title: A Bandwidth-saving Optimization for MPI Broadcast Collective Operation

abstract:
  The efficiency and scalability of MPI collective operations, in particular
the broadcast operation, plays an integral part in high performance computing
applications. MPICH, as one of the contemporary widely-used MPI software
stacks, implements the broadcast operation based on point-to-point operation.
Depending on the parameters, such as message size and process count, the
library chooses to use different algorithms, as for instance binomial
dissemination, recursive-doubling exchange or ring all-to-all broadcast
(allgather). However, the existing broadcast design in latest release of MPICH
does not provide good performance for large messages (\textit{lmsg}) or medium
messages with non-power-of-two process counts (\textit{mmsg-npof2}) due to the
inner suboptimal ring allgather algorithm. In this paper, based on the native
broadcast design in MPICH, we propose a tuned broadcast approach with
bandwidth-saving in mind catering to the case of \textit{lmsg} and
\textit{mmsg-npof2}. Several comparisons of the native and tuned broadcast
designs are made for different data sizes and program sizes on Cray XC40
cluster. The results show that the performance of the tuned broadcast design
can get improved by a range from 2\% to 54\% for \textit{lmsg} and
\textit{mmsg-npof2} in terms of user-level testing.


title:
Resonant Plasmon-Axion Excitations Induced by Charge Density Wave Order
  in Weyl Semimetal

abstract:
  We investigate the charge excitations of a Weyl semimetal in the axionic
charge density wave (axionic CDW) state. While it has been shown that the
topological response (anomalous Hall conductivity) is protected against the CDW
state, we find that the long wavelength plasmon excitation is radically
influenced by the dynamics of the CDW order parameter. In the normal state, we
show that an undamped collective mode should exist at q~Q_(CDW) if there is an
attractive interaction favoring the formation of the CDW state. The undamped
nature of this collective mode is attributed to a gap-like feature in the
particle-hole continuum at q~Q_(CDW) due to the chirality of the Weyl nodes,
which is not seen in other materials with CDW instability. In the CDW state,
the long wavelength plasmon excitations become more dispersive due to the
additional interband scattering not allowed in the normal state. Moreover,
because the translational symmetry is spontaneously broken, Umklapp scattering,
the process conserving the total momentum only up to nQ_(CDW) with n an integer
and Q_(CDW) the ordering wave vector, emerges in the CDW state. We find that
the plasmon excitation couples to the phonon mode of the CDW order via the
Umklapp scattering, leading to two branches of resonant collective modes
observable in the density-density correlation function at q~0 and q~Q_(CDW).
Based on our analysis, we propose that measuring these resonant plasmon-axion
excitations around q~0 and q~Q_(CDW) by the momentum-resolved electron energy
loss spectroscopy (M-EELS) could serve as a reliable way to detect the axionic
CDW state in Weyl semimetals.


title: Ultraviolet divergences in non-renormalizable supersymmetric theories

abstract:
  We present a pedagogical review of our current understanding of the
ultraviolet structure of N = (1,1) 6D supersymmetric Yang-Mills theory and of N
= 8 4D supergravity. These theories are not renormalizable, they involve power
ultraviolet divergences and, in all probability, an infinite set of
higher-dimensional counterterms that contribute to on-mass-shell scattering
amplitudes.
  A specific feature of supersymmetric theories (especially, of extended
supersymmetric theories) is that these counterterms may not be invariant off
shell under the full set of supersymmetry transformations. The
lowest-dimensional nontrivial counterterm is supersymmetric on shell. Still
higher counterterms may lose even the on-shell invariance. On the other hand,
the full effective Lagrangian, generating the amplitudes and representing an
infinite sum of counterterms, still enjoys the complete symmetry of original
theory.
  We also discuss simple supersymmetric quantum-mechanical models that exhibit
the same behaviour.


title: Con-Patch: When a Patch Meets its Context

abstract:
  Measuring the similarity between patches in images is a fundamental building
block in various tasks. Naturally, the patch-size has a major impact on the
matching quality, and on the consequent application performance. Under the
assumption that our patch database is sufficiently sampled, using large patches
(e.g. 21-by-21) should be preferred over small ones (e.g. 7-by-7). However,
this "dense-sampling" assumption is rarely true; in most cases large patches
cannot find relevant nearby examples. This phenomenon is a consequence of the
curse of dimensionality, stating that the database-size should grow
exponentially with the patch-size to ensure proper matches. This explains the
favored choice of small patch-size in most applications.
  Is there a way to keep the simplicity and work with small patches while
getting some of the benefits that large patches provide? In this work we offer
such an approach. We propose to concatenate the regular content of a
conventional (small) patch with a compact representation of its (large)
surroundings - its context. Therefore, with a minor increase of the dimensions
(e.g. with additional 10 values to the patch representation), we
implicitly/softly describe the information of a large patch. The additional
descriptors are computed based on a self-similarity behavior of the patch
surrounding.
  We show that this approach achieves better matches, compared to the use of
conventional-size patches, without the need to increase the database-size.
Also, the effectiveness of the proposed method is tested on three distinct
problems: (i) External natural image denoising, (ii) Depth image
super-resolution, and (iii) Motion-compensated frame-rate up-conversion.


title:
An Approximation of Local Antiderivatives of Relative Differential on
  Arithmetic Surface

abstract:
  Let $\omega$ be a relative differential on aithmetic surface $X$. We
construct a family of rational functions $G_x$ on $X\otimes\Bbb{C}$, which can
approximate local antiderivatives of $\omega$ over an open set on
$X\otimes\Bbb{C}$. From this family of functions, we construct a rational
function $G_2$ on $X$. The function $G_2$ can generate an element in the ring
of integers of a number field, which can approximate an inner product produced
by $\omega$ and the conjugate of $\omega$ over an open set on
$X\otimes\Bbb{C}$. This will give a relation between the height of a rational
curve $E_P$ on $X$ and the canonical norm of $\omega$ on $X\otimes\Bbb{C}$.
This relation will give an upper bound for the height of $E_P$ under a few
assumptions.


title:
Galaxy bispectrum, primordial non-Gaussianity and redshift space
  distortions

abstract:
  Measurements of the non-Gaussianity of the primordial density field have the
power to considerably improve our understanding of the physics of inflation.
Indeed, if we can increase the precision of current measurements by an order of
magnitude, a null-detection would rule out many classes of scenarios for
generating primordial fluctuations. Large-scale galaxy redshift surveys
represent experiments that hold the promise to realise this goal. Thus, we
model the galaxy bispectrum and forecast the accuracy with which it will probe
the parameter $f_{\rm NL}$, which represents the degree of primordial
local-type non Gaussianity. Specifically, we address the problem of modelling
redshift space distortions (RSD) in the tree-level galaxy bispectrum including
$f_{\rm NL}$. We find novel contributions associated with RSD, with the
characteristic large scale amplification induced by local-type non-Gaussianity.
These RSD effects must be properly accounted for in order to obtain un-biased
measurements of $f_{\rm NL}$ from the galaxy bispectrum. We propose an analytic
template for the monopole which can be used to fit against data on large
scales, extending models used in the recent measurements. Finally, we perform
idealised forecasts on $\sigma_{f_{\rm NL}}$ -- the accuracy of the
determination of local non-linear parameter $f_{\rm NL}$ -- from measurements
of the galaxy bispectrum. Our findings suggest that current surveys can in
principle provide $f_{\rm NL}$ constraints competitive with Planck, and future
surveys could improve them further.


title:
Analysis of renewable energy sources and electric vehicle penetration
  into energy systems predominantly based on lignite

abstract:
  We consider an integration of renewable energy into transport and electricity
sectors through vehicle to grid (V2G) technologies for an energy system that is
predominantly based on lignite. The national energy system of Macedonia is
modeled using EnergyPLAN which integrates energy for electricity, transport and
heat, and includes hourly fluctuations in human needs and the environment. We
show that electric-vehicles can provide the necessary storage enabling a fully
renewable energy profile for Macedonia that can match the country's growing
demand for energy. Furthermore, a large penetration of electric vehicles leads
to a dramatic reduction of 47% of small particles and other air pollutants
generated by car traffic in 2050.


title:
UCTM2: An updated User friendly Configurable Trigger, scaler and delay
  Module for nuclear and particle physics

abstract:
  We developed a highly integrated and versatile electronic module to equip
small nuclear physics experiments and lab teaching classes: the User friendly
Configurable Trigger, scaler and delay Module for nuclear and particle physics
(UCTM). It is configurable through a Graphical User Interface (GUI) and
provides a large number of possible trigger conditions without any Hardware
Description Language (HDL) required knowledge. This new version significantly
enhances the previous capabilities by providing two additional features: signal
digitization and time measurements. The design, performances and a typical
application are presented.


title: Measurement of 1.7 to 74 MeV polarised gamma rays with the HARPO TPC

abstract:
  Current {\gamma}-ray telescopes based on photon conversions to
electron-positron pairs, such as Fermi, use tungsten converters. They suffer of
limited angular resolution at low energies, and their sensitivity drops below 1
GeV. The low multiple scattering in a gaseous detector gives access to higher
angular resolution in the MeV-GeV range, and to the linear polarisation of the
photons through the azimuthal angle of the electron-positron pair.
  HARPO is an R&D program to characterise the operation of a TPC (Time
Projection Chamber) as a high angular-resolution and sensitivity telescope and
polarimeter for {\gamma} rays from cosmic sources. It represents a first step
towards a future space instrument. A 30 cm cubic TPC demonstrator was built,
and filled with 2 bar argon-based gas. It was put in a polarised {\gamma}-ray
beam at the NewSUBARU accelerator in Japan in November 2014. Data were taken at
different photon energies from 1.7 MeV to 74 MeV, and with different
polarisation configurations. The electronics setup is described, with an
emphasis on the trigger system. The event reconstruction algorithm is quickly
described, and preliminary measurements of the polarisation of 11 MeVphotons
are shown.


title: Strong submultiplicativity of the Poincare metric

abstract:
  We give a direct proof of an important result of Solynin which says that the
Poincar\'e metric is a strongly submultiplicative domain function. This result
is then used to define a new capacity for compact subsets of the complex plane
$\mathbb{C}$, which might be called Poincar\'e capacity. If the compact set $K
\subseteq \mathbb{C}$ is connected, then the Poincar\'e capacity of $K$ is the
same as the logarithmic capacity of $K$. In this special case, the
submultiplicativity is well--known and can be stated as an inequality for the
normalized conformal map onto the complement of $K$. Using the connection
between Poincar\'e metrics and universal covering maps this inequality is
extended to the much wider class of universal covering maps.


