title:
Fast-evolving weather for the coolest of our two new substellar
  neighbours

abstract:
  We present the results of an intense photometric monitoring in the
near-infrared (~0.9 microns) with the TRAPPIST robotic telescope of the newly
discovered binary brown dwarf WISE J104915.57-531906.1, the third closest
system to the Sun at a distance of only 2 pc. Our twelve nights of photometric
time-series reveal a quasi-periodic (P = 4.87+-0.01 h) variability with a
maximal peak-peak amplitude of ~11% and strong night-to-night evolution. We
attribute this variability to the rotational modulation of fast-evolving
weather patterns in the atmosphere of the coolest component (~T1-type) of the
binary, in agreement with the cloud fragmentation mechanism proposed to drive
the spectroscopic morphologies of brown dwarfs at the L/T transition. No
periodic signal is detected for the hottest component (~L8-type). For both
brown dwarfs, our data allow us to firmly discard any unique transit during our
observations for planets >= 2 Rearth. For orbital periods smaller than ~9.5 h,
transiting planets are excluded down to an Earth-size.


title:
Finitistic dimensions and piecewise hereditary property of skew group
  algebras

abstract:
  Let $\Lambda$ be a finite dimensional algebra and $G$ be a finite group whose
elements act on $\Lambda$ as algebra automorphisms. Under the assumption that
$\Lambda$ has a complete set $E$ of primitive orthogonal idempotents, closed
under the action of a Sylow $p$-subgroup $S \leqslant G$. If the action of $S$
on $E$ is free, we show that the skew group algebra $\Lambda G$ and $\Lambda$
have the same finitistic dimension, and have the same strong global dimension
if the fixed algebra $\Lambda^S$ is a direct summand of the
$\Lambda^S$-bimodule $\Lambda$. Using a homological characterization of
piecewise hereditary algebras proved by Happel and Zacharia, we deduce a
criterion for $\Lambda G$ to be piecewise hereditary.


title:
The nucleon mass and pion-nucleon sigma term from a chiral analysis of
  lattice QCD world data

abstract:
  The pion-mass dependence of the nucleon mass within the covariant SU(2)
baryon chiral perturbation theory both without and with explicit Delta(1232)
degrees of freedom up to order p^4 is investigated. By fitting to lattice QCD
data in 2 and 2+1 flavors from several collaborations, for pion masses M_pi <
420 MeV, we obtain low energy constants of natural size and compatible with
pion nucleon scattering data. Our results are consistent with the rather linear
pion-mass dependence showed by lattice QCD. In the 2 flavor case we have also
performed simultaneous fits to the nucleon mass and pion-nucleon sigma-term
data. As a result of our analysis, which encompasses the study of finite volume
corrections and discretization effects, we report a value for the pion-nucleon
sigma-term of 41(5)(4) MeV in the 2 flavor case and 52(3)(8) MeV for 2+1
flavors, where the inclusion of the Delta(1232) resonance changes the results
by around 9 MeV. In the 2 flavor case we are able to set independently the
scale for lQCD data, given by a Sommer scale of r_0=0.493(23) fm.


title: On the cosmology of massive gravity

abstract:
  We present a review of cosmological solutions in non-linear massive gravity,
focusing on the stability of perturbations. Although homogeneous and isotropic
solutions have been found, these are now known to suffer from either Higuchi
ghost or a new non-linear ghost instability. We discuss two approaches to
alleviate this issue. By relaxing the symmetry of the background by e.g.
breaking isotropy in the hidden sector, it is possible to accommodate a stable
cosmological solution. Alternatively, extending the theory to allow for new
dynamical degrees of freedom can also remove the conditions which lead to the
instability. As examples for this case, we study the stability of
self-accelerating solutions in the quasi-dilatonic extension and generic
cosmological solutions in the varying mass extension. While the quasi-dilaton
case turns out to be unstable, the varying mass case allows stable regimes of
parameters. Viable self-accelerating solutions in the varying mass theory yet
remain to be found.


title:
Multi-scale community organization of the human structural connectome
  and its relationship with resting-state functional connectivity

abstract:
  The human connectome has been widely studied over the past decade. A
principal finding is that it can be decomposed into communities of densely
interconnected brain regions. This result, however, may be limited
methodologically. Past studies have often used a flawed modularity measure in
order to infer the connectome's community structure. Also, these studies relied
on the intuition that community structure is best defined in terms of a
network's static topology as opposed to a more dynamical definition. In this
report we used the partition stability framework, which defines communities in
terms of a Markov process (random walk), to infer the connectome's multi-scale
community structure. Comparing the community structure to observed
resting-state functional connectivity revealed communities across a broad range
of dynamical scales that were closely related to functional connectivity. This
result suggests a mapping between communities in structural networks, models of
communication processes, and brain function. It further suggests that
communication in the brain is not limited to a single characteristic scale,
leading us to posit a heuristic for scale-selective communication in the
cerebral cortex.


title: Compactness of $\omega^\lambda$ for $\lambda$ singular

abstract:
  We characterize the compactness properties of the product of \lambda\ copies
of the space \omega\ with the discrete topology, dealing in particular with the
case \lambda\ singular, using regular and uniform ultrafilters, infinitary
languages and nonstandard elements. We also deal with products of uncountable
regular cardinals with the order topology.


title:
Rigidity of stationary black holes with small angular momentum on the
  horizon

abstract:
  We prove a black hole rigidity result for slowly rotating stationary
solutions of the Einstein vacuum equations. More precisely, we prove that the
domain of outer communications of a regular stationary vacuum is isometric to
the domain of outer communications of a Kerr solution, provided that the
stationary Killing vector-field $\T$ is small on the bifurcation sphere.


title: A note on the Duffin-Schaeffer conjecture

abstract:
  Given a sequence of real numbers $\{\psi(n)\}_{n\in\mathbb{N}}$ with $0\leq
\psi(n)<1$, let $W(\psi)$ denote the set of $x\in[0,1]$ for which
$|xn-m|<\psi(n)$ for infinitely many coprime pairs
$(n,m)\in\mathbb{N}\times\mathbb{Z}$. The purpose of this note is to show that
if there exists an $\epsilon>0$ such that
$\sum_{n\in\mathbb{N}}\psi(n)^{1+\epsilon}\cdot\frac{\varphi(n)}{n}=\infty,$
then the Lebesgue measure of $W(\psi)$ equals 1.


title: On the Mori-Szekely conjectures for the Borel-Cantelli lemma

abstract:
  The purpose of this note is to show by constructing counterexamples that two
conjectures of M\'{o}ri and Sz\'{e}kely for the Borel-Cantelli lemma are false.


title: Premiums And Reserves, Adjusted By Distortions

abstract:
  The net-premium principle is considered to be the most genuine and fair
premium principle in actuarial applications. However, an insurance company,
applying the net-premium principle, goes bankrupt with probability one in the
long run, even if the company covers its entire costs by collecting the
respective fees from its customers. It is therefore an intrinsic necessity for
the insurance industry to apply premium principles, which guarantee at least
further existence of the company itself; otherwise, the company naturally could
not insure its clients to cover their potential, future claims. Beside this
intriguing fact the underlying loss distribution typically is not known
precisely. Hence alternative premium principles have been developed. A simple
principle, ensuring risk-adjusted credibility premiums, is the distorted
premium principle. This principle is convenient in insurance companies, as the
actuary does not have to change his or her tools to compute the premiums or
reserves. This paper addresses the distorted premium principle from various
angles. First, dual characterizations are developed. Next, distorted premiums
are typically computed by under-weighting or ignoring low, but over-weighting
high losses. It is demonstrated here that there is an alternative, opposite
point of view, which consists in leaving the probability measure unchanged, but
increasing the outcomes instead. It turns out that this new point of view is
natural in actuarial practice, as it can be used for premium calculations, as
well as to determine the reserves of subsequent years in a time consistent way.


title: Polarized Charginos (and Tops) in Stop Decays

abstract:
  Current searches for direct production of scalar top quarks, or stops, in
supersymmetry focus on their decays into W boson + b quark + neutralino by way
of top + neutralino and bottom + chargino. While the polarization of the top
quark depends on the stop mixing, the chargino turns out to be fully polarized
when the bottom Yukawa coupling can be neglected relative the top Yukawa
coupling. We compute the energy and angular spectra of the charged lepton in
the chargino channel, which could serve as the spin-analyzer of the chargino.
In addition, we demonstrate the top polarization could have a significant
impact on the selection efficiencies in direct stop samples at the LHC, while
the effect from the chargino polarization is less pronounced. Two observables
in the laboratory frame, the opening angle between the charged lepton and the b
quark and the energy of the b quark, are also proposed to optimize searches in
the chargino channel versus the top channel.


title: The singular harmonic oscillator revisited

abstract:
  The one-dimensional Schr\"{o}dinger equation with the singular harmonic
oscillator is investigated. The Hermiticity of the operators related to
observable physical quantities is used as a criterion to show that the
attractive or repulsive singular oscillator exhibits an infinite number of
acceptable solutions provided the parameter responsible for the singularity is
greater than a certain critical value, in disagreement with the literature. The
problem for the whole line exhibits a two-fold degeneracy in the case of the
singular oscillator, and the intrusion of additional solutions in the case of a
nonsingular oscillator. Additionally, it is shown that the solution of the
singular oscillator can not be obtained from the nonsingular oscillator via
perturbation theory.


title: On the Jitter Radiation

abstract:
  In a small scale turbulent medium, when the nonrelativistic Larmor radius
$R_{\rm L}=mc^2/eB$ exceeds the correlation length $\lambda$ of the magnetic
field, the magnetic bremsstrahlung of charged relativistic particles
unavoidably proceeds in the so-called jitter radiation regime. The cooling
timescale of parent particles is identical to the synchrotron cooling time,
thus this radiation regime can be produced with very high efficiency in
different astrophysical sources characterized by high turbulence. The jitter
radiation has distinct spectral features shifted, compared to synchrotron
radiation, towards high energies. This makes the jitter mechanism an attractive
broad-band gamma-ray production channel which in highly magnetized and
turbulent environments can compete or even dominate over other high energy
radiation mechanisms. In this paper we present a novel study on spectral
properties of the jitter radiation performed within the framework of
perturbation theory. The derived general expression for the spectral power of
radiation is presented in a compact and convenient for numerical calculations
form.


