title:
The 0.5-2.22-micron Scattered Light Spectrum of the Disk Around TW Hya:
  Detection of a Partially Filled Disk Gap at 80 AU

abstract:
  We present a 0.5-2.2 micron scattered light spectrum of the circumstellar
disk around TW Hya from a combination of spatially resolved HST STIS
spectroscopy and NICMOS coronagraphic images of the disk. We investigate the
morphology of the disk at distances > 40 AU over this wide range of
wavelengths, and identify the presence of a depression in surface brightness at
~80 AU that could be caused by a gap in the disk. Additionally, we quantify the
surface brightness, azimuthal symmetry, and spectral character of the disk as a
function of radius. Our analysis shows that the scattering efficiency of the
dust is largely neutral to blue over the observed wavelengths. We model the
disk as a steady alpha-disk with an ad hoc gap structure. The thermal
properties of the disk are self-consistently calculated using a
three-dimensional radiative transfer code that uses ray-tracing to model the
heating of the disk interior and scattered light images. We find a good fit to
the data over a wide range of distances from the star if we use a model disk
with a partially filled gap of 30% depth at 80 AU and with a self-similar
truncation knee at 100 AU. The origin of the gap is unclear, but it could arise
from a transition in the nature of the disk's dust composition or the presence
of a planetary companion. Based on scalings to previous hydrodynamic
simulations of gap opening criteria for embedded proto-planets, we estimate
that a planetary companion forming the gap could have a mass between 6-28
M_Earth.


title: Doubled \alpha'-Geometry

abstract:
  We develop doubled-coordinate field theory to determine the \alpha'
corrections to the massless sector of oriented bosonic closed string theory.
Our key tool is a string current algebra of free left-handed bosons that makes
O(D,D) T-duality manifest. While T-dualities are unchanged, diffeomorphisms and
b-field gauge transformations receive corrections, with a gauge algebra given
by an \alpha'-deformation of the duality-covariantized Courant bracket. The
action is cubic in a double metric field, an unconstrained extension of the
generalized metric that encodes the gravitational fields. Our approach provides
a consistent truncation of string theory to massless fields with corrections
that close at finite order in \alpha'.


title: Reionization Histories of Milky Way Mass Halos

abstract:
  We investigate the connection between the epoch of reionization and the
present day universe, by examining the extended mass reionization histories of
dark matter halos identified at z=0. We combine an N-body dark matter
simulation of a 600 Mpc volume with a three-dimensional, seminumerical
reionization model. This provides reionization redshifts for each particle,
which can then be connected with the properties of their halos at the present
time. We find that the vast majority of present-day halos with masses larger
than ~ few x 10^11 Msun reionize earlier than the rest of the universe. We also
find significant halo-to-halo diversity in mass reionization histories, and
find that in realistic inhomogenous models, the material within a given halo is
not expected to reionize at the same time. In particular, the scatter in
reionization times within individual halos is typically larger than the scatter
among halos. From our fiducial reionization model, we find that the typical 68%
scatter in reionization times within halos is ~ 115 Myr for 10^(12 \pm 0.25)
Msun halos, decreasing slightly to ~ 95 Myr for 10^(15 \pm 0.25) Msun halos. We
find a mild correlation between reionization history and environment: halos
with shorter reionization histories are typically in more clustered
environments, with the strongest trend on a scale of ~ 20 Mpc. Material in
Milky Way mass halos with short reionization histories is preferentially
reionized in relatively large HII regions, implying reionization mostly by
sources external to the progenitors of the present-day halo. We investigate the
impact on our results of varying the reionization model parameters, which span
a range of reionization scenarios with varying timing and morphology.


title:
Synchronization-Aware and Algorithm-Efficient Chance Constrained Optimal
  Power Flow

abstract:
  One of the most common control decisions faced by power system operators is
the question of how to dispatch generation to meet demand for power. This is a
complex optimization problem that includes many nonlinear, non convex
constraints as well as inherent uncertainties about future demand for power and
available generation. In this paper we develop convex formulations to
appropriately model crucial classes of nonlinearities and stochastic effects.
We focus on solving a nonlinear optimal power flow (OPF) problem that includes
loss of synchrony constraints and models wind-farm caused fluctuations. In
particular, we develop (a) a convex formulation of the deterministic
phase-difference nonlinear Optimum Power Flow (OPF) problem; and (b) a
probabilistic chance constrained OPF for angular stability, thermal overloads
and generation limits that is computationally tractable.


title: Finesse, Frequency domain INterferomEter Simulation SoftwarE

abstract:
  Finesse is a fast interferometer simulation program. For a given optical
setup, it computes the light field amplitudes at every point in the
interferometer assuming a steady state. To do so, the interferometer
description is translated into a set of linear equations that are solved
numerically. For convenience, a number of standard analyses can be performed
automatically by the program, namely computing modulation-demodulation error
signals, transfer functions, shot-noise-limited sensitivities, and beam shapes.
Finesse can perform the analysis using the plane-wave approximation or
Hermite-Gauss modes. The latter allows computation of the properties of optical
systems like telescopes and the effects of mode matching and mirror angular
positions.


title:
Stellar Diameters and Temperatures III. Main Sequence A, F, G, & K
  Stars: Additional high-precision measurements and empirical relations

abstract:
  Based on CHARA Array measurements, we present the angular diameters of 23
nearby, main- sequence stars, ranging from spectral type A7 to K0, five of
which are exoplanet host stars. We derive linear radii, effective temperatures,
and absolute luminosities of the stars using HIPPARCOS parallaxes and measured
bolometric fluxes. The new data are combined with previously published values
to create an Angular Diameter Anthology of measured angular diameters to
main-sequence stars (luminosity class V and IV). This compilation consists of
125 stars with diameter uncertainties of less than 5%, ranging in spectral
types from A to M. The large quantity of empirical data are used to derive
color-temperature relations to an assortment of color indices in the Johnson
(BVRIJHK), Cousins (RI), Kron (RI), Sloan (griz), and WISE (W3W4) photometric
systems. These relations have an average standard deviation of ~3% and are
valid for stars with spectral types A0 to M4. To derive even more accurate
relations for Sun-like stars, we also determined these temperature relations
omitting early-type stars (Teff > 6750 K) that may have biased luminosity
estimates because of rapid rotation; for this subset the dispersion is only
~2.5%. We find effective temperatures in agreement within a couple percent for
the interferometrically characterized sample of main sequence stars compared to
those derived via the infrared-flux method and spectroscopic analysis.


title:
Construction of an effective Yang-Mills Lagrangian with manifest BCJ
  duality

abstract:
  The BCJ decomposition is a highly non-trivial property of gauge theories. In
this paper we systematically construct an effective Lagrangian, whose Feynman
rules automatically produce the BCJ numerators. The effective Lagrangian
contains non-local terms. The difference between the standard Yang-Mills
Lagrangian and the effective Lagrangian simplifies to zero.


title:
Seshadri constants, Diophantine approximation, and Roth's Theorem for
  arbitrary varieties

abstract:
  In this paper, we associate an invariant $\alpha_{x}(L)$ to an algebraic
point $x$ on an algebraic variety $X$ with an ample line bundle $L$. The
invariant $\alpha$ measures how well $x$ can be approximated by rational points
on $X$, with respect to the height function associated to $L$. We show that
this invariant is closely related to the Seshadri constant $\epsilon_{x}(L)$
measuring local positivity of $L$ at $x$, and in particular that Roth's theorem
on $\mathbf{P}^1$ generalizes as an inequality between these two invariants
valid for arbitrary projective varieties.


title: An analogue of Liouville's Theorem and an application to cubic surfaces

abstract:
  We prove a strong analogue of Liouville's Theorem in Diophantine
approximation for points on arbitrary algebraic varieties. We use this theorem
to prove a conjecture of the first author for cubic surfaces in $\P^3$.


title: Graphs with Plane Outside-Obstacle Representations

abstract:
  An \emph{obstacle representation} of a graph consists of a set of polygonal
obstacles and a distinct point for each vertex such that two points see each
other if and only if the corresponding vertices are adjacent. Obstacle
representations are a recent generalization of classical polygon--vertex
visibility graphs, for which the characterization and recognition problems are
long-standing open questions.
  In this paper, we study \emph{plane outside-obstacle representations}, where
all obstacles lie in the unbounded face of the representation and no two
visibility segments cross. We give a combinatorial characterization of the
biconnected graphs that admit such a representation. Based on this
characterization, we present a simple linear-time recognition algorithm for
these graphs. As a side result, we show that the plane vertex--polygon
visibility graphs are exactly the maximal outerplanar graphs and that every
chordal outerplanar graph has an outside-obstacle representation.


title: Completing Any Low-rank Matrix, Provably

abstract:
  Matrix completion, i.e., the exact and provable recovery of a low-rank matrix
from a small subset of its elements, is currently only known to be possible if
the matrix satisfies a restrictive structural constraint---known as {\em
incoherence}---on its row and column spaces. In these cases, the subset of
elements is sampled uniformly at random.
  In this paper, we show that {\em any} rank-$ r $ $ n$-by-$ n $ matrix can be
exactly recovered from as few as $O(nr \log^2 n)$ randomly chosen elements,
provided this random choice is made according to a {\em specific biased
distribution}: the probability of any element being sampled should be
proportional to the sum of the leverage scores of the corresponding row, and
column. Perhaps equally important, we show that this specific form of sampling
is nearly necessary, in a natural precise sense; this implies that other
perhaps more intuitive sampling schemes fail.
  We further establish three ways to use the above result for the setting when
leverage scores are not known \textit{a priori}: (a) a sampling strategy for
the case when only one of the row or column spaces are incoherent, (b) a
two-phase sampling procedure for general matrices that first samples to
estimate leverage scores followed by sampling for exact recovery, and (c) an
analysis showing the advantages of weighted nuclear/trace-norm minimization
over the vanilla un-weighted formulation for the case of non-uniform sampling.


title:
Positivity conjectures for Kazhdan-Lusztig theory on twisted
  involutions: the finite case

abstract:
  Let $(W,S)$ be any Coxeter system and let $w \mapsto w^*$ be an involution of
$W$ which preserves the set of simple generators $S$. Lusztig and Vogan have
shown that the corresponding set of twisted involutions (i.e., elements $w \in
W$ with $w^{-1} = w^*$) naturally generates a module of the Hecke algebra of
$(W,S)$ with two distinguished bases. The transition matrix between these bases
defines a family of polynomials $P^\sigma_{y,w}$ which one can view as a
"twisted" analogue of the much-studied family of Kazhdan-Lusztig polynomials of
$(W,S)$. The polynomials $P^\sigma_{y,w}$ can have negative coefficients, but
display several conjectural positivity properties of interest, which parallel
positivity properties of the Kazhdan-Lusztig polynomials. This paper reports on
some calculations which verify four such positivity conjectures in several
finite cases of interest, in particular for the non-crystallographic Coxeter
systems of types $H_3$ and $H_4$.


