title: Spin-Flipping in Pt and at Co/Pt Interfaces

abstract:
  There has been recent controversy about the magnitude of spin-flipping in the
heavy metal Pt, characterized by the spin-diffusion length, lsf(Pt) We propose
a resolution of this controversy, and also present evidence for the importance
of a phenomenon neglected in prior studies of transport across sputtered
Ferromagnetic/Pt (F/Pt) interfaces, spin-flipping at the interface. The latter
is characterized by an interface spin-flipping parameter, delta(Co/Pt) that
specifies the probability P = [1 - exp(-delta)] of a conduction electron
flipping its spin direction as it traverses a Co/Pt interface. From studies of
the Current-Perpendicular-to-Plane (CPP) Resistances and Magnetoresistances of
sputtered ferromagnetically coupled Co/Pt multilayers by themselves, and
embedded within Py-based Double Exchange-biased Spin-Valves, we derive values
at 4.2K of delta(Co/Pt) = 0.9 (+0.5/-0.2), the interface specific resistance,
AR*(Co/Pt) = 0.74 +/- 0.15 fohm-m(2). and the interface spin-scattering
asymmetry, gamma(Co/Pt) = 0.58 +/- 0.12. This value of delta(Co/Pt) is much
larger than ones previously found for interfaces involving Co but not Pt. To
derive delta requires knowledge of the spin-diffusion length, lsf(Pt), for our
sputtered Pt. We derive lsf(Pt) from separate measurements. Combining our
results with those from others, we find that lsf(Pt) for Pt is approximately
proportional to the inverse resistivity, 1/rho(Pt).


title:
A Kamenev-type oscillation result for a linear $(1+\alpha)$--order
  fractional differential equation

abstract:
  We investigate the eventual sign changing for the solutions of the linear
equation $\left(x^{(\alpha)}\right)^{\prime}+q(t)x=0$, $t\geq0$, when the
functional coefficient $q$ satisfies the Kamenev-type restriction
$\limsup\limits_{t\rightarrow+\infty}\frac{1}{t^{\varepsilon}}\int_{t_0}^{t}(t-s)^{\varepsilon}q(s)ds=+\infty$
for some $\varepsilon>2$, $t_{0}>0$. The operator $x^{(\alpha)}$ is the Caputo
differential operator and $\alpha\in(0,1)$.


title: An FCA-based Boolean Matrix Factorisation for Collaborative Filtering

abstract:
  We propose a new approach for Collaborative Filtering which is based on
Boolean Matrix Factorisation (BMF) and Formal Concept Analysis. In a series of
experiments on real data (Movielens dataset) we compare the approach with the
SVD- and NMF-based algorithms in terms of Mean Average Error (MAE). One of the
experimental consequences is that it is enough to have a binary-scaled rating
data to obtain almost the same quality in terms of MAE by BMF than for the
SVD-based algorithm in case of non-scaled data.


title: Context unification is in PSPACE

abstract:
  Contexts are terms with one `hole', i.e. a place in which we can substitute
an argument. In context unification we are given an equation over terms with
variables representing contexts and ask about the satisfiability of this
equation. Context unification is a natural subvariant of second-order
unification, which is undecidable, and a generalization of word equations,
which are decidable, at the same time. It is the unique problem between those
two whose decidability is uncertain (for already almost two decades). In this
paper we show that the context unification is in PSPACE. The result holds under
a (usual) assumption that the first-order signature is finite.
  This result is obtained by an extension of the recompression technique,
recently developed by the author and used in particular to obtain a new PSPACE
algorithm for satisfiability of word equations, to context unification. The
recompression is based on performing simple compression rules (replacing pairs
of neighbouring function symbols), which are (conceptually) applied on the
solution of the context equation and modifying the equation in a way so that
such compression steps can be in fact performed directly on the equation,
without the knowledge of the actual solution.


title: Sharpening Geometric Inequalities using Computable Symmetry Measures

abstract:
  Many classical geometric inequalities on functionals of convex bodies depend
on the dimension of the ambient space. We show that this dimension dependence
may often be replaced (totally or partially) by different symmetry measures of
the convex body. Since these coefficients are bounded by the dimension but
possibly smaller, our inequalities sharpen the original ones. Since they can
often be computed efficiently, the improved bounds may also be used to obtain
better bounds in approximation algorithms.


title: NLO QCD corrections to WZjj production at the LHC

abstract:
  We present a summary of the first calculation of NLO QCD corrections to WZjj
production with leptonic decays at the LHC. Our results show that the
next-to-leading order corrections reduce significantly the scale uncertainties.


title: Spectral_Engineering_with_CMOS_compatible_SOI_Photonic_Molecules

abstract:
  Photonic systems based on microring resonators have a fundamental constrain
given by the strict relationship among free spectral range (FSR), total quality
factor (QT) and resonator size, intrinsically making filter spacing, photonic
lifetime and footprint interdependent. Here we break this paradigm employing
CMOS compatible Silicon-on-Insulator (SOI) photonic molecules based on coupled
multiple ring resonators. The resonance wavelengths and their respective
linewidths are controlled by the hybridization of the quasi-orthogonal photonic
states. We demonstrate photonic molecules with doublet and triplet resonances
with spectral spliting only achievable with single rings orders of magnitude
larger in foot print. Besides, these splitting are potentially controllable
based on the coupling (bonds) between resonators. Finally, the spatial
distribution of the hybrid states allows up to sevenfold QT enhancement.


title:
Phase Transition and Regularized Bootstrap in Large Scale $t$-tests with
  False Discovery Rate Control

abstract:
  Applying Benjamini and Hochberg (B-H) method to multiple Student's $t$ tests
is a popular technique in gene selection in microarray data analysis. Because
of the non-normality of the population, the true p-values of the hypothesis
tests are typically unknown. Hence, it is common to use the standard normal
distribution N(0,1), Student's $t$ distribution $t_{n-1}$ or the bootstrap
method to estimate the p-values. In this paper, we first study N(0,1) and
$t_{n-1}$ calibrations. We prove that, when the population has the finite 4-th
moment and the dimension $m$ and the sample size $n$ satisfy $\log
m=o(n^{1/3})$, B-H method controls the false discovery rate (FDR) at a given
level $\alpha$ asymptotically with p-values estimated from N(0,1) or $t_{n-1}$
distribution. However, a phase transition phenomenon occurs when $\log m\geq
c_{0}n^{1/3}$. In this case, the FDR of B-H method may be larger than $\alpha$
or even tends to one. In contrast, the bootstrap calibration is accurate for
$\log m=o(n^{1/2})$ as long as the underlying distribution has the sub-Gaussian
tails. However, such light tailed condition can not be weakened in general. The
simulation study shows that for the heavy tailed distributions, the bootstrap
calibration is very conservative. In order to solve this problem, a regularized
bootstrap correction is proposed and is shown to be robust to the tails of the
distributions. The simulation study shows that the regularized bootstrap method
performs better than the usual bootstrap method.


title: Recursively-Regular Subdivisions and Applications

abstract:
  We generalize regular subdivisions (polyhedral complexes resulting from the
projection of the lower faces of a polyhedron) introducing the class of
recursively-regular subdivisions. Informally speaking, a recursively-regular
subdivision is a subdivision that can be obtained by splitting some faces of a
regular subdivision by other regular subdivisions (and continue recursively).
We also define the \emph{finest regular coarsening} and the \emph{regularity
tree} of a polyhedral complex. We prove that recursively-regular subdivisions
are not necessarily connected by flips and that they are acyclic with respect
to the in-front relation. We show that the finest regular coarsening of a
subdivision can be efficiently computed, and that whether a subdivision is
recursively regular can be efficiently decided. As an application, we also
extend a theorem known since 1981 on illuminating space by cones and present
connections of recursive regularity to tensegrity theory and graph-embedding
problems.


title: Selected strong decay modes of Y(4260)

abstract:
  In present work the Y(4260) resonance is considered as a weakly bound state
of a pseudoscalar D and an axial D1 charm meson. We consider the two-body decay
Y(4260) -> Zc(3900) + pi where Zc(3900) is treated as hadron molecule as well.
Moreover we compute the Y(4260) decay modes J/psi pi(+) pi(-), recently
observed by the BESIII Collaboration, and psi(2S) pi(+) pi(-). In the last
process both the contact diagram with D D1 -> psi(nS) pi(+) pi(-) and the
resonance diagram with D D1 -> Zc(3900) + pi -> psi(nS) pi(+) pi(-) are taken
into account.


title: A method to compute periodic sums

abstract:
  In a number of problems in computational physics, a finite sum of kernel
functions centered at $N$ particle locations located in a box in three
dimensions must be extended by imposing periodic boundary conditions on box
boundaries. Even though the finite sum can be efficiently computed via fast
summation algorithms, such as the fast multipole method (FMM), the periodized
extension is usually treated via a different algorithm, Ewald summation,
accelerated via the fast Fourier transform (FFT). A different approach to
compute this periodized sum just using a blackbox finite fast summation
algorithm is presented in this paper. The method splits the periodized sum in
to two parts. The first, comprising the contribution of all points outside a
large sphere enclosing the box, and some of its neighbors, is approximated
inside the box by a collection of kernel functions ("sources") placed on the
surface of the sphere or using an expansion in terms of spectrally convergent
local basis functions. The second part, comprising the part inside the sphere,
and including the box and its immediate neighborhood, is treated via available
summation algorithms. The coefficients of the sources are determined by least
squares collocation of the periodicity condition of the total potential,
imposed on a circumspherical surface for the box. While the method is presented
in general, details are worked out for the case of evaluating electrostatic
potentials and forces. Results show that when used with the FMM, the periodized
sum can be computed to any specified accuracy, at an additional cost of the
order of the free-space FMM. Several technical details and efficient algorithms
for auxiliary computations are provided, as are numerical comparisons.


title: Fast Computation of Wasserstein Barycenters

abstract:
  We present new algorithms to compute the mean of a set of empirical
probability measures under the optimal transport metric. This mean, known as
the Wasserstein barycenter, is the measure that minimizes the sum of its
Wasserstein distances to each element in that set. We propose two original
algorithms to compute Wasserstein barycenters that build upon the subgradient
method. A direct implementation of these algorithms is, however, too costly
because it would require the repeated resolution of large primal and dual
optimal transport problems to compute subgradients. Extending the work of
Cuturi (2013), we propose to smooth the Wasserstein distance used in the
definition of Wasserstein barycenters with an entropic regularizer and recover
in doing so a strictly convex objective whose gradients can be computed for a
considerably cheaper computational cost using matrix scaling algorithms. We use
these algorithms to visualize a large family of images and to solve a
constrained clustering problem.


