title:
Electromagnetically Induced Distortion of a Fibrin Matrix with Embedded
  Microparticles

abstract:
  Blood clots occur in the human body when they are required to prevent
bleeding. In pathological states such as diabetes and sickle cell disease,
blood clots can also form undesirably due to hypercoagulable plasma conditions.
With the continued effort in developing fibrin therapies for potential
life-saving solutions, more mechanical modeling is needed to understand the
properties of fibrin structures with inclusions. In this study, a fibrin matrix
embedded with magnetic micro particles (MMPs) was subjected to a magnetic field
to determine the magnitude of the required force to create plastic deformation
within the fibrin clot. Using finite element (FE) analysis, we estimated the
magnetic force from an electromagnet at a sample space located approximately 3
cm away from the coil center. This electromagnetic force coupled with gravity
was applied on a fibrin mechanical system with MMPs to calculate the stresses
and displacements. Using appropriate coil parameters, it was determined that
application of a magnetic field of 730 A/m on the fibrin surface was necessary
to achieve an electromagnetic force of 36 nN (to engender plastic deformation).


title:
Field Induced Oscillation of Two Majorana Modes for a finite Quantum
  Wire

abstract:
  The evolution of quantum walk on a finite wire under a small increment of
vector potential $\alpha$ can exhibit intrinsic quantum oscillation of the two
topologically protected bound states corresponding to the Majorana modes. By
tuning an external electric field corresponding to the addition of an $\alpha$
impulse at the end of each intrinsic period, the intrinsic oscillation is
enveloped by a beat modulation with a longer period. This beat oscillation is
useful in the preparation of decoherence-free qubit in trapped ion chain and
may be observed in several experiments.


title: Energy dissipation and fluctuations in a driven liquid

abstract:
  Minimal models of active and driven particles have recently been used to
elucidate many properties non-equilibrium systems. However, the relation
between energy consumption and changes in the structure and transport
properties of these non-equilibrium materials remains to be explored. We
explore this relation in a minimal model of a driven liquid that settles into a
time periodic steady state. Using concepts from stochastic thermodynamics and
liquid state theories, we show how the work performed on the system by the
various non-conservative, time dependent forces - this quantifies a violation
of time reversal symmetry - modifies the structural, transport, and phase
transition properties of the driven liquid


title:
Dynamic mode locking in a driven colloidal system: experiments and
  theory

abstract:
  In this article we examine the dynamics of a colloidal particle driven by a
modulated force over a sinusoidal optical potential energy landscape. Coupling
between the competing frequencies of the modulated drive and that of particle
motion over the periodic landscape leads to synchronisation of particle motion
into discrete modes. This synchronisation manifests as steps in the average
particle velocity, with mode locked steps covering a range of average driving
velocities. The amplitude and frequency dependence of the steps are considered,
and compared to results from analytic theory, Langevin Dynamics simulations,
and Dynamic Density Functional Theory. Furthermore, the critical driving
velocity is studied, and simulation used to extend the range of conditions
accessible in experiments alone. Finally, state diagrams from experiment,
simulation, and theory are used to show the extent of the dynamically locked
modes in two dimensions, as a function of both the amplitude and frequency of
the modulated drive.


title: High temperature dynamics in quantum compass models

abstract:
  We analyze the high temperature spin dynamics of compass models using a
moment expansion. We point out that the evaluation of moments maps to the
enumeration of paths in a branching process on the lattice. This mapping to a
statistical mechanics combinatorics problem provides an elegant visualization
of the analysis. We present results for the time dependent spin correlation
function (which is of relevance to NMR experiments) for two compass models: the
Kitaev honeycomb model and two-dimensional compass model.


title:
Tomographic active optical trapping of arbitrarily shaped objects by
  exploiting 3-D refractive index maps

abstract:
  Optical trapping can be used to manipulate the three-dimensional (3-D) motion
of spherical particles based on the simple prediction of optical forces and the
responding motion of samples. However, controlling the 3-D behaviour of
non-spherical particles with arbitrary orientations is extremely challenging,
due to experimental difficulties and the extensive computations. Here, we
achieved the real-time optical control of arbitrarily shaped particles by
combining the wavefront shaping of a trapping beam and measurements of the 3-D
refractive index (RI) distribution of samples. Engineering the 3-D light field
distribution of a trapping beam based on the measured 3-D RI map of samples
generates a light mould, which can be used to manipulate colloidal and
biological samples which have arbitrary orientations and/or shapes. The present
method provides stable control of the orientation and assembly of arbitrarily
shaped particles without knowing a priori information about the sample
geometry. The proposed method can be directly applied in biophotonics and soft
matter physics.


title: Phase changes in delay propagation networks

abstract:
  The analysis of the dynamics of delays propagation is one of the major topics
inside Air Transport Management research. Delays are generated by the elements
of the system, but their propagation is a global process fostered by
relationships inside the network. If the topology of such propagation process
has been extensively studied in the literature, little attention has been
devoted to the fact that such topology may have a dynamical nature. Here we
differentiate between two phases of the system by applying two causality
metrics, respectively describing the standard phase (i.e. propagation of normal
delays) and a disrupted one (corresponding to abnormal and unexpected delays).
We identify the critical point triggering the change of the topology of the
system, in terms of delays magnitude, using a historical data set of flights
crossing Europe in 2011. We anticipate that the proposed results will open new
doors towards the understanding of the delay propagation dynamics and the
mitigation of extreme events.


title: Universal behavior for single-file diffusion on a disordered fractal

abstract:
  We study single-file diffusion on a one-dimensional lattice with a random
fractal distribution of hopping rates. For finite lattices, this problem shows
three clearly different regimes, namely, nearly independent particles, highly
interacting particles, and saturation. The mean-square displacement of a tagged
particle as a function of time follows a power law in each regime. The first
crossover time $t_s$, between the first and the second regime, depends on the
particle density. The other crossover time $t_l$, between the second and the
third regime, depends on the lattice length. We find analytic expressions for
these dependencies and show how the general behavior can be characterized by an
universal form. We also show that the mean-square displacement of the center of
mass presents two regimes; anomalous diffusion for times shorter than $t_l$,
and normal diffusion for times longer than $t_l$. We study single-file
diffusion on a one-dimensional lattice with a random fractal distribution of
hopping rates. For finite lattices, this problem shows three clearly different
regimes, namely, nearly independent particles, highly interacting particles,
and saturation. The mean-square displacement of a tagged particle as a function
of time follows a power law in each regime. The first crossover time $t_s$,
between the first and the second regime, depends on the particle density. The
other crossover time $t_l$, between the second and the third regime, depends on
the lattice length. We find analytic expressions for these dependencies and
show how the general behavior can be characterized by an universal form. We
also show that the mean-square displacement of the center of mass presents two
regimes; anomalous diffusion for times shorter than $t_l$, and normal diffusion
for times longer than $t_l$.


title:
Linear polarization study of microwave-radiation-induced
  magnetoresistance oscillations: Comparison of power dependence to theory

abstract:
  We present an experimental study of the microwave power and the linear
polarization angle dependence of the microwave-induced magnetoresistance
oscillations in the high-mobility GaAs/AlGaAs two-dimensional electron system.
Experimental results show the sinusoidal dependence of the oscillatory
magnetoresistance extrema as a function of the polarization angle. Yet, as the
microwave power increases, the angular dependence includes additional harmonic
content, and it begins to resemble the absolute value of the cosine function.
We present a theory to explain such peculiar behavior.


title: Topological insulator in a helicoidal magnetization field

abstract:
  A key feature of topological insulators is the robustness of the electron
energy spectrum. At a surface of a topological insulator, Dirac point is
protected by the characteristic symmetry of the system. The breaking of the
symmetry opens a gap in the energy spectrum. Therefore, topological insulators
are very sensitive to magnetic fields, which can open a gap in the electronic
spectrum. Concerning "internal" magnetic effects, for example the situation
with doped magnetic impurities, is not trivial. A single magnetic impurity is
not enough to open the band gap, while in the case of a ferromagnetic chain of
deposited magnetic impurities the Dirac point is lifted. However, a much more
interesting case is when localized magnetic impurities form a chiral spin
order. Our first principle density functional theory calculations have shown
that this is the case for Fe deposited on the surface of Bi2Se3 topological
insulator. But not only magnetic impurities can form a chiral helicoidal spin
texture. An alternative way is to use chiral multiferroics (prototype material
is LiCu2O2) that induce a proximity effect. The theoretical approach we present
here is valid for both cases. We observed that opposite to a ferromagnetically
ordered case, a chiral spin order does not destroy the Dirac point. We also
observed that the energy gap appears at the edges of the new Brillouin zone.
Another interesting result concerns the spin dynamics. We derived an equation
for the spin density dynamics with a spin current and relaxation terms. We have
shown that the motion of the conductance electron generates a magnetic torque
and exerts a certain force on the helicoidal texture.


