title: Uncertainties inherent in the decomposition of a Transformation

abstract:
  This contribution adds to the points on the <indeterminacy of special
relativity> made by De Abreu and Guerra. We show that the Lorentz
Transformation can be composed by the physical observations made in a frame K
of events in a frame K-prime viz i) objects in K-prime are moving at a speed v
relative to K, ii) distances and time intervals measured by K-prime are at
variance with those measured by K and iii) the concept of simultaneity is
different in K-prime compared to K. The order in which the composition is
executed determines the nature of the middle aspect (ii). This essential
uncertainty of the theory can be resolved only by a universal synchronicity as
discussed in [1] based on the unique frame in which the one way speed of light
is constant in all directions.


title: More on Combinatorial Batch Codes

abstract:
  Paterson, Stinson and Wei \cite{PSW} introduced Combinatorial batch codes,
which are combinatorial description of Batch code. Batch codes were first
presented by Ishai, Kushilevita, Ostrovsky and Sahai \cite{IKOS} in STOC'04. In
this paper we answer some of the questions put forward by Paterson, Stinson and
Wei and give some results for the general case $t>1$ which were not studied by
the authors.


title: Gravito-magnetic gyroscope precession in Palatini f(R) gravity

abstract:
  We study gravito-magnetic effects in the Palatini formalism of f(R) gravity.
On using the Kerr-de Sitter metric, which is a solution of f(R) field
equations, we calculate the impact of f(R) gravity on the gravito-magnetic
precession of an orbiting gyroscope. We show that, even though an $f(R)$
contribution is present in principle, its magnitude is negligibly small and far
to be detectable in the present (like GP-B) and foreseeable space missions or
observational tests around the Earth.


title:
Quantum Tomographic Reconstruction with Error Bars: a Kalman Filter
  Approach

abstract:
  We present a novel quantum tomographic reconstruction method based on
Bayesian inference via the Kalman filter update equations. The method not only
yields the maximum likelihood/optimal Bayesian reconstruction, but also a
covariance matrix expressing the measurement uncertainties in a complete way.
  From this covariance matrix the error bars on any derived quantity can be
easily calculated. This is a first step towards the broader goal of devising an
omnibus reconstruction method that could be adapted to any tomographic setup
with little effort and that treats measurement uncertainties in a statistically
well-founded way.
  In this first part we restrict ourselves to the important subclass of
tomography based on measurements with discrete outcomes (as opposed to
continuous ones), and we also ignore any measurement imperfections (dark
counts, less than unit detector efficiency, etc.), which will be treated in a
follow-up paper. We illustrate our general theory on real tomography
experiments of quantum optical information processing elements.


title:
Projector-based renormalization method (PRM) and its application to
  many-particle systems

abstract:
  Despite the advances in the development of numerical methods analytical
approaches play a key role on the way towards a deeper understanding of
strongly interacting systems. In this regards, renormalization schemes for
Hamiltonians represent an important new direction in the field. Among these
renormalization schemes the projector-based renormalization method (PRM)
reviewed here might be the approach with the widest range of possible
applications: As demonstrated in this review, continuous unitary
transformations, perturbation theory, non-perturbative phenomena, and
quantum-phase transitions can be understood within the same theoretical
framework. This review starts from the definition of an effective Hamiltonian
by means of projection operators that allows the evaluation within perturbation
theory as well as the formulation of a renormalization scheme. The developed
approach is then applied to three different many-particle systems: At first, we
study the electron-phonon problem to discuss several modifications of the
method and to demonstrate how phase transitions can be described within the
PRM. Secondly, to show that non-perturbative phenomena are accessible by the
PRM, the periodic Anderson model is investigated to describe heavy-fermion
behavior. Finally, we discuss the quantum-phase transition in the
one-dimensional Holstein model of spinless fermions where both metallic and
insulating phase are described within the same theoretical framework.


title: General properties of nonlinear mean field Fokker-Planck equations

abstract:
  Recently, several authors have tried to extend the usual concepts of
thermodynamics and kinetic theory in order to deal with distributions that can
be non-Boltzmannian. For dissipative systems described by the canonical
ensemble, this leads to the notion of nonlinear Fokker-Planck equation (T.D.
Frank, Non Linear Fokker-Planck Equations, Springer, Berlin, 2005). In this
paper, we review general properties of nonlinear mean field Fokker-Planck
equations, consider the passage from the generalized Kramers to the generalized
Smoluchowski equation in the strong friction limit, and provide explicit
examples for Boltzmann, Tsallis and Fermi-Dirac entropies.


title:
Bias driven coherent carrier dynamics in a two-dimensional aperiodic
  potential

abstract:
  We study the dynamics of an electron wave-packet in a two-dimensional square
lattice with an aperiodic site potential in the presence of an external uniform
electric field. The aperiodicity is described by $\epsilon_{\bf m} =
V\cos{(\pi\alpha m_x^{\nu_x})}\cos{(\pi\alpha m_y^{\nu_y})}$ at lattice sites
$(m_x, m_y)$, with $\pi \alpha$ being a rational number, and $\nu_x$ and
$\nu_y$ tunable parameters, controlling the aperiodicity. Using an exact
diagonalization procedure and a finite-size scaling analysis, we show that in
the weakly aperiodic regime ($\nu_x,\nu_y < 1$), a phase of extended states
emerges in the center of the band at zero field giving support to a macroscopic
conductivity in the thermodynamic limit. Turning on the field gives rise to
Bloch oscillations of the electron wave-packet. The spectral density of these
oscillations may display a double peak structure signaling the spatial
anisotropy of the potential landscape. The frequency of the oscillations can be
understood using a semi-classical approach.


title: Lyapunov spectrum for rational maps

abstract:
  We study the dimension spectrum of Lyapunov exponents for rational maps on
the Riemann sphere.


title: A Brief History of Dark Energy

abstract:
  Gurzadyan-Xue Dark Energy was derived in 1986 (twenty years before the paper
of Gurzadyan-Xue). The paper by the present author, titled The Planck Length as
a Cosmological Constant, published in Astrophysics Space Science, Vol. 127,
p.133-137, 1986 contains the formula claimed to have been derived by
Gurzadyan-Xue (in 2003).


title: Algebraic reduction for space-time codes based on quaternion algebras

abstract:
  In this paper we introduce a new right preprocessing method for the decoding
of 2x2 algebraic STBCs, called algebraic reduction, which exploits the
multiplicative structure of the code. The principle of the new reduction is to
absorb part of the channel into the code, by approximating the channel matrix
with an element of the maximal order of the algebra. We prove that algebraic
reduction attains the receive diversity when followed by a simple ZF detection.
Simulation results for the Golden Code show that using MMSE-GDFE left
preprocessing, algebraic reduction with simple ZF detection has a loss of only
$3 \dB$ with respect to ML decoding.


title: The colorful Helly theorem and colorful resolutions of ideals

abstract:
  We demonstrate that the topological Helly theorem and the algebraic
Auslander-Buchsbaum may be viewed as different versions of the same phenomenon.
Using this correspondence we show how the colorful Helly theorem of I.Barany
and its generalizations by G.Kalai and R.Meshulam translates to the algebraic
side. Our main results are algebraic generalizations of these translations,
which in particular gives a syzygetic version of Hellys theorem.


title:
Topological expansion of the Bethe ansatz, and non-commutative algebraic
  geometry

abstract:
  In this article, we define a non-commutative deformation of the "symplectic
invariants" of an algebraic hyperelliptical plane curve. The necessary
condition for our definition to make sense is a Bethe ansatz. The commutative
limit reduces to the symplectic invariants, i.e. algebraic geometry, and thus
we define non-commutative deformations of some algebraic geometry quantities.
In particular our non-commutative Bergmann kernel satisfies a Rauch variational
formula. Those non-commutative invariants are inspired from the large N
expansion of formal non-hermitian matrix models. Thus they are expected to be
related to the enumeration problem of discrete non-orientable surfaces of
arbitrary topologies.


title: Timing the accretion flow around accreting millisecond pulsars

abstract:
  At present, ten years after they were first discovered, ten accreting
millisecond pulsars are known. I present a study of the aperiodic X-ray
variability in three of these systems, which led to the discovery of
simultaneous kHz quasi periodic oscillations in XTE J1807-294 and extremely
strong broadband noise at unusually low variability frequencies in IGR
J00291+5934. Furthermore, we classified SWIFT J1756.9-2508 as an atoll source
and measured in its 2007 outburst spectral and variability properties typical
of the extreme island state. I also give detailed estimates of the total
fluence during the studied outbursts.


title: On phase segregation in nonlocal two-particle Hartree systems

abstract:
  We prove the phase segregation phenomenon to occur in the ground state
solutions of an interacting system of two self-coupled repulsive Hartree
equations for large nonlinear and nonlocal interactions. A self-consistent
numerical investigation visualizes the approach to this segregated regime.


title:
Achievability of the Rate ${1/2}\log(1+\es)$ in the Discrete-Time
  Poisson Channel

abstract:
  A simple lower bound to the capacity of the discrete-time Poisson channel
with average energy $\es$ is derived. The rate ${1/2}\log(1+\es)$ is shown to
be the generalized mutual information of a modified minimum-distance decoder,
when the input follows a gamma distribution of parameter 1/2 and mean $\es$.


title: Phase Response Curves of Coupled Oscillators

abstract:
  Many real oscillators are coupled to other oscillators and the coupling can
affect the response of the oscillators to stimuli. We investigate phase
response curves (PRCs) of coupled oscillators. The PRCs for two weakly coupled
phase-locked oscillators are analytically obtained in terms of the PRC for
uncoupled oscillators and the coupling function of the system. Through
simulation and analytic methods, the PRCs for globally coupled oscillators are
also discussed.


title: Strongly closed subgroups of finite groups

abstract:
  This paper gives a complete classification of the finite groups that contain
a strongly closed p-subgroup for p any prime.