title: Quantum Dot Spin Cellular Automata for Realizing a Quantum Processor

abstract:
  We show how "single" quantum dots, each hosting a singlet-triplet qubit, can
be placed in arrays to build a spin quantum cellular automaton. A fast ($\sim
10$ ns) deterministic coherent singlet-triplet filtering, as opposed to current
incoherent tunneling/slow-adiabatic based quantum gates (operation time $\sim
300$ ns), can be employed to produce a two-qubit gate through capacitive
(electrostatic) coupling that can operate over significant distances. This is
the coherent version of the widely discussed charge and nano-magnet cellular
automata and would offer speed, reduce dissipation, perform quantum
computation, while interfacing smoothly with its classical counterpart. This
combines the best of two worlds -- the coherence of spin pairs known from
quantum technologies, and the strength and range of electrostatic couplings
from the charge based classical cellular automata.


title:
Hierarchical Block Structures and High-resolution Model Selection in
  Large Networks

abstract:
  Discovering and characterizing the large-scale topological features in
empirical networks are crucial steps in understanding how complex systems
function. However, most existing methods used to obtain the modular structure
of networks suffer from serious problems, such as being oblivious to the
statistical evidence supporting the discovered patterns, which results in the
inability to separate actual structure from noise. In addition to this, one
also observes a resolution limit on the size of communities, where smaller but
well-defined clusters are not detectable when the network becomes large. This
phenomenon occurs not only for the very popular approach of modularity
optimization, which lacks built-in statistical validation, but also for more
principled methods based on statistical inference and model selection, which do
incorporate statistical validation in a formally correct way. Here we construct
a nested generative model that, through a complete description of the entire
network hierarchy at multiple scales, is capable of avoiding this limitation,
and enables the detection of modular structure at levels far beyond those
possible with current approaches. Even with this increased resolution, the
method is based on the principle of parsimony, and is capable of separating
signal from noise, and thus will not lead to the identification of spurious
modules even on sparse networks. Furthermore, it fully generalizes other
approaches in that it is not restricted to purely assortative mixing patterns,
directed or undirected graphs, and ad hoc hierarchical structures such as
binary trees. Despite its general character, the approach is tractable, and can
be combined with advanced techniques of community detection to yield an
efficient algorithm that scales well for very large networks.

categories: physics.data-an cond-mat.dis-nn cond-mat.stat-mech cs.SI physics.soc-ph stat.ML


title:
Efficient Monte Carlo and greedy heuristic for the inference of
  stochastic block models

abstract:
  We present an efficient algorithm for the inference of stochastic block
models in large networks. The algorithm can be used as an optimized Markov
chain Monte Carlo (MCMC) method, with a fast mixing time and a much reduced
susceptibility to getting trapped in metastable states, or as a greedy
agglomerative heuristic, with an almost linear $O(N\ln^2N)$ complexity, where
$N$ is the number of nodes in the network, independent on the number of blocks
being inferred. We show that the heuristic is capable of delivering results
which are indistinguishable from the more exact and numerically expensive MCMC
method in many artificial and empirical networks, despite being much faster.
The method is entirely unbiased towards any specific mixing pattern, and in
particular it does not favor assortative community structures.

categories: physics.data-an cond-mat.stat-mech cs.SI physics.comp-ph stat.ML


title:
Search for surface magnetic fields in Mira stars. First detection in chi
  Cyg

abstract:
  In order to complete the knowledge of the magnetic field and of its influence
during the transition from Asymptotic Giant Branch to Planetary Nebulae stages,
we have undertaken a search for magnetic fields at the surface of Mira stars.
We used spectropolarimetric observations, collected with the Narval instrument
at TBL, in order to detect - with Least Squares Deconvolution method - a Zeeman
signature in the visible part of the spectrum. We present the first
spectropolarimetric observations of the S-type Mira star chi Cyg, performed
around its maximum light. We have detected a polarimetric signal in the Stokes
V spectra and we have established its Zeeman origin. We claim that it is likely
to be related to a weak magnetic field present at the photospheric level and in
the lower part of the stellar atmosphere. We have estimated the strength of its
longitudinal component to about 2-3 Gauss. This result favors a 1/r law for the
variation of the magnetic field strength across the circumstellar envelope of
chi Cyg. This is the first detection of a weak magnetic field at the stellar
surface of a Mira star and we discuss its origin in the framework of shock
waves periodically propagating throughout the atmosphere of these radially
pulsating stars. At the date of our observations of chi Cyg, the shock wave
reaches its maximum intensity, and it is likely that the shock amplifies a weak
stellar magnetic field during its passage through the atmosphere. Without such
an amplification by the shock, the magnetic field strength would have been too
low to be detected. For the first time, we also report strong Stokes Q and U
signatures (linear polarization) centered onto the zero velocity (i.e., at the
shock front position). They seem to indicate that the radial direction would be
favored by the shock during its propagation throughout the atmosphere.


title:
Comparison of $H\to\ell\bar{\ell}\gamma$ and $H\to\gamma\,Z,
  Z\to\ell\bar{\ell}$ including the ATLAS cuts

abstract:
  A precise comparison is made between the Dalitz decay
$H\to\ell\bar{\ell}\gamma$ and the two body decay $H\to\gamma
Z,Z\to\ell\bar{\ell}$ for electrons and for muons including experimental cuts
appropriate for the ATLAS detector. The widths for these two processes differ
by 8% for electrons and 3% for muons. Given that there remain QCD radiative
corrections of this order that are not included, this suggests that the
isolation of the Dalitz decay will be challenging.


title: On the crossing number of some complete multipartite graphs

abstract:
  In this paper, we find the crossing number of the complete multipartite
graphs $K_{1,1,1,1,n}$, $K_{1,2,2,n}$, $K_{1,1,1,2,n}$ and $K_{1,4,n}$.


title:
Harnack Inequalities for SDEs with Multiplicative Noise and Non-regular
  Drift

abstract:
  The log-Harnack inequality and Harnack inequality with powers for semigroups
associated to SDEs with non-degenerate diffusion coefficient and non-regular
time-dependent drift coefficient are established, based on the recent papers
\cite{Flandoli, Zhang11}. We consider two cases in this work: (1) the drift
fulfills the LPS-type integrability, and (2) the drift is uniformly H\"older
continuous with respect to the spatial variable. Finally, by using explicit
heat kernel estimates for the stable process with drift, the Harnack inequality
for the stochastic differential equation driven by symmetric stable process is
also proved.


title: Two Approaches to Sidorenko's Conjecture

abstract:
  Sidorenko's conjecture states that for every bipartite graph $H$ on
$\{1,\cdots,k\}$, $\int \prod_{(i,j)\in E(H)} h(x_i, y_j) d\mu^{|V(H)|} \ge
\left( \int h(x,y) \,d\mu^2 \right)^{|E(H)|}$ holds, where $\mu$ is the
Lebesgue measure on $[0,1]$ and $h$ is a bounded, non-negative, symmetric,
measurable function on $[0,1]^2$. An equivalent discrete form of the conjecture
is that the number of homomorphisms from a bipartite graph $H$ to a graph $G$
is asymptotically at least the expected number of homomorphisms from $H$ to the
Erd\H{o}s-R\'{e}nyi random graph with the same expected edge density as $G$. In
this paper, we present two approaches to the conjecture. First, we introduce
the notion of tree-arrangeability, where a bipartite graph $H$ with bipartition
$A \cup B$ is tree-arrangeable if neighborhoods of vertices in $A$ have a
certain tree-like structure. We show that Sidorenko's conjecture holds for all
tree-arrangeable bipartite graphs. In particular, this implies that Sidorenko's
conjecture holds if there are two vertices $a_1, a_2$ in $A$ such that each
vertex $a \in A$ satisfies $N(a) \subseteq N(a_1)$ or $N(a) \subseteq N(a_2)$,
and also implies a recent result of Conlon, Fox, and Sudakov \cite{CoFoSu}.
Second, if $T$ is a tree and $H$ is a bipartite graph satisfying Sidorenko's
conjecture, then it is shown that the Cartesian product $T \Box H$ of $T$ and
$H$ also satisfies Sidorenko's conjecture. This result implies that, for all $d
\ge 2$, the $d$-dimensional grid with arbitrary side lengths satisfies
Sidorenko's conjecture.


title:
Numerical comparison of a constrained path ensemble and a driven
  quasisteady state

abstract:
  We investigate the correspondence between a non-equilibrium ensemble defined
via the distribution of phase-space paths of a Hamiltonian system, and a system
driven into a steady-state by non-equilibrium boundary conditions. To discover
whether the non-equilibrium path ensemble adequately describes the physics of a
driven system, we measure transition rates in a simple one-dimensional model of
rotors with Newtonian dynamics and purely conservative interactions. We compare
those rates with known properties of the non-equilibrium path ensemble. In
doing so, we establish effective protocols for the analysis of transition rates
in non-equilibrium quasi-steady states. Transition rates between potential
wells and also between phase-space elements are studied, and found to exhibit
distinct properties, the more coarse-grained potential wells being effectively
further from equilibrium. In all cases the results from the boundary-driven
system are close to the path-ensemble predictions, but the question of
equivalence of the two remains open.


title:
Insensitivity of Ion Motional Heating Rate to Trap Material over a Large
  Temperature Range

abstract:
  We present measurements of trapped-ion motional-state heating rates in
niobium and gold surface-electrode ion traps over a range of trap-electrode
temperatures from approximately 4 K to room temperature (295 K) in a single
apparatus. Using the sideband-ratio technique after resolved-sideband cooling
of single ions to the motional ground state, we find low-temperature heating
rates more than two orders of magnitude below the room-temperature values and
approximately equal to the lowest measured heating rates in similarly-sized
cryogenic traps. We find similar behavior in the two very different electrode
materials, suggesting that the anomalous heating process is dominated by
non-material-specific surface contaminants. Through precise control of the
temperature of cryopumping surfaces, we also identify conditions under which
elastic collisions with the background gas can lead to an apparent steady
heating rate, despite rare collisions.


title: Ambiguity of certain Chow-Kuenneth projectors

abstract:
  We show that the ambiguity of Murre's Chow-Kuenneth projector for degree 1
has certain good properties, assuming only that it factors through a Chow
motive of a smooth irreducible curve. This is compatible with a picture
obtained by using Beilinson's conjectural mixed motives, and implies for
instance the independence of the Chow motive defined by the middle
Chow-Kuenneth projector for surfaces.


