title:
Electrostatic Control over Temperature-Dependent Tunneling across a
  Single Molecule Junction

abstract:
  Understanding how the mechanism of charge transport through molecular tunnel
junctions depends on temperature is crucial to control electronic function in
molecular electronic devices. With just a few systems investigated as a
function of bias and temperature so far, thermal effects in molecular tunnel
junctions remain poorly understood. Here we report a detailed charge transport
study of an individual redox-active ferrocene-based molecule over a wide range
of temperatures and applied potentials. The results show the temperature
dependence of the current to vary strongly as a function of the gate voltage.
Specifically, the current across the molecule exponentially increases in the
Coulomb blockade regime and decreases at the charge degeneracy points, while
remaining temperature-independent at resonance. Our observations can be well
accounted for by a formal single-level tunneling model where the temperature
dependence relies on the thermal broadening of the Fermi distributions of the
electrons in the leads.


title: Hitting minors, subdivisions, and immersions in tournaments

abstract:
  The Erd\H{o}s-P\'osa property relates parameters of covering and packing of
combinatorial structures and has been mostly studied in the setting of
undirected graphs. In this note, we use results of Chudnovsky, Fradkin, Kim,
and Seymour to show that, for every directed graph $H$ (resp.
strongly-connected directed graph $H$), the class of directed graphs that
contain $H$ as a strong minor (resp. butterfly minor, topological minor) has
the vertex-Erd\H{o}s-P\'osa property in the class of tournaments. We also prove
that if $H$ is a strongly-connected directed graph, the class of directed
graphs containing $H$ as an immersion has the edge-Erd\H{o}s-P\'osa property in
the class of tournaments.


title: Probabilistic Inference Modulo Theories

abstract:
  We present SGDPLL(T), an algorithm that solves (among many other problems)
probabilistic inference modulo theories, that is, inference problems over
probabilistic models defined via a logic theory provided as a parameter
(currently, propositional, equalities on discrete sorts, and inequalities, more
specifically difference arithmetic, on bounded integers). While many solutions
to probabilistic inference over logic representations have been proposed,
SGDPLL(T) is simultaneously (1) lifted, (2) exact and (3) modulo theories, that
is, parameterized by a background logic theory. This offers a foundation for
extending it to rich logic languages such as data structures and relational
data. By lifted, we mean algorithms with constant complexity in the domain size
(the number of values that variables can take). We also detail a solver for
summations with difference arithmetic and show experimental results from a
scenario in which SGDPLL(T) is much faster than a state-of-the-art
probabilistic solver.


title:
Inferring biological networks by sparse identification of nonlinear
  dynamics

abstract:
  Inferring the structure and dynamics of network models is critical to
understanding the functionality and control of complex systems, such as
metabolic and regulatory biological networks. The increasing quality and
quantity of experimental data enable statistical approaches based on
information theory for model selection and goodness-of-fit metrics. We propose
an alternative method to infer networked nonlinear dynamical systems by using
sparsity-promoting $\ell_1$ optimization to select a subset of nonlinear
interactions representing dynamics on a fully connected network. Our method
generalizes the sparse identification of nonlinear dynamics (SINDy) algorithm
to dynamical systems with rational function nonlinearities, such as biological
networks. We show that dynamical systems with rational nonlinearities may be
cast in an implicit form, where the equations may be identified in the
null-space of a library of mixed nonlinearities including the state and
derivative terms; this approach applies more generally to implicit dynamical
systems beyond those containing rational nonlinearities. This method,
implicit-SINDy, succeeds in inferring three canonical biological models:
Michaelis-Menten enzyme kinetics, the regulatory network for competence in
bacteria, and the metabolic network for yeast glycolysis.


title: Semiparametric Estimation of Dynamic Discrete-Choice Models

abstract:
  We consider the estimation of dynamic discrete choice models in a
semiparametric setting, in which the per-period utility functions are known up
to a finite number of parameters, but the distribution of utility shocks is
left unspecified. This semiparametric setup differs from most of the existing
identification and estimation literature for dynamic discrete choice mod- els.
To show identification we derive and exploit a new Bellman-like recursive
representation for the unknown quantile function of the utility shocks. Our
estimators are straightforward to compute; some are simple and require no
iteration, and resemble classic estimators from the literature on
semiparametric regression and average derivative estimation. Monte Carlo
simulations demonstrate that our estimator performs well in small samples. To
highlight features of this estimator, we estimate a structural model of dynamic
labor supply for New York City taxicab drivers.


title:
Provable Efficient Online Matrix Completion via Non-convex Stochastic
  Gradient Descent

abstract:
  Matrix completion, where we wish to recover a low rank matrix by observing a
few entries from it, is a widely studied problem in both theory and practice
with wide applications. Most of the provable algorithms so far on this problem
have been restricted to the offline setting where they provide an estimate of
the unknown matrix using all observations simultaneously. However, in many
applications, the online version, where we observe one entry at a time and
dynamically update our estimate, is more appealing. While existing algorithms
are efficient for the offline setting, they could be highly inefficient for the
online setting.
  In this paper, we propose the first provable, efficient online algorithm for
matrix completion. Our algorithm starts from an initial estimate of the matrix
and then performs non-convex stochastic gradient descent (SGD). After every
observation, it performs a fast update involving only one row of two tall
matrices, giving near linear total runtime. Our algorithm can be naturally used
in the offline setting as well, where it gives competitive sample complexity
and runtime to state of the art algorithms. Our proofs introduce a general
framework to show that SGD updates tend to stay away from saddle surfaces and
could be of broader interests for other non-convex problems to prove tight
rates.


title:
Multi-threaded Geant4 on the Xeon-Phi with Complex High-Energy Physics
  Geometry

abstract:
  To study the performance of multi-threaded Geant4 for high-energy physics
experiments, an application has been developed which generalizes and extends
previous work. A highly-complex detector geometry is used for benchmarking on
an Intel Xeon Phi coprocessor. In addition, an implementation of parallel I/O
based on Intel SCIF and ROOT technologies is incorporated and studied.


title:
On constructing weight structures and extending them to idempotent
  extensions

abstract:
  We describe a new method for constructing a weight structure $w$ on a
triangulated category $C$.
  For a given $C$ and $w$ it allow us to give a fairly comprehensive (and new)
description of those triangulated categories consisting of retracts of objects
of $C$ (i.e., of subcategories of the Karoubi envelope of $C$ that contain $C$;
we call them idempotent extensions of $C$) such that $w$ extends to them. In
particular, any bounded above or below $w$ extends to any idempotent extension
of $C$. We also discuss the applications of our results to certain triangulated
categories of ("relative") motives.


title: Measuring cellular traction forces on non-planar substrates

abstract:
  Animal cells use traction forces to sense the mechanics and geometry of their
environment. Measuring these traction forces requires a workflow combining cell
experiments, image processing and force reconstruction based on elasticity
theory. Such procedures have been established before mainly for planar
substrates, in which case one can use the Green's function formalism. Here we
introduce a worksflow to measure traction forces of cardiac myofibroblasts on
non-planar elastic substrates. Soft elastic substrates with a wave-like
topology were micromolded from polydimethylsiloxane (PDMS) and fluorescent
marker beads were distributed homogeneously in the substrate. Using feature
vector based tracking of these marker beads, we first constructed a hexahedral
mesh for the substrate. We then solved the direct elastic boundary volume
problem on this mesh using the finite element method (FEM). Using data
simulations, we show that the traction forces can be reconstructed from the
substrate deformations by solving the corresponding inverse problem with a
L1-norm for the residue and a L2-norm for 0th order Tikhonov regularization.
Applying this procedure to the experimental data, we find that cardiac
myofibroblast cells tend to align both their shapes and their forces with the
long axis of the deformable wavy substrate.


title: Kronecker Determinantal Point Processes

abstract:
  Determinantal Point Processes (DPPs) are probabilistic models over all
subsets a ground set of $N$ items. They have recently gained prominence in
several applications that rely on "diverse" subsets. However, their
applicability to large problems is still limited due to the $\mathcal O(N^3)$
complexity of core tasks such as sampling and learning. We enable efficient
sampling and learning for DPPs by introducing KronDPP, a DPP model whose kernel
matrix decomposes as a tensor product of multiple smaller kernel matrices. This
decomposition immediately enables fast exact sampling. But contrary to what one
may expect, leveraging the Kronecker product structure for speeding up DPP
learning turns out to be more difficult. We overcome this challenge, and derive
batch and stochastic optimization algorithms for efficiently learning the
parameters of a KronDPP.


title:
Generalization Properties and Implicit Regularization for Multiple
  Passes SGM

abstract:
  We study the generalization properties of stochastic gradient methods for
learning with convex loss functions and linearly parameterized functions. We
show that, in the absence of penalizations or constraints, the stability and
approximation properties of the algorithm can be controlled by tuning either
the step-size or the number of passes over the data. In this view, these
parameters can be seen to control a form of implicit regularization. Numerical
results complement the theoretical findings.


title: Warburg's impedance revisited

abstract:
  The derivation of Warburg's impedance presented in several books and
scientific papers is reconsidered. It has been obtained by assuming that the
total electric current across the sample is just due to the diffusion, and that
the external potential applied to the electrode is responsible for an increase
of the bulk density of charge described by Nernst's model. We show that these
assumptions are not correct, and hence the proposed derivations questionable. A
correct determination of the electrochemical impedance of a cell of an
insulating material where are injected external charges of a given sign, when
the diffusion and the displacement currents are taken into account, does not
predict, in the high frequency region, for the real and imaginary parts of the
impedance, the trends predicted by Warburg's impedance in the Nernstian
approximation. The presented model can be generalized to the case of asymmetric
cell, assuming boundary conditions physically sound.


