title:
Factorization and N^3LL_p+NNLO Predictions for the Higgs Cross Section
  with a Jet Veto

abstract:
  We have recently derived a factorization formula for the Higgs-boson
production cross section in the presence of a jet veto, which allows for a
systematic resummation of large Sudakov logarithms of the form alpha_s^n
ln^m(p_T^veto/m_H), along with the large virtual corrections known to affect
also the total cross section. Here we determine the ingredients entering this
formula at two-loop accuracy. Specifically, we compute the dependence on the
jet-radius parameter R, which is encoded in the two-loop coefficient of the
collinear anomaly, by means of a direct, fully analytic calculation in the
framework of soft-collinear effective theory. We confirm the result obtained by
Banfi et al. from a related calculation in QCD, and demonstrate that
factorization-breaking, soft-collinear mixing effects do not arise at leading
power in p_T^veto/m_H, even for R=O(1). In addition, we extract the two-loop
collinear beam functions numerically. We present detailed numerical predictions
for the jet-veto cross section with partial next-to-next-to-next-to-leading
logarithmic accuracy, matched to the next-to-next-to-leading order cross
section in fixed-order perturbation theory. The only missing ingredients at
this level of accuracy are the three-loop anomaly coefficient and the four-loop
cusp anomalous dimension, whose numerical effects we estimate to be small.


title: Pion electromagnetic form factor at spacelike momenta

abstract:
  A novel method is employed to compute the pion electromagnetic form factor,
F_\pi(Q^2), on the entire domain of spacelike momentum transfer using the
Dyson-Schwinger equation (DSE) framework in quantum chromodynamics (QCD). The
DSE architecture unifies this prediction with that of the pion's valence-quark
parton distribution amplitude (PDA). Using this PDA, the leading-order,
leading-twist perturbative QCD result for Q^2 F_\pi(Q^2) underestimates the
full computation by just 15% on Q^2>~8GeV^2, in stark contrast with the result
obtained using the asymptotic PDA. The analysis shows that hard contributions
to the pion form factor dominate for Q^2>~8GeV^2 but, even so, the magnitude of
Q^2 F_\pi(Q^2) reflects the scale of dynamical chiral symmetry breaking, a
pivotal emergent phenomenon in the Standard Model.


title: Splittings and Ramsey Properties of Permutation Classes

abstract:
  We say that a permutation p is 'merged' from permutations q and r, if we can
color the elements of p red and blue so that the red elements are
order-isomorphic to q and the blue ones to r. A 'permutation class' is a set of
permutations closed under taking subpermutations. A permutation class C is
'splittable' if it has two proper subclasses A and B such that every element of
C can be obtained by merging an element of A with an element of B.
  Several recent papers use splittability as a tool in deriving enumerative
results for specific permutation classes. The goal of this paper is to study
splittability systematically. As our main results, we show that if q is a
sum-decomposable permutation of order at least four, then the class Av(q) of
all q-avoiding permutations is splittable, while if q is a simple permutation,
then Av(q) is unsplittable.
  We also show that there is a close connection between splittings of certain
permutation classes and colorings of circle graphs of bounded clique size.
Indeed, our splittability results can be interpreted as a generalization of a
theorem of Gy\'arf\'as stating that circle graphs of bounded clique size have
bounded chromatic number.


title:
Existence and conditional energetic stability of solitary
  gravity-capillary water waves with constant vorticity

abstract:
  We present an existence and stability theory for gravity-capillary solitary
waves with constant vorticity on the surface of a body of water of finite
depth. Exploiting a rotational version of the classical variational principle,
we prove the existence of a minimiser of the wave energy $\mathcal H$ subject
to the constraint $\mathcal I=2\mu$, where $\mathcal I$ is the wave momentum
and $0< \mu \ll 1$. Since $\mathcal H$ and $\mathcal I$ are both conserved
quantities a standard argument asserts the stability of the set $D_\mu$ of
minimisers: solutions starting near $D_\mu$ remain close to $D_\mu$ in a
suitably defined energy space over their interval of existence.
  In the applied mathematics literature solitary water waves of the present
kind are described by solutions of a Korteweg-deVries equation (for strong
surface tension) or a nonlinear Schr\"{o}dinger equation (for weak surface
tension). We show that the waves detected by our variational method converge
(after an appropriate rescaling) to solutions of the appropriate model equation
as $\mu \downarrow 0$


title:
Fractal and Mathematical Morphology in Intricate Comparison between
  Tertiary Protein Structures

abstract:
  Intricate comparison between two given tertiary structures of proteins is as
important as the comparison of their functions. Several algorithms have been
devised to compute the similarity and dissimilarity among protein structures.
But, these algorithms compare protein structures by structural alignment of the
protein backbones which are usually unable to determine precise differences. In
this paper, an attempt has been made to compute the similarities and
dissimilarities among 3D protein structures using the fundamental mathematical
morphology operations and fractal geometry which can resolve the problem of
real differences. In doing so, two techniques are being used here in
determining the superficial structural (global similarity) and local similarity
in atomic level of the protein molecules. This intricate structural difference
would provide insight to Biologists to understand the protein structures and
their functions more precisely.


title: Capturing self-propelled particles in a moving microwedge

abstract:
  Catching fish with a fishing net is typically done either by dragging a
fishing net through quiescent water or by placing a stationary basket trap into
a stream. We transfer these general concepts to micron-sized self-motile
particles moving in a solvent at low Reynolds number and study their collective
trapping behaviour by means of computer simulations of a two-dimensional system
of self-propelled rods. A chevron-shaped obstacle is dragged through the active
suspension with a constant speed $v$ and acts as a trapping "net". Three
trapping states can be identified corresponding to no trapping, partial
trapping and complete trapping and their relative stability is studied as a
function of the apex angle of the wedge, the swimmer density and the drag speed
$v$. When the net is dragged along the inner wedge, complete trapping is
facilitated and a partially trapped state changes into a complete trapping
state if the drag speed exceeds a certain value. Reversing the drag direction
leads to a reentrant transition from no trapping, complete trapping, back to no
trapping upon increasing the drag speed along the outer wedge contour. The
transition to complete trapping is marked by a templated self-assembly of rods
forming polar smectic structures anchored onto the inner contour of the wedge.
Our predictions can be verified in experiments of artificial or microbial
swimmers confined in microfluidic trapping devices.


title: On the Hyperbolicity of Large-Scale Networks

abstract:
  Through detailed analysis of scores of publicly available data sets
corresponding to a wide range of large-scale networks, from communication and
road networks to various forms of social networks, we explore a little-studied
geometric characteristic of real-life networks, namely their hyperbolicity. In
smooth geometry, hyperbolicity captures the notion of negative curvature;
within the more abstract context of metric spaces, it can be generalized as
d-hyperbolicity. This generalized definition can be applied to graphs, which we
explore in this report. We provide strong evidence that communication and
social networks exhibit this fundamental property, and through extensive
computations we quantify the degree of hyperbolicity of each network in
comparison to its diameter. By contrast, and as evidence of the validity of the
methodology, applying the same methods to the road networks shows that they are
not hyperbolic, which is as expected. Finally, we present practical
computational means for detection of hyperbolicity and show how the test itself
may be scaled to much larger graphs than those we examined via renormalization
group methodology. Using well-understood mechanisms, we provide evidence
through synthetically generated graphs that hyperbolicity is preserved and
indeed amplified by renormalization. This allows us to detect hyperbolicity in
large networks efficiently, through much smaller renormalized versions. These
observations indicate that d-hyperbolicity is a common feature of large-scale
networks. We propose that d-hyperbolicity in conjunction with other local
characteristics of networks, such as the degree distribution and clustering
coefficients, provide a more complete unifying picture of networks, and helps
classify in a parsimonious way what is otherwise a bewildering and complex
array of features and characteristics specific to each natural and man-made
network.


title: Memory Limited, Streaming PCA

abstract:
  We consider streaming, one-pass principal component analysis (PCA), in the
high-dimensional regime, with limited memory. Here, $p$-dimensional samples are
presented sequentially, and the goal is to produce the $k$-dimensional subspace
that best approximates these points. Standard algorithms require $O(p^2)$
memory; meanwhile no algorithm can do better than $O(kp)$ memory, since this is
what the output itself requires. Memory (or storage) complexity is most
meaningful when understood in the context of computational and sample
complexity. Sample complexity for high-dimensional PCA is typically studied in
the setting of the {\em spiked covariance model}, where $p$-dimensional points
are generated from a population covariance equal to the identity (white noise)
plus a low-dimensional perturbation (the spike) which is the signal to be
recovered. It is now well-understood that the spike can be recovered when the
number of samples, $n$, scales proportionally with the dimension, $p$. Yet, all
algorithms that provably achieve this, have memory complexity $O(p^2)$.
Meanwhile, algorithms with memory-complexity $O(kp)$ do not have provable
bounds on sample complexity comparable to $p$. We present an algorithm that
achieves both: it uses $O(kp)$ memory (meaning storage of any kind) and is able
to compute the $k$-dimensional spike with $O(p \log p)$ sample-complexity --
the first algorithm of its kind. While our theoretical analysis focuses on the
spiked covariance model, our simulations show that our algorithm is successful
on much more general models for the data.


title: A remark on constrained von Karman theories

abstract:
  We derive the Euler-Lagrange equation corresponding to a variant of
non-Euclidean constrained von Karman theories.

