor mergers, galaxy harassment and tidal interactions are the most
likely responsible mechanisms. This has implications not only for the inferred
pre-processing of cluster galaxies, but also for the global morphological and
star formation budget of galaxies: as hierarchical clustering progresses, more
galaxies will be subject to these transformations as they enter the group
environment.


title:
Three dimensional magnetic field structure of six parsec-scale active
  galactic nuclei jets

abstract:
  The parsec-scale Faraday rotation measure (RM) distribution of six "blazars"
is investigated using multi-frequency (4.6--43 GHz) polarization observations
taken on 2006 July 2 with the VLBA. Analysis of the RM provides the direction
of the line-of-sight (LoS) magnetic field component, as well as the intrinsic
2-D polarization distribution on the plane of the sky. Our results show that
the magnitude of the core RM increases systematically with frequency, and is
well described by a power-law, where |RM_{core}| \propto \nu^a. Our measured
values of $a$ vary from 0.9 to 3.8, providing information on the assumed
power-law fall-off in the electron density with distance from the central
engine for each source. RM gradients were detected across the jets of three
sources, supporting the presence of helical magnetic fields in a sheath or
boundary layer surrounding their jets. We find a bi-modal distribution of the
intrinsic jet polarization orientation; either aligned or orthogonal to the jet
direction. A helical magnetic field geometry can neatly explain both the
bi-model distribution of the jet polarization orientation and the ordered
polarization structure detected on these scales. In half the sources, we find
that the core RM changes sign with distance from the central engine. We provide
an explanation for this by considering a boundary layer of Faraday rotating
material threaded by a helical magnetic field, where bends in the relativistic
jet or accelerating/decelerating flows give rise to changes in the dominant LoS
components of the magnetic field, which in turn gives rise to different signs
of the RM. (abridged)


title: Quiver Topology and RG Dynamics

abstract:
  Renormalization group flows of quiver gauge theories play a central role in
determining the low-energy properties of string vacua. We demonstrate that
useful predictions about the RG dynamics of a quiver gauge theory may be
extracted from the global structure of its quiver diagram. For quiver theories
of a certain type, we develop an efficient and practical method for determining
which superpotential deformations generate a flow to an interacting conformal
fixed point.


title:
Efficient discrete-time simulations of continuous-time quantum query
  algorithms

abstract:
  The continuous-time query model is a variant of the discrete query model in
which queries can be interleaved with known operations (called "driving
operations") continuously in time. Interesting algorithms have been discovered
in this model, such as an algorithm for evaluating nand trees more efficiently
than any classical algorithm. Subsequent work has shown that there also exists
an efficient algorithm for nand trees in the discrete query model; however,
there is no efficient conversion known for continuous-time query algorithms for
arbitrary problems.
  We show that any quantum algorithm in the continuous-time query model whose
total query time is T can be simulated by a quantum algorithm in the discrete
query model that makes O[T log(T) / log(log(T))] queries. This is the first
upper bound that is independent of the driving operations (i.e., it holds even
if the norm of the driving Hamiltonian is very large). A corollary is that any
lower bound of T queries for a problem in the discrete-time query model
immediately carries over to a lower bound of \Omega[T log(log(T))/log (T)] in
the continuous-time query model.


title: Multi-Component Dark Matter

abstract:
  We explore multi-component dark matter models where the dark sector consists
of multiple stable states with different mass scales, and dark forces coupling
these states further enrich the dynamics. The multi-component nature of the
dark matter naturally arises in supersymmetric models, where both R parity and
an additional symmetry, such as a $Z_2$, is preserved. We focus on a particular
model where the heavier component of dark matter carries lepton number and
annihilates mostly to leptons. The heavier component, which is essentially a
sterile neutrino, naturally explains the PAMELA, ATIC and synchrotron signals,
without an excess in antiprotons which typically mars other models of weak
scale dark matter. The lighter component, which may have a mass from a GeV to a
TeV, may explain the DAMA signal, and may be visible in low threshold runs of
CDMS and XENON, which search for light dark matter.


title: Anomalous Ferromagnetism in TbMnO3 Thin Films

abstract:
  Magnetometry, x-ray, and neutron scattering have been used to study the
structural and magnetic properties of a TbMnO3 thin film grown on a [001]
SrTiO3 substrate by pulsed laser deposition. Although bulk TbMnO3 is a low
temperature antiferromagnet, magnetometry measurements indicate the presence of
low temperature ferromagnetism. Depth profiling by x-ray and polarized neutron
reflectometry reveals a net sample magnetization that is commensurate with the
film thickness, indicating that the observed ferromagnetism is not due to an
altered surface phase (such as Mn3O4), or external impurities that might give
rise to an artificial magnetic signal. Instead, these results show that the
ferromagnetism is an intrinsic property of the TbMnO3 film.


title: The Lorentz Condition is Equivalent to Maxwell Equations

abstract:
  It is shown that the Lorentz condition which is a conservation law on the
electromagnetic four-vector-density A, plus the Lorentz transformation, taken
together, are equivalent to the microscopic Maxwell's equations.


title:
Translation-finite sets, and weakly compact derivations from
  $\lp{1}(\Z_+)$ to its dual

abstract:
  We characterize those derivations from the convolution algebra
$\ell^1({\mathbb Z}_+)$ to its dual which are weakly compact. In particular, we
provide examples which are weakly compact but not compact. The characterization
is combinatorial, in terms of "translation-finite" subsets of ${\mathbb Z}_+$,
and we investigate how this notion relates to other notions of "smallness" for
infinite subsets of ${\mathbb Z}_+$. In particular, we show that a set of
strictly positive Banach density cannot be translation-finite; the proof has a
Ramsey-theoretic flavour.


title:
Ironing out primordial temperature fluctuations with polarisation:
  optimal detection of cosmic structure imprints

abstract:
  Secondary anisotropies of the cosmic microwave background (CMB) can be
detected by using the cross-correlation between the large-scale structure (LSS)
and the CMB temperature fluctuations. In such studies, chance correlations of
primordial CMB fluctuations with the LSS are the main source of uncertainty. We
present a method for reducing this noise by exploiting information contained in
the polarisation of CMB photons. The method is described in general terms and
then applied to our recently proposed optimal method for measuring the
integrated Sachs-Wolfe (ISW) effect. We obtain an expected signal-to-noise
ratio of up to 8.5. This corresponds to an enhancement of the signal-to-noise
by 23 per cent as compared to the standard method for ISW detection, and by 16
per cent w.r.t. our recently proposed method, both for the best-case scenario
of having perfect (noiseless) CMB and LSS data.


title:
Single-Scattering Optical Tomography: Simultaneous Reconstruction of
  Scattering and Absorption

abstract:
  We demonstrate that simultaneous reconstruction of scattering and absorption
of a mesoscopic system using angularly-resolved measurements of scattered light
intensity is possible. Image reconstruction is realized based on the algebraic
inversion of a generalized Radon transform relating the scattering and
absorption coefficients of the medium to the measured light intensity and
derived using the single-scattering approximation to the radiative transport
equation.


title:
On the special values of certain Rankin-Selberg L-functions and
  applications to odd symmetric power L-functions of modular forms

abstract:
  We prove an algebraicity result for the central critical value of certain
Rankin-Selberg L-functions for GL(n) x GL(n-1). This is a generalization and
refinement of some results of Harder, Kazhdan-Mazur-Schmidt, Mahnkopf, and
Kasten-Schmidt. As an application of this result, we prove algebraicity results
for certain critical values of the fifth and the seventh symmetric power
L-functions attached to a holomorphic cusp form. Assuming Langlands
functoriality one can prove similar algebraicity results for the special values
of any odd symmetric power L-function. We also prove a conjecture of Blasius
and Panchishkin on twisted L-values in some cases. We comment on the
compatibility of our results with Deligne's conjecture on the critical values
of motivic L-functions. These results, as in the above mentioned works, are, in
general, based on a nonvanishing hypothesis on certain archimedean integrals.


title: Synthesis and physical properties of $\rm\bf LaO_{1-x}F_xFeAs$

abstract:
  We have prepared the newly discovered Fe-based superconducting material $\rm
LaO_{1-x}F_xFeAs$ ($0\leq x\leq 0.2$) in polycrystalline form and have
investigated the samples by means of structural, thermodynamic and transport
measurements. Our investigations reveal a non superconducting phase at $0\leq
x\lesssim0.04$ which for $x=0$ is characterized by a structural transition
towards an orthorhombic distortion at $T_s\approx 160$ K and antiferromagnetic
spin order at $T_N\approx138$ K. Both transitions lead to strong anomalies in
various transport properties as well as in magnetization and in specific heat.
Remarkably, the transition temperatures are only weakly doping dependent up
$x\lesssim 0.04$. However, the transitions are abruptly suppressed at
$x\geq0.05$ in favour of a superconducting phase with a critical temperature
$T_c\gtrsim 20$ K. Upon further increasing the F-doping $T_c$ increases up to a
maximum of $T_c=26.8$ K at $x=0.1$ which is followed by a decrease down to
$T_c\approx10$ K at $x\geq0.15$.


title: Alternating Euler sums at the negative integers

abstract:
  We study three special Dirichlet series, two of them alternating, related to
the Riemann zeta function. These series are shown to have extensions to the
entire complex plane and we find their values at the negative integers (or
residues at poles). These values are given in terms of Bernoulli and Euler
numbers.


title: Where to place a hole to achieve a maximal escape rate

abstract:
  A natural question of how the survival probability depends upon a position of
a hole was seemingly never addressed in the theory of open dynamical systems.
We found that this dependency could be very essential. The main results are
related to the holes with equal sizes (measure) in the phase space of strongly
chaotic maps. Take in each hole a periodic point of minimal period. Then the
faster escape occurs through the hole where this minimal period assumes its
maximal value. The results are valid for all finite times (starting with the
minimal period) which is unusual in dynamical systems theory where typically
statements are asymptotic when time tends to infinity. It seems obvious that
the bigger the hole is the bigger is the escape through that hole. Our results
demonstrate that generally it is not true, and that specific features of the
dynamics may play a role comparable to the size of the hole.


