title:
Multiscale simulations of anisotropic particles combining Brownian
  Dynamics and Green's Function Reaction Dynamics

abstract:
  The modeling of complex reaction-diffusion processes in, for instance,
cellular biochemical networks or self-assembling soft matter can be
tremendously sped up by employing a multiscale algorithm which combines the
mesoscopic Green's Function Reaction Dynamics (GFRD) method with explicit
stochastic Brownian, Langevin, or deterministic Molecular Dynamics to treat
reactants at the microscopic scale [A. Vijaykumar, P.G. Bolhuis and P.R. ten
Wolde, J. Chem. Phys. {\bf 43}, 21: 214102 (2015)]. Here we extend this
multiscale BD-GFRD approach to include the orientational dynamics that is
crucial to describe the anisotropic interactions often prevalent in
biomolecular systems. We illustrate the novel algorithm using a simple patchy
particle model. After validation of the algorithm we discuss its performance.
The rotational BD-GFRD multiscale method will open up the possibility for large
scale simulations of e.g. protein signalling networks.


title:
Linear vs Nonlinear MPC for Trajectory Tracking Applied to Rotary Wing
  Micro Aerial Vehicles

abstract:
  Precise trajectory tracking is a crucial property for \acp{MAV} to operate in
cluttered environment or under disturbances. In this paper we present a
detailed comparison between two state-of-the-art model-based control techniques
for \ac{MAV} trajectory tracking. A classical \ac{LMPC} is presented and
compared against a more advanced \ac{NMPC} that considers the full system
model. In a careful analysis we show the advantages and disadvantages of the
two implementations in terms of speed and tracking performance. This is
achieved by evaluating hovering performance, step response, and aggressive
trajectory tracking under nominal conditions and under external wind
disturbances.


title:
Quasilinear parabolic stochastic evolution equations via maximal $ L^{p}
  $-regularity

abstract:
  We study the Cauchy problem for an abstract quasilinear stochastic parabolic
evolution equation on a Banach space driven by a cylindrical Brownian motion.
We prove existence and uniqueness of a local strong solution up to a maximal
stopping time, that is characterised by a blow-up alternative. The key idea is
an iterative application of the theory about maximal $ L^p $- regularity for
semilinear stochastic evolution equations by Van Neerven, Veraar and Weis. We
apply our local well-posedness result to a convection-diffusion equation on a
bounded domain with Dirichlet, Neumann or mixed boudary conditions and to a
generalized Navier-Stokes equation describing non-Newtonian fluids. In the
first example, we can even show that the solution exists globally.


title: Helical propulsion in shear-thinning fluids

abstract:
  Swimming microorganisms often have to propel in complex, non-Newtonian
fluids. We carry out experiments with self-propelling helical swimmers driven
by an externally rotating magnetic field in shear-thinning, inelastic fluids.
Similarly to swimming in a Newtonian fluid, we obtain for each fluid a
locomotion speed which scales linearly with the rotation frequency of the
swimmer, but with a prefactor which depends on the power index of the fluid.
The fluid is seen to always increase the swimming speed of the helix, up to 50%
faster and thus the strongest of such type reported to date. The maximum
relative increase for a fluid power index of around 0.6. Using simple scalings,
we argue that the speed increase is not due to the local decrease of the flow
viscosity around the helical filament but hypothesise instead that it
originates from confinement-like effect due to viscosity stratification around
the swimmer.


title:
Energy-Efficient Resource Allocation for Mobile Edge Computing-Based
  Augmented Reality Applications

abstract:
  Mobile edge computing is a provisioning solution to enable Augmented Reality
(AR) applications on mobile devices. AR mobile applications have inherent
collaborative properties in terms of data collection in the uplink, computing
at the edge, and data delivery in the downlink. In this letter, these features
are leveraged to propose a novel resource allocation approach over both
communication and computation resources. The approach, implemented via
Successive Convex Approximation (SCA), is seen to yield considerable gains in
mobile energy consumption as compared to conventional independent offloading
across users.


title:
A survey of dual active galactic nuclei in simulations of galaxy
  mergers: frequency and properties

abstract:
  We investigate the simultaneous triggering of active galactic nuclei (AGN) in
merging galaxies, using a large suite of high-resolution hydrodynamical
simulations. We compute dual-AGN observability time-scales using bolometric,
X-ray, and Eddington-ratio thresholds, confirming that dual activity from
supermassive black holes (BHs) is generally higher at late pericentric
passages, before a merger remnant has formed, especially at high luminosities.
For typical minor and major mergers, dual activity lasts ~20-70 and ~100-160
Myr, respectively. We also explore the effects of X-ray obscuration from gas,
finding that the dual-AGN time decreases at most by a factor of ~2, and of
contamination from star formation. Using projected separations and velocity
differences rather than three-dimensional quantities can decrease the dual-AGN
time-scales by up to ~4, and we apply filters which mimic current
observational-resolution limitations. In agreement with observations, we find
that, for a sample of major and minor mergers hosting at least one AGN, the
fraction harbouring dual AGN is ~20-30 and ~1-10 per cent, respectively. We
quantify the effects of merger mass ratio (0.1 to 1), geometry (coplanar,
prograde, retrograde, and inclined), disc gas fraction, and BH properties,
finding that the mass ratio is the most important factor, with the difference
between minor and major mergers varying between factors of a few to orders of
magnitude, depending on the luminosity and filter used. We also find that a
shallow imaging survey will require very high angular resolution, whereas a
deep imaging survey will be less resolution-dependent.


title: Evolving Network Model that Almost Regenerates Epileptic Data

abstract:
  In many realistic networks, the edges representing the interactions between
the nodes are time-varying. There is growing evidence that the complex network
that models the dynamics of the human brain has time-varying interconnections,
i.e., the network is evolving. Based on this evidence, we construct a patient
and data specific evolving network model (comprising discrete-time dynamical
systems) in which epileptic seizures or their terminations in the brain are
also determined by the nature of the time-varying interconnections between the
nodes. A novel and unique feature of our methodology is that the evolving
network model remembers the data from which it was conceived from, in the sense
that it evolves to almost regenerate the patient data even upon presenting an
arbitrary initial condition to it. We illustrate a potential utility of our
methodology by constructing an evolving network from clinical data that aids in
identifying an approximate seizure focus -- nodes in such a theoretically
determined seizure focus are outgoing hubs that apparently act as spreaders of
seizures. We also point out the efficacy of removal of such spreaders in
limiting seizures.


title: Some Aspects of FELWI

abstract:
  A threshold condition for amplification without inversion in a free-electron
laser without inversion (FELWI) is determined. This condition is found to be
too severe for the effect to be observed in an earlier suggested scheme because
a threshold intensity of the field to be amplified appears to be too high. This
indicates that alternative schemes have to be found for making the creation of
an FELWI realistic.


title:
On the IceCube Result on $\bar{\nu}_{\mu} \to \bar{\nu}_{s}$
  Oscillations

abstract:
  We elucidate the mechanism of enhancement of the $\bar{\nu}_{\mu} \to
\bar{\nu}_{s}$ transitions at small mixing angles of Earth-core-crossing
neutrinos, which is at the basis of the recent result of the IceCube experiment
on atmospheric muon anti-neutrino oscillations into sterile anti-neutrino.


title: An upper bound on quantum capacity of unital channels

abstract:
  We analyze the quantum capacity of a unital quantum channel, using ideas from
the proof of near-optimality of Petz recovery map [Barnum and Knill 2000] and
give an upper bound on the quantum capacity in terms of regularized output
$2$-norm of the channel. We also show that any code attempting to exceed this
upper bound must incur large error in decoding, which can be viewed as a weaker
version of the strong converse results for quantum capacity. As an application,
we find nearly matching upper and lower bounds (up to an additive constant) on
the quantum capacity of quantum expander channels. Using these techniques, we
further conclude that the `mixture of random unitaries' channels arising in the
construction of quantum expanders in [Hastings 2007] show a trend in
multiplicativity of output $2$-norm similar to that exhibited in [Montanaro
2013] for output $\infty$-norm of random quantum channels.


title: The Nonlinear Theory of FEL

abstract:
  The nonlinear theory of relyativistic strophotron is developed. Classical
equations of motion are averaged over fast oscillations. The slow motion phase
and saturation parameter are found different from usual undulator oscillation
parameters. In the strong field approximation the analytical expression of gain
is found on higher harmonics of main resonance frequency.


title: The $q-$Onsager algebra and multivariable $q-$special functions

abstract:
  Two sets of mutually commuting $q-$difference operators $x_i$ and $y_j$,
$i,j=1, ...,N$ such that $x_i$ and $y_i$ generate a homomorphic image of the
$q-$Onsager algebra for each $i$ are introduced. The common polynomial
eigenfunctions of each set are found to be entangled product of elementary
Pochhammer functions in $N$ variables and $N+3$ parameters. Under certain
conditions on the parameters, they form two `dual' bases of polynomials in $N$
variables. The action of each operator with respect to its dual basis is block
tridiagonal. The overlap coefficients between the two dual bases are expressed
as entangled products of $q-$Racah polynomials and satisfy an orthogonality
relation. The overlap coefficients between either one of these bases and the
multivariable monomial basis are also considered. One obtains in this case
entangled products of dual $q-$Krawtchouk polynomials. Finally, the `split'
basis in which the two families of operators act as block bidiagonal matrices
is also provided.


title:
Monotone Dynamical Systems with Polyhedral Order Cones and Dense
  Periodic Points

abstract:
  Let X be a subset of R^n whose interior is connected and dense in X, ordered
by a polyhedral cone in R^n with nonempty interior. Let T be a monotone
homeomorphism of X whose periodic points are dense. Then T is periodic.


title: Fast Mixing Random Walks and Regularity of Incompressible Vector Fields

abstract:
  We show sufficient conditions under which the \textsc{BallWalk} algorithm
mixes fast in a bounded connected subset of $\Real^n$. In particular, we show
fast mixing if the space is the transformation of a convex space under a smooth
incompressible flow. Construction of such smooth flows is in turn reduced to
the study of the regularity of the solution of the Dirichlet problem for
Laplace's equation.


title:
Amplitude analysis of $D^{0} \rightarrow \pi^{+} \pi^{-} \pi^{+}
  \pi^{-}$ decays using CLEO-c data

abstract:
  The resonant substructure of the decay $D^{0} \rightarrow \pi^{+} \pi^{-}
\pi^{+} \pi^{-}$ is studied by performing a full five-dimensional amplitude
analysis. Preliminary results based on data collected by the CLEO-c detector
are presented. This is the largest dataset of $D^{0} \rightarrow \pi^{+}
\pi^{-} \pi^{+} \pi^{-}$ decays analysed in this way to-date. The two most
significant contributions are $D^{0} \rightarrow a_{1}(1260)^{+} \pi^{-}$ and
$D^{0} \rightarrow \rho(770)^{0}\rho(770)^{0}$. The line shape, mass and width
of the $a_{1}(1260)$ resonance are determined, and model-independent studies of
the line shapes of several resonant contributions are preformed.