title: Estimating the uncertainty in underresolved nonlinear dynamics

abstract:
  The Mori-Zwanzig formalism of statistical mechanics is used to estimate the
uncertainty caused by underresolution in the solution of a nonlinear dynamical
system. A general approach is outlined and applied to a simple example. The
noise term that describes the uncertainty turns out to be neither Markovian nor
Gaussian. It is argued that this is the general situation.


title:
Enhancing infrared extinction and absorption in a monolayer graphene
  sheet by harvesting the electric dipolar mode of split ring resonators

abstract:
  Optical extinction and absorption enhancement in the infrared range of a
monolayer graphene sheet by patterning split ring resonators (SRRs) is studied.
It is found that the electric mode is stronger in enhancing infrared extinction
and absorption compared to the magnetic mode and other higher-order modes. We
improve the infrared extinction of the SRR graphene sheet by increasing the
graphene area ratio in the SRR unit cell design. With the increase of the
graphene area ratio, the radiation ability of the electric dipolar mode and
dissipation of graphene compete for a maximum infrared absorption of about 50%.
The findings on enhancing infrared extinction and absorption of graphene sheet
by harvesting the electric dipolar mode may have potential applications in
terahertz and infrared detection and modulation for graphene photonics and
optoelectronics.


title: Lifetimes and Lengthscales of Structural Motifs in a Model Glassformer

abstract:
  We use a newly-developed method to identify local structural motifs in a
popular model glassformer, the Kob-Andersen binary Lennard-Jones mixture. By
measuring the lifetimes of a zoo of clusters, we find that 11-membered bicapped
square antiprisms, denoted as 11A, have longer lifetimes on average than other
structures considered. Other long-lived clusters are similar in structure to
the 11A cluster. These clusters group into ramified networks that are
correlated with slow particles and act to retard the motion of neighbouring
particles. The structural lengthscale associated with these networks does not
grow as fast as the dynamical lengthscale $\xi_4$ as the system is cooled, in
the range of temperatures our molecular dynamics simulations access. Thus we
find a strong, but indirect, correlation between static structural ordering and
slow dynamics.


title: Toda lattice G-Strands

abstract:
  Hamilton's principle is used to extend for the Toda lattice ODEs to systems
of PDEs called the Toda lattice strand equations (T-Strands). The T-Strands in
the $n$-particle Toda case comprise $4n-2$ quadratically nonlinear PDEs in one
space and one time variable. T-Strands form a symmetric hyperbolic Lie-Poisson
Hamiltonian system of quadratically nonlinear PDEs with constant characteristic
velocities. The travelling wave solutions for the two-particle T-Strand
equations are solved geometrically, and their Lax pair is given to show how
nonlinearity affects the solution. The three-particle T-Strands equations are
also derived from Hamilton's principle. For both the two-particle and
three-particle T-Strand PDEs the determining conditions for the existence of a
quadratic zero-curvature relation (ZCR) exactly cancel the nonlinear terms in
the PDEs. Thus, the two-particle and three-particle T-Strand PDEs do not pass
the ZCR test for integrability.


title: Tarski Measure

abstract:
  We present an approach to the study of stationary measures placing Tarski's
foundational work in this area within a modern category theoretic context.
Guiding this work is the notion that measurable spaces equipped with symmetries
carry an intrinsic notion of `size'. We demonstrate that within such measurable
spaces, the collection of these sizes embeds into a partially ordered
commutative inverse monoid. Using this we prove, in great generality, the basic
theorems of measure theory and give an algebraic characterization of the space
of classical real valued stationary measures.


title:
Implications of mixed axion/neutralino dark matter for the Cosmic
  Frontier: a Snowmass whitepaper

abstract:
  If one simultaneously invokes the SUSY solution to the gauge hierarchy
problem and the PQ solution to the strong CP problem, then one might expect
mixed axion/neutralino dark matter (DM), i.e. two dark matter particles. In
this case, dark matter production involves oscillation production of axions,
thermal and non-thermal neutralino production and thermal and non-thermal
production of axinos and saxions. The latter particles may feed additional
neutralinos into the cosmic soup, or dilute all relics via additional entropy
production, or feed dark radiation into the cosmos. Depending on the SUSY and
PQ model, the PQ scale can easily exist from 10^9-10^{16} GeV. Axions may lie
well beyond the range currently being probed by experiment. In the case of
relic WIMPs, theoretical predictions must be rescaled for the possibility that
WIMPs only comprise a fraction of the local DM abundance.


title: Coarse graining of spin net models: dynamics of intertwiners

abstract:
  Spin foams are models of quantum gravity and therefore quantum space time. A
key open issue is to determine the possible continuum phases of these models.
Progress on this issue has been prohibited by the complexity of the full
four--dimensional models. We consider here simplified analogue models, so
called spin nets, that retain the main dynamical ingredient of spin foams, the
simplicity constraints. For a certain class of these spin net models we
determine the phase diagram and therefore the continuum phases via a coarse
graining procedure based on tensor network renormalization. This procedure will
also reveal an unexpected fixed point, which turns out to define a new
triangulation invariant vertex model.


title: Matching with our Eyes Closed

abstract:
  Motivated by an application in kidney exchange, we study the following
query-commit problem: we are given the set of vertices of a non-bipartite graph
G. The set of edges in this graph are not known ahead of time. We can query any
pair of vertices to determine if they are adjacent. If the queried edge exists,
we are committed to match the two endpoints. Our objective is to maximize the
size of the matching.
  This restriction in the amount of information available to the algorithm
constraints us to implement myopic, greedy-like algorithms. A simple
deterministic greedy algorithm achieves a factor 1/2 which is tight for
deterministic algorithms. An important open question in this direction is to
give a randomized greedy algorithm that has a significantly better
approximation factor. This question was first asked almost 20 years ago by Dyer
and Frieze [9] where they showed that a natural randomized strategy of picking
edges uniformly at random doesn't help and has an approximation factor of 1/2 +
o(1). They left it as an open question to devise a better randomized greedy
algorithm. In subsequent work, Aronson, Dyer, Frieze, and Suen [2] gave a
different randomized greedy algorithm and showed that it attains a factor 0.5 +
epsilon where epsilon is 0.0000025.
  In this paper we propose and analyze a new randomized greedy algorithm for
finding a large matching in a general graph and use it to solve the query
commit problem mentioned above. We show that our algorithm attains a factor of
at least 0.56, a significant improvement over 0.50000025. We also show that no
randomized algorithm can have an approximation factor better than 0.7916 for
the query commit problem. For another large and interesting class of randomized
algorithms that we call vertex-iterative algorithms, we show that no
vertex-iterative algorithm can have an approximation factor better than 0.75.


title:
On D\"umbgen's exponentially modified Laplace continued fraction for
  Mill's ratio

abstract:
  The approximation of the Gaussian cumulative distribution or of the related
Mills ratio have a long history starting with Gauss and Laplace and continuing
nowadays. Below, we improve an important family of bounds provided recently by
D\"umbgen.


title: First Passage in Conical Geometry and Ordering of Brownian Particles

abstract:
  We survey recent results on first-passage processes in unbounded cones and
their applications to ordering of particles undergoing Brownian motion in one
dimension. We first discuss the survival probability S(t) that a diffusing
particle, in arbitrary spatial dimension, remains inside a conical domain up to
time t. In general, this quantity decays algebraically S ~ t^{-beta} in the
long-time limit. The exponent beta depends on the opening angle of the cone and
the spatial dimension, and it is root of a transcendental equation involving
the associated Legendre functions. The exponent becomes a function of a single
scaling variable in the limit of large spatial dimension. We then describe two
first-passage problems involving the order of N independent Brownian particles
in one dimension where survival probabilities decay algebraically as well. To
analyze these problems, we identify the trajectories of the N particles with
the trajectory of one particle in N dimensions, confined to within a certain
boundary, and we use a circular cone with matching solid angle as a replacement
for the confining boundary. For N=3, the confining boundary is a wedge and the
approach is exact. In general, this "cone approximation" gives strict lower
bounds as well as useful estimates or the first-passage exponents.
Interestingly, the cone approximation becomes asymptotically exact when
N-->infinity as it predicts the exact scaling function that governs the
spectrum of first-passage exponents.


title:
The Strength of the Weak: The Uncertainty Principle and More-Direct
  Access to the Wave Function through Weak Measurements

abstract:
  Recent empirical work in the field of 'weak measurements' has yielded novel
ways of more directly accessing and exploring the quantum wavefunction.
Measuring either position or momentum for a photon in a 'weak' manner yields a
wide range of possible values for the measurement, and can be done in such a
way as to only minimally effect the wavefunction rather than to collapse it to
a specific precise value. Measuring the other complementary variable (position
or momentum) precisely at a later time ('post-selection') and averaging the
weak measurements can yield information about the wavefunction that is not
directly experimentally obtainable using other methods. This paper discusses
two recent papers on weak measurement in the context of the uncertainty
principle more broadly, and considers some possibilities for further research.


title:
Higher order statistics of curvature perturbations in IFF model and its
  Planck constraints

abstract:
  We compute the power spectrum P_\zeta, and non-linear parameters f_nl and
\tau_nl of the curvature perturbation induced during inflation by the
electromagnetic fields in the kinetic coupling model (IFF model). By using the
observational result of P_\zeta, f_nl and \tau_nl reported by the Planck
collaboration, we study the constraint on the model comprehensively.
Interestingly, if the single slow-rolling inflaton is responsible for the
observed P_\zeta, the constraint from \tau_nl is most stringent. We also find a
general relationship between f_nl and \tau_nl generated in this model. Even if
f_nl \sim O(1), a detectable \tau_nl can be produced.