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


title:
Ba\~{n}ados-Silk-West effect with nongeodesic particles: extremal
  horizons

abstract:
  The Ba\~{n}ados-Silk-West (BSW) effect consists in the possibility to obtain
arbitrarily large energy $E_{c.m.}$ in the centre of mass frame of two
colliding particles near the black hole horizon. One of the common beliefs was
that the action of force on these particles (say, due to gravitational
radiation) should necessarily restrict the growth of $E_{c.m.}$. We consider
extremal horizons and develop a model-independent approach and analyze the
conditions for the force to preserve or kill the effect, using the frames
attached both to observers orbiting the black hole and to ones crossing the
horizon. We argue that the aforementioned expectations are not confirmed. Under
rather general assumptions, the BSW effect survives. For equatorial motion it
is only required that in the proper frame the radial component of the force be
finite, while the azimuthal one tend to zero not too slowly. If the latter
condition is violated, we evaluate $E_{c.m.}$, which becomes indeed restricted
but remains very large for small forces.


title:
Centromere reference models for human chromosomes X and Y satellite
  arrays

abstract:
  The human genome remains incomplete, with multi-megabase sized gaps
representing the endogenous centromeres and other heterochromatic regions.
These regions are commonly enriched with long arrays of near-identical tandem
repeats, known as satellite DNAs, that offer a limited number of variant sites
to differentiate individual repeat copies across millions of bases. This
substantial sequence homogeneity challenges available assembly strategies, and
as a result, centromeric regions are omitted from ongoing genomic studies. To
address this problem, we present a locally ordered assembly across two haploid
human satellite arrays on chromosomes X and Y, resulting in an initial linear
representation of 3.83 Mb of centromeric DNA within an individual genome. To
further expand the utility of each centromeric reference sequence, we evaluate
sites within the arrays for short-read mappability and chromosome specificity.
As satellite DNAs evolve in a concerted manner, we use these centromeric
assemblies to assess the extent of sequence variation among 372 individuals
from distinct human populations. In doing so, we identify two ancient satellite
array variants in both X and Y centromeres as determined by array length and
sequence composition. This study provides an initial linear representation and
comprehensive sequence characterization of a regional centromere and
establishes a foundation to extend genomic characterization to these sites as
well as to other repeat-rich regions within complex genomes.


title:
Increasing Compression Ratio in PNG Images by k-Modulus Method for Image
  Transformation

abstract:
  Image compression is an important filed in image processing. The science
welcomes any tinny contribution that may increase the compression ratio by
whichever insignificant percentage. Therefore, the essential contribution in
this paper is to increase the compression ratio for the well known Portable
Network Graphics (PNG) image file format. The contribution starts with
converting the original PNG image into k-Modulus Method (k-MM). Practically,
taking k equals to ten, and then the pixels in the constructed image will be
integers divisible by ten. Since PNG uses Lempel-Ziv compression algorithm,
then the ability to reduce file size will increase according to the repetition
in pixels in each k-by-k window according to the transformation done by k-MM.
Experimental results show that the proposed technique (k-PNG) produces high
compression ratio with smaller file size in comparison to the original PNG
file.


title: Fragility of superposition states evaluated by the Loschmidt Echo

abstract:
  We consider the degradation of the dynamics of a Gaussian wave packet in a
harmonic oscillator under the presence of an environment. This last is given by
a single non-degenerate two level system. We analyze how the binary degree of
freedom perturbs the free evolution of the wave packet producing decoherence,
which is quantified by the Loschmidt Echo. This magnitude measures the
reversibility of a perturbed quantum evolution. In particular, we use it here
to study the relative "fragility" of coherent superpositions (cat states) with
respect to incoherent ones. This fragility or sensitivity turns to increase
exponentially with the energy separation of the two components of the
superposition.


title: Black hole bombs and explosions: from astrophysics to particle physics

abstract:
  Black holes are the elementary particles of gravity, the final state of
sufficiently massive stars and of energetic collisions. With a forty-year long
history, black hole physics is a fully-blossomed field which promises to
embrace several branches of theoretical physics. Here I review the main
developments in highly dynamical black holes with an emphasis on high energy
black hole collisions and probes of particle physics via superradiance. This
write-up, rather than being a collection of well known results, is intended to
highlight open issues and the most intriguing results.


title: Gauge theory of Kaluza-Klein and winding modes

abstract:
  We perform a Kaluza-Klein inspired rewriting of double field theory by
splitting the coordinates into `compact' and `non-compact' directions. There is
no truncation of the compact coordinates or their duals, and so this
formulation is manifestly O(d,d) invariant, with d the number of compact
directions. The action can serve as starting point for arbitrary Kaluza-Klein
ansaetze. For a torus background the theory describes the full tower of
Kaluza-Klein modes or, in the dual frame, of the winding modes. The
Kaluza-Klein vector is a gauge field for the duality-covariantized Courant
bracket algebra rather than a Lie algebra. Gauge covariance requires the
inclusion of the 2-form gauge potential descending from the Kalb-Ramond field,
leading to a structure resembling the tensor hierarchy of gauged supergravity.


title: Asymptotic Density and Computably Enumerable Sets

abstract:
  We study connections between classical asymptotic density and c.e. sets. We
prove that a c.e. Turing degree d is not low if and only if d contains a c.e.
set A of density 1 which has no computable subsets of density 1, giving a
natural characterization of non-low c.e. degrees. In contrast, we prove that
every nonzero c.e. degree contains a set which is generically computable but
not coarsely computable. There is a very close connection between the
computational complexity of a set and the computational complexity of its
density as a real number where we measure complexity of real numbers as the
position of their left Dedekind cuts in the Arithmetic Hierarchy. We
characterize the lower densities, upper densities and densities of both
computable and computably enumerable sets. We also study "computable at density
r" where r is an arbitrary real number in the unit interval. Finally, we study
connections between density and classical smallness notions such as immunity
and cohesiveness.


title: Galactic Archaeology. The dwarfs that survived and perished

abstract:
  From the archaeological point of view, the local dwarf galaxies are unique
objects in which the imprint of the conditions that shaped the early structure
formation can be studied today at high resolution. Over the last decade, this
new window into the high redshift Universe has started to be exploited using
deep wide-field imaging, high resolution spectroscopy and cutting edge N-body
and hydro-dynamical simulations. We review the recent advances in the
observational studies of the Milky Way dwarf galaxies, with the aim to
understand the properties of the population as a whole and to assist an
objective comparison between the models and the data.


title: Imprint of transition metal d-orbitals on graphene Dirac cone

abstract:
  We investigate the influence of SiO2, Au, Ag, Cu, and Pt substrates on the
Raman spectrum of graphene. Experiments reveal particularly strong
modifications to the intensity, position, width, and shape of the Raman signal
of graphene on platinum, compared to that of suspended graphene. The
modifications strongly depend on the relative orientation of the graphene and
platinum lattices. These observations are theoretically investigated and shown
to originate from hybridization of electronic states in graphene and d-orbitals
in platinum. It is expected that, quite generally, hybridization between
graphene and any material with d-orbitals near the Fermi level will result in
an imprint on the graphene Dirac cone which depends sensitively on the relative
orientation of the respective lattices.


title:
Minimal spanning trees at the percolation threshold: a numerical
  calculation

abstract:
  The fractal dimension of minimal spanning trees on percolation clusters is
estimated for dimensions $d$ up to $d=5$. A robust analysis technique is
developed for correlated data, as seen in such trees. This should be a robust
method suitable for analyzing a wide array of randomly generated fractal
structures. The trees analyzed using these techniques are built using a
combination of Prim's and Kruskal's algorithms for finding minimal spanning
trees. This combination reduces memory usage and allows for simulation of
larger systems than would otherwise be possible. The path length fractal
dimension $d_{s}$ of MSTs on critical percolation clusters is found to be
compatible with the predictions of the perturbation expansion developed by
T.S.Jackson and N.Read [T.S.Jackson and N.Read, Phys.\ Rev.\ E \textbf{81},
021131 (2010)].


title: Movers and Shakers: Kinetic Energy Harvesting for the Internet of Things

abstract:
  Numerous energy harvesting wireless devices that will serve as building
blocks for the Internet of Things (IoT) are currently under development.
However, there is still only limited understanding of the properties of various
energy sources and their impact on energy harvesting adaptive algorithms.
Hence, we focus on characterizing the kinetic (motion) energy that can be
harvested by a wireless node with an IoT form factor and on developing energy
allocation algorithms for such nodes. In this paper, we describe methods for
estimating harvested energy from acceleration traces. To characterize the
energy availability associated with specific human activities (e.g., relaxing,
walking, cycling), we analyze a motion dataset with over 40 participants. Based
on acceleration measurements that we collected for over 200 hours, we study
energy generation processes associated with day-long human routines. We also
briefly summarize our experiments with moving objects. We develop energy
allocation algorithms that take into account practical IoT node design
considerations, and evaluate the algorithms using the collected measurements.
Our observations provide insights into the design of motion energy harvesters,
IoT nodes, and energy harvesting adaptive algorithms.


title:
Mean curvature, threshold dynamics, and phase field theory on finite
  graphs

abstract:
  In the continuum, close connections exist between mean curvature flow, the
Allen-Cahn (AC) partial differential equation, and the Merriman-Bence-Osher
(MBO) threshold dynamics scheme. Graph analogues of these processes have
recently seen a rise in popularity as relaxations of NP-complete combinatorial
problems, which demands deeper theoretical underpinnings of the graph
processes. The aim of this paper is to introduce these graph processes in the
light of their continuum counterparts, provide some background, prove the first
results connecting them, illustrate these processes with examples and identify
open questions for future study. We derive a graph curvature from the graph cut
function, the natural graph counterpart of total variation (perimeter). This
derivation and the resulting curvature definition differ from those in earlier
literature, where the continuum mean curvature is simply discretized, and bears
many similarities to the continuum nonlocal curvature or nonlocal means
formulation. This new graph curvature is not only relevant for graph MBO
dynamics, but also appears in the variational formulation of a discrete time
graph mean curvature flow. We prove estimates showing that the dynamics are
trivial for both MBO and AC evolutions if the parameters (the time-step and
diffuse interface scale, respectively) are sufficiently small (a phenomenon
known as "freezing" or "pinning") and also that the dynamics for MBO are
nontrivial if the time step is large enough. These bounds are in terms of graph
quantities such as the spectrum of the graph Laplacian and the graph curvature.
Adapting a Lyapunov functional for the continuum MBO scheme to graphs, we prove
that the graph MBO scheme converges to a stationary state in a finite number of
iterations. Variations on this scheme have recently become popular in the
literature as ways to minimize (continuum) nonlocal total variation.


title: A probabilistic solution to the Stroock-Williams equation

abstract:
  We consider the initial boundary value problem \begin{eqnarray*}u_t=\mu
u_x+\tfrac{1}{2}u_{xx}\qquad (t>0,x\ge0),\\u(0,x)=f(x)\qquad
(x\ge0),\\u_t(t,0)=\nu u_x(t,0)\qquad (t>0)\end{eqnarray*} of Stroock and
Williams [Comm. Pure Appl. Math. 58 (2005) 1116-1148] where $\mu,\nu\in
\mathbb{R}$ and the boundary condition is not of Feller's type when $\nu<0$. We
show that when $f$ belongs to $C_b^1$ with $f(\infty)=0$ then the following
probabilistic representation of the solution is valid:
\[u(t,x)=\mathsf{E}_x\bigl[f(X_t)\bigr]-\mathsf{E}_x\biggl[f'(X_t)\int_0^{\ell_t^0(X)}e^{-2(\nu-\mu)s}\,ds\biggr],\]
where $X$ is a reflecting Brownian motion with drift $\mu$ and $\ell^0(X)$ is
the local time of $X$ at $0$. The solution can be interpreted in terms of $X$
and its creation in $0$ at rate proportional to $\ell^0(X)$. Invoking the law
of $(X_t,\ell_t^0(X))$, this also yields a closed integral formula for $u$
expressed in terms of $\mu$, $\nu$ and $f$.