title:
Finding rare objects and building pure samples: Probabilistic quasar
  classification from low resolution Gaia spectra

abstract:
  We develop and demonstrate a probabilistic method for classifying rare
objects in surveys with the particular goal of building very pure samples. It
works by modifying the output probabilities from a classifier so as to
accommodate our expectation (priors) concerning the relative frequencies of
different classes of objects. We demonstrate our method using the Discrete
Source Classifier, a supervised classifier currently based on Support Vector
Machines, which we are developing in preparation for the Gaia data analysis.
DSC classifies objects using their very low resolution optical spectra. We look
in detail at the problem of quasar classification, because identification of a
pure quasar sample is necessary to define the Gaia astrometric reference frame.
By varying a posterior probability threshold in DSC we can trade off sample
completeness and contamination. We show, using our simulated data, that it is
possible to achieve a pure sample of quasars (upper limit on contamination of 1
in 40,000) with a completeness of 65% at magnitudes of G=18.5, and 50% at
G=20.0, even when quasars have a frequency of only 1 in every 2000 objects. The
star sample completeness is simultaneously 99% with a contamination of 0.7%.
Including parallax and proper motion in the classifier barely changes the
results. We further show that not accounting for class priors in the target
population leads to serious misclassifications and poor predictions for sample
completeness and contamination. (Truncated)


title: The growth of matter perturbations in f(R) models

abstract:
  We consider the linear growth of matter perturbations on low redshifts in
some $f(R)$ dark energy (DE) models. We discuss the definition of dark energy
(DE) in these models and show the differences with scalar-tensor DE models. For
the $f(R)$ model recently proposed by Starobinsky we show that the growth
parameter $\gamma_0\equiv \gamma(z=0)$ takes the value $\gamma_0\simeq 0.4$ for
$\Omega_{m,0}=0.32$ and $\gamma_0\simeq 0.43$ for $\Omega_{m,0}=0.23$, allowing
for a clear distinction from $\Lambda$CDM. Though a scale-dependence appears in
the growth of perturbations on higher redshifts, we find no dispersion for
$\gamma(z)$ on low redshifts up to $z\sim 0.3$, $\gamma(z)$ is also
quasi-linear in this interval. At redshift $z=0.5$, the dispersion is still
small with $\Delta \gamma\simeq 0.01$. As for some scalar-tensor models, we
find here too a large value for $\gamma'_0\equiv \frac{d\gamma}{dz}(z=0)$,
$\gamma'_0\simeq -0.25$ for $\Omega_{m,0}=0.32$ and $\gamma'_0\simeq -0.18$ for
$\Omega_{m,0}=0.23$. These values are largely outside the range found for DE
models in General Relativity (GR). This clear signature provides a powerful
constraint on these models.


title: Smile dynamics -- a theory of the implied leverage effect

abstract:
  We study in details the skew of stock option smiles, which is induced by the
so-called leverage effect on the underlying -- i.e. the correlation between
past returns and future square returns. This naturally explains the anomalous
dependence of the skew as a function of maturity of the option. The market cap
dependence of the leverage effect is analyzed using a one-factor model. We show
how this leverage correlation gives rise to a non-trivial smile dynamics, which
turns out to be intermediate between the "sticky strike" and the "sticky delta"
rules. Finally, we compare our result with stock option data, and find that
option markets overestimate the leverage effect by a large factor, in
particular for long dated options.


title: Wormholes supported by phantom-like modified Chaplygin gas

abstract:
  We have examined the possible construction of a stationary, spherically
symmetric and spatially inhomogeneous wormhole spacetime supported by the
phantom energy. The later is supposed to be represented by the modified
Chaplygin gas equation of state. The solutions so obtained satisfy the flare
out and the asymptotic flatness conditions. It is also shown that the averaged
null energy condition has to be violated for the existence of the wormhole.


title: A record-driven growth process

abstract:
  We introduce a novel stochastic growth process, the record-driven growth
process, which originates from the analysis of a class of growing networks in a
universal limiting regime. Nodes are added one by one to a network, each node
possessing a quality. The new incoming node connects to the preexisting node
with best quality, that is, with record value for the quality. The emergent
structure is that of a growing network, where groups are formed around record
nodes (nodes endowed with the best intrinsic qualities). Special emphasis is
put on the statistics of leaders (nodes whose degrees are the largest). The
asymptotic probability for a node to be a leader is equal to the Golomb-Dickman
constant omega=0.624329... which arises in problems of combinatorical nature.
This outcome solves the problem of the determination of the record breaking
rate for the sequence of correlated inter-record intervals. The process
exhibits temporal self-similarity in the late-time regime. Connections with the
statistics of the cycles of random permutations, the statistical properties of
randomly broken intervals, and the Kesten variable are given.


title: The equivariant K-theory of toric varieties

abstract:
  This paper contains two results concerning the equivariant K-theory of toric
varieties. The first is a formula for the equivariant K-groups of an arbitrary
affine toric variety, generalizing the known formula for smooth ones. In fact,
this result is established in a more general context, involving the K-theory of
graded projective modules. The second result is a new proof of a theorem due to
Vezzosi and Vistoli concerning the equivariant K-theory of smooth (not
necessarily affine) toric varieties.


title:
Sample Size Effects on the Transport Characteristics of Mesoscopic
  Graphite Samples

abstract:
  In this work we investigated correlations between the internal microstructure
and sample size (lateral as well as thickness) of mesoscopic, tens of nanometer
thick graphite (multigraphene) samples and the temperature $(T)$ and field
$(B)$ dependence of their electrical resistivity $\rho(T,B)$. Low energy
transmission electron microscopy reveals that the original highly oriented
pyrolytic graphite material -- from which the multigraphene samples were
obtained by exfoliation -- is composed of a stack of $\sim 50 $nm thick and
micrometer long crystalline regions separated by interfaces running parallel to
the graphene planes. We found a qualitative and quantitative change in the
behavior of $\rho(T,B)$ upon thickness of the multigraphene samples, indicating
that their internal microstructure is important.} {The overall results indicate
that the metallic-like behavior of $\rho(T)$ at zero field measured for bulk
graphite samples is not intrinsic of ideal graphite. The results suggest that
the interfaces between crystalline regions may be responsible for the
superconducting-like properties observed in graphite. Our transport
measurements also show that reducing the sample lateral size as well as the
length between voltage electrodes decreases the magnetoresistance, in agreement
with recently published results. The magnetoresistance of the multigraphene
samples shows a scaling of the form ($(R(B) - R(0))/R(0))/T^\alpha = f(B/T)$
with a sample dependent exponent $\alpha \sim 1$, which applies in the whole
temperature 2 K $\le T \le 270$K and magnetic field range $B \le 8 $T.


title: The Lagoon Nebula and its Vicinity

abstract:
  The Lagoon Nebula is an HII region in the Sagittarius Arm, about 1.3 kpc
away, associated with the young (1-3 Myr) open cluster NGC 6530, which contains
several O stars and several dozen B stars. Lower-mass cluster members, detected
by X-ray and H-alpha emission, and by near-IR excess, number more than a
thousand. Myr-old star formation is traced by the optically-visible HII region
and cluster; observations of infrared and submillimetre-wave emission, and of
optical emission features, indicate ongoing star formation in several locations
across the Lagoon. The most prominent of these are the Hourglass Nebula and
M8E. Submillimetre-wave observations also reveal many clumps of dense molecular
gas, which may form the next generation of stars. The complex structure of the
region has been shaped by the interaction of the underlying molecular gas with
multiple massive stars and episodes of star formation. NGC 6530 is the oldest
component, with the newest stars found embedded in the molecular gas behind the
cluster and at its southern rim. A degree to the east of the Lagoon, Simeis 188
is a complex of emission and reflection nebulae, including the bright-rimmed
cloud NGC 6559; the presence of H-alpha emission stars suggests ongoing star
formation.


title: Periodic Pattern in the Residual-Velocity Field of OB Associations

abstract:
  An analysis of the residual-velocity field of OB associations within 3 kpc of
the Sun has revealed periodic variations in the radial residual velocities
along the Galactic radius vector with a typical scale length of
lambda=2.0(+/-0.2) kpc and a mean amplitude of fR=7(+/-1) km/s. The fact that
the radial residual velocities of almost all OB-associations in rich
stellar-gas complexes are directed toward the Galactic center suggests that the
solar neighborhood under consideration is within the corotation radius. The
azimuthal-velocity field exhibits a distinct periodic pattern in the region
0<l<180 degrees, where the mean azimuthal-velocity amplitude is ft=6(+/-2)
km/s. There is no periodic pattern of the azimuthal-velocity field in the
region 180<l<360 degrees. The locations of the Cygnus arm, as well as the
Perseus arm, inferred from an analysis of the radial- and azimuthal-velocity
fields coincide. The periodic patterns of the residual-velocity fields of
Cepheids and OB associations share many common features.


title:
Solving of the fractional non-linear and linear Schrodinger equations by
  homotopy perturbation method

abstract: This paper has been withdrawn by the author


title:
NICEST, a near-infrared color excess method tailored for small-scale
  structures

abstract:
  Observational data and theoretical calculations show that significant
small-scale substructures are present in dark molecular clouds. These
inhomogeneities can provide precious hints on the physical conditions inside
the clouds, but can also severely bias extinction measurements. We present
NICEST, a novel method to account and correct for inhomogeneities in molecular
cloud extinction studies. The method, tested against numerical simulations,
removes almost completely the biases introduced by sub-pixel structures and by
the contamination of foreground stars. We applied NICEST to 2MASS data of the
Pipe molecular complex. The map thereby obtained shows significantly higher (up
to 0.41 mag in A_K) extinction peaks than the standard NICER (Lombardi et al.
2001) map. This first application confirms that substructures in nearby
molecular clouds, if not accounted for, can significantly bias extinction
measurements in regions with A_K > 1 mag; the effect, moreover, is expected to
increase in more distant molecular cloud, because of the poorer physical
resolution achievable.


title:
Changing Assembly Modes without Passing Parallel Singularities in
  Non-Cuspidal 3-R\underline{P}R Planar Parallel Robots

abstract:
  This paper demonstrates that any general 3-DOF three-legged planar parallel
robot with extensible legs can change assembly modes without passing through
parallel singularities (configurations where the mobile platform loses its
stiffness). While the results are purely theoretical, this paper questions the
very definition of parallel singularities.


title: Resolvent estimates for operators belonging to exponential classes

abstract:
  For $a,\alpha>0$ let $E(a,\alpha)$ be the set of all compact operators $A$ on
a separable Hilbert space such that $s_n(A)=O(\exp(-an^\alpha))$, where
$s_n(A)$ denotes the $n$-th singular number of $A$. We provide upper bounds for
the norm of the resolvent $(zI-A)^{-1}$ of $A$ in terms of a quantity
describing the departure from normality of $A$ and the distance of $z$ to the
spectrum of $A$. As a consequence we obtain upper bounds for the Hausdorff
distance of the spectra of two operators in $E(a,\alpha)$.


title:
Single-walled carbon nanotube weak links: from Fabry-P\'{e}rot to Kondo
  regime

abstract:
  We have investigated proximity-induced supercurrents in single-walled carbon
nanotubes in the Kondo regime and compared them with supercurrents obtained on
the same tube with Fabry-P\'{e}rot resonances. Our data display a wide
distribution of Kondo temperatures \emph{$T_K$} = 1 - 14 K, and the measured
critical current $I_{CM}$ vs. \emph{$T_K$} displays two distinct branches;
these branches, distinguished by zero-bias splitting of the normal-state Kondo
conductance peak, differ by an order of magnitude at large values of $T_K$.
Evidence for renormalization of Andreev levels in Kondo regime is also found.