title:
Swimming at small Reynolds number of a planar assembly of spheres in an
  incompressible viscous fluid with inertia

abstract:
  Translational and rotational swimming at small Reynolds number of a planar
assembly of identical spheres immersed in an incompressible viscous fluid is
studied on the basis of a set of equations of motion for the individual
spheres. The motion of the spheres is caused by actuating forces and forces
derived from a direct interaction potential, as well as hydrodynamic forces
exerted by the fluid as frictional and added mass hydrodynamic interactions.
The translational and rotational swimming velocities of the assembly are
deduced from momentum and angular momentum balance equations. The mean power
required during a period is calculated from an instantaneous power equation.
Expressions are derived for the mean swimming velocities and the power, valid
to second order in the amplitude of displacements from the relative equilibrium
positions. Hence these quantities can be evaluated for prescribed periodic
displacements. Explicit calculations are performed for three spheres
interacting such that they form an equilateral triangle in the rest
configuration.


title:
An introduction to associative geometry with applications to integrable
  systems

abstract:
  The aim of these notes is to provide a reasonably short and "hands-on"
introduction to the differential calculus on associative algebras over a field
of characteristic zero. Following a suggestion of Ginzburg's we call the
resulting theory associative geometry. We argue that this formalism sheds a new
light on some classic solution methods in the theory of finite-dimensional
integrable dynamical systems.


title:
Double-real corrections at O(alpha alpha_s) to single gauge boson
  production

abstract:
  We consider the O(alpha alpha_s) corrections to single on-shell gauge boson
production at hadron colliders. We concentrate on the contribution of all the
subprocesses where the gauge boson is accompanied by the emission of two
additional real partons and we evaluate the corresponding total cross sections.
The latter are divergent quantities, because of soft and collinear emissions,
and are expressed as Laurent series in the dimensional regularization
parameter. The total cross sections are evaluated by means of reverse
unitarity, i.e. expressing the phase-space integrals in terms of two-loop
forward box integrals with cuts on the final state particles. The results are
reduced to a combination of Master Integrals, which eventually are evaluated in
terms of Generalized Polylogarithms. The presence of internal massive lines in
the Feynman diagrams, due to the exchange of electroweak gauge bosons, causes
the appearance of 14 Master Integrals which were not previously known in the
literature and have been evaluated via Differential Equations.


title:
Spin-Orbit Dimers and Non-Collinear Phases in $d^1$ Cubic Double
  Perovskites

abstract:
  We formulate and study a spin-orbital model for a family of cubic double
perovskites with $d^1$ ions occupying a frustrated fcc sublattice. A
variational approach and a complimentary analytical analysis reveal a rich
variety of phases emerging from the interplay of Hund's and spin-orbit
couplings (SOC). The phase digram includes non-collinear ordered states, with
or without net moment, and, remarkably, a large window of a non-magnetic
disordered spin-orbit dimer phase. The present theory uncovers the physical
origin of the unusual amorphous valence bond state experimentally suggested for
Ba$_2B$MoO$_6$ ($B$=Y,Lu), and predicts possible ordered patterns in
Ba$_2B$OsO$_6$ ($B$=Na,Li) compounds.


title: Current-induced skyrmion generation and dynamics in symmetric bilayers

abstract:
  Magnetic skyrmions are textures behaving as quasiparticles which are
topologically different from other states. Their discovery in systems with
broken inversion symmetry sparked the search for materials containing such
magnetic phase at room temperature. Their topological properties combined with
the chirality-related spin-orbit torques make them interesting objects to
control the magnetization at nanoscale. Here we show that a pair of coupled
skyrmions with the same topological charge and opposite chiralities can be
stabilized in a symmetric magnetic bilayer system by combining
Dzyaloshinskii-Moriya interaction (DMI) and dipolar coupling effects. This
effect opens a new path for skyrmion stabilization with much lower DMI. We then
demonstrate in a single device with two different electrodes that such
skyrmions can be efficiently and independently written and shifted by electric
current at large velocities. The skyrmionic nature of the observed
quasiparticles is further confirmed by using the gyrotropic force as a
topological filter. These results set the ground for emerging spintronic
technologies where issues concerning skyrmion stability, nucleation, and
propagation are paramount.


title:
Optimised photonic crystal waveguide for chiral light-matter
  interactions

abstract:
  We present slow-light photonic crystal waveguide designs that provide a
$\times$8.6 improvement of the local density of optical states at a fully
chiral point over previous designs.


title:
Twistronics: Manipulating the Electronic Properties of Two-dimensional
  Layered Structures through their Twist Angle

abstract:
  The ability in experiments to control the relative twist angle between
successive layers in two-dimensional (2D) materials offers a new approach to
manipulating their electronic properties; we refer to this approach as
"twistronics". A major challenge to theory is that, for arbitrary twist angles,
the resulting structure involves incommensurate (aperiodic) 2D lattices. Here,
we present a general method for the calculation of the electronic density of
states of aperiodic 2D layered materials, using parameter-free hamiltonians
derived from ab initio density-functional theory. We use graphene, a semimetal,
and MoS$_2$, a representative of the transition metal dichalcogenide (TMDC)
family of 2D semiconductors, to illustrate the application of our method, which
enables fast and efficient simulation of multi-layered stacks in the presence
of local disorder and external fields. We comment on the interesting features
of their Density of States (DoS) as a function of twist-angle and local
configuration and on how these features can be experimentally observed.


title: Kardar-Parisi-Zhang Interfaces with Inward Growth

abstract:
  We study the $(1+1)$-dimensional Kardar-Parisi-Zhang (KPZ) interfaces growing
inward from ring-shaped initial conditions, experimentally and numerically,
using growth of a turbulent state in liquid-crystal electroconvection and an
off-lattice Eden model, respectively. To realize the ring initial condition
experimentally, we introduce a holography-based technique that allows us to
design the initial condition arbitrarily. Then, we find that fluctuation
properties of ingrowing circular interfaces are distinct from those for the
curved or circular KPZ subclass and, instead, are characterized by the flat
subclass. More precisely, we find an asymptotic approach to the Tracy-Widom
distribution for the Gaussian orthogonal ensemble and the $\text{Airy}_1$
spatial correlation, as long as time is much shorter than the characteristic
time determined by the initial curvature. Near this characteristic time,
deviation from the flat KPZ subclass is found, which can be explained in terms
of the correlation length and the circumference. Our results indicate that the
sign of the initial curvature has a crucial role in determining the universal
distribution and correlation functions of the KPZ class.


title: Simple and tight monogamy relations for a class of Bell inequalities

abstract:
  Physical principles constraints the way nonlocal correlations can be
distributed among distant parties in a Bell-type experiment. These constraints
are usually expressed by monogamy relations that bound the amount of Bell
inequality violation observed by a set of parties by the violation observed by
a different set of parties. Here we show that the no-signaling principle yields
a simple and tight monogamy relations for an important class of bipartite and
multipartite Bell inequalities. We also link these trade-offs to the guessing
probability--a key quantity in the device-independent information processing.


title: Computing JSJ decompositions of hyperbolic groups

abstract:
  We present an algorithm that computes Bowditch's canonical JSJ decomposition
of a given one-ended hyperbolic group over its virtually cyclic subgroups. The
algorithm works by identifying topological features in the boundary of the
group. As a corollary we also show how to compute the JSJ decomposition of such
a group over its virtually cyclic subgroups with infinite centre. We also give
a new algorithm that determines whether or not a given one-ended hyperbolic
group is virtually fuchsian. Our approach uses only the geometry of large balls
in the Cayley graph and avoids Makanin's algorithm.


title:
Convexity of power functions and bilinear embedding for divergence-form
  operators with complex coefficients

abstract:
  We introduce a condition on accretive matrix functions, called
$p$-ellipticity, and discuss its applications to the $L^p$ theory of elliptic
PDE with complex coefficients. Our examples are:
  (i) generalized convexity of power functions (Bellman functions),
  (ii) dimension-free bilinear embeddings,
  (iii) $L^p$-contractivity of semigroups and
  (iv) holomorphic functional calculus.
  Recent work by Dindo\v{s} and Pipher (arXiv:1612.01568v3) established close
ties between $p$-ellipticity and
  (v) regularity theory of elliptic PDE with complex coefficients.
  The $p$-ellipticity condition arises from studying uniform positivity of a
quadratic form associated with the matrix in question on one hand, and the
Hessian of a power function on the other. Our results regarding contractivity
extend earlier theorems by Cialdea and Maz'ya.