title:
Secondary radiation measurements for particle therapy applications:
  prompt photons produced by $^{4}$He, $^{12}$C and $^{16}$O ion beams in a
  PMMA target

abstract:
  Charged particle beams are used in Particle Therapy (PT) to treat oncological
patients due to their selective dose deposition in tissues and to their high
biological effect in killing cancer cells with respect to photons and electrons
used in conventional radiotherapy. Nowadays, protons and carbon ions are used
in PT clinical routine but, recently, the interest on the potential application
of helium and oxygen beams is growing due to their reduced multiple scattering
inside the body and increased linear energy transfer, relative biological
effectiveness and oxygen enhancement ratio. The precision of PT demands for
online dose monitoring techniques, crucial to improve the quality assurance of
treatments. The beam range confined in the irradiated target can be monitored
thanks to the neutral or charged secondary radiation emitted by the
interactions of hadron beams with matter. Prompt photons are produced by
nuclear de-excitation processes and, at present, different dose monitoring and
beam range verification techniques based on the prompt {\gamma} detection have
been proposed. It is hence of importance to perform the {\gamma} yield
measurement in therapeutical-like conditions. In this paper we report the
yields of prompt photons produced by the interaction of helium, carbon and
oxygen ion beams with a PMMA target. The measurements were performed at the
Heidelberg Ion-beam Therapy center (HIT) with beams of different energies. A
LYSO scintillator has been used as photon detector. The obtained {\gamma}
yields for $^{12}$C ion beams are compared with results from literature, while
no other results from $^{4}$He and $^{16}$O beams have been published yet. A
discussion on the expected resolution of a slit camera detector is presented,
demonstrating the feasibility of a prompt-{\gamma} based monitoring technique
for PT treatments using helium, carbon and oxygen ion beams.


title: Newtonian Cosmology with a Quantum Bounce

abstract:
  It has been known for some time that the cosmological Friedmann equation
deduced from General Relativity can be also obtained within the Newtonian
framework under certain assumptions. We use this result together with quantum
corrections to the Newtonian potentials to derive a set a of quantum corrected
Friedmann equations. We examine the behavior of the solutions of these modified
cosmological equations paying special attention to the sign of the quantum
corrections. We find different quantum effects crucially depending on this
sign. One such a solution displays a qualitative resemblance to other quantum
models like Loop Quantum Gravity or non-commutative geometry.


title:
Determination of the Total Solar Modulation Factors in the Heliosphere
  For Cosmic Ray Protons and Electrons by Comparing Interstellar Spectra
  Deduced from Voyager Measurements and PAMELA Spectra of These Particles at
  the Earth

abstract:
  We have determined the interstellar spectra of cosmic ray protons and
electrons from a few MeV to ~10 GeV. These interstellar spectra are based on
Voyager data and a normalization of specific galactic propagation model
calculations of both protons and electrons to PAMELA data at the Earth at 10
GeV, where the solar modulation is small. These resulting interstellar spectra
are then compared with spectra of protons and electrons measured at lower
energies at the Earth by PAMELA in 2009. The total amount of modulation at
lower rigidities (energies) is found to be nearly the same at the same rigidity
for both protons and electrons and ranges in magnitude from a factor ~400 at
0.1 GV for electrons, to a factor ~15 at 0.44 GV (100 MeV for protons), to a
factor ~3.3 at 1 GV for both components. The magnitude of this total modulation
of both components are the same to within + 10% from ~0.3 to ~3 GV in rigidity.
The observed total modulation for protons can be matched quite closely using a
simple spherically symmetric modulation picture involving a force field model
for the modulation and a constant energy loss at all energies. The electrons
require a set of parameters to calculate more detailed features of the
modulation using the diffusion coefficient and its variation with rigidity and
radius at rigidities less than few GV.


title:
Active Control of Probability Amplitudes in a Mesoscale System via
  Feedback-Induced Suppression of Dissipation and Noise

abstract:
  We introduce a classical potentiostatic feedback mechanism that attenuates
the dissipation in a quantum system arising from coupling to the surrounding
thermodynamic bath, preserving the inter-state interference in an electronic
excitation transfer (EET) process. A three-terminal potentiostat device applies
a low-noise voltage bias to the terminals of the EET system and reduces the
physical coupling between the quantum system and its environment. We introduce
a classical equivalent circuit to model the environment-coupled excitation
transfer in an elementary two-state system. This model provides qualitative
insight into how classical feedback action affects the transition probabilities
between the states and selectively reduces the dissipative coupling for one of
the vibronic energy levels of the transfer system. Furthermore, we show that
negative feedback results in persistent spectral coherence between the energy
level of the decoupled state and the vibronic levels of the complementary
state, making the decoupled vibronic channel a probe for characterizing the
vibronic structure of the complementary channel of the EET system.


title:
On Modeling Coverage and Rate of Random Cellular Networks under Generic
  Channel Fading

abstract:
  In this paper we provide an analytic framework for computing the expected
downlink coverage probability, and the associated data rate of cellular
networks, where base stations are distributed in a random manner. The provided
expressions are in computable integral forms that accommodate generic channel
fading conditions. We develop these expressions by modelling the cellular
interference using stochastic geometry analysis, then we employ them for
comparing the coverage resulting from various channel fading conditions namely
Rayleigh and Rician fading, in addition to the fading-less channel.
Furthermore, we expand the work to accommodate the effects of random frequency
reuse on the cellular coverage and rate. Monte-Carlo simulations are conducted
to validate the theoretical analysis, where the results show a very close
match.


title: Rank parity for congruent supersingular elliptic curves

abstract:
  A recent paper of Shekhar compares the ranks of elliptic curves $E_1$ and
$E_2$ for which there is an isomorphism $E_1[p] \simeq E_2[p]$ as
$\mathrm{Gal}(\bar{\mathbf{Q}}/\mathbf{Q})$-modules, where $p$ is a prime of
good ordinary reduction for both curves. In this paper we prove an analogous
result in the case where $p$ is a prime of good supersingular reduction.


title:
The number of cycles in random permutations without long cycles is
  asymptotically Gaussian

abstract:
  For uniform random permutations conditioned to have no long cycles, we prove
that the total number of cycles satisfies a central limit theorem. Under
additional assumptions on the asymptotic behavior of the set of allowed cycle
lengths, we derive asymptotic expansions for the corresponding expected value
and variance.


title: Quantum Router with Network Coding

abstract:
  Many protocols of quantum information processing, like quantum key
distribution or measurement-based quantum computation, "consume" entangled
quantum states during their execution. When participants are located at distant
sites, these resource states need to be distributed. Due to transmission losses
quantum repeater become necessary for large distances (e.g. $\gtrsim$ 300 km).
Here we generalize the concept of the graph state repeater to $D$-dimensional
graph states and to repeaters that can perform basic measurement-based quantum
computations, which we call quantum routers. This processing of data at
intermediate network nodes is called quantum network coding. We describe how a
scheme to distribute general two-colorable graph states via quantum routers
with network coding can be constructed from classical linear network codes. The
robustness of the distribution of graph states against outages of network nodes
is analysed by establishing a link to stabilizer error correction codes.
Furthermore we show, that for any stabilizer error correction code there exists
a corresponding quantum network code with similar error correcting
capabilities.


title:
Comparative study of gyrokinetic, hybrid-kinetic and fully kinetic wave
  physics for space plasmas

abstract:
  A set of numerical solvers for the linear dispersion relations of the
gyrokinetic, the hybrid-kinetic, and the fully kinetic model is employed to
study the physics of the kinetic Alfv\'en wave and the fast magnetosonic mode
in these models. In particular, we focus on parameters that are relevant for
solar wind oriented applications (using a homogeneous, isotropic background),
which are characterized by wave propagation angles averaging close to 90{\deg}.
It is found that the gyrokinetic model, while lacking high-frequency solutions
and cyclotron effects, faithfully reproduces the fully kinetic Alfv\'en wave
physics close to, and sometimes significantly beyond, the boundaries of its
range of validity. The hybrid-kinetic model, on the other hand, is much more
complete in terms of high-frequency waves, but owing to its simple electron
model it is found to severely underpredict wave damping rates even on ion
spatial scales across a large range of parameters, despite containing full
kinetic ion physics.


title: Heat-bath random walks with Markov bases

abstract:
  Graphs on lattice points are studied whose edges come from a finite set of
allowed moves of arbitrary length. We show that the diameter of these graphs on
fibers of a fixed integer matrix can be bounded from above by a constant. We
then study the mixing behaviour of heat-bath random walks on these graphs. We
also state explicit conditions on the set of moves so that the heat-bath random
walk, a generalization of the Glauber dynamics, is an expander in fixed
dimension.


title: Notes on frequencies and timescales in nonequilibrium Green's functions

abstract:
  We discuss the ringdown behavior of the nonequilibrium Green's function in a
strongly coupled theory with the holographic dual with a focus on
quasinormal-mode equilibration. We study the time resolved spectral function
for a probe scalar in Vaidya-AdS spacetime in detail as a complement to the
preceding work arXiv:1603.06935 using further numerical results in very
nonadiabatic temperature changes. It is shown that the relaxation of the
nonequilibrium spectral function obtained through the Wigner transform is
governed by the lowest quasinormal mode frequency. The timescale of the
background temperature change is also observed in the frequency analysis. We
then consider a toy model motivated by the quasinormal mode behavior and
discuss these main features in numerical results are simply realized.


title:
Computational Design Of Surfaces, Nanostructures and Optoelectronic
  Materials

abstract:
  Properties of engineering materials are generally influenced by defects such
as point defects (vacancies, interstitials, substitutional defects), line
defects (dislocations), planar defects (grain boundaries, free
surfaces/nanostructures, interfaces, stacking faults) and volume defects
(voids). Classical physics based molecular dynamics and quantum physics based
density functional theory can be useful in designing materials with controlled
defect properties. In this thesis, empirical potential based molecular dynamics
was used to study the surface modification of polymers due to energetic
polyatomic ion, thermodynamics and mechanics of metal-ceramic interfaces and
nanostructures, while density functional theory was used to screen substituents
in optoelectronic materials.


title:
Impact of the neutron matter equation of state on neutron skin and
  neutron drip lines in chiral effective field theory

abstract:
  We present predictions of the binding energy per nucleon and the neutron skin
thickness in highly neutron-rich isotopes of Oxygen, Magnesium, and Aluminum.
The calculations are carried out at and below the neutron drip line as
predicted by our model. The nuclear properties are obtained via an energy
functional whose input is the equation of state of isospin-asymmetric infinite
matter. The latter is based on a microscopic derivation of the energy per
particle in neutron matter applying chiral few-nucleon forces together with a
phenomenological model for the equation of state of symmetric nuclear matter.
We highlight the impact of the neutron matter equation of state at different
orders of chiral effective field theory on neutron skins and the binding energy
per particle and quantify the uncertainty carried by our predictions.


title:
Estimation of Passenger Route Choice Pattern Using Smart Card Data for
  Complex Metro Systems

abstract:
  Nowadays, metro systems play an important role in meeting the urban
transportation demand in large cities. The understanding of passenger route
choice is critical for public transit management. The wide deployment of
Automated Fare Collection(AFC) systems opens up a new opportunity. However,
only each trip's tap-in and tap-out timestamp and stations can be directly
obtained from AFC system records; the train and route chosen by a passenger are
unknown, which are necessary to solve our problem. While existing methods work
well in some specific situations, they don't work for complicated situations.
In this paper, we propose a solution that needs no additional equipment or
human involvement than the AFC systems. We develop a probabilistic model that
can estimate from empirical analysis how the passenger flows are dispatched to
different routes and trains. We validate our approach using a large scale data
set collected from the Shenzhen metro system. The measured results provide us
with useful inputs when building the passenger path choice model.