title:
Derivation of quantum mechanics from a single fundamental modification
  of the relations between physical properties

abstract:
  Recent results obtained in quantum measurements indicate that the fundamental
relations between three physical properties of a system can be represented by
complex conditional probabilities. Here, it is shown that these relations
provide a fully deterministic and universally valid framework on which all of
quantum mechanics can be based. Specifically, quantum mechanics can be derived
by combining the rules of Bayesian probability theory with only a single
additional law that explains the phases of complex probabilities. This law,
which I introduce here as the law of quantum ergodicity, is based on the
observation that the reality of physical properties cannot be separated from
the dynamics by which they emerge in measurement interactions. The complex
phases are an expression of this inseparability and represent the dynamical
structure of transformations between the different properties. In its
quantitative form, the law of quantum ergodicity describes a fundamental
relation between the ergodic probabilities obtained by dynamical averaging and
the deterministic relations between three properties expressed by the complex
conditional probabilities. The complete formalism of quantum mechanics can be
derived from this one relation, without any axiomatic mathematical assumptions
about state vectors or superpositions. It is therefore possible to explain all
quantum phenomena as the consequence of a single fundamental law of physics.


title:
Overcoming Si3N4 film stress limitations for High Quality factor ring
  resonators

abstract:
  Silicon nitride (Si3N4) ring resonators are critical for a variety of
photonic devices. However the intrinsically high film stress of silicon nitride
has limited both the optical confinement and quality factor (Q) of ring
resonators. We show that stress in Si3N4 films can be overcome by introducing
mechanical trenches for isolating photonic devices from propagating cracks. We
demonstrate a Si3N4 ring resonator with an intrinsic quality factor of 7
million, corresponding to a propagation loss of 4.2 dB/m. This is the highest
quality factor reported to date for high confinement Si3N4 ring resonators in
the 1550 nm wavelength range.


title: Boundary rigidity with partial data

abstract:
  We study the boundary rigidity problem with partial data consisting of
determining locally the Riemannian metric of a Riemannian manifold with
boundary from the distance function measured at pairs of points near a fixed
point on the boundary. We show that one can recover uniquely and in a stable
way a conformal factor near a strictly convex point where we have the
information. In particular, this implies that we can determine locally the
isotropic sound speed of a medium by measuring the travel times of waves
joining points close to a convex point on the boundary.
  The local results lead to a global lens rigidity uniqueness and stability
result assuming that the manifold is foliated by strictly convex hypersurfaces.


title:
A Five Dimensional Perspective on Many Particles in the Snyder basis of
  Double Special Relativity

abstract:
  After a brief summary of Double Special Relativity (DSR), we concentrate on a
five dimensional procedure, which consistently introduce coordinates and
momenta in the corresponding four-dimensional phase space, via a Hamiltonian
approach. For the one particle case, the starting point is a de Sitter momentum
space in five dimensions, with an additional constraint selected to recover the
mass shell condition in four dimensions. Different basis of DSR can be
recovered by selecting specific gauges to define the reduced four dimensional
degrees of freedom. This is shown for the Snyder basis in the one particle
case. We generalize the method to the many particles case and apply it again to
this basis. We show that the energy and momentum of the system, given by the
dynamical variables that are generators of translations in space and time and
which close the Poincar\'e algebra, are additive magnitudes. From this it
results that the rest energy (mass) of a composite object does not have an
upper limit, as opposed to a single component particle which does.


title: Phase-Field Crystal Model with a Vapor Phase

abstract:
  Phase-Field Crystal (PFC) models are able to resolve atomic length scale
features of materials during temporal evolution over diffusive time scales.
Traditional PFC models contain solid and liquid phases, however many important
materials processing phenomena involve a vapor phase as well. In this work, we
add a vapor phase to an existing PFC model and show realistic interfacial
phenomena near the triple point temperature. For example, the PFC model
exhibits density oscillations at liquid-vapor interfaces that compare favorably
to data available for interfaces in metallic systems from both experiment and
molecular dynamics simulations. We also quantify the anisotropic solid-vapor
surface energy for a 2D PFC hexagonal crystal and find well defined step
energies from measurements on the faceted interfaces. Additionally, the strain
field beneath a stepped interface is characterized and shown to qualitatively
reproduce predictions from continuum models, simulations, and experimental
data. Finally, we examine the dynamic case of step-flow growth of a crystal
into a supersaturated vapor phase. The ability to model such a wide range of
surface and bulk defects makes this PFC model a useful tool to study processing
techniques such as Chemical Vapor Deposition or Vapor-Liquid-Solid growth of
nanowires.


title: Constructing New Realisable Lists from Old in the NIEP

abstract:
  Given a list of complex numbers \sigma:=(\lambda_1,\lambda_2,...,\lambda_m),
we say that {\sigma} is realisable if {\sigma} is the spectrum of some
(entrywise) nonnegative matrix. The Nonnegative Inverse Eigenvalue Problem (or
NIEP) is the problem of categorising all realisable lists.
  Given a realisable list (\rho,\lambda_2,\lambda_3,...,\lambda_m), where
{\rho} is the Perron eigenvalue and \lambda_2 is real, we find families of
lists (\mu_1,\mu_2,...,\mu_n), for which
(\mu_1,\mu_2,...,\mu_n,\lambda_3,\lambda_4,...,\lambda_m) is realisable.
  In addition, given a realisable list
(\rho,\alpha+i\beta,\alpha-i\beta,\lambda_4,\lambda_5,...,\lambda_m), where
{\rho} is the Perron eigenvalue and {\alpha} and {\beta} are real, we find
families of lists (\mu_1,\mu_2,\mu_3,\mu_4), for which
(\mu_1,\mu_2,\mu_3,\mu_4,\lambda_4,\lambda_5,...,\lambda_m) is realisable.


title: Dynamic Infinite Mixed-Membership Stochastic Blockmodel

abstract:
  Directional and pairwise measurements are often used to model
inter-relationships in a social network setting. The Mixed-Membership
Stochastic Blockmodel (MMSB) was a seminal work in this area, and many of its
capabilities were extended since then. In this paper, we propose the
\emph{Dynamic Infinite Mixed-Membership stochastic blockModel (DIM3)}, a
generalised framework that extends the existing work to a potentially infinite
number of communities and mixture memberships for each of the network's nodes.
This model is in a dynamic setting, where additional model parameters are
introduced to reflect the degree of persistence between one's memberships at
consecutive times. Accordingly, two effective posterior sampling strategies and
their results are presented using both synthetic and real data.


title: Cole's Parametric Search Technique Made Practical

abstract:
  Parametric search has been widely used in geometric algorithms. Cole's
improvement provides a way of saving a logarithmic factor in the running time
over what is achievable using the standard method. Unfortunately, this
improvement comes at the expense of making an already complicated algorithm
even more complex; hence, this technique has been mostly of theoretical
interest. In this paper, we provide an algorithm engineering framework that
allows for the same asymptotic complexity to be achieved probabilistically in a
way that is both simple and practical (i.e., suitable for actual
implementation). The main idea of our approach is to show that a variant of
quicksort, known as boxsort, can be used to drive comparisons, instead of using
a sorting network, like the complicated AKS network, or an EREW parallel
sorting algorithm, like the fairly intricate parallel mergesort algorithm. This
results in a randomized optimization algorithm with a running time matching
that of using Cole's method, with high probability, while also being practical.
We show how this results in practical implementations of some geometric
algorithms utilizing parametric searching and provide experimental results that
prove practicality of the method.


title: On the spectra of fermionic second quantization operators

abstract:
  We derive several formulae for the spectra of the second quantization
operators in abstract fermionic Fock spaces.


title: A Convergence Theorem for the Graph Shift-type Algorithms

abstract:
  Graph Shift (GS) algorithms are recently focused as a promising approach for
discovering dense subgraphs in noisy data. However, there are no theoretical
foundations for proving the convergence of the GS Algorithm. In this paper, we
propose a generic theoretical framework consisting of three key GS components:
simplex of generated sequence set, monotonic and continuous objective function
and closed mapping. We prove that GS algorithms with such components can be
transformed to fit the Zangwill's convergence theorem, and the sequence set
generated by the GS procedures always terminates at a local maximum, or at
worst, contains a subsequence which converges to a local maximum of the
similarity measure function. The framework is verified by expanding it to other
GS-type algorithms and experimental results.


title: Non-parametric Power-law Data Clustering

abstract:
  It has always been a great challenge for clustering algorithms to
automatically determine the cluster numbers according to the distribution of
datasets. Several approaches have been proposed to address this issue,
including the recent promising work which incorporate Bayesian Nonparametrics
into the $k$-means clustering procedure. This approach shows simplicity in
implementation and solidity in theory, while it also provides a feasible way to
inference in large scale datasets. However, several problems remains unsolved
in this pioneering work, including the power-law data applicability, mechanism
to merge centers to avoid the over-fitting problem, clustering order problem,
e.t.c.. To address these issues, the Pitman-Yor Process based k-means (namely
\emph{pyp-means}) is proposed in this paper. Taking advantage of the Pitman-Yor
Process, \emph{pyp-means} treats clusters differently by dynamically and
adaptively changing the threshold to guarantee the generation of power-law
clustering results. Also, one center agglomeration procedure is integrated into
the implementation to be able to merge small but close clusters and then
adaptively determine the cluster number. With more discussion on the clustering
order, the convergence proof, complexity analysis and extension to spectral
clustering, our approach is compared with traditional clustering algorithm and
variational inference methods. The advantages and properties of pyp-means are
validated by experiments on both synthetic datasets and real world datasets.


title: Pseudorandomness for Regular Branching Programs via Fourier Analysis

abstract:
  We present an explicit pseudorandom generator for oblivious, read-once,
permutation branching programs of constant width that can read their input bits
in any order. The seed length is $O(\log^2 n)$, where $n$ is the length of the
branching program. The previous best seed length known for this model was
$n^{1/2+o(1)}$, which follows as a special case of a generator due to
Impagliazzo, Meka, and Zuckerman (FOCS 2012) (which gives a seed length of
$s^{1/2+o(1)}$ for arbitrary branching programs of size $s$). Our techniques
also give seed length $n^{1/2+o(1)}$ for general oblivious, read-once branching
programs of width $2^{n^{o(1)}}$, which is incomparable to the results of
Impagliazzo et al.Our pseudorandom generator is similar to the one used by
Gopalan et al. (FOCS 2012) for read-once CNFs, but the analysis is quite
different; ours is based on Fourier analysis of branching programs. In
particular, we show that an oblivious, read-once, regular branching program of
width $w$ has Fourier mass at most $(2w^2)^k$ at level $k$, independent of the
length of the program.