title: Weakly dynamic dark energy via metric-scalar couplings with torsion

abstract:
  We study the dynamical aspects of dark energy in the context of a
non-minimally coupled scalar field with curvature and torsion. Whereas the
scalar field acts as the source of the trace mode of torsion, a suitable
constraint on the torsion pseudo-trace provides a mass term for the scalar
field in the effective action. In the equivalent scalar-tensor framework, we
find explicit cosmological solutions representing dark energy in both Einstein
and Jordan frames. We demand the dynamical evolution of the dark energy to be
weak enough, so that the present-day values of the cosmological parameters
could be estimated keeping them within the confidence limits set for the
standard $\L$CDM model from recent observations. For such estimates, we examine
the variations of the effective matter density and the dark energy equation of
state parameters over different redshift ranges. In spite of being weakly
dynamic, the dark energy component differs significantly from the cosmological
constant, both in characteristics and features, for e.g. it interacts with the
cosmological (dust) fluid in the Einstein frame, and crosses the phantom
barrier in the Jordan frame. We also obtain the upper bounds on the torsion
mode parameters and the lower bound on the effective Brans-Dicke parameter. The
latter turns out to be fairly large, and in agreement with the local gravity
constraints, which therefore come in support of our analysis.


title:
Generation of high-field narrowband terahertz radiation by
  counterpropagating plasma wakes

abstract:
  It is found that nonlinear interaction of plasma wakefields driven by
counterpropagating laser or particle beams can efficiently generate high-power
electromagnetic radiation at the second harmonic of the plasma frequency. Using
a simple analytical theory and particle-in-cell simulations, we show that this
phenomenon can be attractive for producing high-field ($\sim 10$ MV/cm)
narrowband terahertz pulses with the gigawatt power level and millijoule energy
content.


title:
Distance Dependent Offsets between Parallaxes for Nearby Stars and Gaia
  DR1 Parallaxes

abstract:
  We use 612 single stars with previously published trigonometric parallaxes
placing them within 25 pc to evaluate parallaxes released in Gaia's first data
release (DR1). We find that the Gaia parallaxes are, on average, $0.24 \pm
0.02$ mas smaller than the weighted mean trigonometric parallax values for
these stars in the solar neighborhood. We also find that the offset changes
with distance out to 100 pc, in the sense that the closer the star, the larger
the offset. We find no systematic trends in the parallax offsets with stellar
$V$ magnitude, $V-K$ color, or proper motion. We do find that the offset is
roughly twice as large for stars south of the ecliptic compared to those that
are north.


title: Chimera-like States in Structured Heterogeneous Networks

abstract:
  Chimera-like states are manifested through the coexistence of synchronous and
asynchronous dynamics and have been observed in various systems. To analyze the
role of network topology in giving rise to chimera-like states we study a
heterogeneous network model comprising two group of nodes, of high and low
degrees of connectivity. The architecture facilitates the analysis of the
system, which separates into a densely-connected coherent group of nodes,
perturbed by their sparsely-connected drifting neighbors. It describes a
synchronous behavior of the densely-connected group and scaling properties of
the induced perturbations.


title:
Low-temperature interfaces: Prewetting, layering, faceting and
  Ferrari-Spohn diffusions

abstract:
  In this paper, we survey and discuss various surface phenomena such as
prewetting, layering and faceting for a family of two- and three-dimensional
low-temperature models of statistical mechanics, notably Ising models and
(2+1)-dimensional solid-on-solid (SOS) models, with a particular accent on
scaling regimes which lead or, in most cases, are conjectured to lead to
Ferrari-Spohn type diffusions.


title: Spin and topological order in a periodically driven spin chain

abstract:
  The periodically driven quantum Ising chain has recently attracted a large
attention in the context of Floquet engineering. In addition to the common
paramagnet and ferromagnet, this driven model can give rise to new topological
phases. In this work we systematically explore its quantum phase diagram, by
examining the properties of its Floquet ground state. We specifically focus on
driving protocols with time-reversal invariant points, and demonstrate the
existence of an infinite number of distinct phases. These phases are separated
by second-order quantum phase transitions, accompanied by continuous changes of
local and string order parameters, as well as sudden changes of a topological
winding number and of the number of protected edge states. When one of these
phase transitions is adiabatically crossed, the correlator associated to the
order parameter is nonvanishing over a length scale which shows a Kibble-Zurek
scaling. In some phases, the Floquet ground state spontaneously breaks the
discrete time-translation symmetry of the Hamiltonian. Our findings provide a
better understanding of topological phases in periodically driven clean
integrable models.


title: Dissipationless Hall Current in Dense Quark Matter in a Magnetic Field

abstract:
  We show the realization of axion electrodynamics within the Dual Chiral
Density Wave phase of dense quark matter in the presence of a magnetic field.
The system exhibits an anomalous dissipantionless Hall current perpendicular to
the magnetic field and an anomalous electric charge density. Connection to
topological insulators and 3D optical lattices, as well as possible
implications for heavy-ion collisions and neutron stars are outlined.


title:
Ab Initio Excited States from the In-Medium Similarity Renormalization
  Group

abstract:
  We present two new methods for performing ab initio calculations of excited
states for closed-shell systems within the in-medium similarity renormalization
group (IMSRG) framework. Both are based on combining the IMSRG with simple
many-body methods commonly used to target excited states, such as the
Tamm-Dancoff approximation (TDA) and equations-of-motion (EOM) techniques. In
the first approach, a two-step sequential IMSRG transformation is used to drive
the Hamiltonian to a form where a simple TDA calculation (i.e., diagonalization
in the space of $1$p$1$h excitations) becomes exact for a subset of
eigenvalues. In the second approach, equations-of-motion (EOM) techniques are
applied to the ground-state-decoupled IMSRG Hamiltonian to access excited
states. We perform proof-of-principle calculations for parabolic quantum dots
in two-dimensions and the closed shell nuclei $^{16}$O and $^{22}$O. We find
that the TDA-IMSRG approach gives better accuracy than the EOM-IMSRG when
calculations converge, but is otherwise lacking the versatility and numerical
stability of the latter. Our calculated spectra are in reasonable agreement
with analogous EOM-coupled-cluster (EOM-CC) calculations, which paves the way
for more interesting applications of the EOM-IMSRG to calculations of
consistently evolved observables such as electromagnetic strength functions and
nuclear matrix elements, and extensions to nuclei within 1-2 nucleons of a
closed shell by generalizing the EOM ladder operator to include particle-number
nonconserving terms.


title: Capelli elements of the group algebra

abstract:
  Inspired by the Capelli identities for group determinants obtained by T\^oru
Umeda, we give a basis of the center of the group algebra of any finite group
by using Capelli identities for irreducible representations.
  The Capelli identities for irreducible representations are modifications of
the Capelli identity. These identities lead to Capelli elements of the group
algebra. These elements construct a basis of the center of the group algebra.


title:
Time scale for adiabaticity breakdown in driven many-body systems and
  orthogonality catastrophe

abstract:
  The adiabatic theorem is a fundamental result established in the early days
of quantum mechanics, which states that a system can be kept arbitrarily close
to the instantaneous ground state of its Hamiltonian if the latter varies in
time slowly enough. The theorem has an impressive record of applications
ranging from foundations of quantum field theory to computational recipes in
molecular dynamics. In light of this success it is remarkable that a
practicable quantitative understanding of what "slowly enough" means is limited
to a modest set of systems mostly having a small Hilbert space. Here we show
how this gap can be bridged for a broad natural class of physical systems,
namely many-body systems where a small move in the parameter space induces an
orthogonality catastrophe. In this class, the conditions for adiabaticity are
derived from the scaling properties of the parameter dependent ground state
without a reference to the excitation spectrum. This finding constitutes a
major simplification of a complex problem, which otherwise requires solving
non-autonomous time evolution in a large Hilbert space. We illustrate our
general results by analyzing conditions for the transport quantization in a
topological Thouless pump.


title: Model Dynamics for Quantum Computing

abstract:
  A model master equation suitable for quantum computing dynamics is presented.
In an ideal quantum computer (QC), a system of qubits evolves in time unitarily
and, by virtue of their entanglement, interfere quantum mechanically to solve
otherwise intractable problems. In the real situation, a QC is subject to
decoherence and attenuation effects due to interaction with an environment and
with possible short-term random disturbances and gate deficiencies. The
stability of a QC under such attacks is a key issue for the development of
realistic devices. We assume that the influence of the environment can be
incorporated by a master equation that includes unitary evolution with gates,
supplemented by a Lindblad term. Lindblad operators of various types are
explored; namely, steady, pulsed, gate friction, and measurement operators. In
the master equation, we use the Lindblad term to describe short time intrusions
by random Lindblad pulses. The phenomenological master equation is then
extended to include a nonlinear Beretta term that describes the evolution of a
closed system with increasing entropy, plus a Bath environment term stipulated
by a fixed temperature. Here we explore the case of a simple one-qubit system
in preparation for generalization to multi-qubit, qutrit and hybrid
qubit-qutrit systems. This model master equation can be used to test the
stability of memory and the efficacy of quantum gates. The properties of such
hybrid master equations are explored, with emphasis on the role of thermal
equilibrium and entropy constraints.


