title: Quantum Vacuum and Inertial Reaction Force in Nonrelativistic QED

abstract:
  The possible connection between the electromagnetic zero-point field (ZPF)
and the inertia reaction force was first pointed out by Haisch, Rueda, and
Puthoff (Phys. Rev. A, 49, 678, 1994), and then by Rueda and Haisch following a
totally different and more satisfactory approach (Found. Phys., 28, 1057, 1998;
Phys. Letters A, 240, 115, 1998; Annalen der Physik, 10 (5), 393, 2001). In the
present paper, the approach taken by Rueda and Haisch will be followed, but the
analysis will be done within a formulation that uses nonrelativistic quantum
electrodynamics with the creation and annihilation operators rather than the
approach of Rueda and Haisch using stochastic electrodynamics. We analyze the
interaction between the zero-point field and an object under hyperbolic motion
(constant proper acceleration), and find that there arises a reaction force
which is proportional in magnitude, and opposite in direction, to the
acceleration. This is suggestive of what we know as inertia. We also point out
that the equivalence principle -- that inertial mass and gravitational mass
have the same values -- follows naturally using this approach. Inertial mass
and gravitational mass are not merely equal, they are the identical thing
viewed from two complementary perspectives (Annalen der Physik, 14 (8), 479,
2005). In the first case an object accelerating through the electromagnetic
zero-point field experiences resistance from the field. In the case of an
object held fixed in a gravitational field, the electromagnetic zero-point
field propagates on curved geodesics, in effect accelerating with respect to
the fixed object, thereby generating weight. Hence, the equivalence principle
does not need to be independently postulated.


title:
Lift and drag in intruders moving through hydrostatic granular media at
  high speeds

abstract:
  Recently, experiments showed that forces on intruders dragged horizontally
through dense, hydrostatic granular packings mainly depend on the local surface
orientation and can be seen as the sum of the forces exerted on small surface
elements. In order to understand such forces more deeply, we perform 2D
soft-sphere molecular dynamics simulation, on similar set up, of an intruder
dragged through a 50-50 bi-disperse granular packing, with diameters 0.30 and
0.34 cm. We measure, for both circular and half-circle shapes, the forces
parallel (drag) and perpendicular (lift) to the drag direction as functions of
the drag speed, with V=10.3-309 cm/s, and intruder depths, with D=3.75-37.5 cm.
The drag forces on an intruder monotonically increase with V and D, and are
larger for the circle. However, the lift force does not depend monotonically on
V and D, and this relationship is affected by the shape of the intruder. The
vertical force was negative for the half-circle, but for a small range of V and
D, we measure positive lift. We find no sign change for the lift on the circle,
which is always positive. The explanation for the nonmonotonic dependence is
related to the decrease in contacts on the intruder as V increases. This is
qualitatively similar to supersonic flow detachment from an obstacle. The
detachment picture is supported by simulation measurements of the velocity
field around the intruder and force profiles measured on its surface.


title:
The Spatial and Temporal Dependence of Coronal Heating by Alfven Wave
  Turbulence

abstract:
  The solar atmosphere may be heated by Alfven waves that propagate up from the
convection zone and dissipate their energy in the chromosphere and corona. To
further test this theory, we consider wave heating in an active region observed
on 2012 March 7. A potential field model of the region is constructed, and 22
field lines representing observed coronal loops are traced through the model.
Using a three-dimensional (3D) reduced magneto-hydrodynamics (MHD) code, we
simulate the dynamics of Alfven waves in and near the observed loops. The
results for different loops are combined into a single formula describing the
average heating rate Q as function of position within the observed active
region. We suggest this expression may be approximately valid also for other
active regions, and therefore may be used to construct 3D, time-dependent
models of the coronal plasma. Such models are needed to understand the role of
thermal non-equilibrium in the structuring and dynamics of the Sun's corona.


title: Discussion on the Cosmological Vacuum Energy

abstract:
  The present discussion contribution is some remarks concerning and review of
the proposal by one of us (C. Balazs) to explain the cosmological constant by
a/the principle of entropy. Used without further comment this principle of
entropy could easily lead to untrustable {\em nonlocalities}, but taking into
account that the long range correlations are rather to be understood as due to
initial condition set up the model for the cosmological constant being small by
one of us becomes quite viable.


title: Thermodynamics of quantum spin chains with competing interactions

abstract:
  We consider integrable quantum spin chains with competing interactions. We
apply the quantum transfer matrix approach to these spin chains. This allowed
us to derive a set of non-linear integral equations for the thermodynamics of
these spin chains. We provide numerical solution of these integral equations
for the entropy as function of magnetic field, temperature and the coupling
constant. This allow us to assess, at low but finite temperature, the picture
describing the ground state diagram for high spin chain and longer range
interchain interactions.


title:
Learning, Generalization, and Functional Entropy in Random Automata
  Networks

abstract:
  It has been shown \citep{broeck90:physicalreview,patarnello87:europhys} that
feedforward Boolean networks can learn to perform specific simple tasks and
generalize well if only a subset of the learning examples is provided for
learning. Here, we extend this body of work and show experimentally that random
Boolean networks (RBNs), where both the interconnections and the Boolean
transfer functions are chosen at random initially, can be evolved by using a
state-topology evolution to solve simple tasks. We measure the learning and
generalization performance, investigate the influence of the average node
connectivity $K$, the system size $N$, and introduce a new measure that allows
to better describe the network's learning and generalization behavior. We show
that the connectivity of the maximum entropy networks scales as a power-law of
the system size $N$. Our results show that networks with higher average
connectivity $K$ (supercritical) achieve higher memorization and partial
generalization. However, near critical connectivity, the networks show a higher
perfect generalization on the even-odd task.

categories: cs.NE cond-mat.dis-nn nlin.AO nlin.CD physics.bio-ph


title:
OptShrink: An algorithm for improved low-rank signal matrix denoising by
  optimal, data-driven singular value shrinkage

abstract:
  The truncated singular value decomposition (SVD) of the measurement matrix is
the optimal solution to the_representation_ problem of how to best approximate
a noisy measurement matrix using a low-rank matrix. Here, we consider the
(unobservable)_denoising_ problem of how to best approximate a low-rank signal
matrix buried in noise by optimal (re)weighting of the singular vectors of the
measurement matrix. We exploit recent results from random matrix theory to
exactly characterize the large matrix limit of the optimal weighting
coefficients and show that they can be computed directly from data for a large
class of noise models that includes the i.i.d. Gaussian noise case.
  Our analysis brings into sharp focus the shrinkage-and-thresholding form of
the optimal weights, the non-convex nature of the associated shrinkage function
(on the singular values) and explains why matrix regularization via singular
value thresholding with convex penalty functions (such as the nuclear norm)
will always be suboptimal. We validate our theoretical predictions with
numerical simulations, develop an implementable algorithm (OptShrink) that
realizes the predicted performance gains and show how our methods can be used
to improve estimation in the setting where the measured matrix has missing
entries.


title: Delaunay-type hypersurfaces in cohomogeneity one manifolds

abstract:
  Classical Delaunay surfaces are highly symmetric constant mean curvature
(CMC) submanifolds of space forms. We prove the existence of Delaunay-type
hypersurfaces in a large class of compact manifolds, using the geometry of
cohomogeneity one group actions and variational bifurcation techniques. Our
construction specializes to the classical examples in round spheres, and allows
to obtain Delaunay-type hypersurfaces in many other ambient spaces, ranging
from complex and quaternionic projective spaces to Kervaire exotic spheres.


title: Sets of integers avoiding congruent subsets

abstract:
  Consider the sets of integers $A$ that avoid any arrangement of $g$ congruent
$h$-subsets. Our findings refine and improve upon some results by Erd\H{o}s and
Harzheim about these sets.


title:
Modeling Of Blood Vessel Constriction In 2-D Case Using Molecular
  Dynamics Method

abstract:
  Blood vessel constriction is simulated with particle-based method using a
molecular dynamics authoring software known as Molecular Workbench (WM). Blood
flow and vessel wall, the only components considered in constructing a blood
vessel, are all represented in particle form with interaction potentials:
Lennard-Jones potential, push-pull spring potential, and bending spring
potential. Influence of medium or blood plasma is accommodated in plasma
viscosity through Stokes drag force. It has been observed that pressure p is
increased as constriction c is increased. Leakage of blood vessel starts at 80
% constriction, which shows existence of maximum pressure that can be overcome
by vessel wall.


title: When are two Coxeter orbifolds diffeomorphic?

abstract:
  One can define what it means for a compact manifold with corners to be a
"contractible manifold with contractible faces." Two combinatorially
equivalent, contractible manifolds with contractible faces are diffeomorphic if
and only if their 4-dimensional faces are diffeomorphic. It follows that two
simple convex polytopes are combinatorially equivalent if and only if they are
diffeomorphic as manifolds with corners. On the other hand, by a result of
Akbulut, for each n > 3, there are smooth, contractible n-manifolds with
contractible faces which are combinatorially equivalent but not diffeomorphic.
Applications are given to rigidity questions for reflection groups and smooth
torus actions.


title: How fast can we make interpreted Python?

abstract:
  Python is a popular dynamic language with a large part of its appeal coming
from powerful libraries and extension modules. These augment the language and
make it a productive environment for a wide variety of tasks, ranging from web
development (Django) to numerical analysis (NumPy). Unfortunately, Python's
performance is quite poor when compared to modern implementations of languages
such as Lua and JavaScript.
  Why does Python lag so far behind these other languages? As we show, the very
same API and extension libraries that make Python a powerful language also make
it very difficult to efficiently execute. Given that we want to retain access
to the great extension libraries that already exist for Python, how fast can we
make it?
  To evaluate this, we designed and implemented Falcon, a high-performance
bytecode interpreter fully compatible with the standard CPython interpreter.
Falcon applies a number of well known optimizations and introduces several new
techniques to speed up execution of Python bytecode. In our evaluation, we
found Falcon an average of 25% faster than the standard Python interpreter on
most benchmarks and in some cases about 2.5X faster.