title: Vaccination models and optimal control strategies to dengue

abstract:
  As the development of a dengue vaccine is ongoing, we simulate an
hypothetical vaccine as an extra protection to the population. In a first
phase, the vaccination process is studied as a new compartment in the model,
and different ways of distributing the vaccines investigated: pediatric and
random mass vaccines, with distinct levels of efficacy and durability. In a
second step, the vaccination is seen as a control variable in the
epidemiological process. In both cases, epidemic and endemic scenarios are
included in order to analyze distinct outbreak realities.


title: d+Au Hadron Correlation Measurements from PHENIX

abstract:
  Recent observations of extended pseudorapidity correlations at the LHC in p+p
and p+Pb collisions are of great interest. Here we present related re- sults
from d+Au collisions at PHENIX. We present the observed v2 and discuss the
possible origin in the geometry of the collision region. We also present new
measurements of the pseudorapidity dependence of the ridge in d+Au collision.
Future plans to clarify the role of geometry in small collision systems using
3He+Au collisions are discussed.


title: ImageSpirit: Verbal Guided Image Parsing

abstract:
  Humans describe images in terms of nouns and adjectives while algorithms
operate on images represented as sets of pixels. Bridging this gap between how
humans would like to access images versus their typical representation is the
goal of image parsing, which involves assigning object and attribute labels to
pixel. In this paper we propose treating nouns as object labels and adjectives
as visual attribute labels. This allows us to formulate the image parsing
problem as one of jointly estimating per-pixel object and attribute labels from
a set of training images. We propose an efficient (interactive time) solution.
Using the extracted labels as handles, our system empowers a user to verbally
refine the results. This enables hands-free parsing of an image into pixel-wise
object/attribute labels that correspond to human semantics. Verbally selecting
objects of interests enables a novel and natural interaction modality that can
possibly be used to interact with new generation devices (e.g. smart phones,
Google Glass, living room devices). We demonstrate our system on a large number
of real-world images with varying complexity. To help understand the tradeoffs
compared to traditional mouse based interactions, results are reported for both
a large scale quantitative evaluation and a user study.


title:
Integrable structure of Quantum Field Theory: Classical flat connections
  versus quantum stationary states

abstract:
  We establish a correspondence between an infinite set of special solutions of
the (classical) modified sinh-Gordon equation and a set of stationary states in
the finite-volume Hilbert space of the integrable 2D QFT invented by V.A.
Fateev. The modified sinh-Gordon equation arise in this case as a
zero-curvature condition for a class of multivalued connections of the
punctured Riemann sphere, similarly to Hitchin's self-duality equations. The
proposed correspondence between the classical and quantum integrable systems
provides a powerful tool for deriving functional and integral equations which
determine the full spectrum of local integrals of motion for massive QFT in a
finite volume. Potential applications of our results to the problem of
non-perturbative quantization of classically integrable non-linear sigma models
are briefly discussed.


title:
Exact Results on Itinerant Ferromagnetism in Multi-orbital Systems on
  Square and Cubic Lattices

abstract:
  We study itinerant ferromagnetism in multi-orbital Hubbard models in certain
two-dimensional square and three-dimensional cubic lattices. In the strong
coupling limit where doubly occupied orbitals are not allowed, we prove that
the fully spin-polarized states are the unique ground states, apart from the
trivial spin degeneracies, for a large region of fillings factors. Possible
applications to p-orbital bands with ultra-cold fermions in optical lattices,
and electronic 3d-orbital bands in transition-metal oxides, are discussed.


title: Electrotactile vision substitution for 3D trajectory following

abstract:
  Navigation for blind persons represents a challenge for researchers in vision
substitution. In this field, one of the used techniques to navigate is
guidance. In this study, we develop a new approach for 3D trajectory following
in which the requested task is to track a light path using computer input
devices (keyboard and mouse) or a rigid body handled in front of a stereoscopic
camera. The light path is visualized either on direct vision or by way of a
electro-stimulation device, the Tongue Display Unit, a 12x12 matrix of
electrodes. We improve our method by a series of experiments in which the
effect of the modality of perception and that of the input device. Preliminary
results indicated a close correlation between the stimulated and recorded
trajectories.


title:
An algorithm for variable density sampling with block-constrained
  acquisition

abstract:
  Reducing acquisition time is of fundamental importance in various imaging
modalities. The concept of variable density sampling provides a nice framework
to achieve this. It was justified recently from a theoretical point of view in
the compressed sensing (CS) literature. Unfortunately, the sampling schemes
suggested by current CS theories may not be relevant since they do not take the
acquisition constraints into account (for example, continuity of the
acquisition trajectory in Magnetic Resonance Imaging - MRI). In this paper, we
propose a numerical method to perform variable density sampling with block
constraints. Our main contribution is to propose a new way to draw the blocks
in order to mimic CS strategies based on isolated measurements. The basic idea
is to minimize a tailored dissimilarity measure between a probability
distribution defined on the set of isolated measurements and a probability
distribution defined on a set of blocks of measurements. This problem turns out
to be convex and solvable in high dimension. Our second contribution is to
define an efficient minimization algorithm based on Nesterov's accelerated
gradient descent in metric spaces. We study carefully the choice of the metrics
and of the prox function. We show that the optimal choice may depend on the
type of blocks under consideration. Finally, we show that we can obtain better
MRI reconstruction results using our sampling schemes than standard strategies
such as equiangularly distributed radial lines.


title: Tunable phonon-induced transparency in bilayer graphene nanoribbons

abstract:
  In the phenomenon of electromagnetically induced transparency1 (EIT) of a
three-level atomic system, the linear susceptibility at the dipole-allowed
transition is canceled through destructive interference of the direct
transition and an indirect transition pathway involving a meta-stable level,
enabled by optical pumping. EIT not only leads to light transmission at
otherwise opaque atomic transition frequencies, but also results in the slowing
of light group velocity and enhanced optical nonlinearity. In this letter, we
report an analogous behavior, denoted as phonon-induced transparency (PIT), in
AB-stacked bilayer graphene nanoribbons. Here, light absorption due to the
plasmon excitation is suppressed in a narrow window due to the coupling with
the infrared active {\Gamma}-point optical phonon, whose function here is
similar to that of the meta-stable level in EIT of atomic systems. We further
show that PIT in bilayer graphene is actively tunable by electrostatic gating,
and estimate a maximum slow light factor of around 500 at the phonon frequency
of 1580 cm-1, based on the measured spectra. Our demonstration opens an avenue
for the exploration of few-photon non-linear optics and slow light in this
novel two-dimensional material, without external optical pumping and at room
temperature.


title: Non-amenability of R.Thompson's group F

abstract: We present a proof of non-amenability of R.Thompson's group F.


title: Geometry-induced Casimir suspension of oblate bodies in fluids

abstract:
  We predict that a low-permittivity oblate body (disk-shaped object) above a
thin metal substrate (plate with a hole) immersed in a fluidof intermediate
permittivity will experience a meta-stable equilibrium (restoring force) near
the center of the hole. Stability is the result of a geometry-induced
transition in the sign of the force, from repulsive to attractive, that occurs
as the disk approaches the hole---in planar or nearly-planar geometries, the
same material combination yields a repulsive force at all separations in
accordance with the Dzyaloshinskii--Lifshitz--Pitaevskii condition of
fluid-induced repulsion between planar bodies. We explore the stability of the
system with respect to rotations and lateral translations of the disks, and
demonstrate interesting transitions (bifurcations) in the rotational stability
of the disks as a function of their size. Finally, we consider the reciprocal
situation in which the disk--plate materials are interchanged, and find that in
this case the system also exhibits meta-stability. The forces in the system are
sufficiently large to be observed in experiments and should enable measurements
based on the diffusion dynamics of the suspended bodies.


title:
Stable One-Dimensional Integral Representations of One-Loop N-Point
  Functions in the General Massive Case: I - Three Point Functions

abstract:
  In this article we provide representations for the one-loop three point
functions in 4 and 6 dimensions in the general case with complex masses. The
latter are part of the GOLEM library used for the computation of one-loop
multileg amplitudes. These representations are one-dimensional integrals
designed to be free of instabilites induced by inverse powers of Gram
determinants, therefore suitable for stable numerical implementations.


title: Modelling Accretion in Transitional Disks

abstract:
  Transitional disks are protoplanetary disk around young stars that display
inner holes in the dust distribution within a few AU, which is accompanied
nevertheless by some gas accretion onto the central star. These cavities could
possibly be created by the presence of one or more massive planets. If the gap
is created by planets and gas is still present in it, then there should be a
flow of gas past the planet into the inner region. It is our goal to study the
mass accretion rate into the gap and in particular the dependency on the
planet's mass and the thermodynamic properties of the disk. We performed 2D
hydro simulations for disks with embedded planets. We added radiative cooling
from the disk surfaces, radiative diffusion in the disk midplane, and stellar
irradiation to the energy equation to have more realistic models. The mass flow
rate into the gap region depends, for given disk thermodynamics,
non-monotonically on the mass of the planet. Generally, more massive planets
open wider and deeper gaps which would tend to reduce the mass accretion into
the inner cavity. However, for larger mass planets the outer disk becomes
eccentric and the mass flow rate is enhanced over the low mass cases. As a
result, for the isothermal disks the mass flow is always comparable to the
expected mass flow of unperturbed disks M_d, while for more realistic radiative
disks the mass flow is very small for low mass planets (<= 4 M_jup) and about
50% for larger planet masses. For the radiative disks that critical planet mass
for the disk to become eccentric is much larger that in the isothermal case.
Massive embedded planets can reduce the mass flow across the gap considerably,
to values of about an order of magnitude smaller than the standard disk
accretion rate, and can be responsible for opening large cavities. The
remaining mass flow into the central cavity is in good agreement with the
observations.


title: Analyzing User Behavior across Social Sharing Environments

abstract:
  In this work we present an in-depth analysis of the user behaviors on
different Social Sharing systems. We consider three popular platforms, Flickr,
Delicious and StumbleUpon, and, by combining techniques from social network
analysis with techniques from semantic analysis, we characterize the tagging
behavior as well as the tendency to create friendship relationships of the
users of these platforms. The aim of our investigation is to see if (and how)
the features and goals of a given Social Sharing system reflect on the behavior
of its users and, moreover, if there exists a correlation between the social
and tagging behavior of the users. We report our findings in terms of the
characteristics of user profiles according to three different dimensions: (i)
intensity of user activities, (ii) tag-based characteristics of user profiles,
and (iii) semantic characteristics of user profiles.