title: Phase transitions triggered by dumbbell equipotential hypersurfaces

abstract:
  In a recent paper a toy model (called hypercubic model) undergoing a
first-order $\mathbb{Z}_2$ symmetry breaking phase transition (SBPT) has been
introduced. The hypercubic model was inspired by the \emph{topological
hypothesis}, according to which a phase transition may be entailed by suitable
topological changes of the equipotential hypersurfaces $\Sigma_v$ of
configuration space. The $\Sigma_v$'s of the hypercubic model have a single
topological change, which, under further particular hypotheses of geometric
nature, entails the $\mathbb{Z}_2$-SBPT. In this paper we introduce an extended
version of the hypercubic model in which no topological change in the
$\Sigma_v$'s is present anymore, but nevertheless the $\mathbb{Z}_2$-SBPT
occurs the same. We introduce a geometric property of the $\Sigma_v$'s (i.e.
dumbbell $\Sigma_v$'s suitably defined) that is sufficient to entail a
$\mathbb{Z}_2$-SBPT regardless their topology. The paper ends by applying the
picture of the dumbbell $\Sigma_v$'s to a physical model, i.e. the mean-field
$\phi^4$ model.


title:
Well-posedness and nonlinear smoothing for the "good" Boussinesq
  equation on the half-line

abstract:
  In this paper we study the regularity properties of the "good" Boussinesq
equation on the half line. We obtain local existence, uniqueness and continuous
dependence on initial data in low-regularity spaces. Moreover we prove that the
nonlinear part of the solution on the half line is smoother than the initial
data, obtaining half derivative smoothing of the nonlinear term in some cases.
Our paper improves the result in [Himonas-Mantzavinos 2015], being the first
result that constructs solutions for the initial and boundary value problem of
the "good" Boussinesq equation below the $L^2$ space. Our theorems are sharp
within the framework of the restricted norm method that we use and match the
known results on the full line in [Kenig-Ponce-Vega 1996] and [Farah 2009].


title:
Rotating Bose-Einstein condensates with a finite number of atoms
  confined in a ring potential: Spontaneous symmetry breaking, beyond the
  mean-field approximation

abstract:
  Motivated by recent experiments on Bose-Einstein condensed atoms which rotate
in annular/toroidal traps we study the effect of the finiteness of the atom
number $N$ on the states of lowest energy for a fixed expectation value of the
angular momentum, under periodic boundary conditions. To attack this problem,
we develop a general strategy, considering a linear superposition of the
eigenstates of the many-body Hamiltonian, with amplitudes that we extract from
the mean field approximation. This many-body state breaks the symmetry of the
Hamiltonian, it has the same energy to leading order in $N$ as the mean-field
state and the corresponding eigenstate of the Hamiltonian, however it has a
lower energy to subleading order in $N$ and thus it is energetically favorable.


title: Massive Star Formation in the LMC. I. N159 and N160 Complexes

abstract:
  We present images and spectral energy distributions (SEDs) of massive young
stellar objects (YSOs) in three star-forming H II regions of the Large
Magellanic Cloud: N159A, N159 Papillon, and N160. We use photometry from
SOFIA/FORCAST at 25.3--37.1 um to constrain model fits to the SEDs and
determine luminosities, ages, and dust content of the embedded YSOs and their
local environments. By placing these sources on mid-infrared color-magnitude
and color-color diagrams, we analyze their dust properties and consider their
evolutionary status. Since each object in the FORCAST images has an obvious
bright near-infrared counterpart in Spitzer Space Telescope images, we do not
find any evidence for new, very cool, previously-undiscovered Class 0 YSOs.
Additionally, based on its mid-infrared colors and model parameters, N159A is
younger than N160 and the Papillon. The nature of the first extragalactic
protostars in N159, P1 and P2, is also discussed.


title:
Local Langlands correspondence and ramification for Carayol
  representations

abstract:
  Let $F$ be a non-Archimedean locally compact field of residual characteristic
$p$ with Weil group $\Cal W_F$. Let $\sigma$ be an irreducible smooth complex
representation of $\Cal W_F$, realized as the Langlands parameter of an
irreducible cuspidal representation $\pi$ of a general linear group over $F$.
In an earlier paper, we showed that the ramification structure of $\sigma$ is
determined by the fine structure of the endo-class $\varTheta$ of the simple
character contained in $\pi$, in the sense of Bushnell-Kutzko. The connection
is made via the {\it Herbrand function} $\Psi_\varTheta$ of $\varTheta$. In
this paper, we concentrate on the fundamental Carayol case in which $\sigma$ is
totally wildly ramified with Swan exponent not divisible by $p$. We show that,
for such $\sigma$, the associated Herbrand function satisfies a certain
symmetry condition or functional equation, a property that essentially
characterizes this class of representations. We calculate $\Psi_\varTheta$
explicitly, in terms of a classical Herbrand function coming from the
Bushnell-Kutzko classification of simple characters. We describe exactly the
class of functions arising as Herbrand functions $\Psi_\varXi$, as $\varXi$
varies over totally wild endo-classes of Carayol type. In a separate argument,
we get a complete description of $\sigma$ restricted to any ramification
subgroup. This provides a different, more Galois-centred, view on
$\Psi_\varTheta$.


title: Do be do be do

abstract:
  We explore the design and implementation of Frank, a strict functional
programming language with a bidirectional effect type system designed from the
ground up around a novel variant of Plotkin and Pretnar's effect handler
abstraction.
  Effect handlers provide an abstraction for modular effectful programming: a
handler acts as an interpreter for a collection of commands whose interfaces
are statically tracked by the type system. However, Frank eliminates the need
for an additional effect handling construct by generalising the basic mechanism
of functional abstraction itself. A function is simply the special case of a
Frank operator that interprets no commands. Moreover, Frank's operators can be
multihandlers which simultaneously interpret commands from several sources at
once, without disturbing the direct style of functional programming with
values.
  Effect typing in Frank employs a novel form of effect polymorphism which
avoid mentioning effect variables in source code. This is achieved by
propagating an ambient ability inwards, rather than accumulating unions of
potential effects outwards.
  We introduce Frank by example, and then give a formal account of the Frank
type system and its semantics. We introduce Core Frank by elaborating Frank
operators into functions, case expressions, and unary handlers, and then give a
sound small-step operational semantics for Core Frank.
  Programming with effects and handlers is in its infancy. We contribute an
exploration of future possibilities, particularly in combination with other
forms of rich type system.


title: The LP-Newton Method and Conic Optimization

abstract:
  We propose that the LP-Newton method can be used to solve conic LPs over a
conic box, whenever linear optimization over an otherwise unconstrained conic
box is easy. In particular, if $\leq_\mathcal{K}$ is the partial order induced
by a proper convex cone $\mathcal{K}$, then optimizing a linear function over
the intersection of $[{l},{u}]_\mathcal{K}=\{{l}\leq_\mathcal{K}
{x}\leq_\mathcal{K}{u}\}$ and an affine subspace can be done with this method
whenever optimizing a linear function over $[{l},{u}]_{\mathcal{K}}$ is
efficient.
  This generalizes the result for the case of $\mathcal{K}=\mathbb{R}^n_+$ that
was originally proposed for using the method. Specifically, we show how to
adapt this method for both SOCP and SDP problems and illustrate the method with
a few experiments. While the approach is promising due to the low amount of
Newton steps needed, solving the minimum-norm-point problem involved in the
Newton step with a Frank-Wolfe algorithm is not advisable.


title: A Technique to Share Multiple Secret Images

abstract:
  Visual Cryptography comes under cryptography domain. It deals with encrypting
and decrypting of visual information like pictures, texts, videos $ etc.$ Multi
Secret Image Sharing (MSIS) scheme is a part of visual cryptography that
provides a protected method to transmit more than one secret images over a
communication channel. Conventionally, transmission of a single secret image is
possible over a channel at a time. But as technology grows, there emerge a need
for sharing more than one secret image. An $(n, n)$-MSIS scheme is used to
encrypt $n$ secret images into $n$ meaningless noisy images that are stored
over different servers. To recover $n$ secret images all $n$ noisy images are
required. At earlier time, the main problem with secret sharing schemes was
that attacker can partially figure out secret images, even by getting access of
$n-1$ or fewer noisy images. To tackle with this security issue, there arises a
need of secure MSIS scheme, so that attacker can not retrieve any information
by using less than $n-1$ noisy images. In this paper, we propose a secure $(n,
n+1)$-MSIS scheme using additive modulo operation for grayscale and colored
images. For checking the effectiveness of proposed scheme; Correlation, MSE and
PSNR techniques are used. The experimental results show that the proposed
scheme is highly secured and altering of noisy images will not reveal any
partial information about secret images. The proposed $(n, n+1)$-MSIS scheme
outperforms the existing MSIS schemes in terms of security.


title:
Stability of gap soliton complexes in the nonlinear Schr\"odinger
  equation with periodic potential and repulsive nonlinearity

abstract:
  The work is devoted to numerical investigation of stability of stationary
localized modes ("gap solitons") for the one-dimentional nonlinear
Schr\"odinger equation (NLSE) with periodic potential and repulsive
nonlinearity. Two classes of the modes are considered: a bound state of a pair
of in-phase and out-of-phase fundamental gap solitons (FGSs) from the first
bandgap separated by various number of empty potential wells. Using the
standard framework of linear stability analysis, we computed the linear spectra
for the gap solitons by means of the Fourier collocation method and the Evans
function method. We found that the gap solitons of the first and second classes
are exponentially unstable for odd and even numbers of separating periods of
the potential, respectively. The real parts of unstable eigenvalues in
corresponding spectra decay with the distance between FGSs exponentially. On
the contrary, we observed that the modes of the first and second classes are
either linearly stable or exhibit weak oscillatory instabilities if the number
of empty potential wells separating FGSs is even and odd, respectively. In both
cases, the oscillatory instabilities arise in some vicinity of upper bandgap
edge. In order to check the linear stability results, we fulfilled numerical
simulations for the time-dependent NLSE by means of a finite-difference scheme.
As a result, all the considered exponentially unstable solutions have been
deformed to long-lived pulsating formations whereas stable solutions conserved
their shapes for a long time.