title:
The shape of the cutoff in the synchrotron emission of SN 1006 observed
  with XMM-Newton

abstract:
  Synchrotron X-ray emission from the rims of young supernova remnants allows
us to study the high-energy tail of the electrons accelerated at the shock
front. The analysis of X-ray spectra can provide information on the physical
mechanisms that limit the energy achieved by the electrons in the acceleration
process. We aim at verifying whether the maximum electron energy in SN 1006 is
limited by synchrotron losses and at obtaining information on the shape of the
cutoff in the X-ray synchrotron emission. We analyzed the deep observations of
the XMM-Newton SN 1006 Large Program. We performed spatially resolved spectral
analysis of a set of small regions in the nonthermal limbs and studied the
X-ray spectra by adopting models that assume different electron spectra. We
found out that a loss-limited model provides the best fit to all the spectra
and this indicates that the shape of the cutoff in the electron momentum (p)
distribution has the form exp[-(p/p_cut)^2]. We also detected residual thermal
emission from shocked ambient medium and confirmed the reliability of previous
estimates of the post-shock density. Our results indicate that radiative losses
play a fundamental role in shaping the electron spectrum in SN 1006.


title: Applications of weak attraction theory in Out($F_n$)

abstract:
  Given a free group of rank r >= 3 and two exponentially growing outer
automorphisms {\psi} and {\phi} with dual lamination pairs {\Lambda^\pm}_{\psi}
and {\Lambda^\pm}_{\phi} associated to them, which satisfy a notion of
independence described in this paper, we will use the pingpong techniques
developed in recent works of Handel and Mosher to show that there exists an
integer M > 0, such that for every m, n >= M, {\psi}^m and {\phi}^n will freely
generate a group of rank two and every element of this free group which is not
conjugate to a power of the generators will be fully irreducible and
hyperbolic. The main corollary is a complete understanding of composition of
powers of fully irreducible elements. As bonus we will reprove a theorem in MCG
of surfaces with one boundary component and also have a new proof of a theorem
of Kapovich and Lustig. The final section also has a relativised version of the
main theorem which was recently used my Handel and Mosher to prove the second
bounded cohomology alternative for Out($F_n$) in arXiv:1511.06913


title:
Cliques and colorings in generalized Paley graphs and an approach to
  synchronization

abstract:
  Given a finite field, one can form a directed graph using the field elements
as vertices and connecting two vertices if their difference lies in a fixed
subgroup of the multiplicative group. If -1 is contained in this fixed
subgroup, then we obtain an undirected graph that is referred to as a
generalized Paley graph. In this paper we study generalized Paley graphs whose
clique and chromatic numbers coincide and link this theory to the study of the
synchronization property in 1-dimensional primitive affine permutation groups.


title: Molecular sensor based on graphene nanoribbons

abstract:
  In this work we study thermoelectric properties of graphene nanoribbons with
side-attached organic molecules. By adopting a single-band tight binding
Hamiltonian and the Green's function formalism, we calculated the transmission
and Seebeck coefficients for different hybrid systems. The corresponding
thermopower profiles exhibit a series of sharp peaks at the eigenenergies of
the isolated molecule. We study the effects of the temperature on the
thermoelectric response, and we consider random configurations of molecule
distributions, in different disorder regimes. The main characteristics of the
thermopower are not destroyed under temperature and disorder, indicating the
robustness of the system as a proposed molecular thermo-sensor device.


title:
Beyond second-order convergence in simulations of binary neutron stars
  in full general-relativity

abstract:
  Despite the recent rapid progress in numerical relativity, a convergence
order less than the second has so far plagued codes solving the Einstein-Euler
system of equations. We report simulations of the inspiral of binary neutron
stars in quasi-circular orbits computed with a new code employing high-order,
high-resolution shock-capturing, finite-differencing schemes that, for the
first time, go beyond the second-order barrier. In particular, without any
tuning or alignment, we measure a convergence order above three both in the
phase and in the amplitude of the gravitational waves. Because the new code is
able to calculate waveforms with very small phase errors already at modest
resolutions, we are able to obtain accurate estimates of tidal effects in the
inspiral that are essentially free from the large numerical viscosity typical
of lower-order methods, and even for the challenging large compactness and
small-deformability binary considered here. We find a remarkable agreement
between our Richardson-extrapolated waveform and the one from the tidally
corrected post-Newtonian (PN) Taylor-T4 model, with a de-phasing smaller than
0.2 radians during the seven orbits of the inspiral and up to the contact
point. Because our results can be used reliably to assess the validity of the
PN or other approximations at frequencies significantly larger than those
considered so far in the literature, they seem to exclude at these
compactnesses significant tidal amplifications from
next-to-next-to-leading--order terms in the PN expansion.


title: Solutions to the ultradiscrete KP hierarchy and its reductions

abstract:
  We propose a recursive representation of solutions to an ultradiscrete
analogue of the discrete KP hierarchy, which is the master equation of discrete
soliton equations. We also propose a class of solutions which can be used to
start the recursion. Finally, as an application, we discuss the compatibility
condition of ultradiscrete soliton equations.


title:
(Un)Decidability Results for Word Equations with Length and Regular
  Expression Constraints

abstract:
  We prove several decidability and undecidability results for the
satisfiability and validity problems for languages that can express solutions
to word equations with length constraints. The atomic formulas over this
language are equality over string terms (word equations), linear inequality
over the length function (length constraints), and membership in regular sets.
These questions are important in logic, program analysis, and formal
verification. Variants of these questions have been studied for many decades by
mathematicians. More recently, practical satisfiability procedures (aka SMT
solvers) for these formulas have become increasingly important in the context
of security analysis for string-manipulating programs such as web applications.
  We prove three main theorems. First, we give a new proof of undecidability
for the validity problem for the set of sentences written as a forall-exists
quantifier alternation applied to positive word equations. A corollary of this
undecidability result is that this set is undecidable even with sentences with
at most two occurrences of a string variable. Second, we consider Boolean
combinations of quantifier-free formulas constructed out of word equations and
length constraints. We show that if word equations can be converted to a solved
form, a form relevant in practice, then the satisfiability problem for Boolean
combinations of word equations and length constraints is decidable. Third, we
show that the satisfiability problem for quantifier-free formulas over word
equations in regular solved form, length constraints, and the membership
predicate over regular expressions is also decidable.


title: The Normal Form Theorem around Poisson Transversals

abstract:
  We prove a normal form theorem for Poisson structures around Poisson
transversals (also called cosymplectic submanifolds), which simultaneously
generalizes Weinstein's symplectic neighborhood theorem from symplectic
geometry and Weinstein's splitting theorem. Our approach turns out to be
essentially canonical, and as a byproduct, we obtain an equivariant version of
the latter theorem.


title:
Rate-Compatible Protograph-based LDPC Codes for Inter-Symbol
  Interference Channels

abstract:
  This letter produces a family of rate-compatible protograph-based LDPC codes
approaching the independent and uniformly distributed (i.u.d.) capacity of
inter-symbol interference (ISI) channels. This problem is highly nontrivial due
to the joint design of structured (protograph-based) LDPC codes and the state
structure of ISI channels. We describe a method to design nested high-rate
protograph codes by adding variable nodes to the protograph of a lower rate
code. We then design a family of rate-compatible protograph codes using the
extension method. The resulting protograph codes have iterative decoding
thresholds close to the i.u.d. capacity. Our results are supported by numerical
simulations.


title:
Short incomplete Gauss sums and rational points on metaplectic
  horocycles

abstract:
  In the present paper we investigate the limiting behaviour of short
incomplete Gauss sums at random argument as the number of terms goes to
infinity. We prove that the limit distribution is given by the distribution of
theta sums and differs from the limit law for long Gauss sums studied by the
author and Marklof. The key ingredient in the proof is an equidistribution
theorem for rational points on horocycles in the metaplectic cover of SL(2,R).


title:
A maximal-information color to gray conversion method for document
  images: Toward an optimal grayscale representation for document image
  binarization

abstract:
  A novel method to convert color/multi-spectral images to gray-level images is
introduced to increase the performance of document binarization methods. The
method uses the distribution of the pixel data of the input document image in a
color space to find a transformation, called the dual transform, which balances
the amount of information on all color channels. Furthermore, in order to
reduce the intensity variations on the gray output, a color reduction
preprocessing step is applied. Then, a channel is selected as the gray value
representation of the document image based on the homogeneity criterion on the
text regions. In this way, the proposed method can provide a
luminance-independent contrast enhancement. The performance of the method is
evaluated against various images from two databases, the ICDAR'03 Robust
Reading, the KAIST and the DIBCO'09 datasets, subjectively and objectively with
promising results. The ground truth images for the images from the ICDAR'03
Robust Reading dataset have been created manually by the authors.


title: Multiparton interactions: Theory and experimental findings

abstract:
  I give an introduction to multiparton interactions in proton-proton
collisions, with a focus on the perturbative regime. Recent experimental
results are discussed, as well as progress and open questions in theory.


title: From form factors to generalized parton distributions

abstract:
  I present an extraction of generalized parton distributions from selected
data on the electromagnetic nucleon form factors. The extracted distributions
can in particular be used to quantify the contribution to the proton spin from
the total angular momentum carried by valence quarks, as well as their
transverse spatial distribution inside the proton.


title:
Photon-Number-Splitting-attack resistant Quantum Key Distribution
  Protocols without sifting

abstract:
We propose a family of sifting-less quantum-key-distribution protocols which
use reverse-reconciliation, and are based on weak coherent pulses (WCPs)
polarized along m different directions. When m=4, the physical part of the
protocol is identical to most experimental implementations of BB84 and SARG04
protocols and they differ only in classical communications and data processing.
We compute their total keyrate as function of the channel transmission T, using
general information theoretical arguments and we show that they have a higher
keyrate than the more standard protocols, both for fixed and optimized average
photon number of the WCPs. When no decoy-state protocols (DSPs) are applied,
the scaling of the keyrate with transmission is improved from T2 for
BB84 to T^(1+1/(m-2)). If a DSP is applied, we show how the keyrates scale
linearly with T, with an improvement of the prefactor by 75.96 % for m=4. High
values of $ m $ allow to asymptotically approach the keyrate obtained with
ideal single photon pulses. The fact that the keyrates of these sifting-less
protocols are higher compared to those of the aforementioned more standard
protocols show that the latter are not optimal, since they do not extract all
the available secret key from the experimental correlations.


title: Generalized Schr\"odinger semigroups on infinite graphs

abstract:
  With appropriate notions of Hermitian vector bundles and connections over
weighted graphs which we allow to be locally infinite, we prove
Feynman-Kac-type representations for the corresponding semigroups and derive
several applications thereof.


title: Cremona groups of real surfaces

abstract:
  We give an explicit set of generators for various natural subgroups of the
real Cremona group Bir_R(P^2). This completes and unifies former results by
several authors.