title: The Hamiltonian description of incompressible fluid ellipsoids

abstract:
  We construct the noncanonical Poisson bracket associated with the phase space
of first order moments of the velocity field and quadratic moments of the
density of a fluid with a free- boundary, constrained by the condition of
incompressibility. Two methods are used to obtain the bracket, both based on
Dirac's procedure for incorporating constraints. First, the Poisson bracket of
moments of the unconstrained Euler equations is used to construct a Dirac
bracket, with Casimir invariants corresponding to volume preservation and
incompressibility. Second, the Dirac procedure is applied directly to the
continuum, noncanonical Poisson bracket that describes the compressible Euler
equations, and the moment reduction is applied to this bracket. When the
Hamiltonian can be expressed exactly in terms of these moments, a closure is
achieved and the resulting finite-dimensional Hamiltonian system provides exact
solutions of Euler's equations. This is shown to be the case for the classical,
incompressible Riemann ellipsoids, which have velocities that vary linearly
with position and have constant density within an ellipsoidal boundary. The
incompressible, noncanonical Poisson bracket differs from its counterpart for
the compressible case in that it is not of Lie-Poisson form.


title: Continuous Wavelets on Compact Manifolds

abstract:
  Let $\bf M$ be a smooth compact oriented Riemannian manifold, and let
$\Delta_{\bf M}$ be the Laplace-Beltrami operator on ${\bf M}$. Say $0 \neq f
\in \mathcal{S}(\RR^+)$, and that $f(0) = 0$. For $t > 0$, let $K_t(x,y)$
denote the kernel of $f(t^2 \Delta_{\bf M})$. We show that $K_t$ is
well-localized near the diagonal, in the sense that it satisfies estimates akin
to those satisfied by the kernel of the convolution operator $f(t^2\Delta)$ on
$\RR^n$. We define continuous ${\cal S}$-wavelets on ${\bf M}$, in such a
manner that $K_t(x,y)$ satisfies this definition, because of its localization
near the diagonal. Continuous ${\cal S}$-wavelets on ${\bf M}$ are analogous to
continuous wavelets on $\RR^n$ in $\mathcal{S}(\RR^n)$. In particular, we are
able to characterize the H$\ddot{o}$lder continuous functions on ${\bf M}$ by
the size of their continuous ${\mathcal{S}}-$wavelet transforms, for
H$\ddot{o}$lder exponents strictly between 0 and 1. If $\bf M$ is the torus
$\TT^2$ or the sphere $S^2$, and $f(s)=se^{-s}$ (the ``Mexican hat''
situation), we obtain two explicit approximate formulas for $K_t$, one to be
used when $t$ is large, and one to be used when $t$ is small.


title:
The Schrodinger equation with Hulthen potential plus ring-shaped
  potential

abstract:
  We present the solutions of the Schr$\ddot{o}$dinger equation with the
Hulth$\acute{e}$n potential plus ring-shape potential for $\ell\neq 0$ states
within the framework of an exponential approximation of the centrifugal
potential.Solutions to the corresponding angular and radial equations are
obtained in terms of special functions using the conventional Nikiforov-Uvarov
method. The normalization constant for the Hulth$\acute{e}$n potential is also
computed.


title:
Temperature Dependence of Interlayer Magnetoresistance in Anisotropic
  Layered Metals

abstract:
  Studies of interlayer transport in layered metals have generally made use of
zero temperature conductivity expressions to analyze angle-dependent
magnetoresistance oscillations (AMRO). However, recent high temperature AMRO
experiments have been performed in a regime where the inclusion of finite
temperature effects may be required for a quantitative description of the
resistivity. We calculate the interlayer conductivity in a layered metal with
anisotropic Fermi surface properties allowing for finite temperature effects.
We find that resistance maxima are modified by thermal effects much more
strongly than resistance minima. We also use our expressions to calculate the
interlayer resistivity appropriate to recent AMRO experiments in an overdoped
cuprate which led to the conclusion that there is an anisotropic, linear in
temperature contribution to the scattering rate and find that this conclusion
is robust.


title: External gates and transport in biased bilayer graphene

abstract:
  We formulate a theory of transport in graphene bilayers in the weak momentum
scattering regime in such a way as to take into account contributions to the
electrical conductivity to leading and next-to-leading order in the scattering
potential. The response of bilayers to an electric field cannot be regarded as
a sum of terms due to individual layers. Rather, interlayer tunneling and
coherence between positive- and negative-energy states give the main
contributions to the conductivity. At low energies, the dominant effect of
scattering on transport comes from scattering within each energy band, yet a
simple picture encapsulating the role of collisions in a set of scattering
times is not applicable. Coherence between positive- and negative-energy states
gives, as in monolayers, a term in the conductivity which depends on the order
of limits. The application of an external gate, which introduces a gap between
positive- and negative-energy states, does not affect transport. Nevertheless
the solution to the kinetic equation in the presence of such a gate is very
revealing for transport in both bilayers and monolayers.


title:
Log canonical thresholds on smooth varieties: the Ascending Chain
  Condition

abstract:
  Building on results of Koll\'ar, we prove Shokurov's ACC Conjecture for log
canonical thresholds on smooth varieties, and more generally, on varieties with
quotient singularities.


title: Probing Supersymmetry With Third-Generation Cascade Decays

abstract:
  The chiral structure of supersymmetric particle couplings involving third
generation Standard Model fermions depends on left-right squark and slepton
mixings as well as gaugino-higgsino mixings. The shapes and intercorrelations
of invariant mass distributions of a first or second generation lepton with
bottoms and taus arising from adjacent branches of SUSY cascade decays are
shown to be a sensitive probe of this chiral structure. All possible cascade
decays that can give rise to such correlations within the MSSM are considered.
For bottom-lepton correlations the distinctive structure of the invariant mass
distributions distinguishes between decays originating from stop or sbottom
squarks through either an intermediate chargino or neutralino. For decay
through a chargino the spins of the stop and chargino are established by the
form of the distribution. When the bottom charge is signed through soft muon
tagging, the structure of the same-sign and opposite-sign invariant mass
distributions depends on a set function of left-right and gaugino-higgsino
mixings, as well as establishes the spins of all the superpartners in the
sequential two-body cascade decay. Tau-lepton and tau-tau invariant mass
distributions arising from MSSM cascade decays are likewise systematically
considered with particular attention to their dependence on tau polarization.
All possible tau-lepton and tau-tau distributions are plotted using a
semi-analytic model for hadronic one-prong taus. Algorithms for fitting tau-tau
and tau-lepton distributions to data are suggested.


title: Multigrid solver for axisymmetrical 2D fluid equations

abstract:
  We have developed an efficient algorithm for steady axisymmetrical 2D fluid
equations. The algorithm employs multigrid method as well as standard implicit
discretization schemes for systems of partial differential equations. Linearity
of the multigrid method with respect to the number of grid points allowed us to
use $256\times 256$ grid, where we could achieve solutions in several minutes.
Time limitations due to nonlinearity of the system are partially avoided by
using multi level grids(the initial solution on $256\times 256$ grid was
extrapolated steady solution from $128\times 128$ grid which allowed using
"long" integration time steps). The fluid solver may be used as the basis for
hybrid codes for DC discharges.


title: Importance Sampling of Word Patterns in DNA and Protein Sequences

abstract:
  Monte Carlo methods can provide accurate p-value estimates of word counting
test statistics and are easy to implement. They are especially attractive when
an asymptotic theory is absent or when either the search sequence or the word
pattern is too short for the application of asymptotic formulae. Naive direct
Monte Carlo is undesirable for the estimation of small probabilities because
the associated rare events of interest are seldom generated. We propose instead
efficient importance sampling algorithms that use controlled insertion of the
desired word patterns on randomly generated sequences. The implementation is
illustrated on word patterns of biological interest: Palindromes and inverted
repeats, patterns arising from position specific weight matrices and
co-occurrences of pairs of motifs.


title: Four loop twist two, BFKL, wrapping and strings

abstract:
  The anomalous dimensions of twist two operators have to satisfy certain
consistency requirements derived from BFKL. For N=4 SYM it was shown that at
four loops, the anomalous dimensions derived from the all-loop asymptotic Bethe
ansatz do not pass this test. In this paper we obtain the remaining wrapping
part of these anomalous dimensions from string theory and show that these
contributions exactly cure the problem and lead to agreement with both LO and
NLO BFKL expectations.


title: Fast tuning of superconducting microwave cavities

abstract:
  Photons are fundamental excitations of the electromagnetic field and can be
captured in cavities. For a given cavity with a certain size, the fundamental
mode has a fixed frequency {\it f} which gives the photons a specific "color".
The cavity also has a typical lifetime $\tau$, which results in a finite
linewidth $\delta${\it f}. If the size of the cavity is changed fast compared
to $\tau$, and so that the frequency change $\Delta${\it f} $\gg \delta${\it
f}, then it is possible to change the "color" of the captured photons. Here we
demonstrate superconducting microwave cavities, with tunable effective lengths.
The tuning is obtained by varying a Josephson inductance at one end of the
cavity. We show data on four different samples and demonstrate tuning by
several hundred linewidths in a time $\Delta t \ll \tau$. Working in the few
photon limit, we show that photons stored in the cavity at one frequency will
leak out from the cavity with the new frequency after the detuning. The
characteristics of the measured devices make them suitable for different
applications such as dynamic coupling of qubits and parametric amplification.


title: Understanding Terrorist Organizations with a Dynamic Model

abstract:
  Terrorist organizations change over time because of processes such as
recruitment and training as well as counter-terrorism (CT) measures, but the
effects of these processes are typically studied qualitatively and in
separation from each other. Seeking a more quantitative and integrated
understanding, we constructed a simple dynamic model where equations describe
how these processes change an organization's membership. Analysis of the model
yields a number of intuitive as well as novel findings. Most importantly it
becomes possible to predict whether counter-terrorism measures would be
sufficient to defeat the organization. Furthermore, we can prove in general
that an organization would collapse if its strength and its pool of foot
soldiers decline simultaneously. In contrast, a simultaneous decline in its
strength and its pool of leaders is often insufficient and short-termed. These
results and other like them demonstrate the great potential of dynamic models
for informing terrorism scholarship and counter-terrorism policy making.