title: Liouville-type theorems for the fourth order nonlinear elliptic equation

abstract:
  In this paper, we are concerned with Liouville-type theorems for the
nonlinear elliptic equation {equation*} \Delta^2 u=|x|^a |u|^{p-1}u\;\ {in}\;\
\Omega, {equation*}where $a \ge 0$, $p>1$ and $\Omega \subset \mathbb{R}^n$ is
an unbounded domain of $\mathbb{R}^n$, $n \ge 5$. We prove Liouville-type
theorems for solutions belonging to one of the following classes: stable
solutions and finite Morse index solutions (whether positive or sign-changing).
Our proof is based on a combination of the {\it Pohozaev-type identity}, {\it
monotonicity formula} of solutions and a {\it blowing down} sequence, which is
used to obtain sharper results.


title:
Simple one-pass algorithm for penalized linear regression with
  cross-validation on MapReduce

abstract:
  In this paper, we propose a one-pass algorithm on MapReduce for penalized
linear regression
  \[f_\lambda(\alpha, \beta) = \|Y - \alpha\mathbf{1} - X\beta\|_2^2 +
p_{\lambda}(\beta)\] where $\alpha$ is the intercept which can be omitted
depending on application; $\beta$ is the coefficients and $p_{\lambda}$ is the
penalized function with penalizing parameter $\lambda$. $f_\lambda(\alpha,
\beta)$ includes interesting classes such as Lasso, Ridge regression and
Elastic-net. Compared to latest iterative distributed algorithms requiring
multiple MapReduce jobs, our algorithm achieves huge performance improvement;
moreover, our algorithm is exact compared to the approximate algorithms such as
parallel stochastic gradient decent. Moreover, what our algorithm distinguishes
with others is that it trains the model with cross validation to choose optimal
$\lambda$ instead of user specified one.
  Key words: penalized linear regression, lasso, elastic-net, ridge, MapReduce


title: SAHER: Secure and Efficient Routing in Sensor Networks

abstract:
  As an increasing amount of research is being done on various applications of
sensor networks in adversarial environments, ensuring secure routing becomes of
critical importance for the success of such deployments. The problem of
designing a secure routing protocol for ad hoc networks has been already
addressed, yet, there exists no complete solution that meets the specific
requirements of sensor networks, where nodes are extremely constrained in terms
of both power and computational resources. Thus, we propose a new protocol that
is not built solely around security but also has efficiency and simplicity
among its main goals. We propose the Secure Ad Hoc Efficient Routing protocol
(SAHER) which employs a two-tier architecture based on node clustering. Also,
we combine mechanisms like localscale geographic routing, per-node reputation
tables, credit based alternate route enforcement and cumulative authentication.
Using these techniques we examine ways to efficiently defend against the two
most common network layer attacks: selective packet dropping and message
flooding. Further, we consider join/leave operations which have not yet been
studied in sufficient depth for sensor networks from a security standpoint. We
provide a description of the protocol along with comprehensive experimental
evaluation under different node distributions, different proportions of
non-malicious vs. malicious nodes and different types of activity that
malicious nodes could exhibit.


title:
The traveling salesman problem in the Heisenberg group: upper bounding
  curvature

abstract:
  We show that if a subset $K$ in the Heisenberg group (endowed with the
Carnot-Carath\'{e}odory metric) is contained in a rectifiable curve, then it
satisfies a modified analogue of Peter Jones's geometric lemma. This is a
quantitative version of the statement that a finite length curve has a tangent
at almost every point. This condition complements that of \cite{FFP} except a
power 2 is changed to a power 4. Two key tools that we use in the proof are a
geometric martingale argument like that of \cite{Schul-TSP} as well as a new
curvature inequality in the Heisenberg group.


title:
Local Well-posedness for 2-D Schrodinger Equation on Irrational Tori and
  Bounds on Sobolev Norms

abstract:
  In this paper we consider the cubic Schrodinger equation in two space
dimensions on irrational tori. Our main result is an improvement of the
Strichartz estimates on irrational tori. Using this estimate we obtain a local
well-posedness result in H^s for s>131/416. We also obtain improved growth
bounds for higher order Sobolev norms.


title:
Beamforming Design for Multiuser Two-Way Relaying: A Unified Approach
  via Max-Min SINR

abstract:
  In this paper, we develop a unified framework for beamforming designs in
non-regenerative multiuser two-way relaying (TWR).


title:
Set intersection problems: Integrating projection and quadratic
  programming algorithms

abstract:
  Abstract. The Set Intersection Problem (SIP) is the problem of finding a
point in the intersection of convex sets. This problem is typically solved by
the method of alternating projections. To accelerate the convergence, the idea
of using Quadratic Programming (QP) to project a point onto the intersection of
halfspaces generated by the projection process was discussed in earlier papers.
This paper looks at how one can integrate projection algorithms together with
an active set QP algorithm. As a byproduct of our analysis, we show how to
accelerate an SIP algorithm involving box constraints, and how to extend a
version of the Algebraic Reconstruction Technique (ART) while preserving finite
convergence. Lastly, the warmstart property of active set QP algorithms is a
valuable property for the problem of projecting onto the intersection of convex
sets.


title:
FK-DLR properties of a quantum multi-type bose-gas with a repulsive
  interaction

abstract:
  The paper extends earlier results from \cite{SK}, \cite{SKS} about
infinite-volume quantum bosonic states (FK-DLR states) to the case of
multi-type particles with non-negative interactions. (An example is a quantum
Widom--Rowlinson model.) Following the strategy from \cite{SK}, \cite{SKS}, we
establish that, for the values of fugacity $z\in (0,1)$ and inverse temperature
$\beta >0$, finite-volume Gibbs states form a compact family in the
thermodynamic limit. Next, in dimension two we show that any limit-point state
(an FK-DLR state in the terminology adopted in \cite{SK}, \cite{SKS}) is
translation-invariant.


title: Single-Base DNA Discrimination via Transverse Ionic Transport

abstract:
  We suggest to discriminate single DNA bases via transverse ionic transport,
namely by detecting the ionic current that flows in a channel while a
single-stranded DNA is driven through an intersecting nanochannel. Our all-atom
molecular dynamics simulations indeed show that the ionic currents of the four
bases are statistically distinct, thus offering another possible approach to
sequence DNA.


title: High-Dimensional Bayesian Inference in Nonparametric Additive Models

abstract:
  A fully Bayesian approach is proposed for ultrahigh-dimensional nonparametric
additive models in which the number of additive components may be larger than
the sample size, though ideally the true model is believed to include only a
small number of components. Bayesian approaches can conduct stochastic model
search and fulfill flexible parameter estimation by stochastic draws. The
theory shows that the proposed model selection method has satisfactory
properties. For instance, when the hyperparameter associated with the model
prior is correctly specified, the true model has posterior probability
approaching one as the sample size goes to infinity; when this hyperparameter
is incorrectly specified, the selected model is still acceptable since
asymptotically it is proved to be nested in the true model. To enhance model
flexibility, two new $g$-priors are proposed and their theoretical performance
is examined. We also propose an efficient MCMC algorithm to handle the
computational issues. Several simulation examples are provided to demonstrate
the computational advantages of our method.


title: Strain-induced enhancement of coercivity in amorphous TbFeCo films

abstract:
  We report a strong size dependence of coercivity in amorphous ferrimagnetic
TbFeCo films. The as-deposited film exhibited a low saturation magnetization
(Ms=100 emu/cc) and a high perpendicular anisotropy (Ku=10^6 erg/cc). Hall-bar
devices were fabricated for characterizing the magneto-transport behaviors. A
significant increase in coercivity (up to 300 %) was observed at room
temperature as the width of Hall bar was reduced. The large coercivity
enhancement was attributed to the relaxation of film stress. The effect of
strain and dimensionality on the coercivity in TbFeCo makes it attractive for
tunable coercivity and the magnetization reversal in future nanoscale devices.


title: Transformation of stimulus correlations by the retina

abstract:
  Redundancies and correlations in the responses of sensory neurons seem to
waste neural resources but can carry cues about structured stimuli and may help
the brain to correct for response errors. To assess how the retina negotiates
this tradeoff, we measured simultaneous responses from populations of ganglion
cells presented with natural and artificial stimuli that varied greatly in
correlation structure. We found that pairwise correlations in the retinal
output remained similar across stimuli with widely different spatio-temporal
correlations including white noise and natural movies. Meanwhile, purely
spatial correlations tended to increase correlations in the retinal response.
Responding to more correlated stimuli, ganglion cells had faster temporal
kernels and tended to have stronger surrounds. These properties of individual
cells, along with gain changes that opposed changes in effective contrast at
the ganglion cell input, largely explained the similarity of pairwise
correlations across stimuli where receptive field measurements were possible.


title: The inertia of weighted unicyclic graphs

abstract:
  Let $G_w$ be a weighted graph. The \textit{inertia} of $G_w$ is the triple
$In(G_w)=\big(i_+(G_w),i_-(G_w), $ $ i_0(G_w)\big)$, where
$i_+(G_w),i_-(G_w),i_0(G_w)$ are the number of the positive, negative and zero
eigenvalues of the adjacency matrix $A(G_w)$ of $G_w$ including their
multiplicities, respectively. $i_+(G_w)$, $i_-(G_w)$ is called the
\textit{positive, negative index of inertia} of $G_w$, respectively. In this
paper we present a lower bound for the positive, negative index of weighted
unicyclic graphs of order $n$ with fixed girth and characterize all weighted
unicyclic graphs attaining this lower bound. Moreover, we characterize the
weighted unicyclic graphs of order $n$ with two positive, two negative and at
least $n-6$ zero eigenvalues, respectively.


title:
Approximate Bayesian Image Interpretation using Generative Probabilistic
  Graphics Programs

abstract:
  The idea of computer vision as the Bayesian inverse problem to computer
graphics has a long history and an appealing elegance, but it has proved
difficult to directly implement. Instead, most vision tasks are approached via
complex bottom-up processing pipelines. Here we show that it is possible to
write short, simple probabilistic graphics programs that define flexible
generative models and to automatically invert them to interpret real-world
images. Generative probabilistic graphics programs consist of a stochastic
scene generator, a renderer based on graphics software, a stochastic likelihood
model linking the renderer's output and the data, and latent variables that
adjust the fidelity of the renderer and the tolerance of the likelihood model.
Representations and algorithms from computer graphics, originally designed to
produce high-quality images, are instead used as the deterministic backbone for
highly approximate and stochastic generative models. This formulation combines
probabilistic programming, computer graphics, and approximate Bayesian
computation, and depends only on general-purpose, automatic inference
techniques. We describe two applications: reading sequences of degraded and
adversarially obscured alphanumeric characters, and inferring 3D road models
from vehicle-mounted camera images. Each of the probabilistic graphics programs
we present relies on under 20 lines of probabilistic code, and supports
accurate, approximately Bayesian inferences about ambiguous real-world images.