title: CCAP for universal discrete quantum groups

abstract:
  We show that the discrete duals of the free orthogonal quantum groups have
the Haagerup property and the completely contractive approximation property.
Analogous results hold for the free unitary quantum groups and the quantum
automorphism groups of finite-dimensional C*-algebras. The proof relies on the
monoidal equivalence between free orthogonal quantum groups and SUq(2) quantum
groups, on the construction of a sufficient supply of bounded central
functionals for SUq(2) quantum groups, and on the free product techniques of
Ricard and Xu. Our results generalize previous work in the Kac setting due to
Brannan on the Haagerup property, and due to the second author on the CCAP.


title: Group localization and two problems of Levine

abstract:
  A. K. Bousfield's $H\mathbb Z$-localization of groups inverts homologically
two-connected homomorphisms of groups. J. P. Levine's algebraic closure of
groups inverts homomorphisms between finitely generated and finitely presented
groups which are homologically two-connected and for which the image normally
generates. We resolve an old problem concerning Bousfield $H\mathbb
Z$-localization of groups, and answer two questions of Levine regarding
algebraic closure of groups. In particular, we show that the kernel of the
natural homomorphism from a group $G$ to it's Bousfield $H\mathbb
Z$-localization is not always a $G$-perfect subgroup. In the case of algebraic
closure of groups, we prove the analogous result that this kernel is not always
an invisible subgroup.


title: Supersymmetric field theory with benign ghosts

abstract:
  We construct a supersymmetric (1+1)-dimensional field theory involving extra
derivatives and associated ghosts: the spectrum of the Hamiltonian is not
bounded from below, neither from above. In spite of that, there is neither
classical, nor quantum collapse and unitarity is preserved.


title: Phase diagram of spin-1/2 J1-J2 Heisenberg model on honeycomb lattice

abstract:
  We use density matrix renormalization group (DMRG) algorithm to study the
phase diagram of the spin-1/2 Heisenberg model on honeycomb lattice with first
(J1) and second (J2) neighbor antiferromagnetic interactions, where a Z2 spin
liquid region has been proposed. By implementing SU(2) symmetry in the DMRG
code, we are able to obtain accurate results for long cylinders with width
slightly over 15 lattice spacings and torus up to the size N=2*6*6. With
increasing J2, we find a Neel phase with vanishing spin gap and a plaquette
valence-bond (PVB) phase with non-zero spin gap. By extrapolating the square of
the staggered magnetic moment ms^2 on finite-size cylinders to thermodynamic
limit, we find the Neel order vanishing at J2/J1~0.22. For 0.25<J2/J1<0.35, we
find a possible PVB order, which shows a fast growing PVB decay length with
increasing system width. For 0.22<J2/J1<0.25, both spin and dimer orders are
weak for all systems we have studied, which is consistent with a possible spin
liquid phase or a deconfined quantum critical point. We present calculations of
the topological entanglement entropy, compare the DMRG results with the
variational Monte Carlo, and discuss possible scenarios in the thermodynamic
limit for this region.


title: He I D3 Observation of the 1984 May 22 M6.3 Solar Flare

abstract:
  He I D3 line has a unique response to the flare impact on the low solar
atmosphere and can be a powerful diagnostic tool for energy transport
processes. Using images obtained from the recently digitized films of Big Bear
Solar Observatory, we report D3 observation of the M6.3 flare on 1984 May 22,
which occurred in an active region with a circular magnetic polarity inversion
line (PIL). The impulsive phase of the flare starts with a main elongated
source that darkens in D3, inside of which bright emission kernels appear at
the time of the initial small peak in hard X-rays (HXRs). These flare cores
subsequently evolve into a sharp emission strand lying within the dark halo
simultaneously with the main peak in HXRs, reversing the overall source
contrast from -5% to 5%. The radiated energy in D3 during the main peak is
estimated to be about 10^30 ergs, which is comparable to that carried by
nonthermal electrons above 20 keV. Afterwards the flare proceeds along the
circular PIL in the counterclockwise direction to form a dark circular ribbon
in D3, which apparently mirrors the bright ribbons in Halpha and He I 10830 A.
All these ribbons last for over one hour in the late gradual phase. We suggest
that the present event resembles the so-called black-light flare that is
proposed based on continuum images, and that D3 darkening and brightening
features herein may be due to, respectively, the thermal conduction heating and
the direct precipitation of high-energy electrons.


title: On biharmonic submanifolds in non-positively curved manifolds

abstract:
  In the biharmonic submanifolds theory there is a generalized Chen's
conjecture which states that biharmonic submanifolds in a Riemannian manifold
with non-positive sectional curvature must be minimal. This conjecture turned
out false by a counter example of Y. L. Ou and L. Tang in \cite{Ou-Ta}. However
it remains interesting to find out sufficient conditions which guarantee this
conjecture to be true. In this note we prove that:
  1. Any complete biharmonic submanifold (resp. hypersurface) $(M, g)$ in a
Riemannian manifold $(N, h)$ with non-positive sectional curvature (resp. Ricci
curvature) which satisfies an integral condition: for some $p\in (0, +\infty)$,
$\int_{M}|\vec{H}|^{p}du_g<+\infty,$ where $\vec{H}$ is the mean curvature
vector field of $M\hookrightarrow N$, must be minimal. This generalizes the
recent results due to N. Nakauchi and H. Urakawa in \cite{Na-Ur1} and
\cite{Na-Ur2}.
  2. Any complete biharmonic submanifold (resp. hypersurface) in a Reimannian
manifold of at most polynomial volume growth whose sectional curvature (resp.
Ricci curvature) is non-positive must be minimal.
  3. Any complete biharmonic submanifold (resp. hypersurface) in a
non-positively curved manifold whose sectional curvature (resp. Ricci
curvature) is smaller that $-\epsilon$ for some $\epsilon>0$ which satisfies
that $\int_{B_\rho(x_0)}|\vec{H}|^{p+2}d\mu_g(p\geq0)$ is of at most polynomial
growth of $\rho$, must be minimal.
  We also consider $\varepsilon$-superbiharmonic submanifolds defined recently
in \cite{Wh} by G. Wheeler and prove similar results for
$\varepsilon$-superbiharmonic submanifolds, which generalize the result in
\cite{Wh}.


title: Optimal location problems with routing cost

abstract:
  In the paper a model problem for the location of a given number $N$ of points
in a given region $\Omega$ and with a given resources density $\rho(x)$ is
considered. The main difference between the usual location problems and the
present one is that in addition to the location cost an extra {\it routing
cost} is considered, that takes into account the fact that the resources have
to travel between the locations on a point-to-point basis. The limit problem as
$N\to\infty$ is characterized and some applications to airfreight systems are
shown.


title:
Invariance of Spooky Action at a Distance in Quantum Entanglement under
  Lorentz Transformation

abstract:
  We study the mechanism by which the particle-antiparticle entangled state
collapses instantaneously at a distance. By making two key assumptions, we are
able to show not only that instantaneous collapse of a wave function at a
distance is possible but also that it is an invariant quantity under Lorentz
transformation and compatible with relativity. In addition, we will be able to
detect in which situation a many-body entangled system exhibits the maximum
collapse speed among its entangled particles. Finally we suggest that every
force in nature acts via entanglement.


title:
The Krull filtration of the category of unstable modules over the
  Steenrod algebra

abstract:
  In the early 1990's, Lionel Schwartz gave a lovely characterization of the
Krull filtration of U, the category of unstable modules over the mod p Steenrod
algebra. Soon after, this filtration was used by the author as an
organizational tool in posing and studying some topological nonrealization
conjectures. In recent years the Krull filtration of U has been similarly used
by Castellana, Crespo, and Scherer in their study of H--spaces with finiteness
conditions, and Gaudens and Schwartz have given a proof of some of my
conjectures. In light of these topological applications, it seems timely to
better expose the algebraic properties of the Krull filtration.


title:
Anatomy of relativistic pion loop corrections to the electromagnetic
  nucleon coupling

abstract:
  We present a relativistic formulation of pion loop corrections to the
coupling of photons with nucleons on the light-front. Vertex and wave function
renormalization constants are computed to lowest order in the pion field,
including their nonanalytic behavior in the chiral limit, and studied
numerically as a function of the ultraviolet cutoff. Particular care is taken
to explicitly verify gauge invariance and Ward-Takahashi identity constraints
to all orders in the m_pi expansion. The results are used to compute the chiral
corrections to matrix elements of local operators, related to moments of
deep-inelastic structure functions. Finally, comparisons of results for
pseudovector and pseudoscalar coupling allows the resolution of a long-standing
puzzle in the computation of pion cloud corrections to structure function
moments.


title:
A dynamically-packed planetary system around GJ667C with three
  super-Earths in its habitable zone

abstract:
  Since low-mass stars have low luminosities, orbits at which liquid water can
exist on Earth-sized planets are relatively close-in, which produces Doppler
signals that are detectable using state-of-the-art Doppler spectroscopy. GJ
667C is already known to be orbited by two super-Earth candidates. We
investigate whether the data supports the presence of additional companions. We
obtain new Doppler measurements from HARPS extracted spectra and combined them
with those obtained from the PFS and HIRES spectrographs. We used Bayesian and
periodogram-based methods to re-assess the number of candidates and evaluated
the confidence of each detection. Among other tests, we validated the planet
candidates by analyzing correlations of each Doppler signal activity indices
and investigate quasi-periodicity. Doppler measurements of GJ 667C are
described better by six Keplerian-like signals: the two known candidates (b and
c); three additional few-Earth mass candidates with periods of 92, 62 and 39
days (d, e and f); a cold super-Earth in a 260-day orbit (g) and tantalizing
evidence of a $\sim$ 1 M$_\oplus$ object in a close-in orbit of 17 days (h). We
explore whether long-term stable orbits are compatible with the data by
integrating 8$\times 10^4$ solutions derived from the Bayesian samplings. The
system consisting of six planets is compatible with dynamically stable
configurations. As for the solar system, the most stable solutions do not
contain mean-motion resonances and are described well by analytic
Laplace-Lagrange solutions. The presence of a seventh planet (h) is supported
by the fact that it appears squarely centered on the only island of stability
left in the six-planet solution. Habitability assessments accounting for the
stellar flux, as well as tidal dissipation effects, indicate that three (maybe
four) planets are potentially habitable...