title: Guarded Cubical Type Theory

abstract:
  This paper improves the treatment of equality in guarded dependent type
theory (GDTT), by combining it with cubical type theory (CTT). GDTT is an
extensional type theory with guarded recursive types, which are useful for
building models of program logics, and for programming and reasoning with
coinductive types. We wish to implement GDTT with decidable type checking,
while still supporting non-trivial equality proofs that reason about the
extensions of guarded recursive constructions. CTT is a variation of
Martin-L\"of type theory in which the identity type is replaced by abstract
paths between terms. CTT provides a computational interpretation of functional
extensionality, enjoys canonicity for the natural numbers type, and is
conjectured to support decidable type-checking. Our new type theory, guarded
cubical type theory (GCTT), provides a computational interpretation of
extensionality for guarded recursive types. This further expands the
foundations of CTT as a basis for formalisation in mathematics and computer
science. We present examples to demonstrate the expressivity of our type
theory, all of which have been checked using a prototype type-checker
implementation. We show that CTT can be given semantics in presheaves on the
product of the cube category and a small category with an initial object. We
then show that the category of presheaves on the product of the cube category
and omega provides semantics for GCTT.


title:
Stellar progenitors of black holes: insights from optical and infrared
  observations

abstract:
  Here are reviewed the insights from observations at optical and infrared
wavelengths for low mass limits above which stars do not seem to end as
luminous supernovae. These insights are: (1) the absence in archived images of
nearby galaxies of stellar progenitors of core-collapse supernovae above 16-18
solar masses, (2) the identification of luminous-massive stars that quietly
disappear without optically bright supernovae, (3) the absence in the nebular
spectra of supernovae of type II-P of the nucleosynthetic products expected
from progenitors above 20 solar masses, (4) the absence in color magnitude
diagrams of stars in the environment of historic core-collapse supernovae of
stars with >20 solar masses. From the results in these different areas of
observational astrophysics, and the recently confirmed dependence of black hole
formation on metallicity and redshift of progenitors, it is concluded that a
large fraction of massive stellar binaries in the universe end as binary black
holes.


title:
Image Processing with Dipole-Coupled Nanomagnets: Noise Suppression and
  Edge Enhancement Detection

abstract:
  Hardware based image processing offers speed and convenience not found in
software-centric approaches. Here, we show theoretically that a two-dimensional
periodic array of dipole-coupled elliptical nanomagnets, delineated on a
piezoelectric substrate, can act as a dynamical system for specific image
processing functions. Each nanomagnet has two stable magnetization states that
encode pixel color (black or white). An image containing black and white pixels
is first converted to voltage states and then mapped into the magnetization
states of a nanomagnet array with magneto-tunneling junctions (MTJs). The same
MTJs are employed to read out the processed pixel colors later. Dipole
interaction between the nanomagnets implements specific image processing tasks
such as noise reduction and edge enhancement detection. These functions are
triggered by applying a global strain to the nanomagnets with a voltage dropped
across the piezoelectric substrate. An image containing an arbitrary number of
black and white pixels can be processed in few nanoseconds with very low energy
cost.


title: Black holes formed by direct collapse: observational evidences

abstract:
  Binary black holes as the recently detected sources of gravitational waves
can be formed from massive stellar binaries in the field or by dynamical
interactions in clusters of high stellar density, if the black holes are the
remnants of massive stars that collapsed without natal kicks that would disrupt
the binary system or eject the black holes from the cluster before binary black
hole formation. Here are summarized and discussed the kinematics in three
dimensions of space of five Galactic black hole X-ray binaries. For Cygnus X-1
and GRS 1915+105 it is found that the black holes of ~15 and ~10 solar masses
in these sources were formed in situ, without energetic kicks. These
observations suggest that binary black holes with components of ~10 solar
masses may have been prolifically produced in the universe.


title: On Cusp Solutions to a Prescribed Mean Curvature Equation

abstract:
  The nonexistence of "cusp solutions" of prescribed mean curvature boundary
value problems in $\Omega\times{\bf R}$ when $\Omega$ is a domain in ${\bf
R}^{2}$ is proven in certain cases and an application to radial limits at a
corner is mentioned.


title: MS MARCO: A Human Generated MAchine Reading COmprehension Dataset

abstract:
  We introduce a large scale MAchine Reading COmprehension dataset, which we
name MS MARCO. The dataset comprises of 1,010,916 anonymized
questions---sampled from Bing's search query logs---each with a human generated
answer and 182,669 completely human rewritten generated answers. In addition,
the dataset contains 8,841,823 passages---extracted from 3,563,535 web
documents retrieved by Bing---that provide the information necessary for
curating the natural language answers. A question in the MS MARCO dataset may
have multiple answers or no answers at all. Using this dataset, we propose
three different tasks with varying levels of difficulty: (i) predict if a
question is answerable given a set of context passages, and extract and
synthesize the answer as a human would (ii) generate a well-formed answer (if
possible) based on the context passages that can be understood with the
question and passage context, and finally (iii) rank a set of retrieved
passages given a question. The size of the dataset and the fact that the
questions are derived from real user search queries distinguishes MS MARCO from
other well-known publicly available datasets for machine reading comprehension
and question-answering. We believe that the scale and the real-world nature of
this dataset makes it attractive for benchmarking machine reading comprehension
and question-answering models.


title: Negative free carrier absorption in terahertz quantum cascade lasers

abstract:
  We analyze the peculiar case where the free carrier absorption arising from
LO phonon absorption-assisted transitions becomes negative and therefore turns
into a gain source for quantum cascade lasers. Such an additional source of
gain exists when the ratio between the electronic and the lattice temperatures
is larger than one, a condition that is usually fulfilled in quantum cascade
lasers. We find a gain of few cm$^{-1}$'s at 200K. We report the development of
a terahertz quantum cascade laser operating in the negative free carrier
absorption regime.


title: Promiscuously Quadratic Rings

abstract:
  We consider a convenient category of "quadratic" multirings, that allows
simple functorial relations with categories associated with abstract quadratic
forms theories and shares many good aspects of the theories of Special Groups
and of Realsemigroups, but tries to avoids its drawbacks.


title:
Klein's Paradox and the Relativistic $\delta$-shell Interaction in
  $\mathbb{R}^3$

abstract:
  Under certain hypothesis of smallness of the regular potential $\mathbf{V}$,
we prove that the Dirac operator in $\mathbb{R}^3$ coupled with a suitable
re-scaling of $\mathbf{V}$ converges in the strong resolvent sense to the
Hamiltonian coupled with a $\delta$-shell potential supported on $\Sigma$, a
bounded $C^2$ surface. Nevertheless, the coupling constant depends non-linearly
on the potential $\mathbf{V}$: the Klein's Paradox comes into play.


title:
Near-Infrared Emission Spectrum of WASP-103b using Hubble Space
  Telescope/Wide Field Camera 3

abstract:
  We present here our observations and analysis of the dayside emission
spectrum of the hot Jupiter WASP-103b. We observed WASP-103b during secondary
eclipse using two visits of the Hubble Space Telescope with the G141 grism on
Wide Field Camera 3 in spatial scan mode. We generated secondary eclipse light
curves of the planet in both blended white-light and spectrally binned
wavechannels from 1.1-1.7 micron and corrected the light curves for flux
contamination from a nearby companion star. We modeled the detector systematics
and secondary eclipse spectrum using Gaussian process regression and found that
the near-IR emission spectrum of WASP-103b is featureless across the observed
near-IR region to down to a sensitivity of 175 ppm, and shows a shallow slope
towards the red. The atmosphere has a single brightness temperature of T_B =
2890 K across this wavelength range. This region of the spectrum is
indistinguishable from isothermal, but may not manifest from a physically
isothermal system, i.e. pseudo-isothermal. A Solar-metallicity profile with a
thermal inversion layer at 10^-2 bar fits WASP-103b's spectrum with high
confidence, as do an isothermal profile with Solar metallicity and a
monotonically decreasing atmosphere with C/O>1. The data rule out a
monotonically decreasing atmospheric profile with Solar composition, and we
rule out a low-metallicity decreasing profile as non-physical for this system.
The pseudo-isothermal profile could be explained by a thermal inversion layer
just above the layer probed by our observations, or by clouds or haze in the
upper atmosphere. Transmission spectra at optical wavelengths would allow us to
better differentiate between potential atmospheric models.


title: On polytopes with congruent projections or sections

abstract:
  Let $2\le k\le d-1$ and let $P$ and $Q$ be two convex polytopes in ${\mathbb
E^d}$. Assume that their projections, $P|H$, $Q|H$, onto every $k$-dimensional
subspace $H$, are congruent. In this paper we show that $P$ and $Q$ or $P$ and
$-Q$ are translates of each other. We also prove an analogous result for
sections by showing that $P=Q$ or $P=-Q$, provided the polytopes contain the
origin in their interior and their sections, $P \cap H$, $Q \cap H$, by every
$k$-dimensional subspace $H$, are congruent.


title: Normalizer Circuits and Quantum Computation

abstract:
  (Abridged abstract.) In this thesis we introduce new models of quantum
computation to study the emergence of quantum speed-up in quantum computer
algorithms.
  Our first contribution is a formalism of restricted quantum operations, named
normalizer circuit formalism, based on algebraic extensions of the qubit
Clifford gates (CNOT, Hadamard and $\pi/4$-phase gates): a normalizer circuit
consists of quantum Fourier transforms (QFTs), automorphism gates and quadratic
phase gates associated to a set $G$, which is either an abelian group or
abelian hypergroup. Though Clifford circuits are efficiently classically
simulable, we show that normalizer circuit models encompass Shor's celebrated
factoring algorithm and the quantum algorithms for abelian Hidden Subgroup
Problems. We develop classical-simulation techniques to characterize under
which scenarios normalizer circuits provide quantum speed-ups. Finally, we
devise new quantum algorithms for finding hidden hyperstructures. The results
offer new insights into the source of quantum speed-ups for several algebraic
problems.
  Our second contribution is an algebraic (group- and hypergroup-theoretic)
framework for describing quantum many-body states and classically simulating
quantum circuits. Our framework extends Gottesman's Pauli Stabilizer Formalism
(PSF), wherein quantum states are written as joint eigenspaces of stabilizer
groups of commuting Pauli operators: while the PSF is valid for qubit/qudit
systems, our formalism can be applied to discrete- and continuous-variable
systems, hybrid settings, and anyonic systems. These results enlarge the known
families of quantum processes that can be efficiently classically simulated.
  This thesis also establishes a precise connection between Shor's quantum
algorithm and the stabilizer formalism, revealing a common mathematical
structure in several quantum speed-ups and error-correcting codes.