title: Regularity of the free boundary in the biharmonic obstacle problem

abstract:
  In this article we use flatness improvement argument to study the regularity
of the free boundary for the biharmonic obstacle problem with zero obstacle.
Assuming that the solution is almost one-dimensional, and that the
non-coincidence set is an non-tangentially accessible (NTA) domain, we derive
the $C^{1,\alpha}$-regularity of the free boundary in a small ball centered at
the origin.
  From the $C^{1,\alpha}$-regularity of the free boundary we conclude that the
solution to the biharmonic obstacle problem is locally $ C^{3,\alpha}$ up to
the free boundary, and therefore $C^{2,1} $. In the end we study an example,
showing that in general $ C^{2,\frac{1}{2}}$ is the best regularity that a
solution may achieve in dimension $n \geq 2$.


title: Local smoothing for the quantum Liouville equation

abstract:
  We analyze in this work the regularity properties of the density operator
solu- tion to the quantum Liouville equation. As was recently done for the
Strichartz inequalities, we extend to systems of orthonormal functions the
local smoothing estimates satisfied by the solutions to the Schr\"odinger
equation. We show in par- ticular that the local density associated to the
solution to the free, linear, quantum Liouville equation admits locally
fractional derivatives of given order provided the data belong to some Schatten
spaces.


title: A Report on Shape Deformation with a Stretching and Bending Energy

abstract:
  In this report we describe a mesh editing system that we implemented that
uses a natural stretching and bending energy defined over smooth surfaces. As
such, this energy behaves uniformly under various mesh resolutions. All of the
elements of our approach already exist in the literature. We hope that our
discussions of these energies helps to shed light on the behaviors of these
methods and provides a unified discussion of these methods.


title:
The matroid secretary problem for minor-closed classes and random
  matroids

abstract:
  We prove that for every proper minor-closed class $M$ of matroids
representable over a prime field, there exists a constant-competitive matroid
secretary algorithm for the matroids in $M$. This result relies on the
extremely powerful matroid minor structure theory being developed by Geelen,
Gerards and Whittle.
  We also note that for asymptotically almost all matroids, the matroid
secretary algorithm that selects a random basis, ignoring weights, is
$(2+o(1))$-competitive. In fact, assuming the conjecture that almost all
matroids are paving, there is a $(1+o(1))$-competitive algorithm for almost all
matroids.


title:
Advective-diffusive motion on large scales from small-scale dynamics
  with an internal symmetry

abstract:
  We consider coupled diffusions in $n$-dimensional space and on a compact
manifold and the resulting effective advective-diffusive motion on large scales
in space. The effective drift (advection) and effective diffusion are
determined as a solvability conditions in a multi-scale analysis. As an example
we consider coupled diffusions in $3$-dimensional space and on the group
manifold $SO(3)$ of proper rotations, generalizing results obtained by H.
Brenner (1981). We show in detail how the analysis can be conveniently be
carried out using local charts and invariance arguments. As a further example
we consider coupled diffusions in $2$-dimensional complex space and on the
group manifold $SU(2)$. We show that although the local operators may be the
same as for $SO(3)$, due to the global nature of the solvability conditions the
resulting diffusion will be different, and generally more isotropic.


title: Event-by-event multiplicity fluctuations in Pb-Pb collisions in ALICE

abstract:
  Fluctuations of various observables in heavy-ion collisions at
ultra-relativistic energies have been extensively studied as they provide
important signals regarding the formation of a Quark-Gluon Plasma (QGP).
Because of the large number of produced particles in each event, a detailed
study of event-by-event multiplicity fluctuations has been proposed as one of
the signatures of the phase transition. In addition, the understanding of
multiplicity fluctuations is essential for other event-by-event measurements.
In the present work, we have calculated the scaled variance ($\omega_{\rm
ch}=\sigma^{\rm 2} / \mu$) of the charged-particle multiplicity distributions
as a function of centrality in Pb-Pb collisions at LHC energies. Here, $\mu$
and $\sigma$ denote the mean and the width of the multiplicity distributions,
respectively. The trend of scaled variances as a function of centrality is
presented and discussed. Volume fluctuations play an important role while
measuring the multiplicity fluctuations, which are also discussed. The results
are expected to provide vital input to theoretical model calculations.


title: First Order BSPDEs in higher dimension for optimal control problems

abstract:
  The paper studies the First Order BSPDEs (Backward Stochastic Partial
Differential Equations) suggested earlier for a case of multidimensional state
domain with a boundary. These equations represent analogs of
Hamilton-Jacobi-Bellman equations and allow to construct the value function for
stochastic optimal control problems with unspecified dynamics where the
underlying processes do not necessarily satisfy stochastic differential
equations of a known kind with a given structure. The problems considered arise
in financial modelling.


title: Nonlinear waves in $\cal PT$-symmetric systems

abstract:
  Recent progress on nonlinear properties of parity-time ($\cal PT$-) symmetric
systems is comprehensively reviewed in this article. $\cal PT$ symmetry started
out in non-Hermitian quantum mechanics, where complex potentials obeying $\cal
PT$ symmetry could exhibit all-real spectra. This concept later spread out to
optics, Bose-Einstein condensates, electronic circuits, and many other physical
fields, where a judicious balancing of gain and loss constitutes a $\cal
PT$-symmetric system. The natural inclusion of nonlinearity into these $\cal
PT$ systems then gave rise to a wide array of new phenomena which have no
counterparts in traditional dissipative systems. Examples include the existence
of continuous families of nonlinear modes and integrals of motion,
stabilization of nonlinear modes above $\cal PT$-symmetry phase transition,
symmetry breaking of nonlinear modes, distinctive soliton dynamics, and many
others. In this article, nonlinear $\cal PT$-symmetric systems arising from
various physical disciplines are presented; nonlinear properties of these
systems are thoroughly elucidated; and relevant experimental results are
described. In addition, emerging applications of $\cal PT$ symmetry are pointed
out.


title: A new expander and improved bounds for $A(A+A)$

abstract:
  The main result in this paper concerns a new five-variable expander. It is
proven that for any finite set of real numbers $A$,
$$|\{(a_1+a_2+a_3+a_4)^2+\log a_5 :a_1,a_2,a_3,a_4,a_5 \in A \}| \gg
\frac{|A|^2}{\log |A|}.$$ This bound is optimal, up to logarithmic factors. The
paper also gives new lower bounds for $|A(A-A)|$ and $|A(A+A)|$, improving on
results from arXiv:1312.6438. The new bounds are $$|A(A-A)| \gtrapprox
|A|^{3/2+\frac{1}{34}}$$ and $$|A(A+A)| \gtrapprox |A|^{3/2+\frac{5}{242}}.$$


title: Robust principal graphs for data approximation

abstract:
  Revealing hidden geometry and topology in noisy data sets is a challenging
task. Elastic principal graph is a computationally efficient and flexible data
approximator based on embedding a graph into the data space and minimizing the
energy functional penalizing the deviation of graph nodes both from data points
and from pluri-harmonic configuration (generalization of linearity). The
structure of principal graph is learned from data by application of a
topological grammar which in the simplest case leads to the construction of
principal curves or trees. In order to more efficiently cope with noise and
outliers, here we suggest using a trimmed data approximation term to increase
the robustness of the method. The modification of the method that we suggest
does not affect either computational efficiency or general convergence
properties of the original elastic graph method. The trimmed elastic energy
functional remains a Lyapunov function for the optimization algorithm. On
several examples of complex data distributions we demonstrate how the robust
principal graphs learn the global data structure and show the advantage of
using the trimmed data approximation term for the construction of principal
graphs and other popular data approximators.


title: Multi-velocity neural networks for gesture recognition in videos

abstract:
  We present a new action recognition deep neural network which adaptively
learns the best action velocities in addition to the classification. While deep
neural networks have reached maturity for image understanding tasks, we are
still exploring network topologies and features to handle the richer
environment of video clips. Here, we tackle the problem of multiple velocities
in action recognition, and provide state-of-the-art results for gesture
recognition, on known and new collected datasets. We further provide the
training steps for our semi-supervised network, suited to learn from huge
unlabeled datasets with only a fraction of labeled examples.


title: Fuzzy Commitment Scheme based on Reed Solomon Codes

abstract:
  The conventional commitment scheme requires both commitment string and a
valid key for the sender to verify his commitment. Differ from the conventional
commitment scheme; fuzzy commitment scheme accepts the key that is similar to
the original key. The new opening key, not identical to the original key,
differs from the initial key in some suitable metrics. The fuzziness in the
fuzzy commitment scheme tolerate small amount of corruptions. The fuzzy
commitment scheme based on the cryptographic hash functions suffers security
imperfections. Thus, this paper combines the fuzzy commitment scheme with the
Reed Solomon error correction codes, which are capable of correcting certain
number of errors. As a result, Reed Solomon code proves better alternative for
fuzzy commitment scheme than hash functions, as the Reed Solomon codes are more
secure than the hashing techniques. Moreover, the Fuzzy Commitment Scheme based
on Reed Solomon codes provides security at two levels that making it suitable
for securing data. This paper explore the efficiency of executing fuzzy
commitment scheme in conjunction with Reed Solomon code as a novel better
alternative to the conventional commitment scheme.


title:
New experiments demand for a more precise analysis of continuum spectrum
  in 6He: technical details and formalism

abstract:
  A simple three-body model of 6He is extended to include sd-continuum states
in the picture in addition to the already investigated p-states. The role of
different continuum components in the weakly bound nucleus 6He is studied by
coupling unbound spd-waves of 5He by using simple pairing contact-delta
interaction. The main focus of this paper is to outline the procedure that
allows the calculation of different configurations of 6He including continuum
states and to set up basic ingredients for computations. The method and results
discussed here will be used for the calculation of monopole, dipole, quadrupole
and octupole response of 6He.


title: The second Konus-Wind catalog of short gamma-ray bursts

abstract:
  In this catalog, we present the results of a systematic study of 295 short
gamma-ray bursts (GRBs) detected by Konus-Wind (KW) from 1994 to 2010. From the
temporal and spectral analyses of the sample, we provide the burst durations,
the spectral lags, the results of spectral fits with three model functions, the
total energy fluences and the peak energy fluxes of the bursts. We discuss
evidence found for an additional power-law spectral component and the presence
of extended emission in a fraction of the KW short GRBs. Finally, we consider
the results obtained in the context of the Type I (merger-origin) / Type II
(collapsar-origin) classifications.