title: Statistical likelihood methods in finance

abstract:
  It is known from previous work of the authors that non-negative arbitrage
free price processes in finance can be described in terms of filtered
likelihood processes of statistical experiments and vice versa. The present
paper summarizes and outlines some similarities between finance and the
statistical likelihood theory of Le Cam. Options are linked to statistical
tests of the underlying experiments. In particular, some price formulas for
options are expressed by the power of related tests. In special cases the
dynamics of power functions for filtered likelihood processes can be used to
establish trading strategies which lead to formulas for the Greeks Delta and
Gamma. Moreover statistical arguments are then used to establish a discrete
approximation of continuous time trading strategies. It is explained that Ito
type financial models correspond to hazard based survival models in statistics.
Also price processes given by a geometric fractional Brownian motion have a
statistical counterpart in terms of the likelihood theory of Gaussian
statistical experiments.


title: Recursive encoding and decoding of the noiseless subsystem for qudits

abstract:
  We give a full explanation of the noiseless subsystem that protects a
single-qubit against collective errors and the corresponding recursive scheme
described by C.-K. Li et. al. [Phys. Rev. A 84, 044301 (2011)] from a
representation theory point of view. Furthermore, we extend the construction to
qudits under the influence of collective SU($d$) errors. We find that under
this recursive scheme, the asymptotic encoding rate is $1/d$.


title: A Converging Lagrangian Curvature Flow in the Space of Oriented Lines

abstract:
  Under mean radius of curvature flow, a closed convex surface in Euclidean
space is known to expand exponentially to infinity. In the 3-dimensional case
we prove that the oriented normals to the flowing surface converge to the
oriented normals of a round sphere whose centre is determined by the initial
surface.
  To prove this we show that the oriented normal lines, considered as a surface
in the space of all oriented lines, evolve by a parabolic flow which preserves
the Lagrangian condition. Moreover, this flow converges to a holomorphic
Lagrangian section, which form the set of oriented lines through a point.
  The coordinates of this centre point are projections of the support function
into the first non-zero eigenspace of the spherical Laplacian and are given by
explicit integrals of initial surface data.


title:
Complexity, economic science and possible economic benefits of climate
  change mitigation policy

abstract:
  Conventional economic analysis of stringent climate change mitigation policy
generally concludes various levels of economic slowdown as a result of
substantial spending on low carbon technology. Equilibrium economics however
could not explain or predict the current economic crisis, which is of financial
nature. Meanwhile the economic impacts of climate policy find their source
through investments for the diffusion of environmental innovations, in parts a
financial problem. Here, we expose how results of economic analysis of climate
change mitigation policy depend entirely on assumptions and theory concerning
the finance of the diffusion of innovations, and that in many cases, results
are simply re-iterations of model assumptions. We show that, while equilibrium
economics always predict economic slowdown, methods using non-equilibrium
approaches suggest the opposite could occur. We show that the solution to
understanding the economic impacts of reducing greenhouse gas emissions lies
with research on the dynamics of the financial sector interacting with
innovation and technology developments, economic history providing powerful
insights through important analogies with previous historical waves of
innovation.


title:
A regularisation approach to causality theory for $C^{1,1}$-Lorentzian
  metrics

abstract:
  We show that many standard results of Lorentzian causality theory remain
valid if the regularity of the metric is reduced to $C^{1,1}$. Our approach is
based on regularisations of the metric adapted to the causal structure.


title: Terahertz out-of-plane resonances due to spin-orbit coupling

abstract:
  A microscopic kinetic theory is developed which allows to investigate
non-Abelian SU(2) systems interacting with meanfields and spin-orbit coupling
under magnetic fields in one, two, and three dimensions. The coupled kinetic
equations for the scalar and spin components are presented and linearized with
respect to an external electric field. The dynamical classical and quantum Hall
effect are described in this way as well as the anomalous Hall effect where a
new symmetric dynamical contribution to the conductivity is presented. The
coupled density and spin response functions to an electric field are derived
including arbitrary magnetic fields. The magnetic field induces a staircase
structure at frequencies of the Landau levels. It is found that for linear
Dresselhaus and Rashba spin-orbit coupling a dynamical out-of-plane spin
response appears at these Landau level frequencies establishing terahertz
resonances.


title: Extreme waves statistics for Ablowitz-Ladik system

abstract:
  We examine statistics of waves for the problem of modulation instability
development in the framework of discrete integrable Ablowitz-Ladik (AL) system.
Modulation instability depends on one free parameter h that has the meaning of
the coupling between the nodes on the lattice. For strong coupling h<<1 the
probability density functions (PDFs) for waves amplitudes coincide with that
for the continuous classical Nonlinear Schrodinger (NLS) equation; the PDFs for
both systems are very close to Rayleigh ones. When the coupling is weak h~1,
there appear highly localized waves with very large amplitudes, that
drastically change the PDFs to significantly non-Rayleigh ones, with so-called
"fat tails" when the probability of a large wave occurrence is by several
orders of magnitude higher than that predicted by the linear theory. Evolution
of amplitudes for such rogue waves with time is similar to that of the
Peregrine solution for the classical NLS equation.


title: Categorical duality for Yetter-Drinfeld algebras

abstract:
  We study tensor structures on (Rep G)-module categories defined by actions of
a compact quantum group G on unital C*-algebras. We show that having a tensor
product which defines the module structure is equivalent to enriching the
action of G to the structure of a braided-commutative Yetter-Drinfeld algebra.
This shows that the category of braided-commutative Yetter-Drinfeld
G-C*-algebras is equivalent to the category of generating unitary tensor
functors from Rep G into C*-tensor categories. To illustrate this equivalence,
we discuss coideals of quotient type in C(G), Hopf-Galois extensions and
noncommutative Poisson boundaries.


title: Radio Observations of Supernova 1987A

abstract:
  Supernovae and their remnants are believed to be prodigious sources of
Galactic cosmic rays and interstellar dust. Understanding the mechanisms behind
their surprisingly high production rate is helped by the study of nearby young
supernova remnants. There has been none better in modern times than SN1987A,
for which radio observations have been made for over a quarter of a century. We
review extensive observations made with the Australia Telescope Compact Array
(ATCA) at centimetre wavelengths. Emission at frequencies from 1 to 100 GHz is
dominated by synchrotron radiation from an outer shock front which has been
growing exponentially in strength from day 3000, and is currently sweeping
around the circumstellar ring at about 4000 km s$^{-1}$. Three dimensional
models of the propagation of the shock into the circumstellar medium are able
to reproduce the main observational features of the remnant, and their
evolution. We find that up to 4% of the electrons encountered by the shock are
accelerated to relativistic energies. High-frequency ALMA observations will
break new ground in the understanding of dust and molecule production.


title: Recent results from BESIII experiment

abstract:
  In this talk, we present a selection of recent results from BESIII
collaboration, including observation of the charmoniumlike states, Zc(3900),
Zc(4020) and Zc(4025); observation of e+e- -> gamma X(3872); partial wave
analysis of J/psi -> gamma eta eta; measurement of D+ -> mu+ nu and D0 -> K- e+
nu, pi- e+ nu. The results are based on the data samples collected with the
BESIII detector at central-of-mass energies from 3.900 to 4.420 GeV, and at the
energies of J/psi and psi(3770) resonances.


title: On the partition functions of higher spin black holes

abstract:
  We reconsider black hole solutions of D = 3 higher-spin gravity in the
$hs[\lambda]\oplus hs[\lambda]$ Chern-Simons formulation. A suitable
generalisation of the BTZ black hole has a spin-3 chemical potential $\alpha$,
and non-zero values of all the conserved charges associated with the asymptotic
$\mathcal W_\infty[\lambda]$ symmetry. We extend the available perturbative
expansion of the partition function to order $\mathcal O(\alpha^{18})$ for
generic values of the $\lambda$ parameter. The result matches the CFT
prediction at $\lambda=0$ and at $\lambda=1$ where we provide the exact
all-order expansion of the partition function. The perturbative series is then
analysed in the interesting non-trivial limit $\lambda\to\infty$ and we derive
the exact analytical expressions of the partition function and the spin-4
charge in closed form as functions of $\alpha$. Also, the first subleading
correction at large $\lambda$ is shown to be simply related to the leading
contribution.


title: The Danger of a Big Data Episteme and the Need to Evolve GIS

abstract:
  The emergence of "Big Data" as a dominant technology meme challenges
Geography's technical underpinnings, found in GIS, while engaging the
discipline in a conversation about the meme's impact on society. This allows
scholars to engage collaboratively from both a computationally quantitative and
critically qualitative perspective. For Geography there is an opportunity to
point out these shortcomings through critical appraisals of "Big Data" and its
reflection of society. Complimentarily this opens the door to developing
methodologies that will allow for a more realistic interpretation of "Big Data"
analysis in the context of an unfiltered societal view.


title: Delay on broadcast erasure channels under random linear combinations

abstract:
  We consider a transmitter broadcasting random linear combinations (over a
field of size $d$) formed from a block of $c$ packets to a collection of $n$
receivers, where the channels between the transmitter and each receiver are
independent erasure channels with reception probabilities $\mathbf{q} =
(q_1,\ldots,q_n)$. We establish several properties of the random delay until
all $n$ receivers have recovered all $c$ packets, denoted $Y_{n:n}^{(c)}$.
First, we provide lower and upper bounds, exact expressions, and a recurrence
for the moments of $Y_{n:n}^{(c)}$. Second, we study the delay per packet
$Y_{n:n}^{(c)}/c$ as a function of $c$, including the asymptotic delay (as $c
\to \infty$), and monotonicity (in $c$) properties of the delay per packet.
Third, we employ extreme value theory to investigate $Y_{n:n}^{(c)}$ as a
function of $n$ (as $n \to \infty$). Several results are new, some results are
extensions of existing results, and some results are proofs of known results
using new (probabilistic) proof techniques.


title: Optical conductivity of a strong-coupling polaron

abstract:
  The polaron optical conductivity is derived within the strong-coupling
expansion, which is asymptotically exact in the strong-coupling limit. The
polaron optical conductivity band is provided by the multiphonon optical
transitions. The polaron optical conductivity spectra calculated within our
analytic strong-coupling approach and the numerically accurate Diagrammatic
Quantum Monte Carlo (DQMC) data are in a good agreement with each other at
large $\alpha \gtrapprox 9$.


title: Reactions between cold methyl halide molecules and alkali-metal atoms

abstract:
  We investigate the potential energy surfaces and activation energies for
reactions between methyl halide molecules CH$_{3}X$ ($X$ = F, Cl, Br, I) and
alkali-metal atoms $A$ ($A$ = Li, Na, K, Rb) using high-level {\it ab initio}
calculations. We examine the anisotropy of each intermolecular potential energy
surface (PES) and the mechanism and energetics of the only available exothermic
reaction pathway, ${\rm CH}_{3}X+A\rightarrow{\rm CH}_{3}+AX$. The region of
the transition state is explored using two-dimensional PES cuts and estimates
of the activation energies are inferred. Nearly all combinations of methyl
halide and alkali-metal atom have positive barrier heights, indicating that
reactions at low temperatures will be slow.