title:
An Optimization Method of Asymmetric Resonant Cavities for
  Unidirectional Emission

abstract:
  In this paper, we studied the repeatability and accuracy of the ray
simulation for one kind of Asymmetric Resonant Cavities (ARCs)
Half-Quadrupole-Half-Circle shaped cavity, and confirmed the robustness of the
directionality about the shape errors. Based on these, we proposed a
hill-climbing algorithm to optimize the ARCs for unidirectional emission.
Different evaluation functions of directionality were tested and we suggested
using the function of energy contained in a certain angle for highly collimated
and unidirect ional emission. By this method, we optimized the ARCs to obtain
about 0.46 of the total radiated energy in divergence angle of 40 degree in the
far field. This optimization method is very powerful for the shape engineering
of ARCs and could be applied in future studies of ARCs with specific emission
properties.


title:
Possible High-Energy Neutrino and Photon Signals from Gravitational Wave
  Bursts due to Double Neutron Star Mergers

abstract:
  As the technology of gravitational-wave and neutrino detectors becomes
increasingly mature, a multi-messenger era of astronomy is ushered in. Advanced
gravitational wave detectors are close to making a ground-breaking discovery of
gravitational wave bursts (GWBs) associated with mergers of double neutron
stars (NS-NS). It is essential to study the possible electromagnetic (EM) and
neutrino emission counterparts of these GWBs. Recent observations and numerical
simulations suggest that at least a fraction of NS-NS mergers may leave behind
a massive millisecond magnetar as the merger product. Here we show that protons
accelerated in the forward shock powered by a magnetar wind pushing the ejecta
launched during the merger process would interact with photons generated in the
dissipating magnetar wind and emit high energy neutrinos and photons. We
estimate the typical energy and fluence of the neutrinos from such a scenario.
We find that $\sim$PeV neutrinos could be emitted from the shock front as long
as the ejecta could be accelerated to a relativistic speed. The diffuse
neutrino flux from these events, even under the most optimistic scenarios, is
too low to account for the two events announced by the IceCube Collaboration,
but it is only slightly lower than the diffuse flux of GRBs, making it an
important candidate for the diffuse background of $\sim$PeV neutrinos. The
neutron-pion decay of these events make them a moderate contributor to the
sub-TeV gamma-ray diffuse background.


title:
Robustness of cooperation on scale-free networks under continuous
  topological change

abstract:
  In this paper, we numerically investigate the robustness of cooperation
clusters in prisoner's dilemma played on scale-free networks, where the network
topologies change by continuous removal and addition of nodes. Each removal and
addition can be either random or intentional. We therefore have four different
strategies in changing network topology: random removal and random addition
(RR), random removal and preferential addition (RP), targeted removal and
random addition (TR), and targeted removal and preferential addition (TP). We
find that cooperation clusters are most fragile against TR, while they are most
robust against RP, even for large values of the temptation coefficient for
defection. The effect of the degree mixing pattern of the network is not the
primary factor for the robustness of cooperation under continuous change in
network topology, which is quite different from the cases observed in static
networks. Cooperation clusters become more robust as the number of links of
hubs occupied by cooperators increase. Our results might infer the fact that a
huge variety of individuals is needed for maintaining global cooperation in
social networks in the real world where each node representing an individual is
constantly removed and added.


title: Large-gap quantum spin Hall insulators in tin films

abstract:
  The search of large-gap quantum spin Hall (QSH) insulators and effective
approaches to tune QSH states is important for both fundamental and practical
interests. Based on first-principles calculations we find two-dimensional tin
films are QSH insulators with sizable bulk gaps of 0.3 eV, sufficiently large
for practical applications at room temperature. These QSH states can be
effectively tuned by chemical functionalization and by external strain. The
mechanism for the QSH effect in this system is band inversion at the \Gamma
point, similar to the case of HgTe quantum well. With surface doping of
magnetic elements, the quantum anomalous Hall effect could also be realized.


title:
Probe of the Solar Magnetic Field Using the "Cosmic-Ray Shadow" of the
  Sun

abstract:
  We report on a clear solar-cycle variation of the Sun's shadow in the 10 TeV
cosmic-ray flux observed by the Tibet air shower array during a full solar
cycle from 1996 to 2009. In order to clarify the physical implications of the
observed solar cycle variation, we develop numerical simulations of the Sun's
shadow, using the Potential Field Source Surface (PFSS) model and the Current
Sheet Source Surface (CSSS) model for the coronal magnetic field. We find that
the intensity deficit in the simulated Sun's shadow is very sensitive to the
coronal magnetic field structure, and the observed variation of the Sun's
shadow is better reproduced by the CSSS model. This is the first successful
attempt to evaluate the coronal magnetic field models by using the Sun's shadow
observed in the TeV cosmic-ray flux.


title:
Phase transitions in Ising model induced by weight redistribution on
  weighted regular networks

abstract:
  In order to investigate the role of the weight in weighted networks, the
collective behavior of the Ising system on weighted regular networks is studied
by numerical simulation. In our model, the coupling strength between spins is
inversely proportional to the corresponding weighted shortest distance.
Disordering link weights can effectively affect the process of phase transition
even though the underlying binary topological structure remains unchanged.
Specifically, based on regular networks with homogeneous weights initially,
randomly disordering link weights will change the critical temperature of phase
transition. The results suggest that the redistribution of link weights may
provide an additional approach to optimize the dynamical behaviors of the
system.


title:
Proximity-Aware Calculation of Cable Series Impedance for Systems of
  Solid and Hollow Conductors

abstract:
  Wide-band cable models for the prediction of electromagnetic transients in
power systems require the accurate calculation of the cable series impedance as
function of frequency. A surface current approach was recently proposed for
systems of round solid conductors, with inclusion of skin and proximity
effects. In this paper we extend the approach to include tubular conductors,
allowing to model realistic cables with tubular sheaths, armors and pipes. We
also include the effect of a lossy ground. A noteworthy feature of the proposed
technique is the accurate prediction of proximity effects, which can be of
major importance in three-phase, pipe type, and closely-packed single-core
cables. The new approach is highly efficient compared to finite elements. In
the case of a cross-bonded cable system featuring three phase conductors and
three screens, the proposed technique computes the required 120 frequency
samples in only six seconds of CPU time.


title: Ionization toward the high-mass star-forming region NGC 6334 I

abstract:
  Context. Ionization plays a central role in the gas-phase chemistry of
molecular clouds. Since ions are coupled with magnetic fields, which can in
turn counteract gravitational collapse, it is of paramount importance to
measure their abundance in star-forming regions. Aims. We use spectral line
observations of the high-mass star-forming region NGC 6334 I to derive the
abundance of two of the most abundant molecular ions, HCO+ and N2H+, and
consequently, the cosmic ray ionization rate. In addition, the line profiles
provide information about the kinematics of this region. Methods. We present
high-resolution spectral line observations conducted with the HIFI instrument
on board the Herschel Space Observatory of the rotational transitions with Jup
> 5 of the molecular species C17O, C18O, HCO+, H13CO+, and N2H+. Results. The
HCO+ and N2H+ line profiles display a redshifted asymmetry consistent with a
region of expanding gas. We identify two emission components in the spectra,
each with a different excitation, associated with the envelope of NGC 6334 I.
The physical parameters obtained for the envelope are in agreement with
previous models of the radial structure of NGC 6334 I based on submillimeter
continuum observations. Based on our new Herschel/HIFI observations, combined
with the predictions from a chemical model, we derive a cosmic ray ionization
rate that is an order of magnitude higher than the canonical value of 10^(-17)
s-1. Conclusions. We find evidence of an expansion of the envelope surrounding
the hot core of NGC 6334 I, which is mainly driven by thermal pressure from the
hot ionized gas in the region. The ionization rate seems to be dominated by
cosmic rays originating from outside the source, although X-ray emission from
the NGC 6334 I core could contribute to the ionization in the inner part of the
envelope.


title:
Calculation of the staggered spin correlation in the framework of the
  Dyson-Schwinger approach

abstract:
  Based on the linear response of the fermion propagator with respect to an
external field, we first derive a model-independent expression for the
staggered spin susceptibility in which the influence of the full pseudoscalar
vertex function is included. This expression for the staggered spin
susceptibility is quite different from that given in the previous literature.
The numerical values of the staggered spin susceptibility are calculated within
the framework of the Dyson-Schwinger approach. Our numerical result shows that
the nonperturbative dressing effects on the fermion propagator is very
important when one studies the staggered spin susceptibility which
corresponding to antiferromagnetic correlation in both Nambu phase and Winger
phase.


title: Mixtures of Spatial Spline Regressions

abstract:
  We present an extension of the functional data analysis framework for
univariate functions to the analysis of surfaces: functions of two variables.
The spatial spline regression (SSR) approach developed can be used to model
surfaces that are sampled over a rectangular domain. Furthermore, combining SSR
with linear mixed effects models (LMM) allows for the analysis of populations
of surfaces, and combining the joint SSR-LMM method with finite mixture models
allows for the analysis of populations of surfaces with sub-family structures.
Through the mixtures of spatial splines regressions (MSSR) approach developed,
we present methodologies for clustering surfaces into sub-families, and for
performing surface-based discriminant analysis. The effectiveness of our
methodologies, as well as the modeling capabilities of the SSR model are
assessed through an application to handwritten character recognition.


title:
Biologically inspired graphene-chlorophyll phototransistors with high
  gain

abstract:
  We present prominent photoresponse of bio-inspired graphene-based
phototransistors sensitized with chlorophyll molecules. The hybrid
graphene-chlorophyll phototransistors exhibit a high gain of 10^6 electrons per
photon and a high responsivity of 10^6 A/W, which can be attributed to the
integration of high-mobility graphene and the photosensitive chlorophyll
molecules. The charge transfer at interface and the photogating effect in the
chlorophyll layer can account for the observed photoresponse of the hybrid
devices, which is confirmed by the back-gate-tunable photocurrent as well as
the thickness and time dependent studies of the photoresponse. The
demonstration of the graphene-chlorophyll phototransistors with high gain
envisions a viable method to employ biomaterials for graphene-based
optoelectronics.


title: Analysis of the Time Reversible Born-Oppenheimer Molecular Dynamics

abstract:
  We analyze the time reversible Born-Oppenheimer molecular dynamics (TRBOMD)
scheme, which preserves the time reversibility of the Born-Oppenheimer
molecular dynamics even with non-convergent self-consistent field iteration. In
the linear response regime, we derive the stability condition as well as the
accuracy of TRBOMD for computing physical properties such as the phonon
frequency obtained from the molecular dynamic simulation. We connect and
compare TRBOMD with the Car-Parrinello molecular dynamics in terms of accuracy
and stability. We further discuss the accuracy of TRBOMD beyond the linear
response regime for non-equilibrium dynamics of nuclei. Our results are
demonstrated through numerical experiments using a simplified one dimensional
model for Kohn-Sham density functional theory.