title: Combinatorial Prophet Inequalities

abstract:
  We introduce a novel framework of Prophet Inequalities for combinatorial
valuation functions. For a (non-monotone) submodular objective function over an
arbitrary matroid feasibility constraint, we give an $O(1)$-competitive
algorithm. For a monotone subadditive objective function over an arbitrary
downward-closed feasibility constraint, we give an $O(\log n \log^2
r)$-competitive algorithm (where $r$ is the cardinality of the largest feasible
subset).
  Inspired by the proof of our subadditive prophet inequality, we also obtain
an $O(\log n \cdot \log^2 r)$-competitive algorithm for the Secretary Problem
with a monotone subadditive objective function subject to an arbitrary
downward-closed feasibility constraint. Even for the special case of a
cardinality feasibility constraint, our algorithm circumvents an
$\Omega(\sqrt{n})$ lower bound by Bateni, Hajiaghayi, and Zadimoghaddam
\cite{BHZ13-submodular-secretary_original} in a restricted query model.
  En route to our submodular prophet inequality, we prove a technical result of
independent interest: we show a variant of the Correlation Gap Lemma for
non-monotone submodular functions.


title:
On the role of extrinsic noise in microRNA-mediated bimodal gene
  expression

abstract:
  Several studies highlighted the relevance of extrinsic noise in shaping cell
decision making and differentiation in molecular networks. Experimental
evidences of phenotypic differentiation are given by the presence of bimodal
distributions of gene expression levels, where the modes of the distribution
often correspond to different physiological states of the system. We
theoretically address the presence of bimodal phenotypes in the context of
microRNA (miRNA)-mediated regulation. MiRNAs are small noncoding RNA molecules
that downregulate the expression of their target mRNAs. The nature of this
interaction is titrative and induces a threshold effect: below a given target
transcription rate no mRNAs are free and available for translation. We
investigate the effect of extrinsic noise on the system by introducing a
fluctuating miRNA-transcription rate. We find that the presence of extrinsic
noise favours the presence of bimodal target distributions which can be
observed for a wider range of parameters compared to the case with intrinsic
noise only and for lower miRNA-target interaction strength. Our results suggest
that combining threshold-inducing interactions with extrinsic noise provides a
simple and robust mechanism for obtaining bimodal populations not requiring
fine tuning. We furthermore characterise the protein distributions dependence
on protein half-life.


title: Dynamical symmetries in Brans-Dicke cosmology

abstract:
  In the context of generalised Brans-Dicke cosmology we use the Killing
tensors of the minisuperspace in order to determine the unspecified potential
of a scalar-tensor gravity theory. Specifically, based on the existence of
contact symmetries of the field equations, we find four types of potentials
which provide exactly integrable dynamical systems. We investigate the
dynamical properties of these potentials by using a critical point analysis and
we find solutions which lead to cosmic acceleration and under specific
conditions we can have de-Sitter points as stable late-time attractors.


title:
Students' network integration as a predictor of persistence in
  introductory physics courses

abstract:
  Increasing student retention (successfully finishing a particular course) and
persistence (continuing through a sequence of courses or the major area of
study) is currently a major challenge for universities. While students'
academic and social integration into an institution seems to be vital for
student retention, research into the effect of interpersonal interactions is
rare. We use network analysis as an approach to investigate academic and social
experiences of students in the classroom. In particular, centrality measures
identify patterns of interaction that contribute to integration into the
university. Using these measures, we analyze how position within a social
network in a Modeling Instruction (MI) course -- an introductory physics course
that strongly emphasizes interactive learning -- predicts their persistence in
taking a subsequent physics course. Students with higher centrality at the end
of the first semester of MI are more likely to enroll in a second semester of
MI. Moreover, we found that chances of successfully predicting individual
student's persistence based on centrality measures are fairly high -- up to
$75\%$, making the centrality a good predictor of persistence. These findings
suggest that increasing student social integration may help in improving
persistence in science, technology, engineering, and mathematics fields.


title:
Gaussian intrinsic entanglement: An entanglement quantifier based on
  secret correlations

abstract:
  Intrinsic entanglement (IE) is a quantity which aims at quantifying bipartite
entanglement carried by a quantum state as an optimal amount of the intrinsic
information that can be extracted from the state by measurement. We investigate
in detail the properties of a Gaussian version of IE, the so-called Gaussian
intrinsic entanglement (GIE). We show explicitly how GIE simplifies to the
mutual information of a distribution of outcomes of measurements on a
conditional state obtained by a measurement on a purifying subsystem of the
analyzed state, which is first minimized over all measurements on the purifying
subsystem and then maximized over all measurements on the conditional state. By
constructing for any separable Gaussian state a purification and a measurement
on the purifying subsystem which projects the purification onto a product
state, we prove that GIE vanishes on all Gaussian separable states. Via
realization of quantum operations by teleportation, we further show that GIE is
non-increasing under Gaussian local trace-preserving operations and classical
communication. For pure Gaussian states and a reduction of the
continuous-variable GHZ state, we calculate GIE analytically and we show that
it is always equal to the Gaussian R\'{e}nyi-2 entanglement. We also extend the
analysis of IE to a non-Gaussian case by deriving an analytical lower bound on
IE for a particular form of the non-Gaussian continuous-variable Werner state.
Our results indicate that mapping of entanglement onto intrinsic information is
capable of transmitting also quantitative properties of entanglement and that
this property can be used for introduction of a quantifier of Gaussian
entanglement which is a compromise between computable and physically meaningful
entanglement quantifiers.


title: Non-Markovian quantum thermodynamics: laws and fluctuation theorems

abstract:
  This work brings together Keldysh non-equilibrium quantum theory and
thermodynamics, by showing that a real-time diagrammatic technique is an
equivalent of stochastic thermodynamics for non-Markovian quantum machines
(heat engines, refrigerators, etc). Symmetries are found between quantum
trajectories and their time-reverses on the Keldysh contour, for any
interacting quantum system coupled to ideal reservoirs of electrons, phonons or
photons. These lead to quantum fluctuation theorems the same as the well-known
classical ones (Jarzynski and Crooks equalities, integral fluctuation theorem,
etc), whether the system's dynamics are Markovian or not. Some of these are
also shown to hold for non-factorizable initial states. The sequential
tunnelling approximation and the cotunnelling approximation are both shown to
respect the symmetries that ensure the fluctuation theorems. For all initial
states, energy conservation ensures that the first law of thermodynamics holds
on average, while the above symmetries ensures that the second law of
thermodynamics holds on average, even if fluctuations violate it. [ERRATUM
added: March 2021]


title:
Algorithms and analyses for stochastic optimization for turbofan noise
  reduction using parallel reduced-order modeling

abstract:
  Simulation-based optimization of acoustic liner design in a turbofan engine
nacelle for noise reduction purposes can dramatically reduce the cost and time
needed for experimental designs. Because uncertainties are inevitable in the
design process, a stochastic optimization algorithm is posed based on the
conditional value-at-risk measure so that an ideal acoustic liner impedance is
determined that is robust in the presence of uncertainties. A parallel
reduced-order modeling framework is developed that dramatically improves the
computational efficiency of the stochastic optimization solver for a realistic
nacelle geometry. The reduced stochastic optimization solver takes less than
500 seconds to execute. In addition, well-posedness and finite element error
analyses of the state system and optimization problem are provided.


title: Double Principal Bundles

abstract:
  We define double principal bundles (DPBs), for which the frame bundle of a
double vector bundle, double Lie groups and double homogeneous spaces are basic
examples. It is shown that a double vector bundle can be realized as the
associated bundle of its frame bundle. Also dual structures, gauge
transformations and connections in DPBs are investigated.


title:
Imaging the Spin Texture of a Skyrmion Under Ambient Conditions Using an
  Atomic-Sized Sensor

abstract:
  Magnetic skyrmions are two-dimensional non-collinear spin textures
characterised by an integer topological number. They commonly crystallise at
low temperatures in bulk noncentrosymmetric ferromagnets where the lack of
inversion symmetry leads to an antisymmetric component of the exchange
interaction. Recently, stable room-temperature skyrmions were reported in
stacks of thin magnetic films where antisymmetric exchange results from broken
symmetry at the interface. Determining the spin structure of these
technologically-relevant skyrmions in the presence of external magnetic fields
has remained a key experimental challenge. Here, we use the single electron
spin of a Nitrogen-Vacancy (NV) centre in diamond to perform scanning
magnetometry of skyrmions in Pt/Co/Ta multilayers under ambient conditions. We
introduce a novel method to assess the manifold of spin textures compatible
with the measured local magnetic fields and identify physically allowed
configurations based on the topology of the resulting solution. We determine
that the underlying magnetization pattern for the skyrmion is consistent with a
cycloid (or N\'eel)-like spin texture, in agreement with theoretical
predictions for interfacial antisymmetric exchange interaction. Our results
open up wide-ranging possibilities in quantitative model-free imaging of
two-dimensional spin structures using scanning NV magnetometry.