title: On the Structure of the Bochner-Martinelli Residue Currents

abstract:
  We study residue currents of the Bochner--Martinelli type using their
relationship with Mellin transforms of residue integrals. We present the
structure formula for residue currents associated with monomial mappings: they
admit representations as sums of products of residue currents, principal value
currents and hypergeometric functions.


title:
Evolution of the distance scale factor and the Hubble parameter in the
  light of Plancks results

abstract:
  As the 2015 results of Plancks mission have recently been made available, it
is interesting to check the evolution of the scale factor and of the Hubble
parameter in the light of these results. Two models in line with Einsteins
field equations and with the hot big bang scenario for a flat Universe are used
to allow a comparison : (1) the classical one using density parameters for
matter content (baryonic and dark matter) and dark energy ; (2) an alternative
model, already used in the past, and assuming the Hubble parameter to contain a
term constant in time. Both models are coherent with each other except for some
discrepancy about the density, which can be ascribed to the different
hypotheses made. This opens a way for further interpretation of the origin of
dark energy.


title:
Oscillatory Double-Diffusive Convection in a Horizontal Cavity with
  Soret and Dufour Effects

abstract:
  Oscillatory double-diffusive convection in horizontal cavity with Soret and
Dufour effects is investigated numerically based on SIMPLE algorithm with QUICK
scheme in non-uniform staggered grid system. The results show that
double-diffusive convection develops from steady-state convection-dominated,
periodic oscillatory, quasi-periodic oscillatory to chaotic flow, and finally
return to periodic oscillation as buoyancy ratio increases. Moreover,
fundamental frequency and fluctuation amplitude increase with buoyancy ratio.
As Rayleigh number increases, transition trendy of oscillatory convection is
similar to that of buoyancy ratio. But the return of periodic oscillation from
chaos is not obtained as Rayleigh number increases. As aspect ratio decreases,
the oscillatory convection evolves from periodic into steady-state. In
addition, fundamental frequency increases at first and then decreases while
fluctuation amplitude decreases with aspect ratio.


title: GMRT detections of low mass young stars at 323 and 608 MHz

abstract:
  We present the results of a pathfinder project conducted with the Giant
Metrewave Radio Telescope (GMRT) to investigate protostellar systems at low
radio frequencies. The goal of these investigations is to locate the break in
the free-free spectrum where the optical depth equals unity in order to
constrain physical parameters of these systems, such as the mass of the ionised
gas surrounding these young stars. We detect all three target sources, L1551
IRS 5 (Class I), T Tau and DG Tau (Class II), at frequencies 323 and 608 MHz
(wavelengths 90 and 50 cm, respectively). These are the first detections of low
mass young stellar objects (YSOs) at such low frequencies. We combine these new
GMRT data with archival information to construct the spectral energy
distributions for each system and find a continuation of the optically thin
free-free spectra extrapolated from higher radio frequencies to 323 MHz for
each target. We use these results to place limits on the masses of the ionised
gas and average electron densities associated with these young systems on
scales of ~1000 au. Future observations with higher angular resolution at lower
frequencies are required to constrain these physical parameters further.


title:
Contributions to a conjecture of Mueller and Schmidt on Thue
  inequalities

abstract:
  Let $F(X,Y)=\sum\limits_{i=0}^sa_iX^{r_i}Y^{r-r_i}\in\mathbb{Z}[X,Y]$ be a
form of degree $r=r_s\geq 3$, irreducible over $\mathbb{Q}$ and having at most
$s+1$ non-zero coefficients. Mueller and Schmidt showed that the number of
solutions of the Thue inequality \[
  |F(X,Y)|\leq h \] is $\ll s^2h^{2/r}(1+\log h^{1/r})$. They
$\textit{conjectured}$ that $s^2$ may be replaced by $s$. Let \[
  \Psi = \max_{0\leq i\leq s} \max\left(
\sum_{w=0}^{i-1}\frac{1}{r_i-r_w},\sum_{w= i+1}^{s}\frac{1}{r_w-r_i}\right). \]
  Then we show that $s^2$ may be replaced by $\max(s\log^3s, se^{\Psi})$. We
also show that if $|a_0|=|a_s|$ and $|a_i|\leq |a_0|$ for $1\leq i\leq s-1$,
then $s^2$ may be replaced by $s\log^{3/2}s$. In particular, this is true if
$a_i\in\{-1,1\}$.


title:
A regularized penalty-multiplier method for approximating cavitation
  solutions with prescribed cavity volume size

abstract:
  Let $\Omega\in\mathbb{R}^n$ be the region occupied by a body and let
$\mathbf{x}_0$ be a flaw point in $\Omega$. Let $E(\cdot)$ be an energy
functional (defined on some appropriate admissible set of deformations of
$\Omega$). For $V>0$ fixed, we let $\mathbf{u}_V$ be a minimizer of $E(\cdot)$
among the set of deformations constrained to form a hole of volume $V$ at
$\mathbf{x}_0$. In this paper we describe a regularized penalty--multiplier
method and its convergence properties for the computation of both
$\mathbf{u}_V$ and $E(\mathbf{u}_V)$. In particular, we show that as the
regularization parameter goes to zero, the regularized constrained minimizers
converge weakly in
$W^{1,p}(\Omega\setminus\overline{\mathcal{B}_{\delta}(\mathbf{x}_0)})$ to
$\mathbf{u}_{V}$ for any $\delta>0$. We describe as well the main features of a
numerical scheme for approximating $\mathbf{u}_V$ and $E(\mathbf{u}_V)$ and
give a numerical example for the case of a stored energy for an elastic fluid.


title:
Nonlinear tides in a homogeneous rotating planet or star: global modes
  and elliptical instability

abstract:
  We revisit the global modes and instabilities of homogeneous rotating
ellipsoidal fluid masses, which are the simplest global models of rotationally
and tidally deformed gaseous planets or stars. The tidal flow in a short-period
planet may be unstable to the elliptical instability, a hydrodynamic
instability that can drive tidal evolution. We perform a global (and local WKB)
analysis to study this instability using the elegant formalism of Lebovitz &
Lifschitz. We survey the parameter space of global instabilities with harmonic
orders $\ell\leq 5$, for planets with spins that are purely aligned (prograde)
or anti-aligned (retrograde) with their orbits. In general, the instability has
a much larger growth rate if the planetary spin and orbit are anti-aligned
rather than aligned. We have identified a violent instability for anti-aligned
spins outside of the usual frequency range for the elliptical instability (when
$\frac{n}{\Omega}\lesssim -1$, where $n$ and $\Omega$ are the orbital and spin
angular frequencies, respectively) if the tidal amplitude is sufficiently
large. We also explore the instability in a rigid ellipsoidal container, which
is found to be quantitatively similar to that with a realistic free surface.
Finally, we study the effect of rotation and tidal deformation on mode
frequencies. We find that larger rotation rates and larger tidal deformations
both decrease the frequencies of the prograde sectoral surface gravity modes.
This increases the prospect of their tidal excitation, potentially enhancing
the tidal response over expectations from linear theory. In a companion paper,
we use our results to interpret global simulations of the elliptical
instability.

categories: astro-ph.EP astro-ph.HE astro-ph.SR physics.flu-dyn


title:
Nonlinear tides in a homogeneous rotating planet or star: global
  simulations of the elliptical instability

abstract:
  I present results from the first global hydrodynamical simulations of the
elliptical instability in a tidally deformed gaseous planet (or star) with a
free surface. The elliptical instability is potentially important for tidal
evolution of the shortest-period hot Jupiters. I model the planet as a
spin-orbit aligned or anti-aligned, and non-synchronously rotating, tidally
deformed, homogeneous fluid body. A companion paper presented an analysis of
the global modes and instabilities of such a planet. Here I focus on the
nonlinear evolution of the elliptical instability. This is observed to produce
bursts of turbulence that drive the planet towards synchronism with its orbit
in an erratic manner. If the planetary spin is initially anti-aligned, the
elliptical instability also drives spin-orbit alignment on a similar timescale
as the spin synchronisation. The instability generates differential rotation
inside the planet in the form of zonal flows, which play an important role in
the saturation of the instability, and in producing the observed burstiness.
These results are broadly consistent with the picture obtained using a local
Cartesian model (where columnar vortices played the role of zonal flows). I
also simulate the instability in a container that is rigid (but stress-free)
rather than free, finding broad quantitative agreement. The dissipation
resulting from the elliptical instability could explain why the shortest-period
hot Jupiters tend to have circular orbits inside about 2-3 days, and predicts
spin-synchronisation (and spin-orbit alignment) out to about 10-15 days.
However, other mechanisms must be invoked to explain tidal circularisation for
longer orbital periods.


title: Atmospheric Neutrinos: Status and Prospects

abstract:
  We present an overview of the current status of neutrino oscillation studies
at atmospheric neutrino experiments. While the current data gives some
tentalising hints regarding the neutrino mass hierarchy, octant of
$\theta_{23}$ and $\delta_{CP}$, the hints are not statistically significant.
We summarise the sensitivity to these sub-dominant three-generation effects
from the next-generation proposed atmospheric neutrino experiments. We next
present the prospects of new physics searches such as non-standard
interactions, sterile neutrinos and CPT violation studies at these experiments.


title: Role of spd- Continuum Components in the Halo Nucleus 6He

abstract:
  Role of different continuum components in the weakly bound nucleus 6He is
studied by coupling unbound spd-waves of 5He by using simple pairing
contact-delta interaction. The results show that 6He ground state $0^+$
displays collective nature by taking contribution from five different
oscillating continuum states that sum up to give an exponentially decaying
bound wavefunction emerging from five different possible configurations i.e.
$(s_{1/2})^2$, $(p_{1/2})^2$, $(p_{3/2})^2$, $(d_{3/2})^2$ and $(d_{5/2})^2$.
The ground state properties of 6He has been calculated.


title: Variational Methods For Phononic Calculations

abstract:
  Three fundamental variational principles used for solving elastodynamic
eigenvalue problems are studied within the context of elastic wave propagation
in periodic composites (phononics). We study the convergence of the eigenvalue
problems resulting from the displacement Rayleigh quotient, the stress Rayleigh
quotient and the mixed quotient. The convergence rates of the three quotients
are found to be related to the continuity and differentiability of the density
and compliance variation over the unit cell. In general, the mixed quotient
converges faster than both the displacement Rayleigh and the stress Rayleigh
quotients, however, there exist special cases where either the displacement
Rayleigh or the stress Rayleigh quotient shows the exact same convergence as
the mixed-method. We show that all methods converge faster for smoother
material property variations, but when density variation is rough, the
difference between the mixed quotient and stress Rayleigh quotient is higher
and similarly, when compliance variation is rough, the difference between the
mixed quotient and displacement Rayleigh quotient is higher. Since eigenvalue
problems such as those considered in this paper tend to be highly
computationally intensive, it is expected that these results will lead to fast
and efficient algorithms in the areas of phononics and photonics.