title: Towards Proving Legendre's Conjecture

abstract:
  Legendre's conjecture states that there is a prime number between n^2 and
(n+1)^2 for every positive integer n. We consider the following question : for
all integer n>1 and a fixed integer k<=n does there exist a prime number such
that kn < p < (k+1)n ? Bertrand-Chebyshev theorem answers this question
affirmatively for k=1. A positive answer for k=n would prove Legendre's
conjecture. In this paper, we show that one can determine explicitly a number
N(k) such that for all n >= N(k), there is at least one prime between kn and
(k+1)n. Our proof is based on Erdos's proof of Bertrand-Chebyshev theorem and
uses elementary combinatorial techniques without appealing to the prime number
theorem.


title:
Tetrahedron equations, boundary states and hidden structure of
  U_q(D_n^1)

abstract:
  Simple periodic 3d->2d compactification of the tetrahedron equations gives
the Yang-Baxter equations for various evaluation representations of U_q(sl_n).
In this paper we construct an example of fixed non-periodic 3d boundary
conditions producing a set of Yang-Baxter equations for U_q(D_n^1). These
boundary conditions resemble a fusion in hidden direction.


title: Non-Hermitian Adiabatic Quantum Optimization

abstract:
  We propose a novel non-Hermitian adiabatic quantum optimization algorithm.
One of the new ideas is to use a non-Hermitian auxiliary "initial'' Hamiltonian
that provides an effective level repulsion for the main Hamiltonian. This
effect enables us to develop an adiabatic theory which determines ground state
much more efficiently than Hermitian methods.


title: Laumon Spaces and the Calogero-Sutherland Integrable System

abstract:
  This paper contains a proof of a conjecture of Braverman concerning Laumon
quasiflag spaces. We consider the generating function Z(m), whose coefficients
are the integrals of the equivariant Chern polynomial (with variable m) of the
tangent bundles of the Laumon spaces. We prove Braverman's conjecture, which
states that Z(m) coincides with the eigenfunction of the Calogero-Sutherland
hamiltonian, up to a simple factor which we specify. This conjecture was
inspired by the work of Nekrasov in the affine \hat{sl}_n setting, where a
similar conjecture is still open.


title: Convergence to Weighted Fractional Brownian Sheets

abstract:
  We define weighted fractional Brownian sheets, which are a class of Gaussian
random fields with four parameters that include fractional Brownian sheets as
special cases, and we give some of their properties. We show that for certain
values of the parameters the weighted fractional Brownian sheets are obtained
as limits in law of occupation time fluctuations of a stochastic particle
model. In contrast with some known approximations of fractional Brownian sheets
which use a kernel in a Volterra type integral representation of fractional
Brownian motion with respect to ordinary Brownian motion, our approximation
does not make use of a kernel.


title: Extreme tunability of interactions in a $^7$Li Bose-Einstein condensate

abstract:
  We use a Feshbach resonance to tune the scattering length a of a
Bose-Einstein condensate of 7Li in the |F = 1, m_F = 1> state. Using the
spatial extent of the trapped condensate we extract a over a range spanning 7
decades from small attractive interactions to extremely strong repulsive
interactions. The shallow zero-crossing in the wing of the Feshbach resonance
enables the determination of a as small as 0.01 Bohr radii. In this regime,
evidence of the weak anisotropic magnetic dipole interaction is obtained by
comparison with different trap geometries.


title:
Study of the Growth of Entropy Modes in MSSM Flat Directions Decay:
  Constraints on the Parameter Space

abstract:
  We study how the resonant decay of moduli fields arising in the Minimal
Supersymmetric Standard Model (MSSM) could affect large scale curvature
perturbations in the early universe. It has been known for some time that the
presence of entropy perturbations in a multi-component system can act as seeds
for the curvature perturbations on all scales. These entropy perturbations
could be amplified exponentially if one of the moduli decays via stochastic
resonance, affecting the curvature power spectrum in the process. By imposing
the COBE normalization on this power spectrum, one could put constraints on the
masses and couplings of the underlying particle physics model without having to
rely on collider experiments. We discuss in detail the case of the MSSM but
this method could be applied to other theories beyond the Standard Model.


title: Learning Class-Level Bayes Nets for Relational Data

abstract:
  Many databases store data in relational format, with different types of
entities and information about links between the entities. The field of
statistical-relational learning (SRL) has developed a number of new statistical
models for such data. In this paper we focus on learning class-level or
first-order dependencies, which model the general database statistics over
attributes of linked objects and links (e.g., the percentage of A grades given
in computer science classes). Class-level statistical relationships are
important in themselves, and they support applications like policy making,
strategic planning, and query optimization. Most current SRL methods find
class-level dependencies, but their main task is to support instance-level
predictions about the attributes or links of specific entities. We focus only
on class-level prediction, and describe algorithms for learning class-level
models that are orders of magnitude faster for this task. Our algorithms learn
Bayes nets with relational structure, leveraging the efficiency of single-table
nonrelational Bayes net learners. An evaluation of our methods on three data
sets shows that they are computationally feasible for realistic table sizes,
and that the learned structures represent the statistical information in the
databases well. After learning compiles the database statistics into a Bayes
net, querying these statistics via Bayes net inference is faster than with SQL
queries, and does not depend on the size of the database.


title: Pairing in hot rotating nuclei

abstract:
  Nuclear pairing properties are studied within an approach that includes the
quasiparticle-number fluctuation (QNF) and coupling to the quasiparticle-pair
vibrations at finite temperature and angular momentum. The formalism is
developed to describe non-collective rotations about the symmetry axis. The
numerical calculations are performed within a doubly-folded equidistant
multilevel model as well as several realistic nuclei. The results obtained for
the pairing gap, total energy and heat capacity show that the QNF smoothes out
the sharp SN phase transition and leads to the appearance of a thermally
assisted pairing gap in rotating nuclei at finite temperature. The corrections
due to the dynamic coupling to SCQRPA vibrations and particle-number projection
are analyzed. The effect of backbending of the momentum of inertia as a
function of squared angular velocity is also discussed.


title:
Transgression and twisted anomaly cancellation formulas on odd
  dimensional manifolds

abstract:
  We compute the transgressed forms of some modularly invariant characteristic
forms,which are related to the twisted elliptic genera. We study the modularity
properties of these secondary characteristic forms and relations among them. We
also get some twisted anomaly cancellation formulas on some odd dimensional
manifolds.


title:
On the existence of embeddings into modules of finite homological
  dimensions

abstract:
  Let R be a commutative Noetherian local ring. We show that R is Gorenstein if
and only if every finitely generated R-module can be embedded in a finitely
generated R-module of finite projective dimension. This extends a result of
Auslander and Bridger to rings of higher Krull dimension, and it also improves
a result due to Foxby where the ring is assumed to be Cohen-Macaulay.


title: A Local Relative Trace Formula for F*\SL(2,F)

abstract:
  In this note, we derive explicitly the local relative trace formula for the
symmetric space F*\SL(2,F) at the level of Lie algebras, where F is a p-adic
field of residue characteristic greater than two and F* is the set of
invertible elements in F. This is perhaps one of the simplest non-trivial
analogs of the trace formula, and also a motivating example for the author's
work (in preparation) on the relative trace formula.


title: Partial Correlation Estimation by Joint Sparse Regression Models

abstract:
  In this paper, we propose a computationally efficient approach --
space(Sparse PArtial Correlation Estimation)-- for selecting non-zero partial
correlations under the high-dimension-low-sample-size setting. This method
assumes the overall sparsity of the partial correlation matrix and employs
sparse regression techniques for model fitting. We illustrate the performance
of space by extensive simulation studies. It is shown that space performs well
in both non-zero partial correlation selection and the identification of hub
variables, and also outperforms two existing methods. We then apply space to a
microarray breast cancer data set and identify a set of hub genes which may
provide important insights on genetic regulatory networks. Finally, we prove
that, under a set of suitable assumptions, the proposed procedure is
asymptotically consistent in terms of model selection and parameter estimation.


title:
Asymptotically AdS_3 Solutions to Topologically Massive Gravity at
  Special Values of the Coupling Constants

abstract:
  We study exact solutions to Cosmological Topologically Massive Gravity (CTMG)
coupled to Topologically Massive Electrodynamics (TME) at special values of the
coupling constants. For the particular case of the so called chiral point
l\mu_G=1, vacuum solutions (with vanishing gauge field) are exhibited. These
correspond to a one-parameter deformation of GR solutions, and are continuously
connected to the extremal Ba\~nados-Teitelboim-Zanelli black hole (BTZ) with
bare constants J=-lM. At the chiral point this extremal BTZ turns out to be
massless, and thus it can be regarded as a kind of ground state. Although the
solution is not asymptotically AdS_3 in the sense of Brown-Henneaux boundary
conditions, it does obey the weakened asymptotic recently proposed by Grumiller
and Johansson. Consequently, we discuss the holographic computation of the
conserved charges in terms of the stress-tensor in the boundary. For the case
where the coupling constants satisfy the relation l\mu_G=1+2l\mu_E,
electrically charged analogues to these solutions exist. These solutions are
asymptotically AdS_3 in the strongest sense, and correspond to a logarithmic
branch of selfdual solutions previously discussed in the literature.


title:
Horizon Complementarity and Casimir Violations of the Null Energy
  Condition

abstract:
  The principle of horizon complementarity is an attempt to extend ideas about
black hole complementarity to all horizons, including cosmological ones. The
idea is that the degrees of freedom necessary to describe the interior of the
cosmic horizon of one observer in a given universe are in fact sufficient to
account for the physics of that entire universe: the remainder is just a set of
redundant copies of the interior of a single cosmic horizon. These copies must
be factored out, just as one has to factor out gauge redundancies to identify
the true degrees of freedom in gauge theory. Motivated by the observation that
quantum cosmology favours compactified negatively curved spatial sections, we
propose to use such geometries to implement horizon complementarity for eternal
Inflation. We point out that the "effective finiteness" of such universes has
important consequences for physics inside the observer's horizon: there is a
non-local effect, represented by a Casimir energy. We use our proposed
interpretation of complementarity to constrain the gravitational Casimir
coupling in two very different ways; the result is an explicit prediction for
the value of the coupling.