title:
Scale-free and power law distributions via fixed points and convergence
  of (thinning and conditioning) transformations

abstract:
  In discrete contexts such as the degree distribution for a graph,
\emph{scale-free} has traditionally been \emph{defined} to be \emph{power-law}.
We propose a reasonable interpretation of \emph{scale-free}, namely, invariance
under the transformation of $p$-thinning, followed by conditioning on being
positive.
  For each $\beta \in (1,2)$, we show that there is a unique distribution which
is a fixed point of this transformation; the distribution is power-law-$\beta$,
and different from the usual Yule--Simon power law-$\beta$ that arises in
preferential attachment models.
  In addition to characterizing these fixed points, we prove convergence
results for iterates of the transformation.


title: Second Order Swarm Intelligence

abstract:
  An artificial Ant Colony System (ACS) algorithm to solve general-purpose
combinatorial Optimization Problems (COP) that extends previous AC models [21]
by the inclusion of a negative pheromone, is here described. Several Travelling
Salesman Problem (TSP) were used as benchmark. We show that by using two
different sets of pheromones, a second-order co-evolved compromise between
positive and negative feedbacks achieves better results than single positive
feedback systems. The algorithm was tested against known NP-complete
combinatorial Optimization Problems, running on symmetrical TSP's. We show that
the new algorithm compares favourably against these benchmarks, accordingly to
recent biological findings by Robinson [26,27], and Gruter [28] where "No
entry" signals and negative feedback allows a colony to quickly reallocate the
majority of its foragers to superior food patches. This is the first time an
extended ACS algorithm is implemented with these successful characteristics.


title: A Renormalization Group Approach to A Yang-Mills Two Matrix Model

abstract:
  A Yang-Mills type two matrix model with mass terms is studied by use of a
matrix renormalization group approach proposed by Brezin and Zinn-Justin. The
renormalization group method indicates that the model exhibits a critical
behavior similar to that of two dimensional Euclidean gravity. A massless limit
and the generation of quadratic terms along the renormalization group flow are
discussed.


title: The geodesic motion near hypersurfaces in the warped products spacetime

abstract:
  In the framework of Lorentzian multiply warped products we study the
Gibbons-Maeda-Garfinkle-Horowitz-Strominger (GMGHS) spacetime near
hypersurfaces in the interior of the event horizon. We also investigate the
geodesic motion in hypersurfaces.


title: The Trace-Free Einstein Equations and inflation

abstract:
  The trace-free version of the Einstein Gravitational equations, essentially
equivalent to unimodular gravity, can solve the troubling issue of the huge
discrepancy between quantum field theory estimates of the vacuum energy density
and the astronomically observed value of the cosmological constant. However it
has been suggested that this proposal cannot work because it prevents the
inflaton potential energy from driving inflation. It is shown here that that
concern is unjustified: inflation proceeds as usual if we adopt the trace free
gravitational equations.


title:
On the Quark-Gluon Vertex and Quark-Ghost Kernel: combining Lattice
  Simulations with Dyson-Schwinger equations

abstract:
  We investigate the dressed quark-gluon vertex combining two established
non-perturbative approaches to QCD: the Dyson-Schwinger equation (DSE) for the
quark propagator and lattice-regularized simulations for the quark, gluon and
ghost propagators. The vertex is modeled using a generalized Ball-Chiu ansatz
parameterized by a single form factor $\tilde X_0$ which effectively represents
the quark-ghost scattering kernel. The solution space of the DSE inversion for
$\tilde X_0$ is highly degenerate, which can be dealt with by a numerical
regularization scheme. We consider two possibilities: (i) linear regularization
and (ii) the Maximum Entropy Method. These two numerical approaches yield
compatible $\tilde X_0$ functions for the range of momenta where lattice data
is available and feature a strong enhancement of the generalized Ball-Chiu
vertex for momenta below 1 GeV. Our ansatz for the quark-gluon vertex is then
used to solve the quark DSE which yields a mass function in good agreement with
lattice simulations and thus provides adequate dynamical chiral symmetry
breaking.


title: Waveguiding-assisted random lasing in epitaxial ZnO thin film

abstract:
  Zinc Oxide thin films were grown on c-sapphire substrates using pulsed laser
deposition. Pump power dependence of surface emission spectra, acquired using a
quadrupled 266 nm laser, revealed room temperature stimulated emission
(threshold of 900 kW/cm2). Time dependent spectral analysis plus gain
measurements of single-shot, side-emission, spectra pumped with a nitrogen
laser revealed random lasing indicative of the presence of self-forming laser
cavities. It is suggested that random lasing in an epitaxial system rather than
a 3-dimensional configuration of disordered scattering elements, was due to
waveguiding in the film. Waveguiding causes light to be amplified within
randomly-formed closed-loops acting as lasing cavities.


title: Combinatorial search of superconductivity in Fe-B composition spreads

abstract:
  We have fabricated Fe-B thin film composition spreads in search of possible
superconducting phases following a theoretical prediction by Kolmogorov et
al.^1 Co-sputtering was used to deposit spreads covering a large compositional
region of the Fe-B binary phase diagram. A trace of superconducting phase was
found in the nanocrystalline part of the spread, where the film undergoes a
metal to insulator transition as a function of composition in a region with the
average composition of FeB_2. The resistance drop occurs at 4K, and a
diamagnetic signal has also been detected at the same temperature. The
superconductivity is suppressible in the magnetic field up to 2 Tesla.


title: A Multidimensional Szemer\'edi Theorem in the primes

abstract:
  Let $A$ be a subset of positive relative upper density of $\PP^d$, the
$d$-tuples of primes. We prove that $A$ contains an affine copy of any finite
set $F\subs\Z^d$, which provides a natural multi-dimensional extension of the
theorem of Green and Tao on the existence of long arithmetic progressions in
the primes. The proof uses the hypergraph approach by assigning a pseudo-random
weight system to the pattern $F$ on a $d+1$-partite hypergraph; a novel feature
being that the hypergraph is no longer uniform with weights attached to lower
dimensional edges. Then, instead of using a transference principle, we proceed
by extending the proof of the so-called hypergraph removal lemma to our
settings, relying only on the linear forms condition of Green and Tao.


title: Corners in dense subsets of P^d

abstract:
  Let $\PP^d$ be the $d$-fold direct product of the set of primes. We prove
that if $A$ is a subset of $\PP^d$ of positive relative upper density then $A$
contains infinitely many "corners", that is sets of the form
$\{x,x+te_1,...,x+te_d\}$ where x is an integer point and e_1,...,e_d are the
standard basis vectors of the d-dimensional Euclidean space. Our argument is
based on proving a removal lemma for weighted uniform hypergraphs, where the
weight system is defined in terms of a pairwise linearly independent family of
linear forms.


title:
Clues on the rejuvenation of the S0 galaxy NGC 404 from the chemical
  abundance of its outer disk

abstract:
  The oxygen abundance of the outer disk of the nearby S0 galaxy NGC 404, a
prototypical early-type galaxy with extended star formation, has been derived
from the analysis of HII region spectra. The high mean value found,
12+log(O/H)=8.6 \pm 0.1, equivalent to approximately 80% of the solar value,
argues against both the previously proposed cold accretion and recent merger
scenarios as viable mechanisms for the assembly of the star-forming gas. The
combination of the present-day gas metallicity with the published star
formation history of this galaxy favors a model in which the recent star
forming activity represents the declining tail of the original one.


title:
Kaluza--Klein-type models of de Sitter and Poincar\'e gauge theories of
  gravity

abstract:
  We construct Kaluza--Klein-type models with a de Sitter or Minkowski bundle
in the de Sitter or Poincar\'e gauge theory of gravity, respectively. A
manifestly gauge-invariant formalism has been given. The gravitational dynamics
is constructed by the geometry of the de Sitter or Minkowski bundle and a
global section which plays an important role in the gauge-invariant formalism.
Unlike the old Kaluza--Klein-type models of gauge theory of gravity, a suitable
cosmological term can be obtained in the Lagrangian of our models and the
models in the spin-current-free and torsion-free limit will come back to
general relativity with a corresponding cosmological term. We also generalize
the results to the case with a variable cosmological term.


title:
Unfolding of event-by-event net-charge distributions in heavy-ion
  collisions

abstract:
  An unfolding method, based on Bayes theorem is presented to obtain true
event-by-event net-charge multiplicity distribution from a corresponding
measured distribution, which is subjected to detector artifacts. The unfolding
is demonstrated to work for widely varying particle production mechanism, beam
energy and collision centrality. Further the necessity of taking into account
the detector effects is emphasized before comparing the experimental
measurements to the theoretical calculations, particularly in case of higher
moments. The advantage of this approach being that one need not construct new
observable to cancel out detector effects which loose their ability to be
connected to physical quantities calculable in standard theories.


title:
Random Shortest Paths: Non-Euclidean Instances for Metric Optimization
  Problems

abstract:
  Probabilistic analysis for metric optimization problems has mostly been
conducted on random Euclidean instances, but little is known about metric
instances drawn from distributions other than the Euclidean. This motivates our
study of random metric instances for optimization problems obtained as follows:
Every edge of a complete graph gets a weight drawn independently at random. The
distance between two nodes is then the length of a shortest path (with respect
to the weights drawn) that connects these nodes.
  We prove structural properties of the random shortest path metrics generated
in this way. Our main structural contribution is the construction of a good
clustering. Then we apply these findings to analyze the approximation ratios of
heuristics for matching, the traveling salesman problem (TSP), and the k-median
problem, as well as the running-time of the 2-opt heuristic for the TSP. The
bounds that we obtain are considerably better than the respective worst-case
bounds. This suggests that random shortest path metrics are easy instances,
similar to random Euclidean instances, albeit for completely different
structural reasons.