title: Improved search of PCA databases for spectro-polarimetric inversion

abstract:
  We describe a simple technique for the acceleration of spectro-polarimetric
inversions based on principal component analysis (PCA) of Stokes profiles. This
technique involves the indexing of the database models based on the sign of the
projections (PCA coefficients) of the first few relevant orders of principal
components of the four Stokes parameters. In this way, each model in the
database can be attributed a distinctive binary number of $2^{4n}$ bits, where
$n$ is the number of PCA orders used for the indexing. Each of these binary
numbers (indexes) identifies a group of "compatible" models for the inversion
of a given set of observed Stokes profiles sharing the same index. The complete
set of the binary numbers so constructed evidently determines a partition of
the database. The search of the database for the PCA inversion of
spectro-polarimetric data can profit greatly from this indexing. In practical
cases it becomes possible to approach the ideal acceleration factor of $2^{4n}$
as compared to the systematic search of a non-indexed database for a
traditional PCA inversion. This indexing method relies on the existence of a
physical meaning in the sign of the PCA coefficients of a model. For this
reason, the presence of model ambiguities and of spectro-polarimetric noise in
the observations limits in practice the number $n$ of relevant PCA orders that
can be used for the indexing.


title:
First-principles calculations of current-induced spin-transfer torques
  in magnetic domain walls

abstract:
  Current-induced spin-transfer torques (STTs) have been studied in Fe, Co and
Ni domain walls (DWs) by the method based on the first-principles noncollinear
calculations of scattering wave functions expanded in the tight-binding
linearized muffin-tin orbital (TB-LMTO) basis. The results show that the
out-of-plane component of nonadiabatic STT in Fe DW has localized form, which
is in contrast to the typical nonlocal oscillating nonadiabatic torques
obtained in Co and Ni DWs. Meanwhile, the degree of nonadiabaticity in STT is
also much greater for Fe DW. Further, our results demonstrate that compared to
the well-known first-order nonadiabatic STT, the torque in the third-order
spatial derivative of local spin can better describe the distribution of
localized nonadiabatic STT in Fe DW. The dynamics of local spin driven by this
third-order torques in Fe DW have been investigated by the
Landau-Lifshitz-Gilbert (LLG) equation. The calculated results show that with
the same amplitude of STTs the DW velocity induced by this third-order term is
about half of the wall speed for the case of the first-order nonadiabatic STT.


title:
Electron bunch energy and phase feed-forward stabilization system for
  the Mark V RF-linac free-electron laser

abstract:
  An amplitude and phase compensation system has been developed and tested at
the University of Hawai`i for the optimization of the RF drive system to the
Mark V Free-Electron Laser. Temporal uniformity of the RF drive is essential to
the generation of an electron beam suitable for optimal free-electron laser
performance and the operation of an inverse Compton scattering x-ray source.
The design of the RF measurement and compensation system is described in detail
and the results of RF phase compensation are presented. Performance of the
free-electron laser was evaluated by comparing the measured effects of phase
compensation with the results of a computer simulation. Finally, preliminary
results are presented for the effects of amplitude compensation on the
performance of the complete system.


title:
The differential $\rm d_4(h_6^3)$ in the Adams spectral sequence for
  spheres

abstract:
  We show that there is a non-trivial differential $d_4(h_6^3) =h_0^3g_4$ in
the mod 2 Adams spectral sequence for spheres. This together with the results
in
\cite{barratt_differentials_1970,lin_differential_1998,kan_differential_2001}
completely settle the differentials of $h_i^3$ for $i\ge4$. (The differentials
of $h_i^3$ for $i=0,1,2,3$ are well-known.) Our proof uses the Kevaire
invariant elements $\theta_i \in\pi_{2^{i+1}-2}^S$ for $i=4,5$ with the
properties $2\theta_4 =0$, $2\theta_5 =0$.


title:
Polynomial chaos based uncertainty quantification in Hamiltonian,
  multi-time scale, and chaotic systems

abstract:
  Polynomial chaos is a powerful technique for propagating uncertainty through
ordinary and partial differential equations. Random variables are expanded in
terms of orthogonal polynomials and differential equations are derived for the
expansion coefficients. Here we study the structure and dynamics of these
differential equations when the original system has Hamiltonian structure, has
multiple time scales, or displays chaotic dynamics. In particular, we prove
that the differential equations for the expansion coefficients in generalized
polynomial chaos expansions of Hamiltonian systems retain the Hamiltonian
structure relative to the ensemble average Hamiltonian. We connect this with
the volume-preserving property of Hamiltonian flows to show that, for an
oscillator with uncertain frequency, a finite expansion must fail at long
times, regardless of the order of the expansion. Also, using a two-time scale
forced nonlinear oscillator, we show that a polynomial chaos expansion of the
time-averaged equations captures uncertainty in the slow evolution of the
Poincar\'e section of the system and that, as the time scale separation
increases, the computational advantage of this procedure increases. Finally,
using the forced Duffing oscillator as an example, we demonstrate that when the
original dynamical system displays chaotic dynamics, the resulting dynamical
system from polynomial chaos also displays chaotic dynamics, limiting its
applicability.


title: The Chern-Ricci flow on smooth minimal models of general type

abstract:
  We show that on a smooth Hermitian minimal model of general type the
Chern-Ricci flow converges to a closed positive current on M. Moreover, the
flow converges smoothly to a Kahler-Einstein metric on compact sets away from
the null locus of K_M. This generalizes work of Tsuji and Tian-Zhang to
Hermitian manifolds, providing further evidence that the Chern-Ricci flow is a
natural generalization of the Kahler-Ricci flow.


title:
Extrinsic Jensen-Shannon Divergence: Applications to Variable-Length
  Coding

abstract:
  This paper considers the problem of variable-length coding over a discrete
memoryless channel (DMC) with noiseless feedback. The paper provides a
stochastic control view of the problem whose solution is analyzed via a newly
proposed symmetrized divergence, termed extrinsic Jensen-Shannon (EJS)
divergence. It is shown that strictly positive lower bounds on EJS divergence
provide non-asymptotic upper bounds on the expected code length. The paper
presents strictly positive lower bounds on EJS divergence, and hence
non-asymptotic upper bounds on the expected code length, for the following two
coding schemes: variable-length posterior matching and MaxEJS coding scheme
which is based on a greedy maximization of the EJS divergence.
  As an asymptotic corollary of the main results, this paper also provides a
rate-reliability test. Variable-length coding schemes that satisfy the
condition(s) of the test for parameters $R$ and $E$, are guaranteed to achieve
rate $R$ and error exponent $E$. The results are specialized for posterior
matching and MaxEJS to obtain deterministic one-phase coding schemes achieving
capacity and optimal error exponent. For the special case of symmetric
binary-input channels, simpler deterministic schemes of optimal performance are
proposed and analyzed.


title: The fundamental group functor as a Kan extension

abstract:
  We prove that the fundamental group functor from categorical Galois theory
may be computed as a Kan extension.


title: The observation of diffraction phases in matter wave scattering

abstract:
  We study the diffraction phase of different orders via the Dyson expansion
series, for ultracold atomic gases scattered by a standing-wave pulse. As these
diffraction phases are not observable in a single pulse scattering process, a
temporal Talbot-Lau interferometer consisting of two standing-wave pulses is
demonstrated experimentally with a Bose-Einstein condensate to explore this
physical effect. The role of the diffraction phases is clearly shown by the
second standing-wave pulse in the relative population of different momentum
states. Our experiments demonstrate obvious effects beyond the Raman-Nath
method, while agree well with our theory by including the diffraction phases.
In particular, the observed asymmetry in the dependence of the relative
population on the interval between two standing-wave pulses reflects the
diffraction phase differences. The role of interatomic interaction in the
Talbot-Lau interferometer is also discussed.


title: SU(2)-Cyclic Surgeries on Knots

abstract:
  A surgery on a knot in 3-sphere is called SU(2)-cyclic if it gives a manifold
whose fundamental group has no non-cyclic SU(2) representations. Using holonomy
perturbations on the Chern-Simons functional, we prove that the distance of two
SU(2)-cyclic surgery coefficients is bounded by the sum of the absolute values
of their numerators. This is an analog of Culler-Gordon-Luecke-Shalen's cyclic
surgery theorem.


title:
Antiprismless, or: Reducing Combinatorial Equivalence to Projective
  Equivalence in Realizability Problems for Polytopes

abstract:
  This article exhibits a 4-dimensional combinatorial polytope that has no
antiprism, answering a question posed by Bernt Lindst\"om. As a consequence,
any realization of this combinatorial polytope has a face that it cannot rest
upon without toppling over. To this end, we provide a general method for
solving a broad class of realizability problems. Specifically, we show that for
any semialgebraic property that faces inherit, the given property holds for
some realization of every combinatorial polytope if and only if the property
holds from some projective copy of every polytope. The proof uses the following
result by Below. Given any polytope with vertices having algebraic coordinates,
there is a combinatorial "stamp" polytope with a specified face that is
projectively equivalent to the given polytope in all realizations. Here we
construct a new stamp polytope that is closely related to Richter-Gebert's
proof of universality for 4-dimensional polytopes, and we generalize several
tools from that proof.


title: Log Analysis Techniques using Clustering in Network Forensics

abstract:
  Internet crimes are now increasing. In a row with many crimes using
information technology, in particular those using Internet, some crimes are
often carried out in the form of attacks that occur within a particular agency
or institution. To be able to find and identify the types of attacks, requires
a long process that requires time, human resources and utilization of
information technology to solve these problems. The process of identifying
attacks that happened also needs the support of both hardware and software as
well. The attack happened in the Internet network can generally be stored in a
log file that has a specific data format. Clustering technique is one of
methods that can be used to facilitate the identification process. Having
grouped the data log file using K-means clustering technique, then the data is
grouped into three categories of attack, and will be continued with the
forensic process that can later be known to the source and target of attacks
that exist in the network. It is concluded that the framework proposed can help
the investigator in the trial process.