title: How to construct a gravitating quantum electron star

abstract:
  Motivated by the holographic study of Fermi surfaces, we develop methods to
solve Einstein gravity coupled to fermions and gauge fields, with AdS boundary
conditions and a chemical potential.


title: Near-Infrared Detection of a Super-Thin Disk in NGC 891

abstract:
  We probe the disk structure of the nearby, massive, edge-on spiral galaxy NGC
891 with sub-arcsecond resolution JHKs-band images covering ~+/-10 kpc in
radius and +/-5 kpc in height. We measure intrinsic surface brightness profiles
using realistic attenuation corrections constrained from near- and mid-infrared
(Spitzer) color maps and three-dimensional Monte-Carlo radiative-transfer
models. In addition to the well-known thin and thick disks, a super-thin disk
with 60-80 pc scale-height - comparable to the star-forming disk of the Milky
Way - is visibly evident and required to fit the attenuation-corrected light
distribution. Asymmetries in the super-thin disk light profile are indicative
of young, hot stars producing regions of excess luminosity and bluer
(attenuation-corrected) near-infrared color. To fit the inner regions of NGC
891, these disks must be truncated within ~3 kpc, with almost all their
luminosity redistributed in a bar-like structure 50% thicker than the thin
disk. There appears to be no classical bulge but rather a nuclear continuation
of the super-thin disk. The super-thin, thin, thick, and bar components
contribute roughly 30%, 42%, 13%, and 15% (respectively) to the total Ks-band
luminosity. Disk axial ratios (length/height) decrease from 30 to 3 from
super-thin to thick components. Both exponential and sech^2 vertical SB
profiles fit the data equally well. We find that the super-thin disk is
significantly brighter in the Ks-band than typically assumed in integrated SED
models of NGC 891: it appears that in these models the excess flux, likely
produced by young stars in the super-thin disk, has been mistakenly attributed
to the thin disk.


title:
H2 Excitation Structure on the Sightlines to delta Scorpius and zeta
  Ophiucus - First Results from the Sub-orbital Local Interstellar Cloud
  Experiment

abstract:
  We present the first science results from the Sub-orbital Local Interstellar
Cloud Experiment (SLICE): moderate resolution 1020-1070A spectroscopy of four
sightlines through the local interstellar medium. High signal-to-noise (S/N)
spectra of eta Uma, alpha Vir, delta Sco, and zeta Oph were obtained during a
21 April 2013 rocket flight. The SLICE observations constrain the density,
molecular photoexcitation rates, and physical conditions present in the
interstellar material towards delta Sco and zeta Oph. Our spectra indicate a
factor of two lower total N(H2) than previously reported for delta Sco, which
we attribute to higher S/N and better scattered light control in the new SLICE
observations. We find N(H2) = 1.5 x 10^{19} cm^{-2} on the delta Sco sightline,
with kinetic and excitation temperatures of 67 and 529 K, respectively, and a
cloud density of n_{H} = 56 cm^{-3}. Our observations of the bulk of the
molecular sightline toward zeta Oph are consistent with previous measurements
(N(H2) ~ 3 x 10^{20} cm^{-2} at T_{01} = 66 K and T_{exc} = 350 K). However, we
detect significantly more rotationally excited H2 towards zeta Oph than
previously observed. We infer a cloud density in the rotationally excited
component of n_{H} ~ 7600 cm^{-3} and suggest that the increased column
densities of excited H2 are a result of the ongoing interaction between zeta
Oph and its environment; also manifest as the prominent mid-IR bowshock
observed by WISE and the presence of vibrationally-excited H2 molecules
observed by HST.


title:
A Computational Approach to Politeness with Application to Social
  Factors

abstract:
  We propose a computational framework for identifying linguistic aspects of
politeness. Our starting point is a new corpus of requests annotated for
politeness, which we use to evaluate aspects of politeness theory and to
uncover new interactions between politeness markers and context. These findings
guide our construction of a classifier with domain-independent lexical and
syntactic features operationalizing key components of politeness theory, such
as indirection, deference, impersonalization and modality. Our classifier
achieves close to human performance and is effective across domains. We use our
framework to study the relationship between politeness and social power,
showing that polite Wikipedia editors are more likely to achieve high status
through elections, but, once elevated, they become less polite. We see a
similar negative correlation between politeness and power on Stack Exchange,
where users at the top of the reputation scale are less polite than those at
the bottom. Finally, we apply our classifier to a preliminary analysis of
politeness variation by gender and community.


title: MeV dark matter in the 3+1+1 model

abstract:
  The existence of light sterile neutrinos in the eV mass range with relatively
large mixing angles with the active neutrinos has been proposed for a variety
of reasons, including to improve the fit to the LSND and MiniBooNE neutrino
oscillation experiments, and reactor disappearance experiments. In ref. Phys.
Rev. D 84, 053001 (2011), it was shown that neutrino mixing with a heavier
sterile neutrino, in the mass range between 33 eV and several GeV, could
significantly affect and improve the agreement between neutrino oscillation
models with light sterile neutrinos and short baseline experimental results,
allowing for a new source of CP violation in appearance experiments and for
different apparent mixing angles in appearance and disappearance experiments.
However in refs. Phys. Rev. D 86, 033015 (2012) and JHEP 1204, 083 (2012) it
was shown that various collider experiment, supernovae, and cosmological
constraints can eliminate most of the parameter region where such a heavy
sterile neutrino can have a significant effect on neutrino oscillations. In
this paper we consider the effects of allowing a new light scalar in the MeV
mass region, which is a potential dark matter candidate, to interact with the
sterile neutrinos, and show that the resulting model is a consistent theory of
neutrino oscillation anomalies and dark matter which can also potentially
explain the INTEGRAL excess of 511 keV gamma rays in the central region of the
galaxy.


title: Anyons in integer quantum Hall magnets

abstract:
  Strongly correlated fractional quantum Hall liquids support fractional
excitations, which can be understood in terms of adiabatic flux insertion
arguments. A second route to fractionalization is through the coupling of
weakly interacting electrons to topologically nontrivial backgrounds such as in
polyacetylene. Here we demonstrate that electronic fractionalization combining
features of both these mechanisms occurs in noncoplanar itinerant magnetic
systems, where integer quantum Hall physics arises from the coupling of
electrons to the magnetic background. The topologically stable magnetic
vortices in such systems carry fractional (in general irrational) electronic
quantum numbers and exhibit Abelian anyonic statistics. We analyze the
properties of these topological defects by mapping the distortions of the
magnetic texture onto effective non-Abelian vector potentials. We support our
analytical results with extensive numerical calculations.


title: An improvement of the Beck-Fiala theorem

abstract:
  In 1981 Beck and Fiala proved an upper bound for the discrepancy of a set
system of degree d that is independent of the size of the ground set. In the
intervening years the bound has been decreased from 2d-2 to 2d-4. We improve
the bound to 2d-log* d.


title: Free Probability for Pairs of Faces I

abstract:
  We consider a notion of bi-freeness for systems of non-commutative random
variables with two faces, one of left variables and another of right variables.
This includes bi-free convolution operations, bi-free cumulants and the bi-free
central limit.


title:
The imprint of the crustal magnetic field on the thermal spectra and
  pulse profiles of isolated neutron stars

abstract:
  Isolated neutron stars (NSs) show a bewildering variety of astrophysical
manifestations, presumably shaped by the magnetic field strength and topology
at birth. Here, using state-of-the art calculations of the coupled magnetic and
thermal evolution of NSs, we compute the thermal spectra and pulse profiles
expected for a variety of initial magnetic field configurations. In particular,
we contrast models with purely poloidal magnetic fields to models dominated by
a strong internal toroidal component. We find that, while the former displays
double peaked profiles and very low pulsed fractions, in the latter, the
anisotropy in the surface temperature produced by the toroidal field often
results in a single pulse profile, with pulsed fractions that can exceed the
50-60% level even for perfectly isotropic local emission. We further use our
theoretical results to generate simulated "observed" spectra, and show that
blackbody (BB) fits result in inferred radii that can be significantly smaller
than the actual NS radius, even as low as ~ 1-2 km for old NSs with strong
internal toroidal fields and a high absorption column density along their line
of sight. We compute the size of the inferred BB radius for a few
representative magnetic field configurations, NS ages, and magnitudes of the
column density. Our theoretical results are of direct relevance to the
interpretation of X-ray observations of isolated NSs, as well as to the
constraints on the equation of state of dense matter through radius
measurements.


title:
Singular limiting induced from continuum solutions and the problem of
  dynamic cavitation

abstract:
  In the works of K.A. Pericak-Spector and S. Spector \cite{ps88, ps98} a class
of self-similar solutions are constructed for the equations of radial isotropic
elastodynamics that describe cavitating solutions. Cavitating solutions
decrease the total mechanical energy and provide a striking example of
non-uniqueness of entropy weak solutions (for polyconvex energies) due to
point-singularities at the cavity. To resolve this paradox, we introduce the
concept of singular limiting induced from continuum solution (or
slic-solution), according to which a discontinuous motion is a slic-solution if
its averages form a family of smooth approximate solutions to the problem. It
turns out that there is an energetic cost for creating the cavity, which is
captured by the notion of slic-solution but neglected by the usual entropic
weak solutions. Once this cost is accounted for, the total mechanical energy of
the cavitating solution is in fact larger than that of the homogeneously
deformed state. We also apply the notion of slic-solutions to a one-dimensional
example describing the onset of fracture, and to gas dynamics in Langrangean
coordinates with Riemann data inducing vacuum in the wave fan.


title: Development of the ALMA-North America Sideband-Separating SIS Mixers

abstract:
  As the Atacama Large Millimeter/submillimeter Array (ALMA) nears completion,
73 dual-polarization receivers have been delivered for each of Bands 3 (84-116
GHz) and 6 (211-275 GHz). The receivers use sideband-separating superconducting
Nb/Al-AlOx/Nb tunnel-junction (SIS) mixers, developed for ALMA to suppress
atmospheric noise in the image band. The mixers were designed taking into
account dynamic range, input return loss, and signal-to-image conversion (which
can be significant in SIS mixers). Typical SSB receiver noise temperatures in
Bands 3 and 6 are 30 K and 60 K, resp., and the image rejection is typically 15
dB.


title: Ultraparacompactness and Ultranormality

abstract:
  In this note, we shall overview some results related to ultraparacompactness
and ultranormality in the general topological and point-free contexts. This
note contains some standard results and counterexamples along with some results
which are not that well known and even of my new results.