title: A Decision Procedure for Separation Logic in SMT

abstract:
  This paper presents a complete decision procedure for the entire
quantifier-free fragment of Separation Logic ($\seplog$) interpreted over
heaplets with data elements ranging over a parametric multi-sorted (possibly
infinite) domain. The algorithm uses a combination of theories and is used as a
specialized solver inside a DPLL($T$) architecture. A prototype was implemented
within the CVC4 SMT solver. Preliminary evaluation suggests the possibility of
using this procedure as a building block of a more elaborate theorem prover for
SL with inductive predicates, or as back-end of a bounded model checker for
programs with low-level pointer and data manipulations.


title:
Strongly Anisotropic Thermal and Electrical Conductivities of
  Self-assembled Silver Nanowire Network

abstract:
  Heat dissipation issues are the emerging challenges in the field of flexible
electronics. Thermal management of flexible electronics creates a demand for
flexible materials with highly anisotropic thermal conductivity, which work as
heat spreaders to remove excess heat in the in-plane direction and as heat
shields to protect human skin or device components under them from heating.
This study proposes a self-assembled silver nanowire network with high thermal
and electrical anisotropy with the potential to solve these challenges. The
in-plane thermal conductivity of the network along the axial direction of
silver nanowires is measured as 37 W/m-K while the cross-plane thermal
conductivity is only 0.36 W/m-K. The results of measurements of electrical and
thermal conductivities suggest that abundant wire-wire contacts strongly impede
thermal transport. The excellent alignment of nanowires results in the same
anisotropy ratio of 3 for both thermal and electrical conduction in the two
in-plane directions. The ratio remains unchanged as the temperature decrease to
50 K, which indicates that wire-wire contacts lower the thermal and electrical
conduction in the two directions to the same extent and their effect is
independent of temperature. In addition, phonon softening markedly reduces the
Debye temperatures of the network, which are fitted from the electrical
resistivity data. As a result of phonon thermal conduction, the Lorenz numbers
of the film in the two directions, which are approximately the same, are larger
than the Sommerfeld value at room temperature and decrease as temperature
decreases because of small angle scattering and the reduced phonon
contribution. This nanowire network provides a solution to the emerging
challenges of thermal management of flexible electronics.


title: A new class of metrics for learning on real-valued and structured data

abstract:
  We propose a new class of metrics on sets, vectors, and functions that can be
used in various stages of data mining, including exploratory data analysis,
learning, and result interpretation. These new distance functions unify and
generalize some of the popular metrics, such as the Jaccard and bag distances
on sets, Manhattan distance on vector spaces, and Marczewski-Steinhaus distance
on integrable functions. We prove that the new metrics are complete and show
useful relationships with $f$-divergences for probability distributions. To
further extend our approach to structured objects such as concept hierarchies
and ontologies, we introduce information-theoretic metrics on directed acyclic
graphs drawn according to a fixed probability distribution. We conduct
empirical investigation to demonstrate intuitive interpretation of the new
metrics and their effectiveness on real-valued, high-dimensional, and
structured data. Extensive comparative evaluation demonstrates that the new
metrics outperformed multiple similarity and dissimilarity functions
traditionally used in data mining, including the Minkowski family, the
fractional $L^p$ family, two $f$-divergences, cosine distance, and two
correlation coefficients. Finally, we argue that the new class of metrics is
particularly appropriate for rapid processing of high-dimensional and
structured data in distance-based learning.


title: Coupled transport in rotor models

abstract:
  Steady non-equilibrium states are investigated in a one-dimensional setup in
the presence of two thermodynamic currents. Two paradigmatic nonlinear
oscillators models are investigated: an XY chain and the discrete nonlinear
Schr\"odinger equation. Their distinctive feature is that the relevant variable
is an angle in both cases. We point out the importance of clearly
distinguishing between energy and heat flux. In fact, even in the presence of a
vanishing Seebeck coefficient, a coupling between (angular) momentum and energy
arises, mediated by the unavoidable presence of a "coherent" energy flux. Such
a contribution is the result of the "advection" induced by the
position-dependent angular velocity. As a result, in the XY model, the
knowledge of the two diagonal elements of the Onsager matrix suffices to
reconstruct its transport properties. The analysis of the nonequilibrium steady
states finally allows to strengthen the connection between the two models.


title: Report on Dirty Paper Coding Estimation with multidimensional lattices

abstract:
  In this report we include some derivations on a channel estimation method
based on the use of Dirty Paper Coding. Specifically, we analyze the proposed
method, named Dirty Paper-based Channel Estimation (DPCE), when the considered
codebooks are high-dimensional lattices.


title: Statistical Uncertainty in Quantitative Neutron Radiography

abstract:
  We demonstrate a novel procedure to calibrate neutron detection systems
commonly used in standard neutron radiography. This calibration allows
determining the uncertainties due to Poisson-like neutron counting statistics
for each individual pixel of a radiographic image. The obtained statistical
errors are necessary in order to perform a correct quantitative analysis. This
fast and convenient method is applied to data measured at the cold neutron
radiography facility ICON at the Paul Scherrer Institute. Moreover, from the
results the effective neutron flux at the beam line is determined.


title: Array Folds Logic

abstract:
  We present an extension to the quantifier-free theory of integer arrays which
allows us to express counting. The properties expressible in Array Folds Logic
(AFL) include statements such as "the first array cell contains the array
length," and "the array contains equally many minimal and maximal elements."
These properties cannot be expressed in quantified fragments of the theory of
arrays, nor in the theory of concatenation. Using reduction to counter
machines, we show that the satisfiability problem of AFL is PSPACE-complete,
and with a natural restriction the complexity decreases to NP. We also show
that adding either universal quantifiers or concatenation leads to
undecidability.
  AFL contains terms that fold a function over an array. We demonstrate that
folding, a well-known concept from functional languages, allows us to concisely
summarize loops that count over arrays, which occurs frequently in real-life
programs. We provide a tool that can discharge proof obligations in AFL, and we
demonstrate on practical examples that our decision procedure can solve a broad
range of problems in symbolic testing and program verification.


title:
Continuity, positivity and simplicity of the Lyapunov exponents for
  quasi-periodic cocycles

abstract:
  An analytic quasi-periodic cocycle is a linear cocycle over a fixed ergodic
torus translation of one or several variables, where the fiber action depends
analytically on the base point. Consider the space of all such cocycles of any
given dimension and endow it with the uniform norm. Assume that the translation
vector satisfies a generic Diophantine condition. We prove large deviation type
estimates for the iterates of such cocycles, which, moreover, are stable under
small perturbations of the cocycle. As a consequence of these uniform
estimates, we establish continuity properties of the Lyapunov exponents
regarded as functions on this space of cocycles. This result builds upon our
previous work on this topic and its proof uses an abstract continuity theorem
of the Lyapunov exponents which we derived in a recent monograph. The new
feature of this paper is extending the availability of such results to cocycles
that are identically singular (i.e. non-invertible anywhere), in the several
variables torus translation setting. This feature is exactly what allows us,
through a simple limiting argument, to obtain criteria for the positivity and
simplicity of the Lyapunov exponents of such cocycles. Specializing to the
family of cocycles corresponding to a block Jacobi operator, we derive
consequences on the continuity, positivity and simplicity of its Lyapunov
exponents, and on the continuity of its integrated density of states.


title: Unique continuation for the Schr\"odinger equation with gradient term

abstract:
  We obtain a unique continuation result for the differential inequality $|
(i\partial_t +\Delta)u | \leq |Vu| + | W\cdot\nabla u |$ by establishing $L^2$
Carleman estimates. Here, $V$ is a scalar function and $W$ is a vector
function, which may be time-dependent or time-independent. As a consequence, we
give a similar result for the magnetic Schr\"odinger equation.


title:
A new proof for the existence of degree bounds for Putinar's
  Positivstellensatz

abstract:
  Putinar's Positivstellensatz is a central theorem in real algebraic geometry.
It states the following: If you have a set $S= \{ x \in R^n \ | \ g_1 (x) \geq
0, ... , g_m(x) \geq 0\}$ described by some real polynomials $g_i$, then every
real polynomial $f$ that is positive on $S$ can be written as a sum of squares
weighted by the $g_i$ and $1$. Consider such an identity $f= \sum_{i=1}^{m} g_i
s_i + s_0$. For the applications in polynomial optimization, especially
semidefinite programming, the following is important:
  There exists a bound $N$ for the degrees of the $s_i$ which depends only on
the $g_i$, $n$, the degree of $f$, an upper bound for $||f||$ and a lower bound
for $\min f(S)$.
  Two proofs from Prestel and He{\ss} resp. Schweighofer and Nie ([Pr], [He]
resp. [Sw], [NS]) for the existence of these degree bounds are known (also for
the matrix version of Putinar's Positivstellensatz by Helton and Nie [HN]).
Prestel uses valuation and model theory for his approach while Schweighofer
gives a constructive solution by using a theorem of P\'{o}lya.
  In this paper we will give a new elementary, short but non-constructive
proof.


title: On the number of saddle connections in translation surfaces with poles

abstract:
  Translation surfaces with poles correspond to meromorphic differentials on
compact Riemann surfaces. They appear in compactifications of strata of the
moduli space of Abelian differentials and in the study of stability conditions.
Such structures have different geometrical and dynamical properties than usual
translation surfaces. In particular, they always have infinite area and can
have a finite number of saddle connections. We provide a combinatorial
characterization of the strata for which there can be an infinite number of
saddle connections and give lower and upper bounds for the number of saddle
connections and related quantities.


title: 3-D phononic crystals with ultra-wide band gaps

abstract:
  In this paper gradient based topology optimization (TO) is used to discover
3-D phononic structures that exhibit ultra-wide normalized all-angle all-mode
band gaps. The challenging computational task of repeated 3-D phononic
band-structure evaluations is accomplished by a combination of a fast mixed
variational eigenvalue solver and distributed Graphic Processing Unit (GPU)
parallel computations. The TO algorithm utilizes the material
distribution-based approach and a gradient-based optimizer. The design
sensitivity for the mixed variational eigenvalue problem is derived using the
adjoint method and is implemented through highly efficient vectorization
techniques. We present optimized results for two-material simple cubic (SC),
body centered cubic (BCC), and face centered cubic (FCC) crystal structures and
show that in each of these cases different initial designs converge to single
inclusion network topologies within their corresponding primitive cells. The
optimized results show that large phononic stop bands for bulk wave propagation
can be achieved at lower than close packed spherical configurations leading to
lighter unit cells. For tungsten carbide - epoxy crystals we identify all angle
all mode normalized stop bands exceeding 100%, which is larger than what is
possible with only spherical inclusions.