title:
Absolute semi-deviation risk measure for ordering problem with
  transportation cost in Supply Chain

abstract:
  We present a decomposition method for stochastic programs with 0-1 variables
in the second-stage with absolute semi-deviation (ASD) risk measure.
Traditional stochastic programming models are risk-neutral where expected costs
are considered for the second-stage. A common approach to address risk is to
include a dispersion statistic in addition with expected costs and weighted
appropriately. Due to the lack of block angular structure, stochastic programs
with ASD risk-measure possess computational challenges. The proposed
decomposition algorithm uses another risk-measure `expected excess', and
provides tighter bounds for ASD stochastic models. We perform computational
study on a supply chain replenishment problem and standard knapsack instances.
The computational results using supply chain instances demonstrate the
usefulness of ASD risk-measure in decision making under uncertainty, and
knapsack instances indicate that the proposed methodology outperforms a direct
solver.


title:
Liouville first passage percolation: the weight exponent is strictly
  less than 1 at high temperatures

abstract:
  Let $\{\eta_{N, v}: v\in V_N\}$ be a discrete Gaussian free field in a
two-dimensional box $V_N$ of side length $N$ with Dirichlet boundary
conditions. We study the Liouville first passage percolation, i.e., the
shortest path metric where each vertex is given a weight of $e^{\gamma \eta_{N,
v}}$ for some $\gamma>0$. We show that for sufficiently small but fixed
$\gamma>0$, the expected Liouville FPP distance between any pair of vertices is
$O(N^{1-\gamma^2/10^3})$.


title:
Mechanical properties of metal decorated graphyne, graphyne-BN-yne, and
  BN-yne sheets

abstract:
  In this paper, the mechanical properties of two-dimensional structures of
metal decoration systems of simple graphyne (CC), analogous system of BN sheet
(BN-yne), also the graphyne-BN sheet (CC-BN-yne) was investigated. The
properties such as Young and Bulk moduli were studied using Energy-Strain
correlation. We introduced calculations based on density functional theory
(DFT); the generalized gradient approximation (GGA) framework was used in this
regard. The results demonstrated very competitive values for Young and Bulk
moduli of the Pt decorated CC and BN-yne. However, the CC-BN-yne structure
defined around 80% of Young and 77% of Bulk values of that of pure structures.
Also Na decorated ones were examined and the results showed the same trend for
all three structures. The CC-BN-yne defined the lowest values for either Young
or Bulk moduli.


title:
Fermionic boundary modes in two-dimensional noncentrosymmetric
  superconductors

abstract:
  We calculate the spectrum of the Andreev boundary modes in a two-dimensional
superconductor formed at an interface between two different non-superconducting
materials, e.g. insulating oxides. Inversion symmetry is absent in this system,
and both the electron band structure and the superconducting pairing are
strongly affected by the spin-orbit coupling of the Rashba type. We consider
isotropic s-wave pairing states, both with and without time-reversal symmetry
breaking, as well as various d-wave states. In all cases, there exist subgap
Andreev boundary states, whose properties, in particular, the number and
location of the zero-energy modes, qualitatively depend on the gap symmetry and
the spin-orbit coupling strength.


title: Explicit Salem Sets in $\mathbb{R}^2$

abstract:
  We construct explicit (i.e., non-random) examples of Salem sets in
$\mathbb{R}^2$ of dimension $s$ for every $0 \leq s \leq 2$. In particular, we
give the first explicit examples of Salem sets in $\mathbb{R}^2$ of dimension
$0 < s < 1$. This extends a theorem of Kaufman.


title: Robust Downbeat Tracking Using an Ensemble of Convolutional Networks

abstract:
  In this paper, we present a novel state of the art system for automatic
downbeat tracking from music signals. The audio signal is first segmented in
frames which are synchronized at the tatum level of the music. We then extract
different kind of features based on harmony, melody, rhythm and bass content to
feed convolutional neural networks that are adapted to take advantage of each
feature characteristics. This ensemble of neural networks is combined to obtain
one downbeat likelihood per tatum. The downbeat sequence is finally decoded
with a flexible and efficient temporal model which takes advantage of the
metrical continuity of a song. We then perform an evaluation of our system on a
large base of 9 datasets, compare its performance to 4 other published
algorithms and obtain a significant increase of 16.8 percent points compared to
the second best system, for altogether a moderate cost in test and training.
The influence of each step of the method is studied to show its strengths and
shortcomings.


title: Domain Transfer Multi-Instance Dictionary Learning

abstract:
  In this paper, we invest the domain transfer learning problem with
multi-instance data. We assume we already have a well-trained multi-instance
dictionary and its corresponding classifier from the source domain, which can
be used to represent and classify the bags. But it cannot be directly used to
the target domain. Thus we propose to adapt them to the target domain by adding
an adaptive term to the source domain classifier. The adaptive function is a
linear function based a domain transfer multi-instance dictionary. Given a
target domain bag, we first map it to a bag-level feature space using the
domain transfer dictionary, and then apply a the linear adaptive function to
its bag-level feature vector. To learn the domain-transfer dictionary and the
adaptive function parameter, we simultaneously minimize the average
classification error of the target domain classifier over the target domain
training set, and the complexities of both the adaptive function parameter and
the domain transfer dictionary. The minimization problem is solved by an
iterative algorithm which update the dictionary and the function parameter
alternately. Experiments over several benchmark data sets show the advantage of
the proposed method over existing state-of-the-art domain transfer
multi-instance learning methods.


title: G-Extensions of Quantum Group Categories and Functorial SPT

abstract:
  In this short mostly expository note, we sketch a program for gauging fully
extended topological field theories in 3 dimensions. One begins with the
spherical fusion category with which one wants to do Levin-Wen or Turaev-Viro.
One then computes a homotopic space with certain $\pi_\bullet$ given by
autoequivalences, invertible objects and the ground (algebraic) field. Then for
each desired symmetry group $G$ one looks at mapping $BG$ into that. This
classifies equivalence classes of G-extended fusion categories. This is an
equivalence at a fully extended level so will allow many defects rather than
only evaluating partition functions on closed manifolds. We can now use these
categories to build a new fully extended 3d topological field theory, but now
possibly with extra data. This is the result of permeating defect walls and
saying how that affects the assignment to the point strata.


title:
A study of the elements copper through uranium in Sirius A:
  Contributions from STIS and ground-based spectra

abstract:
  We determine abundances or upper limits for all of the 55 stable elements
from copper to uranium for the A1 Vm star Sirius. The purpose of the study is
to assemble the most complete picture of elemental abundances with the hope of
revealing the chemical history of the brightest star in the sky, apart from the
Sun. We also explore the relationship of this hot metallic-line (Am) star to
its cooler congeners, as well as the hotter, weakly- or non-magnetic
mercury-manganese (HgMn) stars. Our primary observational material consists of
{\em Hubble Space Telescope} ($HST$) spectra taken with the Space Telescope
Imaging Spectrograph (STIS) in the ASTRAL project. We have also used archival
material from the %\citep/{ayr10}. $COPERNICUS$ satellite, and from the $HST$
Goddard High-Resolution Spectrograph (GHRS), as well as ground-based spectra
from Furenlid, Westin, Kurucz, Wahlgren, and their coworkers, ESO spectra from
the UVESPOP project, and NARVAL spectra retrieved from PolarBase. Our analysis
has been primarily by spectral synthesis, and in this work we have had the
great advantage of extensive atomic data unavailable to earlier workers. We
find most abundances as well as upper limits range from 10 to 100 times above
solar values. We see no indication of the huge abundance excesses of 1000 or
more that occur among many chemically peculiar (CP) stars of the upper main
sequence. The picture of Sirius as a hot Am star is reinforced.


title:
Total Variation Classes Beyond 1d: Minimax Rates, and the Limitations of
  Linear Smoothers

abstract:
  We consider the problem of estimating a function defined over $n$ locations
on a $d$-dimensional grid (having all side lengths equal to $n^{1/d}$). When
the function is constrained to have discrete total variation bounded by $C_n$,
we derive the minimax optimal (squared) $\ell_2$ estimation error rate,
parametrized by $n$ and $C_n$. Total variation denoising, also known as the
fused lasso, is seen to be rate optimal. Several simpler estimators exist, such
as Laplacian smoothing and Laplacian eigenmaps. A natural question is: can
these simpler estimators perform just as well? We prove that these estimators,
and more broadly all estimators given by linear transformations of the input
data, are suboptimal over the class of functions with bounded variation. This
extends fundamental findings of Donoho and Johnstone [1998] on 1-dimensional
total variation spaces to higher dimensions. The implication is that the
computationally simpler methods cannot be used for such sophisticated denoising
tasks, without sacrificing statistical accuracy. We also derive minimax rates
for discrete Sobolev spaces over $d$-dimensional grids, which are, in some
sense, smaller than the total variation function spaces. Indeed, these are
small enough spaces that linear estimators can be optimal---and a few
well-known ones are, such as Laplacian smoothing and Laplacian eigenmaps, as we
show. Lastly, we investigate the problem of adaptivity of the total variation
denoiser to these smaller Sobolev function spaces.


title: Dense Volume-to-Volume Vascular Boundary Detection

abstract:
  In this work, we present a novel 3D-Convolutional Neural Network (CNN)
architecture called I2I-3D that predicts boundary location in volumetric data.
Our fine-to-fine, deeply supervised framework addresses three critical issues
to 3D boundary detection: (1) efficient, holistic, end-to-end volumetric label
training and prediction (2) precise voxel-level prediction to capture fine
scale structures prevalent in medical data and (3) directed multi-scale,
multi-level feature learning. We evaluate our approach on a dataset consisting
of 93 medical image volumes with a wide variety of anatomical regions and
vascular structures. In the process, we also introduce HED-3D, a 3D extension
of the state-of-the-art 2D edge detector (HED). We show that our deep learning
approach out-performs, the current state-of-the-art in 3D vascular boundary
detection (structured forests 3D), by a large margin, as well as HED applied to
slices, and HED-3D while successfully localizing fine structures. With our
approach, boundary detection takes about one minute on a typical 512x512x512
volume.


