title:
Exploiting the nonlinear impact dynamics of a single-electron shuttle
  for highly regular current transport

abstract:
  The nanomechanical single-electron shuttle is a resonant system in which a
suspended metallic island oscillates between and impacts at two electrodes.
This setup holds promise for one-by-one electron transport and the
establishment of an absolute current standard. While the charge transported per
oscillation by the nanoscale island will be quantized in the Coulomb blockade
regime, the frequency of such a shuttle depends sensitively on many parameters,
leading to drift and noise. Instead of considering the nonlinearities
introduced by the impact events as a nuisance, here we propose to exploit the
resulting nonlinear dynamics to realize a highly precise oscillation frequency
via synchronization of the shuttle self-oscillations to an external signal.


title: Quantum Measurements Are Noncontextual

abstract:
  Quantum measurements are noncontextual, with outcomes independent of which
other commuting observables are measured at the same time, when consistently
analyzed using principles of Hilbert space quantum mechanics rather than
classical hidden variables.


title:
Parabolic Littlewood-Paley inequality for $\phi(-\Delta)$-type operators
  and applications to Stochastic integro-differential equations

abstract:
  In this paper we prove a parabolic version of the Littlewood-Paley inequality
for the operators of the type $\phi(-\Delta)$, where $\phi$ is a Bernstein
function. As an application, we construct an $L_p$-theory for the stochastic
integro-differential equations of the type $du=(-\phi(-\Delta)u+f)dt +gdW_t$.


title: Irreducible Components of the Nilpotent Cone of the Tadpole Quiver

abstract:
  We exhibit the irreducible components of the nilpotent cone of the tadpole
quiver of arbitrarily high codimension and introduce an approach that could
allow to describe all of them.


title:
Resting-State Functional Connectivity in Late-Life Depression: Higher
  Global Connectivity and More Long Distance Connections

abstract:
  Functional magnetic resonance imaging recordings in the resting-state (RS)
from the human brain are characterized by spontaneous low-frequency
fluctuations in the blood oxygenation level dependent signal that reveal
functional connectivity (FC) via their spatial synchronicity. This RS study
applied network analysis to compare FC between late-life depression (LLD)
patients and control subjects. Raw cross-correlation matrices (CM) for LLD were
characterized by higher FC. We analyzed the small-world (SW) and modular
organization of these networks consisting of 110 nodes each as well as the
connectivity patterns of individual nodes of the basal ganglia. Topological
network measures showed no significant differences between groups. The
composition of top hubs was similar between LLD and control subjects, however
in the LLD group posterior medial-parietal regions were more highly connected
compared to controls. In LLD, a number of brain regions showed connections with
more distant neighbors leading to an increase of the average Euclidean distance
between connected regions compared to controls. In addition, right caudate
nucleus connectivity was more diffuse in LLD. In summary, LLD was associated
with overall increased FC strength and changes in the average distance between
connected nodes, but did not lead to global changes in SW or modular
organization.


title: Pooling-Invariant Image Feature Learning

abstract:
  Unsupervised dictionary learning has been a key component in state-of-the-art
computer vision recognition architectures. While highly effective methods exist
for patch-based dictionary learning, these methods may learn redundant features
after the pooling stage in a given early vision architecture. In this paper, we
offer a novel dictionary learning scheme to efficiently take into account the
invariance of learned features after the spatial pooling stage. The algorithm
is built on simple clustering, and thus enjoys efficiency and scalability. We
discuss the underlying mechanism that justifies the use of clustering
algorithms, and empirically show that the algorithm finds better dictionaries
than patch-based methods with the same dictionary size.


title:
Absence of strong magnetic fluctuations in the iron phosphide
  superconductors LaFePO and Sr2ScO3FeP

abstract:
  We report neutron inelastic scattering measurements on polycrystalline LaFePO
and Sr2ScO3FeP, two members of the iron phosphide families of superconductors.
No evidence is found for any magnetic fluctuations in the spectrum of either
material in the energy and wavevector ranges probed. Special attention is paid
to the wavevector at which spin-density-wave-like fluctuations are seen in
other iron-based superconductors. We estimate that the magnetic signal, if
present, is at least a factor of four (Sr2ScO3FeP) or seven (LaFePO) smaller
than in the related iron arsenide and chalcogenide superconductors. These
results suggest that magnetic fluctuations are not as influential on the
electronic properties of the iron phosphide systems as they are in other
iron-based superconductors.


title:
Measurement of D^\pm production in deep inelastic ep scattering with the
  ZEUS detector at HERA

abstract:
  Charm production in deep inelastic ep scattering was measured with the ZEUS
detector using an integrated luminosity of 354 pb^{-1}. Charm quarks were
identified by reconstructing D^{+} mesons in the D^{+} -> K^{-} pi^{+} pi^{+}
decay channel. Lifetime information was used to reduce combinatorial background
substantially. Differential cross sections were measured in the kinematic
region 5 < Q^{2} < 1000 GeV^{2}, 0.02 < y < 0.7, 1.5 < p_{T}(D^{+}) < 15 GeV
and |eta(D^{+})| < 1.6, where Q^{2} is the photon virtuality, y is the
inelasticity, and p_{T}(D^{+}) and eta(D^{+}) are the transverse momentum and
the pseudorapidity of the D^{+} meson, respectively. Next-to-leading-order QCD
predictions are compared to the data. The charm contribution, F_{2}^{cc}, to
the proton structure-function F_{2} was extracted.


title:
Manifestation of the magnetic moments of Cooper pairs in low-temperature
  properties of superconducting thin-film rings

abstract:
  Experimental determination of the magnetic moment of the Cooper pairs can
shed light on the pairing symmetry in cuprates. We argue that the intrinsic
magnetic moments of the Cooper pairs can be detected in experiments with
superconducting thin-film rings. At sufficiently low temperatures the magnetic
field generated by the supercurrent, can cause the ordering of these magnetic
moments that produces changes in the supercurrent and magnetic induction
distributions, the heat capacity and magnetic moment of the ring. It is shown
that the intrinsic magnetic moment of the Cooper pairs can be extracted from
low-temperature behaviours of these measurable quantities of the
current-carrying rings made of the cuprate superconductors.


title: Fermionic Corrections to Fluid Dynamics from BTZ Black Hole

abstract:
  We reconstruct the complete fermionic orbit of the non-extremal BTZ black
hole by acting with finite supersymmetry transformations. The solution
satisfies the exact supergravity equations of motion to all orders in the
fermonic expansion and the final result is given in terms of fermionic
bilinears. By fluid/gravity correspondence, we derive linearized Navier-Stokes
equations and a set of new differential equations from Rarita-Schwinger
equation. We compute the boundary energy-momentum tensor and we interpret the
result as a perfect fluid with a modified definition of fluid velocity.
Finally, we derive the modified expression for the entropy of the black hole in
terms of the fermionic bilinears.


title: Controlling colloidal phase transitions with critical Casimir forces

abstract:
  The critical Casimir effect provides a thermodynamic analogue of the
well-known quantum mechanical Casimir effect. It acts between two surfaces
immersed in a critical binary liquid mixture, and results from the confinement
of concentration fluctuations of the solvent. Unlike the quantum mechanical
effect, the magnitude and range of this attraction can be adjusted with
temperature via the solvent correlation length, thus offering new opportunities
for the assembly of nano and micron-scale structures. Here, we demonstrate the
active assembly control of equilibrium phases using critical Casimir forces. We
guide colloidal particles into analogues of molecular liquid and solid phases
via exquisite control over their interactions. By measuring the critical
Casimir particle pair potential directly from density fluctuations in the
colloidal gas, we obtain insight into liquefaction at small scales: We apply
the Van der Waals model of molecular liquefaction and show that the colloidal
gas-liquid condensation is accurately described by the Van der Waals theory,
even on the scale of a few particles. These results open up new possibilities
in the active assembly control of micro and nanostructures.


title: P3: Toward Privacy-Preserving Photo Sharing

abstract:
  With increasing use of mobile devices, photo sharing services are
experiencing greater popularity. Aside from providing storage, photo sharing
services enable bandwidth-efficient downloads to mobile devices by performing
server-side image transformations (resizing, cropping). On the flip side, photo
sharing services have raised privacy concerns such as leakage of photos to
unauthorized viewers and the use of algorithmic recognition technologies by
providers. To address these concerns, we propose a privacy-preserving photo
encoding algorithm that extracts and encrypts a small, but significant,
component of the photo, while preserving the remainder in a public,
standards-compatible, part. These two components can be separately stored. This
technique significantly reduces the signal-to-noise ratio and the accuracy of
automated detection and recognition on the public part, while preserving the
ability of the provider to perform server-side transformations to conserve
download bandwidth usage. Our prototype privacy-preserving photo sharing
system, P3, works with Facebook, and can be extended to other services as well.
P3 requires no changes to existing services or mobile application software, and
adds minimal photo storage overhead.


title:
Concentration on Surfaces for a Singularly Perturbed Neumann Problem in
  Three-Dimensional Domains

abstract:
  We consider the following singularly perturbed elliptic problem $$
\varepsilon^2\triangle\tilde{u}-\tilde{u}+\tilde{u}^p=0, \ \tilde{u}>0\quad
\mbox{in} \ \Omega,\ \ \ \frac{\partial\tilde{u}}{\partial \mathbf{n}}=0 \quad
\mbox{on}\ \partial\Omega, $$ where $\Omega$ is a bounded domain in
$\mathbb{R}^3$ with smooth boundary, $\varepsilon$ is a small parameter,
$\mathbf{n}$ denotes the inward normal of $ \partial\Omega$ and the exponent
$p>1$. Let $\Gamma$ be a hypersurface intersecting $\partial\Omega$ in the
right angle along its boundary $\partial\Gamma$ and satisfying a {\em
non-degenerate condition}. We establish the existence of a solution
$u_\varepsilon$ concentrating along a surface $\tilde{\Gamma}$ close to
$\Gamma$, exponentially small in $\varepsilon$ at any positive distance from
the surface $\tilde{\Gamma}$, provided $\varepsilon$ is small and away from
certain {\em critical numbers}. The concentrating surface $\tilde{\Gamma}$ will
collapse to $\Gamma$ as $\varepsilon\rightarrow 0$.


title: Non stationary nucleation: the model with averaged velocity

abstract:
  A new model to calculate the rate of nucleation is formulated. This model is
based on the classical nucleation theory but considers also vapor depletion
around the formed embryo. The key characteristic which arises in frames of this
theory is the mean time of the embryo formation. On the base of this time the
probability to observe the embryo formed during the given time is estimated
which allows to construct a simple approximate theory.