title:
Removing grain boundaries from three-dimensional colloidal crystals
  using active dopants

abstract:
  Using computer simulations we explore how grain boundaries can be removed
from three-dimensional colloidal crystals by doping with a small fraction of
active colloids. We show that for sufficient self-propulsion, the system is
driven into a crystal-fluid coexistence. In this phase separated regime, the
active dopants become mobile and spontaneously gather at the grain boundaries.
The resulting surface melting and recrystallization of domains result in the
motion of the grain boundaries over time and lead to the formation of a large
single crystal. However, when the self-propulsion is too low to cause a phase
separation, we observe no significant enhancement of grain growth.


title: Unity-Efficiency Parametric Down-Conversion via Amplitude Amplification

abstract:
  We propose an optical scheme, employing optical parametric down-converters
interlaced with nonlinear sign gates (NSGs), that completely converts an
$n$-photon Fock-state pump to $n$ signal-idler photon pairs when the
down-converters' crystal lengths are chosen appropriately. The proof of this
assertion relies on amplitude amplification, analogous to that employed in
Grover search, applied to the full quantum dynamics of single-mode parametric
down-conversion. When we require that all Grover iterations use the same
crystal, and account for potential experimental limitations on crystal-length
precision, our optimized conversion efficiencies reach unity for $1\le n \le
5$, after which they decrease monotonically for $n$ values up to 50, which is
the upper limit of our numerical dynamics evaluations. Nevertheless, our
conversion efficiencies remain higher than those for a conventional (no NSGs)
down-converter.


title: The Theory of Spin Noise Spectroscopy: A Review

abstract:
  Direct measurements of spin fluctuations are becoming the mainstream approach
for studies of complex condensed matter, molecular, nuclear, and atomic
systems. This review covers recent progress in the field of optical Spin Noise
Spectroscopy (SNS) with an additional goal to establish an introduction into
its theoretical foundations. Various theoretical techniques that have been
recently used to interpret results of SNS measurements are explained alongside
with examples of their applications.


title: Enhanced perceptrons using contrastive biclusters

abstract:
  Perceptrons are neuronal devices capable of fully discriminating linearly
separable classes. Although straightforward to implement and train, their
applicability is usually hindered by non-trivial requirements imposed by
real-world classification problems. Therefore, several approaches, such as
kernel perceptrons, have been conceived to counteract such difficulties. In
this paper, we investigate an enhanced perceptron model based on the notion of
contrastive biclusters. From this perspective, a good discriminative bicluster
comprises a subset of data instances belonging to one class that show high
coherence across a subset of features and high differentiation from nearest
instances of the other class under the same features (referred to as its
contrastive bicluster). Upon each local subspace associated with a pair of
contrastive biclusters a perceptron is trained and the model with highest area
under the receiver operating characteristic curve (AUC) value is selected as
the final classifier. Experiments conducted on a range of data sets, including
those related to a difficult biosignal classification problem, show that the
proposed variant can be indeed very useful, prevailing in most of the cases
upon standard and kernel perceptrons in terms of accuracy and AUC measures.


title:
Tracing jet emission at the base of a high-mass YSO. First AMBER/VLTI
  observations of the Br\gamma emission in IRAS 13481-6124

abstract:
  To probe the circumstellar environment of IRAS 13481-6124, a 20 M_sun
high-mass young stellar object (HMYSO) with a parsec-scale jet and accretion
disc, we investigate the origin of its Br\gamma-emission line through NIR
interferometry. We present the first AMBER/VLTI observations of the
Br\gamma-emitting region in an HMYSO at R~1500. Our AMBER/VLTI observations
reveal a spatially and spectrally resolved Br\gamma-line in emission with a
strong P Cygni profile, indicating outflowing matter with a terminal velocity
of ~500 km/s. Visibilities, differential phases, and closure phases are
detected in our observations within the spectral line and in the adjacent
continuum. Both total visibilities (continuum plus line emitting region) and
pure-line visibilities indicate that the Br\gamma-emitting region is more
compact (2-4 mas in diameter or ~6-13 au at 3.2 kpc) than the
continuum-emitting region (~5.4 mas or ~17 au). The absorption feature is also
spatially resolved at the longest baselines (81 and 85 m) and has a visibility
that is slightly smaller than the continuum-emitting region. The differential
phases at the four longest baselines display an \u2018S\u2019-shaped structure
across the line, peaking in the blue- and red-shifted high-velocity components.
The calibrated photocentre shifts are aligned with the known jet axis, i.e they
are probably tracing an ionised jet. The high-velocity components (v_r~100-500
km/s) are located far from the source, whereas the low-velocity components
(0-100 km/s) are observed to be closer, indicating a strong acceleration of the
gas flow in the inner 10 au. Finally, a non-zero closure phase along the
continuum is detected. By comparing our observations with the synthetic images
of the continuum around 2.16 um, we confirm that this feature originates from
the asymmetric brightness distribution of the continuum owing to the
inclination of the inner disc.


title: Trading-off variance and complexity in stochastic gradient descent

abstract:
  Stochastic gradient descent is the method of choice for large-scale machine
learning problems, by virtue of its light complexity per iteration. However, it
lags behind its non-stochastic counterparts with respect to the convergence
rate, due to high variance introduced by the stochastic updates. The popular
Stochastic Variance-Reduced Gradient (SVRG) method mitigates this shortcoming,
introducing a new update rule which requires infrequent passes over the entire
input dataset to compute the full-gradient.
  In this work, we propose CheapSVRG, a stochastic variance-reduction
optimization scheme. Our algorithm is similar to SVRG but instead of the full
gradient, it uses a surrogate which can be efficiently computed on a small
subset of the input data. It achieves a linear convergence rate ---up to some
error level, depending on the nature of the optimization problem---and features
a trade-off between the computational complexity and the convergence rate.
Empirical evaluation shows that CheapSVRG performs at least competitively
compared to the state of the art.


title:
Single- and Few-Layer WTe2 and Their Suspended Nanostructures: Raman
  Signatures and Nanomechanical Resonances

abstract:
  Single crystal tungsten ditelluride (WTe2) has recently been discovered to
exhibit non-saturating extreme magnetoresistance in bulk; it has also emerged
as a new layered material from which atomic layer crystals can be extracted.
While atomically thin WTe2 is attractive for its unique properties, little
study has been conducted on single- and few-layer WTe2. Here we report the
isolation of single- and few-layer WTe2, as well as fabrication and
characterization of the first WTe2 suspended nanostructures. We have observed
new Raman signatures of few-layer WTe2 that have been theoretically predicted
but not yet reported to date, in both on-substrate and suspended WTe2 flakes.
We have further probed the nanomechanical properties of suspended WTe2
structures by measuring their flexural resonances, and obtain a Young's modulus
of E_Y~80GPa for the suspended WTe2 flakes. This study paves the way for future
investigations and utilization of the multiple new Raman fingerprints of
single- and few-layer WTe2, and for exploring mechanical control of WTe2 atomic
layers.


title: A universal linear algebraic model for conformal geometries

abstract:
  This article describes an entirely algebraic construction for developing
conformal geometries, which provide models for, among others, the Euclidean,
spherical and hyperbolic geometries. On one hand, their relationship is usually
shown analytically, through a framework comparing the measurement of distances
and angles in Cayley-Klein geometries, including Lorentzian geometries, as done
by F. Bachmann and later R. Struve. On the other hand, such a relationship may
also be expressed in a purely linear algebraic manner, as explained by D.
Hestens, H. Li and A. Rockwood.
  The model described in this article unifies these approaches via a
generalization of Lie sphere geometry. Like the work of N. Wildberger, it is a
purely algebraic construction, and as such it works over any field of odd
characteristic. It is shown that measurement of distances and angles is an
inherent property of the model that is easy to identify, and the possible
models are classified over the real, complex and finite fields, and partially
in characteristic $2$, revealing a striking analogy between the real and finite
geometries.


title:
Evidence for a new symmetry breaking mechanism reorienting quantum Hall
  nematics

abstract:
  We report on the effect of in-plane magnetic field $B_\parallel$ on stripe
phases in higher ($N=2,3$) Landau levels of a high-mobility 2D electron gas. In
accord with previous studies, we find that a modest $B_\parallel$ applied
parallel to the native stripes aligns them perpendicular to it. However, upon
further increase of $B_\parallel$, stripes are reoriented back to their native
direction. Remarkably, applying $B_\parallel$ perpendicular to the native
stripes also aligns stripes parallel to it. Thus, regardless of the initial
orientation of stripes with respect to $B_\parallel$, stripes are ultimately
aligned \emph{parallel} to $B_\parallel$. These findings provide evidence for a
$B_\parallel$-induced symmetry breaking mechanism which challenge current
understanding of the role of $B_\parallel$ and should be taken into account
when determining the strength of the native symmetry breaking potential.
Finally, our results might indicate nontrivial coupling between the native and
external symmetry breaking fields, which has not yet been theoretically
considered.


title: Landweber flat real pairs and ER(n)-cohomology

abstract:
  We take advantage of the internal algebraic structure of the Bockstein
spectral sequence converging to ER(n)^*(pt) to prove that for spaces Z that are
part of Landweber flat real pairs with respect to E(n), the cohomology ring
ER(n)^*(Z) can be obtained from E(n)^*(Z) by base change. In particular, our
results allow us to compute the Real Johnson-Wilson cohomology of the
Eilenberg-MacLane spaces Z = K(Z, 2m+1), K(Z/2^q, 2m), K(Z/2, m) for all
natural numbers $m$ and $q$, as well as connective covers of BO: BO, BSO,
BSpin, and BO<8> (the last for n<3 only).