title:
Algorithms for Routing an Unmanned Aerial Vehicle in the presence of
  Refueling Depots

abstract:
  We consider a single Unmanned Aerial Vehicle (UAV) routing problem where
there are multiple depots and the vehicle is allowed to refuel at any depot.
The objective of the problem is to find a path for the UAV such that each
target is visited at least once by the vehicle, the fuel constraint is never
violated along the path for the UAV, and the total fuel required by the UAV is
a minimum. We develop an approximation algorithm for the problem, and propose
fast construction and improvement heuristics to solve the same. Computational
results show that solutions whose costs are on an average within 1.4% of the
optimum can be obtained relatively fast for the problem involving 5 depots and
25 targets.


title:
Multifrequency study of SNR J0533-7202, a new supernova remnant in the
  LMC

abstract:
  We present a detailed study of Australia Telescope Compact Array (ATCA)
observations of a newly discovered Large Magellanic Cloud (LMC) supernova
remnant (SNR), SNR J0533-7202. This object follows a horseshoe morphology, with
a size 37 pc x 28 pc (1-pc uncertainty in each direction). It exhibits a radio
spectrum with the intrinsic synchrotron spectral index of alpha= -0.47+-0.06
between 73 and 6 cm. We report detections of regions showing moderately high
fractional polarisation at 6 cm, with a peak value of 36+-6% and a mean
fractional polarisation of 12+-7%. We also estimate an average rotation measure
across the remnant of -591 rad m^-2. The current lack of deep X-ray observation
precludes any conclusion about high-energy emission from the remnant. The
association with an old stellar population favours a thermonuclear supernova
origin of the remnant.


title: Barrow's Inequality and Signed Angle Bisectors

abstract:
  In this paper we give one extension of Barrow's type inequality in the plane
of the triangle ABC introduce signed angle bisectors.


title:
Wave theories of non-laminar charged particle beams: from quantum to
  thermal regime

abstract:
  The standard classical description of non-laminar charge particle beams in
paraxial approximation is extended to the context of two wave theories. The
first theory is the so-called Thermal Wave Model (TWM) that interprets the
paraxial thermal spreading of the beam particles as the analog of the quantum
diffraction. The other theory, hereafter called Quantum Wave Model (QWM), that
takes into account the individual quantum nature of the single beam particle
(uncertainty principle and spin) and provides the collective description of the
beam transport in the presence of the quantum paraxial diffraction. QWM can be
applied to beams that are sufficiently cold to allow the particles to manifest
their individual quantum nature but sufficiently warm to make overlapping-less
the single-particle wave functions. In both theories, the propagation of the
beam transport in plasmas or in vacuo is provided by fully similar set of
nonlinear and nonlocal governing equations, where in the case of TWM the
Compton wavelength (fundamental emittance) is replaced by the beam thermal
emittance. In both models, the beam transport in the presence of the
self-fields (space charge and inductive effects) is governed by a suitable
nonlinear nonlocal 2D Schroedinger equation that is used to obtain the envelope
beam equation in quantum and quantum-like regimes, respectively. An envelope
equation is derived for both TWM and QWM regimes. In TWM we recover the well
known Sacherer equation whilst, in QWM we obtain the evolution equation of the
single-particle spot size, i.e., single quantum ray spot in the transverse
plane (Compton regime). We show that such a quantum evolution equation contains
the same information carried out by an evolution equation for the beam spot
size (description of the beam as a whole). This is done by defining the lowest
QWM state reachable by a system of overlapping-less Fermions.


title: Automorphisms of free groups, I

abstract:
  We describe, up to degree equal to the rank, the Lie algebra associated with
the automorphism group of a free group. We compute in particular the ranks of
its homogeneous components, and their structure as modules over the linear
group.
  Along the way, we infirm (but confirm a weaker form of) a conjecture by
Andreadakis, and answer a question by Bryant-Gupta-Levin-Mochizuki.


title: Splitting Methods for Convex Clustering

abstract:
  Clustering is a fundamental problem in many scientific applications. Standard
methods such as $k$-means, Gaussian mixture models, and hierarchical
clustering, however, are beset by local minima, which are sometimes drastically
suboptimal. Recently introduced convex relaxations of $k$-means and
hierarchical clustering shrink cluster centroids toward one another and ensure
a unique global minimizer. In this work we present two splitting methods for
solving the convex clustering problem. The first is an instance of the
alternating direction method of multipliers (ADMM); the second is an instance
of the alternating minimization algorithm (AMA). In contrast to previously
considered algorithms, our ADMM and AMA formulations provide simple and unified
frameworks for solving the convex clustering problem under the previously
studied norms and open the door to potentially novel norms. We demonstrate the
performance of our algorithm on both simulated and real data examples. While
the differences between the two algorithms appear to be minor on the surface,
complexity analysis and numerical experiments show AMA to be significantly more
efficient.


title: Exploration of the local solar neighborhood I: Fixed number of probes

abstract:
  Previous work in studying interstellar exploration by one or several probes
has focused primarily either on engineering models for a spacecraft targeting a
single star system, or large-scale simulations to ascertain the time required
for a civilization to completely explore the Milky Way galaxy. In this paper, a
simulated annealing algorithm is used to numerically model the exploration of
the local interstellar neighborhood (i.e. on the order of ten parsecs of the
Solar System) by a fixed number of probes launched from the Solar System; these
simulations use the observed masses, positions and spectral classes of targeted
stars. Each probe visits a pre-determined list of target systems, maintains a
constant cruise speed, and only changes direction from gravitational deflection
at each target. From these simulations, it is examined how varying design
choices -- differing the maximum cruise speed, number of probes launched,
number of target stars to be explored, and probability of avoiding catastrophic
system failure per parsec -- change the completion time of the exploration
program and the expected number of stars successfully visited. In addition, it
is shown that improving this success probability per parsec has diminishing
returns beyond a certain point. Future improvements to the model and possible
implications are discussed.


title:
Equivalence for Rank-metric and Matrix Codes and Automorphism Groups of
  Gabidulin Codes

abstract:
  For a growing number of applications such as cellular, peer-to-peer, and
sensor networks, efficient error-free transmission of data through a network is
essential. Toward this end, K\"{o}tter and Kschischang propose the use of
subspace codes to provide error correction in the network coding context. The
primary construction for subspace codes is the lifting of rank-metric or matrix
codes, a process that preserves the structural and distance properties of the
underlying code. Thus, to characterize the structure and error-correcting
capability of these subspace codes, it is valuable to perform such a
characterization of the underlying rank-metric and matrix codes. This paper
lays a foundation for this analysis through a framework for classifying
rank-metric and matrix codes based on their structure and distance properties.
  To enable this classification, we extend work by Berger on equivalence for
rank-metric codes to define a notion of equivalence for matrix codes, and we
characterize the group structure of the collection of maps that preserve such
equivalence. We then compare the notions of equivalence for these two related
types of codes and show that matrix equivalence is strictly more general than
rank-metric equivalence. Finally, we characterize the set of equivalence maps
that fix the prominent class of rank-metric codes known as Gabidulin codes. In
particular, we give a complete characterization of the rank-metric automorphism
group of Gabidulin codes, correcting work by Berger, and give a partial
characterization of the matrix-automorphism group of the expanded matrix codes
that arise from Gabidulin codes.


title: Algebraic techniques in designing quantum synchronizable codes

abstract:
  Quantum synchronizable codes are quantum error-correcting codes that can
correct the effects of quantum noise as well as block synchronization errors.
We improve the previously known general framework for designing quantum
synchronizable codes through more extensive use of the theory of finite fields.
This makes it possible to widen the range of tolerable magnitude of block
synchronization errors while giving mathematical insight into the algebraic
mechanism of synchronization recovery. Also given are families of quantum
synchronizable codes based on punctured Reed-Muller codes and their ambient
spaces.


title:
Nonparametric likelihood based estimation of linear filters for point
  processes

abstract:
  We consider models for multivariate point processes where the intensity is
given nonparametrically in terms of functions in a reproducing kernel Hilbert
space. The likelihood function involves a time integral and is consequently not
given in terms of a finite number of kernel evaluations. The main result is a
representation of the gradient of the log-likelihood, which we use to derive
computable approximations of the log-likelihood and the gradient by time
discretization. These approximations are then used to minimize the approximate
penalized log-likelihood. For time and memory efficiency the implementation
relies crucially on the use of sparse matrices. As an illustration we consider
neuron network modeling, and we use this example to investigate how the
computational costs of the approximations depend on the resolution of the time
discretization. The implementation is available in the R package ppstat.


title: Distributing Entanglement with Separable States

abstract:
  Like a silver thread, quantum entanglement [1] runs through the foundations
and breakthrough applications of quantum information theory. It cannot arise
from local operations and classical communication (LOCC) and therefore
represents a more intimate relationship among physical systems than we may
encounter in the classical world. The `nonlocal' character of entanglement
manifests itself through a number of counterintuitive phenomena encompassing
Einstein-Podolsky-Rosen paradox [2,3], steering [4], Bell nonlocality [5] or
negativity of entropy [6,7]. Furthermore, it extends our abilities to process
information. Here, entanglement is used as a resource which needs to be shared
between several parties, eventually placed at remote locations. However
entanglement is not the only manifestation of quantum correlations. Notably,
also separable quantum states can be used as a shared resource for quantum
communication. The experiment presented in this paper highlights the
quantumness of correlations in separable mixed states and the role of classical
information in quantum communication by demonstrating entanglement distribution
using merely a separable ancilla mode.


title:
Broken relationship between superconducting pairing interaction and
  electronic dispersion kinks in LSCO

abstract:
  Electronic band dispersions in copper oxide superconductors have kinks around
70 meV that are typically attributed to coupling of electrons to a bosonic
mode. We performed angle resolved photoemission spectroscopy (ARPES)
experiments on overdoped cuprate high temperature superconductors to test the
relationship between the superconducting transition temperature and
electron-bosonic mode coupling. Remarkably, the kinks remain strong in the
heavily overdoped region of the doping phase diagram of LSCO, even when the
superconductivity completely disappears. This unexpected observation is
incompatible with the conventional picture of superconductivity mediated by the
sharp bosonic modes that are responsible for the kink. Therefore, the pairing
likely originates from something else, such as from interactions with a very
broad electronic spectrum or from an unconventional mechanism without pairing
glue.


title: An exact formalism for the quench dynamics of integrable models

abstract:
  We describe a formulation for studying the quench dynamics of integrable
systems generalizing an approach by Yudson. We study the evolution of the
Lieb-Liniger model, a gas of interacting bosons moving on the continuous
infinite line and interacting via a short range potential. The formalism allows
us to quench the system from any initial state. We find that for any value of
repulsive coupling independently of the initial state the system asymptotes
towards a strongly repulsive gas, while for any value of attractive coupling,
the system forms a maximal bound state that dominates at longer times. In
either case the system equilibrates but does not thermalize. We compare this to
quenches in a Bose-Hubbard lattice and show that there, initial states
determine long-time dynamics independent of the sign of the coupling.