title: Conservation rules for entanglement transfer between qubits

abstract:
  We consider an entangled but non-interacting qubit pair a_{1} and b_{1} that
are independently coupled to a set of local qubit systems, a_{I} and b_{J}, of
0-bit value, respectively. We derive rules for the transfer of entanglement
from the pair a_{1}-b_{1} to an arbitrary pair a_{I}-b_{J}, for the case of
qubit-number conserving local interactions. It is shown that the transfer rule
depends strongly on the initial entangled state. If the initial entanglement is
in the form of the Bell state corresponding to anti-correlated qubits, the sum
of the square of the non-local pairwise concurrences is conserved. If the
initial state is the Bell state with correlated qubits, this sum can be
reduced, even to zero in some cases, to reveal a complete and abrupt loss of
all non-local pairwise entanglement. We also identify that for the nonlocal
bipartitions A-b_{J} involving all qubits at one location, with one qubit b_{J}
at the other location, the concurrences satisfies a simple addition rule for
both cases of the Bell states, that the sum of the square of the nonlocal
concurrences is conserved.


title: Dark Energy Content of Nonlinear Electromagnetism

abstract:
  Quasi-constant external fields in nonlinear electromagnetism generate a
contribution to the energy-momentum tensor with the form of dark energy. To
provide a thorough understanding of the origin and strength of the effects, we
undertake a complete theoretical and numerical study of the energy-momentum
tensor $T^{\mu\nu}$ for nonlinear electromagnetism. The Euler-Heisenberg
nonlinearity due to quantum fluctuations of spinor and scalar matter fields is
considered and contrasted with the properties of classical nonlinear
Born-Infeld electromagnetism. We also address modifications of charged particle
kinematics by strong background fields.


title: Frequency-dependent Chemolocation and Chemotactic Target Selection

abstract:
  Chemotaxis is typically modeled in the context of cellular motion towards a
static, exogenous source of chemoattractant. Here, we propose a time-dependent
mechanism of chemotaxis in which a self-propelled particle ({\it e.g.}, a cell)
releases a chemical that diffuses to fixed particles (targets) and signals the
production of a second chemical by these targets. The particle then moves up
concentration gradients of this second chemical, analogous to diffusive
echolocation. When one target is present, we describe probe release strategies
that optimize travel of the cell to the target. In the presence of multiple
targets, the one selected by the cell depends on the strength and,
interestingly, on the frequency of probe chemical release. Although involving
an additional chemical signaling step, our chemical ``pinging'' hypothesis
allows for greater flexibility in regulating target selection, as seen in a
number of physical or biological realizations.


title:
Measurement of superluminal phase and group velocities of Bessel beams
  in free space

abstract:
  We report on an interferometry-based measurement of the phase and group
velocities of optical Bessel beams, providing confirmation of their
superluminal character in the non-diffractive region. The measurements were
performed in free space with a continuous wave laser and femtosecond pulses for
phase and group velocities respectively. The Bessel beams were produced using a
conical mirror.


title: AV-Courant algebroids and generalized CR structures

abstract:
  We construct a generalization of Courant algebroids which are classified by
the third cohomology group $H^3(A,V)$, where $A$ is a Lie Algebroid, and $V$ is
an $A$-module. We see that both Courant algebroids and $\mathcal{E}^1(M)$
structures are examples of them. Finally we introduce generalized CR structures
on a manifold, which are a generalization of generalized complex structures,
and show that every CR structure and contact structure is an example of a
generalized CR structure.


title: Interaction and excitonic insulating transition in graphene

abstract:
  The strong long-range Coulomb interaction between massless Dirac fermions in
graphene can drive a semimetal-insulator transition. We show that this
transition is strongly suppressed when the Coulomb interaction is screened by
such effects as disorder, thermal fluctuation, doping, and finite volume. It is
completely suppressed once the screening factor $\mu$ is beyond a threshold
$\mu_{c}$ even for infinitely strong coupling. However, such transition is
still possible if there is an additional strong contact four-fermion
interaction. The differences between screened and contact interactions are also
discussed.


title:
Complete Characterization of Mixing Time for the Continuous Quantum Walk
  on the Hypercube with Markovian Decoherence Model

abstract:
  The n-dimensional hypercube quantum random walk (QRW) is a particularily
appealing example of a quantum walk because it has a natural implementation on
a register on $n$ qubits. However, any real implementation will encounter
decoherence effects due to interactions with uncontrollable degrees of freedom.
We present a complete characterization of the mixing properties of the
hypercube QRW under a physically relevant Markovian decoherence model. In the
local decoherence model considered the non-unitary dynamics are modeled as a
sum of projections on individual qubits to an arbitrary direction on the Bloch
sphere. We prove that there is always classical (asymptotic) mixing in this
model and specify the conditions under which instantaneous mixing
\textit{always} exists. And we show that the latter mixing property, as well as
the classical mixing time, depend heavily on the exact environmental
interaction and its strength. Therefore, algorithmic applications of the QRW on
the hypercube, if they intend to employ mixing properties, need to consider
both the walk dynamics and the precise decoherence model.


title: Asymptotically hyperbolic manifolds with polyhomogeneous metric

abstract:
  We analyze the resolvent and define the scattering matrix for asymptotically
hyperbolic manifolds with metrics which have a polyhomogeneous expansion near
the boundary, and also prove that there is always an essential singularity of
the resolvent in this setting. We use this analysis to prove an inverse result
for conformally compact odd dimensional Einstein manifolds.


title: Scattering of slow-light gap solitons with charges in a two-level medium

abstract:
  The Maxwell-Bloch system describes a quantum two-level medium interacting
with a classical electromagnetic field by mediation of the the population
density. This population density variation is a purely quantum effect which is
actually at the very origin of nonlinearity. The resulting nonlinear coupling
possesses particularly interesting consequences at the resonance (when the
frequency of the excitation is close to the transition frequency of the
two-level medium) as e.g. slow-light gap solitons that result from the
nonlinear instability of the evanescent wave at the boundary. As nonlinearity
couples the different polarizations of the electromagnetic field, the
slow-light gap soliton is shown to experience effective scattering whith
charges in the medium, allowing it for instance to be trapped or reflected.
This scattering process is understood qualitatively as being governed by a
nonlinear Schroedinger model in an external potential related to the charges
(the electrostatic permanent background component of the field).


title:
Band structure of (Sr3Sc2O5)Fe2As2 as a possible parent phase for new
  FeAs superconductors

abstract:
  By means of first-principles FLAPW-GGA calculations, we have investigated the
electronic properties of the newly synthesized layered phase -
(Sr3Sc2O5)Fe2As2. The electronic bands, density of states and Fermi surface
have been evaluated. The resembling of our data for (Sr3Sc2O5)Fe2As2 with band
structure pictures of known FeAs superconducting materials may be considered as
the theoretical background specifying the possibility for (Sr3Sc2O5)Fe2As2 to
become a parent phase for new FeAs superconductors.


title: Conservation laws of the Haldane-Shastry type spin chains

abstract:
  A systematic method to construct the complete set of conserved quantities of
the Haldane-Shastry type spin chains is proposed. The hidden relationship
between the Yang-Baxter relation and the conservation laws of the long-range
interacting integrable models is exposed explicitly. An integrable anisotropic
Haldane-Shastry model is also constructed.


title: Generalized second law of thermodynamics in warped DGP braneworld

abstract:
  We investigate the validity of the generalized second law of thermodynamics
on the $(n-1)$-dimensional brane embedded in the $(n+1)$-dimensional bulk. We
examine the evolution of the apparent horizon entropy extracted through
relation between gravitational equation and the first law of thermodynamics
together with the matter field entropy inside the apparent horizon. We find
that the apparent horizon entropy extracted through connection between gravity
and the first law of thermodynamics satisfies the generalized second law of
thermodynamics. This result holds regardless of whether there is the intrinsic
curvature term on the brane or a cosmological constant in the bulk. The
observed satisfaction of the generalized second law provides further support on
the thermodynamical interpretation of gravity based on the profound connection
between gravity and thermodynamics.


title: Generalized second law of thermodynamics in Gauss-Bonnet braneworld

abstract:
  We investigate the validity the generalized second law of thermodynamics in a
general braneworld model with curvature correction terms on the brane and in
the bulk, respectively. Employing the derived entropy expression associated
with the apparent horizon, we examine the time evolution of the total entropy,
including the derived entropy of the apparent horizon and the entropy of the
matter fields inside the apparent horizon. We show that the generalized second
law of thermodynamics is fulfilled on the 3-brane embedded in the 5D spacetime
with curvature corrections.


title:
Primordial Nucleosynthesis: an updated comparison of observational light
  nuclei abundances with theoretical predictions

abstract:
  An up to date review of Standard Big Bang Nucleosynthesis predictions vs the
astrophysical estimates of light nuclei abundances is here presented. In
particular the analysis reports the expected ranges for baryon fraction and
effective number of neutrinos as obtained by BBN only.


title:
On the nature of faint Low Surface Brightness galaxies in the Coma
  cluster

abstract:
  This project is the continuation of our study of faint Low Surface Brightness
Galaxies (fLSBs) in one of the densest nearby galaxy regions known, the Coma
cluster. Our goal is to improve our understanding of the nature of these
objects by comparing the broad band spectral energy distribution with
population synthesis models. The data were obtained with the MEGACAM and CFH12K
cameras at the CFHT. We used the resulting photometry in 5 broad band filters
(u*, B, V, R, and I), that included new u*-band data, to fit spectral models.
With these spectral fits we inferred a cluster membership criterium, as well as
the ages, dust extinctions, and photometric types of these fLSBs. We show that
about half of the Coma cluster fLSBs have a spectral energy distribution well
represented in our template library while the other half present a flux deficit
at ultraviolet wavelengths. Among the well represented, ~80% are probably part
of the Coma cluster based on their spectral energy distribution. They are
relatively young (younger than 2.3 Gyrs for 90% of the sample) non-starburst
objects. The later their type, the younger fLSBs are. A significant part of the
fLSBs are quite dusty objects. fLSBs are low stellar mass objects (the later
their type the less massive they are), with stellar masses comparable to
globular clusters for the faintest ones. Their characteristics are correlated
with infall directions, confirming the disruptive origin for part of them.