title: Stability, Instability, Canonical Energy and Charged Black Holes

abstract:
  We use the canonical energy method of Hollands and Wald to study the
stability properties of asymptotically flat, stationary solutions to a very
general class of theories, consisting of a set of coupled scalar fields and
p-form gauge fields, minimally coupled to gravity. We find that, provided
certain very weak assumptions are made on the coupling coefficients, the
canonical energy method can be extended to this class of theories. In
particular, we construct a quadratic form E on initial data perturbations, with
the properties that E > 0 on all perturbations indicates stability, while E < 0
on some perturbation indicates instability. Furthermore, we show that the
conditions needed for the existence of E allow for a stable definition of
asymptotic flatness. Finally, we extend the proof of the Gubser-Mitra
conjecture, given by Hollands and Wald, to this class of theories. In
particular, this shows that for sufficiently extended, charged black brane
solutions to such theories, thermodynamic instability implies dynamical
instability.


title: New Observables for Direct Detection of Axion Dark Matter

abstract:
  We propose new signals for the direct detection of ultralight dark matter
such as the axion. Axion or axion like particle (ALP) dark matter may be
thought of as a background, classical field. We consider couplings for this
field which give rise to observable effects including a nuclear electric dipole
moment, and axial nucleon and electron moments. These moments oscillate rapidly
with frequencies accessible in the laboratory, ~ kHz to GHz, given by the dark
matter mass. Thus, in contrast to WIMP detection, instead of searching for the
hard scattering of a single dark matter particle, we are searching for the
coherent effects of the entire classical dark matter field. We calculate
current bounds on such time varying moments and consider a technique utilizing
NMR methods to search for the induced spin precession. The parameter space
probed by these techniques is well beyond current astrophysical limits and
significantly extends laboratory probes. Spin precession is one way to search
for these ultralight particles, but there may well be many new types of
experiments that can search for dark matter using such time-varying moments.


title: Cosmic Axion Spin Precession Experiment (CASPEr)

abstract:
  We propose an experiment to search for QCD axion and axion-like-particle
(ALP) dark matter. Nuclei that are interacting with the background axion dark
matter acquire time-varying CP-odd nuclear moments such as an electric dipole
moment. In analogy with nuclear magnetic resonance, these moments cause
precession of nuclear spins in a material sample in the presence of an electric
field. Precision magnetometry can be used to search for such precession. An
initial phase of this experiment could cover many orders of magnitude in ALP
parameter space beyond the current astrophysical and laboratory limits. And
with established techniques, the proposed experimental scheme has sensitivity
to QCD axion masses m_a < 10^-9 eV, corresponding to theoretically
well-motivated axion decay constants f_a > 10^16 GeV. With further
improvements, this experiment could ultimately cover the entire range of masses
m_a < 10^-6 eV, complementary to cavity searches.

categories: hep-ph astro-ph.CO cond-mat.other hep-ex quant-ph


title: Air Shower Simulation and Hadronic Interactions

abstract:
  The aim of this report of the Working Group on Hadronic Interactions and Air
Shower Simulation is to give an overview of the status of the field,
emphasizing open questions and a comparison of relevant results of the
different experiments. It is shown that an approximate overall understanding of
extensive air showers and the corresponding hadronic interactions has been
reached. The simulations provide a qualitative description of the bulk of the
air shower observables. Discrepancies are however found when the correlation
between measurements of the longitudinal shower profile are compared to that of
the lateral particle distributions at ground. The report concludes with a list
of important problems that should be addressed to make progress in
understanding hadronic interactions and, hence, improve the reliability of air
shower simulations.


title:
Zeitreisen: Gravitation trifft Quantenphysik (Time Travel: Gravity Meets
  Quantum Physics)

abstract:
  An introduction is given to discussions on the possiblity of fabricating
spacetime geometries allowing time-travel scenarios with the help of matter
possessing typically quantum features. Those scenarios are considered in the
framework of quantum field theory and general relativity. Results established
in the literature excluding the possibility of time-travel are presented.


title:
The Apple Doesn't Fall Far From the (Metric) Tree: The Equivalence of
  Definitions

abstract:
  In this paper we prove the equivalence of definitions for metric trees and
for \delta-hyperbolic spaces. We point out how these equivalences can be used
to understand the geometric and metric properties of \delta-hyperbolic spaces
and its relation to CAT(\kappa) spaces.


title:
Thermodynamic fluctuations in solar photospheric three-dimensional
  convection simulations and observations

abstract:
  Numerical 3D radiative (M)HD simulations of solar convection are used to
understand the physical properties of the solar photosphere. To validate this
approach, it is important to check that no excessive thermodynamic fluctuations
arise as a consequence of the partially incomplete treatment of radiative
transfer. We investigate the realism of 3D convection simulations carried out
with the Stagger code. We compared the characteristic properties of several
spectral lines in solar disc centre observations with spectra synthesized from
the simulations. We degraded the synthetic spectra to the spatial resolution of
the observations using the continuum intensity distribution. We estimated the
necessary spectral degradation by comparing atlas spectra with averaged
observed spectra. In addition to deriving a set of line parameters directly, we
used the SIR code to invert the spectra. Most of the line parameters from the
observational data are matched well by the degraded simulation spectra. The
inversions predict a macroturbulent velocity below 10 m/s for the simulation at
full spatial resolution, whereas they yield ~< 1000 m/s at a spatial resolution
of 0.3". The temperature fluctuations in the inversion of the degraded
simulation do not exceed those from the observational data (of the order of
100-200 K rms for -2<log tau<-0.5). The comparison of line parameters in
spatially averaged profiles with the averaged values of line parameters in
spatially resolved profiles indicates a significant change of (average) line
properties at a spatial scale between 0.13" and 0.3". Up to a spatial
resolution of 0.3", we find no indications of the presence of excessive
thermodynamic fluctuations in the 3D HD simulation. To definitely confirm that
simulations without spatial degradation contain fully realistic thermodynamic
fluctuations requires observations at even better spatial resolution.


title:
High-temperature cuprate superconductors studied by x-ray Compton
  scattering and positron annihilation spectroscopies

abstract:
  The bulk Fermi surface in an overdoped ($x = 0.3$) single crystal of
La$_{2-x}$Sr$_{x}$CuO$_{4}$ has been observed by using x-ray Compton
scattering. This momentum density technique also provides a powerful tool for
directly seeing what the dopant Sr atoms are doing to the electronic structure
of La$_2$CuO$_{4}$. Because of wave function effects, positron annihilation
spectroscopy does not yield a strong signature of the Fermi surface in extended
momentum space, but it can be used to explore the role of oxygen defects in the
reservoir layers for promoting high temperature superconductivity.


title:
Constraining Superluminal Electron and Neutrino Velocities using the
  2010 Crab Nebula Flare and the IceCube PeV Neutrino Events

abstract:
  The observation of two PeV-scale neutrino events reported by Ice Cube can, in
principle, allows one to place constraints on Lorentz invariance violation
(LIV) in the neutrino sector. After first arguing that at least one of the
IceCube events was of extragalactic origin, I derive an upper limit for {\it
the difference} between putative superluminal neutrino and electron velocities
of $\le \sim 5.6 \times 10^{-19}$ in units where $c = 1$, confirming that the
observed PeV neutrinos could have reached Earth from extragalactic sources. I
further derive a new constraint on the superluminal electron velocity, obtained
from the observation of synchrotron radiation in the Crab Nebula flare of
September, 2010. The inference that the $>$ 1 GeV $\gamma$-rays from
synchrotron emission in the flare were produced by electrons of energy up to
$\sim 5.1$ PeV indicates the non-occurrence of vacuum \'{C}erenkov radiation by
these electrons. This implies a new, strong constraint on superluminal electron
velocities $\delta_e \le \sim 5 \times 10^{-21}$. It immediately follows that
one then obtains an upper limit on the superluminal neutrino velocity {\it
alone} of $\delta_{\nu} \le \sim 5.6 \times 10^{-19}$, many orders of magnitude
better than the time-of-flight constraint from the SN1987A neutrino burst.
However, if the electrons are {\it subluminal} the constraint on $|\delta_e|
\le \sim 8 \times 10^{-17}$, obtained from the Crab Nebula $\gamma$-ray
spectrum, places a weaker constraint on superluminal neutrino velocity of
$\delta_{\nu} \le \sim 8 \times 10^{-17}$.


title:
The mass-concentration relation in massive galaxy clusters at redshift
  ~1

abstract:
  Mass and concentration of clusters of galaxies are related and evolving with
redshift. We study the properties of a sample of 31 massive galaxy clusters at
high redshift, 0.8 < z < 1.5, using weak and strong lensing observations.
Concentration is a steep function of mass, c_{200} ~M_{200}^{-0.83 +-0.39},
with higher-redshift clusters being less concentrated. Mass and concentration
from the stacked analysis, M_{200}=(4.1+-0.4)x10^{14}M_Sun/h and
c_{200}=2.3+-0.2, are in line with theoretical results extrapolated from the
local universe. Clusters with signs of dynamical activity preferentially
feature high concentrations. We discuss the possibility that the whole sample
is a mix of two different kinds of haloes. Over-concentrated clusters might be
accreting haloes out of equilibrium in a transient phase of compression,
whereas less concentrated ones might be more relaxed.


title:
Shock Emergence in Supernovae: Limiting Cases and Accurate
  Approximations

abstract:
  We examine the dynamics of accelerating normal shocks in stratified planar
atmospheres, providing accurate fitting formulae for the scaling index relating
shock velocity to the initial density and for the post-shock acceleration
factor as functions of the polytropic and adiabatic indices which parameterize
the problem. In the limit of a uniform initial atmosphere there are analytical
formulae for these quantities. In the opposite limit of a very steep density
gradient the solutions match the outcome of shock acceleration in exponential
atmospheres.


title: Heralding an Arbitrary Decoherence-Free Qubit State

abstract:
  We present an optical device which is capable of heralding a variety of DFS
states which protect against collective noise. Specifically, it can prepare all
three basis states which span a DFS qutrit as well as an arbitrarily encoded
DFS qubit state. We also discuss an interferometric technique for determining
the amplitudes associated with an arbitrary encoding. The heralded state may
find use in coherent optical systems which exhibit collective correlations.