title:
Using graphical and pictorial representations to teach introductory
  astronomy students about the detection of extrasolar planets via
  gravitational microlensing

abstract:
  The detection and study of extrasolar planets is an exciting and thriving
field in modern astrophysics, and an increasingly popular topic in introductory
astronomy courses. One detection method relies on searching for stars whose
light has been gravitationally microlensed by an extrasolar planet. In order to
facilitate instructors' abilities to bring this interesting mix of general
relativity and extrasolar planet detection into the introductory astronomy
classroom, we have developed a new Lecture-Tutorial, "Detecting Exoplanets with
Gravitational Microlensing." In this paper, we describe how this new
Lecture-Tutorial's representations of astrophysical phenomena, which we
selected and created based on theoretically motivated considerations of their
pedagogical affordances, are used to help introductory astronomy students
develop more expert-like reasoning abilities.


title:
Pauli Decomposition over Commuting Subsets: Applications in Gate
  Synthesis, State Preparation, and Quantum Simulations

abstract:
  A key task in quantum computation is the application of a sequence of gates
implementing a specific unitary operation. However, the decomposition of an
arbitrary unitary operation into simpler quantum gates is a nontrivial problem.
Here we propose a general and robust protocol to decompose any target unitary
into a sequence of Pauli rotations. The procedure involves identifying a
commuting subset of Pauli operators having a high trace overlap with the target
unitary, followed by a numerical optimization of their corresponding rotation
angles. The protocol is demonstrated by decomposing several standard quantum
operations. The applications of the protocol for quantum state preparation and
quantum simulations are also described. Finally, we describe an NMR experiment
implementing a three-body quantum simulation, wherein the above decomposition
technique is used for the efficient realization of propagators.


title:
Charge and spin dynamics driven by ultrashort extreme broadband pulses:
  a theory perspective

abstract:
  This article gives an overview on recent theoretical progress in controlling
the charge and spin dynamics in low-dimensional electronic systems by means of
ultrashort and ultrabroadband electromagnetic pulses. A particular focus is put
on sub-cycle and single-cycle pulses and their utilization for coherent
control. The discussion is mostly limited to cases where the pulse duration is
shorter than the characteristic time scales associated with the involved
spectral features of the excitations. We work out that the pulse action amounts
in essence to a quantum map between the quantum states of the system at an
appropriately chosen time moment during the pulse. The influence of a
particular pulse shape on the post-pulse dynamics is reduced to several
integral parameters entering the expression for the quantum map. The validity
range of this reduction scheme for different strengths of the driving fields is
established and discussed for particular nanostructures. Acting with a periodic
pulse sequence, it is shown how the system can be steered to and largely
maintained in predefined states. The conditions for this nonequilibrium
sustainability are worked out by means of geometric phases, which are
identified as the appropriate quantities to indicate quasistationarity of
periodically driven quantum systems. Demonstrations are presented for the
control of the charge, spin, and valley degrees of freedom in nanostructures on
picosecond and subpicosecond time scales. The theory is illustrated with
several applications to one-dimensional semiconductor quantum wires and
superlattices, double quantum dots, semiconductor and graphene quantum rings.
Furthermore, we consider the response of strongly correlated systems to short
broadband pulses and show that this case bears a great potential to unveil high
order correlations while they build up upon excitations.

categories: cond-mat.mes-hall cond-mat.str-el physics.atm-clus quant-ph


title: The minimal length and the Shannon entropic uncertainty relation

abstract:
  In the framework of the generalized uncertainty principle, the position and
momentum operators obey the modified commutation relation
$[X,P]=i\hbar\left(1+\beta P^2\right)$ where $\beta$ is the deformation
parameter. Since the validity of the uncertainty relation for the Shannon
entropies proposed by Beckner, Bialynicki-Birula, and Mycieslki (BBM) depends
on both the algebra and the used representation, we show that using the
formally self-adjoint representation, i.e., $X=x$ and
$P=\tan\left(\sqrt{\beta}p\right)/\sqrt{\beta}$ where $[x,p]=i\hbar$, the BBM
inequality is still valid in the form $S_x+S_p\geq1+\ln\pi$ as well as in
ordinary quantum mechanics. We explicitly indicate this result for the harmonic
oscillator in the presence of the minimal length.


title:
The Value of Privacy: Strategic Data Subjects, Incentive Mechanisms and
  Fundamental Limits

abstract:
  We study the value of data privacy in a game-theoretic model of trading
private data, where a data collector purchases private data from strategic data
subjects (individuals) through an incentive mechanism. The private data of each
individual represents her knowledge about an underlying state, which is the
information that the data collector desires to learn. Different from most of
the existing work on privacy-aware surveys, our model does not assume the data
collector to be trustworthy. Then, an individual takes full control of its own
data privacy and reports only a privacy-preserving version of her data.
  In this paper, the value of $\epsilon$ units of privacy is measured by the
minimum payment of all nonnegative payment mechanisms, under which an
individual's best response at a Nash equilibrium is to report the data with a
privacy level of $\epsilon$. The higher $\epsilon$ is, the less private the
reported data is. We derive lower and upper bounds on the value of privacy
which are asymptotically tight as the number of data subjects becomes large.
Specifically, the lower bound assures that it is impossible to use less amount
of payment to buy $\epsilon$ units of privacy, and the upper bound is given by
an achievable payment mechanism that we designed. Based on these fundamental
limits, we further derive lower and upper bounds on the minimum total payment
for the data collector to achieve a given learning accuracy target, and show
that the total payment of the designed mechanism is at most one individual's
payment away from the minimum.


title: Cops, Robber and Medianwidth Parameters

abstract:
  In previous work, we introduced median decompositions, a generalisation of
tree decompositions where a graph can be modelled after any median graph, along
with a hierarchy of $i$-medianwidth parameters $(mw_i)_{i\geq 1}$ starting from
treewidth and converging to the clique number.
  We introduce another graph parameter based on the concept of median
decompositions, to be called $i$-latticewidth and denoted by $lw_i$, for which
we restrict the modelling median graph of a decomposition to be isometrically
embeddable into the Cartesian product of $i$ paths. The sequence $(lw_i)_{i\geq
1}$ gives rise to a hierarchy of parameters starting from pathwidth and
converging to the clique number. We characterise the $i$-latticewidth of a
graph in terms of maximal intersections of bags of $i$ path decompositions of
the graph.
  We study a generalisation of the classical Cops and Robber game, where the
robber plays against not just one, but $i$ cop players. Depending on whether
the robber is visible or not, we show a direct connection to $i$-medianwidth or
$i$-latticewidth, respectively.


title:
Building Model Identification during Regular Operation - Empirical
  Results and Challenges

abstract:
  The inter-temporal consumption flexibility of commercial buildings can be
harnessed to improve the energy efficiency of buildings, or to provide
ancillary service to the power grid. To do so, a predictive model of the
building's thermal dynamics is required. In this paper, we identify a
physics-based model of a multi-purpose commercial building including its
heating, ventilation and air conditioning system during regular operation. We
present our empirical results and show that large uncertainties in internal
heat gains, due to occupancy and equipment, present several challenges in
utilizing the building model for long-term prediction. In addition, we show
that by learning these uncertain loads online and dynamically updating the
building model, prediction accuracy is improved significantly.


title:
Combining plane wave expansion and variational techniques for fast
  phononic computations

abstract:
  In this paper the salient features of the Plane Wave Expansion (PWE) method
and the mixed variational technique are combined for the fast eigenvalue
computations of arbitrarily complex phononic unit cells. This is done by
expanding the material properties in a Fourier expansion, as is the case with
PWE. The required matrix elements in the variational scheme are identified as
the discrete Fourier transform coefficients of material properties, thus
obviating the need for any explicit integration. The process allows us to
provide succinct and closed form expressions for all the matrices involved in
the mixed variational method. The scheme proposed here preserves both the
simplicity of expression which is inherent in the PWE method and the superior
convergence properties of the mixed variational scheme. We present numerical
results and comment upon the convergence and stability of the current method.
We show that the current representation renders the results of the method
stable over the entire range of the expansion terms as allowed by the spatial
discretization. When compared with a zero order numerical integration scheme,
the present method results in greater computational accuracy of all
eigenvalues. A higher order numerical integration scheme comes close to the
accuracy of the present method but only with significantly more computational
expense.


title: The compatibility with the duality for partial Hasse invariants

abstract:
  We give a simple and natural proof for the compatibility of the Hasse
invariant with duality. We then study a $p$-divisible group with an action of
the ring of integers of a finite ramified extension of $\mathbb{Q}_p$. We
suppose that it satisfies the Pappas-Rapoport condition ; in that case the
Hasse invariant is a product of partial Hasse invariants, each of which can be
expressed in terms of primitive Hasse invariants. We then show that the dual of
the $p$-divisible group naturally satisfies a Pappas-Rapoport condition, and
prove the compatibility with the duality for the partial and primitive Hasse
invariants.


title: Preheating after technicolor inflation

abstract:
  We investigate the particle production due to parametric resonances in model
of inflation where the lightest composite state stemming from the minimal
walking technicolor theory plays the role of the inflaton. For model of
inflation, the effective theory couples non-minimally to gravity. Regarding the
preheating, we study in details a model of a composite inflaton field $\phi$
coupled to another scalar field $\chi$ with the interaction term
$g^{2}\phi^{2}\chi^{2}$. Particularly, in the Minkowski space, the stage of
parametric resonances can be described by the Mathieu equation. Interestingly,
we discover that broad resonances can be typically achieved and potentially
efficient in our model causing the number of particle density in this process
exponentially increases.


title:
The optical variability of SDSS quasars from multi-epoch spectroscopy.
  II. color variation

abstract:
  We investigated the optical/ultraviolet (UV) color variations for a sample of
2169 quasars based on multi-epoch spectroscopy in the Sloan Digital Sky Survey
(SDSS) data release seven (DR7) and data release nine (DR9). To correct the
systematic difference between DR7 and DR9 due to the different instrumental
setup, we produced a correction spectrum by using a sample of F-stars observed
both in DR7 and DR9. The correction spectrum was then applied to quasars when
comparing the spectra of DR7 with DR9. In each object, the color variation was
explored by comparing the spectral index of the continuum power-law fit on the
brightest spectrum with the faintest one, and also by the shape of their
difference spectrum. In 1876 quasars with consistent color variations from two
methods, we found that most sources (1755, $\sim 94\%$) show
bluer-when-brighter (BWB) trend, and the redder-when-brighter (RWB) trend is
only detected in 121 objects ($\sim 6\%$). The common BWB trend is supported by
the bluer composite spectrum constructed from bright spectra than that from
faint spectra, and also by the blue composite difference spectrum. The
correction spectrum is proved to be highly reliable by comparing the composite
spectrum from corrected DR9 and original DR7 spectra. Assuming that the
optical/UV variability is triggered by fluctuations, RWB trend can likely be
explained if the fluctuations occur firstly at outer disk region, and the inner
disk region has not fully responded yet when the fluctuation being propagated
inward. In contrast, the common BWB trend implies that the fluctuations are
likely more often happening firstly in inner disk region.