title: On extensions of covariantly finite subcategories

abstract:
  In \cite{GT}, Gentle and Todorov proved that in an abelian category with
enough projective objects, the extension subcategory of two covariantly finite
subcategories is still covariantly finite. We give an counterexample to show
that Gentle-Todorov's theorem may fail in arbitrary abelian categories; we also
prove that a triangulated version of Gentle-Todorov's theorem holds; we make
applications of Gentle-Todorov's theorem to obtain short proofs to a classical
result by Ringel and a recent result by Krause and Solberg.


title: Shear Viscosity and Chern-Simons Diffusion Rate from Hyperbolic Horizons

abstract:
  We calculate the shear viscosity and anomalous baryon number violation rate
in quantum field theories at finite temperature having gravity duals with
hyperbolic horizons. We find the explicit dependence of these quantities on the
temperature. We show that the ratio of shear viscosity to entropy density is
below $1/(4\pi)$ at all temperatures and it can be made arbitrarily small in
the low temperature limit.


title:
Exciton-plasmon states in nanoscale materials: breakdown of the
  Tamm-Dancoff approximation

abstract:
  Within the Tamm-Dancoff approximation ab initio approaches describe excitons
as packets of electron-hole pairs propagating only forward in time. However, we
show that in nanoscale materials excitons and plasmons hybridize, creating
exciton--plasmon states where the electron-hole pairs oscillate back and forth
in time. Then, as exemplified by the trans-azobenzene molecule and carbon
nanotubes, the Tamm-Dancoff approximation yields errors as large as the
accuracy claimed in ab initio calculations. Instead, we propose a general and
efficient approach that avoids the Tamm--Dancoff approximation, and correctly
describes excitons, plasmons and exciton-plasmon states.


title:
Effective convergence of the 2PI-1/N expansion for nonequilibrium
  quantum fields

abstract:
  The 1/N expansion of the two-particle irreducible effective action offers a
powerful approach to study quantum field dynamics far from equilibrium. We
investigate the effective convergence of the 1/N expansion in the O(N) model by
comparing results obtained numerically in 1+1 dimensions at leading,
next-to-leading and next-to-next-to-leading order in 1/N as well as in the weak
coupling limit. A comparison in classical statistical field theory, where exact
numerical results are available, is made as well. We focus on early-time
dynamics and quasi-particle properties far from equilibrium and observe rapid
effective convergence already for moderate values of 1/N or the coupling.


title: Initial-Boundary Value Problems for Parabolic Equations

abstract:
  We prove new existence and uniqueness results for weak solutions to
non-homogeneous initial-boundary value problems for parabolic equations modeled
on the evolution of the p-Laplacian.


title:
The gravitomagnetic influence on Earth-orbiting spacecrafts and on the
  lunar orbit

abstract:
  Gravitomagnetic field is covariantly split in the {\it intrinsic} and {\it
extrinsic} parts, which are generated by rotational and translational currents
of matter respectively. The {\it intrinsic} component has been recently
discovered in the LAGEOS spacecraft experiment. We discuss the method of
detection of the {\it extrinsic} tidal component with the lunar laser ranging
(LLR) technique. Analysis of the gauge residual freedom in the relativistic
theory of three-body problem demonstrates that LLR is currently not capable to
detect the {\it extrinsic} gravitomagnetic effects which are at the ranging
level of few millimeters. Its detection requires further advances in the LLR
technique that are coming in the next 5-10 years.


title:
Combined microstructural and magneto optical study of current flow in
  polycrystalline forms of Nd and Sm Fe-oxypnictides

abstract:
  In order to understand why the inter- and intra-granular current densities of
polycrystalline superconducting oxypnictides differ by three orders of
magnitude, we have conducted combined magneto-optical and microstructural
examinations of representative randomly oriented polycrystalline Nd and Sm
single-layer oxypnictides. Magneto optical images show that the highest Jc
values are observed within single grains oriented with their c axes
perpendicular to the observation plane, implying that the intragranular current
is anisotropic. The much lower intergranular Jc is at least partially due to
many extrinsic factors, because cracks and a ubiquitous wetting As-Fe phase are
found at many grain boundaries. However, some grain boundaries are structurally
clean under high resolution transmission electron microscopy examination.
Because the whole-sample global Jc(5K) values of the two samples examined are
1000-4000 A/cm2, some 10-40 times that found in random, polycrystalline
YBa2Cu3O7-x, it appears that the dominant obstruction to intergranular current
flow of many present samples is extrinsic, though some intrinsic limitation of
current flow across grain boundaries cannot yet be ruled out.


title: Tannaka duality for proper Lie groupoids

abstract:
  The main contribution of this thesis is a Tannaka duality theorem for proper
Lie groupoids. This result is obtained by replacing the category of smooth
vector bundles over the base manifold of a Lie groupoid with a larger category,
the category of smooth Euclidean fields, and by considering smooth actions of
Lie groupoids on smooth Euclidean fields. The notion of smooth Euclidean field
that is introduced here is the smooth, finite dimensional analogue of the
familiar notion of continuous Hilbert field. In the second part of the thesis,
ordinary smooth representations of Lie groupoids on smooth vector bundles are
systematically studied from the point of view of Tannaka duality, and various
results are obtained in this direction.


title: Scale invariance, unimodular gravity and dark energy

abstract:
  We demonstrate that the combination of the ideas of unimodular gravity, scale
invariance, and the existence of an exactly massless dilaton leads to the
evolution of the universe supported by present observations: inflation in the
past, followed by the radiation and matter dominated stages and accelerated
expansion at present. All mass scales in this type of theories come from one
and the same source.


title: Fluxonic Cellular Automata

abstract:
  We formulate a new concept for computing with quantum cellular automata
composed of arrays of nanostructured superconducting devices. The logic states
are defined by the position of two trapped flux quanta (vortices) in a 2x2
blind-hole-matrix etched on a mesoscopic superconducting square. Such small
computational unit-cells are well within reach of current fabrication
technology. In an array of unit-cells, the vortex configuration of one cell
influences the penetrating flux lines in the neighboring cell through the
screening currents. Alternatively, in conjoined cells, the information transfer
can be strengthened by the interactions between the supercurrents in adjacent
cells. Here we present the functioning logic gates based on this fluxonic
cellular automata (FCA), where the logic operations are verified through
theoretical simulations performed in the framework of the time-dependent
Ginzburg-Landau theory. The input signals are defined by current loops placed
on top of the two diagonal blind holes of the input cell. For given
current-polarization, external flux lines are attracted or repelled by the
loops, forming the '0' or '1' configuration. The read-out technology may be
chosen from a large variety of modern vortex imaging methods, transport and
LDOS measurements.


title: Starbursts and torus evolution in AGN

abstract:
  Recent VLT SINFONI observations of the close environments (~30pc) of nearby
AGNs have shown that thick gas tori and starbursts with ages between 10 and
150Myr are frequently found. By applying these observations to a previously
established analytical model of clumpy accretion disks, we suggest an
evolutionary sequence for starburst and AGN phases. Whereas the observed
properties of the gas tell us about the current state of the torus, the
starburst characteristics provide information on the history of the torus. In
the suggested evolution, a torus passes through 3 different phases
predetermined by an external mass accretion rate. Started by an initial, short,
and massive gas infall, a turbulent and stellar wind-driven Q~1 disk is formed
in which the starburst proceeds. Once the supernovae explode the intercloud
medium is removed, leaving a massive, geometrically thick, collisional disk
with a decreasing, but still high-mass accretion rate. When the mass accretion
rate has significantly decreased, the collisional torus becomes thin and
transparent as the circumnuclear disk in the Galactic center of the Milky Way.
Variations on this scenario are possible either when there is a second short
and massive gas infall, in which case the torus may switch back into the
starburst mode, or when there is no initial short massive gas infall. All
observed tori up to now have been collisional and thick. The observations show
that this phase can last more than 100Myr. During this phase the decrease in
the mass accretion rate within the torus is slow (a factor of 4 within 150Myr).
The collisional tori also form stars, but with an efficiency of about 10% when
compared to a turbulent disk.


title: Thermal non-Gaussianity in holographic cosmology

abstract:
  Recently it has been shown that the thermal holographic fluctuations can give
rise to an almost scale invariant spectrum of metric perturbations since in
this scenario the energy is proportional to the area of the boundary rather
than the volume. Here we calculate the non-Gaussianity of the spectrum of
cosmological fluctuations in holographic phase, which can imprint on the
radiation dominated universe by an abrupt transition. We find that if the
matter is phantom-like, the non-Gaussianity $f_{NL}^{equil}$ can reach ${\cal
O}(1)$ or even be larger than ${\cal O}(1)$. Especially in the limit $\omega\to
-5/3$, the non-Gaussianity is very large and negative. Furthermore, since the
energy is proportional to the area, the thermal holographic non-Gaussianity
depends linearly on $k$ if we neglect the variation in $T$ during the
transition (fixed temperature).


title:
Termination of star formation by BH feedback in equal- and unequal-mass
  mergers of disk and elliptical galaxies

abstract:
  We present binary galaxy merger simulations of gas-rich disks (Sp-Sp), of
early-type galaxies and disks (E-Sp, mixed mergers), and mergers of early-type
galaxies (E-E, dry mergers) with varying mass ratios and different progenitor
morphologies. The simulations include radiative cooling, star formation and
black hole (BH) accretion and the associated feedback processes. We find for
Sp-Sp mergers, that the peak star formation rate and BH accretion rate decrease
and the growth timescales of the central black holes and newly formed stars
increase with higher progenitor mass ratios. The termination of star formation
by BH feedback in disk mergers is significantly less important for higher
progenitor mass ratios (e.g. 3:1 and higher). In addition, the inclusion of BH
feedback suppresses efficiently star formation in dry E-E mergers and mixed
E-Sp mergers.


title:
Abundance of regular orbits and out-of-equilibrium phase transitions in
  the thermodynamic limit for long-range systems

abstract:
  We investigate the dynamics of many-body long-range interacting systems,
taking the Hamiltonian Mean Field model as a case study. We show that an
abundance of regular trajectories, associated with invariant tori of the
single-particle dynamics, exists. The presence of such tori provides a
dynamical interpretation of the emergence of long-lasting out-of-equilibrium
regimes observed generically in long-range systems. This is alternative to a
previous statistical mechanics approach to such phenomena which was based on a
maximum entropy principle. Previously detected out-of-equilibrium phase
transitions are also reinterpreted within this framework.