title: Light propagation through black-hole lattices

abstract:
  The apparent properties of distant objects encode information about the way
the light they emit propagates to an observer, and therefore about the
curvature of the underlying spacetime. Measuring the relationship between the
redshift $z$ and the luminosity distance $D_{\rm L}$ of a standard candle, for
example, yields information on the Universe's matter content. In practice,
however, in order to decode this information the observer needs to make an
assumption about the functional form of the $D_{\rm L}(z)$ relation; in other
words, a cosmological model needs to be assumed. In this work, we use
numerical-relativity simulations, equipped with a new ray-tracing module, to
numerically obtain this relation for a few black-hole--lattice cosmologies and
compare it to the well-known Friedmann-Lema\^itre-Robertson-Walker case, as
well as to other relevant cosmologies and to the Empty-Beam Approximation. We
find that the latter provides the best estimate of the luminosity distance and
formulate a simple argument to account for this agreement. We also find that a
Friedmann-Lema\^itre-Robertson-Walker model can reproduce this observable
exactly, as long as a time-dependent cosmological constant is included in the
fit. Finally, the dependence of these results on the lattice mass-to-spacing
ratio $\mu$ is discussed: we discover that, unlike the expansion rate, the
$D_{\rm L}(z)$ relation in a black-hole lattice does not tend to that measured
in the corresponding continuum spacetime as $\mu \to 0$.


title:
Rigorous effective bounds on the Hausdorff dimension of continued
  fraction Cantor sets: a hundred decimal digits for the dimension of $E_2$

abstract:
  We prove that the algorithm of [13] for approximating the Hausdorff dimension
of dynamically defined Cantor sets, using periodic points of the underlying
dynamical system, can be used to establish completely rigorous high accuracy
bounds on the dimension. The effectiveness of these rigorous estimates is
illustrated for Cantor sets consisting of continued fraction expansions with
restricted digits. For example the Hausdorff dimension of the set $E_2$ (of
those reals whose continued fraction expansion only contains digits 1 and 2)
can be rigorously approximated, with an accuracy of over 100 decimal places,
using points of period up to 25.
  The method for establishing rigorous dimension bounds involves the
holomorphic extension of mappings associated to the allowed continued fraction
digits, an appropriate disc which is contracted by these mappings, and an
associated transfer operator acting on the Hilbert Hardy space of analytic
functions on this disc. We introduce methods for rigorously bounding the
approximation numbers for the transfer operators, showing that this leads to
effective estimates on the Taylor coefficients of the associated determinant,
and hence to explicit bounds on the Hausdorff dimension.


title:
Nonlinear pseudo-differential equations defined by elliptic symbols on
  ${\lp}$ and the fractional Laplacian

abstract:
  We develop an $L^p(\mathbb{R}^n)$-functional calculus appropriated for
interpreting "non-classical symbols" of the form $a(-\Delta)$, and for proving
existence in $L^q(\mathbb{R}^n)$, some $q > p$, of solutions to nonlinear
pseudo-differential equations of the form $[1 + a(-\Delta)]^{s/2} (u) =
V(\cdot, u)$. More precisely, we use the theory of Fourier multipliers for
constructing suitable domains on which the formal operator appearing in the
above equation can be rigorously defined, and we prove existence of solutions
belonging to these domains. We also include applications of the theory to
equations of physical interest involving the fractional Laplace operator such
as the Allen-Cahn equation.


title:
Explicit Description of A Certain Destabilizing Wall of Skyscraper
  Sheaves on Ruled Surfaces

abstract:
  We give a explicit description of gluing stability conditions on ruled
surfaces by introducing gluing perversity. Moreover, we describe a
destabilizing wall of skyscraper sheaves on ruled surfaces by deformation of
stability conditions glued from $\widetilde{GL^{+}}(2,\mathbb{R})$-translates
of the standard stability condition on the base curve.


title: Dyck Paths and Positroids from Unit Interval Orders

abstract:
  It is well known that the number of non-isomorphic unit interval orders on
$[n]$ equals the $n$-th Catalan number. Using work of Skandera and Reed and
work of Postnikov, we show that each unit interval order on $[n]$ naturally
induces a rank $n$ positroid on $[2n]$. We call the positroids produced in this
fashion unit interval positroids. We characterize the unit interval positroids
by describing their associated decorated permutations, showing that each one
must be a $2n$-cycle encoding a Dyck path of length $2n$. We also provide
recipes to read the decorated permutation of a unit interval positroid $P$ from
both the antiadjacency matrix and the interval representation of the unit
interval order inducing $P$. Using our characterization of the decorated
permutation, we describe the Le-diagrams corresponding to unit interval
positroids. In addition, we give a necessary and sufficient condition for two
Grassmann cells parameterized by unit interval positroids to be adjacent inside
the Grassmann cell complex. Finally, we propose a potential approach to find
the $f$-vector of a unit interval order.


title: Alexander type invariants of tangles

abstract:
  We study generalizations of a classical link invariant -- the multivariable
Alexander polynomial -- to tangles. The starting point is Archibald's tMVA
invariant for virtual tangles which lives in the setting of circuit algebras,
and whose target space has dimension that is exponential in the number of
strands. Using the Hodge star map and restricting to tangles without closed
components, we define a reduction of the tMVA to an invariant "rMVA" which is
valued in matrices with Laurent polynomial entries, and so has a much more
compact target space. We show the rMVA has the structure of a metamonoid
morphism and is further equivalent to a tangle invariant defined by Bar-Natan.
This invariant also reduces to the Gassner representation on braids and has a
partially defined trace operation for closing open strands of a tangle.


title:
Irreducibility of the set of cubic polynomials with one periodic
  critical point

abstract:
  The space of monic centered cubic polynomials with marked critical points is
isomorphic to C^2. For each n>0, the locus Sn formed by all polynomials with a
specified critical point periodic of exact period n forms an affine algebraic
set. We prove that Sn is irreducible, thus giving an affirmative answer to a
question posed by Milnor. (This manuscript has been withdrawn)


title:
Cross sections of X-ray production induced by C and Si ions with
  energies up to 1 MeV/u on Ti, Fe, Zn, Nb, Ru and Ta

abstract:
  X-ray production differential cross sections induced by C and Si ions with
energies from 1 MeV/u down to 0.25 MeV/u, produced by the CMAM 5 MV tandem
accelerator, have been measured for thin targets of Ti, Fe, Zn, Nb, Ru and Ta
in a direct way. X-rays have been detected by a fully characterized silicon
drift diode and beam currents have been measured by a system of two Faraday
cups. Measured cross sections agree in general with previously published
results. The ECPSSR theory with the united atoms correction gives absolute
values close to the experimental ones for all the studied elements excited by C
ions and for Ta, Nb and Ru excited by Si ions. For Ti, Fe and Zn excited by Si,
the basic ECPSSR theory gives better agreement, although on absolute values the
gap for Ti is still large.


title: The spatial dynamics of ecosystem engineers

abstract:
  The changes on abiotic features of ecosystems have rarely been taken into
account by population dynamics models, which typically focus on trophic and
competitive interactions between species. However, understanding the population
dynamics of organisms that must modify their habitats in order to survive, the
so-called ecosystem engineers, requires the explicit incorporation of abiotic
interactions in the models. Here we study a model of ecosystem engineers that
is discrete both in space and time, and where the engineers and their habitats
are arranged in patches fixed to the sites of regular lattices. The growth of
the engineer population is modeled by Ricker equation with a density-dependent
carrying capacity that is given by the number of modified habitats. A diffusive
dispersal stage ensures that a fraction of the engineers move from their birth
patches to neighboring patches. We find that dispersal influences the
metapopulation dynamics only in the case that the local or single-patch
dynamics exhibits chaotic behavior. In that case, it can suppress the chaotic
behavior and avoid extinctions in the regime of large intrinsic growth rate of
the population.


title:
Electronic structure of BaSnO3 investigated by high-energy-resolution
  electron energy-loss spectroscopy and ab initio calculations

abstract:
  There has been growing interest in perovskite BaSnO3 due to its desirable
properties for oxide electronic devices including high electron mobility at
room temperature and optical transparency. As these electronic and optical
properties originate largely from the electronic structure of the material,
here the basic electronic structure of epitaxially-grown BaSnO3 films is
studied using high-energy-resolution electron energy-loss spectroscopy in a
transmission electron microscope and ab initio calculations. This study
provides a detailed description of the dielectric function of BaSnO3, including
the energies of bulk plasmon excitations and critical interband electronic
transitions, the band structure and partial densities of states, the measured
band gap, and more. To make the study representative of a variety of deposition
methods, results from BaSnO3 films grown by both hybrid molecular beam epitaxy
and high pressure oxygen sputter deposition are reported.


title:
Coherent transport properties of a three-terminal hybrid superconducting
  interferometer

abstract:
  We present an exhaustive theoretical analysis of a double-loop Josephson
proximity interferometer, as the one recently realized by Strambini et al. for
the control of the Andreev spectrum via an external magnetic field. This
system, called $\omega$-SQUIPT, consists of a T-shaped diffusive normal metal
(N) attached to three superconductors (S) forming a double loop configuration.
By using the quasiclassical Green function formalism, we calculate the local
normalized density of states, the Josephson currents through the device and the
dependence of the former on the length of the junction arms, the applied
magnetic field and the S/N interface transparencies. We show that by tuning the
fluxes through the double loop, the system undergoes transitions from a gapped
to a gapless state. We also evaluate the Josephson currents flowing in the
different arms as a function of magnetic fluxes and explore the quasi-particle
transport, by considering a metallic probe tunnel-coupled to the Josephson
junction and calculating its I-V characteristics. Finally, we study the
performances of the $\omega$-SQUIPT and its potential applications, by
investigating its electrical and magnetometric properties.


title: A Simple Hubbard Model for the Excited States of Dibenzoterrylene

abstract:
  We use a simple Hubbard model to characterize the electronic excited states
of the dibenzoterrylene (DBT) molecule; we compute the excited state transition
energies and oscillator strengths from the ground state to several singlet
excited states. We consider the lowest singlet and triplet states of the
molecule, examine their wavefunctions, and compute the density correlation
functions that describe these states. We find that the DBT ground state is
mostly a closed shell singlet with very slight radical character. We predict a
relatively small singlet-triplet splitting of 0.75 eV, which is less than the
mid-sized -acenes but larger than literature predictions for this state; this
is because the Hubbard interaction makes a very small correction to the singlet
and triplet states.


title:
A supercharacter theory for Sylow $p$-subgroups of the Steinberg
  triality groups

abstract:
  We determine a supercharacter theory for the matrix Sylow $p$-subgroup
${^3}D_4^{syl}(q^3)$ of the Steinberg triality group ${^3}D_4(q^3)$, and
establish the supercharacter table of ${^3}D_4^{syl}(q^3)$.


