title:
Subarcsecond Bright Points and Quasi-periodic Upflows Below a Quiescent
  Filament Observed by the IRIS

abstract:
  Using UV spectra and SJIs from the IRIS, and coronal images and magnetograms
from the Solar Dynamics Observatory (SDO), we present the new features in a
quiescent filament channel: subarcsecond bright points (BPs) and quasi-periodic
upflows. The BPs in the TR have a spatial scale of about 350$-$580 km and
lifetime of more than several tens of minutes. They are located at stronger
magnetic structures in the filament channel, with magnetic flux of about
10$^{17}$$-$10$^{18}$ Mx. Quasi-periodic brightenings and upflows are observed
in the BPs and the period is about 4$-$5 min. The BP and the associated
jet-like upflow comprise a "tadpole-shaped" structure. The upflows move along
bright filament threads and their directions are almost parallel to the spine
of the filament. The upflows initiated from the BPs with opposite polarity
magnetic fields have opposite directions. The velocity of the upflows in plane
of sky is about 5$-$50 km s$^{-1}$. The emission line of Si IV 1402.77 {\AA} at
the locations of upflows exhibits obvious blueshifts of about 5$-$30 km
s$^{-1}$, and the line profile is broadened with the width of more than 20 km
s$^{-1}$. The BPs seem to be the bases of filament threads and the upflows are
able to convey mass for the dynamic balance of the filament. The
"counter-streaming" flows in previous observations may be caused by the
propagation of bi-directional upflows initiated from opposite polarity magnetic
fields. We suggest that quasi-periodic brightenings of BPs and quasi-periodic
upflows result from small-scale oscillatory magnetic reconnections, which are
modulated by solar p-mode waves.


title: Semiclassical Sobolev constants for the electro-magnetic Robin Laplacian

abstract:
  This paper is devoted to the asymptotic analysis of the optimal Sobolev
constants in the semiclassical limit and in any dimension. We combine
semiclassical arguments and concentration-compactness estimates to tackle the
case when an electromagnetic field is added as well as a smooth boundary
carrying a Robin condition. As a byproduct of the semiclassical strategy, we
also get exponentially weighted localization estimates of the minimizers.


title:
Dynamic structure factor of liquid 4He across the normal-superfluid
  transition

abstract:
  We have carried out a microscopic study of the dynamic structure factor of
liquid $^4$He across the normal-superfluid transition temperature using the
path integral Monte Carlo method. The ill-posed problem of the inverse Laplace
transform, from the imaginary-time intermediate scattering function to the
dynamic response, is tackled by stochastic optimization. Our results show a
quasi-particle peak and a small and broad multiphonon contribution. In spite of
the lack of strength in the collective peaks, we clearly identify the rapid
dropping of the roton peak amplitude when crossing the transition temperature
$T_\lambda$. Other properties such as the static structure factor, static
response, and one-phonon contribution to the response are also calculated at
different temperatures. The changes of the phonon-roton spectrum with the
temperature are also studied. An overall agreement with available experimental
data is achieved.


title: A toy model of black hole complementarity

abstract:
  We consider the algebra of simple operators defined in a time band in a CFT
with a holographic dual. When the band is smaller than the light crossing time
of AdS, an entire causal diamond in the center of AdS is separated from the
band by a horizon. We show that this algebra obeys a version of the
Reeh-Schlieder theorem: the action of the algebra on the CFT vacuum can
approximate any low energy state in the CFT arbitrarily well, but no operator
within the algebra can exactly annihilate the vacuum. We show how to relate
local excitations in the complement of the central diamond to simple operators
in the band. Local excitations within the diamond are invisible to the algebra
of simple operators in the band by causality, but can be related to complicated
operators called "precursors". We use the Reeh-Schlieder theorem to write down
a simple and explicit formula for these precursors on the boundary. We comment
on the implications of our results for black hole complementarity and the
emergence of bulk locality from the boundary.


title:
Using a Cloud Based Collaboration Technology in a Systems Analysis and
  Design Course

abstract:
  In order to effectively prepare the next generation of IT professionals and
systems analysts, it is important to incorporate cloud based online
collaboration tools into the coursework for developing the students'
cooperative skills as well as for storing and sharing content. For these
pedagogical and practical reasons, Google Drive has been used at a medium-sized
institution of higher education in New Zealand during the Systems Analysis and
Design course. Ongoing and successful use of any learning technology requires
gathering meaningful feedback from students, and acting as a mentor during
their learning journey. This study has been developed and implemented to help
students enjoy the collaborative technology and to help increase their
satisfaction and commitment. In order to overcome the obstacles that may
prevent students from using Google Drive optimally, an initial survey has been
conducted to better understand the influential factors and issues. Furthermore,
this study aims at promoting various types of collaboration and sharing: seeing
and learning from other students' work, receiving direct suggestions from
others, and allowing others to edit documents that belong to them. Following
the results of the first quantitative survey, numerous teaching strategies were
formulated and implemented. A final qualitative survey was done at the end of
the course for students to evaluate their project work. The results of this
study also provide original practical and theoretical implications that may be
of interest to other researchers, course designers, and teachers.


title:
Image Captioning and Visual Question Answering Based on Attributes and
  External Knowledge

abstract:
  Much recent progress in Vision-to-Language problems has been achieved through
a combination of Convolutional Neural Networks (CNNs) and Recurrent Neural
Networks (RNNs). This approach does not explicitly represent high-level
semantic concepts, but rather seeks to progress directly from image features to
text. In this paper we first propose a method of incorporating high-level
concepts into the successful CNN-RNN approach, and show that it achieves a
significant improvement on the state-of-the-art in both image captioning and
visual question answering. We further show that the same mechanism can be used
to incorporate external knowledge, which is critically important for answering
high level visual questions. Specifically, we design a visual question
answering model that combines an internal representation of the content of an
image with information extracted from a general knowledge base to answer a
broad range of image-based questions. It particularly allows questions to be
asked about the contents of an image, even when the image itself does not
contain a complete answer. Our final model achieves the best reported results
on both image captioning and visual question answering on several benchmark
datasets.


title:
Formation Mechanism of Guided Resonances and Bound States in the
  Continuum in Photonic Crystal Slabs

abstract:
  We develop a formalism, based on the mode expansion method, to describe the
guided resonances and bound states in the continuum (BICs) in photonic crystal
slabs with one-dimensional periodicity. This approach provides analytic
insights to the formation mechanisms of these states: the guided resonances
arise from the transverse Fabry-P\'erot condition, and the divergence of the
resonance lifetimes at the BICs is explained by a destructive interference of
radiation from different propagating components inside the slab. We show BICs
at the center and on the edge of the Brillouin zone protected by symmetry, as
well as BICs at generic wave vectors not protected by symmetry.


title:
Centrality dependence of $\mathbf{\psi}$(2S) suppression in p-Pb
  collisions at $\mathbf{\sqrt{{\textit s}_{\rm NN}}}$ = 5.02 TeV

abstract:
  The inclusive production of the $\psi$(2S) charmonium state was studied as a
function of centrality in p-Pb collisions at the nucleon-nucleon center of mass
energy $\sqrt{s_{\rm NN}}$ = 5.02 TeV at the CERN LHC. The measurement was
performed with the ALICE detector in the center of mass rapidity ranges
$-4.46<y_{\rm cms}<-2.96$ and $2.03<y_{\rm cms}<3.53$, down to zero transverse
momentum, by reconstructing the $\psi$(2S) decay to a muon pair. The $\psi$(2S)
production cross section $\sigma_{\psi(\rm 2S)}$ is presented as a function of
the collision centrality, which is estimated through the energy deposited in
forward rapidity calorimeters. The relative strength of nuclear effects on the
$\psi$(2S) and on the corresponding 1S charmonium state J/$\psi$ is then
studied by means of the double ratio of cross sections $[\sigma_{\psi(\rm
2S)}/\sigma_{\rm J/\psi}]_{\rm pPb}/[\sigma_{\psi(\rm 2S)}/\sigma_{\rm
J/\psi}]_{\rm pp}$ between p-Pb and pp collisions, and by the values of the
nuclear modification factors for the two charmonium states. The results show a
large suppression of $\psi$(2S) production relative to the J/$\psi$ at backward
(negative) rapidity, corresponding to the flight direction of the Pb-nucleus,
while at forward (positive) rapidity the suppressions of the two states are
comparable. Finally, comparisons to results from lower energy experiments and
to available theoretical models are presented.


title: The adjustable thermal resistor by reversibly folding a graphene sheet

abstract:
  Phononic (thermal) devices are studied such as thermal diode, thermal
transistors, thermal logic gates, and thermal memories. However, the thermal
resistor has not been demonstrated yet. Here, we propose an instantaneously
adjustable thermal resistor by folded graphene. Through theoretical analysis
and molecular dynamics simulations, we studied the phonon folding effect and
the dependent of thermal resistivity on the length between two folds and the
overall length. Further, we discuss on the possibility to realize the
instantaneously adjustable thermal resistor in experiment. Our studies bring
insights in designing thermal resistor and understanding thermal modulation of
2D materials by adjusting its basic structure parameters.


title:
Tracing black hole accretion with SED decomposition and IR lines: from
  local galaxies to the high-z Universe

abstract:
  We present new estimates of AGN accretion and star-formation luminosity in
galaxies obtained for the local 12-$\mu$m sample of Seyfert galaxies (12MGS),
by performing a detailed broad-band spectral energy distribution (SED)
decomposition including the emission of stars, dust heated by star formation
and a possible AGN dusty torus. Thanks to the availability of data from the
X-rays to the sub-millimetre, we constrain and test the contribution of the
stellar, AGN and star-formation components to the SEDs. The availability of
Spitzer-IRS low resolution mid-infrared (mid-IR) spectra is crucial to
constrain the dusty torus component at its peak wavelengths. The results of
SED-fitting are also tested against the available information in other bands:
the reconstructed AGN bolometric luminosity is compared to those derived from
X-rays and from the high excitation IR lines tracing AGN activity like [Ne V]
and [O IV]. The IR luminosity due to star-formation (SF) and the intrinsic AGN
bolometric luminosity are shown to be strongly related to the IR line
luminosity. Variations of these relations with different AGN fractions are
investigated, showing that the relation dispersions are mainly due to different
AGN relative contribution within the galaxy. Extrapolating these local
relations between line and SF or AGN luminosities to higher redshifts, by means
of recent Herschel galaxy evolution results, we then obtain mid- and far-IR
line luminosity functions useful to estimate how many star-forming galaxies and
AGN we expect to detect in the different lines at different redshifts and
luminosities with future IR facilities (e.g., JWST, SPICA).