title:
Probing the equilibrium dynamics of colloidal hard spheres above the
  mode-coupling glass transition

abstract:
  We use dynamic light scattering and computer simulations to study equilibrium
dynamics and dynamic heterogeneity in concentrated suspensions of colloidal
hard spheres. Our study covers an unprecedented density range and spans seven
decades in structural relaxation time, $\ta$, including equilibrium easurements
above $\phi_{\rm c}$, the location of the glass transition deduced from fitting
our data to mode-coupling theory. Instead of falling out of equilibrium, the
system remains ergodic above $\phi_{\rm c}$ and enters a new dynamical regime
where $\ta$ increases with a functional form that was not anticipated by
previous experiments, while the amplitude of dynamic heterogeneity grows slower
than a power law with $\ta$, as found in molecular glass-formers close to the
glass transition.


title: A Non-Fermi Liquid from a Charged Black Hole; A Critical Fermi Ball

abstract:
  Using the AdS/CFT correspondence, we calculate a fermionic spectral function
in a 2+1 dimensional non-relativistic quantum field theory which is dual to a
gravitational theory in the $AdS_4$ background with a charged black hole. The
spectral function shows no quasiparticle peak but the Fermi surface is still
well defined. Interestingly, all momentum points inside the Fermi surface are
critical and the gapless modes are defined in a {\it critical Fermi ball} in
the momentum space.


title:
Constraining the nature of galaxy haloes with gravitational mesolensing
  of QSOs by halo substructure objects

abstract:
  Gravitational lensing of background compact objects like active galactic
nuclei and quasars, by extended intermediate mass lenses such as globular
clusters and and dark matter clumps with masses 10^5 - 10^8 M_sun, is
considered. It is shown that observational study of the galaxy-quasar's
associations is a powerful direct observational test of the nature of massive
galaxy haloes. Optical interferometric observations with VLTI and Keck
instruments are able to constrain masses and number of substructure halo
objects. Evidence of gravitational lensing by globular clusters in haloes of
spiral and elliptical galaxies is presented.


title: The impact of Early Dark Energy on non-linear structure formation

abstract:
  We study non-linear structure formation in high-resolution simulations of
Early Dark Energy (EDE) cosmologies and compare their evolution with the
standard LCDM model. Extensions of the spherical top-hat collapse model predict
that the virial overdensity and linear threshold density for collapse should be
modified in EDE model, yielding significant modifications in the expected halo
mass function. Here we present numerical simulations that directly test these
expectations. Interestingly, we find that the Sheth & Tormen formalism for
estimating the abundance of dark matter halos continues to work very well in
its standard form for the Early Dark Energy cosmologies, contrary to analytic
predictions. The residuals are even slightly smaller than for LCDM. We also
study the virial relationship between mass and dark matter velocity dispersion
in different dark energy cosmologies, finding excellent agreement with the
normalization for Lambda as calibrated by Evrard et al.(2008). The earlier
growth of structure in EDE models relative to LCDM produces large differences
in the mass functions at high redshift. This could be measured directly by
counting groups as a function of the line-of-sight velocity dispersion,
skirting the ambiguous problem of assigning a mass to the halo. Using dark
matter substructures as a proxy for member galaxies, we demonstrate that even
with 3-5 members sufficiently accurate measurements of the halo velocity
dispersion function are possible. Finally, we determine the concentration-mass
relationship for our EDE cosmologies. Consistent with the earlier formation
time, the EDE halos show higher concentrations at a given halo mass. We find
that the magnitude of the difference in concentration is well described by the
prescription of Eke et al.(2001) for estimating halo concentrations.


title: Analysis of Fourier transform valuation formulas and applications

abstract:
  The aim of this article is to provide a systematic analysis of the conditions
such that Fourier transform valuation formulas are valid in a general
framework; i.e. when the option has an arbitrary payoff function and depends on
the path of the asset price process. An interplay between the conditions on the
payoff function and the process arises naturally. We also extend these results
to the multi-dimensional case, and discuss the calculation of Greeks by Fourier
transform methods. As an application, we price options on the minimum of two
assets in L\'evy and stochastic volatility models.


title: Quantum scale invariance, cosmological constant and hierarchy problem

abstract:
  We construct a class of theories which are scale invariant on quantum level
in all orders of perturbation theory. In a subclass of these models scale
invariance is spontaneously broken, leading to the existence of a massless
dilaton. The applications of these results to the problem of stability of the
electroweak scale against quantum corrections, to the cosmological constant
problem and to dark energy are discussed.


title: Observation of a gradient catastrophe generating solitons

abstract:
  We investigate the propagation of a dark beam in a defocusing medium in the
strong nonlinear regime. We observe for the first time a shock fan filled with
non-interacting one-dimensional grey solitons that emanates from a gradient
catastrophe developing around a null of the optical intensity. Remarkably this
scenario turns out to be very robust, persisting also when the material
nonlocal response averages the nonlinearity over dimensions much larger than
the emerging soliton filaments.


title:
Controlling an actively-quenched single photon detector with bright
  light

abstract:
  We control using bright light an actively-quenched avalanche single-photon
detector. Actively-quenched detectors are commonly used for quantum key
distribution (QKD) in the visible and near-infrared range. This study shows
that these detectors are controllable by the same attack used to hack
passively-quenched and gated detectors. This demonstrates the generality of our
attack and its possible applicability to eavsdropping the full secret key of
all QKD systems using avalanche photodiodes (APDs). Moreover, the commercial
detector model we tested (PerkinElmer SPCM-AQR) exhibits two new blinding
mechanisms in addition to the previously observed thermal blinding of the APD,
namely: malfunctioning of the bias voltage control circuit, and overload of the
DC/DC converter biasing the APD. These two new technical loopholes found just
in one detector model suggest that this problem must be solved in general, by
incorporating generally imperfect detectors into the security proof for QKD.


title:
Optical frequency synthesis and measurement using fibre-based
  femtosecond lasers

abstract:
  We report the synthesis and measurement of an ultra-precise and extremely
stable optical frequency in the telecommunications window around 1543 nm. Using
a fibre-based femtosecond frequency comb we have phase-stabilised a fibre laser
at 194 THz to an optical frequency standard at 344 THz, thus transferring the
properties of the optical frequency standard to another spectral region.
Relative to the optical frequency standard, the synthesised frequency at 194
THz is determined to within 1 mHz and its fractional frequency instability is
measured to be less than 2*10^{-15} at 1 s, reaching 5*10^{-18} after 8000 s.
We also measured the synthesised frequency against a caesium fountain clock:
here the frequency comparison itself contributes less than 4 mHz (2*10^{-17})
to the uncertainty. Our results confirm the suitability of fibre based
frequency comb technology for precision measurements and frequency synthesis,
and enable long-distance comparison of optical clocks by using optical fibres
to transmit the frequency information.


title: Christoffel words and Markoff triples

abstract: Markoff triples are parametrized uniquely by Christoffel words.


title:
Photometry using the Infrared Array Camera on the Spitzer Space
  Telescope

abstract:
  We present several corrections for point source photometry to be applied to
data from the Infrared Array Camera (IRAC) on the Spitzer Space Telescope.
These corrections are necessary because of characteristics of the IRAC arrays
and optics and the way the instrument is calibrated in-flight. When these
corrections are applied, it is possible to achieve a ~2% relative photometric
accuracy for sources of adequate signal to noise in an IRAC image.


title:
Gravitational waves from resolvable massive black hole binary systems
  and observations with Pulsar Timing Arrays

abstract:
  Massive black holes are key components of the assembly and evolution of
cosmic structures and a number of surveys are currently on-going or planned to
probe the demographics of these objects and to gain insight into the relevant
physical processes. Pulsar Timing Arrays (PTAs) currently provide the only
means to observe gravitational radiation from massive black hole binary systems
with masses >10^7 solar masses. The whole cosmic population produces a
stochastic background that could be detectable with upcoming Pulsar Timing
Arrays. Sources sufficiently close and/or massive generate gravitational
radiation that significantly exceeds the level of the background and could be
individually resolved. We consider a wide range of massive black hole binary
assembly scenarios, we investigate the distribution of the main physical
parameters of the sources, such as masses and redshift, and explore the
consequences for Pulsar Timing Arrays observations. Depending on the specific
massive black hole population model, we estimate that on average at least one
resolvable source produces timing residuals in the range ~5-50 ns. Pulsar
Timing Arrays, and in particular the future Square Kilometre Array (SKA), can
plausibly detect these unique systems, although the events are likely to be
rare. These observations would naturally complement on the high-mass end of the
massive black hole distribution function future surveys carried out by the
Laser Interferometer Space Antenna (LISA)


title: Structure computation and discrete logarithms in finite abelian p-groups

abstract:
  We present a generic algorithm for computing discrete logarithms in a finite
abelian p-group H, improving the Pohlig-Hellman algorithm and its
generalization to noncyclic groups by Teske. We then give a direct method to
compute a basis for H without using a relation matrix. The problem of computing
a basis for some or all of the Sylow p-subgroups of an arbitrary finite abelian
group G is addressed, yielding a Monte Carlo algorithm to compute the structure
of G using O(|G|^0.5) group operations. These results also improve generic
algorithms for extracting pth roots in G.


title:
Round Table Discussion at the Final Session of FPCP 2008: The Future of
  Flavor Physics and CP

abstract:
  The final session of FPCP 2008 consisted of a round-table discussion among
panelists and audience. The panelists included Jeffrey Appel(moderator), Martin
Beneke, George W.S. Hou, David Kirkby, Dmitri Tsybychev, Matt Wingate, and Taku
Yamanaka. What follows is an edited transcript of the session.


title: Ten weeks in the life of an eDonkey server

abstract:
  This paper presents a capture of the queries managed by an eDonkey server
during almost 10 weeks, leading to the observation of almost 9 billion messages
involving almost 90 million users and more than 275 million distinct files.
Acquisition and management of such data raises several challenges, which we
discuss as well as the solutions we developed. We obtain a very rich dataset,
orders of magnitude larger than previously avalaible ones, which we provide for
public use. We finally present basic analysis of the obtained data, which
already gives evidence of non-trivial features.


title:
Explicit characterization of the identity configuration in an Abelian
  Sandpile Model

abstract:
  Since the work of Creutz, identifying the group identities for the Abelian
Sandpile Model (ASM) on a given lattice is a puzzling issue: on rectangular
portions of Z^2 complex quasi-self-similar structures arise. We study the ASM
on the square lattice, in different geometries, and a variant with directed
edges. Cylinders, through their extra symmetry, allow an easy determination of
the identity, which is a homogeneous function. The directed variant on square
geometry shows a remarkable exact structure, asymptotically self-similar.