title:
Effective Josephson dynamics in resonantly driven Bose-Einstein
  condensates

abstract:
  We show that the orbital Josephson effect appears in a wide range of driven
atomic Bose-Einstein condensed systems, including quantum ratchets, double
wells and box potentials. We use three separate numerical methods:
Gross-Pitaevskii equation, exact diagonalization of the few-mode problem, and
the Multi-Configurational Time-Dependent Hartree for Bosons algorithm. We
establish the limits of mean-field and few-mode descriptions, demonstrating
that they represent the full many-body dynamics to high accuracy in the weak
driving limit. Among other quantum measures, we compute the instantaneous
particle current and the occupation of natural orbitals. We explore four
separate dynamical regimes, the Rabi limit, chaos, the critical point, and
self-trapping; a favorable comparison is found even in the regimes of dynamical
instabilities or macroscopic quantum self-trapping. Finally, we present an
extension of the (t,t')-formalism to general time-periodic equations of motion,
which permits a systematic description of the long-time dynamics of resonantly
driven many-body systems, including those relevant to the orbital Josephson
effect.


title:
Schr\"odinger operators with \delta- and \delta'-interactions on
  Lipschitz surfaces and chromatic numbers of associated partitions

abstract:
  We investigate Schr\"odinger operators with \delta- and \delta'-interactions
supported on hypersurfaces, which separate the Euclidean space into finitely
many bounded and unbounded Lipschitz domains. It turns out that the
combinatorial properties of the partition and the spectral properties of the
corresponding operators are related. As the main result we prove an operator
inequality for the Schr\"odinger operators with \delta- and
\delta'-interactions which is based on an optimal colouring and involves the
chromatic number of the partition. This inequality implies various relations
for the spectra of the Schr\"odinger operators and, in particular, it allows to
transform known results for Schr\"odinger operators with \delta-interactions to
Schr\"odinger operators with \delta'-interactions.


title: The codegree threshold for 3-graphs with independent neighbourhoods

abstract:
  Given a family of 3-graphs $F$, we define its codegree threshold
$\mathrm{coex}(n, F)$ to be the largest number $d=d(n)$ such that there exists
an $n$-vertex 3-graph in which every pair of vertices is contained in at least
$d$ 3-edges but which contains no member of $F$ as a subgraph. Let $F_{3,2}$ be
the 3-graph on $\{a,b,c,d,e\}$ with 3-edges $\{abc,abd,abe,cde\}$.
  In this paper, we give two proofs that $\mathrm{coex}(n, F_{3,2})= n/3
+o(n)$, the first by a direct combinatorial argument and the second via a flag
algebra computation. Information extracted from the latter proof is then used
to obtain a stability result, from which in turn we derive the exact codegree
threshold for all sufficiently large $n$: $\mathrm{coex}(n, F_{3,2})= \lfloor
n/3 \rfloor -1$ if $n$ is congruent to $1$ modulo $3$, and $\lfloor n/3
\rfloor$ otherwise.
  In addition we determine the set of codegree-extremal configurations.


title: An Assessment Model for Cybercrime Investigation Capacity

abstract:
  Digital technologies are constantly changing, and with it criminals are
finding new ways to abuse these technologies. Cybercrime investigators, then,
must also keep their skills and knowledge up to date. This work proposes a
holistic training development model - specifically focused on cybercrime
investigation - that is based on improving investigator capability while also
considering the capacity of the investigator or unit. Along with a training
development model, a cybercrime investigation capacity assessment framework is
given for attempting to measure capacity throughout the education process.
First, a training development model is proposed that focuses on the expansion
of investigation capability as well as capacity of investigators and units.
Next, a capacity assessment model is given to evaluate the effectiveness of the
training program. A description of how the proposed model is being applied to
the development of training programs for cybercrime investigators in developing
countries will then be given, as well as already observed challenges. Finally,
concluding remarks as well as proposed future work is discussed.


title: The role of vector fields in modified gravity scenarios

abstract:
  Gravitational vector degrees of freedom typically arise in many examples of
modified gravity models. We start to systematically explore their role in these
scenarios, studying the effects of coupling gravitational vector and scalar
degrees of freedom. We focus on set-ups that enjoy a Galilean symmetry in the
scalar sector and an Abelian gauge symmetry in the vector sector. These
symmetries, together with the requirement that the equations of motion contain
at most two space-time derivatives, only allow for a small number of operators
in the Lagrangian for the gravitational fields. We investigate the role of
gravitational vector fields for two broad classes of phenomena that
characterize modified gravity scenarios. The first is self-acceleration: we
analyze in general terms the behavior of vector fluctuations around
self-accelerating solutions, and show that vanishing kinetic terms of vector
fluctuations lead to instabilities on cosmological backgrounds. The second
phenomenon is the screening of long range fifth forces by means of Vainshtein
mechanism. We show that if gravitational vector fields are appropriately
coupled to a spherically symmetric source, they can play an important role for
defining the features of the background solution and the scale of the
Vainshtein radius. Our general results can be applied to any concrete model of
modified gravity, whose low-energy vector and scalar degrees of freedom satisfy
the symmetry requirements that we impose.


title:
Gap sequences of 1-Weierstrass points on non-hyperelliptic curves of
  genus 10

abstract:
  In this paper, we compute the 1-gap sequences of 1-Weierstrass points on
non-hyperelliptic smooth projective curves of genus 10. Furthermore, the
geometry of such points is classified as flexes, sextactic and tentactic
points. Also, an upper bounds for their numbers are estimated.


title: The 3-rainbow index of a graph

abstract:
  Let $G$ be a nontrivial connected graph with an edge-coloring $c:
E(G)\rightarrow \{1,2,...,q\},$ $q \in \mathbb{N}$, where adjacent edges may be
colored the same. A tree $T$ in $G$ is a $rainbow tree$ if no two edges of $T$
receive the same color. For a vertex subset $S\subseteq V(G)$, a tree that
connects $S$ in $G$ is called an $S$-tree. The minimum number of colors that
are needed in an edge-coloring of $G$ such that there is a rainbow $S$-tree for
each $k$-subset $S$ of $V(G)$ is called $k$-rainbow index, denoted by
$rx_k(G)$. In this paper, we first determine the graphs whose 3-rainbow index
equals 2, $m,$ $m-1$, $m-2$, respectively. We also obtain the exact values of
$rx_3(G)$ for regular complete bipartite and multipartite graphs and wheel
graphs. Finally, we give a sharp upper bound for $rx_3(G)$ of 2-connected
graphs and 2-edge connected graphs, and graphs whose $rx_3(G)$ attains the
upper bound are characterized.


title:
Line bundle twisted chiral de Rham complex and bound states of D-branes
  on toric manifolds

abstract:
  In this note we calculate elliptic genus in various examples of twisted
chiral de Rham complex on two dimensional toric compact manifolds and
Calabi-Yau hypersurfaces in toric manifolds. At first the elliptic genus is
calculated for the line bundle twisted chiral de Rham complex on a compact
smooth toric manifold and K3 hypersurface in \mathbb{P}^{3} . Then we twist
chiral de Rham complex by sheaves localized on positive codimension
submanifolds in \mathbb{P}^{2} and calculate in each case the elliptic genus.
In the last example the elliptic genus of chiral de Rham complex on
\mathbb{P}^{2} twisted by SL(N) vector bundle with instanton number k is
calculated. In all cases considered we find the infinite tower of open string
oscillator contributions of the corresponding bound state of D-branes and
identify directly the open string boundary conditions and D-brane charges.


title:
Comparison of BES measurements of ion-scale turbulence with direct,
  gyrokinetic simulations of MAST L-mode plasmas

abstract:
  Observations of ion-scale (k_y*rho_i <= 1) density turbulence of relative
amplitude dn_e/n_e <= 0.2% are available on the Mega Amp Spherical Tokamak
(MAST) using a 2D (8 radial x 4 poloidal channel) imaging Beam Emission
Spectroscopy (BES) diagnostic. Spatial and temporal characteristics of this
turbulence, i.e., amplitudes, correlation times, radial and perpendicular
correlation lengths and apparent phase velocities of the density contours, are
determined by means of correlation analysis. For a low-density, L-mode
discharge with strong equilibrium flow shear exhibiting an internal transport
barrier (ITB) in the ion channel, the observed turbulence characteristics are
compared with synthetic density turbulence data generated from global,
non-linear, gyro-kinetic simulations using the particle-in-cell (PIC) code
NEMORB. This validation exercise highlights the need to include increasingly
sophisticated physics, e.g., kinetic treatment of trapped electrons,
equilibrium flow shear and collisions, to reproduce most of the characteristics
of the observed turbulence. Even so, significant discrepancies remain: an
underprediction by the simulations of the turbulence amplituide and heat flux
at plasma periphery and the finding that the correlation times of the
numerically simulated turbulence are typically two orders of magnitude longer
than those measured in MAST. Comparison of these correlation times with various
linear timescales suggests that, while the measured turbulence is strong and
may be `critically balanced', the simulated turbulence is weak.


title: Digital Data Security and Copyright Protection Using Cellular Automata

abstract:
  The emergence of many challenges and the rapid development of the means of
communications and computer networks and the Internet. Digital information
revolution has affected a lot on human societies. Data today has become
available in digital format (text, image, audio, and video), which led to the
emergence of many opportunities for creativity for innovation as well as the
emergence of a new kind of challenges


title:
On the increase of Gr\"onwall function value at the multiplication of
  its argument by a prime

abstract:
  We consider the function $G(n)=\frac{\sigma(n)}{n\log\log n}$ (where
$\sigma(n)=\sum_{d|n}d$) and set an imposed condition on its argument $n$, the
fulfillment of which is sufficient for the existence of a prime $p$, at which
$G(np)>G(n)$. This inequality is of interest in connection with the Robin's
inequality. The paper also presents the results of numerical experiment
conducted with superabundant numbers.


title:
Catch a Breath: Non-invasive Respiration Rate Monitoring via Wireless
  Communication

abstract:
  Radio signals are sensitive to changes in the environment, which for example
is reflected on the received signal strength (RSS) measurements of low-cost
wireless devices. This information has been used effectively in the past years
e.g. in device-free localization and tracking. Recent literature has also shown
that the fading information of the wireless channel can be exploited to
estimate the breathing rate of a person in a non-invasive manner; a research
topic we address in this paper. To the best of our knowledge, we demonstrate
for the first time that the respiration rate of a person can be accurately
estimated using only a single IEEE 802.15.4 compliant TX-RX pair. We exploit
channel diversity, low-jitter periodic communication, and oversampling to
enhance the breathing estimates, and make use of a decimation filter to
decrease the computational requirements of breathing estimation. In addition,
we develop a hidden Markov model (HMM) to identify the time instances when
breathing estimation is not possible, i.e., during times when other motion than
breathing occurs. We experimentally validate the accuracy of the system and the
results suggest that the respiration rate can be estimated with a mean error of
0.03 breaths per minute, the lowest breathing rate error reported to date using
IEEE 802.15.4 compliant transceivers. We also demonstrate that the breathing of
two people can be monitored simultaneously, a result not reported in earlier
literature.