title: Strength and Weakness in Grover's Quantum Search Algorithm

abstract:
  Grover's quantum search algorithm is considered as one of the milestone in
the field of quantum computing. The algorithm can search for a single match in
a database with $N$ records in $O(\sqrt{N})$ assuming that the item must exist
in the database with quadratic speedup over the best known classical algorithm.
This review paper discusses the performance of Grover's algorithm in case of
multiple matches where the problem is expected to be easier. Unfortunately, we
will find that the algorithm will fail for $M>3N/4$, where $M$ is the number of
matches in the list.


title: Autocatalytic reaction-diffusion processes in restricted geometries

abstract:
  We study the dynamics of a system made up of particles of two different
species undergoing irreversible quadratic autocatalytic reactions: $A + B \to
2A$. We especially focus on the reaction velocity and on the average time at
which the system achieves its inert state. By means of both analytical and
numerical methods, we are also able to highlight the role of topology in the
temporal evolution of the system.


title:
Wide spread spectrum watermarking with side information and interference
  cancellation

abstract:
  Nowadays, a popular method used for additive watermarking is wide spread
spectrum. It consists in adding a spread signal into the host document. This
signal is obtained by the sum of a set of carrier vectors, which are modulated
by the bits to be embedded. To extract these embedded bits, weighted
correlations between the watermarked document and the carriers are computed.
Unfortunately, even without any attack, the obtained set of bits can be
corrupted due to the interference with the host signal (host interference) and
also due to the interference with the others carriers (inter-symbols
interference (ISI) due to the non-orthogonality of the carriers). Some recent
watermarking algorithms deal with host interference using side informed
methods, but inter-symbols interference problem is still open. In this paper,
we deal with interference cancellation methods, and we propose to consider ISI
as side information and to integrate it into the host signal. This leads to a
great improvement of extraction performance in term of signal-to-noise ratio
and/or watermark robustness.


title:
Graviton, ghost and instanton condensation on horizon scale of the
  Universe. Dark energy as a macroscopic effect of quantum gravity

abstract:
  We show that cosmological acceleration, Dark Energy (DE) effect is a
consequence of the zero rest mass, conformal non-invariance of gravitons, and
1-loop finiteness of quantum gravity (QG). The effect is due to graviton-ghost
condensates arising from the interference of quantum coherent states. The
theory is constructed as follows: Faddeev-Popov-De Witt gauged path integral ->
factorization of classical and quantum variables -> transition to the 1-loop
approximation -> choice of ghost sector, satisfying 1-loop finiteness of the
theory off the mass shell. The Bogolyubov-Born-Green-Kirckwood-Yvon (BBGKY)
chain for the spectral function of gravitons renormalized by ghosts is used to
build a theory of gravitons in the isotropic Universe. We found three exact
solutions of the equations that describe virtual graviton and ghost condensates
as well as condensates of instanton fluctuations. Exact solutions correspond to
various condensates with different graviton-ghost compositions. The formalism
of the BBGKY chain takes into account the contribution of non-relativistic
matter in the formation of a common self-consistent gravitational field. It is
shown that the era of non-relativistic matter dominance must be replaced by an
era of dominance of graviton-ghost condensate. Pre-asymptotic state of DE is a
condensate of virtual gravitons and ghosts with a constant conformal
wavelength. The asymptotic state predicted by the theory is a graviton-ghost
condensate of constant physical wavelength in the De Sitter space. Such DE
phenomenon is presented in the form of the model that interpolates the exact
solutions of equations of 1-loop QG. Processing of observational DE data
extracted from the Hubble diagram for supernovae SNIa suggests that the
graviton-ghost condensate is an adequate variable component of DE.


title: Second order Poincar\'e inequalities and CLTs on Wiener space

abstract:
  We prove infinite-dimensional second order Poincar\'e inequalities on Wiener
space, thus closing a circle of ideas linking limit theorems for functionals of
Gaussian fields, Stein's method and Malliavin calculus. We provide two
applications: (i) to a new "second order" characterization of CLTs on a fixed
Wiener chaos, and (ii) to linear functionals of Gaussian-subordinated fields.


title:
Large Deviations estimates for some non-local equations I. Fast decaying
  kernels and explicit bounds

abstract:
  We study large deviations for some non-local parabolic type equations. We
show that, under some assumptions on the non-local term, problems defined in a
bounded domain converge with an exponential rate to the solution of the problem
defined in the whole space. We compute this rate in different examples, with
different kernels defining the non-local term, and it turns out that the
estimate of convergence depends strongly on the decay at infinity of that
kernel.


title: Bayesian analysis of the backreaction models

abstract:
  We present the Bayesian analysis of four different types of backreation
models, which are based on the Buchert equations. In this approach, one
considers a solution to the Einstein equations for a general matter
distribution and then an average of various observable quantities is taken.
Such an approach became of considerable interest when it was shown that it
could lead to agreement with observations without resorting to dark energy. In
this paper we compare the LambdaCDM model and the backreation models with SNIa,
BAO, and CMB data, and find that the former is favoured. However, the tested
models were based on some particular assumptions about the relation between the
average spatial curvature and the backreaction, as well as the relation between
the curvature and curvature index. In this paper we modified the latter
assumption, leaving the former unchanged. We find that, by varying the relation
between the curvature and curvature index, we can obtain a better fit.
Therefore, some further work is still needed -- in particular the relation
between the backreaction and the curvature should be revisited in order to
fully determine the feasibility of the backreaction models to mimic dark
energy.


title: Spectral parameter power series for Sturm-Liouville problems

abstract:
  We consider a recently discovered representation for the general solution of
the Sturm-Liouville equation as a spectral parameter power series (SPPS). The
coefficients of the power series are given in terms of a particular solution of
the Sturm-Liouville equation with the zero spectral parameter. We show that,
among other possible applications, this provides a new and efficient numerical
method for solving initial value and boundary value problems. Moreover, due to
its convenient form the representation lends itself to numerical solution of
spectral Sturm-Liouville problems, effectively by calculation of the roots of a
polynomial. We discuss examples of the numerical implementation of the SPPS
method and show it to be equally applicable to a wide class of singular
Sturm-Liouville problems as well as to problems with spectral parameter
dependent boundary conditions.


title:
Automatic Generation of the Axial Lines of Urban Environments to Capture
  What We Perceive

abstract:
  Based on the concepts of isovists and medial axes, we developed a set of
algorithms that can automatically generate axial lines for representing
individual linearly stretched parts of open space of an urban environment. Open
space is the space between buildings, where people can freely move around. The
generation of the axial lines has been a key aspect of space syntax research,
conventionally relying on hand-drawn axial lines of an urban environment, often
called axial map, for urban morphological analysis. Although various attempts
have been made towards an automatic solution, few of them can produce the axial
map that consists of the least number of longest visibility lines, and none of
them really works for different urban environments. Our algorithms provide a
better solution than existing ones. Throughout this paper, we have also argued
and demonstrated that the axial lines constitute a true skeleton, superior to
medial axes, in capturing what we perceive about the urban environment.
  Keywords: Visibility, space syntax, topological analysis, medial axes, axial
lines, isovists


title: A correlation between spin parameter and dark matter halo mass

abstract:
  Using a set of high-resolution dark matter only cosmological simulations we
found a correlation between the dark matter halo mass M and its spin parameter
lambda for objects forming at redshifts z > 10: the spin parameter decreases
with increasing mass. However, halos forming at later times do not exhibit such
a strong correlation, in agreement with the findings of previous studies. While
we presented such a correlation in a previous study using the Bullock et al.
(2001) spin parameter defintion we now defer to the classical definition
showing that the results are independent of the definition.


title:
Anisotropic magnetoresistance in ferromagnetic atomic-sized metal
  contacts

abstract:
  Recent experiments in ferromagnetic atomic-sized contacts have shown that the
anisotropic magnetoresistance (AMR) is greatly enhanced and has an asymmetric
angular dependence as compared with that of bulk samples. The origin of these
effects is still under debate. In this work we present a theoretical analysis
of the AMR in atomic contacts of the 3d ferromagnetic materials. Our results
strongly suggest that the anomalous AMR stems from the reduced symmetry of the
atomic contact geometries. We also present calculations supporting the idea
that the pronounced voltage- and temperature dependence in some experiments can
be attributed to impurities near the constrictions.


title:
Synchrotron Radiation from the Galactic Center in Decaying Dark Matter
  Scenario

abstract:
  We discuss the synchrotron radiation flux from the Galactic center in
unstable dark matter scenario. Motivated by the anomalous excess of the
positron fraction recently reported by the PAMELA collaboration, we consider
the case that the dark matter particle is unstable (and long-lived), and that
energetic electron and positron are produced by the decay of dark matter. Then,
the emitted electron and positron becomes the source of the synchrotron
radiation. We calculate the synchrotron radiation flux for models of decaying
dark matter, which can explain the PAMELA positron excess. Taking the lifetime
of the dark matter of O(10^26 sec), which is the suggested value to explain the
PAMELA anomaly, the synchrotron radiation flux is found to be O(1 kJy/str) or
smaller, depending on the particle-physics and cosmological parameters.


title:
Angular correlations in the cosmic gamma-ray background from dark matter
  annihilation around intermediate-mass black holes

abstract:
  Dark matter (DM) annihilation could in principle contribute to the diffuse
cosmic gamma-ray back- ground (CGB). While with standard assumptions for
cosmological and particle physics parameters this contribution is expected to
be rather small, a number of processes could boost it, including a
larger-than-expected DM annihilation cross-section, or the occurance of DM
substructures such as DM mini-spikes around intermediate-mass black holes. We
show that angular correlations of the CGB provide a tool to disentangle the
signal induced by DM annihilation in mini-spikes from a conventional
astrophysical component. Treating blazars as a known background, we study the
prospects for detecting DM annihilations with the Fermi Gamma-Ray Space
Telescope for different choices of DM mass and annihilation channels.