title: Fuzzy paraphrases in learning word representations with a lexicon

abstract:
  A synonym of a polysemous word is usually only the paraphrase of one sense
among many. When lexicons are used to improve vector-space word
representations, such paraphrases are unreliable and bring noise to the
vector-space. The prior works use a coefficient to adjust the overall learning
of the lexicons. They regard the paraphrases equally. In this paper, we propose
a novel approach that regards the paraphrases diversely to alleviate the
adverse effects of polysemy. We annotate each paraphrase with a degree of
reliability. The paraphrases are randomly eliminated according to the degrees
when our model learns word representations. In this way, our approach drops the
unreliable paraphrases, keeping more reliable paraphrases at the same time. The
experimental results show that the proposed method improves the word vectors.
Our approach is an attempt to address the polysemy problem keeping one vector
per word. It makes the approach easier to use than the conventional methods
that estimate multiple vectors for a word. Our approach also outperforms the
prior works in the experiments.


title: emgr - The Empirical Gramian Framework

abstract:
  System Gramian matrices are a well-known encoding for properties of
input-output systems such as controllability, observability or minimality.
These so-called system Gramians were developed in linear system theory for
applications such as model order reduction of control systems. Empirical
Gramian are an extension to the system Gramians for parametric and nonlinear
systems as well as a data-driven method of computation. The empirical Gramian
framework - emgr - implements the empirical Gramians in a uniform and
configurable manner, with applications such as Gramian-based (nonlinear) model
reduction, decentralized control, sensitivity analysis, parameter
identification and combined state and parameter reduction.


title:
Knowledge-infused and Consistent Complex Event Processing over Real-time
  and Persistent Streams

abstract:
  Emerging applications in Internet of Things (IoT) and Cyber-Physical Systems
(CPS) present novel challenges to Big Data platforms for performing online
analytics. Ubiquitous sensors from IoT deployments are able to generate data
streams at high velocity, that include information from a variety of domains,
and accumulate to large volumes on disk. Complex Event Processing (CEP) is
recognized as an important real-time computing paradigm for analyzing
continuous data streams. However, existing work on CEP is largely limited to
relational query processing, exposing two distinctive gaps for query
specification and execution: (1) infusing the relational query model with
higher level knowledge semantics, and (2) seamless query evaluation across
temporal spaces that span past, present and future events. These allow
accessible analytics over data streams having properties from different
disciplines, and help span the velocity (real-time) and volume (persistent)
dimensions. In this article, we introduce a Knowledge-infused CEP (X-CEP)
framework that provides domain-aware knowledge query constructs along with
temporal operators that allow end-to-end queries to span across real-time and
persistent streams. We translate this query model to efficient query execution
over online and offline data streams, proposing several optimizations to
mitigate the overheads introduced by evaluating semantic predicates and in
accessing high-volume historic data streams. The proposed X-CEP query model and
execution approaches are implemented in our prototype semantic CEP engine,
SCEPter. We validate our query model using domain-aware CEP queries from a
real-world Smart Power Grid application, and experimentally analyze the
benefits of our optimizations for executing these queries, using event streams
from a campus-microgrid IoT deployment.


title:
Holographic Thermalization and Generalized Vaidya-AdS Solutions in
  Massive Gravity

abstract:
  We investigate the effect of massive graviton on the holographic
thermalization process. Before doing this, we first find out the generalized
Vaidya-AdS solutions in the de Rham-Gabadadze-Tolley (dRGT) massive gravity by
directly solving the gravitational equations. Then, we study the thermodynamics
of these Vaidya-AdS solutions by using the Minsner-Sharp energy and unified
first law, which also shows that the massive gravity is in a thermodynamic
equilibrium state. Moreover, we adopt the two-point correlation function at
equal time to explore the thermalization process in the dual field theory, and
to see how the graviton mass parameter affects this process from the viewpoint
of AdS/CFT correspondence. Our results show that the graviton mass parameter
will increase the holographic thermalization process.


title: Characterizations and Properties of Graphs of Baire Functions

abstract:
  Let $X$ be a paracompact topological space and $Y$ be a Banach space. In this
paper, we will characterize the Baire-1 functions $f:X\rightarrow{Y}$ by their
graph: namely, we will show that $f$ is a Baire-1 function if and only if its
graph $gr(f)$ is the intersection of a sequence $(G_n)_{n=1}^{\infty}$ of open
sets in $X\times{Y}$ such that for all $x\in{X}$ and $n\in\mathbb{N}$ the
vertical section of $G_n$ is a convex set, whose diameter tends to $0$ as
$n\rightarrow\infty$. Afterwards, we will discuss a similar question concerning
functions of higher Baire classes and formulate some generalized results in
slightly different settings: for example we require the domain to be a metrized
Suslin space, while the codomain is a separable Fr\'echet space. Finally, we
will characterize the accumulation set of graphs of Baire-2 functions between
certain spaces.


title:
Distributed Scheme for Interference Mitigation of WBANs Using
  Predictable Channel Hopping

abstract:
  When sensors of different coexisting wireless body area networks (WBANs)
transmit at the same time using the same channel, a co-channel interference is
experienced and hence the performance of the involved WBANs may be degraded. In
this paper, we exploit the 16 channels available in the 2.4 GHz international
band of ZIGBEE, and propose a distributed scheme that avoids interference
through predictable channel hopping based on Latin rectangles, namely, CHIM. In
the proposed CHIM scheme, each WBAN's coordinator picks a Latin rectangle whose
rows are ZIGBEE channels and columns are sensor IDs. Based on the Latin
rectangle of the individual WBAN, each sensor is allocated a backup time-slot
and a channel to use if it experiences interference such that collisions among
different transmissions of coexisting WBANs are minimized. We further present a
mathematical analysis that derives the collision probability of each sensor's
transmission in the network. In addition, the efficiency of CHIM in terms of
transmission delay and energy consumption minimization are validated by
simulations.


title:
KaTie: for parton-level event generation with k_T-dependent initial
  states

abstract:
  KaTie is a parton-level event generator for hadron scattering processes that
can deal with partonic initial-state momenta with an explicit transverse
momentum dependence causing them to be space-like. Provided with the necessary
transverse momentum dependent parton density functions, it calculates the
off-shell matrix elements and performs the phase space importance sampling to
produce weighted events, for example in the Les Houches Event File format. It
can deal with arbitrary processes within the Standard Model, for up to four
final-state particles and beyond. Furthermore, it can produce events for
single-parton scattering as well as for multi-parton scattering.


title: Silicon Color Filters for Light-Recycling Displays

abstract:
  We propose a set of silicon reflective transmission filters for
light-recycling displays that are compatible with high-throughput
nanofabrication technologies and have excellent angular stability.


title:
Applications of Livingston-type inequalities to the generalized Zalcman
  functional

abstract:
  We obtain sharp estimates for a generalized Zalcman coefficient functional
with a complex parameter for the Hurwitz class and the Noshiro-Warschawski
class of univalent functions as well as for the closed convex hulls of the
convex and starlike functions by using an inequality from [6]. In particular,
we generalize an inequality proved by Ma for starlike functions and answer a
question from his paper [16]. Finally, we prove an asymptotic version of the
generalized Zalcman conjecture for univalent functions and discuss various
related or equivalent statements which may shed further light on the problem.


title: Improving variational methods via pairwise linear response identities

abstract:
  Inference methods are often formulated as variational approximations: these
approximations allow easy evaluation of statistics by marginalization or linear
response, but these estimates can be inconsistent. We show that by introducing
constraints on covariance, one can ensure consistency of linear response with
the variational parameters, and in so doing inference of marginal probability
distributions is improved. For the Bethe approximation and its generalizations,
improvements are achieved with simple choices of the constraints. The
approximations are presented as variational frameworks; iterative procedures
related to message passing are provided for finding the minima.


title:
Wearable Vision Detection of Environmental Fall Risks using
  Convolutional Neural Networks

abstract:
  In this paper, a method to detect environmental hazards related to a fall
risk using a mobile vision system is proposed. First-person perspective videos
are proposed to provide objective evidence on cause and circumstances of
perturbed balance during activities of daily living, targeted to seniors. A
classification problem was defined with 12 total classes of potential fall
risks, including slope changes (e.g., stairs, curbs, ramps) and surfaces (e.g.,
gravel, grass, concrete). Data was collected using a chest-mounted GoPro
camera. We developed a convolutional neural network for automatic feature
extraction, reduction, and classification of frames. Initial results, with a
mean square error of 8%, are promising.


title: A Framework for Searching for General Artificial Intelligence

abstract:
  There is a significant lack of unified approaches to building generally
intelligent machines. The majority of current artificial intelligence research
operates within a very narrow field of focus, frequently without considering
the importance of the 'big picture'. In this document, we seek to describe and
unify principles that guide the basis of our development of general artificial
intelligence. These principles revolve around the idea that intelligence is a
tool for searching for general solutions to problems. We define intelligence as
the ability to acquire skills that narrow this search, diversify it and help
steer it to more promising areas. We also provide suggestions for studying,
measuring, and testing the various skills and abilities that a human-level
intelligent machine needs to acquire. The document aims to be both
implementation agnostic, and to provide an analytic, systematic, and scalable
way to generate hypotheses that we believe are needed to meet the necessary
conditions in the search for general artificial intelligence. We believe that
such a framework is an important stepping stone for bringing together
definitions, highlighting open problems, connecting researchers willing to
collaborate, and for unifying the arguably most significant search of this
century.