title: Coded Slotted ALOHA with Varying Packet Loss Rate across Users

abstract:
  The recent research has established an analogy between successive
interference cancellation in slotted ALOHA framework and iterative
belief-propagation erasure-decoding, which has opened the possibility to
enhance random access protocols by utilizing theory and tools of
erasure-correcting codes. In this paper we present a generalization of the
and-or tree evaluation, adapted for the asymptotic analysis of the slotted
ALOHA-based random-access protocols, for the case when the contending users
experience different channel conditions, resulting in packet loss probability
that varies across users. We apply the analysis to the example of frameless
ALOHA, where users contend on a slot basis. We present results regarding the
optimal access probabilities and contention period lengths, such that the
throughput and probability of user resolution are maximized.


title: Effects of Fluctuating Energy Input on the Small Scales in Turbulence

abstract:
  In the standard cascade picture of 3D turbulent fluid flows, energy is input
at a constant rate at large scales. Energy is then transferred to smaller
scales by an intermittent process that has been the focus of a vast literature.
However, the energy input at large scales is not constant in most real
turbulent flows. We explore the signatures of these fluctuations of large scale
energy input on small scale turbulence statistics. Measurements were made in a
flow between oscillating grids, with Re up to 271, in which temporal variations
in the large scale energy input can be introduced by modulating the oscillating
grid frequency. We find that the Kolmogorov constant for second order
longitudinal structure functions depends on the magnitude of the fluctuations
in the large scale energy input. We can quantitatively predict the measured
change with a model based on Kolmogorov's refined similarity theory. The
effects of fluctuations of the energy input can also be observed using
structure functions conditioned on the instantaneous large scale velocity. A
linear parameterization using the curvature of the iconditional structure
functions provides a fairly good match with the measured changes in the
Kolmogorov constant. Conditional structure functions are found to provide a
more sensitive measure of the presence of fluctuations in the large scale
energy input than inertial range scaling coefficients.


title:
Semantics and pragmatics in actual software applications and in web
  search engines: exploring innovations

abstract:
  While new ways to use the Semantic Web are developed every week, which allow
the user to find information on web more accurately - for example in search
engines - some sophisticated pragmatic tools are becoming more important - for
example in web interfaces known as Social Intelligence, or in the most famous
Siri by Apple. The work aims to analyze whether and where we can identify the
boundary between semantics and pragmatics in the software used by analyzed
systems. examining how the linguistic disciplines are fundamental in their
progress. Is it possible to assume that the tools of social intelligence have a
pragmatic approach to the questions of the user, or it is just a use of a very
rich vocabulary, with the use of semantic tools?


title: Twins in words and long common subsequences in permutations

abstract:
  A large family of words must contain two words that are similar. We
investigate several problems where the measure of similarity is the length of a
common subsequence.
  We construct a family of n^{1/3} permutations on n letters, such that LCS of
any two of them is only cn^{1/3}, improving a construction of Beame, Blais, and
Huynh-Ngoc. We relate the problem of constructing many permutations with small
LCS to the twin word problem of Axenovich, Person and Puzynina. In particular,
we show that every word of length n over a k-letter alphabet contains two
disjoint equal subsequences of length cnk^{-2/3}.
  Many problems are left open.


title: On $\Pi$-supplemented subgroups of a finite group

abstract:
  A subgroup $H$ of a finite group $G$ is said to satisfy $\Pi$-property in $G$
if for every chief factor $L/K$ of $G$, $|G/K:N_{G/K}(HK/K\cap L/K)|$ is a
$\pi(HK/K\cap L/K)$-number. A subgroup $H$ of $G$ is called to be
$\Pi$-supplemented in $G$ if there exists a subgroup $T$ of $G$ such that
$G=HT$ and $H\cap T\leq I\leq H$, where $I$ satisfies $\Pi$-property in $G$. In
this paper, we investigate the structure of a finite group $G$ under the
assumption that some primary subgroups of $G$ are $\Pi$-supplemented in $G$.
The main result we proved improves a large number of earlier results.


title: Self-propelled Janus particles in a ratchet: Numerical simulations

abstract:
  Brownian transport of self-propelled overdamped microswimmers (like Janus
particles) in a two-dimensional periodically compartmentalized channel is
numerically investigated for different compartment geometries, boundary
collisional dynamics, and particle rotational diffusion. The resulting
time-correlated active Brownian motion is subject to rectification in the
presence of spatial asymmetry. We prove that ratcheting of Janus particles can
be orders of magnitude stronger than for ordinary thermal potential ratchets
and thus experimentally accessible. In particular, autonomous pumping of a
large mixture of passive particles can be induced by just adding a small
fraction of Janus particles.


title:
Coexistence of Half-Metallic Itinerant Ferromagnetism with Local-Moment
  Antiferromagnetism in Ba{0.60}K{0.40}Mn2As2

abstract:
  Magnetization, nuclear magnetic resonance, high-resolution x-ray diffraction
and magnetic field-dependent neutron diffraction measurements reveal a novel
magnetic ground state of Ba{0.60}K{0.40}Mn2As2 in which itinerant
ferromagnetism (FM) below a Curie temperature TC = 100 K arising from the doped
conduction holes coexists with collinear antiferromagnetism (AFM) of the Mn
local moments that order below a Neel temperature TN = 480 K. The FM ordered
moments are aligned in the tetragonal ab-plane and are orthogonal to the
AFM-ordered Mn moments that are aligned along the c-axis. The magnitude and
nature of the low-T FM ordered moment correspond to complete polarization of
the doped-hole spins (half-metallic itinerant FM) as deduced from magnetization
and ab-plane electrical resistivity measurements.


title: A set-operad of formal fractions and dendriform-like sub-operads

abstract:
  We introduce an operad of formal fractions, abstracted from the Mould operads
and containing both the Dendriform and the Tridendriform operads. We consider
the smallest set-operad contained in this operad and containing four specific
elements of arity two, corresponding to the generators and the associative
elements of the Dendriform and Tridendriform operads. We obtain a presentation
of this operad (by binary generators and quadratic relations) and an explicit
combinatorial description using a new kind of bi-colored trees. Similar results
are also presented for related symmetric operads.


title: Flow on sweeping networks

abstract:
  We introduce a cellular automaton model coupled with a transport equation for
flows on graphs. The direction of the flow is described by a switching process
where the switching probability dynamically changes according to the value of
the transported quantity in the neighboring cells. A motivation is pedestrian
dynamics in a small corridor where the propagation of people in a part of the
corridor can be either left or rightgoing. Under the assumptions of propagation
of chaos and mean-field limit, we derive a master equation and the
corresponding meanfield kinetic and macroscopic models. Steady--states are
computed and analyzed analytically and exhibit the possibility of multiple
meta-stable states and hysteresis.


title: Energy Diffusion in Harmonic System with Conservative Noise

abstract:
  We prove diffusive behaviour of the energy fluctuations in a system of
harmonic oscillators with a stochastic perturbation of the dynamics that
conserves energy and momentum. The results concern pinned systems or lattice
dimension $d\ge 3$, where the thermal diffusivity is finite.

categories: math-ph cond-mat.stat-mech math.MP math.PR


title: T-systems, networks and dimers

abstract:
  We study the solutions of the T-system for type A, also known as the
octahedron equation, viewed as a 2+1-dimensional discrete evolution equation.
These may be expressed entirely in terms of the stepped surface over which the
initial data are specified, via a suitably defined flat $GL_n$ connection which
embodies the integrability of this infinite rank system. By interpreting the
connection as the transfer operator for a directed graph or network with
weighted edges, we show that the solution at a given point is expressed as the
partition function for dimers on a bipartite graph dual to the "shadow" of the
point onto the initial data stepped surface. We extend the result to the case
of other geometries such as that of the evaporation of a cube corner crystal,
and to a reformulation of the Kenyon-Pemantle discrete hexahedron equation.

categories: math-ph cond-mat.stat-mech math.CO math.MP


title: Elementary Particles as Gates for Universal Quantum Computation

abstract:
  It is shown that there exists a mapping between the fermions of the Standard
Model (SM) represented as braids in the Bilson-Thompson model, and a set of
gates which can perform Universal Quantum Computation (UQC). This leads us to
conjecture that the "Computational Universe Hypothesis" (CUH) can be given a
concrete implementation in a new physical framework where elementary particles
and the gauge bosons (which intermediate interactions between fermions) are
interpreted as the components of a quantum computational network, with the
particles serving as quantum computational gates and the gauge fields as the
information carrying entities.


title: Englert-type solutions of d=11 supergravity

abstract:
  A family of geometries on S^7 arise as solutions of the classical equations
of motion in 11 dimensions. In addition to the conventional riemannian geometry
and the two exceptional Cartan-Schouten compact flat geometries with torsion,
one can also obtain non-flat geometries with torsion. This torsion is given
locally by the structure constants of a nonassociative geodesic loop in the
affinely connected space.


title: Complexity of short rectangles and periodicity

abstract:
  The Morse-Hedlund Theorem states that a bi-infinite sequence $\eta$ in a
finite alphabet is periodic if and only if there exists $n\in\N$ such that the
block complexity function $P_\eta(n)$ satisfies $P_\eta(n)\leq n$. In dimension
two, Nivat conjectured that if there exist $n,k\in\N$ such that the $n\times k$
rectangular complexity $P_{\eta}(n,k)$ satisfies $P_{\eta}(n,k)\leq nk$, then
$\eta$ is periodic. Sander and Tijdeman showed that this holds for $k\leq2$. We
generalize their result, showing that Nivat's Conjecture holds for $k\leq3$.
The method involves translating the combinatorial problem to a question about
the nonexpansive subspaces of a certain $\ZZ$ dynamical system, and then
analyzing the resulting system.