title: Density of states governs light scattering in photonic crystals

abstract:
  We describe a smooth transition from (fully ordered) photonic crystal to
(fully disordered) photonic glass that enables us to make an accurate
measurement of the scattering mean free path in nanostructured media and, in
turn, establishes the dominant role of the density of states. We have found one
order of magnitude chromatic variation in the scattering mean free path in
photonic crystals for just $\sim 3%$ shift around the band-gap ($\sim 27$ nm in
wavelength).


title: Averaging Robertson-Walker Cosmologies

abstract:
  The cosmological backreaction arises when one directly averages the Einstein
equations to recover an effective Robertson-Walker cosmology, rather than
assuming a background a priori. While usually discussed in the context of dark
energy, strictly speaking any cosmological model should be recovered from such
a procedure. We apply the Buchert averaging formalism to linear
Robertson-Walker universes containing matter, radiation and dark energy and
evaluate numerically the discrepancies between the assumed and the averaged
behaviour, finding the largest deviations for an Einstein-de Sitter universe,
increasing rapidly with Hubble rate to a 0.01% effect for h=0.701. For the LCDM
concordance model, the backreaction is of the order of Omega_eff~4x10^-6, with
those for dark energy models being within a factor of two or three. The impacts
at recombination are of the order of 10^-8 and those in deep radiation
domination asymptote to a constant value. While the effective equations of
state of the backreactions in Einstein-de Sitter, concordance and quintessence
models are generally dust-like, a backreaction with an equation of state
w_eff<-1/3 can be found for strongly phantom models.


title: Topological Interpretation of Barbero-Immirzi Parameter

abstract:
  We set up a canonical Hamiltonian formulation for a theory of gravity based
on a Lagrangian density made up of the Hilbert-Palatini term and, instead of
the Holst term, the Nieh-Yan topological density. The resulting set of
constraints in the time gauge are shown to lead to a theory in terms of a real
SU(2) connection which is exactly the same as that of Barbero and Immirzi with
the coefficient of the Nieh-Yan term identified as the inverse of
Barbero-Immirzi parameter. This provides a topological interpretation for this
parameter. Matter coupling can then be introduced in the usual manner, {\em
without} changing the universal topological Nieh-Yan term.


title: Homomorphism Preservation on Quasi-Wide Classes

abstract:
  A class of structures is said to have the homomorphism-preservation property
just in case every first-order formula that is preserved by homomorphisms on
this class is equivalent to an existential-positive formula. It is known by a
result of Rossman that the class of finite structures has this property and by
previous work of Atserias et al. that various of its subclasses do. We extend
the latter results by introducing the notion of a quasi-wide class and showing
that any quasi-wide class that is closed under taking substructures and
disjoint unions has the homomorphism-preservation property. We show, in
particular, that classes of structures of bounded expansion and that locally
exclude minors are quasi-wide. We also construct an example of a class of
finite structures which is closed under substructures and disjoint unions but
does not admit the homomorphism-preservation property.


title: Is the Luttinger liquid a new state of matter?

abstract:
  We are demonstrating that the Luttinger model with short range interaction
can be treated as a type of Fermi liquid. In line with the main dogma of
Landau's theory one can define a fermion excitation renormalized by interaction
and show that in terms of these fermions any excited state of the system is
described by free particles. The fermions are a mixture of renormalized right
and left electrons. The electric charge and chirality of the Landau
quasi-particle is discussed.


title:
O(a^2) corrections to the propagator and bilinears of Wilson / clover
  fermions

abstract:
  We present the corrections to the fermion propagator, to second order in the
lattice spacing, O(a^2), in 1-loop perturbation theory. The fermions are
described by the clover action and for the gluons we use a 3-parameter family
of Symanzik improved actions. Our calculation has been carried out in a general
covariant gauge. The results are provided as a polynomial of the clover
parameter, and are tabulated for 10 popular sets of the Symanzik coefficients
(Plaquette, Tree-level Symanzik, Iwasaki, TILW and DBW2 action).
  We also study the O(a^2) corrections to matrix elements of fermion bilinear
operators that have the form $\bar\Psi\Gamma\Psi$, where $\Gamma$ denotes all
possible distinct products of Dirac matrices. These correction terms are
essential ingredients for improving, to O(a^2), the matrix elements of the
fermion operators.
  Our results are applicable also to the case of twisted mass fermions.
  A longer write-up of this work, including non-perturbative results, is in
preparation together with V. Gimenez, V. Lubicz and D. Palao.


title:
A note on the convergence of parametrised non-resonant invariant
  manifolds

abstract:
  Truncated Taylor series representations of invariant manifolds are abundant
in numerical computations. We present an aposteriori method to compute the
convergence radii and error estimates of analytic parametrisations of
non-resonant local invariant manifolds of a saddle of an analytic vector field,
from such a truncated series. This enables us to obtain local enclosures, as
well as existence results, for the invariant manifolds.


title: Two-Dimensional Dilaton Gravity and Toda - Liouville Integrable Models

abstract:
  General properties of a class of two-dimensional dilaton gravity (DG)
theories with multi-exponential potentials are studied and a subclass of these
theories, in which the equations of motion reduce to Toda and Liouville
equations, is treated in detail. A combination of parameters of the equations
should satisfy a certain constraint that is identified and solved for the
general multi-exponential model. From the constraint it follows that in DG
theories the integrable Toda equations, generally, cannot appear without
accompanying Liouville equations.
  We also show how the wave-like solutions of the general Toda-Liouville
systems can be simply derived. In the dilaton gravity theory, these solutions
describe nonlinear waves coupled to gravity as well as static states and
cosmologies. A special attention is paid to making the analytic structure of
the solutions of the Toda equations as simple and transparent as possible, with
the aim to gain a better understanding of realistic theories reduced to
dimensions 1+1 and 1+0 or 0+1.


title: Kummer function and High energy String Scatterings

abstract:
  Based on a summation algorithm for Stirling number identity developed
recently, we discover that the ratios calculated previously among high energy
string scattering amplitudes in the Gross regime (GR) can be extracted from the
Kummer function of the second kind. This function naturally shows up in the
leading order of high energy string scattering amplitudes in the Regge regime
(RR). As a result, the identity suggested by string theory calculation can be
rigorously proved by a totally different but sophisticated mathematical method.
We conjecture and give evidences that the existence of these ratios in the RR
persists to all orders in the Regge expansion of high energy string scattering
amplitudes.


title: Compact gauge K vortices

abstract:
  We investigate a version of the abelian Higgs model with a non-standard
kinetic term (K field theory) in 2+1 dimensions. The existence of vortex type
solutions with compact support (topological compactons) is established by a
combination of analytical and numerical methods. This result demonstrates that
the concept of compact solitons in K field theories can be extended to higher
dimensions.


title: Gaugino mass in AdS space

abstract:
  We study supersymmetric QED in AdS4 with massless matter. At 1-loop the
ultra-violet regulator of the theory generates a contribution to the gaugino
mass that is naively inconsistent with unbroken supersymmetry. We show that
this effect, known in flat space as anomaly mediated supersymmetry breaking, is
required to cancel an infra-red contribution arising from the boundary
conditions in AdS space, which necessarily break chiral symmetry. We also
discuss an analogous UV/IR cancellation that is independent of supersymmetry.


title:
Probing the excitation spectrum of nonresonantly pumped polariton
  condensates

abstract:
  We propose a four wave mixing experiment to probe the elementary excitation
spectrum of a non-equilibrium Bose-Einstein condensate of exciton-polaritons
under non-resonant pumping. Analytical calculations based on mean-field theory
show that this method is able to reveal the characteristic negative energy
feature of the Bogoliubov dispersion. Numerical simulations including the
finite spatial profile of the excitation laser spot and a weak disorder confirm
the practical utility of the method for realistic condensates.


title: Support varieties and the Hochschild cohomology ring modulo nilpotence

abstract:
  This is a survey paper based on my talks at the 41st Symposium on Ring Theory
and Representation Theory, held in Shizuoka University, Japan in September
2008, and will appear in the conference proceedings.
  The paper begins with a brief introduction to the use of Hochschild
cohomology in developing the theory of support varieties for a module over an
artin algebra, by Snashall and Solberg (Proc. London Math. Soc.(3) 88 (2004),
705-732). The paper then describes the current status of research concerning
the structure of the Hochschild cohomology ring modulo nilpotence.


title: The 2D Ising model near criticality: a FK percolation analysis

abstract:
  We study the 2d-Ising model defined on finite boxes at temperatures that are
below but very close from the critical point. When the temperature approaches
the critical point and the size of the box grows fast enough, we establish
large deviations estimates on FK-percolation events that concern the phenomenon
of phase coexistence.


title: Electronic properties of LaOFFeAs in the normal state probed by NMR/NQR

abstract:
  We report 139La, 57Fe and 75As nuclear magnetic resonance (NMR) and nuclear
quadrupole resonance (NQR) measurements on powders of the new LaO1-xFxFeAs
superconductor for x = 0 and x = 0.1 at temperatures up to 480 K, and compare
our measured NQR spectra with local density approximation (LDA) calculations.
For all three nuclei in the x = 0.1 material, it is found that the local Knight
shift increases monotonically with an increase in temperature, and scales with
the macroscopic susceptibility, suggesting a single magnetic degree of freedom.
Surprisingly, the spin lattice relaxation rates for all nuclei also scale with
one another, despite the fact that the form factors for each site sample
different regions of q-space. This result suggests a lack of any q-space
structure in the dynamical spin susceptibility that might be expected in the
presence of antiferromagnetic correlations. Rather, our results are more
compatible with simple quasi-particle scattering. Furthermore, we find that the
increase in the electric field gradient at the As cannot be accounted for by
LDA calculations, suggesting that structural changes, in particular the
position of the As in the unit cell, dominate the NQR response.