categories: cond-mat.stat-mech hep-lat math-ph math.MP nlin.AO


title: G-biliaison of ladder Pfaffian varieties

abstract:
  The ideals generated by pfaffians of mixed size contained in a subladder of a
skew-symmetric matrix of indeterminates define arithmetically Cohen-Macaulay,
projectively normal, reduced and irreducible projective varieties. We show that
these varieties belong to the G-biliaison class of a complete intersection. In
particular, they are glicci.


title: Network effects in a human capital based economic growth model

abstract:
  We revisit a recently introduced agent model[ACS {\bf 11}, 99 (2008)], where
economic growth is a consequence of education (human capital formation) and
innovation, and investigate the influence of the agents' social network, both
on an agent's decision to pursue education and on the output of new ideas.
Regular and random networks are considered. The results are compared with the
predictions of a mean field (representative agent) model.


title: Charmonium production in e+e- to \psi + X(c\bar c) and e+e- to D*D_J

abstract:
  The dominance of chi_0 in the data for e+e- to psi + chi_J(c\bar{c}) is shown
to violate OZI factorization. Single gluon exchange gives a non-factorizing
effective S.L interaction that generates a large scalar production amplitude.
This also has observable effects near threshold in e+e- to D*D_J, where
enhancements of D*D_0 and DD_1 channels are predicted. Further tests and
implications are discussed.


title:
Quotients of products of curves, new surfaces with $p_g=0$ and their
  fundamental groups

abstract:
  The first main purpose of this paper is to contribute to the existing
knowledge about the complex projective surfaces $S$ of general type with
$p_g(S) = 0$ and their moduli spaces, constructing 19 new families of such
surfaces with hitherto unknown fundamental groups. We also provide a table
containing all the known such surfaces with K^2 <=7.
  Our second main purpose is to describe in greater generality the fundamental
groups of smooth projective varieties which occur as the minimal resolutions of
the quotient of a product of curves by the action of a finite group.
  We classify, in the two dimensional case, all the surfaces with q=p_g = 0
obtained as the minimal resolution of such a quotient, having rational double
points as singularities. We show that all these surfaces give evidence to the
Bloch conjecture.


title:
Sub-exponentially localized kernels and frames induced by orthogonal
  expansions

abstract:
  The aim of this paper is to construct sup-exponentially localized kernels and
frames in the context of classical orthogonal expansions, namely, expansions in
Jacobi polynomials, spherical harmonics, orthogonal polynomials on the ball and
simplex, and Hermite and Laguerre functions.


title:
New Generation of Massless Dirac Fermions in Graphene under External
  Periodic Potentials

abstract:
  We show that new massless Dirac fermions are generated when a slowly varying
periodic potential is applied to graphene. These quasiparticles, generated near
the supercell Brillouin zone boundaries with anisotropic group velocity, are
different from the original massless Dirac fermions. The quasiparticle
wavevector (measured from the new Dirac point), the generalized pseudospin
vector, and the group velocity are not collinear. We further show that with an
appropriate periodic potential of triangular symmetry, there exists an energy
window over which the only available states are these quasiparticles, thus,
providing a good system to probe experimentally the new massless Dirac
fermions. The required parameters of external potentials are within the realm
of laboratory conditions.


title: CP Violation in B0 decays to Charmonium and Charm Final States at BaBar

abstract:
  We report on measurements of time-dependent CP-violation asymmetries in
neutral B meson decays to charmonium and charm final states. The results are
obtained from a data sample of 467+/-5 million Y(4S)->BBbar decays collected
with the BaBar detector at the PEP-II B factory.


title:
Methods for detecting flaring structures in Sagittarius A* with high
  frequency VLBI

abstract:
  The super massive black hole candidate, Sagittarius A*, exhibits variability
from radio to X-ray wavelengths on time scales that correspond to < 10
Schwarzschild radii. We survey the potential of millimeter-wavelength VLBI to
detect and constrain time variable structures that could give rise to such
variations, focusing on a model in which an orbiting hot spot is embedded in an
accretion disk. Non-imaging algorithms are developed that use interferometric
closure quantities to test for periodicity, and applied to an ensemble of
hot-spot models that sample a range of parameter space. We find that structural
periodicity in a wide range of cases can be detected on most potential VLBI
arrays using modern VLBI instrumentation. Future enhancements of mm/sub-mm VLBI
arrays including phased array processors to aggregate VLBI station collecting
area, increased bandwidth recording, and addition of new VLBI sites all
significantly aid periodicity detection. The methods described herein can be
applied to other models of Sagittarius A*, including jet outflows and
Magneto-Hydrodynamic accretion simulations.


title: Model Theoretic Complexity of Automatic Structures

abstract:
  We study the complexity of automatic structures via well-established concepts
from both logic and model theory, including ordinal heights (of well-founded
relations), Scott ranks of structures, and Cantor-Bendixson ranks (of trees).
We prove the following results: 1) The ordinal height of any automatic well-
founded partial order is bounded by \omega^\omega ; 2) The ordinal heights of
automatic well-founded relations are unbounded below the first non-computable
ordinal; 3) For any computable ordinal there is an automatic structure of Scott
rank at least that ordinal. Moreover, there are automatic structures of Scott
rank the first non-computable ordinal and its successor; 4) For any computable
ordinal, there is an automatic successor tree of Cantor-Bendixson rank that
ordinal.


title:
Superfluid and Fermi liquid phases of Bose-Fermi mixtures in optical
  lattices

abstract:
  We describe interacting mixtures of ultracold bosonic and fermionic atoms in
harmonically confined optical lattices. For a suitable choice of parameters we
study the emergence of superfluid and Fermi liquid (non-insulating) regions out
of Bose-Mott and Fermi-band insulators, due to finite Boson and Fermion
hopping. We obtain the shell structure for the system and show that angular
momentum can be transferred to the non-insulating regions from
Laguerre-Gaussian beams, which combined with Bragg spectroscopy can reveal all
superfluid and Fermi liquid shells.


title: Doping a Mott insulator with orbital degrees of freedom

abstract:
  We study the effects of hole doping on one-dimensional Mott insulators with
orbital degrees of freedom. We describe the system in terms of a generalized
t-J model. At a specific point in parameter space the model becomes integrable
in analogy to the one-band supersymmetric t-J model. We use the Bethe ansatz to
derive a set of nonlinear integral equations which allow us to study the
thermodynamics exactly. Moving away from this special point in parameter space
we use the density-matrix renormalization group applied to transfer matrices to
study the evolution of various phases of the undoped system with doping and
temperature. Finally, we study a one-dimensional version of a realistic model
for cubic titanates which includes the anisotropy of the orbital sector due to
Hund's coupling. We find a transition from a phase with antiferromagnetically
correlated spins to a phase where the spins are fully ferromagnetically
polarized, a strong tendency towards phase separation at large Hund's coupling,
as well as the possibility of an instability towards triplet superconductivity.


title: Gravitational Geometric Phase in the Presence of Torsion

abstract:
  We investigate the relativistic and non-relativistic quantum dynamics of a
neutral spin-1/2 particle submitted an external electromagnetic field in the
presence of a cosmic dislocation. We analyze the explicit contribution of the
torsion in the geometric phase acquired in the dynamic of this neutral
spinorial particle. We discuss the influence of the torsion in the relativistic
geometric phase. Using the Foldy-Wouthuysen approximation, the non-relativistic
quantum dynamics are studied and the influence of the torsion in the
Aharonov-Casher and He-McKellar-Wilkens effects are discussed.


title: SL(2,R)-Symmetry and Noncommutative Phase Space in (2+2) Dimensions

abstract:
  We generalize the connection between 2t physics and noncommutative geometry.
In particular, we apply our formalism to a target spacetime of signature (2+2).
Specifically, we compute an algebra of a generalized SL(2, R)-Hamiltonian
constraint, showing that it satisfies a kind of algebra associated with the
noncommutative group $U_{\star}(1,1)$. We also comment about a possible
connection between our formalism and nonsymmetric gravitational theory.


title: Three Lectures on Automatic Structures

abstract:
  This paper grew out of three tutorial lectures on automatic structures given
by the first author at the Logic Colloquium 2007. We discuss variants of
automatic structures related to several models of computation: word automata,
tree automata, Buchi automata, and Rabin automata. Word automata process finite
strings, tree automata process finite labeled trees, Buchi automata process
infinite strings, and Rabin automata process infinite binary labeled trees.
Automatic structures are mathematical objects which can be represented by
(word, tree, Buchi, or Rabin) automata. The study of properties of automatic
structures is a relatively new and very active area of research.


title: Heavy quark distribution function in hadrons

abstract:
  The moments of the heavy quark-parton distribution functions in a heavy
pseudoscalar meson, obtained in QCD sum rules, are expanded in the inverse
heavy quark. Comparison with the finite mass results reveals that while the
heavy mass expansion works reasonably well for the $b$ quark, one has to take
into account terms of higher than $(1/m_c)^2$ order for the $c$ quark.


title: Stringy Instantons as Strong Dynamics

abstract:
  We study the relation between stringy instantons and strong dynamics effects
in type IIB toric quiver gauge theories. By exploiting the involutive property
of Seiberg duality we relate the classical constraint on the moduli space of
the gauge theory with the stringy instanton contribution to the superpotential.
The result holds for unitary, orthogonal and symplectic gauge groups.


title:
Post-Newtonian limitations on measurement of the PPN parameters caused
  by motion of gravitating bodies

abstract:
  We derive explicit Lorentz-invariant solution of the Einstein and null
geodesic equations for data processing of the time delay and ranging
experiments in gravitational field of moving gravitating bodies of the solar
system - the Sun and major planets. We discuss general-relativistic
interpretation of these experiments and the limitations imposed by motion of
the massive bodies on measurement of the parameters gamma_{PPN}, beta_{PPN} and
delta_{PPN} of the parameterized post-Newtonian formalism.


title: A family of Schr\"odinger operators whose spectrum is an interval

abstract:
  By approximation, I show that the spectrum of the Schr\"odinger operator with
potential $V(n) = f(n\rho \pmod 1)$ for f continuous and $\rho > 0$, $\rho
\notin \N$ is an interval.