title: Submodular Stochastic Probing on Matroids

abstract:
  In a stochastic probing problem we are given a universe $E$, where each
element $e \in E$ is active independently with probability $p_e$, and only a
probe of e can tell us whether it is active or not. On this universe we execute
a process that one by one probes elements --- if a probed element is active,
then we have to include it in the solution, which we gradually construct.
Throughout the process we need to obey inner constraints on the set of elements
taken into the solution, and outer constraints on the set of all probed
elements. This abstract model was presented by Gupta and Nagarajan (IPCO '13),
and provides a unified view of a number of problems. Thus far, all the results
falling under this general framework pertain mainly to the case in which we are
maximizing a linear objective function of the successfully probed elements. In
this paper we generalize the stochastic probing problem by considering a
monotone submodular objective function. We give a $(1 - 1/e)/(k_{in} +
k_{out}+1)$-approximation algorithm for the case in which we are given $k_{in}$
matroids as inner constraints and $k_{out}$ matroids as outer constraints.
Additionally, we obtain an improved $1/(k_{in} + k_{out})$-approximation
algorithm for linear objective functions.


title: Chemical potentials and parity breaking: the Nambu-Jona-Lasinio model

abstract:
  We consider the "two flavour" Nambu--Jona-Lasinio model in the presence of a
vector and an axial external chemical potentials and study the phase structure
of the model at zero temperature. The Nambu--Jona-Lasinio model is often used
as a toy replica of QCD and it is therefore interesting to explore the
consequences of adding external vector and axial chemical potentials in this
model, mostly motivated by claims that such external drivers could trigger a
phase where parity could be broken in QCD. We are also motivated by some
lattice analysis that attempt to understand the nature of the so-called Aoki
phase using this simplified model. Analogies and differences with the expected
behaviour in QCD are discussed and the limitations of the model are pointed
out.


title:
The superluminous supernova PS1-11ap: bridging the gap between low and
  high redshift

abstract:
  We present optical photometric and spectroscopic coverage of the
superluminous supernova (SLSN) PS1-11ap, discovered with the Pan-STARRS1 Medium
Deep Survey at z = 0.524. This intrinsically blue transient rose slowly to
reach a peak magnitude of M_u = -21.4 mag and bolometric luminosity of 8 x
10^43 ergs^-1 before settling onto a relatively shallow gradient of decline.
The observed decline is significantly slower than those of the superluminous
type Ic SNe which have been the focus of much recent attention. Spectroscopic
similarities with the lower redshift SN2007bi and a decline rate similar to
56Co decay timescale initially indicated that this transient could be a
candidate for a pair instability supernova (PISN) explosion. Overall the
transient appears quite similar to SN2007bi and the lower redshift object
PTF12dam. The extensive data set, from 30 days before peak to 230 days after,
allows a detailed and quantitative comparison with published models of PISN
explosions. We find that the PS1-11ap data do not match these model explosion
parameters well, supporting the recent claim that these SNe are not pair
instability explosions. We show that PS1-11ap has many features in common with
the faster declining superluminous Ic supernovae and the lightcurve evolution
can also be quantitatively explained by the magnetar spin down model. At a
redshift of z = 0.524 the observer frame optical coverage provides
comprehensive restframe UV data and allows us to compare it with the
superluminous SNe recently found at high redshifts between z = 2-4. While these
high-z explosions are still plausible PISN candidates, they match the
photometric evolution of PS1-11ap and hence could be counterparts to this lower
redshift transient.


title: A selection-quotient process for packed word Hopf algebra

abstract:
  In this paper, we define a Hopf algebra structure on the vector space spanned
by packed words using a selection-quotient coproduct. We show that this algebra
is free on its irreducible packed words. Finally, we give some brief
explanations on the Maple codes we have used.


title: Non-uniqueness of Weak Solutions to the Wave Map Problem

abstract:
  In this note we show that weak solutions to the wave map problem in the
energy-supercritical dimension 3 are not unique. On the one hand, we find weak
solutions using the penalization method introduced by Shatah and show that they
satisfy a local energy inequality. On the other hand we build on a special
harmonic map to construct a weak solution to the wave map problem, which
violates this energy inequality.
  Finally we establish a local weak-strong uniqueness argument in the spirit of
Struwe which we employ to show that one may even have a failure of uniqueness
for a Cauchy problem with a stationary solution. We thus obtain a result
analogous to the one of Coron for the case of the heat flow of harmonic maps.


title: Exact Nonequilibrium Steady State of an Open Hubbard Chain

abstract:
  We discuss current carrying non-equilibrium steady state of an open fermionic
Hubbard chain that is strongly driven by markovian incoherent processes
localized at the chain ends. An explicit form of exact many-body density
operator for any value of the coupling parameter is presented. The structure of
a matrix product form of the solution is encoded in terms of a novel
diagrammatic technique which should allow for generalization to other
integrable non-equillibrium models.

categories: quant-ph cond-mat.stat-mech cond-mat.str-el nlin.SI


title: Efficient computation of Rankin p-adic L-functions

abstract:
  We present an efficient algorithm for computing certain special values of
Rankin triple product $p$-adic L-functions and give an application of this to
the explicit construction of rational points on elliptic curves.


title: A realistic renormalizable supersymmetric E6 model

abstract:
  A complete realistic model based on the supersymmetric version of $E_6$ is
presented. It consists of three copies of matter 27, and a Higgs sector made of
$2\times(27+\bar{27})+351'+\bar{351'}$ representations. An analytic solution to
the equations of motion is found which spontaneously breaks the gauge group
into the Standard Model. The light fermion mass matrices are written down
explicitly as non-linear functions of three Yukawa matrices. This contribution
is based on Ref. [1].


title:
Electroweak and Conformal Symmetry Breaking by a Strongly Coupled Hidden
  Sector

abstract:
  The LHC and other experiments show so far no sign of new physics and
long-held beliefs about naturalness should be critically reexamined. We discuss
therefore in this paper a model with a combined breaking of conformal and
electroweak symmetry by a strongly coupled hidden sector. Even though the
conformal symmetry is anomalous, this may still provide an explanation of the
smallness of electroweak scale compared to the Planck scale. Specifically we
start from a classically conformal model, in which a strongly coupled hidden
sector undergoes spontaneous chiral symmetry breaking. A coupling via a real
scalar field transmits the breaking scale to the Standard Model Higgs and
triggers electroweak symmetry breaking. The model contains dark matter
candidates in the form of dark pions, whose stability is being guaranteed by
the flavor symmetry of hidden quark sector. We study its relic abundance and
direct detection prospects with the Nambu-Jona-Lasinio method and discuss the
phase transition in the dark sector as well as in the electroweak sector.


title:
Quantum Kerr tunneling vacua on a $(D{\bar D})_4$-brane: An emergent
  Kerr black hole in five dimensions

abstract:
  We revisit a non-perturbative space-time curvature theory, underlying a two
form U(1) gauge dynamics, on a D4-brane. In particular, two different gauge
choices for a two form are explored underlying the dynamics of a geometric
torsion in a second order formalism. We obtain two non-extremal quantum Kerr
geometries in five dimensions on a pair of $(D{\bar D})_4$-brane in a type IIA
superstring theory. The quantum vacua are described by a vanishing torsion in a
gauge choice, underlying a geometric realization, on a non-BPS brane. It is
argued that the quantum Kerr vacua undergo tunneling and lead to a five
dimensional Kerr black hole in Einstein vacuum. A low energy limit in the
quantum Kerr vacua further re-assures an emergent Kerr black hole.


title: Exact theory of intermediate phases in two dimensions

abstract:
  We show how field theory yields the exact description of intermediate phases
in the scaling limit of two-dimensional statistical systems at a first order
phase transition point. The ability of a third phase to form an intermediate
wetting layer or only isolated bubbles is explicitly related to the spectrum of
excitations of the field theory. The order parameter profiles are determined
and interface properties such as passage probabilities and internal structure
are deduced from them. The theory is illustrated through the application to the
q-state Potts model and Ashkin-Teller model. The latter is shown to provide the
first exact solution of a bulk wetting transition.

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


title:
Update on the Sea Contributions to Hadron Electric Polarizabilities
  through Reweighting

abstract:
  We present the results of a reweighting calculation to compute the
contribution of the charged quark sea to the neutron electric polarizability.
The chief difficulty is the stochastic estimation of weight factors, and we
present a hopping parameter expansion-based technique for reducing the
stochastic noise, along with a discussion of why this particular reweighting is
so difficult. We used this technique to estimate weight factors for 300
configurations of nHYP-clover fermions and compute the neutron polarizability,
but the reweighting greatly inflates the overall statistical error, driven by
the stochastic noise in the weight factors.


title:
Neutron-skin effects in isobaric yield ratio for mirror nuclei in
  statistical abrasion-ablation model

abstract:
  \item[Purpose] We suppose that the IYR(m) depends on the neutron-skin
thickness ($\delta_{np}$) of the projectile, and check the idea of whether the
neutron-skin thickness effects can fully explain the systematic dependence of
the IYR(m). \item[Methods] A modified statistical abrasion-ablation model is
used to calculate the reactions induced by projectiles of three series.
\item[Results] The IYR(m) shows a distribution of a linear part in the
small-$x$ fragments, and a nonlinear part in the large-$x$ fragments. The
linear part of IYR(m) is fitted. (1) In the calcium isotopic reactions, the
IYR(m) depends on the isospin or the volume of the projectile, but
$\delta_{np}$ greatly influences the nonlinear part of the IYR(m). The IYR(m)
does not depend on the colliding source in reactions of small $b_{\mbox{max}}$
for the nonneutron-rich projectiles, and does not depend on the collision
sources in reactions by the neutron-rich projectiles; (2) In reactions of the
$A = 45$ isobars, though IYR(m) depends on the isospin of projectile, IYR(m)
shows small dependence on isospin if $\delta_{np} > 0$; (3) In the reactions of
projectiles having similar $\delta_{np}$, the IYR(m) in the small mass
fragments show no dependence on the volume and the isospin of the projectile
when the mass of the projectile is relatively large. Specially, the dependence
of IYR(m) on the mass of the isospin of the projectile vanishes when
$\delta_{np}\sim0.02$fm. \item[Conclusions] The linear and nonlinear parts of
the IYR(m) are governed by the core and the surface (skin) of the projectile,
respectively. The neutron-skin effects can well explain the systematic
dependence of the IYR(m).