title:
RVB States in doped Band Insulators from Coloumb forces: Theory and a
  case study of Superconductivity in BiS$_2$ Layers

abstract:
  Doped band insulators, HfNCl, WO$_3$, diamond, Bi$_2$Se$_3$, \bis2 families,
STO/LAO interface, gate doped SrTiO$_3$ and MoS$_2$ etc. are unusual
superconductors. With an aim to build a general theory for superconductivity in
doped band insulators we focuss on \bis2 family, discovered by Mizuguchi et al.
in 2012. While maximum Tc is only $\sim$ 11 K in \laofx, a number of
experimental results are puzzling and anomalous; they resemble high Tc and
unconventional superconductors. Using a two orbital model of Usui, Suzuki and
Kuroki we show that the uniform low density free fermi sea in \laofh is
\textit{unstable towards formation of next nearest neighbor Bi-S-Bi diagonal
valence bond} (charge -2e Cooper pair) and their \textit{Wigner
crystallization}. Instability to this novel state of matter is caused by
unscreened nearest neighbor coulomb repulsions (V $\sim$ 1 eV) and a hopping
pattern with sulfur mediated diagonal next nearest neighbor Bi-S-Bi hopping t'
$\sim$ 0.88 eV, larger than nearest neighbor Bi-Bi hopping, t $\sim$ 0.16 eV.
Wigner crystal of Cooper pairs quantum melt for doping around x = 0.5 and
stabilize certain resonating valence bond states and superconductivity. We
study few variational RVB states and suggest that \bis2 family members are
latent high Tc superconductors, but challenged by competing orders and fragile
nature of manybody states sustained by unscreened Coulomb forces. One of our
superconducting state has d$_{xy}$ symmetry and a gap. We also predict 2d
\textit{Bose metal or vortex liquid} normal state, as charge -2e valence bonds
survive in the normal state.


title: Null curve evolution in four-dimensional pseudo-Euclidean spaces

abstract:
  We define a Lie bracket on a certain set of local vector fields along a null
curve in a 4-dimensional semi-Riemannian space form. This Lie bracket will be
employed to study integrability properties of evolution equations for null
curves in a pseudo-Euclidean space. In particular, a geometric recursion
operator generating infinite many local symmetries for the null localized
induction equation is provided.


title: Weyl semi-metals : a short review

abstract:
  We begin this review with an introduction and a discussion of Weyl fermions
as emergent particles in condensed matter systems, and explain how high energy
phenomena like the chiral anomaly can be seen in low energy experiments. We
then explain the current interest in the field due to the recent discovery of
real materials which behave like Weyl semi-metals. We then describe a simple
lattice model of a topological insulator, which can be turned into a Weyl
semi-metal on breaking either time-reversal or inversion symmetry, and show how
flat bands or Fermi arcs develop. Finally, we describe some new phenomena which
occur due to the chiral nature of the Weyl nodes and end with possible future
prospects in the field, both in theory and experiment.


title:
Gamma-convergence and relaxations for gradient flows in metric spaces: a
  minimizing movement approach

abstract:
  We present new abstract results on the interrelation between the minimizing
movement scheme for gradient flows along a sequence of Gamma-converging
functionals and the gradient flow motion for the corresponding limit
functional, in a general metric space. We are able to allow a relaxed form of
minimization in each step of the scheme, and so we present new relaxation
results too.


title:
$L^2$ Solvability of boundary value problems for divergence form
  parabolic equations with complex coefficients

abstract:
  We consider parabolic operators of the form $$\partial_t+\mathcal{L},\
\mathcal{L}=-\mbox{div}\, A(X,t)\nabla,$$ in $\mathbb
R_+^{n+2}:=\{(X,t)=(x,x_{n+1},t)\in \mathbb R^{n}\times \mathbb R\times \mathbb
R:\ x_{n+1}>0\}$, $n\geq 1$. We assume that $A$ is a $(n+1)\times
(n+1)$-dimensional matrix which is bounded, measurable, uniformly elliptic and
complex, and we assume, in addition, that the entries of A are independent of
the spatial coordinate $x_{n+1}$ as well as of the time coordinate $t$. For
such operators we prove that the boundedness and invertibility of the
corresponding layer potential operators are stable on $L^2(\mathbb
R^{n+1},\mathbb C)=L^2(\partial\mathbb R^{n+2}_+,\mathbb C)$ under complex,
$L^\infty$ perturbations of the coefficient matrix. Subsequently, using this
general result, we establish solvability of the Dirichlet, Neumann and
Regularity problems for $\partial_t+\mathcal{L}$, by way of layer potentials
and with data in $L^2$, assuming that the coefficient matrix is a small complex
perturbation of either a constant matrix or of a real and symmetric matrix.


title: Evolution of perpendicular magnetized tunnel junctions upon annealing

abstract:
  We study the evolution of perpendicularly magnetized tunnel junctions under
300 to 400 $^{\circ}$C annealing. The hysteresis loops do not evolve much
during annealing and they are not informative of the underlying structural
evolutions. These evolutions are better revealed by the frequencies of the
ferromagnetic resonance eigenmodes of the tunnel junction. Their modeling
provides the exchange couplings and the layers' anisotropies within the stack
which can serve as a diagnosis of the tunnel junction state after each
annealing step. The anisotropies of the two CoFeB-based parts and the two
Co/Pt-based parts of the tunnel junction decay at different rates during
annealing. The ferromagnet exchange coupling through the texture-breaking Ta
layer fails above 375$^{\circ}$C. The Ru spacer meant to promote a synthetic
antiferromagnet behavior is also insufficiently robust to annealing. Based on
these evolutions we propose optimization routes for the next generation tunnel
junctions.


title: An improved exact inversion formula for cone beam vector tomography

abstract:
  In this article we present an improved exact inversion formula for the 3D
cone beam transform of vector fields. It is well known that only the solenoidal
part of a vector field can be determined by the longitudinal ray transform of a
vector field in cone beam geometry. The exact inversion formula, as it was
developed in A. Katsevich and T. Schuster, 'An exact inversion formula for cone
beam vector tomography', Inverse Problems 29 (2013), consists of two parts. the
first part is of filtered backprojection type, whereas the second part is a
costly 4D integration and very inefficient. In this article we tackle this
second term and achieve an improvement which is easily to implement and saves
one order of integration. The theory says that the first part contains all
information about the curl of the field, whereas the second part presumably has
information about the boundary values. This suggestion is supported by the fact
that the second part vanishes if the exact field is divergence free and
tangential at the boundary. A number of numerical tests, that are also subject
of this article, confirm the theoretical results and the exactness of the
formula.


title: Still Wrong Use of Pairings in Cryptography

abstract:
  Several pairing-based cryptographic protocols are recently proposed with a
wide variety of new novel applications including the ones in emerging
technologies like cloud computing, internet of things (IoT), e-health systems
and wearable technologies. There have been however a wide range of incorrect
use of these primitives. The paper of Galbraith, Paterson, and Smart (2006)
pointed out most of the issues related to the incorrect use of pairing-based
cryptography. However, we noticed that some recently proposed applications
still do not use these primitives correctly. This leads to unrealizable,
insecure or too inefficient designs of pairing-based protocols. We observed
that one reason is not being aware of the recent advancements on solving the
discrete logarithm problems in some groups. The main purpose of this article is
to give an understandable, informative, and the most up-to-date criteria for
the correct use of pairing-based cryptography. We thereby deliberately avoid
most of the technical details and rather give special emphasis on the
importance of the correct use of bilinear maps by realizing secure
cryptographic protocols. We list a collection of some recent papers having
wrong security assumptions or realizability/efficiency issues. Finally, we give
a compact and an up-to-date recipe of the correct use of pairings.


title:
Multiple stellar populations in the globular cluster M3 (NGC 5272): a
  Str\"omgren perspective

abstract:
  We present Str\"omgren photometry of the Galactic Globular Cluster M3 to
study its multiple generations phenomenon. The use of different
colour-magnitude diagrams and especially of the notoriously efficient c_y index
allowed us to detect a double Red Giant Branch in the cluster CMD. After
decontamination from fore- and background sources, the two sequences turned out
to be equally populated. The two components also show a bimodal radial
distribution well corresponding to that predicted by numerical simulations for
clusters living in an intermediate dynamical evolutive state and with a
population with modified chemical composition that was born more centrally
concentrated than the primordial. The analysis of high-resolution spectra
quantitatively demonstrates that the two detected sequences correspond to the
first (Na-poor) generation and the second (Na-rich) generation, thus confirming
the importance of synergy between photometry and spectroscopy.


title: Gaussian entanglement in the turbulent atmosphere

abstract:
  We provide a rigorous treatment of the entanglement properties of two-mode
Gaussian states in atmospheric channels by deriving and analyzing the
input-output relations for the corresponding entanglement test. A key feature
of such turbulent channels is a non-trivial dependence of the transmitted
continuous-variable entanglement on coherent displacements of the quantum state
of the input field. Remarkably, this allows one to optimize the entanglement
certification by modifying local coherent amplitudes using a finite, but
optimal amount of squeezing. In addition, we propose a protocol which, in
principle, renders it possible to transfer the Gaussian entanglement through
any turbulent channel over arbitrary distances. Therefore, our approach
provides the theoretical foundation for advanced applications of Gaussian
entanglement in free-space quantum communication.


title:
Electric dipole spin resonance in systems with a valley dependent
  g-factor

abstract:
  In this theoretical study we qualitatively and quantitatively investigate the
electric dipole spin resonance (EDSR) in a single Si/SiGe quantum dot in the
presence of a magnetic field gradient, e.g., produced by a ferromagnet. We
model a situation in which the control of electron spin states is achieved by
applying an oscillatory electric field, inducing real-space oscillations of the
electron inside the quantum dot. One of the goals of our study is to present a
microscopic theory of valley dependent $g$-factors in Si/SiGe quantum dots and
investigate how valley relaxation combined with a valley dependent $g$-factor
leads to a novel electron spin dephasing mechanism. Furthermore, we discuss the
interplay of spin and valley relaxations in Si/SiGe quantum dots. Our findings
suggest that the electron spin dephases due to valley relaxation, and are in
agreement with recent experimental studies [Nature Nanotechnology 9, 666-670
(2014)].


title: Tunable magnetic alignment between trapped exciton-polariton condensates

abstract:
  Tunable spin correlations are found to arise between two neighboring trapped
exciton-polariton condensates which spin-polarize spontaneously. We observe a
crossover from an antiferromagnetic- to a ferromagnetic pair state by reducing
the coupling barrier in real-time using control of the imprinted pattern of
pump light. Fast optical switching of both condensates is then achieved by
resonantly but weakly triggering only a single condensate. These effects can be
explained as the competition between spin bifurcations and spin-preserving
Josephson coupling between the two condensates, and open the way to polariton
Bose-Hubbard ladders.