title: Charge-Focusing Readout of Time Projection Chambers

abstract:
  Time projection chambers (TPCs) have found a wide range of applications in
particle physics, nuclear physics, and homeland security. For TPCs with
high-resolution readout, the readout electronics often dominate the price of
the final detector. We have developed a novel method which could be used to
build large-scale detectors while limiting the necessary readout area. By
focusing the drift charge with static electric fields, we would allow a small
area of electronics to be sensitive to particle detection for a much larger
detector volume. The resulting cost reduction could be important in areas of
research which demand large-scale detectors, including dark matter searches and
detection of special nuclear material. We present simulations made using the
software package Garfield of a focusing structure to be used with a prototype
TPC with pixel readout. This design should enable significant focusing while
retaining directional sensitivity to incoming particles. We also present first
experimental results and compare them with simulation.


title:
Computational Complexity and the Interpretation of a Quantum State
  Vector

abstract:
  The macro-objectivation problem derives from the fact that the Schrodinger
equation is linear and thus requires that a macroscopic system interacting with
an entangled state must be entangled as well. However, such a requirement
entails that the Schrodinger equation must also be solvable in the macroscopic
world in the same way as it is solvable in the microscopic world, which itself
is an assumption. In this work, the alternative assumption that the Schrodinger
equation is in general an intractable problem is considered.


title: Photon Aided and Inhibited Tunneling of Photons

abstract:
  In the light of the interest in the transport of single photons in arrays of
waveguides, fiber couplers, photonic crystals, etc., we consider the quantum
mechanical process of the tunneling of photons through evanescently or
otherwise coupled structures. We specifically examine the issue of tunneling
between two structures when one structure already contains few photons. We
demonstrate the possibility of both photon aided and inhibited tunneling of
photons. The Bosonic nature of photons enhances the tunneling probability. We
also show how the multiphoton tunneling probability can be either enhanced or
inhibited due to the presence of photons. We find similar results for the
higher order tunneling. Finally, we show that the presence of a squeezed field
changes the nature of tunneling considerably.


title: Simulation of the Majorana equation in circuit QED

abstract:
  We propose a scheme to simulate the 1D Majorana equation with two Cooper pair
boxes coupled to a 1D superconducting transmission line resonator, where strong
coupling limit can be achieved. With proper chosen of systematic parameters, we
are able to engineer different kinds of interaction, which is indispensable in
simulating the Majorana equation in an enlarged real Hilbert space. Measurement
of the conserved observable of pseudo-helicity via transmission spectrum of the
cavity field can verify the simulated Majorana wave function. The measurement
results are experimentally resolvable based on our estimation with conservative
parameters.


title: Diffractive Effects and General Boundary Conditions in Casimir Energy

abstract:
  The effect of edges and apertures on the Casimir energy of an arrangement of
plates and boundaries can be calculated in terms of an effective nonlocal
lower-dimensional field theory that lives on the boundary. This formalism has
been developed in a number of previous papers and applied to specific examples
with Dirichlet boundary conditions. Here we generalize the formalism to
arbitrary boundary conditions. As a specific example, the geometry of a flat
plate and a half-plate placed parallel to it is considered for a number of
different boundary conditions and the area-dependent and edge dependent
contributions to the Casimir energy are evaluated. While our results agree with
known results for those special cases (such as the Dirichlet and Neumann
limits) for which other methods of calculation have been used, our formalism is
suitable for general boundary conditions, especially for the diffractive
effects.


title: Cu NQR and NMR Studies of Optimally Doped Ca2-xNaxCuO2Cl2

abstract:
  We report on Cu nuclear quadrupole resonance (NQR) and NMR studies of an
optimally hole-doped superconductor Ca2-xNaxCuO2Cl2 (Tc ~ 28 K for x ~ 0.2). In
spite of robust oxygen composition, we observed a multiple broad NQR frequency
spectrum and nonexponential Cu nuclear spin-lattice relaxation, being similar
to those of La2-xSrxCuO4-d.


title: Separating OR, SUM, and XOR Circuits

abstract:
  Given a boolean n by n matrix A we consider arithmetic circuits for computing
the transformation x->Ax over different semirings. Namely, we study three
circuit models: monotone OR-circuits, monotone SUM-circuits (addition of
non-negative integers), and non-monotone XOR-circuits (addition modulo 2). Our
focus is on \emph{separating} these models in terms of their circuit
complexities. We give three results towards this goal:
  (1) We prove a direct sum type theorem on the monotone complexity of tensor
product matrices. As a corollary, we obtain matrices that admit OR-circuits of
size O(n), but require SUM-circuits of size \Omega(n^{3/2}/\log^2n).
  (2) We construct so-called \emph{k-uniform} matrices that admit XOR-circuits
of size O(n), but require OR-circuits of size \Omega(n^2/\log^2n).
  (3) We consider the task of \emph{rewriting} a given OR-circuit as a
XOR-circuit and prove that any subquadratic-time algorithm for this task
violates the strong exponential time hypothesis.


title: Je\'{s}manowicz' conjecture and Fermat numbers

abstract:
  Let $a,b,c$ be relatively prime positive integers such that
$a^{2}+b^{2}=c^{2}.$ In 1956, Je\'{s}manowicz conjectured that for any positive
integer $n$, the only solution of $(an)^{x}+(bn)^{y}=(cn)^{z}$ in positive
integers is $(x,y,z)=(2,2,2)$. Let $k\geq 1$ be an integer and $F_k=2^{2^k}+1$
be a Fermat number. In this paper, we show that Je\'{s}manowicz' conjecture is
true for Pythagorean triples $(a,b,c)=(F_k-2,2^{2^{k-1}+1},F_k)$.


title:
Survey of Exciton-Phonon Sidebands by Magneto-optical Spectroscopy Using
  Highly Purified (6,5) Single-walled Carbon Nanotubes

abstract:
  We report the first high-field magneto-optical study on the exciton-phonon
sideband of single-walled carbon nanotubes (SWNTs) consisting only of (6,5)
species. Both energy and intensity of the observed phonon sideband were found
to be independent of the external magnetic field. Comparing with theoretical
calculations, we confirmed that these sidebands originate from the optically
forbidden K-momentum singlet excitons. Energy of these K-momentum dark excitons
was extracted to be ~ 21.5 meV above the bright zero-momentum singlet excitons,
in close agreement with recent theoretical predictions and experimentally
determined values.


title: Unusual Brownian motion of photons in open absorbing media

abstract:
  Very recent experiments have discovered that localized light in strongly
absorbing media displays intriguing diffusive phenomena. Here we develop a
first-principles theory of light propagation in open media with arbitrary
absorption strength and sample length. We show analytically that photons in
localized open absorbing media exhibit unusual Brownian motion. Specifically,
wave transport follows the diffusion equation with the diffusion coefficient
exhibiting spatial resolution. Most strikingly, despite that the system is
controlled by two parameters -- the ratio of the localization (absorption)
length to the sample length -- the spatially resolved diffusion coefficient
displays novel single parameter scaling: it depends on the space via the
returning probability. Our analytic predictions for this diffusion coefficient
are confirmed by numerical simulations. In the strong absorption limit they
agree well with the experimental results.


title: Constraints on dark matter annihilation by radio observations of M31

abstract:
  We used radio observations of the neighbour galaxy M31 in order to put
constraints on dark matter particle mass and annihilation cross section. Dark
matter annihilation in M31 halo produces highly energetic leptons, which emit
synchrotron radiation on radio frequencies in the galactic magnetic field. We
predicted expected radio fluxes for the two annihilation channels: \chi\chi ->
bb* and \chi\chi -> \tau^+\tau^-. We then compared them with available data on
the central radio emission of M31 as observed by four radio surveys: VLSS (74
MHz), WENSS (325 MHz), NVSS (1400 MHz) and GB6 (4850 MHz). Assuming a standard
NFW dark matter density profile and a conservative magnetic field distribution
inside the Andromeda galaxy, we find that the thermal relic annihilation cross
section <\sigma v> = 3*10^{-26} cm^3/s or higher are only allowed for WIMP
masses greater than 100 GeV and 55 GeV for annihilation into bb* and
\tau^+\tau^- respectively. Taking into account potential uncertainties in the
distributions of DM density and magnetic field, the mentioned WIMP limiting
masses can be as low as 23 GeV for both channels, and as high as 280 and 130
GeV for annihilation into bb* and \tau^+\tau^- respectively. These mass values
exceed the best up-to-day known constraints from Fermi gamma observations: 40
GeV and 19 GeV respectively [A.Geringer-Sameth and S.M.Koushiappas, Phys. Rev.
Lett. 107, 241303 (2011)]. Precise measurements of the magnetic field in the
relevant region and better reconstruction of the DM density profile of M31 will
be able to reduce the uncertainties of our exclusion limits.


title: Outers for noncommutative H^p revisited

abstract:
  We continue our study of outer elements of the noncommutative H^p spaces
associated with Arveson's subdiagonal algebras. We extend our generalized
inner-outer factorization theorem, and our characterization of outer elements,
to include the case of elements with zero determinant. In addition, we make
several further contributions to the theory of outers. For example, we
generalize the classical fact that outers in H^p actually satisfy the stronger
condition that there exist a_n in A with h a_n in Ball(A) and h a_n \to 1 in
p-norm.


title:
Singular Density of States Measure for Subshift and Quasi-Periodic
  Schr\"odinger Operators

abstract:
  Simon's subshift conjecture states that for every aperiodic minimal subshift
of Verblunsky coefficients, the common essential support of the associated
measures has zero Lebesgue measure. We disprove this conjecture in this paper,
both in the form stated and in the analogous formulation of it for discrete
Schr\"odinger operators. In addition we prove a weak version of the conjecture
in the Schr\"odinger setting. Namely, under some additional assumptions on the
subshift, we show that the density of states measure, a natural measure
associated with the operator family and whose topological support is equal to
the spectrum, is singular. We also consider one-frequency quasi-periodic
Schr\"odinger operators with continuous sampling functions and show that
generically, the density of states measure is singular as well.