title:
Backward-angle photoproduction of $\omega$ and $\eta'$ mesons from
  protons at $E_{\gamma}=1.5-3.0$ GeV

abstract:
  We report the measurement of differential cross sections for $\omega$ and
$\eta'$ photoproduction from protons at backward angles
($-1.0<\cos\Theta_{C.M}^{X}<-0.8$) using linearly polarized photons at
$E_{\gamma}=$$1.5-3.0$ GeV. Differential cross sections for $\omega$ mesons are
larger than the predicted $u$-channel contribution in the energy range
$2.0\leq\sqrt{s}\leq2.4$ GeV. The differential cross sections for $\omega$ and
$\eta'$ mesons become closer to the predicted $u$-channel contribution at
$\sqrt{s}>2.4$ GeV. A bump structure in the $\sqrt{s}$ dependence of the
differential cross sections for $\eta'$ mesons was observed at
$\sqrt{s}\sim$2.35 GeV.


title:
A Face-like Structure Detection on Planet and Satellite Surfaces using
  Image Processing

abstract:
  This paper demonstrates that face-like structures are everywhere, and can be
de-tected automatically even with computers. Huge amount of satellite images of
the Earth, the Moon, the Mars are explored and many interesting face-like
structure are detected. Throughout this fact, we believe that science and
technologies can alert people not to easily become an occultist.


title:
Copula-type Estimators for Flexible Multivariate Density Modeling using
  Mixtures

abstract:
  Copulas are popular as models for multivariate dependence because they allow
the marginal densities and the joint dependence to be modeled separately.
However, they usually require that the transformation from uniform marginals to
the marginals of the joint dependence structure is known. This can only be done
for a restricted set of copulas, e.g. a normal copula. Our article introduces
copula-type estimators for flexible multivariate density estimation which also
allow the marginal densities to be modeled separately from the joint
dependence, as in copula modeling, but overcomes the lack of flexibility of
most popular copula estimators. An iterative scheme is proposed for estimating
copula-type estimators and its usefulness is demonstrated through simulation
and real examples. The joint dependence is is modeled by mixture of normals and
mixture of normals factor analyzers models, and mixture of t and mixture of t
factor analyzers models. We develop efficient Variational Bayes algorithms for
fitting these in which model selection is performed automatically. Based on
these mixture models, we construct four classes of copula-type densities which
are far more flexible than current popular copula densities, and outperform
them in simulation and several real data sets.


title:
A study of Nonlinear Galerkin Finite Element for time-dependent
  incompressible Navier-Stokes equation

abstract:
  In this article, we discuss a couple of nonlinear Galerkin methods (NLGM) in
finite element set up for time dependent incompressible Navier-Sotkes
equations. We show the crucial role played by the non-linear term in
determining the rate of convergence of the methods. We have obtained improved
error estimate in $\bL^2$ norm, which is optimal in nature, for linear finite
element approximation, in view of the error estimate available in literature,
in $\bH^1$ norm.


title: Sparsely Sampling the Sky: Regular vs Random Sampling

abstract:
  The next generation of galaxy surveys, aiming to observe millions of
galaxies, are expensive both in time and cost. This raises questions regarding
the optimal investment of this time and money for future surveys. In a previous
work, it was shown that a sparse sampling strategy could be a powerful
substitute for the contiguous observations. However, in this previous paper a
regular sparse sampling was investigated, where the sparse observed patches
were regularly distributed on the sky. The regularity of the mask introduces a
periodic pattern in the window function, which induces periodic correlations at
specific scales. In this paper, we use the Bayesian experimental design to
investigate a random sparse sampling, where the observed patches are randomly
distributed over the total sparsely sampled area. We find that, as there is no
preferred scale in the window function, the induced correlation is evenly
distributed amongst all scales. This could be desirable if we are interested in
specific scales in the galaxy power spectrum, such as the Baryonic Acoustic
Oscillation (BAO) scales. However, for constraining the overall galaxy power
spectrum and the cosmological parameters, there is no preference over regular
or random sampling. Hence any approach that is practically more suitable can be
chosen and we can relax the regular-grid condition for the distribution of the
observed patches.


title: The Ripple Pond: Enabling Spiking Networks to See

abstract:
  In this paper we present the biologically inspired Ripple Pond Network (RPN),
a simply connected spiking neural network that, operating together with
recently proposed PolyChronous Networks (PCN), enables rapid, unsupervised,
scale and rotation invariant object recognition using efficient spatio-temporal
spike coding. The RPN has been developed as a hardware solution linking
previously implemented neuromorphic vision and memory structures capable of
delivering end-to-end high-speed, low-power and low-resolution recognition for
mobile and autonomous applications where slow, highly sophisticated and power
hungry signal processing solutions are ineffective. Key aspects in the proposed
approach include utilising the spatial properties of physically embedded neural
networks and propagating waves of activity therein for information processing,
using dimensional collapse of imagery information into amenable temporal
patterns and the use of asynchronous frames for information binding.


title:
Validation of GEANT4 Monte Carlo Models with a Highly Granular
  Scintillator-Steel Hadron Calorimeter

abstract:
  Calorimeters with a high granularity are a fundamental requirement of the
Particle Flow paradigm. This paper focuses on the prototype of a hadron
calorimeter with analog readout, consisting of thirty-eight scintillator layers
alternating with steel absorber planes. The scintillator plates are finely
segmented into tiles individually read out via Silicon Photomultipliers. The
presented results are based on data collected with pion beams in the energy
range from 8GeV to 100GeV. The fine segmentation of the sensitive layers and
the high sampling frequency allow for an excellent reconstruction of the
spatial development of hadronic showers. A comparison between data and Monte
Carlo simulations is presented, concerning both the longitudinal and lateral
development of hadronic showers and the global response of the calorimeter. The
performance of several GEANT4 physics lists with respect to these observables
is evaluated.


title:
The effect of Dirac phase on acoustic vortex in media with screw
  dislocation

abstract:
  We study acoustic vortex in media with screw dislocation using the
Katanaev-Volovich theory of defects. It is shown that the screw dislocation
affects the beam's orbital angular momentum and changes the acoustic vortex
strength. This change is a manifestation of topological Dirac phase and is
robust against fluctuations in the system.


title: Another Conversation with Persi Diaconis

abstract:
  Persi Diaconis was born in New York on January 31, 1945. Upon receiving a
Ph.D. from Harvard in 1974 he was appointed Assistant Professor at Stanford.
Following periods as Professor at Harvard (1987-1997) and Cornell (1996-1998),
he has been Professor in the Departments of Mathematics and Statistics at
Stanford since 1998. He is a member of the National Academy of Sciences, a past
President of the IMS and has received honorary doctorates from Chicago and four
other universities. The following conversation took place at his office and at
Aldous's home in early 2012.


title: Elements of noncommutative geometry in inverse problems on manifolds

abstract:
  We deal with two dynamical systems associated with a Riemannian manifold with
boundary. The first one is a system governed by the scalar wave equation, the
second is governed by the Maxwell equations. Both of the systems are controlled
from the boundary. The inverse problem is to recover the manifold via the
relevant measurements at the boundary (inverse data).
  We show that the inverse data determine a C*-algebras, whose (topologized)
spectra are identical to the manifold. By this, to recover the manifold is to
determine a proper algebra from the inverse data, find its spectrum, and
provide the spectrum with a Riemannian structure.
  The paper develops an algebraic version of the boundary control method, which
is an approach to inverse problems based on their relations to control theory.


title:
Strangeness magnetic form factor of the proton in the extended chiral
  quark model

abstract:
  Background: Unravelling the role played by nonvalence flavors in baryons is
crucial in deepening our comprehension of QCD. Strange quark, a component of
the higher Fock states in baryons, is an appropriate tool to investigate
nonperturbative mechanisms generated by the pure sea quark.
  Purpose: Study the magnitude and the sign of the strangeness magnetic moment
$\mu_s$ and the magnetic form factor ($G_M^s$) of the proton.
  Methods: Within an extended chiral constituent quark model, we investigate
contributions from all possible five-quark components to $\mu_s$ and $G_M^s
(Q^2)$ in the four-vector momentum range $Q^2 \leq 1$ (GeV/c)$^2$. Probability
of the strangeness component in the proton wave function is calculated
employing the $^3 P_0$ model.
  Results: Predictions are obtained without any adjustable parameters.
Observables $\mu_s$ and $G_M^s (Q^2)$ are found to be small and negative,
consistent with the lattice-QCD findings as well as with the latest data
released by the PVA4 and HAPPEX Collaborations.
  Conclusions: Due to sizeable cancelations among different configurations
contributing to the strangeness magnetic moment of the proton, it is
indispensable to (i) take into account all relevant five-quark components and
include both diagonal and non-diagonal terms, (ii) handle with care the
oscillator harmonic parameter $\omega_5$ and the ${s \bar s}$ component
probability.


title: Scanning Tunneling Microscopy in the superconductor LaSb2

abstract:
  We present very low temperature (0.15 K) scanning tunneling microscopy and
spectroscopy experiments in the layered superconductor LaSb$_2$. We obtain
topographic microscopy images with surfaces showing hexagonal and square atomic
size patterns, and observe in the tunneling conductance a superconducting gap.
We find well defined quasiparticle peaks located at a bias voltage comparable
to the weak coupling s-wave BCS expected gap value (0.17 meV). The amount of
states at the Fermi level is however large and the curves are significantly
broadened. We find T$_c$ of 1.2 K by following the tunneling conductance with
temperature.


title:
Relativistic effects and dark matter in the Solar system from
  observations of planets and spacecraft

abstract:
  The high precision of the latest version of the planetary ephemeris EPM2011
enables one to explore more accurately a variety of small effects in the solar
system. The processing of about 678 thousand of position observations of
planets and spacecrafts for 1913--2011 with the predominance of modern radar
measurements resulted in improving the PPN parameters, dynamic oblateness of
the Sun, secular variation of the heliocentric gravitational constant
$GM_{\odot}$, and variation range of the gravitational constant $G$. This
processing made it possible to estimate the potential additional gravitational
influence of dark matter on the motion of the solar system bodies. The density
of dark matter ${\rho}_{dm}$, if any, turned out to be substantially below the
accuracy achieved by the present determination of such parameters. At the
distance of the orbit of Saturn the density ${\rho}_{dm}$ is estimated to be
under $1.1\cdot10^{-20}$ g/cm$^3$, and the mass of dark matter in the area
inside the orbit of Saturn is less than $7.9\cdot10^{-11}$ M$_{\odot}$ even
taking into account its possible tendency to concentrate in the center.