title:
A K-theoretical Invariant and Bifurcation for Homoclinics of Hamiltonian
  Systems

abstract:
  We revisit a K-theoretical invariant that was invented by the first author
some years ago for studying multiparameter bifurcation of branches of critical
points of functionals. Our main aim is to apply this invariant to investigate
bifurcation of homoclinic solutions of families of Hamiltonian systems which
are parametrised by tori.


title: Fast plurality consensus in regular expanders

abstract:
  Pull voting is a classic method to reach consensus among $n$ vertices with
differing opinions in a distributed network: each vertex at each step takes on
the opinion of a random neighbour. This method, however, suffers from two
drawbacks. Even if there are only two opposing opinions, the time taken for a
single opinion to emerge can be slow and the final opinion is not necessarily
the initially held majority.
  We refer to a protocol where 2 neighbours are contacted at each step as a
2-sample voting protocol. In the two-sample protocol a vertex updates its
opinion only if both sampled opinions are the same. Not much was known about
the performance of two-sample voting on general expanders in the case of three
or more opinions. In this paper we show that the following performance can be
achieved on a $d$-regular expander using two-sample voting. We suppose there
are $k \ge 3$ opinions, and that the initial size of the largest and second
largest opinions is $A_1, A_2$ respectively.
  We prove that, if $A_1 - A_2 \ge C n \max\{\sqrt{(\log n)/A_1}, \lambda\}$,
where $\lambda$ is the absolute second eigenvalue of matrix $P=Adj(G)/d$ and
$C$ is a suitable constant, then the largest opinion wins in $O((n \log
n)/A_1)$ steps with high probability.
  For almost all $d$-regular graphs, we have $\lambda=c/\sqrt{d}$ for some
constant $c>0$. This means that as $d$ increases we can separate an opinion
whose majority is $o(n)$, whereas $\Theta(n)$ majority is required for $d$
constant.
  This work generalizes the results of Becchetti et. al (SPAA 2014) for the
complete graph $K_n$.


title:
Some Classes of Gravitational Shock Waves from Higher Order Theories of
  Gravity

abstract:
  We study the gravitational shock wave generated by a massless high energy
particle in the context of higher order gravities of the form $F(R,R_{\mu
\nu}R^{\mu \nu},R_{\mu \nu \alpha \beta}R^{\mu \nu \alpha \beta})$. In the case
of $F(R)$ gravity, we investigate the gravitational shock wave solutions
corresponding to various cosmologically viable gravities, and as we demonstrate
the solutions are rescaled versions of the Einstein-Hilbert gravity solution.
Interestingly enough, other higher order gravities result to the general
relativistic solution, except for some specific gravities of the form $F(R_{\mu
\nu}R^{\mu \nu})$ and $F(R,R_{\mu \nu}R^{\mu \nu})$, which we study in detail.
In addition, when realistic Gauss-Bonnet gravities of the form
$R+F(\mathcal{G})$ are considered, the gravitational shock wave solutions are
identical to the general relativistic solution. Finally, the singularity
structure of the gravitational shock waves solutions is studied, and it is
shown that the effect of higher order gravities makes the singularities milder
in comparison to the general relativistic solutions, and in some particular
cases the singularities seem to be absent.


title: Attraction-induced jamming in the flow of foam through a channel

abstract:
  We study the flow of a pressure-driven foam through a straight channel using
numerical simulations, and examine the effects of a tuneable attractive
potential between bubbles. This potential, which accounts for the effects of
disjoining pressure in the liquid films between separating bubbles, is shown
here to introduce jamming and stick-slip flow in a straight channel. We report
on the behaviour of these new regimes by varying the strength of the attractive
potential. It is seen that there is a force threshold below which the flow
jams, and on increasing the driving force, a cross over from intermittent
(stick-slip) to smooth flow is observed. This threshold force below which the
foam jams increases linearly with the strength of the attractive potential. By
examining the spectra of energy fluctuations, we show that stick-slip flow is
characterized by low frequency rearrangements and strongly local behaviour,
whereas steady flow shows a broad spectrum of energy drop events and collective
behaviour. Our work suggests that the stick-slip and the jamming regimes occur
due to the increased stabilization of contact networks by the attractive
potential - as the strength of attraction is increased, bubbles are
increasingly trapped within networks, and there is a decrease in the number of
contact changes.


title: MAD Adaptive Optics Imaging of High Luminosity Quasars: A Pilot Project

abstract:
  We present near-IR images of five luminous quasars at z~2 and one at z~4
obtained with an experimental adaptive optics instrument at the ESO Very Large
Telescope. The observations are part of a program aimed at demonstrating the
capabilities of multi-conjugated adaptive optics imaging combined with the use
of natural guide stars for high spatial resolution studies on large telescopes.
The observations were mostly obtained under poor seeing conditions but in two
cases. In spite of these non optimal conditions, the resulting images of point
sources have cores of FWHM ~0.2 arcsec. We are able to characterize the host
galaxy properties for 2 sources and set stringent upper limits to the galaxy
luminosity for the others. We also report on the expected capabilities for
investigating the host galaxies of distant quasars with adaptive optics systems
coupled with future Extremely Large Telescopes. Detailed simulations show that
it will be possible to characterize compact (2-3 kpc) quasar host galaxies for
QSOs at z = 2 with nucleus K-magnitude spanning from 15 to 20 (corresponding to
absolute magnitude -31 to -26) and host galaxies that are 4 mag fainter than
their nuclei.


title: Topologically protected modes in non-equilibrium stochastic systems

abstract:
  Non-equilibrium driving of biochemical reactions is believed to enable their
robust functioning despite the presence of thermal fluctuations and other
sources of disorder. Such robust functions include sensory adaptation, enhanced
enyzmatic specificity and maintenance of coherent oscillations. Non-equilibrium
biochemical reactions can be modeled as a master equation whose rate constants
break detailed balance. We find that non equilibrium fluxes can support
topologically protected boundary modes that resemble similar modes in
electronic and mechanical systems. We show that when a biochemical network can
be decomposed into two ordered bulks that meet at a possibly disordered
interferace, the ordered bulks can be each associated with a topologically
invariant winding number. If the winding numbers are mismatched, we are
guaranteed that the steady state distribution is localized at the interface
between the bulks, even in the presence of strong disorder in reaction rates.
We argue that our work provides a framework for how biochemical systems can use
non equilibrium driving to achieve robust function.


title: First Forcer results on deep-inelastic scattering and related quantities

abstract:
  We present results on the fourth-order splitting functions and coefficient
functions obtained using Forcer, a four-loop generalization of the Mincer
program for the parametric reduction of self-energy integrals. We have computed
the respective lowest three even-N and odd-N moments for the non-singlet
splitting functions and the non-singlet coefficient functions in
electromagnetic and nu+nu(bar) charged-current deep-inelastic scattering, and
the N=2 and N=4 results for the corresponding flavour-singlet quantities.
Enough moments have been obtained for an LLL-based determination of the
analytic N-dependence of the nf^3 and nf^2 parts, respectively, of the singlet
and non-singlet splitting functions. The large-N limit of the latter provides
the complete nf^2 contributions to the four-loop cusp anomalous dimension. Our
results also provide additional evidence of a non-vanishing contribution of
quartic group invariants to the cusp anomalous dimension.


title: Agent-based model of information spread in social networks

abstract:
  We propose evolution rules of the multiagent network and determine
statistical patterns in life cycle of agents - information messages. The main
discussed statistical pattern is connected with the number of likes and reposts
for a message. This distribution corresponds to Weibull distribution according
to modeling results. We examine proposed model using the data from Twitter, an
online social networking service.


title:
Influence Activation Model: A New Perspective in Social Influence
  Analysis and Social Network Evolution

abstract:
  What drives the propensity for the social network dynamics? Social influence
is believed to drive both off-line and on-line human behavior, however it has
not been considered as a driver of social network evolution. Our analysis
suggest that, while the network structure affects the spread of influence in
social networks, the network is in turn shaped by social influence activity
(i.e., the process of social influence wherein one person's attitudes and
behaviors affect another's). To that end, we develop a novel model of network
evolution where the dynamics of network follow the mechanism of influence
propagation, which are not captured by the existing network evolution models.
Our experiments confirm the predictions of our model and demonstrate the
important role that social influence can play in the process of network
evolution. As well exploring the reason of social network evolution, different
genres of social influence have been spotted having different effects on the
network dynamics. These findings and methods are essential to both our
understanding of the mechanisms that drive network evolution and our knowledge
of the role of social influence in shaping the network structure.


title:
Heavy Higgs decay to $t\bar{t} Z$ and constraints on a $750$ GeV
  pseudoscalar

abstract:
  In models with multiple nondegenerate Higgs bosons, the decay chain $H/A \to
A/H Z\to t\bar{t} Z$ may have a partial width comparable to the $t\bar{t}$
decay mode. We recast the ATLAS standard model $t\bar{t} Z$ measurement to put
limits on the rate for this process. Limits are also set on the two Higgs
doublet model at low $\tan \beta$ that are sensitive to a heavy Higgs mass as
high as $\sim 750$ GeV. We then discuss the $750$ GeV diphoton excess in terms
of a pseudoscalar that also has the decays $A\to HZ$ and $A\to H^\pm W^\mp$.
These decays strongly constrain the partial widths for $A\to\gamma\gamma$ and
$A\to gg$ when combined with the $t\bar t$ resonance search limits. In a
benchmark model the mass of $H$ should be close to 650 GeV.


title: CITlab ARGUS for historical handwritten documents

abstract:
  We describe CITlab's recognition system for the HTRtS competition attached to
the 13. International Conference on Document Analysis and Recognition, ICDAR
2015. The task comprises the recognition of historical handwritten documents.
The core algorithms of our system are based on multi-dimensional recurrent
neural networks (MDRNN) and connectionist temporal classification (CTC). The
software modules behind that as well as the basic utility technologies are
essentially powered by PLANET's ARGUS framework for intelligent text
recognition and image processing.