title:
Higher-dimensional Embedding of Four-dimensional Hypersurfaces:
  Chronological Development of Co-dimension-1 Embedding

abstract:
  Here we present an overview of the work done over the years on the embedding
of hypersurfaces in a space of higher dimension, with particular reference to
the embedding of four-dimensional hypersurfaces in five-dimensional
space-times. The concept of embedding was developed by geometers starting from
Gauss. Applications in physics started with the embedding of the Schwarzschild
metric and through the works of Kaluza and Klein. The program on the embedding
of four-dimensional hypersurfaces in five-dimensional spacetimes gathered
strength with the formulation of the induced matter theory by Wesson and his
collaborators. Close on its heels followed the works on the braneworld
scenario. Simultaneously, the mathematical aspects of the embedding of
four-dimensional hypersurfaces in five-dimensional spacetimes were developed as
an application of the Campbell-Magaard theorem. In this paper we have tried to
have a panoramic view of the major works done in these fields and have tried to
focus on the recent trends in this context.


title: Localization Bounds for Multiparticle Systems

abstract:
  We consider the spectral and dynamical properties of quantum systems of $n$
particles on the lattice $\Z^d$, of arbitrary dimension, with a Hamiltonian
which in addition to the kinetic term includes a random potential with iid
values at the lattice sites and a finite-range interaction. Two basic
parameters of the model are the strength of the disorder and the strength of
the interparticle interaction. It is established here that for all $n$ there
are regimes of high disorder, and/or weak enough interactions, for which the
system exhibits spectral and dynamical localization. The localization is
expressed through bounds on the transition amplitudes, which are uniform in
time and decay exponentially in the Hausdorff distance in the configuration
space. The results are derived through the analysis of fractional moments of
the $n$-particle Green function, and related bounds on the eigenfunction
correlators.


title:
MultiNest: an efficient and robust Bayesian inference tool for cosmology
  and particle physics

abstract:
  We present further development and the first public release of our multimodal
nested sampling algorithm, called MultiNest. This Bayesian inference tool
calculates the evidence, with an associated error estimate, and produces
posterior samples from distributions that may contain multiple modes and
pronounced (curving) degeneracies in high dimensions. The developments
presented here lead to further substantial improvements in sampling efficiency
and robustness, as compared to the original algorithm presented in Feroz &
Hobson (2008), which itself significantly outperformed existing MCMC techniques
in a wide range of astrophysical inference problems. The accuracy and economy
of the MultiNest algorithm is demonstrated by application to two toy problems
and to a cosmological inference problem focussing on the extension of the
vanilla $\Lambda$CDM model to include spatial curvature and a varying equation
of state for dark energy. The MultiNest software, which is fully parallelized
using MPI and includes an interface to CosmoMC, is available at
http://www.mrao.cam.ac.uk/software/multinest/. It will also be released as part
of the SuperBayeS package, for the analysis of supersymmetric theories of
particle physics, at http://www.superbayes.org


title: On the isometric composition operators on the Bloch space in C^n

abstract:
  Let phi be a holomorphic self-map of a bounded homogeneous domain D in C^n.
In this work, we show that the composition operator C_phi is bounded on the
Bloch space B of the domain and provide estimates on its operator norm. We also
give a sufficient condition for phi to induce an isometry on B. This condition
allows us to construct non-trivial examples of isometric composition operators
in the case when D has the unit disk as a factor. We then obtain some necessary
conditions for C_phi to be an isometry on B when D is a Cartan classical
domain. Finally, we give the complete description of the spectrum of the
isometric composition operators in the case of the unit disk and for a wide
class of symbols on the polydisk.


title:
Long-term operation of a multi-channel cosmic muon system based on
  scintillation counters with MRS APD light readout

abstract:
  A Cosmic Ray Test Facility (CRTF) is the first large-scale implementation of
a scintillation triggering system based on a new scintillation technique known
as START. In START, the scintillation light is collected and transported by WLS
optical fibers, while light detection is performed by pairs of avalanche
photodiodes with the Metal-Resistor-Semiconductor structure operated in the
Geiger mode (MRS APD). START delivers 100% efficiency of cosmic muon detection,
while its intrinsic noise level is less than 10^{-2} Hz. CRTF, consisting of
160 START channels, has been continuously operated by the ALICE TOF
collaboration for more than 25 000 hours, and has demonstrated a high level of
stability. Fewer than 10% of MRS APDs had to be replaced during this period.


title:
Axial invariance of rapidly varying diffusionless motions in the Earth's
  core interior

abstract:
  Geostrophic jets propagating as Alfv\'en waves are shown to arise ina rapidly
rotating spherical shell permeated by a magnetic field among the transient
motions set up by an impulsive rotation of the inner core. These axially
invariant motions evolve on a time-scale which is short compared to the
magnetic diffusion time. The numerical study is taken as illustrative of a more
general point: on such a fast time-scale the dimensionless number appropriate
to compare the rotation and magnetic forces is independent of the magnetic
diffusivity in contrast with the often used Elsasser number. Extension of the
analysis to non-axisymmetrical motions is supported by published studies of
dynamo models and magnetic instabilities.


title: Superstable groups acting on trees

abstract:
  We study superstable groups acting on trees. We prove that an action of an
$\omega$-stable group on a simplicial tree is trivial. This shows that an
HNN-extension or a nontrivial free product with amalgamation is not
$\omega$-stable. It is also shown that if $G$ is a superstable group acting
nontrivially on a $\Lambda$-tree, where $\Lambda=\mathbb Z$ or $\Lambda=\mathbb
R$, and if $G$ is either $\alpha$-connected and $\Lambda=\mathbb Z$, or if the
action is irreducible, then $G$ interprets a simple group having a nontrivial
action on a $\Lambda$-tree. In particular if $G$ is superstable and splits as
$G=G_1*_AG_2$, with the index of $A$ in $G_1$ different from 2, then $G$
interprets a simple superstable non $\omega$-stable group.
  We will deal with "minimal" superstable groups of finite Lascar rank acting
nontrivially on $\Lambda$-trees, where $\Lambda=\mathbb Z$ or $\Lambda=\mathbb
R$. We show that such groups $G$ have definable subgroups $H_1 \lhd H_2 \lhd
G$, $H_2$ is of finite index in $G$, such that if $H_1$ is not
nilpotent-by-finite then any action of $H_1$ on a $\Lambda$-tree is trivial,
and $H_2/H_1$ is either soluble or simple and acts nontrivially on a
$\Lambda$-tree. We are interested particularly in the case where $H_2/H_1$ is
simple and we show that $H_2/H_1$ has some properties similar to those of bad
groups.


title: Limits on isotropic Lorentz violation in QED from collider physics

abstract:
  We consider the possibility that Lorentz violation can generate differences
between the limiting velocities of light and charged matter. Such effects would
lead to efficient vacuum Cherenkov radiation or rapid photon decay. The absence
of such effects for 104.5 GeV electrons at the Large Electron Positron collider
and for 300 GeV photons at the Tevatron therefore constrains this type of
Lorentz breakdown. Within the context of the standard-model extension, these
ideas imply an experimental bound at the level of -5.8 x 10^{-12} <=
\tilde{\kappa}_{tr}-(4/3)c_e^{00} <= 1.2 x 10^{-11} tightening existing
laboratory measurements by 3-4 orders of magnitude. Prospects for further
improvements with terrestrial and astrophysical methods are discussed.


title: Hodge spectrum of hyperplane arrangements

abstract:
  In this article there are two main results. The first result gives a formula,
in terms of a log resolution, for the graded pieces of the Hodge filtration on
the cohomology of a unitary local system of rank one on the complement of an
arbitrary divisor in a smooth projective complex variety. The second result is
an application of the first. We give a combinatorial formula for the spectrum
of a hyperplane arrangement. M. Saito recently proved that the spectrum of a
hyperplane arrangement depends only on combinatorics. However, a combinatorial
formula was missing. The formula is achieved by a different method.


title: The ground state and the long-time evolution in the CMC Einstein flow

abstract:
  Let (g,K)(k) be a CMC (vacuum) Einstein flow over a compact three-manifold M
with non-positive Yamabe invariant (Y(M)). As noted by Fischer and Moncrief,
the reduced volume V(k)=(-k/3)^{3}Vol_{g(k)}(M) is monotonically decreasing in
the expanding direction and bounded below by V_{\inf}=(-1/6)Y(M))^{3/2}.
Inspired by this fact we define the ground state of the manifold M as "the
limit" of any sequence of CMC states {(g_{i},K_{i})} satisfying: i. k_{i}=-3,
ii. V_{i} --> V_{inf}, iii. Q_{0}((g_{i},K_{i}))< L where Q_{0} is the
Bel-Robinson energy and L is any arbitrary positive constant. We prove that (as
a geometric state) the ground state is equivalent to the Thurston
geometrization of M. Ground states classify naturally into three types. We
provide examples for each class, including a new ground state (the Double Cusp)
that we analyze in detail. Finally consider a long time and cosmologically
normalized flow (\g,\K)(s)=((-k/3)^{2}g,(-k/3))K) where s=-ln(-k) is in
[a,\infty). We prove that if E_{1}=E_{1}((\g,\K))< L (where E_{1}=Q_{0}+Q_{1},
is the sum of the zero and first order Bel-Robinson energies) the flow
(\g,\K)(s) persistently geometrizes the three-manifold M and the geometrization
is the ground state if V --> V_{inf}.


title:
Creation-annihilation processes in the ensemble of constant particle
  number

abstract:
  We study, in the ensemble of constant particle number, processes in which a
cluster of particles is annihilated and particles are created catalytically in
active sites. In this ensemble, particles belonging to a cluster of $\ell$
particles jump to $\ell$ distinct active sites. As examples of our
prescription, we analyze numerically three nonequilibrium systems that
annihilate cluster of particles that are identified as conserved versions of
the pair annihilation contact model, triplet annihilation contact model and
pair contact process. We show also how to set up the constant particle number
ensemble from the constant rate ensemble.


title: SDSSJ092712.65+294344.0: a candidate massive black hole binary

abstract:
  In this Letter we explore the hypothesis that the quasar
SDSSJ092712.65+294344.0 is hosting a massive black hole binary embedded in a
circumbinary disc. The lightest, secondary black hole is active, and gas
orbiting around it is responsible for the blue-shifted broad emission lines
with velocity off-set of 2650 km/s, relative to the galaxy rest frame. As the
tidal interaction of the binary with the outer disc is expected to excavate a
gap, the blue-shifted narrow emission lines are consistent with being emitted
from the low-density inhomogeneous gas of the hollow region. From the
observations we infer a binary mass ratio q ~ 0.3, a mass for the primary of M1
~ 2 billion Msun and a semi-major axis of 0.34 pc, corresponding to an orbital
period of 370 years. We use the results of cosmological merger trees to
estimate the likely-hood of observing SDSSJ092712.65+294344.0 as recoiling
black hole or as a binary. We find that the binary hypothesis is preferred
being one hundred times more probable than the ejection hypothesis. If
SDSSJ092712.65+294344.0 hosts a binary, it would be the one closest massive
black hole binary system ever discovered.