title:
On the Secrecy Capacity of the Broadcast Wiretap Channel with Limited
  CSI Feedback

abstract:
  In this paper, we investigate the problem of secure broadcasting over
block-fading channels with limited channel knowledge at the transmitter. More
particularly, we analyze the effect of having imperfect channel state
information (CSI) via a finite rate feedback on the throughput of a broadcast
channel where the transmission is intended for multiple legitimate receivers in
the presence of an eavesdropper. First, we partially characterize the ergodic
secrecy capacity of the system when the source broadcasts the same information
to all the receivers, i.e., common message transmission. Then, we look at the
independent messages case, where the transmitter broadcasts multiple
independent messages to the legitimate receivers. For this case, we present
lower and upper bounds on the ergodic secrecy sum-capacity. In both scenarios,
we show that the proposed lower and upper bounds coincide asymptotically as the
capacity of the feedback links becomes large, hence, fully characterizing the
secrecy capacity in this case.


title: Signed Link Analysis in Social Media Networks

abstract:
  Numerous real-world relations can be represented by signed networks with
positive links (e.g., trust) and negative links (e.g., distrust). Link analysis
plays a crucial role in understanding the link formation and can advance
various tasks in social network analysis such as link prediction. The majority
of existing works on link analysis have focused on unsigned social networks.
The existence of negative links determines that properties and principles of
signed networks are substantially distinct from those of unsigned networks,
thus we need dedicated efforts on link analysis in signed social networks. In
this paper, following social theories in link analysis in unsigned networks, we
adopt three social science theories, namely Emotional Information, Diffusion of
Innovations and Individual Personality, to guide the task of link analysis in
signed networks.


title: A Unifying Framework for the Identification of Motor Primitives

abstract:
  A long-standing hypothesis in neuroscience is that the central nervous system
accomplishes complex motor behaviors through the combination of a small number
of motor primitives. Many studies in the last couples of decades have
identified motor primitives at the kinematic, kinetic, and electromyographic
level, thus supporting modularity at different levels of organization in the
motor system. However, these studies relied on heterogeneous definitions of
motor primitives and on different algorithms for their identification. Standard
unsupervised learning algorithms such as principal component analysis,
independent component analysis, and non-negative matrix factorization, or more
advanced techniques involving the estimation of temporal delays of the relevant
mixture components have been applied. This plurality of algorithms has made
difficult to compare and interpret results obtained across different studies.
Moreover, how the different definitions of motor primitives relate to each
other has never been examined systematically. Here we propose a comprehensive
framework for the definition of different types of motor primitives and a
single algorithm for their identification. By embedding smoothness priors and
specific constraints in the underlying generative model, the algorithm can
identify many different types of motor primitives. We assessed the
identification performance of the algorithm both on simulated data sets, for
which the properties of the primitives and of the corresponding combination
parameters were known, and on experimental electromyographic and kinematic data
sets, collected from human subjects accomplishing goal-oriented and rhythmic
motor tasks. The identification accuracy of the new algorithm was typically
equal or better than the accuracy of other unsupervised learning algorithms
used previously for the identification of the same types of primitives.


title:
Numerical simulation and experimental study of PbWO4/EPDM and
  Bi2WO6/EPDM for the shielding of {\gamma}rays

abstract:
  The MCNP5 code was employed to simulate the {\gamma}ray shielding capacity of
tungstate composites. The experimental results were applied to verify the
applicability of the Monte Carlo program. PbWO4 and Bi2WO6 were prepared and
added into ethylene propylene diene monomer (EPDM) to obtain the composites,
which were tested in the {\gamma}ray shielding. Both the theoretical simulation
and experiments were carefully chosen and well designed. The results of the two
methods were found to be highly consistent. In addition, the conditions during
the numerical simulation were optimized and double-layer {\gamma}ray shielding
systems were studied. It was found that the {\gamma}-ray shielding performance
can be influenced not only by the material thickness ratio but also by the
arrangement of the composites.


title:
Feeling the Bern: Adaptive Estimators for Bernoulli Probabilities of
  Pairwise Comparisons

abstract:
  We study methods for aggregating pairwise comparison data in order to
estimate outcome probabilities for future comparisons among a collection of n
items. Working within a flexible framework that imposes only a form of strong
stochastic transitivity (SST), we introduce an adaptivity index defined by the
indifference sets of the pairwise comparison probabilities. In addition to
measuring the usual worst-case risk of an estimator, this adaptivity index also
captures the extent to which the estimator adapts to instance-specific
difficulty relative to an oracle estimator. We prove three main results that
involve this adaptivity index and different algorithms. First, we propose a
three-step estimator termed Count-Randomize-Least squares (CRL), and show that
it has adaptivity index upper bounded as $\sqrt{n}$ up to logarithmic factors.
We then show that that conditional on the hardness of planted clique, no
computationally efficient estimator can achieve an adaptivity index smaller
than $\sqrt{n}$. Second, we show that a regularized least squares estimator can
achieve a poly-logarithmic adaptivity index, thereby demonstrating a
$\sqrt{n}$-gap between optimal and computationally achievable adaptivity.
Finally, we prove that the standard least squares estimator, which is known to
be optimally adaptive in several closely related problems, fails to adapt in
the context of estimating pairwise probabilities.


title: Crystal dynamics and thermal properties of neptunium dioxide

abstract:
  We report an experimental and theoretical investigation of the lattice
dynamics and thermal properties of the actinide dioxide NpO$_2$. The
energy-wavevector dispersion relation for normal modes of vibration propagating
along the $[001]$, $[110]$, and $[111]$ high-symmetry lines in NpO$_2$ at room
temperature has been determined by measuring the coherent one-phonon scattering
of X-rays from a $\sim$1.2 mg single-crystal specimen, the largest available
single crystal for this compound. The results are compared against ab initio
phonon dispersions computed within the first-principles density functional
theory in the generalized gradient approximation plus Hubbard $U$ correlation
(GGA+$U$) approach, taking into account third-order anharmonicity effects in
the quasiharmonic approximation. Good agreement with the experiment is obtained
for calculations with an on-site Coulomb parameter $U = 4$ eV and Hund's
exchange $J= 0.6$ eV in line with previous electronic structure calculations.
We further compute the thermal expansion, heat capacity, thermal conductivity,
phonon linewidth, and thermal phonon softening, and compare with available
experiments. The theoretical and measured heat capacities are in close
agreement with another. About 27% of the calculated thermal conductivity is due
to phonons with energy higher than 25 meV ($\sim$ 6 THz ), suggesting an
important role of high-energy optical phonons in the heat transport. The
simulated thermal expansion reproduces well the experimental data up to about
1000 K, indicating a failure of the quasiharmonic approximation above this
limit.


title: Occupation time statistics of the random acceleration model

abstract:
  The random acceleration model is one of the simplest non-Markovian stochastic
systems and has been widely studied in connection with applications in physics
and mathematics. However, the occupation time and related properties are
non-trivial and not yet completely understood. In this paper we consider the
occupation time $T_+$ of the one-dimensional random acceleration model on the
positive half-axis. We calculate the first two moments of $T_+$ analytically
and also study the statistics of $T_+$ with Monte Carlo simulations. One goal
of our work was to ascertain whether the occupation time $T_+$ and the time
$T_m$ at which the maximum of the process is attained are statistically
equivalent. For regular Brownian motion the distributions of $T_+$ and $T_m$
coincide and are given by L\'evy's arcsine law. We show that for randomly
accelerated motion the distributions of $T_+$ and $T_m$ are quite similar but
not identical. This conclusion follows from the exact results for the moments
of the distributions and is also consistent with our Monte Carlo simulations.


title:
Kesten's incipient infinite cluster and quasi-multiplicativity of
  crossing probabilities

abstract:
  In this paper we consider Bernoulli percolation on an infinite connected
bounded degrees graph $G$. Assuming the uniqueness of the infinite open cluster
and a quasi-multiplicativity of crossing probabilities, we prove the existence
of Kesten's incipient infinite cluster. We show that our assumptions are
satisfied if $G$ is a slab $\mathbb Z^2\times\{0,\ldots,k\}^{d-2}$ ($d\geq 2$,
$k\geq 0$). We also argue that the quasi-multiplicativity assumption is
fulfilled for $G=\mathbb Z^d$ if and only if $d<6$.


title: SHELS: Complete Redshift Surveys of Two Widely Separated Fields

abstract:
  The SHELS (Smithsonian Hectospec Lensing Survey) is a complete redshift
survey covering two well-separated fields (F1 and F2) of the Deep Lens Survey.
Both fields are more than 94% complete to a Galactic extinction corrected R0 =
20.2. Here we describe the redshift survey of the F1 field centered at R.A. =
00h53m25.3s and Decl = 12d33m55s; like F2, the F1 field covers 4 sq deg. The
redshift survey of the F1 field includes 9426 new galaxy redshifts measured
with Hectospec on the MMT (published here). As a guide to future uses of the
combined survey we compare the mass metallicity relation and the distributions
of D4000 as a function of stellar mass and redshift for the two fields. The
mass-metallicity relations differ by an insignificant 1.6 sigma. For galaxies
in the stellar mass range 1.e10 to 1.e11 MSun, the increase in the star-forming
fraction with redshift is remarkably similar in the two fields. The seemingly
surprising 31-38% difference in the overall galaxy counts in F1 and F2 is
probably consistent with the expected cosmic variance given the subtleties of
the relative systematics in the two surveys. We also review the Deep Lens
Survey cluster detections in the two fields: poorer photometric data for F1
precluded secure detection of the single massive cluster at z = 0.35 that we
find in SHELS. Taken together the two fields include 16,055 redshifts for
galaxies with R0 <= 20.2 and 20,754 redshifts for galaxies with R <= 20.6.
These dense surveys in two well-separated fields provide a basis for future
investigations of galaxy properties and large-scale structure.