title: Oxygen vacancies: The origin of n-type conductivity in ZnO

abstract:
  Oxygen vacancy (VO) is a common native point defects that plays crucial roles
in determining the physical and chemical properties of metal oxides such as
ZnO. However, fundamental understanding of VO is still very sparse.
Specifically, whether VO is mainly responsible for the n-type conductivity in
ZnO has been still unsettled in the past fifty years. Here we report on a study
of oxygen self-diffusion by conceiving and growing oxygen-isotope ZnO
heterostructures with delicately-controlled chemical potential and Fermi level.
The diffusion process is found to be predominantly mediated by VO. We further
demonstrate that, in contrast to the general belief of their neutral attribute,
the oxygen vacancies in ZnO are actually +2 charged and thus responsible for
the unintentional n-type conductivity as well as the non-stoichiometry of ZnO.
The methodology can be extended to study oxygen-related point defects and their
energetics in other technologically important oxide materials.


title: Hadron production within PHSD

abstract:
  We study the production of hadrons in nucleus-nucleus collisions within the
Parton-Hadron-String Dynamics (PHSD) transport approach that is extended to
incorporate essentials aspects of chiral symmetry restoration (CSR) in the
hadronic sector (via the Schwinger mechanism) on top of the deconfinement phase
transition as implemented in PHSD. The essential impact of CSR is found in the
Schwinger mechanism (for string decay) which fixes the ratio of strange to
light quark production in the hadronic medium. Our studies provide a
microscopic explanation for the maximum in the $K^+/\pi^+$ ratio at about 30 A
GeV which only shows up if in addition to CSR a deconfinement transition to
partonic degrees-of-freedom is incorporated in the reaction dynamics.


title:
Eigenstate Thermalization Hypothesis and Quantum Jarzynski Relation for
  Pure Initial States

abstract:
  Since the first suggestion of the Jarzynski equality many derivations of this
equality have been presented in both, the classical and the quantum context.
While the approaches and settings greatly differ from one to another, they all
appear to rely on the initial state being a thermal Gibbs state. Here, we
present an investigation of work distributions in driven isolated quantum
systems, starting off from pure states that are close to energy eigenstates of
the initial Hamiltonian. We find that, for the nonintegrable system in quest,
the Jarzynski equality is fulfilled to good accuracy.

categories: quant-ph cond-mat.stat-mech cond-mat.str-el physics.comp-ph


title:
Inference and rare event simulation for stopped Markov processes via
  reverse-time sequential Monte Carlo

abstract:
  We present a sequential Monte Carlo algorithm for Markov chain trajectories
with proposals constructed in reverse time, which is advantageous when paths
are conditioned to end in a rare set. The reverse time proposal distribution is
constructed by approximating the ratio of Green's functions in Nagasawa's
formula. Conditioning arguments can be used to interpret these ratios as
low-dimensional conditional sampling distributions of some coordinates of the
process given the others. Hence the difficulty in designing SMC proposals in
high dimension is greatly reduced. We illustrate our method on estimating an
overflow probability in a queueing model, the probability that a diffusion
follows a narrowing corridor, and the initial location of an infection in an
epidemic model on a network.


title: Unexpected red shift of C-H vibrational band of Methyl benzoate

abstract:
  The C-H vibrational bands become more and more important in the structural
determination of biological molecules with the development of CARS microscopy
and 2DIR spectroscopy. Due to the congested pattern, near degeneracy, and
strong anharmonicity of the C-H stretch vibrations, assignment of the C-H
vibrational bands are often misleading. Anharmonic vibrational spectra
calculation with multidimensional potential energy surface interprets the C-H
vibrational spectra more accurately. In this article we have presented the
importance of multidimensional potential energy surface in anharmonic
vibrational spectra calculation and discuss the unexpected red shift of C-H
vibrational band of Methyl benzoate.


title:
Faster learning of deep stacked autoencoders on multi-core systems using
  synchronized layer-wise pre-training

abstract:
  Deep neural networks are capable of modelling highly non-linear functions by
capturing different levels of abstraction of data hierarchically. While
training deep networks, first the system is initialized near a good optimum by
greedy layer-wise unsupervised pre-training. However, with burgeoning data and
increasing dimensions of the architecture, the time complexity of this approach
becomes enormous. Also, greedy pre-training of the layers often turns
detrimental by over-training a layer causing it to lose harmony with the rest
of the network. In this paper a synchronized parallel algorithm for
pre-training deep networks on multi-core machines has been proposed. Different
layers are trained by parallel threads running on different cores with regular
synchronization. Thus the pre-training process becomes faster and chances of
over-training are reduced. This is experimentally validated using a stacked
autoencoder for dimensionality reduction of MNIST handwritten digit database.
The proposed algorithm achieved 26\% speed-up compared to greedy layer-wise
pre-training for achieving the same reconstruction accuracy substantiating its
potential as an alternative.


title: Behavior of Friedmann-Lemaitre-Robertson-Walker Singularities

abstract:
  A regularization procedure has been recently suggested for regularizing Big
Bang singularities in Friedmann-Lemaitre-Robertson-Walker (FLRW) spacetimes. We
argue that this procedure is only appliable to one case of Big Bang
singularities and does not affect other types of singularities.


title:
Axially symmetric equations for differential pulsar rotation with
  superfluid entrainment

abstract:
  In this article we present an analytical two-component model for pulsar
rotational dynamics. Under the assumption of axial symmetry, implemented by a
paraxial array of straight vortices that thread the entire neutron superfluid,
we are able to project exactly the 3D hydrodynamical problem to a 1D
cylindrical one. In the presence of density dependent entrainment the
superfluid rotation is non-columnar: we circumvent this by using an auxiliary
dynamical variable directly related to the areal density of vortices. The main
result is a system of differential equations that take consistently into
account the stratified spherical structure of the star, the dynamical effects
of non-uniform entrainment, the differential rotation of the superfluid
component and its coupling to the normal crust. These equations represent a
mathematical framework in which to test quantitatively the macroscopic
consequences of the presence of a stable vortex array, a working hypothesis
widely used in glitch models. Even without solving the equations explicitly, we
are able to draw some general quantitative conclusions; in particular, we show
that the reservoir of angular momentum (corresponding to recent values of the
pinning forces) is enough to reproduce the largest glitch observed in the Vela
pulsar, provided its mass is not too large.


title: Starting Small -- Learning with Adaptive Sample Sizes

abstract:
  For many machine learning problems, data is abundant and it may be
prohibitive to make multiple passes through the full training set. In this
context, we investigate strategies for dynamically increasing the effective
sample size, when using iterative methods such as stochastic gradient descent.
Our interest is motivated by the rise of variance-reduced methods, which
achieve linear convergence rates that scale favorably for smaller sample sizes.
Exploiting this feature, we show -- theoretically and empirically -- how to
obtain significant speed-ups with a novel algorithm that reaches statistical
accuracy on an $n$-sample in $2n$, instead of $n \log n$ steps.


title:
Tauberian properties for monomial summability with applications to
  Pfaffian systems

abstract:
  In this paper we will show that monomial summability processes with respect
to different monomials are not compatible, except in the (trivial) case of a
convergent series. We will apply this fact to the study of solutions of
Pfaffian systems with normal crossings, focusing in the implications of the
complete integrability condition on these systems.


title: Improper coloring of graphs on surfaces

abstract:
  A graph $G$ is $(d_1,\ldots,d_k)$-colorable if its vertex set can be
partitioned into $k$ sets $V_1,\ldots,V_k$, such that for each $i\in\{1,
\ldots, k\}$, the subgraph of $G$ induced by $V_i$ has maximum degree at most
$d_i$. The Four Color Theorem states that every planar graph is
$(0,0,0,0)$-colorable, and a classical result of Cowen, Cowen, and Woodall
shows that every planar graph is $(2,2,2)$-colorable. In this paper, we extend
both of these results to graphs on surfaces. Namely, we show that every graph
embeddable on a surface of Euler genus $g>0$ is $(0,0,0,9g-4)$-colorable and
$(2,2,9g-4)$-colorable. Moreover, these graphs are also
$(0,0,O(\sqrt{g}),O(\sqrt{g}))$-colorable and
$(2,O(\sqrt{g}),O(\sqrt{g}))$-colorable. We also prove that every triangle-free
graph that is embeddable on a surface of Euler genus $g$ is $(0, 0,
O(g))$-colorable. This is an extension of Gr\"{o}tzsch's Theorem, which states
that triangle-free planar graphs are $(0, 0, 0)$-colorable. Finally, we prove
that every graph of girth at least 7 that is embeddable on a surface of Euler
genus $g$ is $(0,O(\sqrt{g}))$-colorable. All these results are best possible
in several ways as the girth condition is sharp, the constant maximum degrees
cannot be improved, and the bounds on the maximum degrees depending on $g$ are
tight up to a constant multiplicative factor.


title:
Equilibration of isolated many-body quantum systems with respect to
  general distinguishability measures

abstract:
  We demonstrate equilibration of isolated many-body systems in the sense that,
after initial transients have died out, the system behaves practically
indistinguishable from a time-independent steady state, i.e., non-negligible
deviations are unimaginably rare in time. Measuring the distinguishability in
terms of quantum mechanical expectation values, results of this type have been
previously established under increasingly weak assumptions about the initial
disequilibrium, the many-body Hamiltonian, and the considered observables.
Here, we further extend these results with respect to generalized
distinguishability measures which fully take into account the fact that the
actually observed, primary data are not expectation values but rather the
probabilistic occurrence of different possible measurement outcomes.


title: Existence of minimizers for the $2$d stationary Griffith fracture model

abstract:
  We consider the variational formulation of the Griffith fracture model in two
spatial dimensions and prove existence of strong minimizers, that is
deformation fields which are continuously differentiable outside a closed jump
set and which minimize the relevant energy. To this aim, we show that
minimizers of the weak formulation of the problem, set in the function space
$SBD^2$ and for which existence is well-known, are actually strong minimizers
following the approach developed by De Giorgi, Carriero, and Leaci in the
corresponding scalar setting of the Mumford-Shah problem.


title: Fast Training of Triplet-based Deep Binary Embedding Networks

abstract:
  In this paper, we aim to learn a mapping (or embedding) from images to a
compact binary space in which Hamming distances correspond to a ranking measure
for the image retrieval task.
  We make use of a triplet loss because this has been shown to be most
effective for ranking problems.
  However, training in previous works can be prohibitively expensive due to the
fact that optimization is directly performed on the triplet space, where the
number of possible triplets for training is cubic in the number of training
examples.
  To address this issue, we propose to formulate high-order binary codes
learning as a multi-label classification problem by explicitly separating
learning into two interleaved stages.
  To solve the first stage, we design a large-scale high-order binary codes
inference algorithm to reduce the high-order objective to a standard binary
quadratic problem such that graph cuts can be used to efficiently infer the
binary code which serve as the label of each training datum.
  In the second stage we propose to map the original image to compact binary
codes via carefully designed deep convolutional neural networks (CNNs) and the
hashing function fitting can be solved by training binary CNN classifiers.
  An incremental/interleaved optimization strategy is proffered to ensure that
these two steps are interactive with each other during training for better
accuracy.
  We conduct experiments on several benchmark datasets, which demonstrate both
improved training time (by as much as two orders of magnitude) as well as
producing state-of-the-art hashing for various retrieval tasks.