title: An Exploratory Study of Calendar Use

abstract:
  In this paper, we report on findings from an ethnographic study of how people
use their calendars for personal information management (PIM). Our participants
were faculty, staff and students who were not required to use or contribute to
any specific calendaring solution, but chose to do so anyway. The study was
conducted in three parts: first, an initial survey provided broad insights into
how calendars were used; second, this was followed up with personal interviews
of a few participants which were transcribed and content-analyzed; and third,
examples of calendar artifacts were collected to inform our analysis. Findings
from our study include the use of multiple reminder alarms, the reliance on
paper calendars even among regular users of electronic calendars, and wide use
of calendars for reporting and life-archival purposes. We conclude the paper
with a discussion of what these imply for designers of interactive calendar
systems and future work in PIM research.


title:
Spinning down newborn neutron stars: nonlinear development of the r-mode
  instability

abstract:
  We model the nonlinear saturation of the r-mode instability via three-mode
couplings and the effects of the instability on the spin evolution of young
neutron stars. We include one mode triplet consisting of the r-mode and two
near resonant inertial modes that couple to it. We find that the spectrum of
evolutions is more diverse than previously thought. The evolution of the star
is dynamic and initially dominated by fast neutrino cooling. Nonlinear effects
become important when the r-mode amplitude grows above its first parametric
instability threshold. The balance between neutrino cooling and viscous heating
plays an important role in the evolution. Depending on the initial r-mode
amplitude, and on the strength of the viscosity and of the cooling this balance
can occur at different temperatures. If thermal equilibrium occurs on the
r-mode stability curve, where gravitational driving equals viscous damping, the
evolution may be adequately described by a one-mode model. Otherwise, nonlinear
effects are important and lead to various more complicated scenarios. Once
thermal balance occurs, the star spins-down oscillating between thermal
equilibrium states until the instability is no longer active. For lower
viscosity we observe runaway behavior in which the r-mode amplitude passes
several parametric instability thresholds. In this case more modes need to be
included to model the evolution accurately. In the most optimistic case, we
find that gravitational radiation from the r-mode instability in a very young,
fast spinning neutron star within about 1 Mpc of Earth may be detectable by
advanced LIGO for years, and perhaps decades, after formation. Details
regarding the amplitude and duration of the emission depend on the internal
dissipation of the modes of the star, which would be probed by such detections.


title: Mean motion resonances from planet-planet scattering

abstract:
  Planet-planet scattering is the leading mechanism to explain the large
eccentricities of the observed exoplanet population. However, scattering has
not been considered important to the production of pairs of planets in mean
motion resonances (MMRs). We present results from a large number of numerical
simulations of dynamical instabilities in 3-planet systems. We show that MMRs
arise naturally in about five percent of cases. The most common resonances we
populate are the 2:1 and 3:1 MMRs, although a wide variety of MMRs can occur,
including high-order MMRs (up to eleventh order). MMRs are generated
preferentially in systems with uneven mass distributions: the smallest planet
is typically ejected after a series of close encounters, leaving the remaining,
more massive planets in resonance. The distribution of resonant planets is
consistent with the phase-space density of resonant orbits, meaning that
planets are randomly thrown into MMRs rather than being slowly pulled into
them. It may be possible to distinguish between MMRs created by scattering vs.
convergent migration in a gaseous disk by considering planetary mass ratios:
resonant pairs of planets beyond ~1 AU with more massive outer planets are
likely to have formed by scattering. In addition, scattering may be responsible
for pairs of planets in high-order MMRs (3:1 and higher) that are not easily
populated by migration. The frequency of MMRs from scattering is comparable to
the expected survival rate of MMRs in turbulent disks. Thus, planet-planet
scattering is likely to be a major contributor to the population of resonant
planets.


title: Non-Gaussian fluctuations near the QCD critical point

abstract:
  We study the effect of the QCD critical point on non-Gaussian moments
(cumulants) of fluctuations of experimental observables in heavy-ion
collisions. We find that these moments are very sensitive to the proximity of
the critical point, as measured by the magnitude of the correlation length xi.
For example, the cubic central moment of multiplicity ~ xi^4.5 and the quartic
cumulant ~ xi^7. We estimate the magnitude of critical point contributions to
non-Gaussian fluctuations of pion and proton multiplicities.


title: Large gauge invariant non-standard neutrino interactions

abstract:
  Theories beyond the Standard Model must necessarily respect its gauge
symmetry. This implies strict constraints on the possible models of
non-standard neutrino interactions, which we analyze. The focus is set on the
effective low-energy dimension six and eight operators involving four leptons,
decomposing them according to all possible tree-level mediators, as a guide for
model building. The new couplings are required to have sizeable strength, while
processes involving four charged leptons are required to be suppressed. For
non-standard interactions in matter, only diagonal tau-neutrino interactions
can escape these requirements and can be allowed to result from dimension six
operators. Large non-standard neutrino interactions from dimension eight
operators alone are phenomenologically allowed in all flavour channels and
shown to require at least two new mediator particles. The new couplings must
obey general cancellation conditions both at the dimension six and eight
levels, which result from expressing the operators obtained from the mediator
analysis in terms of a complete basis of operators. We illustrate with one
example how to apply this information to model building.


title: From F-theory GUTs to the LHC

abstract:
  This paper provides an overview to three recent papers on the bottom up
approach to GUTs in F-theory. We assume only a minimal familiarity with string
theory and phenomenology. After explaining the potential for predictive string
phenomenology within this framework, we introduce the ingredients of F-theory
GUTs, and show how these models naturally address various puzzles in
four-dimensional GUT models. We next describe how supersymmetry is broken, and
show that in a broad class of models, solving the mu/B mu problem requires a
specific scale of supersymmetry breaking consistent with a particular
deformation of the gauge mediation scenario. This rigid structure enables us to
reliably extract predictions for the sparticle spectrum of the MSSM. A brief
sketch of expected LHC signals, as well as ways to falsify this class of models
is also included.


title: The Supersymmetric Higgs

abstract:
  In the Minimal Supersymmetric Standard Model (the MSSM), the electroweak
symmetry is restored as supersymmetry-breaking terms are turned off. We
describe a generic extension of the MSSM where the electroweak symmetry is
broken in the supersymmetric limit. We call this limit the "sEWSB" phase, short
for supersymmetric electroweak symmetry breaking. We define this phase in an
effective field theory that only contains the MSSM degrees of freedom. The
sEWSB vacua naturally have an inverted scalar spectrum, where the heaviest
CP-even Higgs state has Standard Model-like couplings to the massive vector
bosons; experimental constraints in the scalar Higgs sector are more easily
satisfied than in the MSSM.


title: Scaling limit for a drainage network model

abstract:
  We consider the two dimensional version of a drainage network model
introduced by Gangopadhyay, Roy and Sarkar, and show that the appropriately
rescaled family of its paths converges in distribution to the Brownian web. We
do so by verifying the convergence criteria proposed by Fontes, Isopi, Newman
and Ravishankar.


title: Preheating after Multi-field Inflation

abstract:
  In this note I study preheating after multi-field inflation to assess the
feasibility of parametric resonance. An intuitive argument for the suppression
of resonances due to dephasing of fields in generic multi-field models is
presented. This effect is absent in effective single field models, rendering
them inappropriate for the study of preheating.


title:
Detection of the spin character of Fe(001) surface states by scanning
  tunneling microscopy: A theoretical proposal

abstract:
  We consider the magnetic structure on the Fe(001) surface and theoretically
study the scanning tunneling spectroscopy using a spin-polarized tip (SP-STM).
We show that minority-spin surface states induce a strong bias dependence of
the tunneling differential conductance which largely depends on the orientation
of the magnetization in the SP-STM tip relative to the easy magnetization axis
in the Fe(001) surface. We propose to use this effect in order to determine the
spin character of the Fe(001) surface states. This technique can be applied
also to other magnetic surfaces in which surface states are observed.


title:
Boundedness on inhomogeneous Lipschitz spaces of fractional integrals,
  singular integrals and hypersingular integrals associated to non-doubling
  measures

abstract:
  In the context of a finite measure metric space whose measure satisfies a
growth condition, we prove "T1" type necessary and sufficient conditions for
the boundedness of fractional integrals, singular integrals, and hypersingular
integrals on inhomogeneous Lipschitz spaces. We also indicate how the results
can be extended to the case of infinite measure. Finally we show applications
to Real and Complex Analysis.


title: A note on gaps

abstract:
  Let $p_{k}$ denote the $k$-th prime and $d(p_{k}) = p_{k} - p_{k - 1}$, the
difference between consecutive primes. We denote by $N_{\epsilon}(x)$ the
number of primes $\leq x$ which satisfy the inequality $d(p_{k}) \leq (\log
p_{k})^{2 + \epsilon}$, where $\epsilon > 0$ is arbitrary and fixed, and by
$\pi(x)$ the number of primes less than or equal to $x$. In this paper, we
first prove a theorem that $\lim_{x \to \infty} N_{\epsilon}(x)/\pi(x) = 1$. A
corollary to the proof of the theorem concerning gaps between consecutive
squarefree numbers is stated.


title: Angles as probabilities

abstract:
  We use a probabilistic interpretation of solid angles to generalize the
well-known fact that the inner angles of a triangle sum to 180 degrees. For the
3-dimensional case, we show that the sum of the solid inner vertex angles of a
tetrahedron T, divided by 2*pi, gives the probability that an orthogonal
projection of T onto a random 2-plane is a triangle. More generally, it is
shown that the sum of the (solid) inner vertex angles of an n-simplex S,
normalized by the area of the unit (n-1)-hemisphere, gives the probability that
an orthogonal projection of S onto a random hyperplane is an (n-1)-simplex.
Applications to more general polytopes are treated briefly, as is the related
Perles-Shephard proof of the classical Gram-Euler relations.


title: Multitransgression and regulators

abstract:
  In a parallel way to the work of Wang, we define higher order characteristic
classes associated with the Chern character, generalizing the work of
Bott-Chern and Gillet-Soul\'e on secondary characteristic classes. Our
formalism is simplicial and the computations are easier. As a consequence, we
obtain the comparison of Borel and Beilinson regulators and an explicit formula
for the real single-valued function associated with the Grasmannian
polylogarithm.


title: Field exposed water in a nanopore: liquid or vapour?