title: Reconstruction of Frequency Hopping Signals From Multi-Coset Samples

abstract:
  Multi-Coset (MC) sampling is a well established, practically feasible scheme
for sampling multiband analog signals below the Nyquist rate. MC sampling has
gained renewed interest in the Compressive Sensing (CS) community, due partly
to the fact that in the frequency domain, MC sampling bears a strong
resemblance to other sub-Nyquist CS acquisition protocols. In this paper, we
consider MC sampling of analog frequency hopping signals, which can be viewed
as multiband signals with changing band positions. This nonstationarity
motivates our consideration of a segment-based reconstruction framework, in
which the sample stream is broken into short segments for reconstruction. In
contrast, previous works focusing on the reconstruction of multiband signals
have used a segment-less reconstruction framework such as the modified MUSIC
algorithm. We outline the challenges associated with segment-based recovery of
frequency hopping signals from MC samples, and we explain how these challenges
can be addressed using conventional CS recovery techniques. We also demonstrate
the utility of the Discrete Prolate Spheroidal Sequences (DPSS's) as an
efficient dictionary for reducing the computational complexity of segment-based
reconstruction.


title: The First Time KE is Broken up

abstract:
  A relevant collection is a collection, $F$, of sets, such that each set in
$F$ has the same cardinality, $\alpha(F)$. A Konig Egervary (KE) collection is
a relevant collection $F$, that satisfies $|\bigcup F|+|\bigcap F|=2\alpha(F)$.
An hke (hereditary KE) collection is a relevant collection such that all of his
non-empty subsets are KE collections. In \cite{jlm} and \cite{dam}, Jarden,
Levit and Mandrescu presented results concerning graphs, that give the
motivation for the study of hke collections. In \cite{hke}, Jarden characterize
hke collections.
  Let $\Gamma$ be a relevant collection such that $\Gamma-\{S\}$ is an hke
collection, for every $S \in \Gamma$. We study the difference between $|\bigcap
\Gamma_1-\bigcup \Gamma_2|$ and $|\bigcap \Gamma_2-\bigcup \Gamma_1|$, where
$\{\Gamma_1,\Gamma_2\}$ is a partition of $\Gamma$. We get new
characterizations for an hke collection and for a KE graph.


title:
The behavioural aspect of green technology investments: a general
  positive model in the context of heterogeneous agents

abstract:
  Studies report that firms do not invest in cost-effective green technologies.
While economic barriers can explain parts of the gap, behavioural aspects cause
further under-valuation. This could be partly due to systematic deviations of
decision-making agents' perceptions from normative benchmarks, and partly due
to their diversity. This paper combines available behavioural knowledge into a
simple model of technology adoption. Firms are modelled as heterogeneous agents
with different behavioural responses. To quantify the gap, the model simulates
their investment decisions from different theoretical perspectives. While
relevant parameters are uncertain at the micro-level, using distributed agent
perspectives provides a realistic representation of the macro adoption rate.
The model is calibrated using audit data for proposed investments in energy
efficient electric motors. The inclusion of behavioural factors reduces
significantly expected adoption rates: from 81% using a normative optimisation
perspective, down to 20% using a behavioural perspective. The effectiveness of
various policies is tested.


title:
Correlation between peak energy and Fourier power density spectrum slope
  in gamma-ray bursts

abstract:
  The origin of the gamma-ray burst (GRB) prompt emission still defies
explanation, in spite of recent progress made, for example, on the occasional
presence of a thermal component in the spectrum along with the ubiquitous
non-thermal component that is modelled with a Band function. The combination of
finite duration and aperiodic modulations make GRBs hard to characterise
temporally. Although correlations between GRB luminosity and spectral hardness
on one side and time variability on the other side have long been known, the
loose and often arbitrary definition of the latter makes the interpretation
uncertain. We characterise the temporal variability in an objective way and
search for a connection with rest-frame spectral properties for a number of
well-observed GRBs. We studied the individual power density spectra (PDS) of
123 long gamma-ray bursts with measured redshift, rest-frame peak energy Ep,i
of the time-averaged nuFnu spectrum, and well-constrained PDS slope alpha
detected with Swift, Fermi and past spacecraft. The PDS were modelled with a
power law either with or without a break adopting a Bayesian Markov chain Monte
Carlo technique. We find a highly significant Ep,i-alpha anti-correlation. The
null hypothesis probability is ~ 10^-9. In the framework of the internal shock
synchrotron model, the Ep,i-alpha anti-correlation can hardly be reconciled
with the predicted Ep,i propto Gamma^-2, unless either variable microphysical
parameters of the shocks or continual electron acceleration are assumed.
Alternatively, in the context of models based on magnetic reconnection, the PDS
slope and Ep,i are linked to the ejecta magnetisation at the dissipation site,
so that more magnetised outflows would produce more variable GRB light curves
at short timescales (<= 1 s), shallower PDS, and higher values of Ep,i.


title: Individual power density spectra of Swift gamma-ray bursts

abstract:
  Timing analysis is a powerful tool with which to shed light on the still
obscure emission physics and geometry of the prompt emission of GRBs. Fourier
power density spectra (PDS) characterise time series as stochastic processes
and can be used to search for coherent pulsations and to investigate the
dominant variability timescales. Because of the limited duration and of the
statistical properties, modelling the PDS of individual GRBs is challenging,
and only average PDS of large samples have been discussed in the literature. We
characterise the individual PDS of GRBs in terms of a stochastic process, and
carry out for the first time a systematic search for periodic signals and for a
link between the PDS and other observables. We present a Bayesian procedure
that uses a Markov chain Monte Carlo technique and apply it to study 215 bright
long GRBs detected with the Swift Burst Alert Telescope from January 2005 to
May 2015. The PDS are modelled with a power-law either with or without a break.
Two classes of GRBs emerge: with or without a unique dominant timescale. A
comparison with active galactic nuclei (AGNs) reveals similar distributions of
PDS slopes. Unexpectedly, GRBs with subsecond-dominant timescales and duration
longer than a few tens of seconds in the source frame appear to be either very
rare or altogether absent. Three GRBs are found with possible evidence for a
periodic signal at ~3 sigma (Gaussian) significance, corresponding to a
multitrial chance probability of ~1%. Thus, we found no compelling evidence for
periodic signals. The analogy between the PDS of GRBs and of AGNs could
tentatively indicate similar stochastic processes that rule BH accretion across
different BH mass scales and objects. In addition, we find evidence that short
dominant timescales and duration are not completely independent of each other,
in contrast with commonly accepted paradigms (abridged).


title: Extended Main Sequence Turn-Offs in Low Mass Intermediate Age Clusters

abstract:
  We present an imaging analysis of four low mass stellar clusters (< 5000 Mo)
in the outer regions of the LMC in order to shed light on the extended main
sequence turn-off (eMSTO) phenomenon observed in high mass clusters. The four
clusters have ages between 1-2 Gyr and two of them appear to host eMTSOs. The
discovery of eMSTOs in such low mass clusters - > 5 times less massive than the
eMSTO clusters previously studied - suggests that mass is not the controlling
factor in whether clusters host eMSTOs. Additionally, the narrow extent of the
eMSTO in the two older (~ 2 Gyr) clusters is in agreement with predictions of
the stellar rotation scenario, as lower mass stars are expected to be
magnetically braked, meaning that their CMDs should be better reproduced by
canonical simple stellar populations. We also performed a structural analysis
on all the clusters and found that a large core radius is not a requisite for a
cluster to exhibit an eMSTO.


title:
Non-Equilibrium Phase Transition in an Atomistic Glassformer: the
  Connection to Thermodynamics

abstract:
  Tackling the low-temperature fate of supercooled liquids is challenging due
to the immense timescales involved, which prevent equilibration and lead to the
operational glass transition. Relating glassy behaviour to an underlying,
thermodynamic phase transition is a long-standing open question in condensed
matter physics. Like experiments, computer simulations are limited by the small
time window over which a liquid can be equilibrated. Here we address the
challenge of low temperature equilibration using trajectory sampling in a
system undergoing a nonequilibrium phase transition. This transition occurs in
trajectory space between the normal supercooled liquid and a glassy state rich
in low-energy geometric motifs. Our results indicate that this transition might
become accessible in equilibrium configurational space at a temperature close
to the so-called Kauzmann temperature, and provide a possible route to unify
dynamical and thermodynamical theories of the glass transition.


title: Moments of zeta and correlations of divisor-sums: IV

abstract:
  In this series we examine the calculation of the $2k$th moment and shifted
moments of the Riemann zeta-function on the critical line using long Dirichlet
polynomials and divisor correlations. The present paper begins the general
study of what we call Type II sums which utilize a circle method framework and
a convolution of shifted convolution sums to obtain all of the lower order
terms in the asymptotic formula for the mean square along $[T,2T]$ of a
Dirichlet polynomial of length up to $T^3$ with divisor functions as
coefficients.


title: Secure State Estimation for Nonlinear Power Systems under Cyber Attacks

abstract:
  This paper focuses on securely estimating the state of a nonlinear dynamical
system from a set of corrupted measurements. In particular, we consider two
broad classes of nonlinear systems, and propose a technique which enables us to
perform secure state estimation for such nonlinear systems. We then provide
guarantees on the achievable state estimation error against arbitrary
corruptions, and analytically characterize the number of errors that can be
perfectly corrected by a decoder. To illustrate how the proposed nonlinear
estimation approach can be applied to practical systems, we focus on secure
estimation for the wide area control of an interconnected power system under
cyber-physical attacks and communication failures, and propose a secure
estimator for the power system. Finally, we numerically show that the proposed
secure estimation algorithm enables us to reconstruct the attack signals
accurately.


title: A Selection of Giant Radio Sources from NVSS

abstract:
  Results of the application of pattern recognition techniques to the problem
of identifying Giant Radio Sources (GRS) from the data in the NVSS catalog are
presented and issues affecting the process are explored. Decision-tree pattern
recognition software was applied to training set source pairs developed from
known NVSS large angular size radio galaxies. The full training set consisted
of 51,195 source pairs, 48 of which were known GRS for which each lobe was
primarily represented by a single catalog component. The source pairs had a
maximum separation of 20 arc minutes and a minimum component area of 1.87
square arc minutes at the 1.4 mJy level. The importance of comparing resulting
probability distributions of the training and application sets for cases of
unknown class ratio is demonstrated. The probability of correctly ranking a
randomly selected (GRS, non-GRS) pair from the best of the tested classifiers
was determined to be 97.8 +/- 1.5%. The best classifiers were applied to the
over 870,000 candidate pairs from the entire catalog. Images of higher ranked
sources were visually screened and a table of over sixteen hundred candidates,
including morphological annotation, is presented. These systems include doubles
and triples, Wide-Angle Tail (WAT) and Narrow-Angle Tail (NAT), S- or Z-shaped
systems, and core-jets and resolved cores. While some resolved lobe systems are
recovered with this technique, generally it is expected that such systems would
require a different approach.