title: Advancing the State-of-the-Art in Hardware Trojans Design

abstract:
  Electronic Design Automation (EDA) industry heavily reuses third party IP
cores. These IP cores are vulnerable to insertion of Hardware Trojans (HTs) at
design time by third party IP core providers or by malicious insiders in the
design team. State of the art research has shown that existing HT detection
techniques, which claim to detect all publicly available HT benchmarks, can
still be defeated by carefully designing new sophisticated HTs. The reason
being that these techniques consider the HT landscape to be limited only to the
publicly known HT benchmarks, or other similar (simple) HTs. However the
adversary is not limited to these HTs and may devise new HT design principles
to bypass these countermeasures.
  In this paper, we discover certain crucial properties of HTs which lead to
the definition of an exponentially large class of Deterministic Hardware
Trojans $H_D$ that an adversary can (but is not limited to) design. The
discovered properties serve as HT design principles, based on which we design a
new HT called 'XOR-LFSR' and present it as a 'proof-of-concept' example from
the class $H_D$. These design principles help us understand the tremendous ways
an adversary has to design a HT, and show that the existing publicly known HT
benchmarks are just the tip of the iceberg on this huge landscape. This work,
therefore, stresses that instead of guaranteeing a certain (low) false negative
rate for a small constant set of publicly known HTs, a rigorous HT detection
tool should take into account these newly discovered HT design principles and
hence guarantee the detection of an exponentially large class (exponential in
number of wires in IP core) of HTs with negligible false negative rate.


title: The frog model with drift on R

abstract:
  Consider a Poisson process on $\mathbb{R}$ with intensity $f$ where $0 \leq
f(x)<\infty$ for ${x}\geq 0$ and ${f(x)}=0$ for $x<0$. The "points" of the
process represent sleeping frogs. In addition, there is one active frog
initially located at the origin. At time ${t}=0$ this frog begins performing
Brownian motion with leftward drift $\lambda$ (i.e. its motion is a random
process of the form ${B}_{t}-\lambda {t}$). Any time an active frog arrives at
a point where a sleeping frog is residing, the sleeping frog becomes active and
begins performing Brownian motion with leftward drift $\lambda$, independently
of the motion of all of the other active frogs. This paper establishes sharp
conditions on the intensity function $f$ that determine whether the model is
transient (meaning the probability that infinitely many frogs return to the
origin is 0), or non-transient (meaning this probability is greater than 0). A
discrete model with $\text{Poiss}(f(n))$ sleeping frogs at positive integer
points (and where activated frogs perform biased random walks on $\mathbb{Z}$)
is also examined. In this case as well, we obtain a similar sharp condition on
$f$ corresponding to transience of the model.


title: Structure-based control of complex networks with nonlinear dynamics

abstract:
  What can we learn about controlling a system solely from its underlying
network structure? Here we adapt a recently developed framework for control of
networks governed by a broad class of nonlinear dynamics that includes the
major dynamic models of biological, technological, and social processes. This
feedback-based framework provides realizable node overrides that steer a system
towards any of its natural long term dynamic behaviors, regardless of the
specific functional forms and system parameters. We use this framework on
several real networks, identify the topological characteristics that underlie
the predicted node overrides, and compare its predictions to those of
structural controllability in control theory. Finally, we demonstrate this
framework's applicability in dynamic models of gene regulatory networks and
identify nodes whose override is necessary for control in the general case, but
not in specific model instances.

categories: cond-mat.dis-nn cs.SY physics.soc-ph q-bio.MN


title:
A nearly tight upper bound on tri-colored sum-free sets in
  characteristic 2

abstract:
  A tri-colored sum-free set in an abelian group $H$ is a collection of ordered
triples in $H^3$, $\{(a_i,b_i,c_i)\}_{i=1}^m$, such that the equation
$a_i+b_j+c_k=0$ holds if and only if $i=j=k$. Using a variant of the lemma
introduced by Croot, Lev, and Pach in their breakthrough work on
arithmetic-progression-free sets, we prove that the size of any tri-colored
sum-free set in $\mathbb{F}_2^n$ is bounded above by $6 {n \choose \lfloor n/3
\rfloor}$. This upper bound is tight, up to a factor subexponential in $n$:
there exist tri-colored sum-free sets in $\mathbb{F}_2^n$ of size greater than
${n \choose \lfloor n/3 \rfloor} \cdot 2^{-\sqrt{16 n / 3}}$ for all
sufficiently large $n$.


title: Emergence of the XY-like phase in the deformed spin-3/2 AKLT systems

abstract:
  Affleck, Kennedy, Lieb and Taski (AKLT) constructed an exemplary spin-3/2
valence-bond solid (VBS) state on the hexagonal lattice, which is the ground
state of an isotropic quantum antiferromagnet and possesses no spontaneous
magnetization but finite correlation length. This is distinct from the N\'eel
ordered state of the spin-3/2 Heisenberg model on the same lattice. Niggemann,
Kl\"umper and Zittartz then generalized the AKLT Hamiltonian to one family
invariant under spin rotation about the z-axis. The ground states of this
family can be parameterized by a single parameter that deforms the AKLT state,
and this system exhibits a quantum phase transition between the VBS and N\'eel
phases, as the parameter increases from the AKLT point to large anisotropy. We
investigate the opposite regime when the parameter decreases from the AKLT
point and find that there appears to be a Berezinskii-Kosterlitz-Thouless-like
transition from the VBS phase to an XY phase. Such a transition also occurs in
the deformation of other types of AKLT states with triplet-bond constructions
on the same lattice. However, we do not find such an XY-like phase in the
deformed AKLT models on other trivalent lattices, such as square-octagon, cross
and star lattices. On the star lattice, the deformed family of AKLT states
remain in the same phase as the isotropic AKLT state throughout the whole
region of the parameter. However, for two triplet-bond generalizations, the
triplet VBS phase is sandwiched between two ferromagnetic phases (for large and
small deformation parameters, respectively), which are characterized by
spontaneous magnetizations along different axes. Along the way, we also discuss
how various deformed AKLT states can be used for the purpose of universal
quantum computation.


title:
Enhanced Superconducting Transition Temperature due to Tetragonal
  Domains in Two-Dimensionally Doped SrTiO$_3$

abstract:
  Strontium titanate is a low-temperature, non-Bardeen-Cooper-Schrieffer
superconductor that superconducts to carrier concentrations lower than in any
other system and exhibits avoided ferroelectricity at low temperatures. Neither
the mechanism of superconductivity in strontium titanate nor the importance of
the structure and dielectric properties for the superconductivity are well
understood. We studied the effects of twin structure on superconductivity in a
5.5-nm-thick layer of niobium-doped SrTiO$_{3}$ embedded in undoped
SrTiO$_{3}$. We used a scanning superconducting quantum interference device
susceptometer to image the local diamagnetic response of the sample as a
function of temperature. We observed regions that exhibited a superconducting
transition temperature $T_{c}$ $\gtrsim$ 10% higher than the temperature at
which the sample was fully superconducting. The pattern of these regions varied
spatially in a manner characteristic of structural twin domains. Our results
emphasize that the anisotropic dielectric properties of SrTiO$_{3}$ are
important for its superconductivity, and need to be considered in any theory of
the mechanism of the superconductivity.


title:
Quantum criticality in the two-dimensional dissipative quantum XY
  model-II

abstract:
  Earlier Monte-Carlo calculations on the dissipative two-dimensional XY model
are extended in several directions. We study the phase diagram and the
correlation functions when dissipation is very small, where it has properties
of the classical 3D-XY transition, i.e. one with a dynamical critical exponent
$z=1$. The transition changes from $z=1$ to the class of criticality with $z
\to \infty$ driven by topological defects, discovered earlier, beyond a
critical dissipation. We also find that the critical correlations have
power-law singularities as a function of tuning the ratio of the kinetic energy
to the potential energy for fixed large dissipation, as opposed to essential
singularities on tuning dissipation keeping the former fixed. A phase with
temporal disorder but spatial order of the Kosterlitz-Thouless form is also
further investigated. We also present results for the transition when the
allowed Caldeira-Leggett form of dissipation and the allowed form of
dissipation coupling to the compact rotor variables are both included. The
nature of the transition is then determined by the Caldeira-Leggett form.


title:
Gravitational wave transient signal emission via Ekman pumping in
  neutron stars during post-glitch relaxation phase

abstract:
  Glitches in the rotational frequency of a spinning neutron star could be
promising sources of gravitational wave signals lasting between a few
microseconds to a few weeks. The emitted signals and their properties depend
upon the internal properties of the neutron star. In neutron stars, the most
important physical properties of the fluid core are the viscosity of the fluid,
the stratification of flow in the equilibrium state and the adiabatic sound
speed. Such models were previously studied by van Eysden and Melatos [73] and
Bennett et al. [26] following simple assumptions on all contributing factors,
in which the post-glitch relaxation phase could be driven by the well-known
process of Ekman pumping [76, 17]. We explore the hydrodynamic properties of
the flow of fluid during this phase following more relaxed assumptions on the
stratification of flow and the pressure-density gradients within the neutron
star than previously studied. We calculate the time-scales of duration as well
as the amplitudes of the resulting gravitational wave signals, and we detail
their dependence on the physical properties of the fluid core. We find that it
is possible for the neutron star to emit gravitational wave signals in a wide
range of decay time-scales and within the detection sensitivity of aLIGO for
selected domains of physical parameters.


title: Explicit local multiplicative convolution of l-adic sheaves

abstract:
  We give explicit formulas for the local multiplicative convolution functors
which express the local monodromies of the convolution of two $\ell$-adic
sheaves on the torus ${\mathbb G}_m$ over the algebraic closure of a finite
field in terms of the local monodromies of the factors.


title:
Calculating vibrational spectra of molecules using tensor train
  decomposition

abstract:
  We propose a new algorithm for calculation of vibrational spectra of
molecules using tensor train decomposition. Under the assumption that
eigenfunctions lie on a low-parametric manifold of low-rank tensors we suggest
using well-known iterative methods that utilize matrix inversion (LOBPCG,
inverse iteration) and solve corresponding linear systems inexactly along this
manifold. As an application, we accurately compute vibrational spectra (84
states) of acetonitrile molecule CH$_3$CN on a laptop in one hour using only
$100$ MB of memory to represent all computed eigenfunctions.


title:
Accelerated ab-initio Molecular Dynamics: probing the weak dispersive
  forces in dense liquid hydrogen

abstract:
  We propose an ab-initio molecular dynamics method, capable to reduce
dramatically the autocorrelation time required for the simulation of classical
and quantum particles at finite temperature. The method is based on an
efficient implementation of a first order
  Langevin dynamics modified by means of a suitable, position dependent
acceleration matrix $S$. Here we apply this technique, within a Quantum Monte
Carlo (QMC) based wavefuntion approach and within the Born-Oppheneimer
approximation, for determining the phase diagram of high-pressure Hydrogen with
simulations much longer than the autocorrelation time. With the proposed
method, we are able to equilibrate in few hundreds steps even close to the
liquid-liquid phase transition (LLT).
  Within our approach we find that the LLT transition is consistent with recent
density functionals predicting a much larger transition pressures when the long
range dispersive forces are taken into account.