title:
Unsupervised word segmentation and lexicon discovery using acoustic word
  embeddings

abstract:
  In settings where only unlabelled speech data is available, speech technology
needs to be developed without transcriptions, pronunciation dictionaries, or
language modelling text. A similar problem is faced when modelling infant
language acquisition. In these cases, categorical linguistic structure needs to
be discovered directly from speech audio. We present a novel unsupervised
Bayesian model that segments unlabelled speech and clusters the segments into
hypothesized word groupings. The result is a complete unsupervised tokenization
of the input speech in terms of discovered word types. In our approach, a
potential word segment (of arbitrary length) is embedded in a fixed-dimensional
acoustic vector space. The model, implemented as a Gibbs sampler, then builds a
whole-word acoustic model in this space while jointly performing segmentation.
We report word error rates in a small-vocabulary connected digit recognition
task by mapping the unsupervised decoded output to ground truth transcriptions.
The model achieves around 20% error rate, outperforming a previous HMM-based
system by about 10% absolute. Moreover, in contrast to the baseline, our model
does not require a pre-specified vocabulary size.


title:
Stabiliser of an Attractive Fixed Point of an IWIP Automorphism of a
  free product

abstract:
  For a group $G$ of finite Kurosh rank and for some arbiratily free product
decomposition of $G$, $G = H_1 \ast H_2 \ast ... \ast H_r \ast F_q$, where
$F_q$ is a finitely generated free group, we can associate some (relative)
outer space $\mathcal{O}(G, \{H_1,..., H_r \})$. We define the relative
boundary $\partial (G, \{ H_1, ..., H_r \}) = \partial(G, \mathcal{O}) $
corresponding to the free product decomposition, as the set of infinite reduced
words (with respect to free product length). By denoting $Out(G, \{ H_1, ...,
H_r \})$ the subgroup of $Out(G)$ which is consisted of the outer automorphisms
which preserve the set of conjugacy classes of $H_i$'s, we prove that for the
stabiliser $Stab(X)$ of an attractive fixed point in $X \in \partial (G, \{
H_1, ..., H_r \})$ of an irreducible with irreducible powers automorphism
relative to $\mathcal{O}$, it holds that it has a (normal) subgroup $B$
isomorphic to subgroup of $\bigoplus \limits_{i=1} ^{r} Out(H_i)$ such that
$Stab(X) / B$ is isomorphic to $\mathbb{Z}$. The proof relies heavily on the
machinery of the attractive lamination of an IWIP automorphism relative to
$\mathcal{O}$.


title:
Doppler-free approach to optical pumping dynamics in the $6S_{1/2}-
  5D_{5/2}$ electric quadrupole transition of Cesium vapor

abstract:
  The $6S_{1/2}-5D_{5/2}$ electric quadrupole transition is investigated in
Cesium vapor at room temperature via nonlinear Doppler-free 6P-6S-5D
three-level spectroscopy. Frequency-resolved studies of individual E2 hyperfine
lines allow one to analyze optical pumping dynamics, polarization selection
rules and line intensities. It opens the way to studies of transfer of light
orbital angular momentum to atoms, and the influence of metamaterials on E2
line spectra.


title:
Electromagnetic counterparts to gravitational waves from black hole
  mergers and naked singularities

abstract:
  We consider the question here whether the proposed electromagnetic
counterpart of the gravitational wave signals in binary black hole coalescence
may be due to the appearance of a `short lived' naked singularity during the
merger. We point out that the change in topology that the spacetime undergoes
during the merger can cause the appearance of a naked singularity. In case some
matter, in the form of a small accretion disk, is present in the surroundings
of the black hole system then the emitted luminosity during the merger would
allow to distinguish the scenario where the naked singularity forms from the
scenario where the horizon exists at all times. In fact the emitted luminosity
spectrum would be much higher in the case where a naked singularity forms as
opposed to the `pure' black hole case. We suggest that the presence of such a
transient naked singularity will explain the high luminosity of an
electromagnetic counterpart during the merger much more easily.


title: Toward an asymptotic behaviour of the ABC dynamo

abstract:
  The ABC flow was originally introduced by Arnol'd to investigate Lagrangian
chaos. It soon became the prototype example to illustrate magnetic-field
amplification via fast dynamo action, i.e. dynamo action exhibiting
magnetic-field amplification on a typical timescale independent of the
electrical resistivity of the medium. Even though this flow is the most
classical example for this important class of dynamos (with application to
large-scale astrophysical objects), it was recently pointed out (Bouya Isma\"el
and Dormy Emmanuel, Phys. Fluids, 25 (2013) 037103) that the fast dynamo nature
of this flow was unclear, as the growth rate still depended on the magnetic
Reynolds number at the largest values available so far $(\text{Rm} = 25000)$ .
Using state-of-the-art high-performance computing, we present high-resolution
simulations (up to 40963) and extend the value of $\text{Rm}$ up to $
5\cdot10^5$ . Interestingly, even at these huge values, the growth rate of the
leading eigenmode still depends on the controlling parameter and an asymptotic
regime is not reached yet. We show that the maximum growth rate is a decreasing
function of $\text{Rm}$ for the largest values of $\text{Rm}$ we could achieve
(as anticipated in the above-mentioned paper). Slowly damped oscillations might
indicate either a new mode crossing or that the system is approaching the limit
of an essential spectrum.


title:
Quantization of Hall Resistance at the Metallic Interface between an
  Oxide Insulator and SrTiO$_{3}$

abstract:
  The two-dimensional metal forming at the interface between an oxide insulator
and SrTiO3 provides new opportunities for oxide electronics. However, the
quantum Hall effect, one of the most fascinating effects of electrons confined
in two dimensions, remains underexplored at these complex oxide
heterointerfaces. Here, we report the experimental observation of quantized
Hall resistance in a SrTiO3 heterointerface based on the modulation-doped
amorphous-LaAlO$_{3}$/SrTiO$_{3}$ heterostructure, which exhibits both high
electron mobility exceeding 10000 cm$^{2}$/Vs and low carrier density on the
order of ~10$^{12}$ cm$^{-2}$. Along with unambiguous Shubnikov-de Haas
oscillations, the spacing of the quantized Hall resistance suggests that the
interface is comprised of a single quantum well with ten parallel conducting
two-dimensional subbands. This provides new insight into the electronic
structure of conducting oxide interfaces and represents an important step
towards designing and understanding advanced oxide devices.


title: On stability of the Kasner solution in quadratic gravity

abstract:
  We consider dynamics of a flat anisotropic Universe filled by a perfect fluid
near a cosmological singularity in quadratic gravity. Two possible regimes are
described -- the Kasner anisotropic solution and an isotropic "vacuum
radiation" solution which has three sub cases depending on whether the equation
of state parameter $w$ is bigger, smaller or equals to $1/3$. Initial
conditions for numerical integrations have been chosen near General Relativity
anisotropic solution with matter (Jacobs solution). We have found that for such
initial conditions there is a range of values of coupling constants so that the
resulting cosmological singularity is isotropic.


title:
Primordial Magnetic Field Via Weibel Instability In The Quark Gluon
  Plasma Phase

abstract:
  The origin of the observed large scale magnetic fields in the Universe is a
mystery. The seed of these magnetic fields has been attributed to physical
process in the early universe. In this work we provide a mechanism for the
generation of a primordial magnetic field in the early universe via the Weibel
instability in the quark gluon plasma. The Weibel instability occurs in the
plasma if there is an anisotropy in the particle distribution function of the
particles. In early universe, the velocity anisotropy required for Weibel
instability to operate is generated in the quark gluon plasma by the collapse
of closed $Z(3)$ domain walls that arise in the deconfined phase of the QCD
(above $T\sim 200$ MeV). Such large domains can arise in the context of certain
low energy scale inflationary models. The closed domains undergo supersonic
collapse and the velocity anisotropy is generated in the shocks produced in the
wake of the collapsing domain walls. This results in a two stream Weibel
instability in the ultra-relativistic quark gluon plasma. The instability in
turn generates strong magnetic fields in the plasma. We find that the field
strengths generated can be comparable to the equipartition energy density at
the QCD scale which is of the order of $10^{18}$ G.


title:
A Time-Space Trade-off for Computing the k-Visibility Region of a Point
  in a Polygon

abstract:
  Let $P$ be a simple polygon with $n$ vertices, and let $q \in P$ be a point
in $P$. Let $k \in \{0, \dots, n - 1\}$. A point $p \in P$ is $k$-visible from
$q$ if and only if the line segment $pq$ crosses the boundary of $P$ at most
$k$ times. The $k$-visibility region of $q$ in $P$ is the set of all points
that are $k$-visible from $q$. We study the problem of computing the
$k$-visibility region in the limited workspace model, where the input resides
in a random-access read-only memory of $O(n)$ words, each with
$\Omega(\log{n})$ bits. The algorithm can read and write $O(s)$ additional
words of workspace, where $s \in \mathbb{N}$ is a parameter of the model. The
output is written to a write-only stream.
  Given a simple polygon $P$ with $n$ vertices and a point $q \in P$, we
present an algorithm that reports the $k$-visibility region of $q$ in $P$ in
$O(cn/s+c\log{s} + \min\{\lceil k/s \rceil n,n \log{\log_s{n}}\})$ expected
time using $O(s)$ words of workspace. Here, $c \in \{1, \dots, n\}$ is the
number of critical vertices of $P$ for $q$ where the $k$-visibility region of
$q$ may change. We generalize this result for polygons with holes and for sets
of non-crossing line segments.


abstract:
  Quantum geometrodynamics with intrinsic time development is presented.
Paradigm shift from full space-time covariance to spatial diffeomorphism
invariance yields a non-vanishing Hamiltonian, a resolution of the `problem of
time', and gauge-invariant temporal ordering in an ever expanding universe.
Einstein's general relativity is a particular realization of a wider class of
theories; and the framework prompts natural extensions and improvements, with
the consequent dominance of Cotton-York potential at early times when the
universe was small.


title: Cold CO gas in the disk of the young eruptive star EX Lup

abstract:
  EX Lupi-type objects (EXors) form a sub-class of T Tauri stars, defined by
sudden sporadic flare-ups of 1-5 magnitudes at optical wavelengths. These
eruptions are attributed to enhanced mass accretion from the circumstellar disk
to the star, and may constitute important events in shaping the structure of
the inner disk and the forming planetary system. Although disk properties must
play a fundamental role in driving the outbursts, they are surprisingly poorly
known. In order to characterize the dust and gas components of EXor disks, here
we report on observations of the $^{12}$CO J=3-2 and 4-3 lines, and the
$^{13}$CO 3-2 line in EX Lup, the prototype of the EXor class. We reproduce the
observed line fluxes and profiles with a line radiative transfer model, and
compare the obtained parameters with corresponding ones of other T Tauri disks.