title: Parametrized K-Theory

abstract:
  In nature, one observes that a K-theory of an object is defined in two steps.
First a "structured" category is associated to the object. Second, a K-theory
machine is applied to the latter category to produce an infinite loop space. We
develop a general framework that deals with the first step of this process. The
K-theory of an object is defined via a category of "locally trivial" objects
with respect to a pretopology. We study conditions ensuring an exact structure
on such categories. We also consider morphisms in K-theory that such contexts
naturally provide. We end by defining various K-theories of schemes and
morphisms between them.


title:
The Number of Irreducible Polynomials over Finite Fields of
  Characteristic 2 with Given Trace and Subtrace

abstract:
  In this paper we obtained the formula for the number of irreducible
polynomials with degree $n$ over finite fields of characteristic two with given
trace and subtrace. This formula is a generalization of the result of Cattell
et al.(2003) [2].


title: Preliminary Study on the RF tuning of CSNS DTL

abstract:
  In the R&D of the CSNS Drift Tube Linac (DTL), the first unit tank with 28
drift tubes has been developed. The axial accelerating field is ramped from
2.2MV/m to 3.1MV/m in this tank. The required field flatness is less than 2 %
with the standard deviation of 1 % for the beam dynamics. And the field
stability should be less than 1% for machine stable operation. After the
successful alignment, the RF tuning was carried out focusing on the field
profile measurement. Four slug tuners and 11 post couplers were applied in this
procedure. The ramped filed and required stability had been achieved by fine
adjustment of the slug tuners and post couplers. In this paper, the preliminary
tuning results are presented and discussed.


title: Magnesium Isotope Ratios in omega Centauri Red Giants

abstract:
  We have used high resolution observations obtained at the AAT with UHRF (R ~
100,000) and at Gemini-S with b-HROS (R ~ 150,000) to determine magnesium
isotope ratios for seven omega Centauri red giants that cover a range in iron
abundance from [Fe/H] = --1.78 to --0.78 dex, and for two red giants in M4 (NGC
6121). The omega Centauri stars sample both the "primordial" (i.e., O-rich, Na
and Al-poor) and the "extreme" (O-depleted, Na and Al-rich) populations in the
cluster. The primordial population stars in both omega Centauri and M4 show
(25Mg, 26Mg)/24 Mg isotopic ratios that are consistent with those found for the
primordial population in other globular clusters with similar [Fe/H] values.
The isotopic ratios for the omega Centauri extreme stars are also consistent
with those for extreme population stars in other clusters. The results for the
extreme population stars studied indicate that the 26Mg/24Mg ratio is highest
at intermediate metallicities ([Fe/H] < --1.4 dex), and for the highest [Al/Fe]
values. Further, the relative abundance of 26Mg in the extreme population stars
is notably higher than that of 25Mg, in contrast to model predictions. The
25Mg/24Mg isotopic ratio in fact does not show any obvious dependence on either
[Fe/H] or [Al/Fe] nor, intriguingly, any obvious difference between the
primordial and extreme population stars.


title: A Fast Algorithm for Well-Spaced Points and Approximate Delaunay Graphs

abstract:
  We present a new algorithm that produces a well-spaced superset of points
conforming to a given input set in any dimension with guaranteed optimal output
size. We also provide an approximate Delaunay graph on the output points. Our
algorithm runs in expected time $O(2^{O(d)}(n\log n + m))$, where $n$ is the
input size, $m$ is the output point set size, and $d$ is the ambient dimension.
The constants only depend on the desired element quality bounds.
  To gain this new efficiency, the algorithm approximately maintains the
Voronoi diagram of the current set of points by storing a superset of the
Delaunay neighbors of each point. By retaining quality of the Voronoi diagram
and avoiding the storage of the full Voronoi diagram, a simple exponential
dependence on $d$ is obtained in the running time. Thus, if one only wants the
approximate neighbors structure of a refined Delaunay mesh conforming to a set
of input points, the algorithm will return a size $2^{O(d)}m$ graph in
$2^{O(d)}(n\log n + m)$ expected time. If $m$ is superlinear in $n$, then we
can produce a hierarchically well-spaced superset of size $2^{O(d)}n$ in
$2^{O(d)}n\log n$ expected time.


title:
The quark-jet contribution to the fragmentation functions for the pion
  and kaon with the nonlocal interactions

abstract:
  We investigate the unpolarized pion and kaon fragmentation functions using
the nonlocal chiral-quark model. In this model the interactions between the
quarks and pseudoscalar mesons is manifested nonlocally. In addition, the
explicit flavor SU(3) symmetry breaking effect is taken into account in terms
of the current quark masses. The results of our model are evaluated to higher
$Q^2$ value $Q^2=4\,\mathrm{GeV}^2$ by the DGLAP evolution. Then we compare
them with the empirical parametrizations. We find that our results are in
relatively good agreement with the empirical parametrizations and the other
theoretical estimations.


title: ON the Nature of the Local Spiral Arm of the Milky Way

abstract:
  Trigonometric parallax measurements of nine water masers associated with the
Local arm of the Milky Way were carried out as part of the BeSSeL Survey using
the VLBA. When combined with 21 other parallax measurements from the
literature, the data allow us to study the distribution and 3-dimensional
motions of star forming regions in the spiral arm over the entire northern sky.
Our results suggest that the Local arm does not have the large pitch angle
characteristic of a short spur. Instead its active star formation, overall
length (>5 kpc), and shallow pitch angle (~10 degrees) suggest that it is more
like the adjacent Perseus and Sagittarius arms; perhaps it is a branch of one
of these arms. Contrary to previous results, we find the Local arm to be closer
to the Perseus than to the Sagittarius arm, suggesting that a branching from
the former may be more likely. An average peculiar motion of near-zero toward
both the Galactic center and north Galactic pole, and counter rotation of ~ 5
km/s were observed, indicating that the Local arm has similar kinematic
properties as found for other major spiral arms.


title:
The cup product on Hochschild cohomology via twisting cochains and
  applications to Koszul rings

abstract:
  Given an acyclic twisting cochain $\pi:C\to A$, from a curved dg coalgebra
$C$ to a dg algebra $A$, we show that the associated twisted hom complex
$\mathrm{Hom}^\pi_k(C,A)$ has cohomology equal to the Hochschild cohomology of
$A$, as a graded ring. As a corollary we find that the Hochschild cohomology of
a Koszul algebra $A$, along with its cup product, is a subquotient of the
tensor product algebra $A^!\otimes A$ of $A$ with its Koszul dual.


title: Efficient repeat finding via suffix arrays

abstract:
  We solve the problem of finding interspersed maximal repeats using a suffix
array construction. As it is well known, all the functionality of suffix trees
can be handled by suffix arrays, gaining practicality. Our solution improves
the suffix tree based approaches for the repeat finding problem, being
particularly well suited for very large inputs. We prove the corrrectness and
complexity of the algorithms.


title:
Asymptotic spectrum of the oblate spin-weighted spheroidal harmonics: a
  WKB analysis

abstract:
  Spin-weighted spheroidal harmonics play a central role in the mathematical
description of diverse physical phenomena, including black-hole perturbation
theory and wave scattering. We present a novel and compact derivation of the
asymptotic eigenvalues of these important functions. Our analysis is based on a
simple trick which transforms the corresponding spin-weighted spheroidal
angular equation into a Schr\"odinger-like wave equation which is amenable to a
standard WKB analysis.

categories: gr-qc astro-ph.HE hep-th math-ph math.MP


title: The Ring of Algebraic Functions on Persistence Bar Codes

abstract:
  We study the ring of algebraic functions on the space of persistence
barcodes, with applications to pattern recognition.


title: Algebraic supergroups and Harish-Chandra pairs over a commutative ring

abstract:
  We prove a category equivalence between algebraic supergroups and
Harish-Chandra pairs over a commutative ring which is $2$-torsion free. The
result is applied to re-construct the Chevalley $\mathbb{Z}$-supergroups
constructed by Fioresi and Gavarini [8] and by Gavarini [9, 10]. For a wide
class of algebraic supergroups we describe their representations by using their
super-hyperalgebras.


title:
Strong constraints on models that explain the violation of Bell
  inequalities with hidden superluminal influences

abstract:
  We discuss models that attempt to provide an explanation for the violation of
Bell inequalities at a distance in terms of hidden influences. These models
reproduce the quantum correlations in most situations, but are restricted to
produce local correlations in some configurations. The argument presented in
[Bancal et al. Nature Physics 8, 867 (2012)] applies to all of these models,
which can thus be proved to allow for faster-than-light communication. In other
words, the signalling character of these models cannot remain hidden.


title: Energy-momentum tensor from the Yang-Mills gradient flow

abstract:
  The product of gauge fields generated by the Yang-Mills gradient flow for
positive flow times does not exhibit the coincidence-point singularity and a
local product is thus independent of the regularization. Such a local product
can furthermore be expanded by renormalized local operators at zero flow time
with finite coefficients that are governed by renormalization group equations.
Using these facts, we derive a formula that relates the small flow-time
behavior of certain gauge-invariant local products and the correctly-normalized
conserved energy-momentum tensor in the Yang-Mills theory. Our formula provides
a possible method to compute the correlation functions of a well-defined
energy-momentum tensor by using lattice regularization and Monte Carlo
simulation.


title:
Numerical solution of one-dimensional Sine--Gordon equation using
  Reproducing Kernel Hilbert Space Method

abstract:
  In this paper, we propose a reproducing kernel Hilbert space method (RKHSM)
for solving the sine--Gordon (SG) equation with initial and boundary conditions
based on the reproducing kernel theory. Its exact solution is represented in
the form of series in the reproducing kernel Hilbert space. Some numerical
examples have been studied to demonstrate the accuracy of the present method.
The results obtained from the method are compared with the exact solutions and
the earlier works. Results of numerical examples show that the presented method
is simple and effective.


title: Ordering and phonons in Ba$_3$CaNb$_{2}$O$_9$ complex perovskite

abstract:
  In this work we performed a detailed investigation about ordering in \bcn
perovskite. The sintering temperature and time were changed to obtain samples
with different ordering. The order parameters were probed by Raman spectroscopy
based on a partial disordered model. To use the partial disordered model
correctly we performed {\it ab initio} calculations in \bcn to assign the
optical phonons. The results showed that sintering temperature improves order
while sintering time is not so efficient to promote order.


title:
On the topology of the complements of reducible plane curves via Galois
  covers

abstract:
  Let ${\mathcal {B}}$ be a reducible reduced plane curve. We introduce a new
point of view to study the topology of $(\PP^2, {\mathcal {B}})$ via Galois
covers and Alexander polynomials. We show its effectiveness through examples of
Zariski $N$-plets for conic and conic-quartic configurations.