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


title: Tensor Squeezed Limits and the Higuchi Bound

abstract:
  We point out that tensor consistency relations-i.e. the behavior of
primordial correlation functions in the limit a tensor mode has a small
momentum-are more universal than scalar consistency relations. They hold in the
presence of multiple scalar fields and as long as anisotropies are diluted
exponentially fast. When de Sitter isometries are approximately respected
during inflation this is guaranteed by the Higuchi bound, which forbids the
existence of light particles with spin: De Sitter space can support scalar hair
but no curly hair. We discuss two indirect ways to look for the violation of
tensor con- sistency relations in observations, as a signature of models in
which inflation is not a strong isotropic attractor, such as solid inflation:
(a) Graviton exchange contribution to the scalar four-point function; (b)
Quadrupolar anisotropy of the scalar power spectrum due to super-horizon tensor
modes. This anisotropy has a well-defined statistics which can be distinguished
from cases in which the background has a privileged direction.


title:
Form Invariance, Topological Fluctuations and Mass Gap of Yang-Mills
  Theory

abstract:
  In order to have a new perspective on the long-standing problem of the mass
gap in Yang-Mills theory, we study the quantum Yang-Mills theory in the
presence of topologically nontrivial backgrounds in this paper. The
topologically stable gauge fields are constrained by the form invariance
condition and the topological properties. Obeying these constraints, the known
classical solutions to the Yang-Mills equation in the 3- and 4-dimensional
Euclidean spaces are recovered, and the other allowed configurations form the
nontrivial topological fluctuations at quantum level. Together, they constitute
the background configurations, upon which the quantum Yang-Mills theory can be
constructed. We demonstrate that the theory mimics the Higgs mechanism in a
certain limit and develops a mass gap at semi-classical level on a flat space
with finite size or on a sphere.


title:
Intergranular stress distributions in polycrystalline aggregates of
  irradiated stainless steel

abstract:
  In order to predict InterGranular Stress Corrosion Cracking (IGSCC) of
post-irradiated austenitic stainless steel in Light Water Reactor (LWR)
environment, reliable predictions of intergranular stresses are required.
Finite elements simulations have been performed on realistic polycrystalline
aggregate with a recently proposed physically-based crystal plasticity
constitutive equations validated for neutron-irradiated austenitic stainless
steel. Intergranular normal stress probability density functions are found with
respect to plastic strain and irradiation level, for uniaxial loading
conditions. In addition, plastic slip activity jumps at grain boundaries are
also presented. Intergranular normal stress distributions describe, from a
statistical point of view, the potential increase of intergranular stress with
respect to the macroscopic stress due to grain-grain interactions. The
distributions are shown to be well described by a master curve once rescaled by
the macroscopic stress, in the range of irradiation level and strain considered
in this study. The upper tail of this master curve is shown to be insensitive
to free surface effect, which is relevant for IGSCC


title: Performance Enhancement of the Golden Code by Utilizing ORIOL Antenna

abstract:
  In this paper, a novel method is exposed to improve the performance of the
Golden code, by using octagonal reconfigurable isolated orthogonal element
(ORIOL) antennas, instead of a conventional microstrip patch antenna. The
aforementioned antenna, should be employed in both the transmitter and the
receiver sides, to approach the mentioned improvement. As a matter fact, in
this paper, we recommend space-time-polarization diversity instead of
space-time singly; therefore it is obvious that by employing the aforementioned
technique, the system obtains more strength against destructive fading. The
simulations for different rates have confirmed that, utilizing ORIOL antenna
outperforms patch microstrip one, which is roughly about $2$ to $3$ dB,
according to the rates.


title:
Matter in the beam: Weak lensing, substructures and the temperature of
  dark matter

abstract:
  Warm Dark Matter (WDM) models offer an attractive alternative to the current
Cold Dark Matter (CDM) cosmological model. We present a novel method to
differentiate between WDM and CDM cosmologies, namely using weak lensing; this
provides a unique probe as it is sensitive to all the "matter in the beam", not
just dark matter haloes and the galaxies that reside in them, but also the
diffuse material between haloes. We compare the weak lensing maps of CDM
clusters to those in a WDM model corresponding to a thermally produced
$0.5$~keV dark matter particle. Our analysis clearly shows that the weak
lensing magnification, convergence and shear distributions can be used to
distinguish between CDM and WDM models. WDM models {\em increase} the
probability of weak magnifications, with the differences being significant to
$\gtrsim5\sigma$, while leaving no significant imprint on the shear
distribution. WDM clusters analysed in this work are more homogeneous than CDM
ones, and the fractional decrease in the amount of material in haloes is
proportional to the average increase in the magnification. This difference
arises from matter that would be bound in compact haloes in CDM being smoothly
distributed over much larger volumes at lower densities in WDM. Moreover, the
signature does not solely lie in the probability distribution function but in
the full spatial distribution of the convergence field.


title: Interaction between point charges, dipoles and graphene layers

abstract:
  We analyse the interaction between charges and graphene layers. The electric
polarisability of graphene induces a force, that can be described by an image
charge. The analysis shows that graphene can be described as an imperfect
conductor with a finite dielectric constant, $\epsilon_r$, for weak coupling,
and it behaves as a metal for strong fields. As a consequence, the interaction
between polar molecules and graphene layer(s) tends to align the molecular
dipole along the direction normal to the graphene, and quantitative estimates
of the energy gain are given The strength of this interaction can be sufficient
to overcome thermal effects when the molecule is close to the layer, even at
room temperature. Hence, boundary effects play a significant role in
determining the structure of systems such as water confined in atomically
narrow van der Waals heterostructures.


title:
Supporting the search for the CEP location with nonlocal PNJL models
  constrained by Lattice QCD

abstract:
  We investigate the possible location of the critical endpoint in the QCD
phase diagram based on nonlocal covariant PNJL models including a vector
interaction channel. The form factors of the covariant interaction are
constrained by lattice QCD data for the quark propagator. The comparison of our
results for the pressure including the pion contribution and the scaled
pressure shift $\Delta P / T^4$ vs $T/T_c$ with lattice QCD results shows a
better agreement when Lorentzian formfactors for the nonlocal interactions and
the wave function renormalization are considered. The strength of the vector
coupling is used as a free parameter which influences results at finite
baryochemical potential. It is used to adjust the slope of the pseudocritical
temperature of the chiral phase transition at low baryochemical potential and
the scaled pressure shift accessible in lattice QCD simulations. Our study,
albeit presently performed at the meanfield level, supports the very existence
of a critical point and favors its location within a region that is accessible
in experiments at the NICA accelerator complex.


title: The Polynomial Form of the Scattering Equations is an H-Basis

abstract:
  We prove that the polynomial form of the scattering equations is a Macaulay
H-basis. We demonstrate that this H-basis facilitates integrand reduction and
global residue computations in a way very similar to using a Gr\"obner basis,
but circumvents the heavy computation of the latter. As an example, we apply
the H-basis to prove the conjecture that the dual basis of the polynomial
scattering equations must contain one constant term.


title: A model for dislocations in epitaxially strained elastic films

abstract:
  A variational model for epitaxially strained films accounting for the
presence of dislocations is considered. Existence, regularity and some
qualitative properties of solutions are addressed.


title: Non-Abelian Vortex in Four Dimensions as a Critical String on a Conifold

abstract:
  Non-Abelian vortex strings supported in a certain four-dimensional N=2
Yang-Mills theory with fundamental matter were shown arXiv:1502.00683 to become
critical superstrings. In addition to translational moduli non-Abelian string
under consideration carries orientational and size moduli. Their dynamics is
described by two-dimensional sigma model whose target space is a tautological
bundle over the complex projective space. For the N=2 theory with the $U(2)$
gauge group and four fundamental hypermultiplets there are six orientational
and size moduli. After combining with four translational moduli they form a
ten-dimensional target space required for a superstring to be critical. For the
theory in question the target space of the sigma model is C^2 x Y_6, where Y_6
is a conifold. We study closed string states which emerge in four dimensions
(4D) and identify them with hadrons of the 4D bulk N=2 theory. It turns out
that most of the states arising from the ten-dimensional graviton spectrum are
non-dynamical in 4D. We find a single dynamical massless hypermultiplet
associated with the deformation of the complex structure of the conifold. We
interpret this degree of freedom as a monopole-monopole baryon of the 4D theory
(at strong coupling).


title:
Stable decompositions of certain representations of the finite general
  linear groups

abstract:
  We prove that the irreducible decomposition of the permutation representation
of GL(n,q) on GL(n,q)/GL(n-m,q) stabilizes for large n. We deduce, as a
consequence, a representation stability theorem for finitely generated
VIC-modules.


title: On relative $K$-motives, weights for them, and negative $K$-groups

abstract:
  We study certain triangulated categories of $K$-motives $DK(-)$ over a wide
class of base schemes, and define certain "weights" for them. We relate the
weights of particular $K$-motives to (negative) homotopy invariant $K$-groups
(tensored by $\mathbb{Z}[S^{-1}]$ for $S$ being the set of "non-invertible
primes") $\mathcal{K}_*(-)$. Our results yield a (new) result on the vanishing
of $\mathcal{K}_i(-)$ and of relative $\mathcal{K}$-groups for $i$ being "too
negative"; this statement is closely related to a question of Ch. Weibel. We
also prove that $\mathcal{K}_i(-)$ for $i<0$ is "supported in codimension
$-i$". Moreover, we establish several criteria for bounding (below) the weights
of $f_*(1_Y)$ ($1_Y$ is the tensor unit in $DK(Y)$); this automatically implies
the vanishing of the corresponding $E_2$-terms of Chow-weight spectral
sequences (and of the factors of the corresponding Chow-weight filtrations) for
any (co)homology of these motives. Our methods of bounding weights can be
applied to various "motivic" triangulated categories; this yields some new
statements on (constructible) complexes of \'etale sheaves.
  We also relate the weights of $K$-motives with rational coefficients to that
of Beilinson motives; the Chow-weight spectral sequences converging to their
$\mathbb{Q}_l$-\'etale (co)homology yield Deligne-type weights for the latter.
Somewhat surprisingly, we are able to prove in certain ("extreme") cases that
the corresponding weight bounds coming from \'etale (co)homology are precise.
We illustrate these statements by simple examples.