title:
Dense Prediction on Sequences with Time-Dilated Convolutions for Speech
  Recognition

abstract:
  In computer vision pixelwise dense prediction is the task of predicting a
label for each pixel in the image. Convolutional neural networks achieve good
performance on this task, while being computationally efficient. In this paper
we carry these ideas over to the problem of assigning a sequence of labels to a
set of speech frames, a task commonly known as framewise classification. We
show that dense prediction view of framewise classification offers several
advantages and insights, including computational efficiency and the ability to
apply batch normalization. When doing dense prediction we pay specific
attention to strided pooling in time and introduce an asymmetric dilated
convolution, called time-dilated convolution, that allows for efficient and
elegant implementation of pooling in time. We show results using time-dilated
convolutions in a very deep VGG-style CNN with batch normalization on the Hub5
Switchboard-2000 benchmark task. With a big n-gram language model, we achieve
7.7% WER which is the best single model single-pass performance reported so
far.


title: Thermodynamic competition between membrane protein oligomeric states

abstract:
  Self-assembly of protein monomers into distinct membrane protein oligomers
provides a general mechanism for diversity in the molecular architectures, and
resulting biological functions, of membrane proteins. We develop a general
physical framework describing the thermodynamic competition between different
oligomeric states of membrane proteins. Using the mechanosensitive channel of
large conductance as a model system, we show how the dominant oligomeric states
of membrane proteins emerge from the interplay of protein concentration in the
cell membrane, protein-induced lipid bilayer deformations, and direct
monomer-monomer interactions. Our results suggest general physical mechanisms
and principles underlying regulation of protein function via control of
membrane protein oligomeric state.

categories: q-bio.BM cond-mat.soft physics.bio-ph q-bio.SC


title:
Analogue model for anti-de Sitter as a description of point sources in
  fluids

abstract:
  We introduce an analogue model for a nonglobally hyperbolic spacetime in
terms of a two-dimensional fluid. This is done by considering the propagation
of sound waves in a radial flow with constant velocity. We show that the
equation of motion satisfied by sound waves is the wave equation on
$AdS_2\times S^1$. Since this spacetime is not globally hyperbolic, the
dynamics of the Klein-Gordon field is not well defined until boundary
conditions at the spatial boundary of $AdS_2$ are prescribed. On the analogue
model end, those extra boundary conditions provide an effective description of
the point source at $r=0$. For waves with circular symmetry, we relate the
different physical evolutions to the phase difference between ingoing and
outgoing scattered waves. We also show that the fluid configuration can be
stable or unstable depending on the chosen boundary condition.


title: Trees with distinguishing number two

abstract:
  The distinguishing number $D(G)$ of a graph $G$ is the least integer $d$ such
that $G$ has a vertex labeling with $d$ labels that is preserved only by a
trivial automorphism. In this paper we characterize all trees with radius at
most three and distinguishing number two. Also we present a necessary condition
for trees with distinguishing number two and radius more than three.


title:
On classification of higher-order integrable nonlinear partial
  differential equations

abstract:
  We investigate existence of solitonic solutions for higher-order partial
differential equations with polynomial nonlinearities. Using the Hirota method
we obtain classification for higher-order integrable systems of equations.


title:
Bayesian Parameter Estimation via Filtering and Functional
  Approximations

abstract:
  The inverse problem of determining parameters in a model by comparing some
output of the model with observations is addressed. This is a description for
what hat to be done to use the Gauss-Markov-Kalman filter for the Bayesian
estimation and updating of parameters in a computational model. This is a
filter acting on random variables, and while its Monte Carlo variant --- the
Ensemble Kalman Filter (EnKF) --- is fairly straightforward, we subsequently
only sketch its implementation with the help of functional representations.


title:
A Variation on the Donsker-Varadhan Inequality for the Principial
  Eigenvalue

abstract:
  The purpose of this short note is to give a variation on the classical
Donsker-Varadhan inequality, which bounds the first eigenvalue of a
second-order elliptic operator on a bounded domain $\Omega$ by the largest mean
first exit time of the associated drift-diffusion process via $$\lambda_1 \geq
\frac{1}{\sup_{x \in \Omega} \mathbb{E}_x \tau_{\Omega^c}}.$$ Instead of
looking at the mean of the first exit time, we study quantiles: let $d_{p,
\partial \Omega}:\Omega \rightarrow \mathbb{R}_{\geq 0}$ be the smallest time
$t$ such that the likelihood of exiting within that time is $p$, then
$$\lambda_1 \geq \frac{\log{(1/p)}}{\sup_{x \in \Omega} d_{p,\partial
\Omega}(x)}.$$ Moreover, as $p \rightarrow 0$, this lower bound converges to
$\lambda_1$.


title: Linearized Holographic Isotropization at Finite Coupling

abstract:
  We study holographic isotropization of an anisotropic homogeneous non-Abelian
strongly coupled plasma in the presence of Gauss-Bonnet corrections. It was
verified before that one can linearize Einstein's equations around the final
black hole background and simplify the complicated setup. Using this approach,
we study the expectation value of the boundary stress tensor. Although we
consider small values of the Gauss-Bonnet coupling constant, it is found that
finite coupling leads to significant increasing of the thermalization time. By
including higher order corrections in linearization, we extend the results to
study the effect of the Gauss-Bonnet coupling on the entropy production on the
event horizon.


title: Congestion-Free Rerouting of Flows on DAGs

abstract:
  Changing a given configuration in a graph into another one is known as a re-
configuration problem. Such problems have recently received much interest in
the context of algorithmic graph theory. We initiate the theoretical study of
the following reconfiguration problem: How to reroute $k$ unsplittable flows of
a certain demand in a capacitated network from their current paths to their
respective new paths, in a congestion-free manner? This problem finds immediate
applications, e.g., in traffic engineering in computer networks. We show that
the problem is generally NP-hard already for $k = 2$ flows, which motivates us
to study rerouting on a most basic class of flow graphs, namely DAGs.
Interestingly, we find that for general $k$, deciding whether an unsplittable
multi-commodity flow rerouting schedule exists, is NP-hard even on DAGs. Both
NP-hardness proofs are non-trivial. Our main contribution is a polynomial-time
(fixed parameter tractable) algorithm to solve the route update problem for a
bounded number of flows on DAGs. At the heart of our algorithm lies a novel
decomposition of the flow network that allows us to express and resolve
reconfiguration dependencies among flows.


title: A New Class of Maximal Triangular Aglebras

abstract:
  Triangular algebras, and maximal triangular algebras in particular, have been
objects of interest for over fifty years. Rich families of examples have been
studied in the context of many w$^*$- and C$^*$-algebras, but there remains a
dearth of concrete examples in B(H). In previous work, we described a family of
maximal triangular algebras of finite multiplicity. Here, we investigate a
related family of maximal triangular algebras with infinite multiplicity, and
unearth new asymptotic structure which these algebras exhibit.


title: Length-dependent thermopower of single-molecule junctions

abstract:
  In the present work we theoretically study the length dependence of
thermopower of a single-molecule junction with a chain-like molecular bridge of
an arbitrary length using a tight-binding model. We analyze conditions bringing
a nonlinear growth of the thermopower accompanying the extension of the bridge
length. Also, we show that the thermopower may decrease with increasing
molecular length provided that the molecular bridge is sufficiently long.


title:
Reply to "Comment on `Gleason-type theorem including qubits and
  projective measurements: the Born rule beyond quantum physics' ", by Michael
  J. W. Hall

abstract:
  We present a reply to the objections raised by M. J. W. Hall against our
extension of Gleason's theorem.


title: Asymptotic approximation of optimal portfolio for small time horizons

abstract:
  We consider the problem of portfolio optimization in a simple incomplete
market and under a general utility function. By working with the associated
Hamilton-Jacobi-Bellman partial differential equation (HJB PDE), we obtain a
closed-form formula for a trading strategy which approximates the optimal
trading strategy when the time horizon is small. This strategy is generated by
a first order approximation to the value function. The approximate value
function is obtained by constructing classical sub- and super-solutions to the
HJB PDE using a formal expansion in powers of horizon time. Martingale
inequalities are used to sandwich the true value function between the
constructed sub- and super-solutions. A rigorous proof of the accuracy of the
approximation formulas is given. We end with a heuristic scheme for extending
our small-time approximating formulas to approximating formulas in a finite
time horizon.


title:
Efficient variational quantum simulator incorporating active error
  minimisation

abstract:
  One of the key applications for quantum computers will be the simulation of
other quantum systems that arise in chemistry, materials science, etc, in order
to accelerate the process of discovery. It is important to ask: Can this be
achieved using near future quantum processors, of modest size and under
imperfect control, or must it await the more distant era of large-scale
fault-tolerant quantum computing? Here we propose a variational method
involving closely integrated classical and quantum coprocessors. We presume
that all operations in the quantum coprocessor are prone to error. The impact
of such errors is minimised by boosting them artificially and then
extrapolating to the zero-error case. In comparison to a more conventional
optimised Trotterisation technique, we find that our protocol is efficient and
appears to be fundamentally more robust against error accumulation.


title:
High-frequency Oscillations in Small Magnetic Elements Observed with
  Sunrise/SuFI

abstract:
  We characterize waves in small magnetic elements and investigate their
propagation in the lower solar atmosphere from observations at high spatial and
temporal resolution. We use the wavelet transform to analyze oscillations of
both horizontal displacement and intensity in magnetic bright points found in
the 300 nm and the Ca II H 396.8 nm passbands of the filter imager on board the
Sunrise balloon-borne solar observatory. Phase differences between the
oscillations at the two atmospheric layers corresponding to the two passbands
reveal upward propagating waves at high frequencies (up to 30 mHz). Weak
signatures of standing as well as downward propagating waves are also obtained.
Both compressible and incompressible (kink) waves are found in the small-scale
magnetic features. The two types of waves have different, though overlapping,
period distributions. Two independent estimates give a height difference of
approximately 450+-100 km between the two atmospheric layers sampled by the
employed spectral bands. This value, together with the determined short travel
times of the transverse and longitudinal waves provide us with phase speeds of
29+-2 km/s and 31+-2 km/s, respectively. We speculate that these phase speeds
may not reflect the true propagation speeds of the waves. Thus, effects such as
the refraction of fast longitudinal waves may contribute to an overestimate of
the phase speed.