title: Implications of local parity breaking in heavy ion collisions

abstract:
  Recent data on dilepton production in heavy ion collisions revealed an
abnormal excess in the region of invariant masses below 1 GeV. Our proposal is
the creation of a slowly varying time-dependent pseudoscalar condensate within
the hot nuclear fireball that comes from the very collision. The local parity
breaking effect that immediately arises substantially modifies the vector meson
properties leading to an excess of lepton pairs that could be a part of the
explanation for the observed abnormal dilepton yield.


title:
Adoption of bundled services with network externalities and correlated
  affinities

abstract:
  The goal of this paper is to develop a principled understanding of when it is
beneficial to bundle technologies or services whose value is heavily dependent
on the size of their user base, i.e., exhibits positive exernalities. Of
interest is how the joint distribution, and in particular the correlation, of
the values users assign to components of a bundle affect its odds of success.
The results offer insight and guidelines for deciding when bundling new
Internet technologies or services can help improve their overall adoption. In
particular, successful outcomes appear to require a minimum level of value
correlation.


title:
Quantum diffusion due to scattering non-locality in nanoscale
  semiconductors

abstract:
  In view of its local character, the semiclassical or Boltzmann theory is
intrinsically unable to describe transport phenomena on ultrashort space and
time scales, and to this purpose genuine quantum-transport approaches are
imperative. By employing a density-matrix simulation strategy recently
proposed, we shall demonstrate its power and flexibility in describing
quantum-diffusion phenomena in nanoscale semiconductors. In particular, as for
the case of carrier-carrier relaxation in photoexcited semiconductors, our
analysis will show the failure of simplified dephasing models in describing
phonon-induced scattering non-locality, pointing out that such limitation is
particularly severe for the case of quasielastic dissipation processes.


title: A Tauberian theorem for strong Feller semigroups

abstract:
  We prove that a weakly ergodic, eventually strong Feller semigroup on the
space of measures on a Polish space converges strongly to a projection onto its
fixed space.


title: Rozansky-Witten-type invariants from symplectic Lie pairs

abstract:
  We introduce symplectic structures on "Lie pairs" of (real or complex)
algebroids as studied by Chen, Stienon and the second author (From Atiyah
classes to homotopy Leibniz algebras, arXiv:1204.1075), encompassing
homogeneous symplectic spaces, symplectic manifolds with a $\mathfrak g$-action
and holomorphic symplectic manifolds. We show that to each such symplectic Lie
pair are associated Rozansky-Witten-type invariants of three-manifolds and
knots, given respectively by weight systems on trivalent and chord diagrams.


title:
Natural orbitals in relation to quantum information theory: from model
  light atoms through to emergent metallic properties

abstract:
  The review begins with a consideration of 3 forms of quantum information
entropy associated with Shannon and Jaynes. For model two-electron spin
compensated systems, some analytic progress is first reported. The Jaynes
entropy is clearly related to correlation kinetic energy. A way of testing the
usefulness of a known uncertainty principle inequality is proposed for a whole
class of model two-electron atoms with harmonic confinement but variable
electron-electron interaction. Emerging properties are then studied by
reference to bcc Na at ambient pressure and its modeling by `jellium'. Jellium
itself has collective behaviour with changes of the density, especially
noteworthy being the discontinuity of the momentum distribution at the Fermi
surface. This has almost reduced to zero at $r_s = 100$ a.u., the neighbourhood
in which the quantal Wigner electron solid transition is known to occur.
However, various workers have studied crystalline Na under pressure and their
results are compared and contrasted. Work by DFT on K, Rb, and Cs is discussed,
but now with reduced density from the ambient pressure value. The crystalline
results for the cohesive energy of these metals as a function of lattice
parameters and local coordination number are shown to be closely reproduced by
means of ground and excited states for dimer potential energy curves. Then,
pair potentials for liquid Na and Be are reviewed, and compared with the
results of computer simulations from the experimental structure factor for Na.
Finally, magnetic field effects are discussed. First a phenomenological model
of the metal-to-insulator transition is presented with an order parameter which
is the discontinuity in the Fermi momentum distribution. Lastly, experiments on
a two-dimensional electron assembly in a GaAs/AlGaAs heterojunction in a
perpendicular magnetic field are briefly reviewed and then interpreted.


title: An effective theory for QCD with an axial chemical potential

abstract:
  We consider the low energy realization of QCD in terms of meson fields when
an axial chemical potential is present; a situation that may be relevant in
heavy ion collisions. We shall demonstrate that the presence of an axial charge
constitutes an explicit source of parity breaking. The eigenstates of strong
interactions do not have a definite parity and interactions that would
otherwise be forbidden compete with the familiar ones. In this work, we first
focus on scalars and pseudoscalars that are described by a generalized linear
sigma model; and next, we give some hints on how the Vector Meson Dominance
model describes the vector sector.


title: Regularity of minimizers of autonomous convex variational integrals

abstract:
  We establish local higher integrability and differentiability results for
minimizers of variational integrals $$ \mathfrak{F}(v,\Omega) = \int_{\Omega}
/! F(Dv(x)) \, dx $$ over $W^{1,p}$--Sobolev mappings $u \colon \Omega \subset
{\mathbb R}^n \to {\mathbb R}^N$ satisfying a Dirichlet boundary condition. The
integrands $F$ are assumed to be autonomous, convex and of $(p,q)$ growth, but
are otherwise not subjected to any further structure conditions, and we
consider exponents in the range $1<p \leq q < p^{\ast}$, where $p^{\ast}$
denotes the Sobolev conjugate exponent of $p$.


title: Galois subfields of tame division algebras

abstract:
  We show that a finite-dimensional tame division algebra D over a Henselian
field F has a maximal subfield Galois over F if and only if its residue
division algebra has a maximal subfield Galois over the residue field of F.
  This generalizes the mechanism behind several known noncrossed product
constructions to a crossed product criterion for all tame division algebras,
and in particular for all division algebras if the residue characteristic is 0.
If the residue field is a global field, the criterion leads to a description of
the location of noncrossed products among tame division algebras, and their
discovery in new parts of the Brauer group.


title:
Measurement of a reaction-diffusion crossover in exciton-exciton
  recombination inside carbon nanotubes using femtosecond optical absorption

abstract:
  Exciton-exciton recombination in isolated semiconducting single-walled carbon
nanotubes was studied using femtosecond transient absorption. Under sufficient
excitation to saturate the optical absorption, we observed an abrupt transition
between reaction- and diffusion- limited kinetics, arising from reactions
between incoherent localized excitons with a finite probability of ~ 0.2 per
encounter. This represents the first experimental observation of a crossover
between classical and critical kinetics in a 1D coalescing random walk, which
is a paradigm for the study of non- equilibrium systems.


title: Unbounded order convergence in dual spaces

abstract:
  A net $(x_\alpha)$ in a vector lattice $X$ is said to be {unbounded order
convergent} (or uo-convergent, for short) to $x\in X$ if the net
$(\abs{x_\alpha-x}\wedge y)$ converges to 0 in order for all $y\in X_+$. In
this paper, we study unbounded order convergence in dual spaces of Banach
lattices. Let $X$ be a Banach lattice. We prove that every norm bounded
uo-convergent net in $X^*$ is $w^*$-convergent iff $X$ has order continuous
norm, and that every $w^*$-convergent net in $X^*$ is uo-convergent iff $X$ is
atomic with order continuous norm. We also characterize among $\sigma$-order
complete Banach lattices the spaces in whose dual space every simultaneously
uo- and $w^*$-convergent sequence converges weakly/in norm.


title:
The magnetospheric accretion/ejection process in young stellar objects:
  open issues and perspectives

abstract:
  This summary talk aims at highlighting some of the remaining open issues
regarding the physics of the magnetospheric accretion/ejection process in young
stellar objects (YSOs). It lists a number of questions related to YSOs magnetic
fields and accretion regimes, the structure and properties of accretion shocks,
the origin of multiple outflow components, and the impact of the star-disk
magnetic interaction onto early angular momentum evolution.


title: On the Steinberg character of an orthogonal group over a finite field

abstract:
  We determine the irreducible constituents of the Steinberg character of an
orthogonal group over a finite field restricted to the orthogonal group of one
less dimension


title: Geometric phase shifts in biological oscillators

abstract:
  Many intracellular processes continue to oscillate during the cell cycle.
Although it is not well-understood how they are affected by discontinuities in
the cellular environment, the general assumption is that oscillations remain
robust provided the period of cell divisions is much larger than the period of
the oscillator. Here, I will show that under these conditions a cell will in
fact have to correct for an additional quantity added to the phase of
oscillation upon every repetition of the cell cycle. The resulting phase shift
is an analogue of the geometric phase, a curious entity first discovered in
quantum mechanics. In this Letter, I will discuss the theory of the geometric
phase shift and demonstrate its relevance to biological oscillations.


title: Domain wall motion in magnetic nanowires: An asymptotic approach

abstract:
  We develop a systematic asymptotic description for domain wall motion in
one-dimensional magnetic nanowires under the influence of small applied
magnetic fields and currents and small material anisotropy. The magnetization
dynamics, as governed by the Landau--Lifshitz--Gilbert equation, is
investigated via a perturbation expansion. We compute leading-order behaviour,
propagation velocities, and first-order corrections of both travelling waves
and oscillatory solutions, and find bifurcations between these two types of
solutions. This treatment provides a sound mathematical foundation for numerous
results in the literature obtained through more ad hoc arguments.

categories: cond-mat.mtrl-sci math-ph math.AP math.MP


title:
Extracting Mass Hierarchy Information from Simple Analysis of Neutrino
  Mass Splitting

abstract:
  Based on the independent measurements on neutrino mass splitting $|\Delta
m^2_{\mu\mu}|$, $|\Delta m^2_{ee}|$, $\Delta m^2_{21}$, and recent measurements
by the T2K Collaboration, we carry out a simple fitting analysis on $\Delta
m^2_{32}$ and $\Delta m^2_{31}$ in normal hierarchy and inverse hierarchy
respectively, suggesting $\Delta
m^2_{32}=(2.46\pm0.07)\times10^{-3}~\mbox{eV}^2$ and $\Delta
m^2_{31}=(2.53\pm0.07)\times10^{-3}~\mbox{eV}^2$ in normal hierarchy, or
$\Delta m^2_{32}$=$-(2.51\pm0.07)\times10^{-3}~\mbox{eV}^2$ and $\Delta
m^2_{31}$=$-(2.44\pm0.07)\times10^{-3}~\mbox{eV}^2$ in invert hierarchy. The
simple analysis indicate that both normal and inverted hierarchy are consistent
with current experimental measurements on mass splitting. The p-value for
normal hierarchy and that for inverted hierarchy are 62% and 55%, respectively.
This reveals a slight favor for the normal hierarchy. It is suggested that
further measurements on the mass splitting with higher accuracy are necessary
to determine the neutrino mass hierarchy.