title:
On the joint spectra of the two dimensional Lie algebra of operators in
  Hilbert spaces

abstract:
  We consider the complex solvable non-commutative two dimensional Lie algebra
$L$, $L=<y>\oplus <x>$, with Lie bracket $[x,y]=y$, as linear bounded operators
acting on a complex Hilbert space $H$. Under the assumption $R(y)$ closed, we
reduce the computation of the joint spectra $Sp(L,E)$, $\sigma_{\delta
,k}(L,E)$ and $\sigma_{\pi ,k}(L,E)$, $k= 0,1,2$, to the computation of the
spectrum, the approximate point spectrum, and the approximate compression
spectrum of a single operator. Besides, we also study the case $y^2=0$, and we
apply our results to the case $H$ finite dimensional.


title: 1/n Expansion of Resonant States

abstract:
  We present a general analytic expansion in powers of $1/n$ of the resonant
states of quantum-mechanical systems, where $n=1,2,3,\cdots$ is the excitation
number. Explicit formulas are obtained for some potential barrier models.


title: Semi-orthogonal decompositions of GIT quotient stacks

abstract:
  If G is a reductive group which acts on a linearized smooth scheme $X$ then
we show that under suitable standard conditions the derived category of
coherent sheaves of the corresponding GIT quotient stack $X^{ss}/G$ has a
semi-orthogonal decomposition consisting of derived categories of coherent
sheaves of rings on the categorical quotient $X^{ss}/\!/G$ which are locally of
finite global dimension. One of the components of the decomposition is a
certain non-commutative resolution of $X^{ss}/\!/G$ constructed earlier by the
authors.
  As a concrete example we obtain in the case of odd Pfaffians a
semi-orthogonal decomposition of the corresponding quotient stack in which all
the parts are certain specific non-commutative crepant resolutions of Pfaffians
of lower or equal rank which had also been constructed earlier by the authors.
In particular this semi-orthogonal decomposition cannot be refined further
since its parts are Calabi-Yau.
  The results in this paper also complement a result by Halpern-Leistner (and
similar results by Ballard-Favero-Katzarkov and Donovan-Segal) that asserts the
existence of a semi-orthogonal decomposition of the derived category of $X/G$
in which one of the components is the derived category of $X^{ss}/G$.


title:
Statistical characterization of deviations from planned flight
  trajectories in air traffic management

abstract:
  Understanding the relation between planned and realized flight trajectories
and the determinants of flight deviations is of great importance in air traffic
management. In this paper we perform an in depth investigation of the
statistical properties of planned and realized air traffic on the German
airspace during a 28 day periods, corresponding to an AIRAC cycle. We find that
realized trajectories are on average shorter than planned ones and this effect
is stronger during night-time than daytime. Flights are more frequently
deviated close to the departure airport and at a relatively large angle to
destination. Moreover, the probability of a deviation is higher in low traffic
phases. All these evidences indicate that deviations are mostly used by
controllers to give directs to flights when traffic conditions allow it.
Finally we introduce a new metric, termed difork, which is able to characterize
navigation points according to the likelihood that a deviation occurs there.
Difork allows to identify in a statistically rigorous way navigation point
pairs where deviations are more (less) frequent than expected under a null
hypothesis of randomness that takes into account the heterogeneity of the
navigation points. Such pairs can therefore be seen as sources of flexibility
(stability) of controllers traffic management while conjugating safety and
efficiency.


title: Yang-Mills Instanton Sheaves

abstract:
  The SL(2,C) Yang-Mills instanton solutions constructed recently by the
biquaternion method were shown to satisfy the complex version of the ADHM
equations and the Monad construction. Moreover, we discover that, in addition
to the holomorphic vector bundles on CP^3 similar to the case of SU(2) ADHM
construction, the SL(2,C) instanton solutions can be used to explicitly
construct instanton sheaves on CP^3. Presumably, the existence of these
instanton sheaves is related to the singularities of the SL(2,C) instantons on
S^4 which do not exist for SU(2) instantons.


title:
Masses of the components of SB2 binaries observed with Gaia. III.
  Accurate SB2 orbits for 10 binaries and masses of HIP 87895

abstract:
  In anticipation of the Gaia astrometric mission, a large sample of
spectroscopic binaries has been observed since 2010 with the SOPHIE
spectrograph at the Haute--Provence Observatory. Our aim is to derive the
orbital elements of double-lined spectroscopic binaries (SB2s) with an accuracy
sufficient to finally obtain the masses of the components with relative errors
as small as 1 % when the astrometric measurements of Gaia are taken into
account. In this paper we present the results from five years of observations
of 10 SB2 systems with periods ranging from 37 to 881 days. Using the TODMOR
algorithm we computed radial velocities from the spectra, and then derived the
orbital elements of these binary systems. The minimum masses of the components
are then obtained with an accuracy better than 1.2 % for the ten binaries.
Combining the radial velocities with existing interferometric measurements, we
derived the masses of the primary and secondary components of HIP 87895 with an
accuracy of 0.98 % and 1.2 % respectively.


title:
Is the World Local or Nonlocal? Towards an Emergent Quantum Mechanics in
  the 21st Century

abstract:
  What defines an emergent quantum mechanics (EmQM)? Can new insight be
advanced into the nature of quantum nonlocality by seeking new links between
quantum and emergent phenomena as described by self-organization, complexity,
or emergence theory? Could the development of a future EmQM lead to a unified,
relational image of the cosmos? One key motivation for adopting the concept of
emergence in relation to quantum theory concerns the persistent failure in
standard physics to unify the two pillars in the foundations of physics:
quantum theory and general relativity theory (GRT). The total contradiction in
the foundational, metaphysical assumptions that define orthodox quantum theory
versus GRT might render inter-theoretic unification impossible. On the one
hand, indeterminism and non-causality define orthodox quantum mechanics, and,
on the other hand, GRT is governed by causality and determinism. How could
these two metaphysically-contradictory theories ever be reconciled? The present
work argues that metaphysical contradiction necessarily implies physical
contradiction. The contradictions are essentially responsible also for the
measurement problem in quantum mechanics. A common foundation may be needed for
overcoming the contradictions between the two foundational theories. The
concept of emergence, and the development of an EmQM, might help advance a
common foundation - physical and metaphysical - as required for successful
inter-theory unification.


title: LDA Lattices Without Dithering Achieve Capacity on the Gaussian Channel

abstract:
  This paper deals with Low-Density Construction-A (LDA) lattices, which are
obtained via Construction A from non-binary Low-Density Parity-Check codes.
More precisely, a proof is provided that Voronoi constellations of LDA lattices
achieve the capacity of the AWGN channel under lattice encoding and decoding.
This is obtained after showing the same result for more general Construction-A
lattice constellations. The theoretical analysis is carried out in a way that
allows to describe how the prime number underlying Construction A behaves as a
function of the lattice dimension. Moreover, no dithering is required in the
transmission scheme, simplifying some previous solutions of the problem.
Remarkably, capacity is achievable with LDA lattice codes whose parity-check
matrices have constant row and column Hamming weights. Some expansion
properties of random bipartite graphs constitute an extremely important tool
for dealing with sparse matrices and allow to find a lower bound of the minimum
Euclidean distance of LDA lattices in our ensemble.


title: The autonomous norm on $Ham(\mathbf{R}^{2n})$ is bounded

abstract:
  We prove that the autonomous norm on the group of compactly supported
Hamiltonian diffeomorphisms of the standard $\mathbf{R}^{2n}$ is bounded.


title:
Dyson-Schwinger Approach to Color-Superconductivity: Effects of
  Selfconsistent Gluon Dressing

abstract:
  The phase diagram of dense QCD at nonvanishing temperatures and large quark
chemical potentials is studied with Dyson-Schwinger equations for 2+1 quark
flavors, focusing on color-superconducting phases with 2SC and CFL-like
pairing. The truncation scheme of our previous investigations is extended to
include the dressing of gluons with selfconsistently determined quarks, i.e.,
taking into account the dynamical masses and superconducting gaps of the quarks
in the gluon polarization. As a consequence the gluon screening is reduced,
leading to an enhancement of the critical temperatures of the
color-superconducting phases by about a factor of 2 as compared to the case
where the gluons are dressed with bare quarks. We also calculate the Debye and
Meissner masses of the gluons and show that they are consistent with
weak-coupling results.


title: Black Hole Entropy from Entropy of Hawking Radiation

abstract:
  We provide a simple way for calculating the entropy of a Schwarzschild black
hole from the entropy of its Hawking radiation. To this end, we show that if a
thermodynamic system loses its energy only through the black body radiation,
its loss of entropy is always 3/4 of the entropy of the emitted radiation. This
proposition enables us to relate the entropy of an evaporating black hole to
the entropy of its Hawking radiation. Explicitly, by calculating the entropy of
the Hawking radiation emitted in the full period of evaporation of the black
hole, we find the Bekenstein-Hawking entropy of the initial black hole.


title:
Convex duality in optimal investment and contingent claim valuation in
  illiquid markets

abstract:
  This paper studies convex duality in optimal investment and contingent claim
valuation in markets where traded assets may be subject to nonlinear trading
costs and portfolio constraints. Under fairly general conditions, the dual
expressions decompose into tree terms, corresponding to the agent's risk
preferences, trading costs and portfolio constraints, respectively. The dual
representations are shown to be valid when the market model satisfies an
appropriate generalization of the no-arbitrage condition and the agent's
utility function satisfies an appropriate generalization of asymptotic
elasticity conditions. When applied to classical liquid market models or models
with bid-ask spreads, we recover well-known pricing formulas in terms of
martingale measures and consistent price systems. Building on the general
theory of convex stochastic optimization, we also derive optimality conditions
in terms of an extended notion of a "shadow price".


title:
Practical Limits in the Sensitivity-Linearity Trade-off for Radio
  Telescope Front Ends in the HF and VHF-low Bands

abstract:
  Radio telescope front ends must have simultaneously low noise and
sufficiently-high linearity to accommodate interfering signals. Typically these
are opposing design goals. For modern radio telescopes operating in the HF
(3-30 MHz) and VHF-low (30-88 MHz) bands, the problem is more nuanced in that
front end noise temperature may be a relatively small component of the system
temperature, and increased linearity may be required due to the particular
interference problems associated with this spectrum. In this paper we present
an analysis of the sensitivity-linearity trade off at these frequencies,
applicable to existing commercially-available monolithic microwave integrated
circuit (MMIC) amplifiers in single-ended, differential, and parallelized
configurations. This analysis and associated findings should be useful in the
design and upgrade of front ends for low frequency radio telescopes. The
analysis is demonstrated explicitly for one of the better-performing amplifiers
encountered in this study, the Mini-Circuits PGA-103, and is confirmed by
hardware measurements. We also present a design based on the Mini-Circuits
HELA-10 amplifier, which is better-suited for applications where linearity is a
primary concern.