title: Symmetric lens with extended depth of focus

abstract:
  The lens surface profile is derived based on the instantaneous focal length
versus the lens radius data. The lens design based on instantaneous focal
length versus the lens radius data has many useful applications in software
assisted image focusing technology.


title:
Sigma pole position and errors of a once and twice subtracted dispersive
  analysis of pi-pi scattering data

abstract:
  We show how the new precise data on kaon decays together with forward
dispersion relations, sum rules and once- and twice-subtracted
  Roy's equations allow for a precise determination of the sigma meson pole
position. We present a comparison and a study of the different sources of
uncertainties when using either once- or twice-subtracted Roy's equations to
analyze the data. Finally we present a preliminary determination of the sigma
pole from the constrained dispersive data analysis.


title:
Analytical results for bond percolation and k-core sizes on clustered
  networks

abstract:
  An analytical approach to calculating bond percolation thresholds, sizes of
$k$-cores, and sizes of giant connected components on structured random
networks with non-zero clustering is presented. The networks are generated
using a generalization of Trapman's [P. Trapman, Theor. Pop. Biol. {\bf 71},
160 (2007)] model of cliques embedded in tree-like random graphs. The resulting
networks have arbitrary degree distributions and tunable degree-dependent
clustering. The effect of clustering on the bond percolation thresholds for
networks of this type is examined and contrasted with some recent results in
the literature. For very high levels of clustering the percolation threshold in
these generalized Trapman networks is increased above the value it takes in a
randomly-wired (unclustered) network of the same degree distribution. In
assortative scale-free networks, where the variance of the degree distribution
is infinite, this clustering effect can lead to a non-zero percolation
(epidemic) threshold.


title: Hydrodynamics of the CFL superfluid

abstract:
  At asymptotic high density and low temperature quarks form Cooper pairs in a
color-flavor locked (CFL) configuration. The diquark condensates break
spontaneously the baryon symmetry, and this fact makes the CFL phase also
superfluid. At low temperatures the transport properties are dominated by the
contribution of the superfluid phonon, the Goldstone boson associated to baryon
symmetry breaking, in full analogy to what happens in superfluid He4. We
discuss how to derive transport properties in the ultracold regime making use
of an analogue model of gravity. We also review how this model can be used to
study the scattering of phonons with quantized vortices in a rotating system.
Finally, we consider the implications of these results in studying the
rotational properties of compact stars made of CFL quark matter


title:
Continuity of the integrated density of states on random length metric
  graphs

abstract:
  We establish several properties of the integrated density of states for
random quantum graphs: Under appropriate ergodicity and amenability
assumptions, the integrated density of states can be defined using an
exhaustion procedure by compact subgraphs. A trace per unit volume formula
holds, similarly as in the Euclidean case. Our setting includes periodic
graphs. For a model where the edge length are random and vary independently in
a smooth way we prove a Wegner estimate and related regularity results for the
integrated density of states. These results are illustrated for an example
based on the Kagome lattice. In the periodic case we characterise all compactly
supported eigenfunctions and calculate the position and size of discontinuities
of the integrated density of states.


title:
Localized Modes of the Linear Periodic Schr\"{o}dinger Operator with a
  Nonlocal Perturbation

abstract:
  We consider the existence of localized modes corresponding to eigenvalues of
the periodic Schr\"{o}dinger operator $-\partial_x^2+ V(x)$ with an interface.
The interface is modeled by a jump either in the value or the derivative of
$V(x)$ and, in general, does not correspond to a localized perturbation of the
perfectly periodic operator. The periodic potentials on each side of the
interface can, moreover, be different. As we show, eigenvalues can only occur
in spectral gaps. We pose the eigenvalue problem as a $C^1$ gluing problem for
the fundamental solutions (Bloch functions) of the second order ODEs on each
side of the interface. The problem is thus reduced to finding matchings of the
ratio functions $R_\pm=\frac{\psi_\pm'(0)}{\psi_\pm(0)}$, where $\psi_\pm$ are
those Bloch functions that decay on the respective half-lines. These ratio
functions are analyzed with the help of the Pr\"{u}fer transformation. The
limit values of $R_\pm$ at band edges depend on the ordering of Dirichlet and
Neumann eigenvalues at gap edges. We show that the ordering can be determined
in the first two gaps via variational analysis for potentials satisfying
certain monotonicity conditions. Numerical computations of interface
eigenvalues are presented to corroborate the analysis.


title:
Phases and collective modes of hardcore Bose-Fermi mixture in an optical
  lattice

abstract:
  We obtain the phase diagram of a Bose-Fermi mixture of hardcore spinless
Bosons and spin-polarized Fermions with nearest neighbor intra-species
interaction and on-site inter-species repulsion in an optical lattice at
half-filling using a slave-boson mean-field theory. We show that such a system
can have four possible phases which are a) supersolid Bosons coexisting with
Fermions in the Mott state, b) Mott state of Bosons coexisting with Fermions in
a metallic or charge-density wave state, c) a metallic Fermionic state
coexisting with superfluid phase of Bosons, and d) Mott insulating state of
Fermions and Bosons. We chart out the phase diagram of the system and provide
analytical expressions for the phase boundaries within mean-field theory. We
demonstrate that the transition between these phases are generically first
order with the exception of that between the supersolid and the Mott states
which is a continuous quantum phase transition. We also obtain the low-energy
collective excitations of the system in these phases. Finally, we study the
particle-hole excitations in the Mott insulating phase and use it to determine
the dynamical critical exponent $z$ for the supersolid-Mott insulator
transition. We discuss experiments which can test our theory.


title: Formation of eta-mesic nuclei by (pi,N) reaction and N^*(1535) in medium

abstract:
  We calculate formation spectra of eta-nucleus systems in (pi,N) reactions
with nuclear targets, which can be performed at existing and/or forthcoming
facilities, including J-PARC, in order to investigate eta-nucleus interactions.
Based on the N^*(1535) dominance in the eta N system, eta-mesic nuclei are
suitable systems for study of in-medium properties of the N^*(1535) baryon
resonance, such as reduction of the mass difference of N and N^* in nuclear
medium, which affects level structure of the eta and N^*-hole modes. We find
that clear information on the in-medium N^*- and eta-nucleus interactions can
be obtained through the formation spectra of the eta-mesic nuclei. We also
discuss the experimental feasibilities by showing several spectra of (pi,N)
reactions calculated with possible experimental settings. Coincident
measurements of pi N pairs from the N^* decays in nuclei help us to reduce
backgrounds.


title:
Towards surface quantum optics with Bose-Einstein condensates in
  evanescent waves

abstract:
  We present a surface trap which allows for studying the coherent interaction
of ultracold atoms with evanescent waves. The trap combines a magnetic Joffe
trap with a repulsive evanescent dipole potential. The position of the magnetic
trap can be controlled with high precision which makes it possible to move
ultracold atoms to the surface of a glass prism in a controlled way. The
optical potential of the evanescent wave compensates for the strong attractive
van der Waals forces and generates a potential barrier at only a few hundred
nanometers from the surface. The trap is tested with Rb Bose-Einstein
condensates (BEC), which are stably positioned at distances from the surfaces
below one micrometer.


title: On scale-free and poly-scale behaviors of random hierarchical network

abstract:
  In this paper the question about statistical properties of
block--hierarchical random matrices is raised for the first time in connection
with structural characteristics of random hierarchical networks obtained by
mipmapping procedure. In particular, we compute numerically the spectral
density of large random adjacency matrices defined by a hierarchy of the
Bernoulli distributions $\{q_1,q_2,...\}$ on matrix elements, where
$q_{\gamma}$ depends on hierarchy level $\gamma$ as $q_{\gamma}=p^{-\mu
\gamma}$ ($\mu>0$). For the spectral density we clearly see the free--scale
behavior. We show also that for the Gaussian distributions on matrix elements
with zero mean and variances $\sigma_{\gamma}=p^{-\nu \gamma}$, the tail of the
spectral density, $\rho_G(\lambda)$, behaves as $\rho_G(\lambda) \sim
|\lambda|^{-(2-\nu)/(1-\nu)}$ for $|\lambda|\to\infty$ and $0<\nu<1$, while for
$\nu\ge 1$ the power--law behavior is terminated. We also find that the vertex
degree distribution of such hierarchical networks has a poly--scale fractal
behavior extended to a very broad range of scales.


title: Peripheral mixing of passive scalar at small Reynolds number

abstract:
  Mixing of a passive scalar in the peripheral region close to a wall is
investigated by means of accurate direct numerical simulations of both a
three-dimensional Couette channel flow at low Reynolds numbers and a
two-dimensional synthetic flow. In both cases, the resulting phenomenology can
be understood in terms of the theory recently developed by Lebedev and Turitsyn
[Phys. Rev. E 69, 036301, 2004]. Our results prove the robustness of the
identified mechanisms responsible for the persistency of scalar concentration
close to the wall with important consequences in completely different fields
ranging from microfluidic applications to environmental dispersion modeling.


title: Pygmy dipole strength in 90Zr

abstract:
  The dipole response of the N=50 nucleus 90Zr was studied in photon-scattering
experiments at the electron linear accelerator ELBE with bremsstrahlung
produced at kinetic electron energies of 7.9, 9.0, and 13.2 MeV. We identified
189 levels up to an excitation energy of 12.9 MeV. Statistical methods were
applied to estimate intensities of inelastic transitions and to correct the
intensities of the ground-state transitions for their branching ratios. In this
way we derived the photoabsorption cross section up to the neutron-separation
energy. This cross section matches well the photoabsorption cross section
obtained from (gamma,n) data and thus provides information about the extension
of the dipole-strength distribution toward energies below the
neutron-separation energy. An enhancement of E1 strength has been found in the
range of 6 MeV to 11 MeV. Calculations within the framework of the
quasiparticle-phonon model ascribe this strength to a vibration of the
excessive neutrons against the N = Z neutron-proton core, giving rise to a
pygmy dipole resonance.