title:
A structural analysis on Gravity of Trade: on removing distance from the
  model

abstract:
  The Gravity Model is the workhorse for empirical studies in International
Economies for its empirical power and it is commonly used in explaining the
trade flow between countries; it relies on a function that relates the trade
with the masses of the two countries and the distance (as a proxy of the
trasport costs) between them. However, the notion that using of distance
functions in conventional interaction models effectively captures spatial
dependence in international flows has long been challenged. It has been
recently fully recognized that a spatial interaction effect exists essentially
due to the spatial spillover and the third country effect. This motivates the
introduction of the spatial autoregressive components in the so-called spatial
gravity model of trade. A so-called weight matrix is used in order to define
the set of the spatial neighbors and it is traditionally based on the inverse
of the distance. Two issues follow from this standard procedure: the first
regards the biasness of the distance if it is used as a proxy of the transport
costs in a panel data, the second is related to the collinearity emerging if we
use distance twice. So, several attempt were made in the recent literature
having the scope of remove the distance. We propose a theoretically consistent
procedure based on Anderson, Van Wincoop derivation model, and some ad-hoc
tests, relating to this attempt. The empirical results based on a 22-years
panel of OECD countries are conforting, and they allow us to estimate the model
without the distance, if properly replaced by a set of fixed effects. This
article, in addition, fits in the dispute about how to estimate the
multilateral resistance terms.


title: Multi-loop Integrand Reduction with Computational Algebraic Geometry

abstract:
  We discuss recent progress in multi-loop integrand reduction methods.
Motivated by the possibility of an automated construction of multi-loop
amplitudes via generalized unitarity cuts we describe a procedure to obtain a
general parameterisation of any multi-loop integrand in a renormalizable gauge
theory. The method relies on computational algebraic geometry techniques such
as Gr\"obner bases and primary decomposition of ideals. We present some results
for two and three loop amplitudes obtained with the help of the Macaulay2
computer algebra system and the Mathematica package BasisDet.


title:
Slowly fading super-luminous supernovae that are not pair-instability
  explosions

abstract:
  Super-luminous supernovae that radiate more than 10^44 ergs per second at
their peak luminosity have recently been discovered in faint galaxies at
redshifts of 0.1-4. Some evolve slowly, resembling models of 'pair-instability'
supernovae. Such models involve stars with original masses 140-260 times that
of the Sun that now have carbon-oxygen cores of 65-30 solar masses. In these
stars, the photons that prevent gravitational collapse are converted to
electron-positron pairs, causing rapid contraction and thermonuclear
explosions. Many solar masses of 56Ni are synthesized; this isotope decays to
56Fe via 56Co, powering bright light curves. Such massive progenitors are
expected to have formed from metal-poor gas in the early Universe. Recently,
supernova 2007bi in a galaxy at redshift 0.127 (about 12 billion years after
the Big Bang) with a metallicity one-third that of the Sun was observed to look
like a fading pair-instability supernova. Here we report observations of two
slow-to-fade super-luminous supernovae that show relatively fast rise times and
blue colours, which are incompatible with pair-instability models. Their
late-time light-curve and spectral similarities to supernova 2007bi call the
nature of that event into question. Our early spectra closely resemble typical
fast-declining super-luminous supernovae, which are not powered by
radioactivity. Modelling our observations with 10-16 solar masses of
magnetar-energized ejecta demonstrates the possibility of a common explosion
mechanism. The lack of unambiguous nearby pair-instability events suggests that
their local rate of occurrence is less than 6x10^-6 times that of the
core-collapse rate.


title: Time series, correlation matrices and random matrix models

abstract:
  In this set of five lectures the authors have presented techniques to analyze
open classical and quantum systems using correlation matrices. For diverse
reasons we shall see that random matrices play an important role to describe a
null hypothesis or a minimum information hypothesis for the description of a
quantum system or subsystem. In the former case various forms of correlation
matrices of time series associated with the classical observables of some
system. The fact that such series are necessarily finite, inevitably introduces
noise and this finite time influence lead to a random or stochastic component
in these time series. By consequence random correlation matrices have a random
component, and corresponding ensembles are used. In the latter we use random
matrices to describe high temperature environment or uncontrolled
perturbations, ensembles of differing chaotic systems etc.


title: On the supersingular locus of the GU(2,2) Shimura variety

abstract:
  We describe the supersingular locus of a GU(2,2) Shimura variety at a prime
inert in the corresponding quadratic imaginary field.


title: Self-force on an electric dipole in the spacetime of a cosmic string

abstract:
  We calculate the electrostatic self-force on an electric dipole in the
spacetime generated by a static, thin, infinite and straight cosmic string. The
electric dipole is held fixed in different configurations, namely, parallel,
perpendicular to the cosmic string and oriented along the azimuthal direction
around this topological defect, which is stretched along the z axis. We show
that the self-force is equivalent to an interaction of the electric dipole with
an effective dipole moment which depends on the linear mass density of the
cosmic string and on the configuration. The plots of the self-forces as
functions of the parameter which determines the angular deficit of the cosmic
string are shown for those different configurations.


title: Parameter invariant Lagrangian formulation of Kawaguchi geometry

abstract:
  This Ph.D. thesis is devoted to the constructions of Lagrangian formulation
on Finsler and Kawaguchi manifolds. While Finsler geometry is a natural
extension of Riemannian geometry, Kawaguchi geometry is the extension of
Finsler geometry to higher order derivatives and to k-dimensional parameter
space. The latter extension is also called areal geometry in some references.
On Finsler (Kawaguchi) manifold, we can define a reparameterisation invariant 1
(k)-dimensional area by the Hilbert (Kawaguchi) form, which we take as an
action. The equation of motion obtained from such action also has the property
of reparameterisation invariance. In this framework, the solution manifold of
the Euler-Lagrange equation is realised as a submanifold of Finsler/Kawaguchi
manifold, and no fibered structure over the parameter space is needed. We also
show that for the case of first order k-dimensional parameter space and second
order 1-dimensional parameter space, a global Lagrangian could be constructed.
For second order k-dimensional parameter space, Lagrangian is not global but it
still has the reparameterisation invariant property. Such theory is expected to
provide the ideal stage for formulating fundamental theories of physics,
especially for cases such as when one needs to consider the mixing of spacetime
and field variables. It is shown that locally, any conventional Lagrangian
could be reformulated by the parameter independent Lagrangian. Furthermore, the
parameter independent property will gives us the freedom of choosing a
parameter, which in some cases turns out to be useful in finding solutions and
symmetries.


title: Quantum billiards in multidimensional models with branes

abstract:
  Gravitational D-dimensional model with l scalar fields and several forms is
considered. When cosmological type diagonal metric is chosen, an
electromagnetic composite brane ansatz is adopted and certain restrictions on
the branes are imposed the conformally covariant Wheeler-DeWitt (WDW) equation
for the model is studied. Under certain restrictions asymptotic solutions to
WDW equation are found in the limit of the formation of the billiard walls
which reduce the problem to the so-called quantum billiard on the (D+ l
-2)-dimensional Lobachevsky space. Two examples of quantum billiards are
considered. The first one deals with 9-dimensional quantum billiard for D = 11
model with 330 four-forms which mimic space-like M2- and M5-branes of D=11
supergravity. The second one deals with the 9-dimensional quantum billiard for
D =10 gravitational model with one scalar field, 210 four-forms and 120
three-forms which mimic space-like D2-, D4-, FS1- and NS5-branes in D = 10 II A
supergravity. It is shown that in both examples wave functions vanish in the
limit of the formation of the billiard walls (i.e. we get a quantum resolution
of the singularity for 11D model) but magnetic branes could not be neglected in
calculations of quantum asymptotic solutions while they are irrelevant for
classical oscillating behaviour when all 120 electric branes are present.


title: Continuous discretization of infinite dimensional Hilbert spaces

abstract:
  In quantum theory, observables with a continuous spectrum are known to be
fundamentally different from those with a discrete and finite spectrum. While
some fundamental tests and applications of quantum mechanics originally
formulated for discrete variables have been translated to continuous ones, this
is not the case in general. For instance, despite their importance, no
experimental demonstration of nonlocality exists in the continuous variables
regime. Attempts to bridge this gap and put continuous variables on a closer
footing to discrete ones used dichotomization. However, this approach considers
only discrete properties of the continuum, and its infinitesimal properties are
not fully exploited. Here we show that it is possible to manipulate, detect and
classify continuous variable states using observables with a continuous
spectrum revealing properties and symmetries which are analogous to finite
discrete systems. Our approach leads to an operational way to define and adapt,
to arbitrary continuous quantum systems, quantum protocols and algorithms
typical to discrete systems.


title: Generalized monotone operators on dense sets

abstract:
  In the present work we show that the local generalized monotonicity of a
lower semicontinuous set-valued operator on some certain type of dense sets
ensures the global generalized monotonicity of that operator. We achieve this
goal gradually by showing at first that the lower semicontinuous set-valued
functions of one real variable, which are locally generalized monotone on a
dense subsets of their domain are globally generalized monotone. Then, these
results are extended to the case of set-valued operators on arbitrary Banach
spaces. We close this work with a section on the global generalized convexity
of a real valued function, which is obtained out of its local counterpart on
some dense sets.


title: On cluster algebras from once punctured closed surfaces

abstract:
  We show that many cluster-theoretic properties of the Markov quiver hold also
for adjacency quivers of triangulations of once-punctured closed surfaces of
arbitrary genus.
  Along the way we consider the class P of quivers introduced by Kontsevich and
Soibelman, characterize the mutation-finite quivers that belong to that class
and draw some conclusions regarding non-degenerate potentials on them.


title:
Current status of constraints on the elements of the neutrino mass
  matrix

abstract:
  We analyse the mass matrix of the three light neutrinos in the basis where
the charged-lepton mass matrix is diagonal and discuss constraints on its
elements for the Majorana and the Dirac case.