title:
The 1D Heisenberg antiferromagnet model by the variation after
  projection method

abstract:
  The 4 sites and 8 sites 1D anti-ferromagnetic Heisenberg chains in the
Jordan-Wigner representation are investigated within the standard Hartree-Fock
and RPA approaches, both in the symmetry unbroken and in the symmetry broken
phases. A translation invariant groundstate, obtained by the projection method
as a linear combination of a symmetry-broken HF state and its image under
reflection, is also considered, for each chain type. It is found that the
projection method considerably improves the HF treatment for instance as far as
the groundstate energy is concerned, but also with respect to the RPA energies.
The results are furthermore confronted with the ones obtained within so-called
SCRPA scheme.


title: Anisotropy and superconductivity

abstract:
  The mean field method is applied for analysis of valence electrons in metals.
It is shown that at low temperatures electrons have two wave-vector
distribution patterns. Isotropic distribution refers to the first pattern.
Anisotropic distribution refers to another pattern, particularly to specific
wave-vector values occurred nearby the Fermi sphere. It is shown that it is the
anisotropy that makes the metal obtain its specific superconductor features.


title: Pair correlation of hyperbolic lattice angles

abstract:
  Let $\omega$ be a point in the upper half plane, and let $\Gamma$ be a
discrete, finite covolume subgroup of $\mathrm{PSL}_2(\mathbb{R})$. We
conjecture an explicit formula for the pair correlation of the angles between
geodesic rays of the lattice $\Gamma\omega$, intersected with increasingly
large balls centered at $\omega$. We prove this conjecture for
$\Gamma=\mathrm{PSL}_2(\mathbb{Z})$ and $\omega$ an elliptic point.


title:
Multiplet effects in orbital and spin ordering phenomena: A
  hybridization-expansion quantum impurity solver study

abstract:
  Orbital and spin ordering phenomena in strongly correlated systems are
commonly studied using the local-density approximation + dynamical mean-field
theory approach. Typically, however, such simulations are restricted to
simplified models (density-density Coulomb interactions, high symmetry
couplings and few-band models). In this work we implement an efficient general
hybridization-expansion continuous-time quantum Monte Carlo impurity solver
(Krylov approach) which allows us to investigate orbital and spin ordering in a
more realistic setting, including interactions that are often neglected (e.g.,
spin-flip and pair-hopping terms), enlarged basis sets (full d versus eg),
low-symmetry distortions, and reaching the very low-temperature (experimental)
regime. We use this solver to study ordering phenomena in a selection of
exemplary low-symmetry transition-metal oxides: LaMnO3 and rare-earth
manganites as well as the perovskites CaVO3 and YTiO3. We show that spin-flip
and pair hopping terms do not affect the Kugel-Khomskii orbital-order melting
transition in rare-earth manganites, or the suppression of orbital fluctuations
driven by crystal field and Coulomb repulsion. For the Mott insulator YTiO3 we
find a ferromagnetic transition temperature 50 K, in remarkably good agreement
with experiments. For LaMnO3 we show that the classical t2g-spin approximation,
commonly adopted for studying manganites, yields indeed an occupied eg orbital
in very good agreement with that obtained for the full d 5-orbital Hubbard
model, while the spin-spin e_g-t_{2g} correlation function calculated from the
full d model is 0.74, very close to the value expected for aligned eg and t2g
spins; the eg spectral function matrix is also well reproduced. Finally, we
show that the t2g screening reduces the eg-eg Coulomb repulsion by about 10%


title: Quantum speed limit for non-Markovian dynamics

abstract:
  We derive a Margolus-Levitin type bound on the minimal evolution time of an
arbitrarily driven open quantum system. We express this quantum speed limit
time in terms of the operator norm of the nonunitary generator of the dynamics.
We apply these results to the damped Jaynes-Cummings model and demonstrate that
the corresponding bound is tight. We further show that non-Markovian effects
can speed up quantum evolution and therefore lead to a smaller quantum speed
limit time.


title:
Exploring the foundations of quantum mechanics using Monte Carlo
  simulations of the Freedman-Clauser experimental test of Bell's Inequality

abstract:
  Monte Carlo simulations of the Freedman-Clauser experiment are used to test
the generic wave function collapse model of Quantum Mechanics, a local
realistic model, and a dynamical state reduction model of wave function
collapse. The simulated results are compared to the actual results of the
experiment which confirmed the quantum mechanical calculation for nine
different relative angles between the two polarization analyzers. For each
simulation $5\times10^7$ total simulated photon pairs were generated at each
relative angle. The generic wave function collapse model closely followed the
general shape of the theoretical calculation but differed from the calculated
values by 2.5% to 3.3% for angles less than or equal to $\pi/8$ and differed by
15.0% to 52.5% for angles greater than or equal to $3\pi/8$. The local
realistic model did not replicate the experimental results but was generally
within 1% of a classical calculation for all analyzer angles. A dynamical state
reduction/collapse model, approximated by using a "smeared" polarization,
yielded values within 1% of the quantum mechanical calculation and provides an
independent estimate of the correlation length used in these models of $r_c =
(1.04 \pm 0.14)\times 10^{-5}$ cm.


title: The geometry of barotropic flow

abstract:
  In this article we write the equations of barotropic compressible fluid
mechanics as a geodesic equation on an infinite-dimensional manifold. The
equations are given by \begin{align} u_t + \nabla_uu = -\frac{1}{\rho} \grad p
\\ \rho_t + \diver{(\rho u)} = 0, \end{align} where the fluid fills up a
compact manifold $M$, $u$ is a time-dependent velocity field on $M$, and $\rho$
is the density, a positive function on $M$. The barotropic assumption is that
the pressure $p$ is some given function of the density, although our methods
also extend to certain more general isentropic flows. Our infinite-dimensional
manifold is the product $\mathcal{D}(M)\times C^{\infty}(M,\mathbb{R})$. This
is a group using the semidirect product (which is sometimes incorporated in
other treatments), but the Riemannian metric we use is neither left- nor
right-invariant. Hence our geodesic equation is \emph{not} an Euler-Arnold
equation. We compute the sectional curvature and show that at least when
$M=S^1$, the curvature is always nonnegative. We also establish some results on
the Lagrangian linear stability of solutions of this system, for certain
nonsteady solutions in one dimension and steady solutions in two dimensions.


title:
Double Greedy Algorithms: Reduced Basis Methods for Transport Dominated
  Problems

abstract:
  The central objective of this paper is to develop reduced basis methods for
parameter dependent transport dominated problems that are rigorously proven to
exhibit rate-optimal performance when compared with the Kolmogorov $n$-widths
of the solution sets. The central ingredient is the construction of
computationally feasible "tight" surrogates which in turn are based on deriving
a suitable well-conditioned variational formulation for the parameter dependent
problem. The theoretical results are illustrated by numerical experiments for
convection-diffusion and pure transport equations. In particular, the latter
example sheds some light on the smoothness of the dependence of the solutions
on the parameters.


title:
On the existence of solutions to nonlinear systems of higher order
  Poisson type

abstract:
  In this paper, we study the existence of higher order Poisson type systems.
In detail, we prove a Residue type phenomenon for the fundamental solution of
Laplacian in $\RR^n, n\ge 3$. This is analogous to the Residue theorem for the
Cauchy kernel in $\CC$. With the aid of the Residue type formula for the
fundamental solution, we derive the higher order derivative formula for the
Newtonian potential and obtain its appropriate $\s C^{k, \alpha}$ estimates.
The existence of solutions to higher order Poisson type nonlinear systems is
concluded as an application of the fixed point theorem.


title:
Pulsed laser deposition with simultaneous in situ real-time monitoring
  of optical spectroscopic ellipsometry and reflection high-energy electron
  diffraction

abstract:
  We present a pulsed laser deposition (PLD) system that can monitor growth by
simultaneously using in situ optical spectroscopic ellipsometry (SE) and
reflection high-energy electron diffraction (RHEED). The RHEED precisely
monitors the number of thin-film layers and surface structure during the
deposition and the SE measures the optical spectra of the samples
simultaneously. The thin-film thickness information obtained from RHEED
facilitates the SE modeling process, which allows extracting the in situ
optical spectra, i.e. the dielectric functions, of thin-films during growth.
The in situ dielectric functions contain indispensable information about the
electronic structure of thin-films. We demonstrate the performance of this
system by growing LaMnO3+{\delta} (LMO) thin-films on SrTiO3 (001) substrates.
By using in situ SE and RHEED simultaneously, we show that real-time thickness
and dielectric functions of the LMO thin-films can be effectively extracted.
The simultaneous monitoring of both optical SE and RHEED offers important clues
to understand the growth mechanism of atomic-scale thin-films.

categories: cond-mat.mtrl-sci cond-mat.mes-hall cond-mat.str-el cond-mat.supr-con


title: Riemannian geometry on the quantomorphism group

abstract:
  We are interested in the geometry of the group $\mathcal{D}_q(M)$ of
diffeomorphisms preserving a contact form $\theta$ on a manifold $M$. We define
a Riemannian metric on $\mathcal{D}_q(M)$, compute the corresponding geodesic
equation, and show that solutions exist for all time and depend smoothly on
initial conditions. In certain special cases (such as on the 3-sphere), the
geodesic equation is a simplified version of the quasigeostrophic equation, so
we obtain a new geodesic interpretation of this geophysical system. We also
show that the genuine quasigeostrophic equation on $S^2$ can be obtained as an
Euler-Arnold equation on a one-dimensional central extension of
$T_{\id}\mathcal{D}_q(M)$, and that our global existence result extends to this
case.
  If $E$ is the Reeb field of $\theta$ and $\mu$ is the volume form, assumed
compatible in the sense that $\text{div} E=0$, we show that $\mathcal{D}_q(M)$
is a smooth submanifold of $\mathcal{D}_{E,\mu}(M)$, the space of
diffeomorphisms preserving the vector field $E$ and the volume form $\mu$, in
the sense of $H^s$ Sobolev completions. The latter manifold is related to
symmetric motion of ideal fluids. We further prove that the corresponding
geodesic equations and projections are $C^{\infty}$ objects in the Sobolev
topology.


title:
Property A and the existence of a Markov process with a trivial Poisson
  boundary

abstract:
  This note make the observation that property A for a space is equivalent to
the existence of a Markov process on the space which has a (uniformly) trivial
Poisson boundary.