title: Fredholm properties of nonlocal differential operators via spectral flow

abstract:
  We establish Fredholm properties for a class of nonlocal differential
operators. Using mild convergence and localization conditions on the nonlocal
terms, we also show how to compute Fredholm indices via a generalized spectral
flow, using crossing numbers of generalized spatial eigenvalues. We illustrate
possible applications of the results in a nonlinear and a linear setting. We
first prove the existence of small viscous shock waves in nonlocal conservation
laws with small spatially localized source terms. We also show how our results
can be used to study edge bifurcations in eigenvalue problems using
Lyapunov-Schmidt reduction instead of a Gap Lemma.


title: On stable conjugacy of finite subgroups of the plane Cremona group, I

abstract:
  We discuss the problem of stable conjugacy of finite subgroups of Cremona
groups. We show that the group $H^1(G,Pic(X))$ is a stable birational invariant
and compute this group in some cases.


title: Splitting of operads and Rota-Baxter operators on operads

abstract:
  This paper establishes a uniform procedure to split the operations in any
algebraic operad, generalizing previous known notions of splitting algebraic
structures from the dendriform algebra of Loday that splits the associative
operation to the successors that split any binary operad. Examples are provided
for various $n$-associative algebras, $n$-Lie algebras, $A_\infty$ algebras and
$L_\infty$ algebras. Further, the concept of a Rota-Baxter operator, first
showing its importance in the associative and Lie algebra context and then
generalized to any binary operads, is generalized to arbitrary operads. The
classical links from the Rota-Baxter associative algebra to the dendriform
algebra and its numerous generalizations are further generalized and unified as
the link from the Rota-Baxter operator on an operad to the splitting of the
operad. Finally, the remarkable fact that any dendriform algebra can be
recovered from a relative Rota-Baxter operator is generalized to the context of
operads with the generalized notion of a relative Rota-Baxter operator for any
operad.


title:
Holomorphic line bundles over domains in Cousin groups and the algebraic
  dimension of OT-manifolds

abstract:
  In this paper we extend results due to Vogt on line bundles over Cousin
groups to the case of domains stable by the maximal compact subgroup. This is
used in the sequel to show that the algebraic dimension of OT-manifolds is
zero. In the last part we establish that certain Cousin groups, in particular
those arising from the construction of OT-manifolds, have finite-dimensional
irregularity.


title: Past of a quantum particle and weak measurement

abstract:
  We present an analysis of a double Mach-Zehnder interferometer in which an
ensemble of identical pre- and postselected particles leave a weak trace. A
knowledge of the weak value partially destroys the quantum interference. The
results, contrary to some recent claims, are in accordance with the usual
quantum mechanical expectations.


title: On graded Gorenstein injective dimension

abstract:
  There are nice relations between graded homological dimensions and ordinary
homological dimensions. We study the Gorenstein injective dimension of a
complex of graded modules denoted by $^*\Gid$, and derive its properties. In
particular we prove the Chouinard's like formula for $^*\Gid$, and compare it
with the usual Gorenstein injective dimension.


title: Modal Interface Automata

abstract:
  De Alfaro and Henzinger's Interface Automata (IA) and Nyman et al.'s recent
combination IOMTS of IA and Larsen's Modal Transition Systems (MTS) are
established frameworks for specifying interfaces of system components. However,
neither IA nor IOMTS consider conjunction that is needed in practice when a
component shall satisfy multiple interfaces, while Larsen's MTS-conjunction is
not closed and Bene\v{s} et al.'s conjunction on disjunctive MTS does not treat
internal transitions. In addition, IOMTS-parallel composition exhibits a
compositionality defect. This article defines conjunction (and also
disjunction) on IA and disjunctive MTS and proves the operators to be
'correct', i.e., the greatest lower bounds (least upper bounds) wrt. IA- and
resp. MTS-refinement. As its main contribution, a novel interface theory called
Modal Interface Automata (MIA) is introduced: MIA is a rich subset of IOMTS
featuring explicit output-must-transitions while input-transitions are always
allowed implicitly, is equipped with compositional parallel, conjunction and
disjunction operators, and allows a simpler embedding of IA than Nyman's. Thus,
it fixes the shortcomings of related work, without restricting designers to
deterministic interfaces as Raclet et al.'s modal interface theory does.


title:
A convenient implementation of the overlap between arbitrary
  Hartree-Fock-Bogoliubov vacua for projection

abstract:
  Overlap between Hartree-Fock-Bogoliubov(HFB) vacua is very important in the
beyond mean-field calculations. However, in the HFB transformation, the $U,V$
matrices are sometimes singular due to the exact emptiness ($v_i=0$) or full
occupation ($u_i=0$) of some single-particle orbits. This singularity may cause
some problem in evaluating the overlap between HFB vacua through Pfaffian. We
found that this problem can be well avoided by setting those zero occupation
numbers to some tiny values (e.g., $u_i,v_i=10^{-8}$). This treatment does not
change the HFB vacuum state because $u_i^2,v_i^2=10^{-16}$ are numerically zero
relative to 1. Therefore, for arbitrary HFB transformation, we say that the
$U,V$ matrices can always be nonsingular. From this standpoint, we present a
new convenient Pfaffian formula for the overlap between arbitrary HFB vacua,
which is especially suitable for symmetry restoration. Testing calculations
have been performed for this new formula. It turns out that our method is
reliable and accurate in evaluating the overlap between arbitrary HFB vacua.


title: Real-space density profile reconstruction of stacked voids

abstract:
  We present a non-parametric, model-independent method to reconstruct the
spherical density profiles of void stacks in real space, without redshift-space
distortions. Our method uses the expected spherical symmetry of stacked voids
to build the shape of the spherical density profile of cosmic voids in real
space without any assumption about the cosmological model. We test the
reconstruction algorithm with both a toy model and a full dark matter
simulation. We present the result for the simulation: the reconstruction of the
spherical density profile for a simulated stacked void in real space. We also
present a first application of the algorithm to reconstruct real cosmic void
stacks density profiles in real space from the Sloan Digital Sky Survey (Sutter
et al. 2012b). We discuss capabilities of the algorithm and possible future
improvements. Reconstructed density profiles from real voids open the way to
the study of the spherically averaged dynamical structure of voids.


title:
Diffusion limit of kinetic equations for multiple species charged
  particles

abstract:
  In ionic solutions, there are multi-species charged particles (ions) with
different properties like mass, charge etc. Macroscopic continuum models like
the Poisson-Nernst-Planck (PNP) systems have been extensively used to describe
the transport and distribution of ionic species in the solvent. Starting from
the kinetic theory for the ion transport, we study a
Vlasov-Poisson-Fokker-Planck (VPFP) system in a bounded domain with reflection
boundary conditions for charge distributions and prove that the global
renormalized solutions of the VPFP system converge to the global weak solutions
of the PNP system, as the small parameter related to the scaled thermal
velocity and mean free path tends to zero. Our results may justify the PNP
system as a macroscopic model for the transport of multi-species ions in dilute
solutions.


title: The effect of baroque music on the PassPoints graphical password

abstract:
  Graphical passwords have been demonstrated to be the possible alternatives to
traditional alphanumeric passwords. However, they still tend to follow
predictable patterns that are easier to attack. The crux of the problem is
users' memory limitations. Users are the weakest link in password
authentication mechanism. It shows that baroque music has positive effects on
human memorizing and learning. We introduce baroque music to the PassPoints
graphical password scheme and conduct a laboratory study in this paper. Results
shown that there is no statistic difference between the music group and the
control group without music in short-term recall experiments, both had high
recall success rates. But in long-term recall, the music group performed
significantly better. We also found that the music group tended to set
significantly more complicated passwords, which are usually more resistant to
dictionary and other guess attacks. But compared with the control group, the
music group took more time to log in both in short-term and long-term tests.
Besides, it appears that background music does not work in terms of hotspots.


title:
Can background baroque music help to improve the memorability of
  graphical passwords?

abstract:
  Graphical passwords have been proposed as an alternative to alphanumeric
passwords with their advantages in usability and security. However, they still
tend to follow predictable patterns that are easier for attackers to exploit,
probably due to users' memory limitations. Various literatures show that
baroque music has positive effects on human learning and memorizing. To
alleviate users' memory burden, we investigate the novel idea of introducing
baroque music to graphical password schemes (specifically DAS, PassPoints and
Story) and conduct a laboratory study to see whether it is helpful. In a ten
minutes short-term recall, we found that participants in all conditions had
high recall success rates that were not statistically different from each
other. After one week, the music group coped PassPoints passwords significantly
better than the group without music. But there was no statistical difference
between two groups in recalling DAS passwords or Story passwords. Further more,
we found that the music group tended to set significantly more complicated
PassPoints passwords but less complicated DAS passwords.


title: On the quantifier-free dynamic complexity of Reachability

abstract:
  The dynamic complexity of the reachability query is studied in the dynamic
complexity framework of Patnaik and Immerman, restricted to quantifier-free
update formulas.
  It is shown that, with this restriction, the reachability query cannot be
dynamically maintained, neither with binary auxiliary relations nor with unary
auxiliary functions, and that ternary auxiliary relations are more powerful
with respect to graph queries than binary auxiliary relations.
  Further inexpressibility results are given for the reachability query in a
different setting as well as for a syntactical restriction of quantifier-free
update formulas. Moreover inexpressibility results for some other queries are
presented.


title:
Global convergence of diluted iterations in maximum-likelihood quantum
  tomography

abstract:
  In this paper we present an inexact stepsize selection for the Diluted R\rho
R algorithm, used to obtain the maximum likelihood estimate to the density
matrix in quantum state tomography. We give a new interpretation for the
diluted R\rho R iterations that allows us to prove the global convergence under
weaker assumptions. Thus, we propose a new algorithm which is globally
convergent and suitable for practical implementation.


title: Physeter catodon localization by sparse coding

abstract:
  This paper presents a spermwhale' localization architecture using jointly a
bag-of-features (BoF) approach and machine learning framework. BoF methods are
known, especially in computer vision, to produce from a collection of local
features a global representation invariant to principal signal transformations.
Our idea is to regress supervisely from these local features two rough
estimates of the distance and azimuth thanks to some datasets where both
acoustic events and ground-truth position are now available. Furthermore, these
estimates can feed a particle filter system in order to obtain a precise
spermwhale' position even in mono-hydrophone configuration. Anti-collision
system and whale watching are considered applications of this work.