title:
Inference, Sampling, and Learning in Copula Cumulative Distribution
  Networks

abstract:
  The cumulative distribution network (CDN) is a recently developed class of
probabilistic graphical models (PGMs) permitting a copula factorization, in
which the CDF, rather than the density, is factored. Despite there being much
recent interest within the machine learning community about copula
representations, there has been scarce research into the CDN, its amalgamation
with copula theory, and no evaluation of its performance. Algorithms for
inference, sampling, and learning in these models are underdeveloped compared
those of other PGMs, hindering widerspread use.
  One advantage of the CDN is that it allows the factors to be parameterized as
copulae, combining the benefits of graphical models with those of copula
theory. In brief, the use of a copula parameterization enables greater
modelling flexibility by separating representation of the marginals from the
dependence structure, permitting more efficient and robust learning. Another
advantage is that the CDN permits the representation of implicit latent
variables, whose parameterization and connectivity are not required to be
specified. Unfortunately, that the model can encode only latent relationships
between variables severely limits its utility.
  In this thesis, we present inference, learning, and sampling for CDNs, and
further the state-of-the-art. First, we explain the basics of copula theory and
the representation of copula CDNs. Then, we discuss inference in the models,
and develop the first sampling algorithm. We explain standard learning methods,
propose an algorithm for learning from data missing completely at random
(MCAR), and develop a novel algorithm for learning models of arbitrary
treewidth and size. Properties of the models and algorithms are investigated
through Monte Carlo simulations. We conclude with further discussion of the
advantages and limitations of CDNs, and suggest future work.


title: Maximum percolation time in two-dimensional bootstrap percolation

abstract:
  We consider a classic model known as bootstrap percolation on the $n \times
n$ square grid. To each vertex of the grid we assign an initial state, infected
or healthy, and then in consecutive rounds we infect every healthy vertex that
has at least $2$ already infected neighbours. We say that percolation occurs if
the whole grid is eventually infected. In this paper, contributing to a recent
series of extremal results in this field, we prove that the maximum time a
bootstrap percolation process can take to eventually infect the entire vertex
set of the grid is $13n^2/18+O(n)$.


title: The theory of vector-modular forms for the modular group

abstract:
  We explain the basic ideas, describe with proofs the main results, and
demonstrate the effectiveness, of an evolving theory of vector-valued modular
forms (vvmf). To keep the exposition concrete, we restrict here to the special
case of the modular group. Among other things,we construct vvmf for arbitrary
multipliers, solve the Mittag-Leffler problem here, establish Serre duality and
find a dimension formula for holomorphic vvmf, all in far greater generality
than has been done elsewhere. More important, the new ideas involved are
sufficiently simple and robust that this entire theory extends directly to any
genus-0 Fuchsian group.


title: Matching LBO eigenspace of non-rigid shapes via high order statistics

abstract:
  A fundamental tool in shape analysis is the virtual embedding of the
Riemannian manifold describing the geometry of a shape into Euclidean space.
Several methods have been proposed to embed isometric shapes in flat domains
while preserving distances measured on the manifold. Recently, attention has
been given to embedding shapes into the eigenspace of the Lapalce-Beltrami
operator. The Laplace-Beltrami eigenspace preserves the diffusion distance, and
is invariant under isometric transformations. However, Laplace-Beltrami
eigenfunctions computed independently for different shapes are often
incompatible with each other. Applications involving multiple shapes, such as
pointwise correspondence, would greatly benefit if their respective
eigenfunctions were somehow matched. Here, we introduce a statistical approach
for matching eigenfunctions. We consider the values of the eigenfunctions over
the manifold as sampling of random variables, and try to match their
multivariate distributions. Comparing distributions is done indirectly, using
high order statistics. We show that the permutation and sign ambiguities of low
order eigenfunctions, can be inferred by minimizing the difference of their
third order moments. The sign ambiguities of antisymmetric eigenfunctions can
be resolved by exploiting isometric invariant relations between the gradients
of the eigenfunctions and the surface normal. We present experiments
demonstrating the success of the proposed method applied to feature point
correspondence.


title: On non-abelian Schur groups

abstract:
  A finite group G is called Schur, if every Schur ring over G is associated in
a natural way with a regular subgroup of Sym(G) that is isomorphic to G. We
prove that any nonabelian Schur group G is metabelian and the number of
distinct prime divisors of the order of G does not exceed 7.


title:
Scoring dynamics across professional team sports: tempo, balance and
  predictability

abstract:
  Despite growing interest in quantifying and modeling the scoring dynamics
within professional sports games, relative little is known about what patterns
or principles, if any, cut across different sports. Using a comprehensive data
set of scoring events in nearly a dozen consecutive seasons of college and
professional (American) football, professional hockey, and professional
basketball, we identify several common patterns in scoring dynamics. Across
these sports, scoring tempo---when scoring events occur---closely follows a
common Poisson process, with a sport-specific rate. Similarly, scoring
balance---how often a team wins an event---follows a common Bernoulli process,
with a parameter that effectively varies with the size of the lead. Combining
these processes within a generative model of gameplay, we find they both
reproduce the observed dynamics in all four sports and accurately predict game
outcomes. These results demonstrate common dynamical patterns underlying
within-game scoring dynamics across professional team sports, and suggest
specific mechanisms for driving them. We close with a brief discussion of the
implications of our results for several popular hypotheses about sports
dynamics.

categories: stat.AP cs.CY physics.data-an physics.soc-ph


title:
Diverse, massive-star-associated sources for elements heavier than Fe
  and the roles of neutrinos

abstract:
  Massive-star-associated models for production of elements heavier than Fe are
reviewed. The important roles of neutrinos in many of these models are
discussed along with uncertainties in the relevant neutrino physics. Data on
elemental abundances in metal-poor stars are presented and their constraints on
diverse sources for elements heavier than Fe are emphasized.


title:
Classical calculation of relativistic frequency-shifts in an ideal
  Penning trap

abstract:
  The ideal Penning trap consists of a uniform magnetic field and an
electrostatic quadrupole potential. In the classical low-energy limit, the
three characteristic eigenfrequencies of a charged particle trapped in this
configuration do not depend on the amplitudes of the three eigenmotions. No
matter how accurate the experimental realization of the ideal Penning trap, its
harmonicity is ultimately compromised by special relativity. Using a classical
formalism of first-order perturbation theory, we calculate the relativistic
frequency-shifts associated with the motional degrees of freedom for a spinless
particle stored in an ideal Penning trap, and we compare the results with the
simple but surprisingly accurate model of relativistic mass-increase.


title: Axionic Dark Radiation and the Milky Way's Magnetic Field

abstract:
  Recently it has been suggested that dark radiation in the form of axions
produced during the decay of string theory moduli fields could be responsible
for the soft x-ray excess in galaxy clusters. These soft X-ray photons come
about due to the conversion of these axions into photons in the magnetic fields
of the clusters. In this work we calculate the conversion of axionic dark
radiation into X-ray photons in the magnetic field of our own Galaxy. We
consider Delta N ~ 0.5 worth of dark radiation made up of axions with energy of
order 0.1-1 keV. We show that it is possible, if a little optimistic, to
explain the large regions of X-ray emission located above and below the centre
of the Galactic plane detected in the 3/4 keV ROSAT all sky map completely due
to the conversion of dark radiation into photons with an inverse axion-photon
coupling of M ~ 3e13 GeV and an axion mass of m < 1e-12 eV. Different parameter
values could explain both these features and the 3/4 keV X-ray background. More
conservatively, these X-ray observations are a good way to constrain such
models of axionic dark radiation.


title: Non-Inertial Frames in Special and General Relativity

abstract:
  There is a review of what is known about global non-inertial frames in
special and general relativity.


title:
Searching for a highly unlikely frame dependent speed of light using a
  one-way test

abstract:
  At first blush, what appears to be a purely physical question to measure any
velocity: how to measure the velocity on a one-way trip? However, due to the
debates of the clock-synchronization and the successes of Special Relativity
(SR), searching of the possibility of one-way speed of light measurement did
not receive wider attention since the declaration of the constancy of the speed
of light in vacuum by Maxwell's Electrodynamics in 1864. However, our analysis
suggests that the debates of the clock synchronization are insignificant when
one uses a one-way experiment to test the isotropy of the speed of light - the
fundamental postulate of SR. Searching of the possibility of one-way speed of
light to test SR is introduced by reviewing recent one-way tests.


title: Affine Cellularity of Khovanov-Lauda-Rouquier Algebras of Finite Types

abstract:
  We prove that the Khovanov-Lauda-Rouquier algebras $R_\alpha$ of finite type
are (graded) affine cellular in the sense of Koenig and Xi. In fact, we
establish a stronger property, namely that the affine cell ideals in $R_\alpha$
are generated by idempotents. This in particular implies the (known) result
that the global dimension of $R_\alpha$ is finite.


title:
Engineering the Quantum Anomalous Hall Effect in Graphene with Uniaxial
  Strains

abstract:
  We theoretically investigate the manipulation of the quantum anomalous Hall
effect (QAHE) in graphene by means of the uniaxial strain. The values of Chern
number and Hall conductance demonstrate that the strained graphene in presence
of Rashba spin-orbit coupling and exchange field, for vanishing intrinsic
spin-orbit coupling, possesses non-trivial topological phase which is robust
against the direction and modulus of the strain. Besides, we also find that the
interplay between Rashba and intrinsic spin-orbit couplings results in a
topological phase transition in the strained graphene. Remarkably, as the
strain strength is increased beyond approximately 7%, the critical parameters
of the exchange field for triggering the quantum anomalous Hall phase
transition show distinct behaviors - decrease (increase) for strains along
zigzag (armchair) direction. Our findings open up a new platform for
manipulation of the QAHE by an experimentally accessible strain deformation of
the graphene structure, with promising application on novel quantum electronic
devices with high energy efficiency performance.


title:
The p-cohomology of algebraic varieties and special values of zeta
  functions

abstract:
  The p-cohomology of an algebraic variety in characteristic p lies naturally
in the category $D_{c}^{b}(R)$ of coherent complexes of graded modules over the
Raynaud ring (Ekedahl-Illusie-Raynaud). We study homological algebra in this
category. When the base field is finite, our results provide relations between
the the absolute cohomology groups of algebraic varieties, log varieties,
algebraic stacks, etc. and the special values of their zeta functions. These
results provide compelling evidence that $D_{c}^{b}(R)$ is the correct target
for p-cohomology in characteristic p.


title:
Minimal length, maximal momentum and thermodynamics of black body
  radiation

abstract:
  In this paper we study thermodynamics of black body radiation in the presence
of quantum gravitational effects through a Generalized Uncertainty Principle
that admits both a minimal measurable length and a maximal momentum. We focus
on quantum gravity induced modifications of thermodynamical quantities in this
framework. Some important issues such as the generalized Planck distribution,
Wien s law and Dulong Petit law are studied in this setup with details.