title: Ordered amorphous spin system

abstract:
  A solid is typically deemed amorphous when there are no Bragg peaks in its
diffraction pattern. We discuss a two dimensional configuration of Ising spins
with an autocorrelation function which vanishes at all nonzero distances, so
that its scattering pattern is flat. This configuration is a ground state of a
Hamiltonian with deterministic, translationally-invariant and finite range
interactions. Despite ostensibly being amorphous, this configuration has
perfect underlying order. The finite temperature behavior of this model
exhibits ordering transitions at successively larger length scales.


title: Dependence spaces II

abstract:
  We introduce the concept of Exchange of Independent Sets (EIS) property for
spaces. We show that in a dependence spaces the EIS property holds.


title:
Extremal Myers-Perry black holes coupled to Born-Infeld electrodynamics
  in five dimensions

abstract:
  We construct a new class of perturbative extremal charged rotating black hole
solutions in five dimensions in the Einstein--Born-Infeld theory. We start with
an extremal five-dimensional Myers-Perry black hole seed in which the two
possible angular momenta have equal magnitude, and add Born-Infeld electrical
charge keeping the extremality condition as a constraint. The perturbative
parameter is assumed to be the electric charge $q$ and the perturbations are
performed up to 4th order. We also study some physical properties of these
black holes. It is shown that the perturbative parameter $q$ and the
Born-Infeld parameter $\beta$ modify the values of the physical quantities of
the black holes. The solution suggests that the magnetic moment and
gyromagnetic ratio of the black hole spacetime change sign when the Born-Infeld
character of the solution starts to depart strongly from the Maxwell limit. We
venture an interpretation for the effect.


title: Isobaric analog states in the f_{7/2} and g_{9/2} shells

abstract:
  Calculations are performed for energies of isobaric analog states with
isospins T=2 and T=3 in regions where they have been found experimentally e.g.
f-p shell, and regions where they have not yet been found e.g. g_{9/2} near
Z=50,N=50. We consider two approaches--one using binding energy formulas and
Coulomb energies contained therein and the other using shell model
calculations. It is noted that some (but not all) calculations yield very low
excitation energies for the J=0^{+} T=2 isobaric analog state in ^{96} Ag.


title: Quantum error correction via less noisy qubits

abstract:
  Known quantum error correction schemes are typically able to take advantage
of only a limited class of classical error-correcting codes.
Entanglement-assisted quantum error correction is a partial solution which made
it possible to exploit any classical linear codes over the binary or quaternary
finite field. However, the known entanglement-assisted scheme requires
noiseless qubits that help correct quantum errors on noisy qubits, which can be
too severe an assumption. We prove that a more relaxed and realistic assumption
is sufficient by presenting encoding and decoding operations assisted by qubits
on which quantum errors of one particular kind may occur. As in entanglement
assistance, our scheme can import any binary or quaternary linear codes. If the
auxiliarly qubits are noiseless, our codes become entanglement-assisted codes,
and saturate the quantum Singleton bound when the underlying classical codes
are maximum distance separable.


title:
Proceedings of the Third International Workshop on Domain-Specific
  Languages and Models for Robotic Systems (DSLRob 2012)

abstract:
  Proceedings of the Third International Workshop on Domain-Specific Languages
and Models for Robotic Systems (DSLRob'12), held at the 2012 International
Conference on Simulation, Modeling, and Programming for Autonomous Robots
(SIMPAR 2012), November 2012 in Tsukuba, Japan.
  The main topics of the workshop were Domain-Specific Languages (DSLs) and
Model-driven Architecture (MDA) for robotics. A domain-specific language (DSL)
is a programming language dedicated to a particular problem domain that offers
specific notations and abstractions that increase programmer productivity
within that domain. Models-driven architecture (MDA) offers a high-level way
for domain users to specify the functionality of their system at the right
level of abstraction. DSLs and models have historically been used for
programming complex systems. However recently they have garnered interest as a
separate field of study. Robotic systems blend hardware and software in a
holistic way that intrinsically raises many crosscutting concerns (concurrency,
uncertainty, time constraints, ...), for which reason, traditional
general-purpose languages often lead to a poor fit between the language
features and the implementation requirements. DSLs and models offer a powerful,
systematic way to overcome this problem, enabling the programmer to quickly and
precisely implement novel software solutions to complex problems within the
robotics domain.


title: Hydrodynamic description of Hard-core Bosons on a Galileo ramp

abstract:
  We study the quantum evolution of a cloud of hard-core bosons loaded on a
one-dimensional optical lattice after its sudden release from a harmonic trap.
Just after the trap has been removed, a linear ramp potential is applied,
mimicking the so called Galileo ramp experiment. The non-equilibrium expansion
of the bosonic cloud is elucidated through a hydrodynamical description which
is compared to the exact numerical evolution obtained by exact diagonalization
on finite lattice sizes. The system is found to exhibit a rich behavior showing
in particular Bloch oscillations of a self-trapped condensate and an ejected
particle density leading to two diverging entangled condensates. Depending on
the initial density of the gas different regimes of Josephson-like oscillations
are observed. At low densities, the trapped part of the cloud is in a
superfluid phase that oscillates in time as a whole. At higher densities, the
trapped condensate is in a mixed superfluid-Mott phase that show a breathing
regime for steep enough potential ramps.


title: Orbital Phase Variations of the Eccentric Giant Planet HAT-P-2b

abstract:
  We present the first secondary eclipse and phase curve observations for the
highly eccentric hot Jupiter HAT-P-2b in the 3.6, 4.5, 5.8, and 8.0 \mu m bands
of the Spitzer Space Telescope. The 3.6 and 4.5 \mu m data sets span an entire
orbital period of HAT-P-2b, making them the longest continuous phase curve
observations obtained to date and the first full-orbit observations of a planet
with an eccentricity exceeding 0.2. We present an improved non-parametric
method for removing the intrapixel sensitivity variations in Spitzer data at
3.6 and 4.5 \mu m that robustly maps position-dependent flux variations. We
find that the peak in planetary flux occurs at 4.39+/-0.28, 5.84+/-0.39, and
4.68+/-0.37 hours after periapse passage with corresponding maxima in the
planet/star flux ratio of 0.1138%+/-0.0089%, 0.1162%+/-0.0080%, and
0.1888%+/-0.0072% in the 3.6, 4.5, and 8.0 \mu m bands respectively. We compare
our measured secondary eclipse depths to the predictions from a one-dimensional
radiative transfer model, which suggests the possible presence of a transient
day side inversion in HAT-P-2b's atmosphere near periapse. We also derive
improved estimates for the system parameters, including its mass, radius, and
orbital ephemeris. Our simultaneous fit to the transit, secondary eclipse, and
radial velocity data allows us to determine the eccentricity and argument of
periapse of HAT-P-2b's orbit with a greater precision than has been achieved
for any other eccentric extrasolar planet. We also find evidence for a
long-term linear trend in the radial velocity data. This trend suggests the
presence of another substellar companion in the HAT-P-2 system, which could
have caused HAT-P-2b to migrate inward to its present-day orbit via the Kozai
mechanism.


title:
Model-driven engineering approach to design and implementation of robot
  control system

abstract:
  In this paper we apply a model-driven engineering approach to designing
domain-specific solutions for robot control system development. We present a
case study of the complete process, including identification of the domain
meta-model, graphical notation definition and source code generation for
subsumption architecture -- a well-known example of robot control architecture.
Our goal is to show that both the definition of the robot-control architecture
and its supporting tools fits well into the typical workflow of model-driven
engineering development.


title: Cluster Cosmology at a Crossroads: Neutrino Masses

abstract:
  Galaxy clusters --- in combination with CMB and BAO data --- can provide
precise constraints on the sum of neutrino masses. However, these constraints
depend on the calibration of the mass--observable relation. For instance, the
mass calibration employed in Planck Collaboration (2011a,b) rules out the
minimal 6-parameter \Lambda CDM model at 3.7\sigma, and implies a sum of
neutrino masses \sum m_\nu = 0.39 \pm 0.10. By contrast, the mass calibration
favored by Rozo et al. (2012b) from a self-consistent analysis of X-ray, SZ,
and optical scaling relations is consistent with a minimal flat \Lambda CDM
model with no massive neutrinos (1.7\sigma), and is a better fit to additional
data (e.g. H0). We discuss these results in light of the recent SPT and ACT
analysis, noting that the Rozo et al. (2012b) model suggests the current mild
"tension" (<2\sigma) between CMB and BAO+H_0 data will decrease as the
uncertainties in these measurements decrease.


title:
Missing data outside the detector range: application to continuous
  variable entanglement verification and quantum cryptography

abstract:
  In continuous-variable quantum information processing detectors are
necessarily coarse grained and of finite range. We discuss how especially the
latter feature is a bug and may easily lead to overoptimistic estimates of
entanglement and of security, when missed data outside the detector range are
ignored. We show that entropic separability or security criteria are much
superior to variance-based criteria for mitigating the negative effects of this
bug.


title: Indicators of Mass in Spherical Stellar Atmospheres

abstract:
  Mass is the most important stellar parameter, but it is not directly
observable for a single star. Spherical model stellar atmospheres are
explicitly characterized by their luminosity ($L_\star$), mass ($M_\star$) and
radius ($R_\star$), and observations can now determine directly $L_\star$ and
$R_\star$. We computed spherical model atmospheres for red giants and for red
supergiants holding $L_\star$ and $R_\star$ constant at characteristic values
for each type of star but varying $M_\star$, and we searched the predicted flux
spectra and surface-brightness distributions for features that changed with
mass. For both stellar classes we found similar signatures of the star's mass
in both the surface-brightness distribution and the flux spectrum. The spectral
features have been use previously to determine $\log_{10} (g)$, and now that
the luminosity and radius of a non-binary red giant or red supergiant can be
observed, spherical model stellar atmospheres can be used to determine the
star's mass from currently achievable spectroscopy. The surface-brightness
variations with mass are slightly smaller than can be resolved by current
stellar imaging, but they offer the advantage of being less sensitive to the
detailed chemical composition of the atmosphere.


title:
A Reconstruction Theorem for Quantum Cohomology of Fano Bundles on
  Projective Space

abstract:
  We present a reconstruction theorem for Fano vector bundles on projective
space which recovers the small quantum cohomology for the projectivisation of
the bundle from a small number of low-degree Gromov--Witten invariants. We
provide an extended example in which we calculate the quantum cohomology of a
certain Fano 9-fold and deduce from this, using the quantum Lefschetz theorem,
the quantum period sequence for a Fano 3-fold of Picard rank 2 and degree 24.
This example is new, and is important for the Fanosearch programme.