title:
Phenomenological analysis of associated production of $Z^0+b$ in the $b
  \rightarrow J/\psi X$ decay channel at the LHC

abstract:
  The ATLAS collaboration recently reported on the first observation of
associated-production of a $Z^0$ boson with a $J/\psi$. We recently claimed
that the corresponding yield of the {\it prompt} $J/\psi$ was dominated by
double parton scatterings in the ATLAS acceptance with a somewhat small value
of $\sigma_{\rm eff}$. We also found out that single parton scatterings were
only dominant at large transverse momenta. We present here the first
phenomenological analysis of another part of the ATLAS data sample, namely of a
$Z^0$ boson plus a {\it non-prompt} $J/\psi$. Our study is performed at
next-to-leading order in $\alpha_s$ and includes parton-shower effects via the
{\sc\small MadGraph5_aMC@NLO} framework. We find out that the data, unlike the
case of prompt $J/\psi+Z^0$, do not hint at significant DPS contributions.
Owing to the current experimental and theoretical uncertainties, there is still
a room for these but with a lower limit of $\sigma_{\rm eff}$ close to 5 mb. We
stress the importance of QCD corrections to account for the ATLAS data.


title:
Minimizing Multimodular Functions and Allocating Capacity in
  Bike-Sharing Systems

abstract:
  The growing popularity of bike-sharing systems around the world has motivated
recent attention to models and algorithms for their effective operation. Most
of this literature focuses on their daily operation for managing asymmetric
demand. In this work, we consider the more strategic question of how to
(re-)allocate dock-capacity in such systems. We develop mathematical
formulations for variations of this problem (either for service performance
over the course of one day or for a long-run-average) and exhibit discrete
convex properties in associated optimization problems. This allows us to design
a practically fast polynomial-time allocation algorithm to compute an optimal
solution for this problem, which can also handle practically motivated
constraints, such as a limit on the number of docks moved in the system.
  We apply our algorithm to data sets from Boston, New York City, and Chicago
to investigate how different dock allocations can yield better service in these
systems. Recommendations based on our analysis have led to changes in the
system design in Chicago and New York City. Beyond optimizing for improved
quality of service through better allocations, our results also provide a
metric to compare the impact of strategically reallocating docks and the
rebalancing of bikes.


title: Numerical Study of Pseudo-gap Anisotropy for a Tight Binding Band

abstract:
  The Fermi surface anisotropy of a pseudo-gap in the spectral weight, caused
by superconducting fluctuations or anti-ferromagnetic fluctuations, is
calculated for a tight binding band. The importance of the Fermi surface saddle
point, or hot spot, is illustrated. A peak-dip-hump structure due to a finite
frequency mode, is briefly explored. The connection to high temperature
superconducting copper-oxides is discussed.


title:
Cavity Born-Oppenheimer Approximation for Correlated
  Electron-Nuclear-Photon Systems

abstract:
  In this work, we illustrate the recently introduced concept of the cavity
Born-Oppenheimer approximation for correlated electron-nuclear-photon problems
in detail. We demonstrate how an expansion in terms of conditional electronic
and photon-nuclear wave functions accurately describes eigenstates of strongly
correlated light-matter systems. For a GaAs quantum ring model in resonance
with a photon mode we highlight how the ground-state electronic
potential-energy surface changes the usual harmonic potential of the free
photon mode to a dressed mode with a double-well structure. This change is
accompanied by a splitting of the electronic ground-state density. For a model
where the photon mode is in resonance with a vibrational transition, we observe
in the excited-state electronic potential-energy surface a splitting from a
single minimum to a double minimum. Furthermore, for a time-dependent setup, we
show how the dynamics in correlated light-matter systems can be understood in
terms of population transfer between potential energy surfaces. This work at
the interface of quantum chemistry and quantum optics paves the way for the
full ab-initio description of matter-photon systems.


title:
Synthesis of low-moment CrVTiAl: a potential room temperature spin
  filter

abstract:
  The efficient production of spin-polarized currents at room temperature is
fundamental to the advancement of spintronics. Spin-filter materials ---
semiconductors with unequal band gaps for each spin channel --- can generate
spin-polarized current without the need for spin-polarized contacts. In
addition, a spin-filter material with zero magnetic moment would have the
advantage of not producing strong fringing fields that would interfere with
neighboring electronic components and limit the volume density of devices. The
quaternary Heusler compound CrVTiAl has been predicted to be a zero-moment
spin-filter material with a Curie temperature in excess of 1000 K. In this
work, CrVTiAl has been synthesized with a lattice constant of $a = 6.15 \AA$.
Magnetization measurements reveal an exceptionally low moment of $\mu = 2.3
\times 10^{-3} \mu_B/f.u.$ at a field of $\mu_0 H = 2 T$, that is independent
of temperature between T = 10 K and 400 K, consistent with the predicted
zero-moment ferrimagnetism. Transport measurements reveal a combination of
metallic and semiconducting components to the resistivity. Combining a
zero-moment spin-filter material with nonmagnetic electrodes would lead to an
essentially nonmagnetic spin injector. These results suggest that CrVTiAl is a
promising candidate for further research in the field of spintronics.


title:
Phenomenology of on-shell Higgs production in the MSSM with complex
  parameters

abstract:
  A computation of inclusive cross sections for neutral Higgs boson production
through gluon fusion and bottom-quark annihilation is presented in the MSSM
with complex parameters. The predictions for the gluon-fusion process are based
on an explicit calculation of the leading-order cross section for arbitrary
complex parameters which is supplemented by higher-order corrections: massive
top- and bottom-quark contributions at NLO QCD, in the heavy top-quark
effective theory the top-quark contribution up to N$^3$LO QCD including a soft
expansion for the $\mathcal{CP}$-even component of the light Higgs boson. For
its $\mathcal{CP}$-odd component and the heavy Higgs bosons the contributions
are incorporated up to NNLO QCD. Two-loop electroweak effects are also
incorporated, and SUSY QCD corrections at NLO are interpolated from the MSSM
with real parameters. Finite wave function normalisation factors ensuring
correct on-shell properties of the external Higgs bosons are incorporated from
the code $\texttt{FeynHiggs}$. For the typical case of a strong admixture of
the two heavy Higgs bosons it is demonstrated that squark effects are strongly
dependent on the phases of the complex parameters. The remaining theoretical
uncertainties for cross sections are discussed. The results have been
implemented into an extension of the numerical code $\texttt{SusHi}$ called
$\texttt{SusHiMi}$.


title: Gaze Embeddings for Zero-Shot Image Classification

abstract:
  Zero-shot image classification using auxiliary information, such as
attributes describing discriminative object properties, requires time-consuming
annotation by domain experts. We instead propose a method that relies on human
gaze as auxiliary information, exploiting that even non-expert users have a
natural ability to judge class membership. We present a data collection
paradigm that involves a discrimination task to increase the information
content obtained from gaze data. Our method extracts discriminative descriptors
from the data and learns a compatibility function between image and gaze using
three novel gaze embeddings: Gaze Histograms (GH), Gaze Features with Grid
(GFG) and Gaze Features with Sequence (GFS). We introduce two new
gaze-annotated datasets for fine-grained image classification and show that
human gaze data is indeed class discriminative, provides a competitive
alternative to expert-annotated attributes, and outperforms other baselines for
zero-shot image classification.


title: Currents and Radiation from the large $D$ Black Hole Membrane

abstract:
  It has recently been demonstrated that black hole dynamics in a large number
of dimensions $D$ reduces to the dynamics of a codimension one membrane
propagating in flat space. In this paper we define a stress tensor and charge
current on this membrane and explicitly determine these currents at low orders
in the expansion in $\frac{1}{D}$. We demonstrate that dynamical membrane
equations of motion derived in earlier work are simply conservation equations
for our stress tensor and charge current. Through the paper we focus on
solutions of the membrane equations which vary on a time scale of order unity.
Even though the charge current and stress tensor are not parametrically small
in such solutions, we show that the radiation sourced by the corresponding
membrane currents is generically of order $\frac{1}{D^D}$. In this regime it
follows that the `near horizon' membrane degrees of freedom are decoupled from
asymptotic flat space at every perturbative order in the $\frac{1}{D}$
expansion. We also define an entropy current on the membrane and use the
Hawking area theorem to demonstrate that the divergence of the entropy current
is point wise non negative. We view this result as a local form of the second
law of thermodynamics for membrane motion.


title:
Nonlocal energy density functionals for pairing and beyond-mean-field
  calculations

abstract:
  We propose to use two-body regularized finite-range pseudopotential to
generate nuclear energy density functional (EDF) in both particle-hole and
particle-particle channels, which makes it free from self-interaction and
self-pairing, and also free from singularities when used beyond mean field. We
derive a sequence of pseudopotentials regularized up to next-to-leading order
(NLO) and next-to-next-to-leading order (N2LO), which fairly well describe
infinite-nuclear-matter properties and finite open-shell paired and/or deformed
nuclei. Since pure two-body pseudopotentials cannot generate sufficiently large
effective mass, the obtained solutions constitute a preliminary step towards
future implementations, which will include, e.g., EDF terms generated by
three-body pseudopotentials.


title: Hierarchical Boundary-Aware Neural Encoder for Video Captioning

abstract:
  The use of Recurrent Neural Networks for video captioning has recently gained
a lot of attention, since they can be used both to encode the input video and
to generate the corresponding description. In this paper, we present a
recurrent video encoding scheme which can discover and leverage the
hierarchical structure of the video. Unlike the classical encoder-decoder
approach, in which a video is encoded continuously by a recurrent layer, we
propose a novel LSTM cell, which can identify discontinuity points between
frames or segments and modify the temporal connections of the encoding layer
accordingly. We evaluate our approach on three large-scale datasets: the
Montreal Video Annotation dataset, the MPII Movie Description dataset and the
Microsoft Video Description Corpus. Experiments show that our approach can
discover appropriate hierarchical representations of input videos and improve
the state of the art results on movie description datasets.


title:
Chromospheric and Coronal Activity in the 500-Myr-old Open Cluster M37:
  Evidence for Coronal Stripping?