title: A trivial tail homology for non $A$-adequate links

abstract:
  We prove a conjecture of Rozansky's concerning his categorification of the
tail of the colored Jones polynomial for an $A$-adequate link. We show that the
tail homology groups he constructs are trivial for non $A$-adequate links.


title: Engagement dynamics and sensitivity analysis of YouTube videos

abstract:
  YouTube, with millions of content creators, has become the preferred
destination for watching videos online. Through the Partner program, YouTube
allows content creators to monetize their popular videos. Of significant
importance for content creators is which meta-level features (e.g. title, tag,
thumbnail) are most sensitive for promoting video popularity. The popularity of
videos also depends on the social dynamics, i.e. the interaction of the content
creators (or channels) with YouTube users. Using real-world data consisting of
about 6 million videos spread over 25 thousand channels, we empirically examine
the sensitivity of YouTube meta-level features and social dynamics. The key
meta-level features that impact the view counts of a video include: first day
view count , number of subscribers, contrast of the video thumbnail, Google
hits, number of keywords, video category, title length, and number of
upper-case letters in the title respectively and illustrate that these
meta-level features can be used to estimate the popularity of a video. In
addition, optimizing the meta-level features after a video is posted increases
the popularity of videos. In the context of social dynamics, we discover that
there is a causal relationship between views to a channel and the associated
number of subscribers. Additionally, insights into the effects of scheduling
and video playthrough in a channel are also provided. Our findings provide a
useful understanding of user engagement in YouTube.


title: Mitigating Inter-network Interference in LoRa Networks

abstract:
  Long Range (LoRa) is a popular technology used to construct Low-Power
Wide-Area Network (LPWAN) networks. Given the popularity of LoRa it is likely
that multiple independent LoRa networks are deployed in close proximity. In
this situation, neighbouring networks interfere and methods have to be found to
combat this interference. In this paper we investigate the use of directional
antennae and the use of multiple base stations as methods of dealing with
inter-network interference. Directional antennae increase signal strength at
receivers without increasing transmission energy cost. Thus, the probability of
successfully decoding the message in an interference situation is improved.
Multiple base stations can alternatively be used to improve the probability of
receiving a message in a noisy environment. We compare the effectiveness of
these two approaches via simulation. Our findings show that both methods are
able to improve LoRa network performance in interference settings. However, the
results show that the use of multiple base stations clearly outperforms the use
of directional antennae. For example, in a setting where data is collected from
600 nodes which are interfered by four networks with 600 nodes each, using
three base stations improves the Data Extraction Rate (DER) from 0.24 to 0.56
while the use of directional antennae provides an increase to only 0.32.


title: Analytic Interatomic Forces in the Random Phase Approximation

abstract:
  We discuss that in the random phase approximation (RPA) the first derivative
of the energy with respect to the Green's function is the self-energy in the GW
approximation. This relationship allows us to derive compact equations for the
RPA interatomic forces. We also show that position dependent overlap operators
are elegantly incorporated in the present framework. The RPA force equations
have been implemented in the projector augmented wave formalism, and we present
illustrative applications, including ab initio molecular dynamics simulations,
the calculation of phonon dispersion relations for diamond and graphite, as
well as structural relaxations for water on boron nitride. The present
derivation establishes a concise framework for forces within perturbative
approaches and is also applicable to more involved approximations for the
correlation energy.


title: Infimal convolution of data discrepancies for mixed noise removal

abstract:
  We consider the problem of image denoising in the presence of noise whose
statistical properties are a combination of two different distributions. We
focus on noise distributions that are frequently considered in applications, in
particular mixtures of salt & pepper and Gaussian noise, and Gaussian and
Poisson noise. We derive a variational image denoising model that features a
total variation regularisation term and a data discrepancy that features the
mixed noise as an infimal convolution of discrepancy terms of the single-noise
distributions. We give a statistical derivation of this model by joint Maximum
A-Posteriori (MAP) estimation, and discuss in particular its interpretation as
the MAP of a so-called infinity convolution of two noise distributions.
Moreover, classical single-noise models are recovered asymptotically as the
weighting parameters go to infinity. The numerical solution of the model is
computed using second order Newton-type methods. Numerical results show the
decomposition of the noise into its constituting components. The paper is
furnished with several numerical experiments and comparisons with other
existing methods dealing with the mixed noise case are shown.


title: The Next Generation Transit Survey - Prototyping Phase

abstract:
  We present the prototype telescope for the Next Generation Transit Survey,
which was built in the UK in 2008/09 and tested on La Palma in the Canary
Islands in 2010. The goals for the prototype system were severalfold: to
determine the level of systematic noise in an NGTS-like system; demonstrate
that we can perform photometry at the (sub) millimagnitude level on transit
timescales across a wide field; show that it is possible to detect transiting
super-Earth and Neptune-sized exoplanets and prove the technical feasibility of
the proposed planet survey. We tested the system for around 100 nights and met
each of the goals above. Several key areas for improvement were highlighted
during the prototyping phase. They have been subsequently addressed in the
final NGTS facility which was recently commissioned at ESO Cerro Paranal,
Chile.


title: Towards Automatic Resource Bound Analysis for OCaml

abstract:
  This article presents a resource analysis system for OCaml programs. This
system automatically derives worst-case resource bounds for higher-order
polymorphic programs with user-defined inductive types. The technique is
parametric in the resource and can derive bounds for time, memory allocations
and energy usage. The derived bounds are multivariate resource polynomials
which are functions of different size parameters that depend on the standard
OCaml types. Bound inference is fully automatic and reduced to a linear
optimization problem that is passed to an off-the-shelf LP solver. Technically,
the analysis system is based on a novel multivariate automatic amortized
resource analysis (AARA). It builds on existing work on linear AARA for
higher-order programs with user-defined inductive types and on multivariate
AARA for first-order programs with built-in lists and binary trees. For the
first time, it is possible to automatically derive polynomial bounds for
higher-order functions and polynomial bounds that depend on user-defined
inductive types. Moreover, the analysis handles programs with side effects and
even outperforms the linear bound inference of previous systems. At the same
time, it preserves the expressivity and efficiency of existing AARA techniques.
The practicality of the analysis system is demonstrated with an implementation
and integration with Inria's OCaml compiler. The implementation is used to
automatically derive resource bounds for 411 functions and 6018 lines of code
derived from OCaml libraries, the CompCert compiler, and implementations of
textbook algorithms. In a case study, the system infers bounds on the number of
queries that are sent by OCaml programs to DynamoDB, a commercial NoSQL cloud
database service.


title:
Signatures of protein structure in the cooperative gating of
  mechanosensitive ion channels

abstract:
  Membrane proteins deform the surrounding lipid bilayer, which can lead to
membrane-mediated interactions between neighboring proteins. Using the
mechanosensitive channel of large conductance (MscL) as a model system, we
demonstrate how the observed differences in protein structure can affect
membrane-mediated interactions and cooperativity among membrane proteins. We
find that distinct oligomeric states of MscL lead to distinct gateway states
for the clustering of MscL, and predict signatures of MscL structure and
spatial organization in the cooperative gating of MscL. Our modeling approach
establishes a quantitative relation between the observed shapes and cooperative
function of membrane~proteins.

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


title:
New Dualities and Misleading Anomaly Matchings from Outer-automorphism
  Twists

abstract:
  We study four-dimensional N=1, 2 superconformal theory in class S obtained by
compactifying the 6d N=(2, 0) theory on a Riemann surface C with
outer-automorphism twist lines. From the pair-of-pants decompositions C we find
various dual descriptions for the same theory having distinct gauge groups. We
show that the various configurations of the twist line give rise to dual
descriptions for the identical theory. We compute the 't Hooft anomaly
coefficients and the superconformal indices to test dualities. Surprisingly, we
find that the class S theories with twist lines wrapping 1-cycles of C have the
identical 't Hooft anomalies as the ones without the twist line, whereas the
superconformal indices differ. This provides a set of examples where the
anomaly matching is insufficient to test dualities.


title: Characterization of Surface-Plasmon Polaritons at Lossy Interfaces

abstract:
  We characterize surface-plasmon polaritons at lossy planar interfaces between
one dispersive and one nondispersive linear isotropic homogeneous media, i.e.,
materials or metamaterials. Specifically we solve Maxwell's equations to obtain
strict bounds for the permittivity and permeability of these media such that
satisfying these bounds implies surface-plasmon polaritons successfully
propagate at the interface, and violation of the bounds impedes propagation,
i.e., the field delocalizes from the surface into the bulk. Our
characterization of surface-plasmon polaritons is valuable for checking
viability of a proposed application, and, as an example, we employ our method
to falsify a previous prediction that surface-plasmon propagation through a
surface of a double-negative refractive index medium occurs for any
permittivity and permeability; instead we show that propagation can occur only
for certain medium parameters.