title: On a compact encoding of the swap automaton

abstract:
  Given a string $P$ of length $m$ over an alphabet $\Sigma$ of size $\sigma$,
a swapped version of $P$ is a string derived from $P$ by a series of local
swaps, i.e., swaps of adjacent symbols, such that each symbol can participate
in at most one swap. We present a theoretical analysis of the nondeterministic
finite automaton for the language $\bigcup_{P'\in\Pi_P}\Sigma^*P'$ (swap
automaton for short), where $\Pi_P$ is the set of swapped versions of $P$. Our
study is based on the bit-parallel simulation of the same automaton due to
Fredriksson, and reveals an interesting combinatorial property that links the
automaton to the one for the language $\Sigma^*P$. By exploiting this property
and the method presented by Cantone et al. (2010), we obtain a bit-parallel
encoding of the swap automaton which takes $O(\sigma^2\ceil{k/w})$ space and
allows one to simulate the automaton on a string of length $n$ in time
$O(n\ceil{k/w})$, where $\ceil{m/\sigma}\le k\le m$.


title:
Marrying Many-core Accelerators and InfiniBand for a New Commodity
  Processor

abstract:
  During the last 15 years, the supercomputing industry has been using
mass-produced, off-the-shelf components to build cluster computers. Such
components are not perfect for HPC purposes, but are cheap due to effect of
scale in their production. The coming exa-scale era changes the landscape:
exa-scale computers will contain components in quantities large enough to
justify their custom development and production.
  We propose a new heterogeneous processor, equipped with a network controller
and designed specifically for HPC. We then show how it can be used for
enterprise computing market, guaranteeing its widespread adoption and therefore
low production costs.


title: Current Direct Neutrino Mass Experiments

abstract:
  In this contribution we review the status and perspectives of direct neutrino
mass experiments. These experiments investigate the kinematics of
$\beta$-decays of specific isotopes ($^3$H, $^{187}$Re, $^{163}$Ho) to derive
model-independent information on the averaged electron (anti-) neutrino mass,
which is formed by the incoherent sum of the neutrino mass eigenstates
contributing to the electron neutrino. We first review the kinematics of
$\beta$-decay and the determination of the neutrino mass, before giving a brief
overview of past neutrino mass measurements (SN1987a-ToF studies, Mainz and
Troitsk experiments for $^3$H, cryo-bolometers for $^{187}$Re). We then
describe the Karlsruhe Tritium Neutrino (KATRIN) experiment which is currently
under construction at Karlsruhe Institute of Technology. The large-scale setup
will use the MAC-E-Filter principle pioneered earlier to push the sensitivity
down to a value of 200 meV(90% C.L.). KATRIN faces many technological
challenges that have to be resolved with regard to source intensity and
stability, as well as precision energy analysis and low background rate close
to the kinematic endpoint of tritium $\beta$-decay at 18.6 keV. We then review
new experimental approaches such as the MARE, ECHO and Project8 experiments,
which offer the promise to perform an independent measurement of the neutrino
mass in the sub-eV region. This variety of methods and the novel technologies
developed in all present and future experiments demonstrate the great potential
of direct neutrino mass experiments in providing vital information on the
absolute mass scale of neutrinos.


title: On uniformly rational varieties

abstract:
  We investigate basic properties of uniformly rational varieties, i.e. those
smooth varieties for which every point has a Zariski open neighborhood
isomorphic to an open subset of A^n. It is an open question of Gromov whether
all smooth rational varieties are uniformly rational. We discuss some potential
criteria that might allow one to show that they form a proper subclass in the
class of all smooth rational varieties. Finally we prove that small algebraic
resolutions and big resolutions of nodal cubic threefolds are uniformly
rational.


title: Attractive Tomonaga-Luttinger Liquid in a Quantum Spin Ladder

abstract:
  We present NMR measurements of a strong-leg spin-1/2 Heisenberg
antiferromagnetic ladder compound (C7H10N)2CuBr4 under magnetic fields up to 15
T in the temperature range from 1.2 K down to 50 mK. From the splitting of NMR
lines we determine the phase boundary and the order parameter of the
low-temperature (3-dimensional) long-range-ordered phase. In the
Tomonaga-Luttinger regime above the ordered phase, NMR relaxation reflects
characteristic power-law decay of spin correlation functions as 1/T1
T^(1/2K-1), which allows us to determine the interaction parameter K as a
function of field. We find that field-dependent K varies within the 1<K<2 range
which signifies attractive interaction between the spinless fermions in the
Tomonaga-Luttinger liquid.


title:
Perpendicular magnetization of Co20Fe50Ge30 films induced by MgO
  interface

abstract:
  Epitaxial growth of Co20Fe50Ge30 thin film on single crystal MgO (001)
substrate is reported. Structure characterization revealed (001)-oriented B2
order of CoFeGe well lattice matched with the MgO barrier. Perpendicular
magnetic anisotropy (PMA) was achieved in the MgO/CoFeGe/MgO structure with an
optimized magnetic anisotropy energy density (K) of 3 106 erg/cm3. The magnetic
anisotropy is found to depend strongly on the thickness of the MgO and CoFeGe
layers, indicating that the PMA of CoFeGe is contributed by the interfacial
anisotropy between CoFeGe and MgO. With reported low damping constant, CoFeGe
films are promising spintronic materials for achieving low switching current.


title: Photon gas in a finite box: thermodynamics and finite size effects

abstract:
  Thermodynamic properties of a photon gas in a small box are explored taking
into account finite size effects. General thermodynamic relations are derived
for this finite system. Photon gas thermodynamic functions are calculated for
the case of cuboid cavity on the basis of first principles. New finite size
effects are discussed.


title:
Resolving the effects of frequency dependent damping and quantum phase
  diffusion in YBa$_2$Cu$_3$O$_{7-x}$ Josephson junctions

abstract:
  We report on the study of the phase dynamics of high critical temperature
superconductor Josephson junctions. We realized YBa$_2$Cu$_3$O$_{7-x}$ (YBCO)
grain boundary (GB) biepitaxial junctions in the submicron scale, using low
loss substrates, and analyzed their dissipation by comparing the transport
measurements with Monte Carlo simulations. The behavior of the junctions can be
fitted using a model based on two quality factors, which results in a frequency
dependent damping. Moreover, our devices can be designed to have Josephson
energy of the order of the Coulomb energy. In this unusual energy range, phase
delocalization strongly influences the device's dynamics, promoting the
transition to a quantum phase diffusion regime. We study the signatures of such
a transition by combining the outcomes of Monte Carlo simulations with the
analysis of the device's parameters, the critical current and the temperature
behavior of the low voltage resistance $R_0$.


title: Pairs of boundary slopes with small differences

abstract:
  We show that, for any positive real number, there exists a knot in the
3-sphere admitting a pair of boundary slopes whose difference is at most the
given number.


title:
Intuitionistic First-Order Logic: Categorical Semantics via the
  Curry-Howard Isomorphism

abstract:
  This reports introduces a novel sound and complete semantics for first order
intuitionistic logic, in the framework of category theory and by the
computational interpretation of the logic based on the so-called Curry-Howard
isomorphism. Aside, a sound and complete semantics for the corresponding
lambda-calculus is derived, too. This semantics extends, in a way, the more
traditional meanings given by Heyting categories, the topos-theoretic
interpretation, and Kripke models. The feature which justifies the introduction
of this novel semantics is the fact that it is 'point-free', i.e., there is no
universe whose elements are used to interpret the logical terms. In other
words, terms do not denote individuals of some collection but, instead, they
denote the 'glue' which keeps together the interpretations of statements,
similarly to what happens in formal topology. Since the proposed semantics can
be trivially extended to all the first-order logical theories based on the
intuitionistic system (and, with some care, to minimal systems as well), the
semantics covers also all the predicative theories, even if some peculiar
aspects of these theories should be remarked.


title:
The existence of a smooth interface in the evolutionary elliptic
  Muskat--Verigin problem with nonlinear source

abstract:
  We study the two-phase Muskat--Verigin free-boundary problem for elliptic
equations with nonlinear sources. The existence of a smooth solution and a
smooth free boundary is proved locally in time by applying the parabolic
regularization of a condition on the free boundary.


title:
Reviewers' ratings and bibliometric indicators: hand in hand when
  assessing over research proposals?

abstract:
  The peer review system has been traditionally challenged due to its many
limitations especially for allocating funding. Bibliometric indicators may well
present themselves as a complement. Objective: We analyze the relationship
between peers' ratings and bibliometric indicators for Spanish researchers in
the 2007 National R&D Plan for 23 research fields. We analyze peers' ratings
for 2333 applications. We also gathered principal investigators' research
output and impact and studied the differences between accepted and rejected
applications. We used the Web of Science database and focused on the 2002-2006
period. First, we analyzed the distribution of granted and rejected proposals
considering a given set of bibliometric indicators to test if there are
significant differences. Then, we applied a multiple logistic regression
analysis to determine if bibliometric indicators can explain by themselves the
concession of grant proposals. 63.4% of the applications were funded.
Bibliometric indicators for accepted proposals showed a better previous
performance than for those rejected; however the correlation between peer
review and bibliometric indicators is very heterogeneous among most areas. The
logistic regression analysis showed that the main bibliometric indicators that
explain the granting of research proposals in most cases are the output (number
of published articles) and the number of papers published in journals that
belong to the first quartile ranking of the Journal Citations Report.
Bibliometric indicators predict the concession of grant proposals at least as
well as peer ratings. Social Sciences and Education are the only areas where no
relation was found, although this may be due to the limitations of the Web of
Science's coverage. These findings encourage the use of bibliometric indicators
as a complement to peer review in most of the analyzed areas.


title: Traces, Ultrapowers and the Pedersen-Petersen C*-Algebras

abstract:
  Our motivating question was whether all traces on a U-ultrapower of a
C*-algebra A, where U is a non-principal ultrafilter on N, are necessarily
U-limits of traces on A. We show that this is false so long as A has infinitely
many extremal traces, and even exhibit a 2^c size family of such traces on the
ultrapower. For this to fail even when A has finitely many traces implies that
A contains operators that can be expressed as sums of n+1 but not n
*-commutators, for arbitrarily large n. We show that this happens for a direct
sum of Pedersen-Petersen C*-algebras, and analyze some other interesting
properties of these C*-algebras.


title: Subconvexity for Half Integral Weight $L$-functions

abstract:
  We prove a subconvexity bound in the conductor aspect for $L(s,f,\chi)$ where
$f$ is a half integer weight modular form. This $L$-function has analytic
continuation and functional equation, but no Euler product. Due to the lack of
an Euler product, one does not expect a Riemann hypothesis for half integer
weight modular forms. Nevertheless one may speculate a Lindelof-type
hypothesis, and this current subconvexity result is an indication towards its
truth.