title: Dual To Ratio Cum Product Estimator In Stratified Random Sampling

abstract:
  Tracy et al.[8] have introduced a family of estimators using Srivenkataramana
and Tracy ([6],[7]) transformation in simple random sampling. In this article,
we have proposed a dual to ratio-cum-product estimator in stratified random
sampling. The expressions of the mean square error of the proposed estimators
are derived. Also, the theoretical findings are supported by a numerical
example.


title: OESPA:A Theory of Programming that Support Software Engineering

abstract:
  A new theory of programming is proposed. The theory consists of OE (Operation
Expression), SP (Semantic Predicate) and A (Axiom), abbreviated as OESPA. OE is
for programming: its syntax is given by BNF formulas and its semantics is
defined by axioms on these formulas. Similar to predicates in logic, SP is for
describing properties of OE (i.e. programs) and for program property analysis.
But SP is different from predicates, it directly relates the final values of
variables upon termination of a given OE with initial values of these variables
before the same OE. As such, it is feasible to prove or disprove whether a
given SP is a property of a given OE by computation based on A (Axioms). SP
calculus is proposed for program specification and specification analysis, that
is missing in software engineering.


title:
A Real-time Group Auction System for Efficient Allocation of Cloud
  Internet Applications

abstract:
  Increasing number of the cloud-based Internet applications demands for
efficient resource and cost management. This paper proposes a real-time group
auction system for the cloud instance market. The system is designed based on a
combinatorial double auction, and its applicability and effectiveness are
evaluated in terms of resource efficiency and monetary benefits to auction
participants (e.g., cloud users and providers). The proposed auction system
assists them to decide when and how providers allocate their resources to which
users. Furthermore, we propose a distributed algorithm using a group formation
game that determines which users and providers will trade resources by their
cooperative decisions. To find how to allocate the resources, the utility
optimization problem is formulated as a binary integer programming problem, and
the nearly optimal solution is obtained by a heuristic algorithm with quadratic
time complexity. In comparison studies, the proposed real-time group auction
system with cooperation outperforms an individual auction in terms of the
resource efficiency (e.g., the request acceptance rate for users and resource
utilization for providers) and monetary benefits (e.g., average payments for
users and total profits for providers).


title:
An example of circle actions on symplectic Calabi-Yau manifolds with
  non-empty fixed points

abstract:
  Let $(X,\sigma,J)$ be a compact K\"{a}hler Calabi-Yau manifold equipped with
a symplectic circle action. By Frankel's theorem \cite{F}, the action on $X$ is
non-Hamiltonian and $X$ does not have any fixed point. In this paper, we will
show that a symplectic circle action on a compact non-K\"{a}hler symplectic
Calabi-Yau manifold may have a fixed point. More precisely, we will show that
the symplectic $S^1$-manifold constructed by D. McDuff \cite{McD} has the
vanishing first Chern class. This manifold has the Betti numbers $b_1 = 3$,
$b_2 = 8$, and $b_3 = 12$. In particular, it does not admit any K\"{a}hler
structure.


title:
On generalization of the Freudental's theorem for compact irreducible
  standard polyhedric representation for superparacompact complete metrizable
  spaces

abstract:
  In this paper for superparacompact complete metrizable spaces the
Freudenthal's theorem for compact irreducible standard polyhedric
representation is generalized. Furthermore, for superparacompact metric spaces
are reinforced: 1) the Morita's theorem about universality of the product
$Q^\infty\times B(\tau)$ of Hilbert cube $Q^\infty$ to generalized Baire space
$B(\tau)$ of the weight $\tau$ in the space of all strongly metrizable spaces
of weight $\le \tau$; 2) the Nagata's theorem about universality of the product
$\Phi^n\times B(\tau)$ of universal $n$- dimensional compact $\Phi^n$ to
$B(\tau)$ in the space of all strongly metrizable spaces $\le\tau$ and
dimension $dimX\le n.$


title:
Multichannel Electrophysiological Spike Sorting via Joint Dictionary
  Learning & Mixture Modeling

abstract:
  We propose a construction for joint feature learning and clustering of
multichannel extracellular electrophysiological data across multiple recording
periods for action potential detection and discrimination ("spike sorting").
Our construction improves over the previous state-of-the art principally in
four ways. First, via sharing information across channels, we can better
distinguish between single-unit spikes and artifacts. Second, our proposed
"focused mixture model" (FMM) elegantly deals with units appearing,
disappearing, or reappearing over multiple recording days, an important
consideration for any chronic experiment. Third, by jointly learning features
and clusters, we improve performance over previous attempts that proceeded via
a two-stage ("frequentist") learning process. Fourth, by directly modeling
spike rate, we improve detection of sparsely spiking neurons. Moreover, our
Bayesian construction seamlessly handles missing data. We present
state-of-the-art performance without requiring manually tuning of many
hyper-parameters on both a public dataset with partial ground truth and a new
experimental dataset.


title: Seven Pulsars in Binary Systems above the Spin-up Line

abstract:
  Using data from the ATNF pulsar catalogue, 186 binary pulsars are shown in
the magnetic field versus spin period (B-P) diagram, and their relationship to
the spin-up line is investigated. Generally speaking, pulsars in binary systems
should be below the spin-up line when they get enough accretion mass from their
companions. It is found that there are seven binary pulsars above the spin-up
line. Based on the parameters of these seven binary systems, we describe
possible reasons why they are above the spin-up line.


title:
Symplectic spinor valued forms and invariant operators acting between
  them

abstract:
  Exterior differential forms with values in the (Kostant's) symplectic spinor
bundle on a manifold with a given metaplectic structure are decomposed into
invariant subspaces. Projections to these invariant subspaces of a covariant
derivative associated to a torsion-free symplectic connection are described.


title: Quantum particles passing through a matter-wave aperture

abstract:
  We investigate theoretically a dilute stream of free quantum particles
passing through a macroscopic circular aperture of matter-waves and then moving
in a space at a finite temperature, taking into account the dissipative
coupling with the environment. The portion of particles captured by the
detection screen is studied by varying the distance between the aperture and
the screen. Depending on the wavelength, the temperature, and the dimension of
the aperture, an unusual local valley-peak structure is found in increasing the
distance, in contrast to traditional thinking that it decreases monotonically.
The underlying mechanism is the nonlocality in the process of decoherence for
an individual particle.


title:
Volumes and geodesic ball packings to the regular prism tilings in
  $\widetilde{\mathbf{S}\mathbf{L}_2\mathbf{R}}$ space

abstract:
  After having investigated the regular prisms and prism tilings in the $\SLR$
space in the previous work \cite{Sz13-1} of the second author, we consider the
problem of geodesic ball packings related to those tilings and their symmetry
groups $\mathbf{pq2_1}$. $\SLR$ is one of the eight Thurston geometries that
can be derived from the 3-dimensional Lie group of all $2\times 2$ real
matrices with determinant one.
  In this paper we consider geodesic spheres and balls in $\SLR$ (even in
$\mathbf{SL_{\mathrm{2}}R})$, if their radii $\rho\in [0, \frac{\pi}{2})$, and
determine their volumes. Moreover, we consider the prisms of the above space
and compute their volumes, define the notion of the geodesic ball packing and
its density. We develop a procedure to determine the densities of the densest
geodesic ball packings for the tilings, or in this paper more precisely, for
their generating groups $\mathbf{pq2_1}$ (for integer rotational parameters
$p,q$; $3\le p, \frac{2p}{p-2} <q$). We look for those parameters $p$ and $q$
above, where the packing density large enough as possible. Now our record is
$0.567362$ for $(p, q) = (8, 10)$. These computations seem to be important,
since we do not know optimal ball packing, namely in the hyperbolic space
$\HYP$. We know only the density upper bound 0.85326, realized by horoball
packing of $\HYP$ to its ideal regular simplex tiling. Surprisingly, for the
so-called translation ball packings under the same groups $\mathbf{pq2_1}$ in
\cite{MSzV13} we have got larger density $0.841700$ for $(p, q) = (5, 10000
\rightarrow \infty)$ close to the above upper bound.
  We use for the computation and visualization of the $\SLR$ space its
projective model introduced by the first author in \cite{M97}.


title:
Characterization of a Be(p,xn) neutron source for fission yields
  measurements

abstract:
  We report on measurements performed at The Svedberg Laboratory (TSL) to
characterize a proton-neutron converter for independent fission yield studies
at the IGISOL-JYFLTRAP facility (Jyv\"askyl\"a, Finland). A 30 MeV proton beam
impinged on a 5 mm water-cooled Beryllium target. Two independent experimental
techniques have been used to measure the neutron spectrum: a Time of Flight
(TOF) system used to estimate the high-energy contribution, and a Bonner Sphere
Spectrometer able to provide precise results from thermal energies up to 20
MeV. An overlap between the energy regions covered by the two systems will
permit a cross-check of the results from the different techniques. In this
paper, the measurement and analysis techniques will be presented together with
some preliminary results.


title:
Counter effects of meridional flows and magnetic fields in stationary
  axisymmetric self-gravitating barotropes under the ideal MHD approximation:
  clear examples - toroidal configurations

abstract:
  We obtain the general forms for the current density and the vorticity from
the integrability conditions of the basic equations which govern the stationary
states of axisymmetric magnetized self-gravitating barotropic objects with
meridional flows under the ideal magnetohydrodynamics (MHD) approximation. As
seen from the stationary condition equations for such bodies, the presence of
the meridional flows and that of the poloidal magnetic fields act oppositely on
the internal structures.
  The different actions of these two physical quantities, the meridional flows
and the poloidal magnetic fields, could be clearly seen through stationary
structures of the toroidal gaseous configurations around central point masses
in the framework of Newtonian gravity because the effects of the two physical
quantities can be seen in an amplified way for toroidal systems compared to
those for spheroidal stars. The meridional flows make the structures more
compact, i.e. the widths of toroids thinner, while the poloidal magnetic fields
are apt to elongate the density contours in a certain direction depending on
the situation. Therefore, the simultaneous presence of the internal flows and
the magnetic fields would work as if there were no such different actions
within and around the stationary gaseous objects such as axisymmetric
magnetized toroids with internal motions around central compact objects under
the ideal MHD approximation, although these two quantities might exist in real
systems.