abstract:
  We present the results of a spectroscopic survey to characterize
chromospheric activity, as measured by H$\alpha$ emission, in low-mass members
of the 500-Myr-old open cluster M37. Combining our new measurements of
H$\alpha$ luminosities ($L_{H\alpha}$) with previously cataloged stellar
properties, we identify saturated and unsaturated regimes in the dependence of
the $L_{H\alpha}$-to-bolometric-luminosity ratio, $L_{H\alpha}/L_{bol}$, on the
Rossby number $R_o$. All rotators with Ro smaller than 0.03$\pm$0.01 converge
to an activity level of $L_{H\alpha}/L_{bol}$ = (1.27$\pm$0.02) x 10$^{-4}$.
This saturation threshold ($R_{o,sat}$ = 0.03$\pm$0.01) is statistically
smaller than that found in most studies of the rotation-activity relation. In
the unsaturated regime, slower rotators have lower levels of chromospheric
activity, with $L_{H\alpha}/L_{bol}$($R_o$) following a power-law of index
$\beta$ = -0.51$\pm$0.02, slightly shallower than the one found for a combined
$\approx$650-Myr-old sample of Hyades and Praesepe stars. By comparing this
unsaturated behavior to that previously found for coronal activity in M37 (as
measured via the X-ray luminosity, $L_X$), we confirm that chromospheric
activity decays at a much slower rate than coronal activity with increasing
$R_o$. While a comparison of $L_{H\alpha}$ and $L_X$ for M37 members with
measurements of both reveals a nearly 1:1 relation, removing the
mass-dependencies by comparing instead $L_{H\alpha}/L_{bol}$ and $L_X/L_{bol}$
does not provide clear evidence for such a relation. Finally, we find that
$R_{o,sat}$ is smaller for our chromospheric than for our coronal indicator of
activity ($R_{o,sat}$ = 0.03$\pm$0.01 versus 0.09$\pm$0.01). We interpret this
as possible evidence for coronal stripping.


title: Hybrid Bloch Brane

abstract:
  This work reports on models described by two real scalar fields coupled with
gravity in the five-dimensional spacetime, with a warped geometry involving one
infinite extra dimension. Through a mechanism that smoothly changes a thick
brane into a hybrid brane, one investigates the appearance of hybrid branes
hosting internal structure, characterized by the splitting on the energy
density and the volcano potential, induced by the parameter which controls
interactions between the two scalar fields. In particular, we investigate
distinct symmetric and asymmetric hybrid brane scenarios.


title: Oddness of residually reducible Galois representations

abstract:
  We show that suitable congruences between polarized automorphic forms over a
CM field always produce elements in the Selmer group for exactly the +/--Asai
(aka tensor induction) representation that is critical in the sense of Deligne.
For this we relate the oddness of the associated polarized Galois
representations (in the sense of the Bella\"iche-Chenevier sign being +1) to
the parity condition for criticality. Under an assumption similar to Vandiver's
conjecture this also provides evidence for the Fontaine-Mazur conjecture for
polarized Galois representations of any even dimension.


title: Forward Backward Similarity Search in Knowledge Networks

abstract:
  Similarity search is a fundamental problem in social and knowledge networks
like GitHub, DBLP, Wikipedia, etc. Existing network similarity measures are
limited because they only consider similarity from the perspective of the query
node. However, due to the complicated topology of real-world networks, ignoring
the preferences of target nodes often results in odd or unintuitive
performance. In this work, we propose a dual perspective similarity metric
called Forward Backward Similarity (FBS) that efficiently computes topological
similarity from the perspective of both the query node and the perspective of
candidate nodes. The effectiveness of our method is evaluated by traditional
quantitative ranking metrics and large-scale human judgement on four large real
world networks. The proposed method matches human preference and outperforms
other similarity search algorithms on community overlap and link prediction.
Finally, we demonstrate top-5 rankings for five famous researchers on an
academic collaboration network to illustrate how our approach captures
semantics more intuitively than other approaches.


title: Locality-Sensitive Hashing without False Negatives for l_p

abstract:
  In this paper, we show a construction of locality-sensitive hash functions
without false negatives, i.e., which ensure collision for every pair of points
within a given radius $R$ in $d$ dimensional space equipped with $l_p$ norm
when $p \in [1,\infty]$. Furthermore, we show how to use these hash functions
to solve the $c$-approximate nearest neighbor search problem without false
negatives. Namely, if there is a point at distance $R$, we will certainly
report it and points at distance greater than $cR$ will not be reported for
$c=\Omega(\sqrt{d},d^{1-\frac{1}{p}})$. The constructed algorithms work: - with
preprocessing time $\mathcal{O}(n \log(n))$ and sublinear expected query time,
- with preprocessing time $\mathcal{O}(\mathrm{poly}(n))$ and expected query
time $\mathcal{O}(\log(n))$. Our paper reports progress on answering the open
problem presented by Pagh [8] who considered the nearest neighbor search
without false negatives for the Hamming distance.


title: Dynamic Reductions for Model Checking Concurrent Software

abstract:
  Symbolic model checking of parallel programs stands and falls with effective
methods of dealing with the explosion of interleavings. We propose a dynamic
reduction technique to avoid unnecessary interleavings. By extending Lipton's
original work with a notion of bisimilarity, we accommodate dynamic
transactions, and thereby reduce dependence on the accuracy of static analysis,
which is a severe bottleneck in other reduction techniques.
  The combination of symbolic model checking and dynamic reduction techniques
has proven to be challenging in the past. Our generic reduction theorem
nonetheless enables us to derive an efficient symbolic encoding, which we
implemented for IC3 and BMC. The experiments demonstrate the power of dynamic
reduction on several case studies and a large set of SVCOMP benchmarks.


title:
Untangling the Near-IR Spectral Features in the Protoplanetary
  Environment of KH 15D

abstract:
  We report on Gemini/GNIRS observations of the binary T Tauri system V582 Mon
(KH 15D) at three orbital phases. These spectra allow us to untangle five
components of the system: the photosphere and magnetosphere of star B, the jet,
scattering properties of the ring material, and excess near-IR radiation
previously attributed to a possible self-luminous planet. We confirm an early-K
subgiant classification for star B and show that the magnetospheric He I
emission line is variable, possibly indicating increased mass accretion at
certain times. As expected, the H$_2$ emission features associated with the
inner part of the jet show no variation with orbital phase. We show that the
reflectance spectrum for the scattered light has a distinctive blue slope and
spectral features consistent with scattering and absorption by a mixture of
water and methane ice grains in the 1-50 $\mu$m size range. This suggests that
the methane frost line is closer than $\sim$5 AU in this system, requiring that
the grains be shielded from direct radiation. After correcting for features
from the scattered light, jet, magnetosphere, and photosphere, we confirm the
presence of leftover near-IR light from an additional source, detectable near
minimum brightness. A spectral emission feature matching the model spectrum of
a 10 M$_{J}$, 1 Myr old planet is found in the excess flux, but other expected
features from this model are not seen. Our observations, therefore, tentatively
support the picture that a luminous planet is present within the system,
although they cannot yet be considered definitive.


title:
Constraining the monochromatic gamma-rays from dark matter annihilation
  by the LHC

abstract:
  The installation of forward detectors in CMS and ATLAS turn the LHC to an
effective photon-photon collider. The elastic scattering of the beam-protons
via the emission of photons, which can be identified by tagging the intact
protons in the forward detectors, provides a powerful diagnostic of the central
production of new particles through photon-photon annihilation. In this letter
we study the central production of dark matter particles and the potential of
LHC to constrain the cross section of this process. By virtue of the crossing
symmetry, this limit can immediately be used to constrain the production of
monochromatic gamma-rays in dark matter annihilation, a smoking gun signal
under investigation in indirect dark matter searches. We show that with the
integrated luminosity $\mathcal{L}=30~{\rm fb}^{-1}$ in LHC at center-of-mass
energy $\sqrt{s}=$ 13 TeV, for dark matter masses $\sim (50-600)$ GeV, a
model-independent constraint on the cross section of dark matter annihilation
to monochromatic gamma-rays at the same order of magnitude as the current
Fermi-LAT and the future limits from CTA, can be obtained.


title: Improving Policy Gradient by Exploring Under-appreciated Rewards

abstract:
  This paper presents a novel form of policy gradient for model-free
reinforcement learning (RL) with improved exploration properties. Current
policy-based methods use entropy regularization to encourage undirected
exploration of the reward landscape, which is ineffective in high dimensional
spaces with sparse rewards. We propose a more directed exploration strategy
that promotes exploration of under-appreciated reward regions. An action
sequence is considered under-appreciated if its log-probability under the
current policy under-estimates its resulting reward. The proposed exploration
strategy is easy to implement, requiring small modifications to an
implementation of the REINFORCE algorithm. We evaluate the approach on a set of
algorithmic tasks that have long challenged RL methods. Our approach reduces
hyper-parameter sensitivity and demonstrates significant improvements over
baseline methods. Our algorithm successfully solves a benchmark multi-digit
addition task and generalizes to long sequences. This is, to our knowledge, the
first time that a pure RL method has solved addition using only reward
feedback.


title:
Rapid Sampling of Stochastic Displacements in Brownian Dynamics
  Simulations

abstract:
  We present a new method for sampling stochastic displacements in Brownian
Dynamics (BD) simulations of colloidal scale particles. The method relies on a
new formulation for Ewald summation of the Rotne-Prager-Yamakawa (RPY) tensor,
which guarantees that the real-space and wave-space contributions to the tensor
are independently symmetric and positive-definite for all possible particle
configurations. Brownian displacements are drawn from a superposition of two
independent samples: a wave-space (far-field or long-ranged) contribution,
computed using techniques from fluctuating hydrodynamics and non-uniform Fast
Fourier Transforms; and a real-space (near-field or short-ranged) correction,
computed using a Krylov subspace method. The combined computational complexity
of drawing these two independent samples scales linearly with the number of
particles. The proposed method circumvents the super-linear scaling exhibited
by all known iterative sampling methods applied directly to the RPY tensor that
results from the power law growth of the condition number of tensor with the
number of particles. Calculations for hard sphere dispersions and colloidal
gels are illustrated and used to explore the role of microstructure on
performance of the algorithm. In practice, the logarithmic part of the
predicted scaling is not observed and the algorithm scales linearly for up to 4
million particles, obtaining speed ups of over an order of magnitude over
existing iterative methods, and making the cost of computing Brownian
displacements comparable the cost of computing deterministic displacements in
BD simulations. A high-performance implementation employing non-uniform fast
Fourier transforms implemented on graphics processing units and integrated with
the software package HOOMD-blue is used for benchmarking.


title: Hyperlogarithms and periods in Feynman amplitudes

abstract:
  The role of hyperlogarithms and multiple zeta values (and their
generalizations) in Feynman amplitudes is being gradually recognized since the
mid 1990's. The present lecture provides a concise introduction to a fast
developing subject that attracts the interests of a wide range of specialists -
from number theorists to particle physicists.


title: A short remark on a Growth Fragmentation equation

abstract:
  An explicit solution for a growth fragmentation equation with constant
dislocation measure is obtained. In this example the necessary condition for
the general results in \cite{BW} about the existence of global solutions in the
so called self similar case is not satisfied. The solution is local and blows
up in finite time.


title: What Is Around The Camera?