title:
Poincar\'e type inequalities for group measure spaces and related
  transportation cost inequalities

abstract:
  Let $G$ be a countable discrete group with an orthogonal representation
$\alpha$ on a real Hilbert space $H$. We prove $L_p$ Poincar\'e inequalities
for the group measure space $L_\infty(\Omega_H,\gamma)\rtimes G$, where both
the group action and the Gaussian measure space $(\Omega_H, \gamma)$ are
associated with the representation $\alpha$. The idea of proof comes from
Pisier's method on the boundedness of Riesz transform and Lust-Piquard's work
on spin systems. Then we deduce a transportation type inequality from the $L_p$
Poincar\'e inequalities in the general noncommutative setting. This inequality
is sharp up to a constant (in the Gaussian setting). Several applications are
given, including Wiener/Rademacher chaos estimation and new examples of
Rieffel's compact quantum metric spaces.


title:
Multiplicative Structures on the Twisted Equivariant K-theory of Finite
  Groups

abstract:
  Let $K$ be a finite group and let $G$ be a finite group acting on $K$ by
automorphisms. In this paper we study two different but intimately related
subjects: on the one side we classify all possible multiplicative and
associative structures with which one can endow the twisted $G$-equivariant
K-theory of $K$, and on the other, we classify all possible monoidal structures
with which one can endow the category of twisted and $G$-equivariant bundles
over $K$. We achieve this classification by encoding the relevant information
in the cochains of a sub double complex of the double bar resolution associated
to the semi-direct product $K \rtimes G$; we use known calculations of the
cohomology of $K$, $G$ and $K \rtimes G$ to produce concrete examples of our
classification.
  In the case in which $K=G$ and $G$ acts by conjugation, the multiplication
map $G \rtimes G \to G$ is a homomorphism of groups and we define a shuffle
homomorphism which realizes this map at the homological level. We show that the
categorical information that defines the Twisted Drinfeld Double can be
realized as the dual of the shuffle homomorphism applied to any 3-cocycle of
$G$. We use the pullback of the multiplication map in cohomology to classify
the possible ring structures that the Grothendieck ring of representations of
the Twisted Drinfeld Double may have, and we include concrete examples of this
procedure.


title: Maximum power operation of interacting molecular motors

abstract:
  We study the mechanical and thermodynamic properties of different traffic
models for kinesin which are relevant in biological and experimental contexts.
We find that motor-motor interactions play a fundamental role by enhancing the
thermodynamic efficiency at maximum power of the motors, as compared to the
non-interacting system, in a wide range of biologically compatible scenarios.
We furthermore consider the case where the motor-motor interaction directly
affects the internal chemical cycle and investigate the effect on the system
dynamics and thermodynamics.


title:
Phase Winding a Two-Component BEC in an Elongated Trap: Experimental
  Observation of Moving Magnetic Orders and Dark-bright Solitons

abstract:
  We experimentally investigate the phase winding dynamics of a harmonically
trapped two-component BEC subject to microwave induced Rabi oscillations
between two pseudospin components. While the single particle dynamics can be
explained by mapping the system to a two-component Bose-Hubbard model,
nonlinearities due to the interatomic repulsion lead to new effects observed in
the experiments: In the presence of a linear magnetic field gradient, a
qualitatively stable moving magnetic order that is similar to antiferromagnetic
order is observed after critical winding is achieved. We also demonstrate how
the phase winding can be used as a new tool to generate copious dark-bright
solitons in a two-component BEC, opening the door for new experimental studies
of these nonlinear features.


title:
A Semiparametric Bayesian Model for Detecting Synchrony Among Multiple
  Neurons

abstract:
  We propose a scalable semiparametric Bayesian model to capture dependencies
among multiple neurons by detecting their co-firing (possibly with some lag
time) patterns over time. After discretizing time so there is at most one spike
at each interval, the resulting sequence of 1's (spike) and 0's (silence) for
each neuron is modeled using the logistic function of a continuous latent
variable with a Gaussian process prior. For multiple neurons, the corresponding
marginal distributions are coupled to their joint probability distribution
using a parametric copula model. The advantages of our approach are as follows:
the nonparametric component (i.e., the Gaussian process model) provides a
flexible framework for modeling the underlying firing rates; the parametric
component (i.e., the copula model) allows us to make inference regarding both
contemporaneous and lagged relationships among neurons; using the copula model,
we construct multivariate probabilistic models by separating the modeling of
univariate marginal distributions from the modeling of dependence structure
among variables; our method is easy to implement using a computationally
efficient sampling algorithm that can be easily extended to high dimensional
problems. Using simulated data, we show that our approach could correctly
capture temporal dependencies in firing rates and identify synchronous neurons.
We also apply our model to spike train data obtained from prefrontal cortical
areas in rat's brain.


title:
Markov Approximations of Gibbs measures for long-range potentials on 1D
  lattices

abstract:
  We study one-dimensional lattice systems with pair-wise interactions of
infinite range. We show projective convergence of Markov measures to the unique
equilibrium state. For this purpose we impose a slightly stronger condition
than summability of variations on the regularity of the interaction. With our
condition we are able to explicitly obtain stretched exponential bounds for the
rate of mixing of the equilibrium state. Finally we show convergence for the
entropy of the Markov measures to that of the equilibrium state via the
convergence of their topological pressure.


title: Moduli spaces of ten-line arrangements with double and triple points

abstract:
  Two arrangements with the same combinatorial intersection lattice but whose
complements have different fundamental groups are called a Zariski pair. This
work finds that there are at most nine such pairs amongst all ten line
arrangements whose intersection points are doubles or triples. This result is
obtained by considering the moduli space of a given configuration table which
describes the intersection lattice. A complete combinatorial classification is
given of all arrangements of this type under a suitable assumption, producing a
list of seventy-one described in a table, most of which do not explicitly
appear in the literature. This list also includes other important
counterexamples: nine combinatorial arrangements that are not geometrically
realizable.


title:
An improved measurement of the 2\nu \beta \beta\ half-life of Xe-136
  with EXO-200

abstract:
  We report on an improved measurement of the 2\nu \beta \beta\ half-life of
Xe-136 performed by EXO-200. The use of a large and homogeneous time projection
chamber allows for the precise estimate of the fiducial mass used for the
measurement, resulting in a small systematic uncertainty. We also discuss in
detail the data analysis methods used for double-beta decay searches with
EXO-200, while emphasizing those directly related to the present measurement.
The Xe-136 2\nu \beta \beta\ half-life is found to be 2.165 +- 0.016 (stat) +-
0.059 (sys) x 10^21 years. This is the most precisely measured half-life of any
2\nu \beta \beta\ decay to date.


title: Simplicity of the C*-algebras of skew product k-graphs

abstract:
  We consider conditions on a $k$-graph $\Lambda$, a semigroup $S$ and a
functor $\eta : \Lambda \to S$ which ensure that the $C^*$-algebra of the
skew-product graph $\Lambda \times_\eta S$ is simple. Our results allow give
some necessary and sufficient conditions for the AF-core of a $k$-graph
$C^{*}$-algebra to be simple.


title: Radiatively Induced Type II seesaw and Vector-like 5/3 Charge Quarks

abstract:
  Understanding small neutrino masses in type II seesaw models with TeV scale
SM triplet Higgs bosons requires that its coupling with the standard model
Higgs doublet H be dialed down to be order eV to KeV, which is a fine-tuning by
a factor of $10^{-11}-10^{-8}$ with respect to the weak scale. We present a
SUSY extension of the type II seesaw model where this dimensionful small
coupling is radiatively induced, thus making its smallness natural. This model
has an exotic vector-like quark doublet which contains a quark X with electric
charge 5/3 and a top partner t'. We discuss in details the phenomenology of the
model paying special attention to the consequences of the interactions of the
the exotic heavy quarks and the scalars of the model. Implications for
neutrinoless double beta decay and for the LHC experiments are discussed in
detail. Remarkably, in this model both the seesaw triplet and the heavy quarks
can manifest at colliders in a host of different signatures, including some
that significantly differ from those of the minimal models. Depending on the
choice of the hierarchy of couplings, the decay of the heavy quarks and of the
seesaw triplet may be subject to bounds that can be tighter or looser than the
bounds from standard LHC searches. Furthermore we point out a new
short-distance contribution to neutrinoless double beta decay mediated by the
simultaneous propagation of the type II triplet and exotic fermions. Remarkably
this contribution to the neutrinoless double beta decay is parametrically quite
independent from the scale of the generated neutrino mass.


title: Broadcasting in Ad Hoc Multiple Access Channels

abstract:
  We study broadcast in multiple access channels in dynamic adversarial
settings. There is an unbounded supply of anonymous stations attached to a
synchronous channel. There is an adversary who injects packets into stations to
be broadcast on the channel. The adversary is restricted by injection rate,
burstiness, and by how many passive stations can be simultaneously activated by
providing them with packets. We consider deterministic distributed broadcast
algorithms, which are further categorized by their properties. We investigate
for which injection rates can algorithms attain bounded packet latency, when
adversaries are restricted to be able to activate at most one station per
round. The rates of algorithms we present make the increasing sequence
consisting of $\frac{1}{3}$, $\frac{3}{8}$ and $\frac{1}{2}$, reflecting the
additional features of algorithms. We show that injection rate $\frac{3}{4}$
cannot be handled with bounded packet latency.


title:
The Discrepant Kinematics of ORLs and CELs in NGC 7009 as a Function of
  Ionization Structure

abstract:
  We present spatially- and velocity-resolved echelle spectroscopy for NGC 7009
obtained with the UVES spectrograph at the European Southern Observatory's Very
Large Telescope. Our objective is to analyze the kinematics of emission lines
excited by recombination and collisions with electrons to determine whether
similarities or differences could be useful in elucidating the well-known
abundance discrepancy derived from them. We construct position-velocity maps
for recombination, fluorescence, charge transfer, and collisionally-excited
lines. We find a plasma component emitting in the C II, N II, O II, and Ne II
recombination lines whose kinematics are discrepant: They are incompatible with
the ionization structure derived from all other evidence and the kinematics
derived from all of these lines are unexpectedly very similar. We find direct
evidence for a recombination contribution to [N II] 5755. Once taken into
account, the electron temperatures from [N II], [O III], and [Ne III] agree at
a given position and velocity. The electron densities derived from [O II] and
[Ar IV] are consistent with direct imaging and the distribution of hydrogen
emission. The kinematics of the C II, N II, O II, and Ne II lines does not
coincide with the kinematics of the [O III] and [Ne III] forbidden emission,
indicating that there is an additional plasma component to the recombination
emission that arises from a different volume from that giving rise to the
forbidden emission from the parent ions within NGC 7009. Thus, the chemical
abundances derived from either type of line are correct only for the plasma
component from which they arise. Apart from [N II] 5755, we find no anomaly
with the forbidden lines usually used to determine chemical abundances in
ionized nebulae, so the abundances derived from them should be reliable for the
medium from which they arise.