title:
Coexistence of oppositely flowing multi-$\varphi$-currents: Key to large
  toroidal magnetic fields within stars

abstract:
  We will show the importance of coexistence of oppositely flowing
$\varphi$-currents for magnetized stars to sustain strong toroidal magnetic
fields within the stars by an- alyzing stationary states of magnetized stars
with surface currents which flow in the opposite direction with respect to the
bulk currents within the stars. We have imposed boundary conditions for
currents and toroidal magnetic fields to vanish outside the stars. It is
important to note that these boundary conditions set an upper limit for the
total current within the stars. This upper limit for the total current results
in the presence of an upper limit for the magnitude of the energy for the
toroidal magnetic fields of the stars. If the stars could have the toroidal
surface currents which flow in the opposite directions to the internal toroidal
currents, the positively flowing inter- nal toroidal currents can become
stronger than the upper limit value of the current for configurations without
surface toroidal currents. Thus the energies for the toroidal magnetic fields
can become much larger than those for the magnetized stars with- out surface
toroidal currents. We have also analyzed the same phenomena appearing in
spherical incompressible stars for dipole-like magnetic fields with or without
sur- face toroidal currents by employing the zero-flux-boundary method. We have
applied those configurations with surface toroidal currents to magnetars and
discussed their flares through which magnetic helicities could arise outside
the stellar surfaces.


title:
Compact stars in Eddington-inspired Born-Infeld gravity: Anomalies
  associated with phase transitions

abstract:
  We study how generic phase transitions taking place in compact stars
constructed in the framework of the Eddington-inspired Born-Infeld (EiBI)
gravity can lead to anomalous behavior of these stars. For the case with
first-order phase transitions, compact stars in EiBI gravity with a positive
coupling parameter $\kappa $ exhibit a finite region with constant pressure,
which is absent in general relativity. However, for the case with a negative
$\kappa $, an equilibrium stellar configuration cannot be constructed. Hence,
EiBI gravity seems to impose stricter constraints on the microphysics of
stellar matter. Besides, in the presence of spatial discontinuities in the
sound speed $c_s$ due to phase transitions, the Ricci scalar is spatially
discontinuous and contains $\delta$-function singularities proportional to the
jump in $c_s^2$ acquired in the associated phase transition.


title: Uniform approximation of paraxial flat-topped beams

abstract:
  A uniform asymptotic theory of the free-space paraxial propagation of
coherent flattened Gaussian beams is proposed in the limit of nonsmall Fresnel
numbers. The pivotal role played by the error function in the mathematical
description of the related wavefield is stressed.


title:
Performance of the Metropolis algorithm on a disordered tree: The
  Einstein relation

abstract:
  Consider a $d$-ary rooted tree ($d\geq3$) where each edge $e$ is assigned an
i.i.d. (bounded) random variable $X(e)$ of negative mean. Assign to each vertex
$v$ the sum $S(v)$ of $X(e)$ over all edges connecting $v$ to the root, and
assume that the maximum $S_n^*$ of $S(v)$ over all vertices $v$ at distance $n$
from the root tends to infinity (necessarily, linearly) as $n$ tends to
infinity. We analyze the Metropolis algorithm on the tree and show that under
these assumptions there always exists a temperature $1/\beta$ of the algorithm
so that it achieves a linear (positive) growth rate in linear time. This
confirms a conjecture of Aldous [Algorithmica 22 (1998) 388-412]. The proof is
obtained by establishing an Einstein relation for the Metropolis algorithm on
the tree.


title:
Massive MIMO and Small Cells: Improving Energy Efficiency by Optimal
  Soft-Cell Coordination

abstract:
  To improve the cellular energy efficiency, without sacrificing
quality-of-service (QoS) at the users, the network topology must be densified
to enable higher spatial reuse. We analyze a combination of two densification
approaches, namely "massive" multiple-input multiple-output (MIMO) base
stations and small-cell access points. If the latter are operator-deployed, a
spatial soft-cell approach can be taken where the multiple transmitters serve
the users by joint non-coherent multiflow beamforming. We minimize the total
power consumption (both dynamic emitted power and static hardware power) while
satisfying QoS constraints. This problem is proved to have a hidden convexity
that enables efficient solution algorithms. Interestingly, the optimal solution
promotes exclusive assignment of users to transmitters. Furthermore, we provide
promising simulation results showing how the total power consumption can be
greatly improved by combining massive MIMO and small cells; this is possible
with both optimal and low-complexity beamforming.


title: Exotic phases of interacting p-band bosons

abstract:
  We study a model of interacting bosons that occupy the first excited p-band
states of a two-dimensional optical lattice. In contrast to the much studied
single band Bose-Hubbard Hamiltonian, this more complex model allows for
non-trivial superfluid phases associated with condensation at non-zero momentum
and staggered order of the orbital angular momentum in addition to the
superfluid-Mott insulator transition. More specifically, we observe staggered
orbital angular momentum order in the Mott phase at commensurate filling and
superfluidity at all densities. We also observe a transition between the
staggered angular momentum superfluid phase and a striped superfluid, with an
alternation of the phase of the superfluid along one direction. The transition
between these two phases was observed in a recent experiment, which is then
qualitatively well described by our model.


title: Distributed quantum election scheme

abstract:
  In an electronic voting protocol, a distributed scheme can be used for
forbidding the malicious acts of the voting administrator and the counter
during the election, but it cannot prevent them from collaborating to trace the
ballots and destroy their privacy after the election. We present a distributed
anonymous quantum key distribution scheme and further construct a distributed
quantum election scheme with a voting administrator made up of more than one
part. This quantum election scheme can resist the malicious acts of the voting
administrator and the counter after the election and can work in a system with
lossy and noisy quantum channels.


title: PT-Symmetric Nonlinear Metamaterials and Zero-Dimensional Systems

abstract:
  A one dimensional, parity-time (${\cal PT}$)-symmetric magnetic metamaterial
comprising split-ring resonators having both gain and loss is investigated. In
the linear regime, the transition from the exact to the broken ${\cal
PT}$-phase is determined through the calculation of the eigenfrequency spectrum
for two different configurations; the one with equidistant split-rings and the
other with the split-rings forming a binary pattern (${\cal PT}$ dimer chain).
The latter system features a two-band, gapped spectrum with its shape
determined by the gain/loss coefficient as well as the inter-element coupling.
In the presense of nonlinearity, the ${\cal PT}$ dimer chain with balanced gain
and loss supports nonlinear localized modes in the form of novel discrete
breathers below the lower branch of the linear spectrum. These breathers, that
can be excited from a weak applied magnetic field by frequency chirping, can be
subsequently driven solely by the gain for very long times. The effect of a
small imbalance between gain and loss is also considered. Fundamendal
gain-driven breathers occupy both sites of a dimer, while their energy is
almost equally partitioned between the two split-rings, the one with gain and
the other with loss. We also introduce a model equation for the investigation
of classical ${\cal PT}$ symmetry in zero dimensions, realized by a simple
harmonic oscillator with matched time-dependent gain and loss that exhibits a
transition from oscillatory to diverging motion. This behaviour is similar to a
transition from the exact to the broken ${\cal PT}$ phase in higher-dimensional
${\cal PT}-$ symmetric systems. A stability condition relating the parameters
of the problem is obtained in the case of piecewise constant gain/loss function
that allows for the construction of a phase diagram with alternating stable and
unstable regions.


title: Delooping of relative exact categories

abstract:
  We introduce a delooping model of relative exact categories. It gives us a
condition that the negative K-group of a relative exact category becomes
trivial.


title: Lambda Calculus Synopsis

abstract:
  This text gives a rough, but linear summary covering some key definitions,
notations, and propositions from Lambda Calculus: Its Syntax and Semantics, the
classical monograph by Barendregt. First, we define a theory of untyped
extensional lambda calculus. Then, some syntactic sugar, a system of
combinatory logic, and the fixed point theorem are described. The final section
introduces a topology on the set of lambda terms which is meant to explain an
illusory contradiction. Namely, functions defined on the set of lambda terms
are in the set of lambda terms itself, the latter being a countable set.
However, the functions on the set of lambda terms appear to be continuous with
respect to a topology of trees.


title: Perfect Lattices over Imaginary Quadratic Number Fields

abstract:
  We present an adaptation of Voronoi theory for imaginary quadratic number
fields of class number greater than 1. This includes a characterisation of
extreme Hermitian forms which is analogous to the classic characterisation of
extreme quadratic forms as well as a version of Voronoi's famous algorithm
which may be used to enumerate all perfect Hermitian forms for a given
imaginary quadratic number field in dimensions 2 and 3. We also present an
application of the algorithm which allows to determine generators of the
general linear group of an $\O_K$-lattice.


title:
How large is the contribution of cosmic web to $\Omega_\Lambda$ ? A
  preliminary study on a novel inhomogenous model

abstract:
  The distribution of matter in the universe shows a complex pattern, formed by
cluster of galaxies, voids and filaments denoted as cosmic web. Different
approaches have been proposed to model such structure in the framework of the
general relativity. Recently, one of us has proposed a generalization
($\Lambda$FB model) of the Fractal Bubble model, proposed by Wiltshire, which
accounts for such large scale structure. The $\Lambda$FB model is an evolution
of FB model and includes in a consistent way a description of inhomogeneous
matter distribution and a $\Lambda$ term. Here we analyze the $\Lambda$FB model
focusing on the relation between cosmological parameters. The main result is
the consistency of $\Lambda$CDM model values for $\Omega_{\Lambda0}$ ($\approx
0.7$) and $\Omega_{k0}$ ($|\Omega_{k0}|<\approx 0.01$) with a large fraction of
voids. This allows to quantify to which extent the inhomogeneous structure
could account for $\Lambda$ constant consistently with standard values of the
other cosmological parameters.


title: Neutron rich Carbon and Oxygen isotopes with an odd number of neutrons

abstract:
  We describe odd isotopes as formed of a core plus one neutron. We have
calculated the modification of single neutron energies brought by couplings of
the neutron with collective $2^+$ phonons in the cores. The results reproduce
very well the inversion of $2s$ and $1d_{5/2}$ shells in carbon isotopes up to
$^{19}$C while in oxygen isotopes the correction is also large but do not show
any inversion in agreement with experiments. The calculated energies are close
to the experimental ones in both series of isotopes except in $^{21}$C for the
$2s$ state for which our coupling is too weak.


title:
Speed and fluctuations of N-particle branching Brownian motion with
  spatial selection

abstract:
  We consider branching Brownian motion on the real line with the following
selection mechanism: Every time the number of particles exceeds a (large) given
number $N$, only the $N$ right-most particles are kept and the others killed.
After rescaling time by $\log^3N$, we show that the properly recentred position
of the $\lceil \alpha N\rceil$-th particle from the right, $\alpha\in(0,1)$,
converges in law to an explicitly given spectrally positive L\'evy process.
This behaviour has been predicted to hold for a large class of models falling
into the universality class of the FKPP equation with weak multiplicative noise
[Brunet et al., Phys. Rev. E \textbf{73}(5), 056126 (2006)] and is proven here
for the first time for such a model.