title: Islands of stability in motif distributions of random networks

abstract:
  We consider random non-directed networks subject to dynamics conserving
vertex degrees and study analytically and numerically equilibrium three-vertex
motif distributions in the presence of an external field, $h$, coupled to one
of the motifs. For small $h$ the numerics is well described by the "chemical
kinetics" for the concentrations of motifs based on the law of mass action. For
larger $h$ a transition into some trapped motif state occurs in
Erd\H{o}s-R\'enyi networks. We explain the existence of the transition by
employing the notion of the entropy of the motif distribution and describe it
in terms of a phenomenological Landau-type theory with a non-zero cubic term. A
localization transition should always occur if the entropy function is
non-convex. We conjecture that this phenomenon is the origin of the motifs'
pattern formation in real evolutionary networks.


title: Risk Without Return

abstract:
  Risk-only investment strategies have been growing in popularity as
traditional in- vestment strategies have fallen short of return targets over
the last decade. However, risk-based investors should be aware of four things.
First, theoretical considerations and empirical studies show that apparently
dictinct risk-based investment strategies are manifestations of a single
effect. Second, turnover and associated transaction costs can be a substantial
drag on return. Third, capital diversification benefits may be reduced. Fourth,
there is an apparent connection between performance and risk diversification.
To analyze risk diversification benefits in a consistent way, we introduce the
Risk Diversification Index (RDI) which measures risk concentrations and
complements the Herfindahl-Herschman Index (HHI) for capital concentrations.


title: Fine singularity analysis of solutions to Laplace equation

abstract:
  We present here a fine singularity analysis of solutions to the Laplace
equation in special polygonal domains in the plane. We assume piecewise
constant Neumann on one component of the boundary. Our motivation is to find
the rigorous proof the so-called Berg's effect.


title: Nonequilibrium chaos of disordered nonlinear waves

abstract:
  Do nonlinear waves destroy Anderson localization? Computational and
experimental studies yield subdiffusive nonequilibrium wave packet spreading.
Chaotic dynamics and phase decoherence assumptions are used for explaining the
data. We perform a quantitative analysis of the nonequilibrium chaos
assumption, and compute the time dependence of main chaos indicators - Lyapunov
exponents and deviation vector distributions. We find a slowing down of chaotic
dynamics, which does not cross over into regular dynamics up to the largest
observed time scales, still being fast enough to allow for a thermalization of
the spreading wave packet. Strongly localized chaotic spots meander through the
system as time evolves. Our findings confirm for the first time that
nonequilibrium chaos and phase decoherence persist, fueling the prediction of a
complete delocalization.


title:
Status of the ArDM Experiment: First results from gaseous argon
  operation in deep underground environment

abstract:
  The Argon Dark Matter (ArDM-1t) experiment is a ton-scale liquid argon (LAr)
double-phase time projection chamber designed for direct Dark Matter searches.
Such a device allows to explore the low energy frontier in LAr. After
successful operation on surface at CERN, the detector has been deployed
underground and is presently commissioned at the Canfranc Underground
Laboratory (LSC). In this paper, we describe the status of the installation and
present first results on data collected in gas phase.


title:
Computing a Compact Spline Representation of the Medial Axis Transform
  of a 2D Shape

abstract:
  We present a full pipeline for computing the medial axis transform of an
arbitrary 2D shape. The instability of the medial axis transform is overcome by
a pruning algorithm guided by a user-defined Hausdorff distance threshold. The
stable medial axis transform is then approximated by spline curves in 3D to
produce a smooth and compact representation. These spline curves are computed
by minimizing the approximation error between the input shape and the shape
represented by the medial axis transform. Our results on various 2D shapes
suggest that our method is practical and effective, and yields faithful and
compact representations of medial axis transforms of 2D shapes.


title: Long gaps between sign-changes of Gaussian Stationary Processes

abstract:
  We study the probability of a real-valued stationary process to be positive
on a large interval $[0,N]$. We show that if in some neighborhood of the origin
the spectral measure of the process has density which is bounded away from zero
and infinity, then the decay of this probability is bounded between two
exponential functions in $N$. This generalizes similar bounds obtained for
particular cases, such as a recent result by Artezana, Buckley, Marzo, Olsen.


title: On almost specification and average shadowing properties

abstract:
  In this paper we study relations between almost specification property,
asymptotic average shadowing property and average shadowing property for
dynamical systems on compact metric spaces. We show implications between these
properties and relate them to other important notions such as shadowing,
transitivity, invariant measures, etc. We provide examples that compactness is
a necessary condition for these implications to hold. As a consequence of our
methodology we also obtain a proof that limit shadowing in chain transitive
systems implies shadowing.


title:
Sub-cycle control of terahertz waveform polarization using all-optically
  induced transient metamaterials

abstract:
  Coherent radiation with frequencies ranging from 0.3 to 30 THz has recently
become accessible by femtosecond laser technology. Terahertz (THz) waves have
already found many applications in spectroscopy and imaging, and they can be
manipulated using static optical elements such as lenses, polarizers, and
filters. However, ultrafast modulation of THz radiation is required as well,
for instance in short-range wireless communication or for preparing shaped THz
transients for coherent control of numerous material excitations. Here, we
demonstrate an all-optically created transient metamaterial that permits to
manipulate the polarization of THz waveforms with sub-cycle precision. The
polarization-modulated pulses are potentially interesting for controlling
elementary motions such as vibrations of crystal lattices, rotations of
molecules, and the precession of spins.


title: Integrable systems on semidirect product Lie groups

abstract:
  We study integrable systems on the semidirect product of a Lie group and its
Lie algebra as the representation space of the adjoint action. Regarding the
tangent bundle of a Lie group as phase space endowed with this semidirect
product Lie group structure, we construct a class of symplectic submanifolds
equipped with a Dirac bracket on which integrable systems (in the
Adler-Kostant-Symes sense) are naturally built through collective dynamics. In
doing so, we address other issues as factorization, Poisson-Lie structures and
dressing actions. We show that the procedure becomes recursive for some
particular Hamilton functions, giving rise to a tower of nested integrable
systems.


title:
Generalized multiscale finite element methods for wave propagation in
  heterogeneous media

abstract:
  Numerical modeling of wave propagation in heterogeneous media is important in
many applications. Due to the complex nature, direct numerical simulations on
the fine grid are prohibitively expensive. It is therefore important to develop
efficient and accurate methods that allow the use of coarse grids. In this
paper, we present a multiscale finite element method for wave propagation on a
coarse grid. The proposed method is based on the Generalized Multiscale Finite
Element Method (GMsFEM). To construct multiscale basis functions, we start with
two snapshot spaces in each coarse-grid block where one represents the degrees
of freedom on the boundary and the other represents the degrees of freedom in
the interior. We use local spectral problems to identify important modes in
each snapshot space. These local spectral problems are different from each
other and their formulations are based on the analysis. To our best knowledge,
this is the first time where multiple snapshot spaces and multiple spectral
problems are used and necessary for efficient computations. Using the dominant
modes from local spectral problems, multiscale basis functions are constructed
to represent the solution space locally within each coarse block. These
multiscale basis functions are coupled via the symmetric interior penalty
discontinuous Galerkin method which provides a block diagonal mass matrix, and,
consequently, results in fast computations in an explicit time discretiza-
tion. Our methods' stability and spectral convergence are rigorously analyzed.
Numerical examples are presented to show our methods' performance. We also test
oversampling strategies. In particular, we discuss how the modes from different
snapshot spaces can affect the proposed methods' accuracy.


title: Combinatorics and Geometry of Transportation Polytopes: An Update

abstract:
  A transportation polytope consists of all multidimensional arrays or tables
of non-negative real numbers that satisfy certain sum conditions on subsets of
the entries. They arise naturally in optimization and statistics, and also have
interest for discrete mathematics because permutation matrices, latin squares,
and magic squares appear naturally as lattice points of these polytopes.
  In this paper we survey advances on the understanding of the combinatorics
and geometry of these polyhedra and include some recent unpublished results on
the diameter of graphs of these polytopes. In particular, this is a thirty-year
update on the status of a list of open questions last visited in the 1984 book
by Yemelichev, Kovalev and Kravtsov and the 1986 survey paper of Vlach.


title:
Radio Interferometric Calibration via Ordered-Subsets Algorithms: OS-LS
  and OS-SAGE calibrations

abstract:
  The main objective of this work is to accelerate the Maximum-Likelihood (ML)
estimation procedure in radio interferometric calibration. We introduce the
OS-LS and the OS-SAGE radio interferometric calibration methods, as a
combination of the Ordered-Subsets (OS) method with the Least-Squares (LS) and
Space Alternating Generalized Expectation maximization (SAGE) calibration
techniques, respectively. The OS algorithm speeds up the ML estimation and
achieves nearly the same level of accuracy of solutions as the one obtained by
the non-OS methods. We apply the OS-LS and OS-SAGE calibration methods to
simulated observations and show that these methods have a much higher
convergence rate relative to the conventional LS and SAGE techniques. Moreover,
the obtained results show that the OS-SAGE calibration technique has a superior
performance compared to the OS-LS calibration method in the sense of achieving
more accurate results while having significantly less computational cost.


title:
Measurement of the differential cross-section of B+ meson production in
  pp collisions at sqrt(s) = 7 TeV at ATLAS

abstract:
  The production cross-section of B+ mesons is measured as a function of
transverse momentum pT and rapidity y in proton--proton collisions at
center-of-mass energy sqrt(s) = 7 TeV, using 2.4 fb-1 of data recorded with the
ATLAS detector at the Large Hadron Collider. The differential production
cross-sections, determined in the range 9<pT<120 GeV and y<2.25, are compared
to next-to-leading-order theoretical predictions.


title: Concentration and Confidence for Discrete Bayesian Sequence Predictors

abstract:
  Bayesian sequence prediction is a simple technique for predicting future
symbols sampled from an unknown measure on infinite sequences over a countable
alphabet. While strong bounds on the expected cumulative error are known, there
are only limited results on the distribution of this error. We prove tight
high-probability bounds on the cumulative error, which is measured in terms of
the Kullback-Leibler (KL) divergence. We also consider the problem of
constructing upper confidence bounds on the KL and Hellinger errors similar to
those constructed from Hoeffding-like bounds in the i.i.d. case. The new
results are applied to show that Bayesian sequence prediction can be used in
the Knows What It Knows (KWIK) framework with bounds that match the
state-of-the-art.


title:
Adaptive Discrimination Scheme for Quantum Pulse Position Modulation
  Signals

abstract:
  In the communication scenario, we consider the problem of the discrimination
between the signals of the Quantum Pulse Position Modulation. We propose a
receiver scheme that employs repeated local measurements in distinct temporal
slots within the symbol time interval, adaptively chosen on the basis of the
outcomes in the previous slots. By employing Dynamic Programming to optimize
each measurement, we approach the theoretical performance limit much closer
than existing receiver schemes.