title: On regular hypergraphs of high girth

abstract:
  We give lower bounds on the maximum possible girth of an $r$-uniform,
$d$-regular hypergraph with at most $n$ vertices, using the definition of a
hypergraph cycle due to Berge. These differ from the trivial upper bound by an
absolute constant factor (viz., by a factor of between $3/2+o(1)$ and $2
+o(1)$). We also define a random $r$-uniform `Cayley' hypergraph on $S_n$ which
has girth $\Omega (n^{1/3})$ with high probability, in contrast to random
regular $r$-uniform hypergraphs, which have constant girth with positive
probability.


title:
GFMC calculations of electromagnetic moments and M1 transitions in
  $A\leq 9$ nuclei

abstract:
  We present recent Green's function Monte Carlo calculations of magnetic
moments and M1 transitions in $A \leq 9$ nuclei, which include corrections
arising from two-body meson-exchange electromagnetic currents. Two-body effects
provide significant corrections to the calculated observables, bringing them in
excellent agreement with the experimental data. In particular, we find that
two-body corrections are especially large in the A=9, $T=3/2$ systems, in which
they account for up to $\sim 20%$ ($\sim 40 %$) of the total predicted value
for the $^9$Li ($^9$C) magnetic moment.


title: Massive Gravity with N=1 local Supersymmetry

abstract:
  A consistent theory of massive gravity, where the graviton acquires mass by
spontaneously breaking diffeomorphism invariance, is now well established. We
supersymmetrize this construction using N =1 fields. Coupling to N = 1
supergravity is done by applying the rules of tensor calculus to construct an
action invariant under local N = 1 supersymmetry. The supersymmetric action is
shown, at the quadratic level, to be free of ghosts and have as its spectrum a
massive graviton, two gravitinos with different masses, and a massive vector.


title:
A two weight theorem for fractional singular integrals with an energy
  side condition and quasicube testing

abstract:
  We prove a two weight theorem for fractional singular integrals in higher
dimensions assuming energy side conditions on the weights. The testing
conditions are taken over quasicubes, namely globally biLipschitz images of
cubes.


title:
Photoelectron spin-flipping and texture manipulation in a topological
  insulator

abstract:
  Recently discovered materials called three-dimensional topological insulators
constitute examples of symmetry protected topological states in the absence of
applied magnetic fields and cryogenic temperatures. A hallmark characteristic
of these non-magnetic bulk insulators is the protected metallic electronic
states confined to the material's surfaces. Electrons in these surface states
are spin polarized with their spins governed by their direction of travel
(linear momentum), resulting in a helical spin texture in momentum space. Spin-
and angle-resolved photoemission spectroscopy (spin-ARPES) has been the only
tool capable of directly observing this central feature with simultaneous
energy, momentum, and spin sensitivity. By using an innovative photoelectron
spectrometer with a high-flux laser-based light source, we discovered another
surprising property of these surface electrons which behave like Dirac
fermions. We found that the spin polarization of the resulting photoelectrons
can be fully manipulated in all three dimensions through selection of the light
polarization. These surprising effects are due to the spin-dependent
interaction of the helical Dirac fermions with light, which originates from the
strong spin-orbit coupling in the material. Our results illustrate unusual
scenarios in which the spin polarization of photoelectrons is completely
different from the spin state of electrons in the originating initial states.
The results also provide the basis for a novel source of highly spin-polarized
electrons with tunable polarization in three dimensions.


title: Elementary results on K processes with weights

abstract:
  We introduce the title process via a particular construction, and relate it
to processes previously studied, in particular a process introduced by G. E. H.
Reuter in 1969. We derive elementary properties and quantities of this
processes: Markov property, transition rates, stationary distribution, and the
infinitesimal generator for a case not treated by Reuter.


title: Bigravity in Kuchar's Hamiltonian formalism. 2. The special case

abstract:
  It is proved, that, in order to avoid the ghost mode in bigravity theory, it
is sufficient to impose four conditions on the potential of interaction of the
two metrics. First, the potential should allow its expression as a function of
components of the two metrics' 3+1 decomposition. Second, the potential must
satisfy the first order linear differential equations which are necessary for
the presence of four first class constraints in bigravity. Third, the potential
should be a solution of the Monge-Ampere equation, where the lapse and shift
are considered as variables. Fourth, the potential must have a nondegenerate
Hessian in the shift variables. The proof is based on the explicit derivation
of the Hamiltonian constraints, the construction of Dirac brackets on the base
of a part of these constraints, and calculation of other constraints' algebra
in these Dirac brackets. As a byproduct, we prove that these conditions are
also sufficient in the massive gravity case.


title: Magnetostrictive thin films for microwave spintronics

abstract:
  Multiferroic composite materials, consisting of coupled ferromagnetic and
piezoelectric phases, are of great importance in the drive towards creating
faster, smaller and more energy efficient devices for information and
communications technologies. Such devices require thin ferromagnetic films with
large magnetostriction and narrow microwave resonance linewidths. Both
properties are often degraded, compared to bulk materials, due to structural
imperfections and interface effects in the thin films. We report the
development of single crystal thin films of Galfenol (Fe81Ga19) with
magnetostriction as large as the best reported values for bulk material. This
allows the magnetic anisotropy and microwave resonant frequency to be tuned by
voltage-induced strain, with a larger magnetoelectric response and a narrower
linewidth than any previously reported Galfenol thin films. The combination of
these properties make the single crystal thin films excellent candidates for
developing tunable devices for magnetic information storage, processing and
microwave communications.


title: The chromo-Weibel instability in an expanding background

abstract:
  In this proceedings contribution we review recent calculations of the
dynamics of the chromo-Weibel instability in the quark gluon plasma. This
instability is present in gauge theories with a one-particle distribution
function which is momentum-space anisotropic in the local rest frame. The
conditions necessary for triggering this instability can be present already in
the color-glass-condensate initial state or dynamically generated by the rapid
longitudinal expansion of the matter created in a heavy-ion collision. Using
the hard-loop framework we study the case that the one-particle distribution
function possesses an arbitrary initial momentum anisotropy that increases in
time due to longitudinal free streaming. The resulting three-dimensional
dynamical equations for the chromofield evolution are solved numerically. We
find that there is regeneration of the longitudinal pressure due to unstable
plasma modes; nevertheless, the system seems to maintain a high-degree of
momentum-space anisotropy. Despite this anisotropy, we find that there is rapid
longitudinal thermalization of the plasma due to the non-linear mode couplings
inherent in the unstable evolution.


title:
Frustration-induced nanometre-scale inhomogeneity in a triangular
  antiferromagnet

abstract:
  Phase inhomogeneity of otherwise chemically homogenous electronic systems is
an essential ingredient leading to fascinating functional properties, such as
high-$T_c$ superconductivity in cuprates, colossal magnetoresistance in
manganites, and giant electrostriction in relaxors. In these materials distinct
phases compete and can coexist due to intertwined ordered parameters. Charge
degrees of freedom play a fundamental role, although phase-separated ground
states have been envisioned theoretically also for pure spin systems with
geometrical frustration that serves as a source of phase competition. Here we
report a paradigmatic magnetostructurally inhomogenous ground state of the
geometrically frustrated $\alpha$-NaMnO$_2$ that stems from the system's
aspiration to remove magnetic degeneracy and is possible only due to the
existence of near-degenerate crystal structures. Synchrotron X-ray diffraction,
nuclear magnetic resonance and muon spin relaxation show that the spin
configuration of a monoclinic phase is disrupted by magnetically short-range
ordered nanoscale triclinic regions, thus revealing a novel complex state of
matter.


title: Magnetic Avalanches in Molecular Magnets

abstract:
  The reversal of the magnetization of crystals of molecular magnets that have
a large spin and high anisotropy barrier generally proceeds below the blocking
temperature by quantum tunneling. This is manifested as a series of controlled
steps in the hysteresis loops at resonant values of the magnetic field where
energy levels on opposite sides of the barrier cross. An abrupt reversal of the
magnetic moment of the entire crystal can occur instead by a process commonly
referred to as a magnetic avalanche, where the molecular spins reverse along a
deflagration front that travels through the sample at subsonic speed. In this
chapter, we review experimental results obtained to date for magnetic
deflagration in molecular nanomagnets.


title: Optimizing Password Composition Policies

abstract:
  A password composition policy restricts the space of allowable passwords to
eliminate weak passwords that are vulnerable to statistical guessing attacks.
Usability studies have demonstrated that existing password composition policies
can sometimes result in weaker password distributions; hence a more principled
approach is needed. We introduce the first theoretical model for optimizing
password composition policies. We study the computational and sample complexity
of this problem under different assumptions on the structure of policies and on
users' preferences over passwords. Our main positive result is an algorithm
that -- with high probability --- constructs almost optimal policies (which are
specified as a union of subsets of allowed passwords), and requires only a
small number of samples of users' preferred passwords. We complement our
theoretical results with simulations using a real-world dataset of 32 million
passwords.


title: Intrinsic Supermoothness

abstract:
  The phenomenon, known as "supersmoothness" was first observed for bivariate
splines and attributed to the polynomial nature of splines. Using only standard
tools from multivatiate calculus, we show that if we continuously glue two
smooth functions along a curve with a "corner", the resulting continuous
function must be differentiable at the corner, as if to compensate for the
singularity of the curve. Moreover, locally, this property, we call
supersmoothness, characterizes non-smooth curves. We also generalize this
phenomenon to higher order derivatives. In particular, this shows that
supersmoothness has little to do with properties of polynomials.


title:
Ground-state OH molecule in combined electric and magnetic fields:
  Analytic solution of the effective Hamiltonian

abstract:
  The OH molecule is currently of great interest from the perspective of
ultracold chemistry, quantum fluids, precision measurement and quantum
computation. Crucial to these applications are the slowing, guiding,
confinement and state control of OH, using electric and magnetic fields. In
this article, we show that the corresponding eight-dimensional effective ground
state Stark-Zeeman Hamiltonian is exactly solvable and explicitly identify the
underlying chiral symmetry. Our analytical solution opens the way to insightful
characterization of the magnetoelectrostatic manipulation of ground state OH.
Based on our results, we also discuss a possible application to the quantum
simulation of an imbalanced Ising magnet.