title: Optimal rank matrix algebras preconditioners

abstract:
  When a linear system Ax = y is solved by means of iterative methods (mainly
CG and GMRES) and the convergence rate is slow, one may consider a
preconditioner P. The use of such preconditioner changes the spectrum of the
matrix defining the system and could result into a great acceleration of the
convergence rate. The construction of optimal rank preconditioners is strongly
related to the possibility of splitting A as A = P + R + E, where E is a small
perturbation and R is of low rank. In the present work we extend the black-dot
algorithm for the computation of such splitting for P circulant, to the case
where P is in L, for several known low-complexity matrix algebras L. The
algorithm so obtained is particularly efficient when A is Toeplitz plus Hankel
like. We finally discuss in detail the existence and the properties of the
decomposition A = P + R + E when A is Toeplitz, also extending to the
phi-circulant and Hartley-type cases some results previously known for P
circulant.


title: On the definition of a confounder

abstract:
  The causal inference literature has provided a clear formal definition of
confounding expressed in terms of counterfactual independence. The literature
has not, however, come to any consensus on a formal definition of a confounder,
as it has given priority to the concept of confounding over that of a
confounder. We consider a number of candidate definitions arising from various
more informal statements made in the literature. We consider the properties
satisfied by each candidate definition, principally focusing on (i) whether
under the candidate definition control for all "confounders" suffices to
control for "confounding" and (ii) whether each confounder in some context
helps eliminate or reduce confounding bias. Several of the candidate
definitions do not have these two properties. Only one candidate definition of
those considered satisfies both properties. We propose that a "confounder" be
defined as a pre-exposure covariate C for which there exists a set of other
covariates X such that effect of the exposure on the outcome is unconfounded
conditional on (X,C) but such that for no proper subset of (X,C) is the effect
of the exposure on the outcome unconfounded given the subset. We also provide a
conditional analogue of the above definition; and we propose a variable that
helps reduce bias but not eliminate bias be referred to as a "surrogate
confounder." These definitions are closely related to those given by Robins and
Morgenstern [Comput. Math. Appl. 14 (1987) 869-916]. The implications that hold
among the various candidate definitions are discussed.


title:
SABOCA 350-micron and LABOCA 870-micron dust continuum imaging of IRAS
  05399-0121: mapping the dust properties of a pre- and protostellar core
  system

abstract:
  We present a 350 micron APEX/SABOCA map of IRAS 05399-0121/SMM 1, which is a
dense double-core system in Orion B9. We combined these data with our previous
LABOCA 870-micron data. The spatial resolution of the new SABOCA image, ~3400
AU, is about 2.6 times better than provided by LABOCA. We also make use of
Spitzer infrared observations to characterise the star-formation activity in
the source. The source is filamentary and remains a double-core system on the
3400 AU scale probed here, where the projected separation between IRAS 05399
and SMM 1 is 0.14 pc. The broadband spectral energy distribution of IRAS 05399
suggests that it is near the Stage 0/I borderline. A visual inspection of the
Spitzer/IRAC images provides hints of a quadrupolar-like jet morphology around
IRAS 05399, supporting the possibility that it is a binary system. The
temperature map reveals warm spots towards IRAS 05399 and the southeastern tip
of the source. These features are likely to be imprints of protostellar or
shock heating, while external heating could be provided by the nearby high-mass
star-forming region NGC 2024. A simple analysis suggests that the density
profile at the position of SMM 1 has the form ~r^-(2.3_{-0.9}^{+2.2}). The
source splitting into two subcores along the long axis can be explained by
cylindrical Jeans-type fragmentation but the steepness of the density profile
is shallower than what is expected for an isothermal cylinder. The difference
between the evolutionary stages of IRAS 05399 (protostellar) and SMM 1
(starless) suggests that the former has experienced a phase of rapid mass
accretion, supported by the very long outflow it drives. The protostellar jet
from IRAS 05399 might have influenced the nearby core SMM 1.


title: Geometric analysis on Cantor sets and trees

abstract:
  Using uniformization, Cantor type sets can be regarded as boundaries of
rooted trees. In this setting, we show that the trace of a first-order Sobolev
space on the boundary of a regular rooted tree is exactly a Besov space with an
explicit smoothness exponent. Further, we study quasisymmetries between the
boundaries of two trees, and show that they have rough quasiisometric
extensions to the trees. Conversely, we show that every rough quasiisometry
between two trees extends as a quasisymmetry between their boundaries. In both
directions we give sharp estimates for the involved constants. We use this to
obtain quasisymmetric invariance of certain Besov spaces of functions on Cantor
type sets.


title: On the Formulation of Performant SPARQL Queries

abstract:
  The combination of the flexibility of RDF and the expressiveness of SPARQL
provides a powerful mechanism to model, integrate and query data. However,
these properties also mean that it is nontrivial to write performant SPARQL
queries. Indeed, it is quite easy to create queries that tax even the most
optimised triple stores. Currently, application developers have little concrete
guidance on how to write "good" queries. The goal of this paper is to begin to
bridge this gap. It describes 5 heuristics that can be applied to create
optimised queries. The heuristics are informed by formal results in the
literature on the semantics and complexity of evaluating SPARQL queries, which
ensures that queries following these rules can be optimised effectively by an
underlying RDF store. Moreover, we empirically verify the efficacy of the
heuristics using a set of openly available datasets and corresponding SPARQL
queries developed by a large pharmacology data integration project. The
experimental results show improvements in performance across 6 state-of-the-art
RDF stores.


title: Smooth U(1) Gauge Fields in de Sitter Spacetime

abstract:
  Using the methods of Lie groups and Lie algebras, we solved U(1) gauge
potentials in the de Sitter background. Resulted gauge potentials are smooth on
the whole spacetime, satisfying the Lorentz gauge condition. It is shown that
electromagnetic fields in the de Sitter background could not be source free.


title: Granular convection and the Brazil nut effect in reduced gravity

abstract:
  We present laboratory experiments of a vertically vibrated granular medium
consisting of 1 mm diameter glass beads with embedded 8 mm diameter intruder
glass beads. The experiments were performed in the laboratory as well as in a
parabolic flight under reduced-gravity conditions (on Martian and Lunar gravity
levels). We measured the mean rise velocity of the large glass beads and
present its dependence on the fill height of the sample containers, the
excitation acceleration, and the ambient gravity level. We find that the rise
velocity scales in the same manner for all three gravity regimes and roughly
linearly with gravity.


title: Ab initio study of the TiO$_2$ Rutile(110)/Fe interface

abstract:
  Adsorption of Fe on the rutile (110)-surface is investigated by means of {\it
ab initio} density functional theory calculations. We discuss the deposition of
single Fe atoms, an increasing Fe coverage, as well as the adsorption of small
Fe clusters. It is shown that the different interface structures found in
experiment can be understood in terms of the adsorption of the Fe atoms landing
first on the rutile surface. On the one hand, strong interface bonds form if
single Fe atoms are deposited. On the other hand, the Fe-Fe bonds in deposited
Fe clusters lead to a three-dimensional growth mode. Mainly ionic Fe-oxide
bonds are formed in both cases and the electronic band gap of the surface is
reduced due to interface states. Besides the structural and electronic
properties, we discuss the influence of the interface on the magnetic
properties finding stable Fe moments and induced moments within the interface
which leads to a large spin polarization of the Fe atoms at the rutile (110)/Fe
interface.


title: Badly approximable points on manifolds

abstract:
  This paper is motivated by two problems in the theory of Diophantine
approximation, namely, Davenport's problem regarding badly approximable points
on submanifolds of a Euclidean space and Schmidt's problem regarding the
intersections of the sets of weighted badly approximable points. The problems
have been recently settled in dimension two but remain open in higher
dimensions. In this paper we develop new techniques that allow us to tackle
them in full generality. The techniques rest on lattice points counting and a
powerful quantitative result of Bernik, Kleinbock and Margulis. The main
theorem of this paper implies that any finite intersection of the sets of
weighted badly approximable points on any analytic nondegenerate submanifold of
$R^n$ has full dimension. One of the consequences of this result is the
existence of transcendental real numbers badly approximable by algebraic
numbers of any degree.


title:
Persistent enhancement of the carrier density in electron irradiated
  InAs nanowires

abstract:
  We report a significant and persistent enhancement of the conductivity in
free-standing non intentionnaly doped InAs nanowires upon irradiation in ultra
high vacuum. Combining four-point probe transport measurements performed on
nanowires with different surface chemistries, field-effect based measurements
and numerical simulations of the electron density, the change of the
conductivity is found to be caused by the increase of the surface free carrier
concentration. Although an electron beam of a few keV, typically used for the
inspection and the processing of materials, propagates through the entire
nanowire cross-section, we demonstrate that the nanowire electrical properties
are predominantly affected by radiation-induced defects occuring at the
nanowire surface and not in the bulk.


title:
Coupled Magnetic Resonator Optical Waveguides - mimicking spin waves in
  coupled metamaterials

abstract:
  Optical resonators are important devices that control the properties of light
and manipulate light-matter interaction. Various optical resonators are
designed and fabricated using different techniques. For example, in coupled
resonator optical waveguides, light energy is transported to other resonators
through near-field coupling. In recent years, magnetic optical resonators based
on LC resonance have been realized in several metallic microstructures. Such
devices possess stronger local resonance and lower radiation loss compared with
electric optical resonators. This study provides an overall introduction on the
latest progress in coupled magnetic resonator optical waveguide (CMROW).
Various waveguides composed of different magnetic resonators are presented and
Lagrangian formalism is used to describe the CMROW. Moreover, several
interesting properties of CMROW, such as abnormal dispersions and slow light
effects, are discussed and CMROW applications in nonlinear and quantum optics
are shown. Future novel nanophotonic devices can be developed using CMROW.


title: Inorganic photonic materials for lasers and biomedicine in the infrared

abstract:
  Inorganic photonic materials demonstrating luminescence in the infrared
spectral range (> 1 um) play a vital important role in modern information,
telecommunication, and biomedicine disciplines.