title: Weak lensing by galaxy troughs with modified gravity

abstract:
  We study the imprints that theories of gravity beyond GR can leave on the
lensing signal around line of sight directions that are predominantly
halo-underdense (called troughs) and halo-overdense. To carry out our
investigations, we consider the normal branch of DGP gravity, as well as a
phenomenological variant thereof that directly modifies the lensing potential.
The predictions of these models are obtained with N-body simulation and
ray-tracing methods using the ECOSMOG and Ray-Ramses codes. We analyse the
stacked lensing convergence profiles around the underdense and overdense lines
of sight, which exhibit, respectively, a suppression and a boost w.r.t. the
mean in the field of view. The modifications to gravity in these models
strengthen the signal w.r.t. $\Lambda{\rm CDM}$ in a scale-independent way. We
find that the size of this effect is the same for both underdense and overdense
lines of sight, which implies that the density field along the overdense
directions on the sky is not sufficiently evolved to trigger the suppression
effects of the screening mechanism. These results are robust to variations in
the minimum halo mass and redshift ranges used to identify the lines of sight,
as well as to different line of sight aperture sizes and criteria for their
underdensity and overdensity thresholds.


title:
The influence of circumnuclear environment on the radio emission from
  TDE jets

abstract:
  Dozens of stellar tidal disruption events (TDEs) have been identified at
optical, UV and X-ray wavelengths. A small fraction of these, most notably
Swift J1644+57, produce radio synchrotron emission, consistent with a powerful,
relativistic jet shocking the surrounding circumnuclear gas. The dearth of
similar non-thermal radio emission in the majority of TDEs may imply that
powerful jet formation is intrinsically rare, or that the conditions in
galactic nuclei are typically unfavorable for producing a detectable signal.
Here we explore the latter possibility by constraining the radial profile of
the gas density encountered by a TDE jet using a one-dimensional model for the
circumnuclear medium which includes mass and energy input from a stellar
population. Near the jet Sedov radius of 10$^{18}$ cm, we find gas densities in
the range of $n_{18} \sim$ 0.1$-$1000 cm$^{-3}$ across a wide range of
plausible star formation histories. Using one- and two-dimensional relativistic
hydrodynamical simulations, we calculate the synchrotron radio light curves of
TDE jets (as viewed both on and off-axis) across the allowed range of density
profiles. We find that bright radio emission would be produced across the
plausible range of nuclear gas densities by jets as powerful as Swift J1644+57,
and we quantify the relationship between the radio luminosity and jet energy.
We use existing radio detections and upper limits to constrain the energy
distribution of TDE jets. Radio follow up observations several months to
several years after the TDE candidate will strongly constrain the energetics of
any relativistic flow.


title:
Massive stars reveal variations of the stellar initial mass function in
  the Milky Way stellar clusters

abstract:
  We investigate whether the stellar initial mass function (IMF) is universal,
or whether it varies significantly among young stellar clusters in the Milky
Way. We propose a method to uncover the range of variation of the parameters
that describe the shape of the IMF for the population of young Galactic
clusters. These parameters are the slopes in the low and high stellar mass
regimes, $\gamma$ and $\Gamma$, respectively, and the characteristic mass,
$M_{ch}$. The method relies exclusively on the high mass content of the
clusters, but is able to yield information on the distributions of parameters
that describe the IMF over the entire stellar mass range. This is achieved by
comparing the fractions of single and lonely massive O stars in a recent
catalog of the Milky Way clusters with a library of simulated clusters built
with various distribution functions of the IMF parameters. The synthetic
clusters are corrected for the effects of the binary population, stellar
evolution, sample incompleteness, and ejected O stars. Our findings indicate
that broad distributions of the IMF parameters are required in order to
reproduce the fractions of single and lonely O stars in Galactic clusters. They
also do not lend support to the existence of a cluster mass-maximum stellar
mass relation. We propose a probabilistic formulation of the IMF whereby the
parameters of the IMF are described by Gaussian distribution functions centered
around $\gamma=0.91$, $\Gamma=1.37$, and $M_{ch}=0.41$ M$_{\odot}$, and with
dispersions of $\sigma_{\gamma}=0.25$, $\sigma_{\Gamma}=0.60$, and
$\sigma_{M_{ch}}=0.27$ M$_{\odot}$ around these values.


title:
Lensing Bias to CMB Measurements of Compensated Isocurvature
  Perturbations

abstract:
  Compensated isocurvature perturbations (CIPs) are modes in which the baryon
and dark matter density fluctuations cancel. They arise in the curvaton
scenario as well as some models of baryogenesis. While they leave no observable
effects on the cosmic microwave background (CMB) at linear order, they do
spatially modulate two-point CMB statistics and can be reconstructed in a
manner similar to gravitational lensing. Due to the similarity between the
effects of CMB lensing and CIPs, lensing contributes nearly Gaussian random
noise to the CIP estimator that approximately doubles the reconstruction noise
power. Additionally, the cross correlation between lensing and the integrated
Sachs-Wolfe (ISW) effect generates a correlation between the CIP estimator and
the temperature field even in the absence of a correlated CIP signal. For
cosmic-variance limited temperature measurements out to multipoles $l \leq
2500$, subtracting a fixed lensing bias degrades the detection threshold for
CIPs by a factor of $1.3$, whether or not they are correlated with the
adiabatic mode.


title:
The Hawking cascades of gravitons from higher-dimensional Schwarzschild
  black holes

abstract:
  It has recently been shown that the Hawking evaporation process of
$(3+1)$-dimensional Schwarzschild black holes is characterized by the
dimensionless ratio $\eta\equiv\tau_{\text{gap}}/\tau_{\text{emission}}\gg1$,
where $\tau_{\text{gap}}$ is the characteristic time gap between the emissions
of successive Hawking quanta and $\tau_{\text{emission}}$ is the characteristic
timescale required for an individual Hawking quantum to be emitted from the
Schwarzschild black hole. This strong inequality implies that the Hawking
cascade of gravitons from a $(3+1)$-dimensional Schwarzschild black hole is
extremely {\it sparse}. In the present paper we explore the semi-classical
Hawking evaporation rates of {\it higher}-dimensional Schwarzschild black
holes. We find that the dimensionless ratio
$\eta(D)\equiv{{\tau_{\text{gap}}}/{\tau_{\text{emission}}}}$, which
characterizes the Hawking emission of gravitons from the $(D+1)$-dimensional
Schwarzschild black holes, is a {\it decreasing} function of the spacetime
dimension. In particular, we show that higher-dimensional Schwarzschild black
holes with $D\gtrsim 10$ are characterized by the relation $\eta(D)<1$. Our
results thus imply that, contrary to the $(3+1)$-dimensional case, the
characteristic Hawking cascades of gravitons from these higher-dimensional
black holes have a {\it continuous} character.


title:
Approximate Bayesian estimation in large coloured graphical Gaussian
  models

abstract:
  Distributed estimation methods have recently been used to compute the maximum
likelihood estimate of the precision matrix for large graphical Gaussian
models. Our aim, in this paper, is to give a Bayesian estimate of the precision
matrix for large graphical Gaussian models with, additionally, symmetry
constraints imposed by an underlying graph which is coloured. We take the
sample posterior mean of the precision matrix as our estimate. We study its
asymptotic behaviour under the regular asymptotic regime when the number of
variables p is fixed and under the double asymptotic regime when both p and n
grow to infinity. We show in particular, that when the number of parameters of
the local models is uniformly bounded, the standard convergence rate we obtain
for the asymptotic consistency, in the Frobenius norm, of our estimate of the
precision matrix compares well with the rates in the current literature for the
maximum likelihood estimate.


title: Dark Matter and the Higgs in Natural SUSY

abstract:
  Null results from dark matter (DM) direct detection experiments and the 125
GeV Higgs both pose serious challenges to minimal supersymmetry. In this paper,
we propose a simple extension of the MSSM that economically solves both
problems: a "dark sector" consisting of a singlet and a pair of $SU(2)$
doublets. Loops of the dark sector fields help lift the Higgs mass to 125 GeV
consistent with naturalness, while the lightest fermion in the dark sector can
be viable thermal relic DM, provided that it is mostly singlet. The DM relic
abundance is controlled by s-wave annihilation to tops and Higgsinos, leading
to a tight relation between the relic abundance and the spin-dependent direct
detection cross section. As a result, the model will be fully probed by the
next generation of direct detection experiments. Finally we discuss the
discovery potential at LHC Run II.


title: Dark Matter Superfluidity

abstract:
  In this talk I summarize a novel framework that unifies the stunning success
of MOND on galactic scales with the triumph of the $\Lambda$CDM model on
cosmological scales. This is achieved through the rich and well-studied physics
of superfluidity. The dark matter and MOND components have a common origin,
representing different phases of a single underlying substance. In galaxies,
dark matter thermalizes and condenses to form a superfluid phase. The
superfluid phonons couple to baryonic matter particles and mediate a MOND-like
force. This framework naturally distinguishes between galaxies (where MOND is
successful) and galaxy clusters (where MOND is not): dark matter has a higher
temperature in clusters, and hence is in a mixture of superfluid and normal
phase. The rich and well-studied physics of superfluidity leads to a number of
striking observational signatures, which we briefly discuss. Remarkably the
critical temperature and equation of state of the dark matter superfluid are
similar to those of known cold atom systems. Identifying a precise cold atom
analogue would give important insights on the microphysical interactions
underlying DM superfluidity. Tantalizingly, it might open the possibility of
simulating the properties and dynamics of galaxies in laboratory experiments.


title:
High precision measurement of the Dzyaloshinsky-Moriya interaction
  between two rare-earth ions in a solid

abstract:
  We report on a direct measurement of the pair-wise anti-symmetric exchange
interaction, known as the Dzyaloshinsky-Moriya interaction (DMI), in a
Nd3+-doped YVO4 crystal. To this end we introduce a broadband electron spin
resonance technique coupled with an optical detection scheme which selectively
detects only one Nd3+-Nd3+ pair. Using this technique we can fully determine
the spin-spin coupling tensor, allowing us to experimentally determine both the
strength and direction of the DMI vector. We believe that this ability to fully
determine the interaction Hamiltonian is of interest for studying the numerous
magnetic phenomena where the DMI interaction is of fundamental importance,
including multiferroics. We also detect a singlet-triplet transition within the
pair, with a highly suppressed magnetic-field dependence, which suggests that
such systems could form singlet-triplet qubits with long coherence times for
quantum information applications.