abstract:
  How much does a single image reveal about the environment it was taken in? In
this paper, we investigate how much of that information can be retrieved from a
foreground object, combined with the background (i.e. the visible part of the
environment). Assuming it is not perfectly diffuse, the foreground object acts
as a complexly shaped and far-from-perfect mirror. An additional challenge is
that its appearance confounds the light coming from the environment with the
unknown materials it is made of. We propose a learning-based approach to
predict the environment from multiple reflectance maps that are computed from
approximate surface normals. The proposed method allows us to jointly model the
statistics of environments and material properties. We train our system from
synthesized training data, but demonstrate its applicability to real-world
data. Interestingly, our analysis shows that the information obtained from
objects made out of multiple materials often is complementary and leads to
better performance.


title:
The One Hundred Layers Tiramisu: Fully Convolutional DenseNets for
  Semantic Segmentation

abstract:
  State-of-the-art approaches for semantic image segmentation are built on
Convolutional Neural Networks (CNNs). The typical segmentation architecture is
composed of (a) a downsampling path responsible for extracting coarse semantic
features, followed by (b) an upsampling path trained to recover the input image
resolution at the output of the model and, optionally, (c) a post-processing
module (e.g. Conditional Random Fields) to refine the model predictions.
  Recently, a new CNN architecture, Densely Connected Convolutional Networks
(DenseNets), has shown excellent results on image classification tasks. The
idea of DenseNets is based on the observation that if each layer is directly
connected to every other layer in a feed-forward fashion then the network will
be more accurate and easier to train.
  In this paper, we extend DenseNets to deal with the problem of semantic
segmentation. We achieve state-of-the-art results on urban scene benchmark
datasets such as CamVid and Gatech, without any further post-processing module
nor pretraining. Moreover, due to smart construction of the model, our approach
has much less parameters than currently published best entries for these
datasets.
  Code to reproduce the experiments is available here :
https://github.com/SimJeg/FC-DenseNet/blob/master/train.py


title: The Grothendieck ring of varieties and algebraic K-theory of spaces

abstract:
  Waldhausen's algebraic K-theory machinery is applied to motivic homotopy
theory, producing an interesting motivic homotopy type. Over a field F of
characteristic zero, its path components receive a surjective ring homomorphism
from the Grothendieck ring of varieties over F.


title: Accelerated Gradient Temporal Difference Learning

abstract:
  The family of temporal difference (TD) methods span a spectrum from
computationally frugal linear methods like TD({\lambda}) to data efficient
least squares methods. Least square methods make the best use of available data
directly computing the TD solution and thus do not require tuning a typically
highly sensitive learning rate parameter, but require quadratic computation and
storage. Recent algorithmic developments have yielded several sub-quadratic
methods that use an approximation to the least squares TD solution, but incur
bias. In this paper, we propose a new family of accelerated gradient TD (ATD)
methods that (1) provide similar data efficiency benefits to least-squares
methods, at a fraction of the computation and storage (2) significantly reduce
parameter sensitivity compared to linear TD methods, and (3) are asymptotically
unbiased. We illustrate these claims with a proof of convergence in expectation
and experiments on several benchmark domains and a large-scale industrial
energy allocation domain.


title:
Accelerated front propagation for monostable equations with nonlocal
  diffusion: Multidimensional case

abstract:
  We describe acceleration of the front propagation for solutions to a class of
monostable nonlinear equations with a nonlocal diffusion in $\mathbb{R}^d$,
$d\geq1$. We show that the acceleration takes place if either the diffusion
kernel or the initial condition has 'regular' heavy tails in $\mathbb{R}^d$ (in
particular, decays slower than exponentially). Under general assumptions which
can be verified for particular models, we present sharp estimates for the
time-space zone which separates the region of convergence to the unstable zero
solution with the region of convergence to the stable positive constant
solution. We show the variety of different possible rates of the propagation
starting from a little bit faster than a linear one up to the exponential rate.
The paper generalizes to the case $d>1$ our results for the case $d=1$ obtained
early in https://dx.doi.org/10.1080/00036811.2017.1400537 .


title: The Spectrum of Static Subtracted Geometries

abstract:
  Subtracted geometries are black hole solutions of the four dimensional STU
model with rather interesting ties to asymptotically flat black holes. A
peculiar feature is that the solutions to the Klein-Gordon equation on this
subtracted background can be organized according to representations of the
conformal group $SO(2,2)$. We test if this behavior persists for the linearized
fluctuations of gravitational and matter fields on static, electrically charged
backgrounds of this kind. We find that there is a subsector of the modes that
do display conformal symmetry, while some modes do not. We also discuss two
different effective actions that describe these subtracted geometries and how
the spectrum of quasinormal modes is dramatically different depending upon the
action used.


title: Characterizing circles by a convex combinatorial property

abstract:
  Let $K_0$ be a compact convex subset of the plane $\mathbb R^2$, and assume
that $K_1\subseteq \mathbb R^2$ is similar to $K_0$, that is, $K_1$ is the
image of $K_0$ with respect to a similarity transformation $\mathbb
R^2\to\mathbb R^2$. Kira Adaricheva and Madina Bolat have recently proved that
if $K_0$ is a disk and both $K_0$ and $K_1$ are included in a triangle with
vertices $A_0$, $A_1$, and $A_2$, then there exist a $j\in \{0,1,2\}$ and a
$k\in\{0,1\}$ such that $K_{1-k}$ is included in the convex hull of
$K_k\cup(\{A_0,A_1, A_2\}\setminus\{A_j\})$. Here we prove that this property
characterizes disks among compact convex subsets of the plane. Actually, we
prove even more since we replace "similar" by "isometric" (also called
"congruent"). Circles are the boundaries of disks, so our result also gives a
characterization of circles.


title: Cryptographically verifiable anonymous voting using pan-european e-IDs

abstract:
  In this paper we explore a method to create anonymous services on top of the
STORK framework, to be used for electronic surveys or elections.
  The STORK project aims to realize a single electronic identification and
authentication area across Europe. For verifiable and anonymous voting, users
should be authenticated with their e-id (to prevent repeated voting) but the
votes should also be anonymous. This is achieved using blind signatures and an
onion routing system similar to the one used in TOR.
  In the paper we describe the anonymous voting protocol in detail, we analyze
a reference implementation and, finally, we highlight potential weaknesses and
propose some improvements.


title: Dictionary Learning with Equiprobable Matching Pursuit

abstract:
  Sparse signal representations based on linear combinations of learned atoms
have been used to obtain state-of-the-art results in several practical signal
processing applications. Approximation methods are needed to process
high-dimensional signals in this way because the problem to calculate optimal
atoms for sparse coding is NP-hard. Here we study greedy algorithms for
unsupervised learning of dictionaries of shift-invariant atoms and propose a
new method where each atom is selected with the same probability on average,
which corresponds to the homeostatic regulation of a recurrent convolutional
neural network. Equiprobable selection can be used with several greedy
algorithms for dictionary learning to ensure that all atoms adapt during
training and that no particular atom is more likely to take part in the linear
combination on average. We demonstrate via simulation experiments that
dictionary learning with equiprobable selection results in higher entropy of
the sparse representation and lower reconstruction and denoising errors, both
in the case of ordinary matching pursuit and orthogonal matching pursuit with
shift-invariant dictionaries. Furthermore, we show that the computational costs
of the matching pursuits are lower with equiprobable selection, leading to
faster and more accurate dictionary learning algorithms.


title: Twisted gauge theories in 3D Walker-Wang models

abstract:
  Three dimensional gauge theories with a discrete gauge group can emerge from
spin models as a gapped topological phase with fractional point excitations
(gauge charge) and loop excitations (gauge flux). It is known that 3D gauge
theories can be "twisted", in the sense that the gauge flux loops can have
nontrivial braiding statistics among themselves and such twisted gauge theories
are realized in models discovered by Dijkgraaf and Witten. A different
framework to systematically construct three dimensional topological phases was
proposed by Walker and Wang and a series of examples have been studied. Can the
Walker Wang construction be used to realize the topological order in twisted
gauge theories? This is not immediately clear because the Walker-Wang
construction is based on a loop condensation picture while the Dijkgraaf-Witten
theory is based on a membrane condensation picture. In this paper, we show that
the answer to this question is Yes, by presenting an explicit construction of
the Walker Wang models which realize both the twisted and untwisted gauge
theories with gauge group $\mathbb{Z}_2 \times \mathbb{Z}_2$. We identify the
topological order of the models by performing modular transformations on the
ground state wave functions and show that the modular matrices exactly match
those for the $\mathbb{Z}_2 \times \mathbb{Z}_2$ gauge theories. By relating
the Walker-Wang construction to the Dijkgraaf-Witten construction, our result
opens up a way to study twisted gauge theories with fermonic charges, and
correspondingly strongly interacting fermionic symmetry protected topological
phases and their surface states, through exactly solvable models.


title:
ViFi: Virtual Fingerprinting WiFi-based Indoor Positioning via
  Multi-Wall Multi-Floor Propagation Model

abstract:
  Widespread adoption of indoor positioning systems based on WiFi
fingerprinting is at present hindered by the large efforts required for
measurements collection during the offline phase. Two approaches were recently
proposed to address such issue: crowdsourcing and RSS radiomap prediction,
based on either interpolation or propagation channel model fitting from a small
set of measurements. RSS prediction promises better positioning accuracy when
compared to crowdsourcing, but no systematic analysis of the impact of system
parameters on positioning accuracy is available. This paper fills this gap by
introducing ViFi, an indoor positioning system that relies on RSS prediction
based on Multi-Wall Multi-Floor (MWMF) propagation model to generate a discrete
RSS radiomap (virtual fingerprints). Extensive experimental results, obtained
in multiple independent testbeds, show that ViFi outperforms virtual
fingerprinting systems adopting simpler propagation models in terms of
accuracy, and allows a sevenfold reduction in the number of measurements to be
collected, while achieving the same accuracy of a traditional fingerprinting
system deployed in the same environment. Finally, a set of guidelines for the
implementation of ViFi in a generic environment, that saves the effort of
collecting additional measurements for system testing and fine tuning, is
proposed.


title: Double Higgs production at the 14 TeV LHC and the 100 TeV pp-collider

abstract:
  We consider effective Higgs boson couplings, including both the CP-even and
CP-odd couplings, that affect Higgs boson pair production in this study.
Through the partial wave analysis, we find that the process $gg\to hh$ is
dominated by the $s$-wave component even at a 100~TeV $pp$-collider. Making use
of the $s$-wave kinematics, we propose a cut efficiency function to mimic the
collider simulation and obtain the potential of measuring Higgs effective
couplings at the 14~TeV LHC with an integrated luminosity of $3000~{\rm
fb}^{-1}$ and at a 100 TeV $pp$-collider. Analytical expressions of the
$2\sigma$ exclusion limits at the LHC and the $5\sigma$ discovery bands at the
100 TeV machine are given.