title:
Inferring ancestral states without assuming neutrality or gradualism
  using a stable model of continuous character evolution

abstract:
  The value of a continuous character evolving on a phylogenetic tree is
commonly modelled as the location of a particle moving under one-dimensional
Brownian motion with constant rate. The Brownian motion model is best suited to
characters evolving under neutral drift or tracking an optimum that drifts
neutrally. We present a generalization of the Brownian motion model which
relaxes assumptions of neutrality and gradualism by considering increments to
evolving characters to be drawn from a heavy-tailed stable distribution (of
which the normal distribution is a specialized form). We describe Markov chain
Monte Carlo methods for fitting the model to biological data paying special
attention to ancestral state reconstruction, and study the performance of the
model in comparison with a selection of existing comparative methods, using
both simulated data and a database of body mass in 1,679 mammalian species. We
discuss hypothesis testing and model selection. The new model is well suited to
a stochastic process with a volatile rate of change in which biological
characters undergo a mixture of neutral drift and occasional evolutionary
events of large magnitude.


title: Geometric visualization of self-propulsion in a complex medium

abstract:
  Combining geometric mechanics theory, laboratory robotic experiment and
numerical simulation, we study the locomotion in granular media (GM) of the
simplest non-inertial swimmer, the Purcell three-link swimmer. Using granular
resistive force laws as inputs, the theory relates translation and rotation of
the body to shape changes (movements of the links). This allows analysis,
visualization, and prediction of effective movements that are verified by
experiment. The geometric approach also facilitates comparison between swimming
in GM and in viscous fluids.


title: Diagonals of self-adjoint operators with finite spectrum

abstract:
  Given a finite set $X\subseteq\R$ we characterize the diagonals of
self-adjoint operators with spectrum $X$. Our result extends the Schur-Horn
theorem from a finite dimensional setting to an infinite dimensional Hilbert
space analogous to Kadison's theorem for orthogonal projections and the second
author's result for operators with three point spectrum.


title: Van der Waals and Casimir interactions between two graphene sheets

abstract:
  The thermal free energy and pressure of dispersion interaction between two
graphene sheets described by the Dirac model are calculated using the Lifshitz
formula with reflection coefficients expressed via the polarization tensor. The
obtained results for a pristine graphene are found to be in agreement with
computations using Coulomb coupling between density fluctuations. For a
graphene with nonzero mass gap parameter a qualitatively different behavior for
the free energy and pressure is obtained. The Lifshitz formula with reflection
coefficients expressed via the polarization tensor is used as a test for
different computational approaches proposed in the literature for modeling the
response function and conductivity of graphene at both zero and nonzero
temperature.


title: Anti-Invariant Riemannian Submersions from Cosymplectic Manifolds

abstract:
  We introduce anti-invariant Riemannian submersions from cosymplectic
manifolds onto Riemannian manifolds. We survey main results of anti-invariant
Riemannian submersions defined on cosymplectic manifolds. We investigate
necessary and sufficient condition for an anti-invariant Riemannian submersion
to be totally geodesic and harmonic. We give examples of anti-invariant
submersions such that characteristic vector field {\xi} is vertical or
horizontal. Moreover we give decomposition theorems by using the existence of
anti-invariant Riemannian submersions.


title: Capturing Information Flows inside Android and Qemu Environments

abstract:
  The smartphone market has grown so wide that it assumed a strategic
relevance. Today the most common smartphone OSs are Google's Android and
Apple's iOS. The former is particularly interesting due to its open source
nature, that allows everyone to deeply inspect every aspect of the OS. Android
source code is also bundled with an hardware emulator, based on the open source
software Qemu, that allows the user to run the Android OS without the need of a
physical device. We first present a procedure to extract information flows from
a generic system. We then focus on Android and Qemu architectures and their
logging infrastructures. Finally, we detail what happens inside an Android
device in a particular scenario: the system boot.


title:
The Stellar Masses of ~40,000 UV Selected Galaxies from the WiggleZ
  Survey at 0.3<z<1.0: Analogues of Lyman Break Galaxies?

abstract:
  We characterise the stellar masses and star formation rates in a sample of
almost 40000 spectroscopically confirmed UV luminous galaxies at 0.3<z<1.0
selected from within the WiggleZ Dark Energy Survey. In particular, we match
this UV bright population to wide-field infrared surveys such as the near
infrared UKIDSS LAS and the mid infrared WISE All-Sky Survey. We find that ~30%
of the UV luminous WiggleZ galaxies are detected at >5sigma in the UKIDSS-LAS
at all redshifts. An even more luminous subset of 15% are also detected in the
WISE 3.4 and 4.6um bands. We compute stellar masses for this very large sample
of extremely blue galaxies and quantify the sensitivity of the stellar mass
estimates to various assumptions made during the SED fitting. The median
stellar masses are log10(M*/M0)=9.6\pm0.7, 10.2\pm0.5 and 10.4\pm0.4 for the
IR-undetected, UKIDSS detected and UKIDSS+WISE detected galaxies respectively.
We demonstrate that the inclusion of NIR photometry can lead to tighter
constraints on the stellar masses. The mass estimates are found to be most
sensitive to the inclusion of secondary bursts of star formation as well as
changes in the stellar population synthesis models, both of which can lead to
median discrepancies of the order of 0.3dex in the stellar masses. We find that
the best-fit M/LK is significantly lower (by ~0.4 dex) than that predicted by
simple optical colour based estimators, in particular for the bluer galaxies
with younger best-fit ages. The WiggleZ galaxies have star formation rates of
3-10 M0/yr and mostly lie at the upper end of the main sequence of star-forming
galaxies at these redshifts. Their rest-frame UV luminosities and stellar
masses are comparable to both local compact UV-luminous galaxies as well as
Lyman break galaxies at z~2-3.(abridged)


title:
The Velocity Anisotropy of Distant Milky Way Halo Stars from Hubble
  Space Telescope Proper Motions

abstract:
  Based on long baseline (5-7 years) multi-epoch HST/ACS photometry, used
previously to measure the proper motion of M31, we present the proper motions
(PMs) of 13 main-sequence Milky Way halo stars. The sample lies at an average
distance of r ~24 kpc from the Galactic center, with a root-mean-square spread
of 6 kpc. At this distance, the median PM accuracy is 5 km/s. We devise a
maximum likelihood routine to determine the tangential velocity ellipsoid of
the stellar halo. The velocity second moments in the directions of the Galactic
(l,b) system are < vl^2 >^{1/2} = 123 (+29, -23) km/s, and < vb^2 >^{1/2} = 83
(+24, -16) km/s. We combine these results with the known line-of-sight second
moment, < vlos^2 >^{1/2} = 105 \pm 5$ km/s, at this < r > to study the velocity
anisotropy of the halo. We find approximate isotropy between the radial and
tangential velocity distributions, with anisotropy parameter beta = 0.0 (+0.2,
-0.4). Our results suggest that the stellar halo velocity anisotropy out to r ~
30 kpc is less radially biased than solar neighborhood measurements. This is
opposite to what is expected from violent relaxation, and may indicate the
presence of a shell-type structure at r ~ 24 kpc. With additional multi-epoch
HST data, the method presented here has the ability to measure the transverse
kinematics of the halo for more stars, and to larger distances. This can yield
new improved constraints on the stellar halo formation mechanism, and the mass
of the Milky Way.


title: Is the Galactic Cosmic Ray Spectrum Constant in Time?

abstract:
  The hypothesis is considered that the present Galactic cosmic ray spectrum is
at present softer than its time average due to source intermittency.
Measurements of muogenic nuclides underground could provide an independent
measurement of the time averaged spectrum. Source intermittency could also
account for the surprising low anisotropy reported by the IceCube
collaboration. Predictions for Galactic emission of ultrahigh-energy quanta,
such as UHE gamma rays and neutrinos, might be higher or lower than previously
estimated.


title: Superconductivity of disordered Dirac fermions

abstract:
  We study the effect of disorder on massless, spinful Dirac fermions in two
spatial dimensions with attractive interactions, and show that the combination
of disorder and attractive interactions is deadly to the Dirac semimetal phase.
First, we derive the zero temperature phase diagram of a clean Dirac fermion
system with tunable doping level ({\mu}) and attraction strength (g). We show
that it contains two phases: a superconductor and a Dirac semimetal. Then, we
show that arbitrarily weak disorder destroys the Dirac semimetal, turning it
into a superconductor. We discuss the strength of the superconductivity for
both long range and short range disorder. For long range disorder, the
superconductivity is exponentially weak in the disorder strength. For short
range disorder, a uniform mean field analysis predicts that superconductivity
should be doubly exponentially weak in the disorder strength. However, a more
careful treatment of mesoscopic fluctuations suggests that locally
superconducting puddles should form at a much higher temperature, and should
establish global phase coherence at a temperature that is only exponentially
small in weak disorder. We also discuss the effect of disorder on the quantum
critical point of the clean system, building in the effect of disorder through
a replica field theory. We show that disorder is a relevant perturbation to the
supersymmetric quantum critical point. We expect that in the presence of
attractive interactions, the flow away from the critical point ends up in the
superconducting phase, although firm conclusions cannot be drawn since the
renormalization group analysis flows to strong coupling. We argue that although
we expect the quantum critical point to get buried under a superconducting
phase, signatures of the critical point may be visible in the finite
temperature quantum critical regime.

categories: cond-mat.str-el cond-mat.mes-hall cond-mat.stat-mech cond-mat.supr-con


title: X-Ray Groups of Galaxies in the Aegis Deep and Wide Fields

abstract:
  We present the results of a search for extended X-ray sources and their
corresponding galaxy groups from 800-ks Chandra coverage of the All-wavelength
Extended Groth Strip International Survey (AEGIS). This yields one of the
largest X-ray selected galaxy group catalogs from a blind survey to date. The
red-sequence technique and spectroscopic redshifts allow us to identify 100$%$
of reliable sources, leading to a catalog of 52 galaxy groups. The groups span
the redshift range $z\sim0.066-1.544$ and virial mass range
$M_{200}\sim1.34\times 10^{13}-1.33\times 10^{14}M_\odot$. For the 49 extended
sources which lie within DEEP2 and DEEP3 Galaxy Redshift Survey coverage, we
identify spectroscopic counterparts and determine velocity dispersions. We
select member galaxies by applying different cuts along the line of sight or in
projected spatial coordinates. A constant cut along the line of sight can cause
a large scatter in scaling relations in low-mass or high-mass systems depending
on the size of cut. A velocity dispersion based virial radius can more
overestimate velocity dispersion in comparison to X-ray based virial radius for
low mass systems. There is no significant difference between these two radial
cuts for more massive systems. Independent of radial cut, overestimation of
velocity dispersion can be created in case of existence of significant
substructure and also compactness in X-ray emission which mostly occur in low
mass systems. We also present a comparison between X-ray galaxy groups and
optical galaxy groups detected using the Voronoi-Delaunay method (VDM) for
DEEP2 data in this field.