title:
Propositional Dynamic Logic with Converse and Repeat for Message-Passing
  Systems

abstract:
  The model checking problem for propositional dynamic logic (PDL) over message
sequence charts (MSCs) and communicating finite state machines (CFMs) asks,
given a channel bound $B$, a PDL formula $\varphi$ and a CFM $\mathcal{C}$,
whether every existentially $B$-bounded MSC $M$ accepted by $\mathcal{C}$
satisfies $\varphi$. Recently, it was shown that this problem is
PSPACE-complete.
  In the present work, we consider CRPDL over MSCs which is PDL equipped with
the operators converse and repeat. The former enables one to walk back and
forth within an MSC using a single path expression whereas the latter allows to
express that a path expression can be repeated infinitely often. To solve the
model checking problem for this logic, we define message sequence chart
automata (MSCAs) which are multi-way alternating parity automata walking on
MSCs. By exploiting a new concept called concatenation states, we are able to
inductively construct, for every CRPDL formula $\varphi$, an MSCA precisely
accepting the set of models of $\varphi$. As a result, we obtain that the model
checking problem for CRPDL and CFMs is still in PSPACE.


title:
A spectroscopic and proper motion search of Sloan digital Sky Survey:
  red subdwarfs in binary systems

abstract:
  Red subdwarfs in binary systems are crucial for both model calibration and
spectral classification. We search for red subdwarfs in binary systems from a
sample of high proper motion objects with Sloan digital Sky Survey
spectroscopy. We present here discoveries from this search, as well as
highlight several additional objects of interest. We find 30 red subdwarfs in
wide binary systems including: two with spectral type of esdM5.5, 6 companions
to white dwarfs and 3 carbon enhanced red subdwarfs with normal red subdwarf
companions. 15 red subdwarfs in our sample are partially resolved close binary
systems. With this binary sample, we estimate the low limit of the red subdwarf
binary fraction of ~ 10%. We find that the binary fraction goes down with
decreasing masses and metallicities of red subdwarfs. A spectroscopic esdK7
subdwarf + white dwarf binary candidate is also reported. 30 new M subdwarfs
have spectral type of >= M6 in our sample. We also derive relationships between
spectral types and absolute magnitudes in the optical and near-infrared for M
and L subdwarfs, and we present an M subdwarf sample with measured U, V, W
space velocities.


title: Searching for collective behavior in a network of real neurons

abstract:
  Maximum entropy models are the least structured probability distributions
that exactly reproduce a chosen set of statistics measured in an interacting
network. Here we use this principle to construct probabilistic models which
describe the correlated spiking activity of populations of up to 120 neurons in
the salamander retina as it responds to natural movies. Already in groups as
small as 10 neurons, interactions between spikes can no longer be regarded as
small perturbations in an otherwise independent system; for 40 or more neurons
pairwise interactions need to be supplemented by a global interaction that
controls the distribution of synchrony in the population. Here we show that
such "K-pairwise" models--being systematic extensions of the previously used
pairwise Ising models--provide an excellent account of the data. We explore the
properties of the neural vocabulary by: 1) estimating its entropy, which
constrains the population's capacity to represent visual information; 2)
classifying activity patterns into a small set of metastable collective modes;
3) showing that the neural codeword ensembles are extremely inhomogenous; 4)
demonstrating that the state of individual neurons is highly predictable from
the rest of the population, allowing the capacity for error correction.


title:
An implementation of CAD in Maple utilising problem formulation,
  equational constraints and truth-table invariance

abstract:
  Cylindrical algebraic decomposition (CAD) is an important tool for the
investigation of semi-algebraic sets, with applications within algebraic
geometry and beyond. We recently reported on a new implementation of CAD in
Maple which implemented the original algorithm of Collins and the subsequent
improvement to projection by McCallum. Our implementation was in contrast to
Maple's in-built CAD command, based on a quite separate theory. Although
initially developed as an investigative tool to compare the algorithms, we
found and reported that our code offered functionality not currently available
in any other existing implementations. One particularly important piece of
functionality is the ability to produce order-invariant CADs. This has allowed
us to extend the implementation to produce CADs invariant with respect to
either equational constraints (ECCADs) or the truth-tables of sequences of
formulae (TTICADs). This new functionality is contained in the second release
of our code, along with commands to consider problem formulation which can be a
major factor in the tractability of a CAD. In the report we describe the new
functionality and some theoretical discoveries it prompted. We describe how the
CADs produced using equational constraints are able to take advantage of not
just improved projection but also improvements in the lifting phase. We also
present an extension to the original TTICAD algorithm which increases both the
applicability of TTICAD and its relative benefit over other algorithms. The
code and an introductory Maple worksheet / pdf demonstrating the full
functionality of the package are freely available online.


title:
Humoral immunocompetence in relation to condition, size, asymmetry and
  MHC class II variation in great snipe (Gallinago media) males

abstract:
  1. In recent years many studies have investigated the relationships between
different aspects of the immune system and ecology in various organisms. Yet,
it remains unclear why individuals differ in their ability to mount an immune
response against various antigens (often referred to as 'immunocompetence').
Different kinds of trade-offs may be involved and costs of mounting the immune
response often lead to condition dependent effects. 2. We investigated how
variation in condition, morphology and genetic variables influenced the amount
of antibodies produced against two novel antigens in a migrating bird, the
great snipe (Gallinago media). 3. We found no evidence for condition dependence
of the antibody response and no effect of MHC genetics. There was, however, a
weak negative correlation between body size and the amount of antibody
production, which may indicate a trade-off between growth and immune response
in this species.


title:
Development of the Liquid Level Meters for the PandaX Dark Matter
  Detector

abstract:
  The two-phase xenon detector is at the frontier of dark matter direct search.
This kind of detector uses liquid xenon as the sensitive target and is operated
in two-phase (liquid/gas) mode, where the liquid level needs to be monitored
and controlled in sub-millimeter precision. In this paper, we present a
detailed design and study of two kinds of level meters for the PandaX dark
matter detector. The long level meter is used to monitor the overall liquid
level while short level meters are used to monitor the inclination of the
detector. These level meters are cylindrical capacitors custom-made from two
concentric metal tubes. Their capacitance values are read out by a universal
transducer interface chip and recorded by the PandaX slow control system. We
present the developments that lead to level meters with long-term stability and
sub-millimeter precision. Fluctuations (standard deviations) of less than 0.02
mm for the short level meters and less than 0.2 mm for the long level meter
were achieved during a few days of test operation.


title: Direct Imaging of Dynamic Glassy Behavior in a Strained Manganite Film

abstract:
  Complex many-body interaction in perovskite manganites gives rise to a strong
competition between ferromagnetic metallic and charge ordered phases with
nanoscale electronic inhomogeneity and glassy behaviors. Investigating this
glassy state requires high resolution imaging techniques with sufficient
sensitivity and stability. Here, we present the results of a near-field
microwave microscope imaging on the strain driven glassy state in a manganite
film. The high contrast between the two electrically distinct phases allows
direct visualization of the phase separation. The low temperature microscopic
configurations differ upon cooling with different thermal histories. At
sufficiently high temperatures, we observe switching between the two phases in
either direction. The dynamic switching, however, stops below the glass
transition temperature. Compared with the magnetization data, the phase
separation was microscopically frozen, while spin relaxation was found in a
short period of time.


title: Unavoidable vertex-minors in large prime graphs

abstract:
  A graph is prime (with respect to the split decomposition) if its vertex set
does not admit a partition (A,B) (called a split) with |A|, |B| >= 2 such that
the set of edges joining A and B induces a complete bipartite graph.
  We prove that for each n, there exists N such that every prime graph on at
least N vertices contains a vertex-minor isomorphic to either a cycle of length
n or a graph consisting of two disjoint cliques of size n joined by a matching.


title:
Pattern recognition of $^{136}$Xe double beta decay events and
  background discrimination in a high pressure Xenon TPC

abstract:
  High pressure gas detectors offer advantages for the detection of rare
events, where background reduction is crucial. For the neutrinoless double beta
decay of 136Xe a high pressure xenon gas Time Projection Chamber (TPC) combines
a good energy resolution and a detailed topological information of each event.
The ionization topology of the double beta decay event of 136Xe in gaseous
xenon has a characteristic shape defined by the two straggling electron tracks
ending up in two higher ionization charge density blobs. With a properly
pixelized readout, this topological information is invaluable to perform
powerful background discrimination. In this study we carry out detailed
simulations of the signal topology, as well as the competing topologies from
gamma events that typically compose the background at these energies. We define
observables based on graph theory concepts and develop automated discrimination
algorithms which reduce the background level in around three orders of
magnitude while keeping signal efficiency of 40%. This result supports the
competitiveness of current or future double beta experiments based on gas TPCs,
like the Neutrino Xenon TPC (NEXT) currently under construction in the
Laboratorio Subterraneo de Canfranc (LSC).


title: Baryon number of the Universe as a result of extra space dynamics

abstract:
  Origin of baryon asymmetry is studied in the framework of extra dimensional
approach. Baryon excess production and the symmetrization of extra-space are
performed simultaneously. Baryon number is conserved long after the
inflationary stage when the U(1) symmetry is achieved.


title:
Prospects for measuring the 229Th isomer energy using a metallic
  magnetic microcalorimeter

abstract:
  The Thorium-229 isotope features a nuclear isomer state with an extremely low
energy. The currently most accepted energy value, 7.8 +- 0.5 eV, was obtained
from an indirect measurement using a NASA x-ray microcalorimeter with an
instrumental resolution 26 eV. We study, how state-of-the-art magnetic metallic
microcalorimeters with an energy resolution down to a few eV can be used to
measure the isomer energy. In particular, resolving the 29.18 keV doublet in
the \gamma-spectrum following the \alpha-decay of Uranium-233, corresponding to
the decay into the ground and isomer state, allows to measure the isomer
transition energy without additional theoretical input parameters, and increase
the energy accuracy. We study the possibility of resolving the 29.18 keV line
as a doublet and the dependence of the attainable precision of the energy
measurement on the signal and background count rates and the instrumental
resolution.


title:
From the microscopic to the van Hove regime in the XY chain out of
  equilibrium

abstract:
  Using the framework of rigorous algebraic quantum statistical mechanics, we
construct the unique nonequilibrium steady state in the isotropic XY chain in
which a sample of arbitrary finite size is coupled by a bond coupling
perturbation of arbitrary strength to two infinitely extended thermal
reservoirs, and we prove that this state is thermodynamically nontrivial.
Moreover, extracting the leading second order contribution to its microscopic
entropy production and deriving its entropy production in the van Hove weak
coupling regime, we prove that, in the mathematically and physically important
XY chain, the van Hove regime reproduces the leading order contribution to the
microscopic regime.