title: A Low Cost Eeg Based Bci Prosthetic Using Motor Imagery

abstract:
  Brain Computer Interfaces (BCI) provide the opportunity to control external
devices using the brain ElectroEncephaloGram (EEG) signals. In this paper we
propose two software framework in order to control a 5 degree of freedom
robotic and prosthetic hand. Results are presented where an Emotiv Cognitive
Suite (i.e. the 1st framework) combined with an embedded software system (i.e.
an open source Arduino board) is able to control the hand through character
input associated with the taught actions of the suite. This system provides
evidence of the feasibility of brain signals being a viable approach to
controlling the chosen prosthetic. Results are then presented in the second
framework. This latter one allowed for the training and classification of EEG
signals for motor imagery tasks. When analysing the system, clear visual
representations of the performance and accuracy are presented in the results
using a confusion matrix, accuracy measurement and a feedback bar signifying
signal strength. Experiments with various acquisition datasets were carried out
and with a critical evaluation of the results given. Finally depending on the
classification of the brain signal a Python script outputs the driving command
to the Arduino to control the prosthetic. The proposed architecture performs
overall good results for the design and implementation of economically
convenient BCI and prosthesis.


title: Observation of the $\Lambda_b^0\to\Lambda\phi$ decay

abstract:
  The $\Lambda_b^0\to\Lambda\phi$ decay is observed using data corresponding to
an integrated luminosity of 3.0fb$^{-1}$ recorded by the LHCb experiment. The
decay proceeds at leading order via a $b\to s\bar{s}s$ loop transition and is
therefore sensitive to the possible presence of particles beyond the Standard
Model. A first observation is reported with a significance of $5.9$ standard
deviations. The value of the branching fraction is measured to be
$(5.18\pm1.04\pm0.35\,^{+0.67}_{-0.62})\times10^{-6}$, where the first
uncertainty is statistical, the second is systematic, and the third is related
to external inputs. Triple-product asymmetries are measured to be consistent
with zero.


title:
Uniqueness of infinite open cluster in bond percolation in
  $\mathbb{Z}^d$

abstract:
  In this paper, we alternately obtain the almost sure uniqueness of the
infinite open cluster in bond percolation in $\mathbb{Z}^d, d \geq 2,$ without
requiring the use of ergodicity of translation action. If $N$ denotes the
number of infinite open clusters, we use the Burton-Keane argument to get $N
\in \{0,1,2\}$ a.s. and then use a pivotal edges argument to obtain that $N \in
\{0,1\}$ a.s.


title:
When opposites repel: from metastability to extended chiral spin
  textures in spin ice with short-range topological-defect interactions

abstract:
  We study the interplay of topological bottlenecks and energetic barriers to
equilibration in a Coulomb spin liquid where a short-range energetic coupling
between defects charged under an emergent gauge field supplements their
entropic long-range Coulomb interaction. This work is motivated by the
prevalence of memory effects observed across a wide range of geometrically
frustrated magnetic materials, possibly including the spontaneous Hall effect
observed in Pr2Ir2O7. Our model is canonical spin-ice model on the pyrochlore
lattice, where farther-neighbour spin couplings give rise to a nearest-neighbor
interaction between topological defects which can easily be chosen to be
unnatural or not, i.e. attractive or repulsive between defects of equal gauge
charge. Among the novel features of this model are the following. After
applying a field quench, a rich dynamical approach to equilibrium emerges,
dominated by multi-scale energy barriers responsible for long-lived
magnetization plateaux. These even allow for the metastability of a
"fragmented" spin liquid, an elusive regime where partial order co-exists with
a spin liquid. Perhaps most strikingly, the attraction produces clusters of
defects whose stability is due to a combination of energetic barriers for their
break-up and proximity of opposite charges along with an entropic barrier
generated by the topological requirement of annihilating a defect only together
with an oppositely charged counterpart. These clusters may take the form of a
"jellyfish" spin texture, comprising an arrangement of same-sign gauge-charges,
centered on a hexagonal ring with branches of arbitrary length. The ring
carries a clockwise or counterclockwise circular flow of magnetisation. This
emergent toroidal degrees of freedom provides a possibility for time reversal
symmetry breaking with possible relevance to the spontaneous Hall effect
observed in Pr2Ir2O7.


title: Predicting the optimized thermoelectric performance of MgAgSb

abstract:
  Using first-principles method and Boltzmann theory, we provide an accurate
prediction of the electronic band structure and thermoelectric transport
properties of alpha-MgAgSb. Our calculations demonstrate that only when an
appropriate exchange-correlation functional is chosen can we correctly
reproduce the semiconducting nature of this compound. By fine tuning the
carrier concentration, the thermoelectric performance of alpha-MgAgSb can be
significantly optimized, which exhibits a strong temperature dependence and
gives a maximum ZT value of 1.7 at 550 K.


title:
Libor at crossroads: stochastic switching detection using information
  theory quantifiers

abstract:
  This paper studies the 28 time series of Libor rates, classified in seven
maturities and four currencies), during the last 14 years. The analysis was
performed using a novel technique in financial economics: the
Complexity-Entropy Causality Plane. This planar representation allows the
discrimination of different stochastic and chaotic regimes. Using a temporal
analysis based on moving windows, this paper unveals an abnormal movement of
Libor time series arround the period of the 2007 financial crisis. This
alteration in the stochastic dynamics of Libor is contemporary of what press
called "Libor scandal", i.e. the manipulation of interest rates carried out by
several prime banks. We argue that our methodology is suitable as a market
watch mechanism, as it makes visible the temporal redution in informational
efficiency of the market.


title: Asymptotic behaviour of the Riemann mapping function at analytic cusps

abstract:
  We completely describe the asymptotic behaviour of the Riemann mapping
function and its derivatives at an analytic cusp. We achieve the same for the
inverse of the mapping function.


title: Blackbody Radiation from Isolated Neptunes

abstract:
  Recent analyses of the orbits of some Kuiper Belt objects hypothesize the
presence of an undiscovered Neptune-size planet at a very large separation from
the Sun. The energy budget of Neptunes on such distant orbits is dominated by
the internal heat released by their cooling rather than solar irradiation
(making them effectively "isolated"). The blackbody radiation that these
planets emit as they cool may provide the means for their detection. Here we
use an analytical toy model to study the cooling and radiation of isolated
Neptunes. This model can translate a detection (or a null detection) to a
constraint on the size and composition of the hypothesized "Planet Nine".
Specifically, the thick gas atmosphere of Neptune-like planets serves as an
insulating blanket which slows down their cooling. Therefore, a measurement of
the blackbody temperature, $T_{\rm eff}\sim 50\textrm{K}$, at which a Neptune
emits can be used to estimate the mass of its atmosphere, $M_{\rm atm}$.
Explicitly, we find the relation $T_{\rm eff}\propto M_{\rm atm}^{1/12}$.
Despite this weak relation, a measurement of the flux at the Wien tail can
constrain the atmospheric mass, at least to within a factor of a few, and
provide useful limits to possible formation scenarios of these planets.
Finally, we constrain the size and composition of Planet Nine by combining our
model with the null results of recent all-sky surveys.


title: The full phase space of a model in the Calogero-Ruijsenaars family

abstract:
  We complete the recent derivation of a Ruijsenaars type system that arises as
a reduction of the natural free system on the Heisenberg double of SU(n,n). The
previous analysis by Marshall focused on a dense open submanifold of the
reduced phase space, and here we describe the full phase space wherein
Liouville integrability of the system holds by construction.


title: N=1 Chern-Simons-matter theory and localization

abstract:
  We consider the most general, classically-conformal, three-dimensional
$\mathcal{N}=1$ Chern-Simons-matter theory with global symmetry $Sp(2)$ and
gauge group $U(N)\times U(N)$. We show that the Lagrangian in the on-shell
formulation of the theory admits one more free parameter as compared to the
theory formulated in off-shell $\mathcal{N}=1$ superspace. The theory on $T^3$
can be formally localized. We partially carry out the localization procedure
for the theory on $T^3$ with periodic boundary conditions. In particular we
show that restricting to the saddle points with vanishing gauge connection
gives a trivial contribution to the partition function, i.e. the bosonic and
fermionic contributions exactly cancel each other.


title:
Theoretical modeling of critical temperature increase in metamaterial
  superconductors

abstract:
  Recent experiments have demonstrated that the metamaterial approach is
capable of drastic increase of the critical temperature Tc of epsilon near zero
(ENZ) metamaterial superconductors. For example, tripling of the critical
temperature has been observed in Al-Al2O3 ENZ core-shell metamaterials. Here,
we perform theoretical modelling of Tc increase in metamaterial superconductors
based on the Maxwell-Garnett approximation of their dielectric response
function. Good agreement is demonstrated between theoretical modelling and
experimental results in both aluminium and tin-based metamaterials. Taking
advantage of the demonstrated success of this model, the critical temperature
of hypothetic niobium, MgB2 and H2S-based metamaterial superconductors is
evaluated. The MgB2-based metamaterial superconductors are projected to reach
the liquid nitrogen temperature range. In the case of an H2S-based metamaterial
Tc appears to reach ~250K.


title: Novel chemistry of lithium oxides and superconducting low-pressure LiO4

abstract:
  We study the stability of Li-O compounds as a function of pressure, with Li
ion battery applications and fundamental chemical interest in mind. Using the
ab initio evolutionary algorithm, we predict stability of novel compounds LiO4,
Li5O3 and Li6O under pressure. LiO4, formed at the pressure of just 6 GPa, can
be seen as {\epsilon}-O8 accepting two electrons from two Li atoms. This phase
is superconducting, with Tc up to 12.2 K at 10 GPa. This is remarkable, because
elemental oxygen becomes superconducting at much higher pressure (96 GPa) and
has much lower Tc (<0.6 K), and suggests that chemical alloying with other
elements has the potential of not only decreasing metallization pressure, but
also of increasing Tc. Since {\epsilon}-O8 is called red oxygen, LiO4 can be
identified "lithium red-oxid", and is distinct from superoxide. Additionally,
Li5O3 is stable at pressures above 70 GPa and can be represented as a hybrid
structure 4Li2O {\cdot} Li2O2, and electride suboxide Li6O is stable above 62
GPa.


title:
Nonmagnetic band gap at the Dirac point of the magnetic topological
  insulator (Bi$_{1-x}$Mn$_x)_2$Se$_3$

abstract:
  Magnetic doping is expected to open a band gap at the Dirac point of
topological insulators by breaking time-reversal symmetry and to enable novel
topological phases. Epitaxial (Bi$_{1-x}$Mn$_{x}$)$_{2}$Se$_{3}$ is a
prototypical magnetic topological insulator with a pronounced surface band gap
of $\sim100$ meV. We show that this gap is neither due to ferromagnetic order
in the bulk or at the surface nor to the local magnetic moment of the Mn,
making the system unsuitable for realizing the novel phases. We further show
that Mn doping does not affect the inverted bulk band gap and the system
remains topologically nontrivial. We suggest that strong resonant scattering
processes cause the gap at the Dirac point and support this by the observation
of in-gap states using resonant photoemission. Our findings establish a novel
mechanism for gap opening in topological surface states which challenges the
currently known conditions for topological protection.