title:
Newly-quenched galaxies as the cause for the apparent evolution in
  average size of the population

abstract:
  Abridged. We use COSMOS to study in a self-consistent way the change in the
number densities of quenched early-type galaxies (Q-ETGs) of a given size over
the interval 0.2 < z < 1.0 to study the claimed size evolution of these
galaxies. At 10^10.5<Mgalaxy<10^11 Msun, we see no change in the number density
of compact Q-ETGs, while at >10^11 Msun we find a decrease by 30%. In both mass
bins, the increase of the median sizes of Q-ETGs with time is primarily caused
by the addition to the size function of larger and more diffuse Q-ETGs. At all
masses, compact Q-ETGs become systematically redder towards later epochs, with
a (U-V) difference consistent with passive evolution of their stellar
populations, indicating that they are a population that does not appreciably
evolve in size. At all epochs, the larger Q-ETGs (at least in the lower mass
bin) have average rest-frame colors systematically bluer than those of the more
compact Q-ETGs, suggesting that the former are younger than the latter. The
idea that new, large, Q-ETGs are responsible for the observed growth in the
median size of the population at a given mass is supported by the sizes and
number of the star-forming galaxies that are expected to be progenitors of the
new Q-ETGs over the same period. In the low mass bin, the new Q-ETG have 30%
smaller sizes than their star-forming progenitors. This is likely due to the
fading of their disks after they cease star-formation. Comparison with higher z
shows that the median size of newly-quenched galaxies roughly scales, at
constant mass, as (1+z)^-1. The dominant cause of the size evolution seen in
the Q-ETG population is thus that the average sizes of individual Q-ETGs scale
with the average density of the Universe at the time when they were quenched,
with subsequent size changes in individual objects through eg merging of
secondary importance, especially at masses <10^11 Msun.


title: The Black Hole and Central Stellar Population of MCG--6-30-15

abstract:
  We present the first near-infrared integral field spectroscopy observations
of the galaxy MCG--6-30-15. The H-band data studied in this paper cover the
central 500 pc of the galaxy at the best resolution (0".1) so far. The spectra
of the innermost regions are dominated by broad brackett series emission lines
and non-stellar continuum, under which we are able to trace the distribution
and kinematics of the stars and also the [Fe II] line emission. We find that
there is a counter-rotating stellar core extending out to 125 pc, which appears
to be associated with the [Fe II] emission. Based on the mass-to-light ratio,
and the presence of this emission line, we estimate the age of the central
stellar population to be of order of 65 Myr. We show that the gas needed to
fuel the black hole is, at most, only 1 per cent of that needed to form these
stars. We derive independent constraints on the black hole mass using the
dynamical information and determine an upper limit for the black hole mass, Mbh
< 6e7 Msun, that is consistent with other estimates.


title: Transport signatures of spatially modulated electronic nematic phases

abstract:
  Electronic nematic phases are broadly characterized by spontaneously broken
rotational symmetry. Although they have been widely recognized in the context
of high temperature cuprates, bilayer ruthenates, and iron-based
superconductors, the focus so far has been exclusively on the uniform nematic
phase. Recently, however, it was proposed that on a square lattice a nematic
instability in the d-wave charge channel could lead to a spatially modulated
nematic state, where the modulation vector q is determined by the relative
location of the Fermi level to the van Hove singularity. Interestingly, this
finite-q nematic phase has also been identified as an additional leading
instability that is as strong as the superconducting instability near the onset
of spin density wave order. Here we study the electrical conductivity tensor in
the modulated nematic phase for a general modulation vector. Our results can be
used to identify modulated nematic phases in correlated materials.


title:
Colocalization of coregulated genes: a steered molecular dynamics study
  of human chromosome 19

abstract:
  The connection between chromatin nuclear organization and gene activity is
vividly illustrated by the observation that transcriptional coregulation of
certain genes appears to be directly influenced by their spatial proximity.
This fact poses the more general question of whether it is at all feasible that
the numerous genes that are coregulated on a given chromosome, especially those
at large genomic distances, might become proximate inside the nucleus. This
problem is studied here using steered molecular dynamics simulations in order
to enforce the colocalization of thousands of knowledge-based gene sequences on
a model for the gene-rich human chromosome 19. Remarkably, it is found that
most (~80%) gene pairs can be brought simultaneously into contact. This is made
possible by the low degree of intra-chromosome entanglement and the large
number of cliques in the gene coregulatory network, that is the many groups of
genes that are all mutually coregulated. The constrained conformations for the
model chromosome 19 are further shown to be organised in spatial macrodomains
that are similar to those inferred from recent HiC measurements. The findings
indicate that gene coregulation and colocalization are largely compatible and
that this relationship can be exploited to draft the overall spatial
organization of the chromosome in vivo. The more general validity and
implications of these findings could be investigated by applying to other
eukaryotic chromosomes the general and transferable computational strategy
introduced here.

categories: q-bio.GN cond-mat.soft cond-mat.stat-mech physics.bio-ph


title:
Chemical surface inhomogeneities in late B-type stars with Hg and Mn
  peculiarity I Spot evolution in HD 11753 on short and long time scales

abstract:
  Aims: Time series of high-resolution spectra of the late B-type star HD 11753
exhibiting HgMn chemical peculiarity are used to study the surface distribution
of different chemical elements and their temporal evolution. Methods:
High-resolution and high signal-to-noise ratio spectra were obtained using the
CORALIE spectrograph at La Silla in 2000, 2009, and 2010. Surface maps of YII,
SrII, TiII, and CrII were calculated using the Doppler imaging technique. The
results were also compared to equivalent width measurements. The evolution of
chemical spots both on short and long time scales were investigated. Results:
We determine the binary orbit of HD 11753 and fine-tune the rotation period of
the primary. The earlier discovered fast evolution of the chemical spots is
confirmed by an analysis using both the chemical spot maps and equivalent width
measurements. In addition, a long-term decrease in the overall YII and SrII
abundances is discovered. A detailed analysis of the chemical spot
configurations reveals some possible evidence that a very weak differential
rotation is operating in HD 11753.


title:
An efficient attack of a McEliece cryptosystem variant based on
  convolutional codes

abstract:
  L\"ondahl and Johansson proposed last year a variant of the McEliece
cryptosystem which replaces Goppa codes by convolutional codes. This
modification is supposed to make structural attacks more difficult since the
public generator matrix of this scheme contains large parts which are generated
completely at random. They proposed two schemes of this kind, one of them
consists in taking a Goppa code and extending it by adding a generator matrix
of a time varying convolutional code. We show here that this scheme can be
successfully attacked by looking for low-weight codewords in the public code of
this scheme and using it to unravel the convolutional part. It remains to break
the Goppa part of this scheme which can be done in less than a day of
computation in the case at hand.


title: Three-coloring triangle-free planar graphs in linear time

abstract:
  Grotzsch's theorem states that every triangle-free planar graph is
3-colorable. Several relatively simple proofs of this fact were provided by
Thomassen and other authors. It is easy to convert these proofs into
quadratic-time algorithms to find a 3-coloring, but it is not clear how to find
such a coloring in linear time (Kowalik used a nontrivial data structure to
construct an O(n log n) algorithm).
  We design a linear-time algorithm to find a 3-coloring of a given
triangle-free planar graph. The algorithm avoids using any complex data
structures, which makes it easy to implement. As a by-product we give a yet
simpler proof of Grotzsch's theorem.


title: Naturally Rehearsing Passwords

abstract:
  We introduce quantitative usability and security models to guide the design
of password management schemes --- systematic strategies to help users create
and remember multiple passwords. In the same way that security proofs in
cryptography are based on complexity-theoretic assumptions (e.g., hardness of
factoring and discrete logarithm), we quantify usability by introducing
usability assumptions. In particular, password management relies on assumptions
about human memory, e.g., that a user who follows a particular rehearsal
schedule will successfully maintain the corresponding memory. These assumptions
are informed by research in cognitive science and validated through empirical
studies. Given rehearsal requirements and a user's visitation schedule for each
account, we use the total number of extra rehearsals that the user would have
to do to remember all of his passwords as a measure of the usability of the
password scheme. Our usability model leads us to a key observation: password
reuse benefits users not only by reducing the number of passwords that the user
has to memorize, but more importantly by increasing the natural rehearsal rate
for each password. We also present a security model which accounts for the
complexity of password management with multiple accounts and associated
threats, including online, offline, and plaintext password leak attacks.
Observing that current password management schemes are either insecure or
unusable, we present Shared Cues--- a new scheme in which the underlying secret
is strategically shared across accounts to ensure that most rehearsal
requirements are satisfied naturally while simultaneously providing strong
security. The construction uses the Chinese Remainder Theorem to achieve these
competing goals.


title:
Strain and band-mixing effects on the excitonic Aharonov-Bohm effect in
  In(Ga)As/GaAs ringlike quantum dots

abstract:
  Neutral excitons in strained axially symmetric In(Ga)As/GaAs quantum dots
with ringlike shape are investigated. Similar to experimental self-assembled
quantum rings, the analyzed quantum dots have volcano-like shapes. The
continuum mechanical model is employed to determine the strain distribution,
and the single-band envelope function approach is adopted to compute the
electron states. The hole states are determined by the axially symmetric
multiband Luttinger-Kohn Hamiltonian, and the exciton states are obtained from
an exact diagonalization. We found that the presence of the inner layer
covering the ring opening enhances the excitonic Aharonov-Bohm (AB)
oscillations. The reason is that the hole becomes mainly localized in the inner
part of the quantum dot due to strain, whereas the electron resides mainly
inside the ring-shaped rim. Interestingly, larger AB oscillations are found in
the analyzed quantum dot than in a fully opened quantum ring of the same width.
Comparison with the unstrained ring-like quantum dot shows that the amplitude
of the excitonic Aharonov-Bohm oscillations are almost doubled in the presence
of strain. The computed oscillations of the exciton energy levels are
comparable in magnitude to the oscillations measured in recent experiments.