title:
Understanding the Predictive Power of Computational Mechanics and Echo
  State Networks in Social Media

abstract:
  There is a large amount of interest in understanding users of social media in
order to predict their behavior in this space. Despite this interest, user
predictability in social media is not well-understood. To examine this
question, we consider a network of fifteen thousand users on Twitter over a
seven week period. We apply two contrasting modeling paradigms: computational
mechanics and echo state networks. Both methods attempt to model the behavior
of users on the basis of their past behavior. We demonstrate that the behavior
of users on Twitter can be well-modeled as processes with self-feedback. We
find that the two modeling approaches perform very similarly for most users,
but that they differ in performance on a small subset of the users. By
exploring the properties of these performance-differentiated users, we
highlight the challenges faced in applying predictive models to dynamic social
data.

categories: cs.SI cs.LG physics.soc-ph stat.AP stat.ML


title:
A nonconforming finite element method for the Stokes equations using the
  Crouzeix-Raviart element for the velocity and the standard linear element for
  the pressure

abstract:
  We present a finite element method for Stokes equations using the
Crouzeix-Raviart element for the velocity and the continuous linear element for
the pressure. We show that the inf-sup condition is satisfied for this pair.
Two numerical experiments are presented to support the theoretical results.


title: Monopole radiation in modified gravity

abstract:
  Modifications to General Relativity typically introduce a scalar degree of
freedom. Experimental constraints require that the "fifth" force produced by
this field must be screened in high density environments. An important
consequence of the screening mechanism is that the scalar charge of a
spherically symmetric expanding or pulsating object, such as a supernova or
variable star, is not conserved and monopole radiation can be emitted thereby.
We calculate the energy loss rate due to scalar monopole radiation in
supernovae and variable stars for a generalized model of f(R) gravity in which
the matter coupling strength beta is allowed to be much larger than unity. For
models which become screened at the gravitational potential of our galaxy,
monopole radiation constraints require beta < 100.


title: Quantum frameness for Charge-Parity-Time inversion symmetry

abstract:
  We develop a theory of charge-parity-time (CPT) frameness resources to
circumvent CPT-superselection. We construct and quantify such resources for
spin~0, $\frac{1}{2}$, 1, and Majorana particles and show that quantum
information processing is possible even with CPT superselection. Our method
employs a unitary representation of CPT inversion by considering the aggregate
action of CPT rather than the composition of separate C, P and T operations, as
some of these operations involve problematic anti-unitary representations.


title: On Behavioral Types for OSGi: From Theory to Implementation

abstract:
  This report presents our work on behavioral types for OSGi component systems.
It extends previously published work and presents features and details that
have not yet been published. In particular, we cover a discussion on behavioral
types in general, and Eclipse based implementation work on behavioral types .
The implementation work covers: editors, means for comparing types at
development and runtime, a tool connection to resolve incompatibilities, and an
AspectJ based infrastructure to ensure behavioral type correctness at runtime
of a system. Furthermore, the implementation comprises various auxiliary
operations. We present some evaluation work based on examples.


title:
Distributed Estimation and Detection with Bounded Transmissions over
  Gaussian Multiple Access Channels

abstract:
  A distributed inference scheme which uses bounded transmission functions over
a Gaussian multiple access channel is considered. When the sensor measurements
are decreasingly reliable as a function of the sensor index, the conditions on
the transmission functions under which consistent estimation and reliable
detection are possible is characterized. For the distributed estimation
problem, an estimation scheme that uses bounded transmission functions is
proved to be strongly consistent provided that the variance of the noise
samples are bounded and that the transmission function is one-to-one. The
proposed estimation scheme is compared with the amplify-and-forward technique
and its robustness to impulsive sensing noise distributions is highlighted. In
contrast to amplify-and-forward schemes, it is also shown that bounded
transmissions suffer from inconsistent estimates if the sensing noise variance
goes to infinity. For the distributed detection problem, similar results are
obtained by studying the deflection coefficient. Simulations corroborate our
analytical results.


title:
Galaxy Clusters in the Line of Sight to Background Quasars - III
  Multi-Object Spectroscopy

abstract:
  We present Gemini/GMOS-S multi-object spectroscopy of 31 galaxy cluster
candidates at redshifts between 0.2 and 1.0 and centered on QSO sight-lines
taken from Lopez et al. (2008). The targets were selected based on the presence
of a intervening MgII absorption system at a similar redshift to that of a
galaxy cluster candidate lying at a projected distance < 2 h^{-1}Mpc from the
QSO sight-line (a 'photometric-hit'). The absorption systems span rest-frame
equivalent widths between 0.015 and 2.028 angstroms. Our aim was 3-fold: 1)
identify the absorbing galaxies and determine their impact parameters, 2)
confirm the galaxy cluster candidates in the vicinity of each quasar sightline,
and 3) determine whether the absorbing galaxies reside in galaxy clusters. Our
main findings are: 1) the identification of 10 out of 24 absorbing galaxies
with redshifts up to 1.0955. 2) The spectroscopic confirmation of 20 out of 31
cluster/group candidates, with most of the confirmed clusters/groups at z <
0.7. 3) Following from the results above, the spectroscopic confirmation of 10
out of 14 photometric hits within ~ 650 km/s from galaxy clusters/groups, in
addition to 2 new ones related to galaxy group environments. These numbers
imply efficiencies of 71% in finding such systems with MOS spectroscopy. This
is a remarkable result since we defined a photometric hit as those
cluster-absorber pairs having a redshift difference dz = 0.1. Absorbing
cluster-galaxies hosting weak absorbers are consistent with lower star
formation activity than the rest, which produce strong absorption and agree
with typical MgII absorbing galaxies found in the literature. Our spectroscopic
confirmations lend support to the selection of photometric hits made in Lopez
et al. (2008).


title:
On multiplicity in restriction of tempered representations of $p$-adic
  groups

abstract:
  We establish an equality between two multiplicities: one in the restriction
of tempered representations of a $p$-adic group to its closed subgroup with the
same derived group; and one occurring in their corresponding component groups
in Langlands dual sides, so-called $\mathcal{S}$-groups, under working
hypotheses about the tempered local Langlands conjecture and the internal
structure of tempered $L$-packets. This provides a formula of the multiplicity
for $p$-adic groups by means of dimensions of irreducible representations of
their $\mathcal{S}$-groups.


title:
Affleck-Dine Baryogenesis and Inflation in Supergravity with Strongly
  Stabilized Moduli

abstract:
  Constructing models of inflation and/or baryogenesis in the context of N=1
supergravity is known to be difficult as the finite energy density during
inflation typically generates large (order the Hubble scale) mass terms. This
is the well-known eta problem in inflation. The same effect gives masses along
low energy flat directions of the scalar potential thus potentially preventing
Affleck-Dine baryogenesis to occur. It has been shown that adding a chiral
multiplet S coupled to the inflaton (with a shift symmetry) can serve to
stabilize the inflationary potential and allows one to derive simple
inflationary potentials without an eta problem. Here, we show that by coupling
the same stabilizing field S to the flat direction, may naturally lead to a
negative mass-squared contribution to the flat direction thus generating the
necessarily large vacuum expectation value needed to realize Affleck-Dine
baryogenesis. We trace the evolution of the inflaton, stabilizer, and flat
direction field, as well as a Polonyi-like modulus responsible for soft
supersymmetry breaking.


title: Cluster algebras arising from the infinity-gon

abstract:
  We introduce a handy construction of cluster algebras of type
$\mathbb{A}_{\infty}$, we give a complete classification of the cluster
algebras arising from the infinity-gon, and finally we construct the category
of the diagonals of the infinity-gon and show that it is triangle-equivalent to
the infinite cluster category of type $\mathbb{A}_{\infty}$ described by Holm
and J{\o}rgensen.


title:
Quench dynamics of one-dimensional bosons in a commensurate periodic
  potential: A quantum kinetic equation approach

abstract:
  Results are presented for the dynamics arising due to a sudden quench of a
boson interaction parameter with the simultaneous switching on of a
commensurate periodic potential, the latter providing a source of non-linearity
that can cause inelastic scattering. A quantum kinetic equation is derived
perturbatively in the periodic potential and solved within the leading order
gradient expansion. A two-particle irreducible formalism is employed to
construct the stress-momentum tensor and hence the conserved energy. The
dynamics is studied in detail in the phase where the boson spectrum remains
gapless. The periodic potential is found to give rise to multi-particle
scattering processes that relaxes the boson distribution function. At long
times the system is found to thermalize with a thermalization time that depends
in a non-monotonic way on the amount of energy injected into the system due to
the quantum quench. This non-monotonic behavior arises due to the competing
effect of an increase of phase space for scattering on the one hand, and an
enhancement of the orthogonality catastrophe on the other hand as the quench
amplitude is increased. The approach to equilibrium is found to be purely
exponential for large quench amplitudes, and more complex for smaller quench
amplitudes.


title:
Downlink Rate Distribution in Heterogeneous Cellular Networks under
  Generalized Cell Selection

abstract:
  Considering both small-scale fading and long-term shadowing, we characterize
the downlink rate distribution at a typical user equipment (UE) in a
heterogeneous cellular network (HetNet), where shadowing, following any general
distribution, impacts cell selection while fading does not. Prior work either
ignores the impact of channel randomness on cell selection or lumps all the
sources of randomness into a single variable, with cell selection based on the
instantaneous signal strength, which is unrealistic. As an application of the
results, we study the impact of shadowing on load balancing in terms of the
optimal per-tier selection bias needed for rate maximization.


title: Sasaki manifolds, Kaehler cone manifolds and biharmonic submanifolds

abstract:
  For a Legendrian submanifold $M$ of a Sasaki manifold $N$, we study
harmonicity and biharmonicity of the corresponding Lagrangian cone submanifold
C(M) of a Kaehler manifold C(N). We show that, if $C(M)$ is biharmonic in C(N),
then it is harmonic; and $M$ is proper biharmonic in $N$ if and only if C(M)
has a non-zero eigen-section of the Jacobi operator with the eigenvalue $m=dim
M$.