title: Self-adjoint indefinite Laplacians

abstract:
  Let $\Omega_-$ and $\Omega_+$ be two bounded smooth domains in
$\mathbb{R}^n$, $n\ge 2$, separated by a hypersurface $\Sigma$. For $\mu>0$,
consider the function $h_\mu=1_{\Omega_-}-\mu 1_{\Omega_+}$. We discuss
self-adjoint realizations of the operator $L_{\mu}=-\nabla\cdot h_\mu \nabla$
in $L^2(\Omega_-\cup\Omega_+)$ with the Dirichlet condition at the exterior
boundary. We show that $L_\mu$ is always essentially self-adjoint on the
natural domain (corresponding to transmission-type boundary conditions at the
interface $\Sigma$) and study some properties of its unique self-adjoint
extension $\mathcal{L}_\mu:=\overline{L_\mu}$. If $\mu\ne 1$, then
$\mathcal{L}_\mu$ simply coincides with $L_\mu$ and has compact resolvent. If
$n=2$, then $\mathcal{L}_1$ has a non-empty essential spectrum,
$\sigma_\mathrm{ess}(\mathcal{L}_{1})=\{0\}$. If $n\ge 3$, the spectral
properties of $\mathcal{L}_1$ depend on the geometry of $\Sigma$. In
particular, it has compact resolvent if $\Sigma$ is the union of disjoint
strictly convex hypersurfaces, but can have a non-empty essential spectrum if a
part of $\Sigma$ is flat. Our construction features the method of boundary
triplets, and the problem is reduced to finding the self-adjoint extensions of
a pseudodifferential operator on $\Sigma$. We discuss some links between the
resulting self-adjoint operator $\mathcal{L}_\mu$ and some effects observed in
negative-index materials.


title:
Nonequilibrium gas-liquid transition in the driven-dissipative photonic
  lattice

abstract:
  We study the nonequilibrium steady state of the driven-dissipative
Bose-Hubbard model with Kerr nonlinearity. Employing a mean-field decoupling
for the intercavity hopping $J$, we find that the steep crossover between low
and high photon-density states inherited from the single cavity transforms into
a gas$-$liquid bistability at large cavity-coupling $J$. We formulate a van der
Waals like gas$-$liquid phenomenology for this nonequilibrium situation and
determine the relevant phase diagrams, including a new type of diagram where a
lobe-shaped boundary separates smooth crossovers from sharp, hysteretic
transitions. Calculating quantum trajectories for a one-dimensional system, we
provide insights into the microscopic origin of the bistability.


title:
An extension of Bakhvalov's theorem for systems of conservation laws
  with damping

abstract:
  For $2\X2$ systems of conservation laws satisfying Bakhvalov conditions, we
present a class of damping terms that still yield the existence of global
solutions with periodic initial data of possibly large bounded total variation
per period. We also address the question of the decay of the periodic solution.
As applications we consider the systems of isentropic gas dynamics, with
pressure obeying a $\gamma$-law, for the physical range $\gamma\ge1$, and also
for the "non-physical" range $0<\gamma<1$, both in the classical Lagrangian and
Eulerian formulation, and in the relativistic setting. We give complete details
for the case $\gamma=1$, and also analyze the general case when $|\gamma-1|$ is
small. Further, our main result also establishes the decay of the periodic
solution.


title:
Successive Injection of Opposite Magnetic Helicity in Solar Active
  Region NOAA 11928

abstract:
  Understanding the nature and evolution of the photospheric helicity flux
transfer is a key to reveal the role of magnetic helicity in coronal dynamics
of solar active regions. Using SDO/HMI photospheric vector magnetograms and the
derived flow velocity field, we computed boundary driven helicity flux with a
12 minute cadence during the emergence of AR 11928. Accounting the foot point
connectivity defined by non-linear force-free magnetic extrapolations, we
derived and analyzed the corrected distribution of helicity flux maps. The
photospheric helicity flux injection is found to changes sign during the steady
emergence of the AR. This reversal is confirmed with the evolution of the
photospheric electric currents and with the coronal connectivity as observed in
EUV wavelengths with SDO/AIA. During about the three first days of emergence,
the AR coronal helicity is positive while later on the field configuration is
close to a potential field. As theoretically expected, the magnetic helicity
cancelation is associated to enhanced coronal activity. The study suggests a
boundary driven transformation of the chirality in the global AR magnetic
structure. This may be the result of the emergence of a flux rope with positive
twist around its apex while it has negative twist in its legs. The origin of
such mixed helicity flux rope in the convective zone is challenging for models.


title: Quarkonium production at collider energies in Small-$x$ formalism

abstract:
  I present a short review of recent studies of quarkonium production in
proton-proton and proton-nucleus collisions at collider energies in Small-$x$
formalism.


title: Cosmological Implications of QGP Bulk Viscosity

abstract:
  Recent studies of the hot QCD matter indicate that the bulk viscosity
($\zeta$) of quark-gluon plasma (QGP) rises sharply near the critical point of
the QCD phase transition. In this work, we show that such a sharp rise of the
bulk viscosity will lead to an effective negative pressure near the critical
temperature, $T_{c}$ which in turn drives the Universe to inflate. This
inflation has a natural graceful exist when the viscous effect evanesce. We
estimate that, depending upon the peak value of $\zeta$, universe expands by a
factor of $10$ to $80$ times in a very short span ($\Delta t\sim 10^{-8}$
seconds). Another important outcome of the bulk viscosity dominated dynamics is
the cavitation of QGP around $T \sim 1.5T_{c}$. This would lead to the
phenomenon of formation of cavitation bubbles within the QGP phase. The above
scenario is independent of the order of QCD phase transition. We delineate some
of the important cosmological consequences of the inflation and the cavitation.


title: Complex Langevin Dynamics in 1+1d QCD at Non-Zero Densities

abstract:
  We present our results obtained from gauge cooled complex Langevin
simulations in 1+1d QCD at non-zero densities in the strong coupling regime
with unrooted staggered fermions. For small quark masses there are regions of
the chemical potential where this method fails to reproduce correct results. In
these parameter ranges we studied the effect of different gauge cooling schemes
on the distributions of the fermion determinant as well as of observables.


title:
Preservation of quantum correlations in femtosecond light pulse train
  within atomic ensemble

abstract:
  In this paper, we examined a possibility of preservation of a substantially
multimode radiation in a single cell of quantum memory. As a light source we
considered a synchronously pumped optical parametric oscillator (SPOPO). As it
was shown in [1-4], SPOPO radiation has a large number of the correlated modes
making it attractive for the purposes of the quantum communication and
computing. We showed that these correlations can be mapped on the longitudinal
spin waves of the memory cell and be restored later in the readout light. The
efficiencies of the writing and readout depend on the mode structure of the
memory determined by a mechanism of the light-matter interaction under
consideration (the non-resonance Raman interaction) and by the profile of the
driving light field. We showed that like the initial light pulse train, the
restored one can be represented by a set of squeezed supermodes. The mapping of
the quantum multimode correlations on the material medium offers opportunities
to manipulate the quantum states within the memory cell followed by the reading
of the transformed state.


title:
Distributed Scheme for Interference Mitigation of Coexisting WBANs Using
  Latin Rectangles

abstract:
  The performance of wireless body area networks (WBANs) may be degraded due to
co-channel interference, i.e., when sensors of different coexisting WBANs
transmit at the same time-slots using the same channel. In this paper, we
exploit the 16 channels available in the 2.4 GHz unlicensed international band
of ZIGBEE, and propose a distributed scheme that opts to avoid interference
through channel to time-slot hopping based on Latin rectangles, DAIL. In DAIL,
each WBAN's coordinator picks a Latin rectangle whose rows are ZIGBEE channels
and columns are time-slots of its superframe. Subsequently, it assigns a unique
symbol to each sensor; this latter forms a transmission pattern according to
distinct positions of its symbol in the rectangle, such that collisions among
different transmissions of coexisting WBANs are minimized. We further present
an analytical model that derives bounds on the collision probability of each
sensor's transmission in the network. In addition, the efficiency of DAIL in
interference mitigation has been validated by simulations.


title:
Density Induced Phase Transitions in the Schwinger Model: A Study with
  Matrix Product States

abstract:
  We numerically study the zero temperature phase structure of the multiflavor
Schwinger model at nonzero chemical potential. Using matrix product states, we
reproduce analytical results for the phase structure for two flavors in the
massless case and extend the computation to the massive case, where no
analytical predictions are available. Our calculations allow us to locate phase
transitions in the mass-chemical potential plane with great precision and
provide a concrete example of tensor networks overcoming the sign problem in a
lattice gauge theory calculation.