title: Directed self-assembly of spherical caps via confinement

abstract:
  In this work we use Monte Carlo simulations to study the phase behavior of
spherical caps confined between two parallel hard walls separated by a distance
H. The particle model consists of a hard sphere of diameter \sigma cut off by a
plane at a height \chi, and it is loosely based on mushroom cap-shaped
particles whose phase behavior was recently studied experimentally [E. K. Riley
and C. M. Liddell, Langmuir, 26, 11648 (2010)]. The geometry of the particles
is characterized by the reduced height \chi^* = \chi/\sigma, such that the
model extrapolates between hard spheres for \chi^* \leftarrow 1 and infinitely
thin hard platelets for \chi^* \letfarrow 0. Three different particle shapes
are investigated: (a) three-quarter height spherical caps (\chi^* = 3/4), (b)
one-half height spherical caps or hemispheres (\chi^* = 1/2), and (c)
one-quarter height spherical caps (\chi^* = 1/4). These three models are used
to rationalize the effect of particle shape, obtained by cutting off spheres at
different heights, on the entropy-driven self-assembly of the particles under
strong confinements; i.e., for 1 < H/\chi < 2.5. As H is varied, a sequence of
crystal structures are observed, including some having similar symmetry as that
of the structures observed in confined hard spheres on account of the remaining
spherical surface in the particles, but with additional features on account of
the particle shapes having intrinsic anisotropy and orientational degrees of
freedom. The \chi^* = 3/4 system is found to exhibit a phase diagram that is
most similar to the one obtained experimentally for the confined mushroom
cap-shaped colloidal particles under. A qualitative global phase diagram is
constructed that helps reveal the interrelations among different phases for all
the particle shapes and confinements studied.


title: Gauge Theory for Baryon and Lepton Numbers with Leptoquarks

abstract:
  Models where the baryon (B) and lepton (L) numbers are local gauge symmetries
that are spontaneously broken at a low scale are revisited. We find new
extensions of the Standard Model which predict the existence of fermions that
carry both baryon and lepton numbers (i.e., leptoquarks). The local baryonic
and leptonic symmetries can be broken at a scale close to the electroweak scale
and we do not need to postulate the existence of a large desert to satisfy the
experimental constraints on baryon number violating processes like proton
decay.


title: Dimensionless constants and cosmological measurements

abstract:
  The laws of physics have a set of fundamental constants, and it is generally
admitted that only dimensionless combinations of constants have physical
significance. These combinations include the electromagnetic and gravitational
fine structure constants, $\alpha=e^2/4\pi\epsilon_0\hbar c$ and
$\alpha_G=Gm_p^2/\hbar c$, along with the ratios of elementary-particles
masses. Cosmological measurements clearly depend on the values of these
constants in the past and can therefore give information on their time
dependence if the effects of time-varying constants can be separated from the
effects of cosmological parameters. The latter can be eliminated by using pairs
of redundant measurements and here we show how such pairs conspire to give
information only on dimensionless combinations of constants. Among other
possibilities, we will use distance measurements based on Baryon Acoustic
Oscillations (BAO) and on type Ia supernova. The fact that measurements yield
information only on dimensionless combinations is traced to the fact that
distances between co-moving points expand following the same function of time
that governs the redshift of photon wavelengths.


title: Simulation Chain for Acoustic Ultra-high Energy Neutrino Detectors

abstract:
  Acoustic neutrino detection is a promising approach for large-scale
ultra-high energy neutrino detectors in water. In this article, a Monte Carlo
simulation chain for acoustic neutrino detection devices in water is presented.
It is designed within the SeaTray/IceTray software framework. Its modular
architecture is highly flexible and makes it easy to adapt to different
environmental conditions, detector geometries, and hardware. The simulation
chain covers the generation of the acoustic pulse produced by a neutrino
interaction and the propagation to the sensors within the detector. In this
phase of the development, ambient and transient noise models for the
Mediterranean Sea and simulations of the data acquisition hardware, similar to
the one used in ANTARES/AMADEUS, are implemented. A pre-selection scheme for
neutrino-like signals based on matched filtering is employed, as it can be used
for on-line filtering. To simulate the whole processing chain for experimental
data, signal classification and acoustic source reconstruction algorithms are
integrated. In this contribution, an overview of the design and capabilities of
the simulation chain will be given, and some applications and preliminary
studies will be presented.


title: Heat content and inradius for regions with a Brownian boundary

abstract:
  In this paper we consider $\beta[0; s]$, Brownian motion of time length $s >
0$, in $m$-dimensional Euclidean space $\mathbb R^m$ and on the $m$-dimensional
torus $\mathbb T^m$. We compute the expectation of (i) the heat content at time
$t$ of $\mathbb R^m\setminus \beta[0; s]$ for fixed $s$ and $m = 2,3$ in the
limit $t \downarrow 0$, when $\beta[0; s]$ is kept at temperature 1 for all $t
> 0$ and $\mathbb R^m\setminus \beta[0; s]$ has initial temperature 0, and (ii)
the inradius of $\mathbb R^m\setminus \beta[0; s]$ for $m = 2,3,\cdots$ in the
limit $s \rightarrow \infty$.


title:
A general theory for nonlinear sufficient dimension reduction:
  Formulation and estimation

abstract:
  In this paper we introduce a general theory for nonlinear sufficient
dimension reduction, and explore its ramifications and scope. This theory
subsumes recent work employing reproducing kernel Hilbert spaces, and reveals
many parallels between linear and nonlinear sufficient dimension reduction.
Using these parallels we analyze the properties of existing methods and develop
new ones. We begin by characterizing dimension reduction at the general level
of $\sigma$-fields and proceed to that of classes of functions, leading to the
notions of sufficient, complete and central dimension reduction classes. We
show that, when it exists, the complete and sufficient class coincides with the
central class, and can be unbiasedly and exhaustively estimated by a
generalized sliced inverse regression estimator (GSIR). When completeness does
not hold, this estimator captures only part of the central class. However, in
these cases we show that a generalized sliced average variance estimator
(GSAVE) can capture a larger portion of the class. Both estimators require no
numerical optimization because they can be computed by spectral decomposition
of linear operators. Finally, we compare our estimators with existing methods
by simulation and on actual data sets.


title: Hybrid Bloch-Anderson localization of light

abstract:
  We investigate the interplay of Bloch oscillations and Anderson localization
in optics. Gradual washing out of Bloch oscillations and the formation of
nearly stationary averaged intensity distributions, which are symmetric for
narrow and strongly asymmetric for broad input excitations, are observed
experimentally in laser-written waveguide arrays. At large disorder levels
Bloch oscillations are completely destroyed and both narrow and wide
excitations lead to symmetric stationary averaged intensity distributions with
exponentially decaying tails.


title: Awaking the vacuum with spheroidal shells

abstract:
  It has been shown that well-behaved spacetimes may induce the vacuum
fluctuations of some nonminimally coupled free scalar fields to go through a
phase of exponential growth. Here, we discuss this mechanism in the context of
spheroidal thin shells emphasizing the consequences of deviations from
spherical symmetry.


title: Commuting and noncommuting infinitesimals

abstract:
  Infinitesimals are natural products of the human imagination. Their history
goes back to the Greek antiquity. Their role in the calculus and analysis has
seen dramatic ups and downs. They have stimulated strong opinions and even
vitriol. Edwin Hewitt developed hyperreal fields in the 1940s. Abraham
Robinson's infinitesimals date from the 1960s. A noncommutative version of
infinitesimals, due to Alain Connes, has been in use since the 1990s. We review
some of the hyperreal concepts, and compare them with some of the concepts
underlying noncommutative geometry.

categories: math.HO math-ph math.CA math.LO math.MP math.OA


title:
On the development of the Papaloizou-Pringle instability of the black
  hole-torus systems and quasi-periodic oscillations

abstract:
  We present the numerical study of dynamical instability of a
pressure-supported relativistic torus, rotating around the black hole with a
constant specific angular momentum on a fixed space-time background, in case of
perturbation by a matter coming from the outer boundary. Two dimensional
hydrodynamical equations are solved at equatorial plane using the HRSCS to
study the effect of perturbation on the stable systems. We have found that the
perturbed torus creates an instability which causes the gas falling into the
black hole in a certain dynamical time. All the models indicate an oscillating
torus with certain frequency around their instant equilibrium. The dynamic of
the accreted torus varies with the size of initial stable torus, black hole
spin and other variables, such as Mach number, sound speed, cusp location of
the torus, etc. The mass accretion rate is slightly proportional to the
torus-to-hole mass ratio in the black hole-torus system, but it strongly
depends on the cusp location of the torus. The cusp located in the
equipotential surfaces of the effective potential moves outwards into the
torus. The dynamical change of the torus increases the mass accretion rate and
triggers the Papaloizou-Pringle instability. It is also observed that the
growth of the $m=1$ mode of the Papaloizou-Pringle instability occurs for a
wide range of fluid and hydrodynamical parameters and a black hole spin. We
have also computed the QPOs from the oscillating relativistic torus.


title: Structure Finding in Cosmological Simulations: The State of Affairs

abstract:
  The ever increasing size and complexity of data coming from simulations of
cosmic structure formation demands equally sophisticated tools for their
analysis. During the past decade, the art of object finding in these
simulations has hence developed into an important discipline itself. A
multitude of codes based upon a huge variety of methods and techniques have
been spawned yet the question remained as to whether or not they will provide
the same (physical) information about the structures of interest. Here we
summarize and extent previous work of the "halo finder comparison project": we
investigate in detail the (possible) origin of any deviations across finders.
To this extent we decipher and discuss differences in halo finding methods,
clearly separating them from the disparity in definitions of halo properties.
We observe that different codes not only find different numbers of objects
leading to a scatter of up to 20 per cent in the halo mass and Vmax function,
but also that the particulars of those objects that are identified by all
finders differ. The strength of the variation, however, depends on the property
studied, e.g. the scatter in position, bulk velocity, mass, and the peak value
of the rotation curve is practically below a few per cent, whereas derived
quantities such as spin and shape show larger deviations. Our study indicates
that the prime contribution to differences in halo properties across codes
stems from the distinct particle collection methods and -- to a minor extent --
the particular aspects of how the procedure for removing unbound particles is
implemented. We close with a discussion of the relevance and implications of
the scatter across different codes for other fields such as semi-analytical
galaxy formation models, gravitational lensing, and observables in general.


title:
The symmetry, period and Calabi-Yau dimension of finite dimensional mesh
  algebras

abstract:
  Within the class of finite dimensional mesh algebras, also called m-fold mesh
algebras, we identify those which are symmetric and those whose stable module
category is weakly Calabi-Yau. We also give, in combinatorial terms, explicit
formulas for the period of any such algebra, and for the Calabi-Yau Frobenius
and stable Calabi-Yau dimensions, when they are defined.