title:
Bound to succeed: Transcription factor binding site prediction and its
  contribution to understanding virulence and environmental adaptation in
  bacterial plant pathogens

abstract:
  Bacterial plant pathogens rely on a battalion of transcription factors to
fine-tune their response to changing environmental conditions and marshal the
genetic resources required for successful pathogenesis. Prediction of
transcription factor binding sites represents an important tool for elucidating
regulatory networks, and has been conducted in multiple genera of plant
pathogenic bacteria for the purpose of better understanding mechanisms of
survival and pathogenesis. The major categories of transcription factor binding
sites that have been characterized are reviewed here with emphasis on in silico
methods used for site identification and challenges therein, their
applicability to different types of sequence datasets, and insights into
mechanisms of virulence and survival that have been gained through binding site
mapping. An improved strategy for establishing E value cutoffs when using
existing models to screen uncharacterized genomes is also discussed.


title:
Design and Implementation of an Unmanned Vehicle using a GSM Network
  with Microcontrollers

abstract:
  Now-a-days, a lot of research is being carried out in the development of USVs
(Unmanned surface vehicles), UAVs (Unmanned Aerial Vehicles) etc. Now in case
of USVs generally, we have seen that wireless controlled vehicles use RF
circuits which suffer from many drawbacks such as limited working range,
limited frequency range and limited control. Moreover shooting infrared
outdoors on a bright sunny day is often problematic, since sunlight can
interfere with the infrared signal. Use of a GSM network (in the form of a
mobile phone, a cordless phone) for robotic control can overcome these
limitations. It provides the advantages of robust control, working range as
large as the coverage area of the service provider in comparison with that of
an IR system, no interference with other controllers. This paper presents a
Global System for Mobile Telecommunication (GSM) network based system which can
be used to remotely send streams of 4 bit data for control of USVs.
Furthermore, this paper describes the usage of the Dual Tone Multi-Frequency
(DTMF) function of the phone, and builds a microcontroller based circuit to
control the vehicle to demonstrate wireless data communication. Practical
result obtained showed an appreciable degree of accuracy of the system and
friendliness through the use of a microcontroller.


title:
The generator of spatial diffeomorphisms in the Koslowski- Sahlmann
  representation

abstract:
  A generalization of the representation underlying the discrete spatial
geometry of Loop Quantum Gravity, to accomodate states labelled by smooth
spatial geometries, was discovered by Koslowski and further studied by
Sahlmann. We show how to construct the diffeomorphism constraint operator in
this Koslowski- Sahlmann (KS) representation from suitable connection and triad
dependent operators. We show that the KS representation supports the action of
hitherto unnoticed "background exponential" operators which, in contrast to the
holonomy- flux operators, change the smooth spatial geometry label of the
states. These operators are shown to be quantizations of certain connection
dependent functions and play a key role in the construction of the
diffeomorphism constraint operator.


title: A note on the paper "Homomorphism with respect to a function"

abstract:
  We give a direct proof of the main result of the paper "Homomorphisms with
respect to a function" by K. Boulabiar and F. Gdara [1] without using the Axiom
of Choice.


title:
Kicked-Harper model vs On-Resonance Double Kicked Rotor Model: From
  Spectral Difference to Topological Equivalence

abstract:
  Recent studies have established that, in addition to the well-known kicked
Harper model (KHM), an on-resonance double kicked rotor model (ORDKR) also has
Hofstadter's butterfly Floquet spectrum, with strong resemblance to the
standard Hofstadter's spectrum that is a paradigm in studies of the integer
quantum Hall effect. Earlier it was shown that the quasi-energy spectra of
these two dynamical models (i) can exactly overlap with each other if an
effective Planck constant takes irrational multiples of 2*pi and (ii) will be
different if the same parameter takes rational multiples of 2*pi. This work
makes some detailed comparisons between these two models, with an effective
Planck constant given by 2*pi M/N, where M and N are coprime and odd integers.
It is found that the ORDKR spectrum (with two periodic kicking sequences having
the same kick strength) has one flat band and $N-1$ non-flat bands whose
largest width decays in power law as K to the power of N+2, where K is a
kicking strength parameter. The existence of a flat band is strictly proven and
the power law scaling, numerically checked for a number of cases, is also
analytically proven for a three-band case. By contrast, the KHM does not have
any flat band and its band width scales linearly with K. This is shown to
result in dramatic differences in dynamical behavior, such as transient (but
extremely long) dynamical localization in ORDKR, which is absent in KHM.
Finally, we show that despite these differences, there exist simple extensions
of KHM and ORDKR (upon introducing an additional periodic phase parameter) such
that the resulting extended KHM and ORDKR are actually topologically
equivalent, i.e., they yield exactly the same Floquet-band Chern numbers and
display topological phase transitions at the same kick strengths. A theoretical
derivation of this topological equivalence is provided.


title: Robustness and Directed Structures in Ecological Flow Networks

abstract:
  Robustness of ecological flow networks under random failure of arcs is
considered with respect to two different functionalities: coherence and
circulation. In our previous work, we showed that each functionality is
associated with a natural path notion: lateral path for the former and directed
path for the latter. Robustness of a network is measured in terms of the size
of the giant laterally connected arc component and that of the giant strongly
connected arc component, respectively. We study how realistic structures of
ecological flow networks affect the robustness with respect to each
functionality. To quantify the impact of realistic network structures, two null
models are considered for a given real ecological flow network: one is random
networks with the same degree distribution and the other is those with the same
average degree. Robustness of the null models is calculated by theoretically
solving the size of giant components for the configuration model. We show that
realistic network structures have positive effect on robustness for coherence,
whereas they have negative effect on robustness for circulation.

categories: q-bio.PE nlin.AO physics.soc-ph q-bio.MN


title: Competency Tracking for English as a Second or Foreign Language Learners

abstract:
  My system utilizes the outcomes feature found in Moodle and other learning
content management systems (LCMSs) to keep track of where students are in terms
of what language competencies they have mastered and the competencies they need
to get where they want to go. These competencies are based on the Common
European Framework for (English) Language Learning. This data can be available
for everyone involved with a given student's progress (e.g. educators, parents,
supervisors and the students themselves). A given student's record of past
accomplishments can also be meshed with those of his classmates. Not only are a
student's competencies easily seen and tracked, educators can view competencies
of a group of students that were achieved prior to enrollment in the class.
This should make curriculum decision making easier and more efficient for
educators.


title: Violation of detailed balance accelerates relaxation

abstract:
  Recent studies have experienced the acceleration of convergence in Markov
chain Monte Carlo methods implemented by the systems without detailed balance
condition (DBC). However, such advantage of the violation of DBC has not been
confirmed in general. We investigate the effect of the absence of DBC on the
convergence toward equilibrium. Surprisingly, it is shown that the DBC
violation always makes the relaxation faster. Our result implies the existence
of a kind of thermodynamic inequality that connects the nonequilibrium process
relaxing toward steady state with the relaxation process which has the same
probability distribution as its equilibrium state.


title:
Lattice Points in Orthotopes and a Huge Polynomial Tutte Invariant of
  Weighted Gain Graphs

abstract:
  A gain graph is a graph whose edges are orientably labelled from a group. A
weighted gain graph is a gain graph with vertex weights from an abelian
semigroup, where the gain group is lattice ordered and acts on the weight
semigroup. For weighted gain graphs we establish basic properties and we
present general dichromatic and forest-expansion polynomials that are Tutte
invariants (they satisfy Tutte's deletion-contraction and multiplicative
identities). Our dichromatic polynomial includes the classical graph one by
Tutte, Zaslavsky's two for gain graphs, Noble and Welsh's for graphs with
positive integer weights, and that of rooted integral gain graphs by Forge and
Zaslavsky. It is not a universal Tutte invariant of weighted gain graphs; that
remains to be found.
  An evaluation of one example of our polynomial counts proper list colorations
of the gain graph from a color set with a gain-group action. When the gain
group is Z^d, the lists are order ideals in the integer lattice Z^d, and there
are specified upper bounds on the colors, then there is a formula for the
number of bounded proper colorations that is a piecewise polynomial function of
the upper bounds, of degree nd where n is the order of the graph.
  This example leads to graph-theoretical formulas for the number of integer
lattice points in an orthotope but outside a finite number of affinographic
hyperplanes, and for the number of n x d integral matrices that lie between two
specified matrices but not in any of certain subspaces defined by simple row
equations.


title: Dynamic Computing Random Access Memory

abstract:
  The present von Neumann computing paradigm involves a significant amount of
information transfer between a central processing unit (CPU) and memory, with
concomitant limitations in the actual execution speed. However, it has been
recently argued that a different form of computation, dubbed memcomputing
[Nature Physics, 9, 200-202 (2013)] and inspired by the operation of our brain,
can resolve the intrinsic limitations of present day architectures by allowing
for computing and storing of information on the same physical platform. Here we
show a simple and practical realization of memcomputing that utilizes
easy-to-build memcapacitive systems. We name this architecture Dynamic
Computing Random Access Memory (DCRAM). We show that DCRAM provides
massively-parallel and polymorphic digital logic, namely it allows for
different logic operations with the same architecture, by varying only the
control signals. In addition, by taking into account realistic parameters, its
energy expenditures can be as low as a few fJ per operation. DCRAM is fully
compatible with CMOS technology, can be realized with current fabrication
facilities, and therefore can really serve as an alternative to the present
computing technology.


title:
Experimental Demonstration of Polarization Encoding
  Measurement-Device-Independent Quantum Key Distribution

abstract:
  We demonstrate the first implementation of polarization encoding
measurement-device-independent quantum key distribution (MDI-QKD), which is
immune to all detector side-channel attacks. Active phase randomization of each
individual pulse is implemented to protect against attacks on imperfect
sources. By optimizing the parameters in the decoy state protocol, we show that
it is feasible to implement polarization encoding MDI-QKD over large optical
fiber distances. A 1600-bit secure key is generated between two parties
separated by 10 km of telecom fibers. Our work suggests the possibility of
building a MDI-QKD network, in which complicated and expensive detection system
is placed in a central node and users connected to it can perform confidential
communication by preparing polarization qubits with compact and low-cost
equipment. Since MDI-QKD is highly compatible with the quantum network, our
work brings the realization of quantum internet one step closer.