title: Chern numbers and chiral anomalies in Weyl butterflies

abstract:
  The Hofstadter butterfly of lattice electrons in a strong magnetic field is a
cornerstone of condensed matter physics, exploring the competition between
periodicities imposed by the lattice and the field. In this work we introduce
and characterize the Weyl butterfly, which emerges when a large magnetic field
is applied to a three-dimensional Weyl semimetal. Using an experimentally
motivated lattice model for cold atomic systems, we solve this problem
numerically. We find that Weyl nodes reemerge at commensurate fluxes and
propose using wavepackets dynamics to reveal their chirality and location.
Moreover, we show that the chiral anomaly -- a hallmark of the topological Weyl
semimetal -- does not remain proportional to magnetic field at large fields,
but rather inherits a fractal structure of linear regimes as a function of
external field. The slope of each linear regime is determined by the difference
of two Chern numbers in gaps of the Weyl butterfly and can be measured
experimentally in time of flight.


title: Topological Speedups

abstract:
  Given a dynamical system $(X,T)$ one can define a speedup of $(X,T)$ as
another dynamical system conjugate to $S:X\rightarrow X$ where
$S(x)=T^{p(x)}(x)$ for some function $p:X\rightarrow\mathbb{Z}^{+}$. In $1985$
Arnoux, Ornstein, and Weiss showed that any aperiodic, not necessarily ergodic,
measure preserving system is isomorphic to a speedup of any ergodic measure
preserving system. In this paper we study speedups in the topological category.
Specifically, we consider minimal homeomorphisms on Cantor spaces. Our main
theorem gives conditions on when one such system is a speedup of another.
Furthermore, the main theorem serves as a topological analogue of the Arnoux,
Ornstein, and Weiss speedup theorem, as well as a 'one-sided" orbit equivalence
theorem.


title: Operation of a semiconductor microcavity under electric excitation

abstract:
  We present a microscopic theory for the description of the bias-controlled
operation of an exciton-polariton-based heterostructure, in particular, the
polariton laser. Combining together the Poisson equations for the scalar
electric potential and Fermi quasi-energies of electrons and holes in a
semiconductor heterostructure, the Boltzmann equation for the incoherent
excitonic reservoir and the Gross-Pitaevskii equation for the exciton-polariton
mean field, we simulate the dynamics of the system minimising the number of
free parameters and for the first time build a theoretical threshold
characteristics: number of particles vs applied bias. This approach, which also
accounts for the nonlinear (exciton-exciton) interaction, particle lifetime,
and which can, in principle, account for any relaxation mechanisms for the
carriers of charge inside the heterostructure or polariton loss, allows to
completely describe modern experiments on polariton transport and model new
devices.


title: Energy-Efficient Algorithms

abstract:
  We initiate the systematic study of the energy complexity of algorithms (in
addition to time and space complexity) based on Landauer's Principle in
physics, which gives a lower bound on the amount of energy a system must
dissipate if it destroys information. We propose energy-aware variations of
three standard models of computation: circuit RAM, word RAM, and
transdichotomous RAM. On top of these models, we build familiar high-level
primitives such as control logic, memory allocation, and garbage collection
with zero energy complexity and only constant-factor overheads in space and
time complexity, enabling simple expression of energy-efficient algorithms. We
analyze several classic algorithms in our models and develop low-energy
variations: comparison sort, insertion sort, counting sort, breadth-first
search, Bellman-Ford, Floyd-Warshall, matrix all-pairs shortest paths, AVL
trees, binary heaps, and dynamic arrays. We explore the time/space/energy
trade-off and develop several general techniques for analyzing algorithms and
reducing their energy complexity. These results lay a theoretical foundation
for a new field of semi-reversible computing and provide a new framework for
the investigation of algorithms.


title: Large N Thirring Matter in Three Dimensions

abstract:
  In this paper we calculate properties of the three-dimensional system of N
species of fermions at zero temperature and finite chemical potential, with the
four-fermionic interaction of the Thirring type. We observe that this model
fits consistently into framework of the Landau Fermi liquid theory, and
possesses a non-trivial zeroth and first Landau parameters. Our result is
derived to all orders of the Thirring coupling constant and to the leading
order of the large-N expansion. In particular we solve for the exact
current-current correlation function, and show that it exhibits a singular
behavior at zero frequency and twice of the Fermi momentum.


title: The Implementation of Low-cost Urban Acoustic Monitoring Devices

abstract:
  The urban sound environment of New York City (NYC) can be, amongst other
things: loud, intrusive, exciting and dynamic. As indicated by the large
majority of noise complaints registered with the NYC 311 information/complaints
line, the urban sound environment has a profound effect on the quality of life
of the city's inhabitants. To monitor and ultimately understand these sonic
environments, a process of long-term acoustic measurement and analysis is
required. The traditional method of environmental acoustic monitoring utilizes
short term measurement periods using expensive equipment, setup and operated by
experienced and costly personnel. In this paper a different approach is
proposed to this application which implements a smart, low-cost, static,
acoustic sensing device based around consumer hardware. These devices can be
deployed in numerous and varied urban locations for long periods of time,
allowing for the collection of longitudinal urban acoustic data. The varied
environmental conditions of urban settings make for a challenge in gathering
calibrated sound pressure level data for prospective stakeholders. This paper
details the sensors' design, development and potential future applications,
with a focus on the calibration of the devices' Microelectromechanical systems
(MEMS) microphone in order to generate reliable decibel levels at the
type/class 2 level.


title:
Persistent current in a 2D Josephson junction array wrapped around a
  cylinder

abstract:
  We study persistent currents in a Josephson junction array wrapped around a
cylinder. The $T=0$ quantum statistical mechanics of the array is equivalent to
the statistical mechanics of a classical $xy$ spin system in 2+1 dimensions at
the effective temperature $T^{*}=\sqrt{2JU}$, with $J$ being the Josephson
energy of the junction and $U$ being the charging energy of the superconducting
island. It is investigated analytically and numerically on lattices containing
over one million sites. For weak disorder and $T^{*}\ll J$ the dependence of
the persistent current on disorder and $T^{*}$ computed numerically agrees
quantitatively with the analytical result derived within the spin-wave
approximation. The high-$T^{*}$ and/or strong-disorder behavior is dominated by
instantons corresponding to the vortex loops in 2+1 dimensions. The current
becomes destroyed completely at the quantum phase transition into the
Cooper-pair insulating phase.


title: The exact solution of a generalized Bose-Hubbard model

abstract:
  I present the exact solution of a family of fragmented Bose-Hubbard models
and represent the models as graphs in one-dimension, two-dimensions and
three-dimensions with the condensates in the vertices. The models are solved by
the algebraic Bethe ansatz method.

categories: cond-mat.quant-gas math-ph math.MP nlin.SI


title:
Solution of the Dirichlet problem for the equation $a\Delta u+b\cdot
  \nabla u=0$ by the Monte Carlo method

abstract:
  In this paper we study the Dirichlet problem corresponding to an open bounded
set $D\subset \mathbb{R}^{d}$ and the operator \begin{equation*}
A=\sum_{i=1}^{d}a\frac{\partial ^{2}}{\partial x_{i}^{2}}
+\sum_{i=1}^{d}b_{i}\frac{\partial }{\partial x_{i}}, \end{equation*} where
$a>0$ and $b\in \mathbb{R}^{d}$. We define a mean value property and prove that
a function $u$ has such property in $D$ if and only if $Au=0$ in $D$. Using
this characterization, and a drifted Brownian motion, we define a family of
random variables that converges almost surely and the limit is used to give an
explicit representation for the solutions to the Dirichlet problem, this
immediately implies the uniqueness. On the other hand, the existence of the
solution is proved imposing a regular condition on the boundary of $D$.


title: Linear dynamical neural population models through nonlinear embeddings

abstract:
  A body of recent work in modeling neural activity focuses on recovering
low-dimensional latent features that capture the statistical structure of
large-scale neural populations. Most such approaches have focused on linear
generative models, where inference is computationally tractable. Here, we
propose fLDS, a general class of nonlinear generative models that permits the
firing rate of each neuron to vary as an arbitrary smooth function of a latent,
linear dynamical state. This extra flexibility allows the model to capture a
richer set of neural variability than a purely linear model, but retains an
easily visualizable low-dimensional latent space. To fit this class of
non-conjugate models we propose a variational inference scheme, along with a
novel approximate posterior capable of capturing rich temporal correlations
across time. We show that our techniques permit inference in a wide class of
generative models.We also show in application to two neural datasets that,
compared to state-of-the-art neural population models, fLDS captures a much
larger proportion of neural variability with a small number of latent
dimensions, providing superior predictive performance and interpretability.


title:
Suppressing Background Radiation Using Poisson Principal Component
  Analysis

abstract:
  Performance of nuclear threat detection systems based on gamma-ray
spectrometry often strongly depends on the ability to identify the part of
measured signal that can be attributed to background radiation. We have
successfully applied a method based on Principal Component Analysis (PCA) to
obtain a compact null-space model of background spectra using PCA projection
residuals to derive a source detection score. We have shown the method's
utility in a threat detection system using mobile spectrometers in urban scenes
(Tandon et al 2012). While it is commonly assumed that measured photon counts
follow a Poisson process, standard PCA makes a Gaussian assumption about the
data distribution, which may be a poor approximation when photon counts are
low. This paper studies whether and in what conditions PCA with a Poisson-based
loss function (Poisson PCA) can outperform standard Gaussian PCA in modeling
background radiation to enable more sensitive and specific nuclear threat
detection.


title:
Dipole excitation of surface plasmon on a conducting sheet: finite
  element approximation and validation

abstract:
  We formulate and validate a finite element approach to the propagation of a
slowly decaying electromagnetic wave, called surface plasmon-polariton, excited
along a conducting sheet, e.g., a single-layer graphene sheet, by an electric
Hertzian dipole. By using a suitably rescaled form of time-harmonic Maxwell's
equations, we derive a variational formulation that enables a direct numerical
treatment of the associated class of boundary value problems by appropriate
curl-conforming finite elements. The conducting sheet is modeled as an
idealized hypersurface with an effective electric conductivity. The requisite
weak discontinuity for the tangential magnetic field across the hypersurface
can be incorporated naturally into the variational formulation. We carry out
numerical simulations for an infinite sheet with constant isotropic
conductivity embedded in two spatial dimensions; and validate our numerics
against the closed-form exact solution obtained by the Fourier transform in the
tangential coordinate. Numerical aspects of our treatment such as an absorbing
perfectly matched layer, as well as local refinement and a-posteriori error
control are discussed.


title: Towards theory of C-symmetries

abstract:
  The concept of C-symmetry originally appeared in PT-symmetric quantum
mechanics is studied within the Krein spaces framework.