title:
A Fenchel-Moreau-Rockafellar type theorem on the Kantorovich-Wasserstein
  space with Applications in Partially Observable Markov Decision Processes

abstract:
  By using the fact that the space of all probability measures with finite
support can be somehow completed in two different fashions, one generating the
Arens-Eells space and another generating the Kantorovich-Wasserstein
(Wasserstein-1) space, and by exploiting the duality relationship between the
Arens-Eells space with the space of Lipschitz functions, we provide a dual
representation of Fenchel-Moreau-Rockafellar type for proper convex functionals
on Wasserstein-1. We retrieve dual transportation inequalities as a Corollary
and we provide examples where the theorem can be used to easily prove dual
expressions like the celebrated Donsker-Varadhan variational formula. Finally
our result allows to write convex functions as the supremum over all linear
functions that are generated by roots of its conjugate dual, something that we
apply to the field of Partially observable Markov decision processes (POMDPs)
to approximate the value function of a given POMDP by iterating level sets.
This extends the method used in Smallwood 1973 for finite state spaces to the
case were the state space is a Polish metric space.


title:
Studying the applicability of different thermoelectric materials for
  efficiency calculation in hybrid thermoelectric generator for waste heat
  recovery from automobile and steel industry

abstract:
  In this work, we study the suitability of different thermoelectric materials
like $Bi_2Te_3$, $Sb_{2}Te_{3}$, $PbTe$, $TAGS$, $CeFe_{4}Sb_{12}$, $SiGe$ and
$TiO_{1.1}$ in estimation of thermoelectric generator's (TEG) efficiency. The
efficiency of TEG made up of ${Be_{2}Te_{3}}$ or $Sb_{2}Te_{3}$ gives $\sim$7\%
in temperature range of 310 K - 500 K. $PbTe$ or $TAGS$ or $CeFe_{4}Sb_{12}$
gives $\sim$6\% in temperature range of 500 K - 900 K and $SiGe$ or $TiO_{1.1}$
also have remarkable efficiency in higher temperature range i.e $\sim$1200 K.
Here, we report the enhancement of efficiency by using hybridization technique
for different combination of above-mentioned materials. Hybridization of two
different materials of TEG module is done by considering compatibility factor
aspect. To this end, the proposed values of overall efficiency of TEG by
hybridizing ${Be_{2}Te_{3}}$ and $PbTe$; ${Be_{2}Te_{3}}$ and $TAGS$;
$Bi_{2}Te_{3}$ and $CeFe_{4}Sb_{12}$ are 12\%, 14\% and 11.88\%, respectively,
for temperature range of 310 K to 900 K, which can be installed in an
automobile. For steel industry and spacecraft application (till 1200 K)
hybridization of $Bi_{2}Te_{3}$, $PbTe$ and $SiGe$; ${Be_{2}Te_{3}}$ and
$TiO_{1.1}$ yields efficiency of $\sim$15.2\% and $\sim$17.2\%, respectively.
The proposed results can be treated as a viable option for engineers, who are
looking for fabricating TEG in real life applications such as automobile,
spacecraft and steel industry.


title: Filtrations of dc-weak eigenforms

abstract:
  The notions of strong, weak and dc-weak eigenforms mod $p^n$ was introduced
and studied by Chen, Kiming and Wiese. In this work, we prove that there can be
no uniform weight bound (that is, depending only on $p$, $n$) on dc-weak
eigenforms mod $p^n$ of fixed level when $n \geq 2$. This is in contrast with
the result of Kiming, Rustom and Wiese which establishes a uniform weight bound
on strong eigenforms mod $p^n$. As a step towards studying weights bounds for
weak eigenforms mod $p^n$, we provide a criterion which allows us to detect
whether a given dc-weak eigenform mod $p^n$ is weak.


title:
Virial series for inhomogeneous fluids applied to the Lennard-Jones
  wall-fluid surface tension at planar and curved walls

abstract:
  We formulate a straightforward scheme of statistical mechanics for
inhomogeneous systems that includes the virial series in powers of the activity
for the grand free energy and density distributions. There, cluster integrals
formulated for inhomogeneous systems play a main role. We center on second
order terms that were analyzed in the case of hard-wall confinement, focusing
in planar, spherical and cylindrical walls. Further analysis was devoted to the
Lennard-Jones system and its generalization the 2k-k potential. For this
interaction potentials the second cluster integral was evaluated analytically.
We obtained the fluid-substrate surface tension at second order for the planar,
spherical and cylindrical confinement. Spherical and cylindrical cases were
analyzed using a series expansion in the radius including higher order terms.
We detected a $\ln R^{-1}/R^{2}$ dependence of the surface tension for the
standard Lennard-Jones system confined by spherical and cylindrical walls, no
matter if particles are inside or outside of the hard-walls. The analysis was
extended to bending and Gaussian curvatures, where exact expressions were also
obtained.


title:
A portable platform for accelerated PIC codes and its application to
  GPUs using OpenACC

abstract:
  We present a portable platform, called PIC_ENGINE, for accelerating
Particle-In-Cell (PIC) codes on heterogeneous many-core architectures such as
Graphic Processing Units (GPUs). The aim of this development is efficient
simulations on future exascale systems by allowing different parallelization
strategies depending on the application problem and the specific architecture.
To this end, this platform contains the basic steps of the PIC algorithm and
has been designed as a test bed for different algorithmic options and data
structures. Among the architectures that this engine can explore, particular
attention is given here to systems equipped with GPUs. The study demonstrates
that our portable PIC implementation based on the OpenACC programming model can
achieve performance closely matching theoretical predictions. Using the Cray
XC30 system, Piz Daint, at the Swiss National Supercomputing Centre (CSCS), we
show that PIC_ENGINE running on an NVIDIA Kepler K20X GPU can outperform the
one on an Intel Sandybridge 8-core CPU by a factor of 3.4.


title: A Characterization of regular points by $L^2$ Extension Theorem

abstract:
  In this article, we present that the germ of a complex analytic set at the
origin in $\mathbb{C}^n$ is regular if and only if the related $L^2$ extension
theorem holds. We also obtain a necessary condition of the $L^2$ extension of
bounded holomorphic sections from singular analytic sets.


title:
From local to hydrodynamic friction in Brownian motion: A multiparticle
  collision dynamics simulation study

abstract:
  The friction and diffusion coefficients of rigid spherical colloidal
particles dissolved in a fluid are determined from velocity and force
autocorrelation functions by mesoscale hydrodynamic simulations. Colloids with
both slip and no-slip boundary conditions are considered, which are embedded in
fluids modelled by multiparticle collision dynamics (MPC) with and without
angular momentum conservation. For no-slip boundary conditions, hydrodynamics
yields the well-known Stokes law, while for slip boundary conditions the lack
of angular momentum conservation leads to a reduction of the hydrodynamic
friction coefficient compared to the classical result. The colloid diffusion
coefficient is determined by integration of the velocity autocorrelation
function, where the numerical result at shorter times is combined with the
theoretical hydrodynamic expression for longer times. The suitability of this
approach is confirmed by simulations of sedimenting colloids. In general, we
find only minor deviations from the Stokes-Einstein relation, which even
disappear for larger colloids. Importantly, for colloids with slip boundary
conditions, our simulation results contradict the frequently assumed additivity
of local and hydrodynamic diffusion coefficients.


title: Quantum quenches in 1+1 dimensional conformal field theories

abstract:
  We review the imaginary time path integral approach to the quench dynamics of
conformal field theories. We show how this technique can be applied to the
determination of the time dependence of correlation functions and entanglement
entropy for both global and local quenches. We also briefly review other quench
protocols. We carefully discuss the limits of applicability of these results to
realistic models of condensed matter and cold atoms.


title: A polynomial analogue of Landau's theorem and related problems

abstract:
  Recently, an analogue over $\mathbb{F}_q[T]$ of Landau's theorem on sums of
two squares was considered by Bary-Soroker, Smilansky and Wolf. They counted
the number of monic polynomials in $\mathbb{F}_q[T]$ of degree $n$ of the form
$A^2+TB^2$, which we denote by $B(n,q)$. They studied $B(n,q)$ in two limits:
fixed $n$ and large $q$; and fixed $q$ and large $n$. We generalize their
result to the most general limit $q^n \to \infty$. More precisely, we prove
\begin{equation*} B(n,q) \sim K_q \cdot \binom{n-\frac{1}{2}}{n} \cdot q^n ,
\qquad q^n \to \infty, \end{equation*} for an explicit constant $K_q =
1+O\left(1/q\right)$. Our methods are different and are based on giving
explicit bounds on the coefficients of generating functions. These methods also
apply to other problems, related to polynomials with prime factors of even
degree.


title: Fast radio bursts as giant pulses from young rapidly rotating pulsars

abstract:
  We discuss possible association of fast radio bursts (FRBs) with supergiant
pulses emitted by young pulsars (ages $\sim$ tens to hundreds of years) born
with regular magnetic field but very short -- few milliseconds -- spin periods.
FRBs are extra-Galactic events coming from distances $d \lesssim 100$ Mpc. Most
of the dispersion measure (DM) comes from the material in the freshly ejected
SNR shell; for a given burst the DM should decrease with time. FRBs are not
expected to be seen below $\sim 300 $ MHz due to free-free absorption in the
expanding ejecta. A supernova might have been detected years before the burst;
FRBs are mostly associated with star forming galaxies.
  The model requires that some pulsars are born with very fast spins, of the
order of few milliseconds. The observed distribution of spin-down powers
$\dot{E}$ in young energetic pulsars is consistent with equal birth rate per
decade of $\dot{E}$. Accepting this injection spectrum and scaling the
intrinsic brightness of FRBs with $\dot{E}$, we predict the following
properties of a large sample of FRBs: (i) the brightest observed events come
from a broad distribution in distances; (ii) for repeating bursts brightness
either remains nearly constant (if the spin-down time is longer than the age of
the pulsar) or decreases with time otherwise; in the latter case DM $\propto
\dot{E}$.


title: Superconductivity at 9K in Mo5PB2 with evidence for multiple gaps

abstract:
  Superconductivity is observed with critical temperatures near 9K in the
tetragonal compound Mo5PB2. This material adopts the Cr5B3 structure type
common to supercondcuting Nb5Si3-xBx, Mo5SiB2, and W5SiB2, which have critical
temperatures of 5.8-7.8 K. We have synthesized polycrystalline samples of the
compound, made measurements of electrical resistivity, magnetic susceptibility,
and heat capacity, and performed first principles electronic structure
calculations. The highest Tc value (9.2 K) occurs in slightly phosphorus rich
samples, with composition near Mo5P1.1B1.9, and the upper critical field Hc2 at
T = 0 is estimated to be about 17 kOe. Together, the measurements and band
structure calculations indicate intermediate coupling (lambda = 1.0), phonon
mediated superconductivity. The temperature dependence of the heat capacity and
upper critical field Hc2 below Tc suggest multiple superconducting gaps may be
present.