abstract:
  We study the behavior of ambient temperature water under the combined effects
of nanoscale confinement and applied electric field. Using molecular
simulations we analyze the thermodynamic causes of field-induced expansion at
some, and contraction at other conditions. Repulsion among parallel water
dipoles and mild weakening of interactions between partially aligned water
molecules prove sufficient to destabilize the aqueous liquid phase in isobaric
systems in which all water molecules are permanently exposed to a uniform
electric field. At the same time, simulations reveal comparatively weak
field-induced perturbations of water structure upheld by flexible hydrogen
bonding. In open systems with fixed chemical potential, these perturbations do
not suffice to offset attraction of water into the field; additional water is
typically driven from unperturbed bulk phase to the field-exposed region. In
contrast to recent theoretical predictions in the literature, our analysis and
simulations confirm that classical electrostriction characterizes usual
electrowetting behavior in nanoscale channels and nanoporous materials.


title: Dark energy perturbations and cosmic coincidence

abstract:
  While there is plentiful evidence in all fronts of experimental cosmology for
the existence of a non-vanishing dark energy (DE) density \rho_D in the
Universe, we are still far away from having a fundamental understanding of its
ultimate nature and of its current value, not even of the puzzling fact that
\rho_D is so close to the matter energy density \rho_M at the present time
(i.e. the so-called "cosmic coincidence" problem). The resolution of some of
these cosmic conundrums suggests that the DE must have some (mild) dynamical
behavior at the present time. In this paper, we examine some general properties
of the simultaneous set of matter and DE perturbations (\delta\rho_M,
\delta\rho_D) for a multicomponent DE fluid. Next we put these properties to
the test within the context of a non-trivial model of dynamical DE (the LXCDM
model) which has been previously studied in the literature. By requiring that
the coupled system of perturbation equations for \delta\rho_M and \delta\rho_D
has a smooth solution throughout the entire cosmological evolution, that the
matter power spectrum is consistent with the data on structure formation and
that the "coincidence ratio" r=\rho_D/\rho_M stays bounded and not unnaturally
high, we are able to determine a well-defined region of the parameter space
where the model can solve the cosmic coincidence problem in full compatibility
with all known cosmological data.


title: Convergence of symmetric trap models in the hypercube

abstract:
  We consider symmetric trap models in the d-dimensional hypercube whose
ordered mean waiting times, seen as weights of a measure in the natural
numbers, converge to a finite measure as d diverges, and show that the models
suitably represented converge to a K process as d diverges. We then apply this
result to get K processes as the scaling limits of the REM-like trap model and
the Random Hopping Times dynamics for the Random Energy Model in the hypercube
in time scales corresponding to the ergodic regime for these dynamics.


title: Dynamical Spin II

abstract:
  The possibility of building all particles from spinless constituents is
explored. Composite fermions are formed from bosonic carriers of electric and
magnetic charge of a composite abelian gauge field. Internal attributes are
accounted for by dimensional reduction from a higher-dimensional space-time in
which the abelian gauge field is replaced by a composite higher-rank
antisymmetric tensor field. The problem of building magnetically neutral
fermions is considered.


title:
Sersiclets - A Matched Filter Extension of Shapelets for Weak Lensing
  Studies

abstract:
  The precision study of dark matter using weak lensing by large scale
structure is strongly constrained by the accuracy with which one can measure
galaxy shapes. Several methods have been devised but none have demonstrated the
ability to reach the level of precision required by future weak lensing
surveys. In this Letter we explore new avenues to the existing Shapelets
approach, combining a priori knowledge of the galaxy profile with the power of
orthogonal basis function decomposition. This Letter discusses the new issues
raised by this matched filter approach and proposes promising alternatives to
shape measurement techniques. In particular it appears that the use of a
matched filter (e.g. Sersic profile) restricted to elliptical radial fitting
functions resolves several well known Shapelet issues.


title: Quantized detector network POVMs and the Franson-Bell experiment

abstract:
  We present a generalized POVM formalism for the calculation of quantum optics
networks of arbitrary complexity and apply it in a detailed analysis of the
Franson-Bell experiment. Our analysis suggests that when it comes to
observations of quantum processes, laboratory apparatus cannot always be used
according to classical principles.


title: Averaged large deviations for random walk in a random environment

abstract:
  In his 2003 paper, Varadhan proves the averaged large deviation principle for
the mean velocity of a particle taking a nearest-neighbor random walk in a
uniformly elliptic i.i.d. environment on $\mathbb{Z}^d$ with $d\geq1$, and
gives a variational formula for the corresponding rate function $I_a$. Under
Sznitman's transience condition (T), we show that $I_a$ is strictly convex and
analytic on a non-empty open set $\mathcal{A}$, and that the true velocity of
the particle is an element (resp. in the boundary) of $\mathcal{A}$ when the
walk is non-nestling (resp. nestling). We then identify the unique minimizer of
Varadhan's variational formula at any velocity in $\mathcal{A}$.


title:
Skull Flexure from Blast Waves: A Mechanism for Brain Injury with
  Implications for Helmet Design

abstract:
  Traumatic brain injury [TBI] has become a signature injury of current
military conflicts, with debilitating, costly, and long-lasting effects.
Although mechanisms by which head impacts cause TBI have been well-researched,
the mechanisms by which blasts cause TBI are not understood. From numerical
hydrodynamic simulations, we have discovered that non-lethal blasts can induce
sufficient skull flexure to generate potentially damaging loads in the brain,
even without a head impact. The possibility that this mechanism may contribute
to TBI has implications for injury diagnosis and armor design.


title: Expressions for Catalan Kronecker Products

abstract:
  We give some elementary manifestly positive formulae for the Kronecker
products s_(d,d) * s_(d+k,d-k) and s_(d,d) * s_(2d-k,1^k). These formulae
demonstrate some fundamental properties of the Kronecker coefficients, and we
use them to deduce a number of enumerative and combinatorial results.


title: Double Hall algebras and derived equivalences

abstract:
  We show that the reduced Drinfeld double of the Ringel-Hall algebra of a
hereditary category is invariant under derived equivalences. By associating an
explicit isomorphism to a given derived equivalence, we also extend the results
of [BS1], [BS2], [SVdB], and [XY].


title: Global rough solutions to the cubic nonlinear Boussinesq equation

abstract:
  We prove that the initial value problem (IVP) for the cubic defocusing
nonlinear Boussinesq equation $u_{tt}-u_{xx}+u_{xxxx}-(|u|^2u)_{xx}=0$ on the
real line is globally well-posed in $H^{s}(\R)$ provided $2/3<s<1$.


title: Dynamics of Asymptotically Hyperbolic Manifolds

abstract:
  We prove a dynamical wave trace formula for asymptotically hyperbolic (n+1)
dimensional manifolds with negative (but not necessarily constant) sectional
curvatures which equates the renormalized wave trace to the lengths of closed
geodesics. A corollary of this dynamical trace formula is a dynamical
resonance-wave trace formula for compact perturbations of convex co-compact
hyperbolic manifolds which we use to prove a growth estimate for the length
spectrum counting function. We next define a dynamical zeta function and prove
its analyticity in a half plane. In our main result, we produce a prime orbit
theorem for the geodesic flow. This is the first such result for manifolds
which have neither constant curvature nor finite volume. As a corollary to the
prime orbit theorem, using our dynamical resonance-wave trace formula, we show
that the existence of pure point spectrum for the Laplacian on negatively
curved compact perturbations of convex co-compact hyperbolic manifolds is
related to the dynamics of the geodesic flow.


title: Chemistry in Disks. II. -- Poor molecular content of the AB Aur disk

abstract:
  We study the molecular content and chemistry of a circumstellar disk
surrounding the Herbig Ae star AB Aur at (sub-)millimeter wavelengths. Our aim
is to reconstruct the chemical history and composition of the AB Aur disk and
to compare it with disks around low-mass, cooler T Tauri stars. We observe the
AB Aur disk with the IRAM Plateau de Bure Interferometer in the C- and D-
configurations in rotational lines of CS, HCN, C2H, CH3OH, HCO+, and CO
isotopes. Using an iterative minimization technique, observed columns densities
and abundances are derived. These values are further compared with results of
an advanced chemical model that is based on a steady-state flared disk
structure with a vertical temperature gradient, and gas-grain chemical network
with surface reactions. We firmly detect HCO+ in the 1--0 transition,
tentatively detect HCN, and do not detect CS, C2H, and CH3OH. The observed HCO+
and 13CO column densities as well as the upper limits to the column densities
of HCN, CS, C2H, and CH3OH are in good agreement with modeling results and
those from previous studies. The AB Aur disk possesses more CO, but is less
abundant in other molecular species compared to the DM Tau disk. This is
primarily caused by intense UV irradiation from the central Herbig A0 star,
which results in a hotter disk where CO freeze out does not occur and thus
surface formation of complex CO-bearing molecules might be inhibited.


title: Quantum Impurity Problems in Condensed Matter Physics

abstract:
  Impurities are ubiquitous in condensed matter. Boundary Conformal Field
Theory (BCFT) provides a powerful method to study a localized quantum impurity
interacting with a gapless continuum of excitations. The results can also be
implied to nanoscopic devices like quantum dots. In these lecture notes, I
review this field, including the following topics: I. General Renormalization
Group (RG) framework for quantum impurity problems: example of simplest Kondo
model II. Multi-channel Kondo model III. Quantum Dots: experimental
realizations of one and two channel Kondo models IV. Impurities in Luttinger
liquids: point contact in a quantum wire V. Quantum impurity entanglement
entropy VI. Y-junctions of Luttinger liquids VII. Boundary condition changing
operators and the X-ray edge problem.


title: Electrically Driven Light Emission from Individual CdSe Nanowires

abstract:
  We report electroluminescence (EL) measurements carried out on three-terminal
devices incorporating individual n-type CdSe nanowires. Simultaneous optical
and electrical measurements reveal that EL occurs near the contact between the
nanowire and a positively biased electrode or drain. The surface potential
profile, obtained by using Kelvin probe microscopy, shows an abrupt potential
drop near the position of the EL spot, while the band profile obtained from
scanning photocurrent microscopy indicates the existence of an n-type Schottky
barrier at the interface. These observations indicate that light emission
occurs through a hole leakage or an inelastic scattering induced by the rapid
potential drop at the nanowire-electrode interface.


title: On inequivalent factorizations of a cycle

abstract:
  We introduce a bijection between inequivalent minimal factorizations of the
n-cycle (1 2 ... n) into a product of smaller cycles of given length, on one
side, and trees of a certain structure on the other. We use this bijection to
count the factorizations with a given number of different commuting factors
that can appear in the first and in the last positions, a problem which has
found applications in physics. We also provide a necessary and sufficient
condition for a set of cycles to be arrangeable into a product evaluating to (1
2 ... n).