title:
The Origin of Dust in Early-Type Galaxies and Implications for Accretion
  onto Supermassive Black Holes

abstract:
  We have conducted an archival Spitzer study of 38 early-type galaxies (ETGs)
in order to determine the origin of the dust in approximately half of this
population. Our sample galaxies generally have good wavelength coverage from
3.6um to 160um, as well as visible-wavelength HST images. We use the Spitzer
data to estimate dust masses, or establish upper limits, and find that all of
the ETGs with dust lanes in the HST data are detected in all of the Spitzer
bands and have dust masses of ~10^{5-6.5} Msun, while galaxies without dust
lanes are not detected at 70um and 160um and typically have <10^5 Msun of dust.
The apparently dust-free galaxies do have 24um emission that scales with the
shorter wavelength flux, yet substantially exceeds the expectations of
photospheric emission by approximately a factor of three. We conclude this
emission is dominated by hot, circumstellar dust around evolved stars that does
not survive to form a substantial interstellar component. The order of
magnitude variations in dust masses between galaxies with similar stellar
populations rules out a subtantial contribution from continual, internal
production in spite of the clear evidence for circumstellar dust. We
demonstrate that the interstellar dust is not due to purely external accretion,
unless the product of the merger rate of dusty satellites and the dust lifetime
is at least an order of magnitude higher than expected. We propose that dust in
ETGs is seeded by external accretion, yet the accreted dust is maintained by
continued growth in externally-accreted cold gas beyond the nominal lifetime of
individual grains. The several Gyr depletion time of the cold gas is long
enough to reconcile the fraction of dusty ETGs with the merger rate of gas-rich
satellites. As the majority of dusty ETGs are also low-luminosity AGN and
likely fueled by this cold gas, their lifetime should similarly be several Gyr.


title: High-Dimensional Probability Estimation with Deep Density Models

abstract:
  One of the fundamental problems in machine learning is the estimation of a
probability distribution from data. Many techniques have been proposed to study
the structure of data, most often building around the assumption that
observations lie on a lower-dimensional manifold of high probability. It has
been more difficult, however, to exploit this insight to build explicit,
tractable density models for high-dimensional data. In this paper, we introduce
the deep density model (DDM), a new approach to density estimation. We exploit
insights from deep learning to construct a bijective map to a representation
space, under which the transformation of the distribution of the data is
approximately factorized and has identical and known marginal densities. The
simplicity of the latent distribution under the model allows us to feasibly
explore it, and the invertibility of the map to characterize contraction of
measure across it. This enables us to compute normalized densities for
out-of-sample data. This combination of tractability and flexibility allows us
to tackle a variety of probabilistic tasks on high-dimensional datasets,
including: rapid computation of normalized densities at test-time without
evaluating a partition function; generation of samples without MCMC; and
characterization of the joint entropy of the data.


title: Proton scattering on an electron gas

abstract:
  It is shown in the case of proton scattering on an electron gas target that
the Closed Time Path formalism can handle final state interactions of the
target in equilibrium in a simple and natural manner. The leading order cross
section is proportional to the photon density of states. The scattering needs a
partial resummation of the perturbation series when the electron gas forms long
living quasi-particles with high density of state during the collision. A
strong cancellation between real and virtual electron-hole pairs is found in
this case.


title:
On the k-Independence Required by Linear Probing and Minwise
  Independence

abstract:
  We show that linear probing requires 5-independent hash functions for
expected constant-time performance, matching an upper bound of [Pagh et al.
STOC'07]. More precisely, we construct a 4-independent hash functions yielding
expected logarithmic search time.
  For (1+{\epsilon})-approximate minwise independence, we show that \Omega(log
1/{\epsilon})-independent hash functions are required, matching an upper bound
of [Indyk, SODA'99].
  We also show that the very fast 2-independent multiply-shift scheme of
Dietzfelbinger [STACS'96] fails badly in both applications.


title:
Comment on "Steady-state fluctuations of a genetic feedback loop: an
  exact solution" [J. Chem. Phys. {\bf 137}, 035104 (2012).]

abstract:
  The comment is intended to answer the criticism presented on `Steady-state
fluctuations of a genetic feedback loop: an exact solution' [J. Chem. Phys.
{\bf 137}, 035104 (2012).] and provides the missing component for the complete
analytic solutions to the author's model.


title: Machine-assisted discovery of relationships in astronomy

abstract:
  High-volume feature-rich data sets are becoming the bread-and-butter of 21st
century astronomy but present significant challenges to scientific discovery.
In particular, identifying scientifically significant relationships between
sets of parameters is non-trivial. Similar problems in biological and
geosciences have led to the development of systems which can explore large
parameter spaces and identify potentially interesting sets of associations. In
this paper, we describe the application of automated discovery systems of
relationships to astronomical data sets, focussing on an evolutionary
programming technique and an information-theory technique. We demonstrate their
use with classical astronomical relationships - the Hertzsprung-Russell diagram
and the fundamental plane of elliptical galaxies. We also show how they work
with the issue of binary classification which is relevant to the next
generation of large synoptic sky surveys, such as LSST. We find that comparable
results to more familiar techniques, such as decision trees, are achievable.
Finally, we consider the reality of the relationships discovered and how this
can be used for feature selection and extraction.


title: Quantum-inspired Huffman Coding

abstract:
  Huffman Compression, also known as Huffman Coding, is one of many compression
techniques in use today. The two important features of Huffman coding are
instantaneousness that is the codes can be interpreted as soon as they are
received and variable length that is a most frequent symbol has length smaller
than a less frequent symbol. The traditional Huffman coding has two procedures:
constructing a tree in O(n^2) and then traversing it in O(n). Quantum computing
is a promising approach of computation that is based on equations from Quantum
Mechanics. Instantaneousness and variable length features are difficult to
generalize to the quantum case. The quantum coding field is pioneered by
Schumacher works on block coding scheme. To encode N signals sequentially, it
requires O(N3) computational steps. The encoding and decoding processes are far
from instantaneous. Moreover, the lengths of all the codewords are the same. A
Huffman-coding-inspired scheme for the storage of quantum information takes
O(N(log N)a) computational steps for a sequential implementation on
non-parallel machines.


title:
Rational approximations of spectral densities based on the Alpha
  divergence

abstract:
  We approximate a given rational spectral density by one that is consistent
with prescribed second-order statistics. Such an approximation is obtained by
minimizing a suitable distance from the given spectrum and under the
constraints corresponding to imposing the given second-order statistics. Here,
we consider the Alpha divergence family as a distance measure. We show that the
corresponding approximation problem leads to a family of rational solutions.
Secondly, such a family contains the solution which generalizes the
Kullback-Leibler solution proposed by Georgiou and Lindquist in 2003. Finally,
numerical simulations suggest that this family contains solutions close to the
non-rational solution given by the principle of minimum discrimination
information.


title: A Maximum Problem of S.-T. Yau for Variational p-Capacity

abstract:
  Through using the semidiameter (in connection to: the mean radius and surface
radius) of a convex closed hypersurface in $\mathbb R^{n\ge 2}$ as an sharp
upper bound of the variational $(1,n)\ni p$-capacity radius, this paper settles
a restriction/variant of S.-T. Yau's \cite[Problem 59]{Yau} from the surface
area to the variational $p$-capacity whose limit as $p\to 1$ actually induces
the surface area.


title: Q#, a quantum computation package for the .NET platform

abstract:
  Quantum computing is a promising approach of computation that is based on
equations from Quantum Mechanics. A simulator for quantum algorithms must be
capable of performing heavy mathematical matrix transforms. The design of the
simulator itself takes one of three forms: Quantum Turing Machine, Network
Model or circuit model of connected gates or, Quantum Programming Language,
yet, some simulators are hybrid. We studied previous simulators and then we
adopt features from three simulators of different implementation languages,
different paradigms, and for different platforms. They are Quantum Computing
Language (QCL), QUASI, and Quantum Optics Toolbox for Matlab 5. Our simulator
for quantum algorithms takes the form of a package or a programming library for
Quantum computing, with a case study showing the ability of using it in the
circuit model. The .NET is a promising platform for computing. VB.NET is an
easy, high productive programming language with the full power and
functionality provided by the .NET framework. It is highly readable, writeable,
and flexible language, compared to another language such as C#.NET in many
aspects. We adopted VB.NET although its shortage in built-in mathematical
complex and matrix operations, compared to Matlab. For implementation, we first
built a mathematical core of matrix operations. Then, we built a quantum core
which contains: basic qubits and register operations, basic 1D, 2D, and 3D
quantum gates, and multi-view visualization of the quantum state, then a window
for demos to show you how to use and get the most of the package.


title: Spectral Clustering with Unbalanced Data

abstract:
  Spectral clustering (SC) and graph-based semi-supervised learning (SSL)
algorithms are sensitive to how graphs are constructed from data. In particular
if the data has proximal and unbalanced clusters these algorithms can lead to
poor performance on well-known graphs such as $k$-NN, full-RBF,
$\epsilon$-graphs. This is because the objectives such as Ratio-Cut (RCut) or
normalized cut (NCut) attempt to tradeoff cut values with cluster sizes, which
are not tailored to unbalanced data. We propose a novel graph partitioning
framework, which parameterizes a family of graphs by adaptively modulating node
degrees in a $k$-NN graph. We then propose a model selection scheme to choose
sizable clusters which are separated by smallest cut values. Our framework is
able to adapt to varying levels of unbalancedness of data and can be naturally
used for small cluster detection. We theoretically justify our ideas through
limit cut analysis. Unsupervised and semi-supervised experiments on synthetic
and real data sets demonstrate the superiority of our method.


title: Topology by dissipation

abstract:
  Topological states of fermionic matter can be induced by means of a suitably
engineered dissipative dynamics. Dissipation then does not occur as a
perturbation, but rather as the main resource for many-body dynamics, providing
a targeted cooling into a topological phase starting from an arbitrary initial
state. We explore the concept of topological order in this setting, developing
and applying a general theoretical framework based on the system density matrix
which replaces the wave function appropriate for the discussion of Hamiltonian
ground-state physics. We identify key analogies and differences to the more
conventional Hamiltonian scenario. Differences mainly arise from the fact that
the properties of the spectrum and of the state of the system are not as
tightly related as in a Hamiltonian context. We provide a symmetry-based
topological classification of bulk steady states and identify the classes that
are achievable by means of quasi-local dissipative processes driving into
superfluid paired states. We also explore the fate of the bulk-edge
correspondence in the dissipative setting, and demonstrate the emergence of
Majorana edge modes. We illustrate our findings in one- and two-dimensional
models that are experimentally realistic in the context of cold atoms.