title: Invariant manifolds and the response of spiral arms in barred galaxies

abstract:
  The unstable invariant manifolds of the short-period family of periodic
orbits around the unstable Lagrangian points $L_1$ and $L_2$ of a barred galaxy
define loci in the configuration space which take the form of a trailing spiral
pattern. In the present paper we investigate this association in the case of
the self-consistent models of Kaufmann & Contopoulos (1996) which provide an
approximation of real barred-spiral galaxies. We also examine the relation of
`response' models of barred-spiral galaxies with the theory of the invariant
manifolds. Our main results are the following: The invariant manifolds yield
the correct form of the imposed spiral pattern provided that their calculation
is done with the spiral potential term turned on. We provide a theoretical
model explaining the form of the invariant manifolds that supports the spiral
structure. The azimuthal displacement of the Lagrangian points with respect to
the bar's major axis is a crucial parameter in this modeling. When this is
taken into account, the manifolds necessarily develop in a spiral-like domain
of the configuration space, delimited from below by the boundary of a
banana-like non-permitted domain, and from above either by rotational KAM tori
or by cantori forming a stickiness zone. We construct `spiral response' models
on the basis of the theory of the invariant manifolds and examine the
connection of the latter to the `response' models (Patsis 2006) used to fit
real barred-spiral galaxies, explaining how are the manifolds related to a
number of morphological features seen in such models.


title: Special L-values of t-motives: a conjecture

abstract:
  We propose a conjecture on special values of $ L $-functions in a function
field context with positive characteristic coefficients.
  For $ M $ a uniformizable $ t $-motive with everywhere good reduction we
conjecture a relation between the value of the Goss $ L $-function $ L(M^\vee,
s) $ at $ s = 0 $ and the uniformization of the abelian $ t $-module associated
with $ M $.
  When $ M $ is a power of the Carlitz $ t $-motive the conjecture specializes
to a theorem of Anderson and Thakur on Carlitz zeta values. Beyond this case we
present numerical evidence.


title: Exceptional Vertex Operator Algebras and the Virasoro Algebra

abstract:
  We consider exceptional vertex operator algebras for which particular Casimir
vectors constructed from the primary vectors of lowest conformal weight are
Virasoro descendants of the vacuum. We discuss constraints on these theories
that follow from an analysis of appropriate genus zero and genus one two point
correlation functions. We find explicit differential equations for the
partition function in the cases where the lowest weight primary vectors form a
Lie algebra or a Griess algebra. Examples include the Wess-Zumino-Witten model
for Deligne's exceptional Lie algebras and the Moonshine Module. We partially
verify the irreducible decomposition of the tensor product of Deligne's
exceptional Lie algebras and consider the possibility of similar decompositions
for tensor products of the Griess algebra. We briefly discuss some conjectured
extremal vertex operator algebras arising in Witten's recent work on three
dimensional black holes.


title: Semi-analytical formulas for the Hertzsprung-Russell Diagram

abstract:
  The absolute visual magnitude as function of the observed colour (B-V), also
named Hertzsprung-Russell diagram can be described through five equations; that
in presence of calibrated stars means eight constants. The developed framework
allows to deduce the remaining physical parameters that are mass, radius and
luminosity. This new technique is applied to the first 10 pc, the first 50 pc,
the Hyades and to the determination of the distance of a cluster. The case of
the white dwarfs is analysed assuming the absence of calibrated data: our
equation produces a smaller $\chi^2$ in respect to the standard
colour-magnitude calibration when applied to the Villanova Catalog of
Spectroscopically Identified White Dwarfs. The theoretical basis of the
formulae for the colours and the bolometric correction of the stars are
clarified through a Taylor expansion in the temperature of the Planck
distribution.


title: Monstrous and Generalized Moonshine and Permutation Orbifolds

abstract:
  We consider the application of permutation orbifold constructions towards a
new possible understanding of the genus zero property in Monstrous and
Generalized Moonshine. We describe a theory of twisted Hecke operators in this
setting and conjecture on the form of Generalized Moonshine replication
formulas.


title: Influence of the photon - neutrino processes on magnetar cooling

abstract:
  The photon-neutrino processes $\gamma e^{\pm} \to e^{\pm} \nu \bar \nu$,
$\gamma \to \nu \bar \nu$ and $\gamma \gamma \to \nu \bar \nu$ are investigated
in the presence of a strongly magnetized and dense electron-positron plasma.
The amplitudes of the reactions $\gamma e^{\pm} \to e^{\pm} \nu \bar \nu$ and
$\gamma \gamma \to \nu \bar \nu$ are obtained. In the case of a cold degenerate
plasma contributions of the considering processes to neutrino emissivity are
calculated. It is shown that contribution of the process $\gamma \gamma \to \nu
\bar \nu$ to neutrino emissivity is supressed in comparision with the
contributions of the processes $\gamma e^{\pm} \to e^{\pm} \nu \bar \nu$ and
$\gamma \to \nu \bar \nu$. The constraint on the magnetic field strength in the
magnetar outer crust is obtained.


title: Representation of entanglement by negative quasi-probabilities

abstract:
  Any bipartite quantum state has quasi-probability representations in terms of
separable states. For entangled states these quasi-probabilities necessarily
exhibit negativities. Based on the general structure of composite quantum
states, one may reconstruct such quasi-propabilities from experimental data.
Because of ambiguity, the quasi-probabilities obtained by the bare
reconstruction are insufficient to identify entanglement. An optimization
procedure is introduced to derive quasi-probabilities with a minimal amount of
negativity. Negativities of optimized quasi-probabilities unambiguously prove
entanglement, their positivity proves separability.


title:
Direct Simulations of Particle Acceleration in Fluctuating
  Electromagnetic Field across a Shock

abstract:
  We simulate the acceleration processes of collisionless particles in a shock
structure with magnetohydrodynamical (MHD) fluctuations. The electromagnetic
field is represented as a sum of MHD shock solution ($\Mag_0, \Ele_0$) and
torsional Alfven modes spectra ($\delta \Mag, \delta \Ele $). We represent
fluctuation modes in logarithmic wavenumber space. Since the electromagnetic
fields are represented analytically, our simulations can easily cover as large
as eight orders of magnitude in resonant frequency, and do not suffer from
spatial limitations of box size or grid spacing. We deterministically calculate
the particle trajectories under the Lorenz force for time interval of up to ten
years, with a time step of $\sim 0.5 \sec$. This is sufficient to resolve
Larmor frequencies without a stochastic treatment. Simulations show that the
efficiency of the first order Fermi acceleration can be parametrized by the
fluctuation amplitude $\eta \equiv < \delta B^2 > ^{\frac 1 2} {B_0}^{-1}$ .
Convergence of the numerical results is shown by increasing the number of wave
modes in Fourier space while fixing $\eta$. Efficiency of the first order Fermi
acceleration has a maximum at $ \eta \simeq 10^1$. The acceleration rate
depends on the angle between the shock normal and $\Mag_0$, and is highest when
the angle is zero. Our method will provide a convenient tool for comparing
collisionless turbulence theories with, for example, observations of bipolar
structure of super nova remnants (SNRs) and shell-like synchrotron-radiating
structure.


title:
On the History of Geometrization of Space-time: From Minkowski to
  Finsler Geometry

abstract:
  The article is a tribute to Hermann Minkowski leading from his geometry of
numbers to an attempt at using Finsler geometry for a break of Lorentz
invariance.


title: Electromagnetic Processes In Strongly Magnetized Plasma

abstract:
  The electromagnetic processes of Compton scattering and photon
splitting/merging are investigated in the presence of strongly magnetized
electron-positron plasma. The influence of these processes on the radiation
transfer in the astrophysical environment is studied. In particular, the
contribution of the processes under consideration in coefficients of the
transfer equation is calculated. We show the importance of photon
splitting/merging contribution and taking into account of photon dispersion and
wave function renormalization in strong magnetic field and plasma.


title:
Interpolative approach for electron-electron and electron-phonon
  interactions: from the Kondo to the polaronic regime

abstract:
  We present a theoretical approach to determine the electronic properties of
nanoscale systems exhibiting strong electron-electron and electron-phonon
interactions and coupled to metallic electrodes. This approach is based on an
interpolative ansatz for the electronic self-energy which becomes exact both in
the limit of weak and strong coupling to the electrodes. The method provides a
generalization of previous interpolative schemes which have been applied to the
purely electronic case extensively. As a test case we consider the single level
Anderson-Holstein model. The results obtained with the interpolative ansatz are
in good agreement with existing data from Numerical Renormalization Group
calculations. We also check our results by considering the case of the
electrodes represented by a few discrete levels which can be diagonalized
exactly. The approximation describes properly the transition from the Kondo
regime where electron-electron interactions dominate to the polaronic case
characterized by a strong electron-phonon interaction.


title: Invariant elliptic curves as attractors in the projective plane

abstract:
  Let f be a rational self-map of P^2 which leaves invariant an elliptic curve
C with strictly negative transverse Lyapunov exponent. We show that C is an
attractor, i.e. it possesses a dense orbit and its basin is of strictly
positive measure.


title: Anomalous binding of Fe atoms in chromium

abstract:
  Binding of 57Fe atoms in a metallic chromium was investigated in a Cr-Fe
alloy, containing less than 0.1 at% Fe enriched to ~95 % in 57Fe isotope, using
57Fe-site Mossbauer spectroscopy. The binding force was derived from the Debye
temperature, T_D, that, in turn, was calculated from the temperature dependence
of the central shift of the Mossbauer spectra recorded in the range of 80 to
330 K. Following a temperature dependence of the line width that shows a
minimum at ~155 K, two temperature intervals were considered: a low temperature
one (LT) ranging from 80 to 155 K, and the T_D - value of 292 (12) K or 279
(34) K, and a high temperature one (HT) ranging from 155 to 330 K with the T_D
- value of 399 (15) or 399 (25) K, depending on the fitting procedure. The
corresponding values of the harmonic force (spring) constant are: 35.4 N/m and
66.1 N/m or 33.8 N/m and 66.1 N/m for the LT and HT, respectively. This means
that in the HT range the binding force of 57Fe atoms by the Cr matrix is by a
factor of ~1.9 - 2 stronger than that in the LT range. This anomaly is possibly
related with a different polarization of the spin-density waves in the LT and
HT "phases".