title: On the virtual Rasmussen invariant

abstract:
  We produce chain-level generators of the virtual Lee complex $ Kh ' (V ) $
and use them to convert the computable bounds on the Rasmussen invariant of
classical knots due to Kawamura and Lobb into bounds on the virtual Rasmussen
invariant as defined by Dye, Kaestner, and Kauffman. We also exhibit a class of
diagrams for which the bounds are tight. In addition, we use the chain-level
generators to show that the virtual Rasmussen invariant is additive with
respect to connect sum.


title:
HATS-11b and HATS-12b: Two transiting Hot Jupiters orbiting sub-solar
  metallicity stars selected for the K2 Campaign 7

abstract:
  We report the discovery of two transiting extrasolar planets from the
HATSouth survey. HATS-11, a V=14.1 G0-star shows a periodic 12.9 mmag dip in
its light curve every 3.6192 days and a radial velocity variation consistent
with a Keplerian orbit. HATS-11 has a mass of 1.000 $\pm$ 0.060 M$_{\odot}$, a
radius of 1.444 $\pm$ 0.057 M$_{\odot}$ and an effective temperature of 6060
$\pm$ 150 K, while its companion is a 0.85 $\pm$ 0.12 M$_J$, 1.510 $\pm$ 0.078
R$_J$ planet in a circular orbit. HATS-12 shows a periodic 5.1 mmag flux
decrease every 3.1428 days and Keplerian RV variations around a V=12.8 F-star.
HATS-12 has a mass of 1.489 $\pm$ 0.071 M$_{\odot}$, a radius of 2.21 $\pm$
0.21 R$_{\odot}$, and an effective temperature of 6408 $\pm$ 75 K. For HATS-12,
our measurements indicate that this is a 2.38 $\pm$ 0.11 M$_J$, 1.35 $\pm$ 0.17
R$_J$ planet in a circular orbit. Both host stars show sub-solar metallicity of
-0.390 $\pm$ 0.060 dex and -0.100 $\pm$ 0.040 dex, respectively and are
(slightly) evolved stars. In fact, HATS-11 is amongst the most metal-poor and,
HATS-12 is amongst the most evolved stars hosting a hot Jupiter planet.
Importantly, HATS-11 and HATS-12 have been observed in long cadence by Kepler
as part of K2 campaign 7 (EPIC216414930 and EPIC218131080 respectively).


title:
Performance Analysis of Multi-Hop Underwater Wireless Optical
  Communication Systems (Extended Version)

abstract:
  In this paper, we evaluate the end-to-end bit error rate (BER) of
point-to-point underwater wireless optical communication (UWOC) systems with
multi-hop transmission. To do so, we analytically derive the BER expression of
a single-hop UWOC link as the building block for end-to-end BER evaluation. We
also apply photon-counting method to evaluate the system BER in the presence of
shot noise. Moreover, we use Gauss-Hermite quadrature formula to obtain the
closed-form solutions for the system BER in the case of log-normal underwater
fading channels. Our analytical treatment involves all the impairing effects of
the underwater optical channel, namely absorption, scattering and fading.
Numerical results demonstrate that multi-hop transmission by alleviating the
aforementioned impairing effects of the channel, can significantly improve the
system performance and extend the viable end-to-end communication distance. For
example, dual-hop transmission in $22.5$ m and $45$ m coastal water links can
provide $17.5$ dB and $39$ dB performance enhancement at the BER of $10^{-6}$,
respectively.


title:
Small-time asymptotics for basket options -- the bi-variate SABR model
  and the hyperbolic heat kernel on $\mathbb{H}^3$

abstract:
  We compute a sharp small-time estimate for the price of a basket call under a
bi-variate SABR model with both $\beta$ parameters equal to $1$ and three
correlation parameters, which extends the work of Bayer,Friz&Laurence [BFL14]
for the multivariate Black-Scholes flat vol model. The result follows from the
heat kernel on hyperbolic space for $n=3$ combined with the Bellaiche [Bel81]
heat kernel expansion and Laplace's method, and we give numerical results which
corroborate our asymptotic formulae. Similar to the Black-Scholes case, we find
that there is a phase transition from one "most-likely" path to two most-likely
paths beyond some critical $K^*$.


title:
Direct measurement of desorption and diffusion energies of O and N atoms
  physisorbed on amorphous surfaces

abstract:
  Physisorbed atoms on the surface of interstellar dust grains play a central
role in solid state astrochemistry. Their surface reactivity is one source of
the observed molecular complexity in space. In experimental astrophysics, the
high reactivity of atoms also constitutes an obstacle to measuring two of the
fundamental properties in surface physics, namely desorption and diffusion
energies, and so far direct measurements are non-existent for O and N atoms. We
investigated the diffusion and desorption processes of O and N atoms on cold
surfaces in order to give boundary conditions to astrochemical models. Here we
propose a new technique for directly measuring the N- and O-atom mass signals.
Including the experimental results in a simple model allows us to almost
directly derive the desorption and diffusion barriers of N atoms on amorphous
solid water ice (ASW) and O atoms on ASW and oxidized graphite. We find a
strong constraint on the values of desorption and thermal diffusion energy
barriers. The measured barriers for O atoms are consistent with recent
independent estimations and prove to be much higher than previously believed
(E$_{des}=1410_{-160}^{+290}$; E$_{dif}=990_{-360}^{+530}$ K on ASW). As for
oxygen atoms, we propose that the combination E$_{des}$-E$_{dif}$=1320-750 K is
a sensible choice among the possible pairs of solutions. Also, we managed to
measure the desorption and diffusion energy of N atoms for the first time
(E$_{des}=720_{-80}^{+160}$; E$_{dif}=525_{-200}^{+260}$ K on ASW) in the
thermal hopping regime and propose that the combination
E$_{des}$-E$_{dif}$=720-400 K can be reasonably adopted in models. The value of
E$_{dif}$ for N atoms is slightly lower than previously suggested, which
implies that the N chemistry on dust grains might be richer.


title:
Frequency Modulation of Directly Imaged Exoplanets: Geometric Effect as
  a Probe of Planetary Obliquity

abstract:
  We consider the time-frequency analysis of a scattered light curve of a
directly imaged exoplanet. We show that the geometric effect due to planetary
obliquity and orbital inclination induce the frequency modulation of the
apparent diurnal periodicity. We construct a model of the frequency modulation
and compare it with the instantaneous frequency extracted from the
pseudo-Wigner distribution of simulated light curves of a cloudless Earth. The
model provides good agreement with the simulated modulation factor, even for
the light curve with Gaussian noise comparable to the signal. Notably, the
shape of the instantaneous frequency is sensitive to the difference between the
prograde, retrograde, and pole-on spin rotations. While our technique requires
the albedo map to be static, it does not need to solve the albedo map of the
planet. The time-frequency analysis is complementary to other methods which
utilize the amplitude modulation. This paper demonstrates the importance of the
frequency domain of the photometric variability for the characterization of
directly imaged exoplanets in future research.


title: On dust entrainment in photoevaporative winds

abstract:
  We investigate dust entrainment by photoevaporative winds in protoplanetary
discs using dusty smoothed particle hydrodrodynamics (SPH). We use unequal-mass
particles to resolve more than five orders of magnitude in disc/outflow density
and a one-fluid formulation to efficiently simulate an equivalent magnitude
range in drag stopping time. We find that only micron sized dust grains and
smaller can be entrained in EUV driven winds. The maximum grain size is set by
dust settling in the disc rather than aerodynamic drag in the wind. More
generally, there is a linear relationship between the base flow density and the
maximum entrainable grain size in the wind. A pileup of micron sized dust
grains can occur in the upper atmosphere at critical radii in the disc as
grains decouple from the low-density wind. Entrainment is a strong function of
location in the disc, resulting in a size sorting of grains in the
outflow---the largest grain being carried out between $10$--$20\,$AU. The peak
dust density for each grain size occurs at the inner edge of its own
entrainment region.


title:
Role of CT in the Survival of Small and Medium Scale Enterprises in
  Ghana Evidence from selected Small and Medium Scale Enterprises in New Juaben
  Municipality Koforidua

abstract:
  This study is to examine the role of ICT in the survival of selected SMEs in
Koforidua, Ghana The study employed descriptive technique to conduct the
survey. Using a sample of 100 SMEs, an accidental sampling of a non-probability
technique was used to gathered data and information. The study argues out that
majority of the SMEs operators do use at least one ICT tool in supporting their
operations within the New Juaben Municipality. The study revealed that ICT is
good and helps business survival in difficult times and become competitive in
support of literature r ;eviewed. The study suggested that periodic training in
the form of workshops and sensitization programs on the benefits and the use
ICT resources in business growth strategies should be organized by National
Board for Small-Scale Industries (NBSSI). SME operators, can also outsource
their ICT delivery systems by engaging ICT consultants in order to avoid the
problem of funding relating to the setting up of their own ICT system which
usually requires huge initial capital outlay. The primary policy recommendation
arising out of this is that applications for SMEs need to be developed using
mobile phones.


title: Linear Extensions and Comparable Pairs in Partial Orders

abstract:
  We study the number of linear extensions of a partial order with a given
proportion of comparable pairs of elements, and estimate the maximum and
minimum possible numbers. We also consider a random interval partial order on
$n$ elements, which has close to a third of the pairs comparable with high
probability: we show that the number of linear extensions is $n! \,
2^{-\Theta(n)}$ with high probability.


title: Interacting Default Intensity with Hidden Markov Process

abstract:
  In this paper we consider a reduced-form intensity-based credit risk model
with a hidden Markov state process. A filtering method is proposed for
extracting the underlying state given the observation processes. The method may
be applied to a wide range of problems. Based on this model, we derive the
joint distribution of multiple default times without imposing stringent
assumptions on the form of default intensities. Closed-form formulas for the
distribution of default times are obtained which are then applied to solve a
number of practical problems such as hedging and pricing credit derivatives.
The method and numerical algorithms presented may be applicable to various
forms of default intensities.


title: Duality in N=4 Liouville Theory and Moonshine Phenomena

abstract:
  We consider the ${\cal N}=4$ Liouville theory by varying the linear dilaton
coupling constant $\cal{Q}$. It is known that at two different values of
coupling constant ${\cal Q}=\sqrt{{2\over N}},-(N-1)\sqrt{{2\over N}}$ system
exhibits two different small ${\cal N}=4$ superconformal symmetries with
central charge $c=6$ and $c=6(N-1)$, respectively. In the context of string
theory these two theories are considered to describe Coulumb and Higgs branch
of the theory and expected to be dual to each other. We study the Mathieu and
umbral moonshine phenomena in these two theories and discuss their dual
description. We mainly consider the case of $A_N$ type modular invariants.