title:
Dynamic heterogeneity of glass-forming liquids in the density scaling
  regime

abstract:
  Recent analyses of high pressure measurement data suggest that the degree of
the dynamic heterogeneity ({\chi}_4)^max cannot be in general a single variable
function of the structural relaxation time {\tau}. For a wide class of real and
model supercooled liquids, the molecular dynamics of which obeys a density
scaling law at least to a good approximation, we argue that the important
relation between the length and time scales that characterize molecular motions
near the glass transition is controlled by a density factor. If a power law
density scaling is valid for both the structural relaxation times and the
degrees of the dynamic heterogeneity we find that the factor is a density
power, the exponent of which is a measure of the observed decoupling between
{\tau} and ({\chi}_4)^max. Then, the measure can be quantified by a difference
between the power law density scaling exponents, which are usually different
for {\tau} and ({\chi}_4)^max.


title: Heat transport and diffusion in a canonical model of a relativistic gas

abstract:
  Relativistic transport phenomena are important from both theoretical and
practical point of view. Accordingly, hydrodynamics of relativistic gas has
been extensively studied theoretically. Here, we introduce a three-dimensional
canonical model of hard-sphere relativistic gas which allows us to impose
appropriate temperature gradient along a given direction maintaining the system
in a non-equilibrium steady state. We use such a numerical laboratory to study
the appropriateness of the so-called first order (Chapman-Enskog) relativistic
hydrodynamics by calculating various transport coefficients. Our numerical
results are consistent with predictions of such a theory for a wide range of
temperatures. Our results are somewhat surprising since such linear theories
are not consistent with the fundamental assumption of the special theory of
relativity ($v\leq c$). We therefore seek to explain such results by studying
the appropriateness of diffusive transport in the relativistic gas, comparing
our results with that of a classical gas. We find that the relativistic
correction (constraint) in the hydrodynamic limit amounts to small negligible
corrections, thus indicating the validity of the linear approximation in near
equilibrium transport phenomena.


title:
The Resurgence of Instantons: Multi-Cut Stokes Phases and the Painleve
  II Equation

abstract:
  Resurgent transseries have recently been shown to be a very powerful
construction in order to completely describe nonperturbative phenomena in both
matrix models and topological or minimal strings. These solutions encode the
full nonperturbative content of a given gauge or string theory, where
resurgence relates every (generalized) multi-instanton sector to each other via
large-order analysis. The Stokes phase is the adequate gauge theory phase where
an 't Hooft large N expansion exists and where resurgent transseries are most
simply constructed. This paper addresses the nonperturbative study of Stokes
phases associated to multi-cut solutions of generic matrix models, constructing
nonperturbative solutions for their free energies and exploring the asymptotic
large-order behavior around distinct multi-instanton sectors. Explicit formulae
are presented for the Z_2 symmetric two-cut set-up, addressing the cases of the
quartic matrix model in its two-cut Stokes phase; the "triple" Penner potential
which yields four-point correlation functions in the AGT framework; and the
Painleve II equation describing minimal superstrings.

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


title: Hierarchical clustering and the BAO signature

abstract:
  In this contribution we present the preliminary results regarding the
non-linear BAO signal in higher-order statistics of the cosmic density field.
We use ensembles of N-body simulations to show that the non-linear evolution
changes the amplitudes of the BAO signal, but has a negligible effect on the
scale of the BAO feature. The latter observation accompanied by the fact that
the BAO feature amplitude roughly doubles as one moves to higher orders,
suggests that the higher-order correlation amplitudes can be used as probe of
the BAO signal.


title:
Exotic spin orders driven by orbital fluctuations in the Kugel-Khomskii
  model

abstract:
  We study zero temperature phase diagram of the three-dimensional
Kugel-Khomskii model on a cubic lattice using the cluster mean field theory and
different perturbative expansions in the orbital sector. The phase diagram is
rich, goes beyond the single-site mean field theory due to spin-orbital
entanglement. In addition to the antiferromagnetic (AF) and ferromagnetic (FM)
phases, one finds also a plaquette valence-bond phase with singlets ordered
either on horizontal or vertical bonds. More importantly, for increasing Hund's
exchange we identify three phases with exotic magnetic order stabilized by
orbital fluctuations in between the AF and FM order: (i) an AF phase with two
mutually orthogonal antiferromagnets on two sublattices in each $ab$ plane and
AF order along the c axis (ortho-$G$-type phase), (ii) a canted-$A$-type AF
phase with a non-trivial canting angle between nearest neighbor FM layers along
the c axis, and (iii) a striped-AF phase with anisotropic AF order in the $ab$
planes. We elucidate the mechanism responsible for each of the above phases by
deriving effective spin models which involve second and third neighbor
Heisenberg interactions as well as four-site spin interactions going beyond
Heisenberg physics, and explain how the entangled nearest neighbor spin-orbital
superexchange generates spin interactions between more distant spins.


title:
Looking for Stars and Finding the Moon: Effects of Lunar Gamma-ray
  Emission on Fermi LAT Light Curves

abstract:
  We are conducting a search for new gamma-ray binaries by making high
signal-to-noise light curves of all cataloged Fermi LAT sources and searching
for periodic variability using appropriately weighted power spectra. The light
curves are created using a variant of aperture photometry where photons are
weighted by the probability that they came from the source of interest. From
this analysis we find that the light curves of a number of sources near the
ecliptic plane are contaminated by gamma-ray emission from the Moon. This shows
itself as modulation on the Moon's sidereal period in the power spectra. We
demonstrate that this contamination can be removed by excluding times when the
Moon was too close to a source. We advocate that this data screening should
generally be used when analyzing LAT data from a source located close to the
path of the Moon.


title:
Aspects of the history, anatomy, taxonomy and palaeobiology of sauropod
  dinosaurs

abstract:
  Although the sauropod dinosaurs have been recognised for more than a hundred
and sixty years, much remains to be discovered and understood about their
functional anatomy and palaeobiology. Older taxa require revision and new taxa
await description. The characteristic long necks of sauropods are mechanically
perplexing and their evolution is obscure. All these issues are addressed
herein.
  The genus Brachiosaurus is represented by the American type species B.
altithorax and the better known African species B. brancai. However,
examination of the overlapping material shows 26 differences between the
species. B. brancai must be removed from Brachiosaurus and referred to the
genus Giraffatitan, which has been previously proposed for it.
  Xenoposeidon proneneukos is a new neosauropod from the Lower Cretaceous
Hastings Bed Group, known from a single partial dorsal vertebra. The excellent
preservation of the Xenoposeidon holotype reveals six unique characters. The
distinctive morphology suggests that Xenoposeidon may represent a new sauropod
family, extending sauropod disparity as well as bringing to four the number of
sauropod families known from the Wealden.
  A second new Early Cretaceous genus is also described, a titanosauriform from
the Ruby Ranch Member of the Cedar Mountain Formation, in Utah. This taxon is
known from at least two individuals, an adult and a juvenile, which together
provide vertebrae, ribs, a scapula, sternal plates and an ilium. The ilium is
particularly unusual, exhibiting five unique features.
  The longest sauropod necks were five times as long as those of the next
longest terrestrial animals, and four separate lineages evolved necks exceeding
10 m. Elongation was enabled by sheer size, vertebral pneumaticity and the
relative smallness of sauropod heads, despite aspects of cervical osteology
that are difficult to understand on mechanical first principles.


title: Multiplicity-free quantum 6j-symbols for U_q(sl_N)

abstract:
  We conjecture a closed form expression for the simplest class of
multiplicity-free quantum 6j-symbols for U_q(sl_N). The expression is a natural
generalization of the quantum 6j-symbols for U_q(sl_2) obtained by Kirillov and
Reshetikhin. Our conjectured form enables computation of colored HOMFLY
polynomials for various knots and links carrying arbitrary symmetric
representations.


title: Colored HOMFLY polynomials from Chern-Simons theory

abstract:
  We elaborate the Chern-Simons field theoretic method to obtain colored HOMFLY
invariants of knots and links. Using multiplicity-free quantum 6j-symbols for
U_q(sl_N), we present explicit evaluations of the HOMFLY invariants colored by
symmetric representations for a variety of knots, two-component links and
three-component links.


title:
Prediction and Clustering in Signed Networks: A Local to Global
  Perspective

abstract:
  The study of social networks is a burgeoning research area. However, most
existing work deals with networks that simply encode whether relationships
exist or not. In contrast, relationships in signed networks can be positive
("like", "trust") or negative ("dislike", "distrust"). The theory of social
balance shows that signed networks tend to conform to some local patterns that,
in turn, induce certain global characteristics. In this paper, we exploit both
local as well as global aspects of social balance theory for two fundamental
problems in the analysis of signed networks: sign prediction and clustering.
Motivated by local patterns of social balance, we first propose two families of
sign prediction methods: measures of social imbalance (MOIs), and supervised
learning using high order cycles (HOCs). These methods predict signs of edges
based on triangles and \ell-cycles for relatively small values of \ell.
Interestingly, by examining measures of social imbalance, we show that the
classic Katz measure, which is used widely in unsigned link prediction,
actually has a balance theoretic interpretation when applied to signed
networks. Furthermore, motivated by the global structure of balanced networks,
we propose an effective low rank modeling approach for both sign prediction and
clustering. For the low rank modeling approach, we provide theoretical
performance guarantees via convex relaxations, scale it up to large problem
sizes using a matrix factorization based algorithm, and provide extensive
experimental validation including comparisons with local approaches. Our
experimental results indicate that, by adopting a more global viewpoint of
balance structure, we get significant performance and computational gains in
prediction and clustering tasks on signed networks. Our work therefore
highlights the usefulness of the global aspect of balance theory for the
analysis of signed networks.


title:
Formation and switching of defect dipoles in acceptor doped lead
  titanate: A kinetic model based on first-principles calculations

abstract:
  The formation and field-induced switching of defect dipoles in acceptor doped
lead titanate is described by a kinetic model representing an extension of the
well established Arlt-Neumann model [Ferroelectrics {\bf 76}, 303 (1987)].
Energy barriers for defect association and reorientation of oxygen
vacancy-dopant (Cu and Fe) complexes are obtained from first-principles
calculations and serve as input data for the kinetic coefficients in the rate
equation model. The numerical solution of the model describes the time
evolution of the oxygen vacancy distribution at different temperatures and
dopant concentrations in the presence or absence of an alternating external
field. We predict the characteristic time scale for the alignment of all defect
dipoles with the spontanenous polarization of the surrounding matrix. In this
state the defect dipoles act as obstacles for domain wall motion and contribute
to the experimentally observed aging. Under cycling conditions the fully
aligned configuration is perturbed and a dynamic equilibrium is established
with defect dipoles in parallel and anti-parallel orientation relative to the
spontaneous polarization. This process can be related to the deaging behavior
of piezoelectric ceramics.