title: Double-electron ionization driven by inhomogeneous fields

abstract:
  Electron-electron correlation effects play an instrumental role in our
understanding of sequential (SDI) and non-sequential double ionization (NSDI)
mechanisms. Here, we present a theoretical study of NSDI driven by
plasmonic-enhanced spatial inhomogeneous fields. By numerically solving the
time-dependent Schr\"odinger equation for a linear reduced model of He and a
double-electron time-evolution probability analysis, we provide evidence for
the enhancement effects in NSDI showing that the double ionization yield at
lower laser peak intensities is increased due to the inhomogeneity of the laser
field. Furthermore, our quantum mechanical model, as well as classical
trajectory Monte Carlo simulations, show that inhomogeneous fields are a useful
tool for splitting the binary and recoil processes in the rescattering
scenario.


title:
Extension Complexity Lower Bounds for Mixed-Integer Extended
  Formulations

abstract:
  We prove that any mixed-integer linear extended formulation for the matching
polytope of the complete graph on $n$ vertices, with a polynomial number of
constraints, requires $\Omega(\sqrt{\sfrac{n}{\log n}})$ many integer
variables. By known reductions, this result extends to the traveling salesman
polytope. This lower bound has various implications regarding the existence of
small mixed-integer mathematical formulations of common problems in operations
research. In particular, it shows that for many classic vehicle routing
problems and problems involving matchings, any compact mixed-integer linear
description of such a problem requires a large number of integer variables.
This provides a first non-trivial lower bound on the number of integer
variables needed in such settings.


title:
Inter-WBANs Interference Mitigation Using Orthogonal Walsh Hadamard
  Codes

abstract:
  A Wireless Body Area Network (WBAN) provides health care services. The
performance and utility of WBANs can be degraded due to interference. In this
paper, our contribution for co-channel interference mitigation among coexisting
WBANs is threefold. First, we propose a distributed orthogonal code allocation
scheme, namely, OCAIM, where, each WBAN generates sensor interference lists
(SILs), and then all sensors belonging to these lists are allocated orthogonal
codes. Secondly, we propose a distributed time reference correlation scheme,
namely, DTRC, that is used as a building block of OCAIM. DTRC enables eachWBAN
to generate a virtual time-based pattern to relate the different superframes.
Accordingly, DTRC provides each WBAN with the knowledge about, 1) which
superframes and, 2) which time-slots of those superframes interfere with the
time-slots within its superframe. Thirdly, we further analyze the success and
collision probabilities of frames transmissions when the number of coexisting
WBANs grows. The simulation results demonstrate that OCAIM outperforms other
competing schemes in terms of interference mitigation and power savings.


title:
A Novel Hybrid Beamforming Algorithm with Unified Analog Beamforming by
  Subspace Construction Based on Partial CSI for Massive MIMO-OFDM Systems

abstract:
  Hybrid beamforming (HB) has been widely studied for reducing the number of
costly radio frequency (RF) chains in massive multiple-input multiple-output
(MIMO) systems. However, previous works on HB are limited to a single user
equipment (UE) or a single group of UEs, employing the frequency-flat
first-level analog beamforming (AB) that cannot be applied to multiple groups
of UEs served in different frequency resources in an orthogonal
frequency-division multiplexing (OFDM) system. In this paper, a novel HB
algorithm with unified AB based on the spatial covariance matrix (SCM)
knowledge of all UEs is proposed for a massive MIMO-OFDM system in order to
support multiple groups of UEs. The proposed HB method with a much smaller
number of RF chains can achieve more than 95% performance of full digital
beamforming. In addition, a novel practical subspace construction (SC)
algorithm based on partial channel state information is proposed to estimate
the required SCM. The proposed SC method can offer more than 97% performance of
the perfect SCM case. With the proposed methods, significant cost and power
savings can be achieved without large loss in performance. Furthermore, the
proposed methods can be applied to massive MIMO-OFDM systems in both
time-division duplex and frequency-division duplex.


title: Deep counter networks for asynchronous event-based processing

abstract:
  Despite their advantages in terms of computational resources, latency, and
power consumption, event-based implementations of neural networks have not been
able to achieve the same performance figures as their equivalent
state-of-the-art deep network models. We propose counter neurons as minimal
spiking neuron models which only require addition and comparison operations,
thus avoiding costly multiplications. We show how inference carried out in deep
counter networks converges to the same accuracy levels as are achieved with
state-of-the-art conventional networks. As their event-based style of
computation leads to reduced latency and sparse updates, counter networks are
ideally suited for efficient compact and low-power hardware implementation. We
present theory and training methods for counter networks, and demonstrate on
the MNIST benchmark that counter networks converge quickly, both in terms of
time and number of operations required, to state-of-the-art classification
accuracy.


title: Linear Programming Heuristics for the Graph Isomorphism Problem

abstract:
  An isomorphism between two graphs is a bijection between their vertices that
preserves the edges. We consider the problem of determining whether two finite
undirected weighted graphs are isomorphic, and finding an isomorphism relating
them if the answer is positive. In this paper we introduce effective
probabilistic linear programming (LP) heuristics to solve the graph isomorphism
problem. We motivate our heuristics by showing guarantees under some
conditions, and present numerical experiments that show effectiveness of these
heuristics in the general case.


title:
The Concrete Distribution: A Continuous Relaxation of Discrete Random
  Variables

abstract:
  The reparameterization trick enables optimizing large scale stochastic
computation graphs via gradient descent. The essence of the trick is to
refactor each stochastic node into a differentiable function of its parameters
and a random variable with fixed distribution. After refactoring, the gradients
of the loss propagated by the chain rule through the graph are low variance
unbiased estimators of the gradients of the expected loss. While many
continuous random variables have such reparameterizations, discrete random
variables lack useful reparameterizations due to the discontinuous nature of
discrete states. In this work we introduce Concrete random
variables---continuous relaxations of discrete random variables. The Concrete
distribution is a new family of distributions with closed form densities and a
simple reparameterization. Whenever a discrete stochastic node of a computation
graph can be refactored into a one-hot bit representation that is treated
continuously, Concrete stochastic nodes can be used with automatic
differentiation to produce low-variance biased gradients of objectives
(including objectives that depend on the log-probability of latent stochastic
nodes) on the corresponding discrete graph. We demonstrate the effectiveness of
Concrete relaxations on density estimation and structured prediction tasks
using neural networks.


title: Quantum Effects on the Deflection of Light and the Gauss-Bonnet Theorem

abstract:
  In this letter we apply the Gauss--Bonnet theorem (GB) to calculate the
deflection angle by a quantum corrected Schwarzschild black hole in the weak
limit approximation. In particular we calculate the light deflection by two
types of quantum corrected black holes: the renormalization group improved
Schwarzschild solution and the quantum corrected Schwarzschild solution in
Bohmian quantum mechanics. We start from the corresponding optical metrics to
use then the GB theorem and calculate the Gaussian curvature in both cases. We
calculate the leading terms of the deflection angle and show that quantum
corrections modifies the deflection angle in both solutions. Finally by
performing geodesics calculations we show that GB method gives exact results in
leading order terms.


title:
Scalable Semi-Supervised Learning over Networks using Nonsmooth Convex
  Optimization

abstract:
  We propose a scalable method for semi-supervised (transductive) learning from
massive network-structured datasets. Our approach to semi-supervised learning
is based on representing the underlying hypothesis as a graph signal with small
total variation. Requiring a small total variation of the graph signal
representing the underlying hypothesis corresponds to the central smoothness
assumption that forms the basis for semi-supervised learning, i.e., input
points forming clusters have similar output values or labels. We formulate the
learning problem as a nonsmooth convex optimization problem which we solve by
appealing to Nesterovs optimal first-order method for nonsmooth optimization.
We also provide a message passing formulation of the learning method which
allows for a highly scalable implementation in big data frameworks.


title: Inverting operations in operads

abstract:
  We construct a localization for operads with respect to one-ary operations
based on the Dwyer-Kan hammock localization. For an operad O and a sub-monoid
of one-ary operations W we associate an operad LO and a canonical map O to LO
which takes elements in W to homotopy invertible operations. Furthermore, we
give a functor from the category of O-algebras to the category of LO-algebras
satisfying an appropriate universal property.


title:
The assay of the hydration shell dynamics on the turnover of the active
  site of CF1-ATPase

abstract:
  Previous kinetic models had assumed that the reaction medium was reacting at
random and without a turnover associated to thermodynamics exchanges, with a
rigid active site on the enzyme. The experimental studies show that coupling
factor 1 (CF1) from spinach chloroplasts has latent ATPase activity, which
become expressed after heat-treatment and incubation with calcium. The
sigmoidal kinetics observed on the competitive effect of glycerol on water
saturating a protein, suggests that the role of the hydration shell in the
catalytic mechanism of the CF1-ATPase, modify the number of water molecules
associated with the conformational turnover required for active site activity.
It is assume that the water associated to the hydrophilic state of the enzyme
produces a fit-in of the substrate to form (ES), follow by the catalytic action
with product formation (EP). This one induces the dissociation of water and
increases the hydrophobic attractions between R-groups. The latter, becomes the
form of the enzyme interacting with water to form the dissociated free enzyme
(E) and free product (P). Glycerol dependent suppression of the water dynamics
on two interacting sites configuration shows a change in the
H-bond-configuration. The thermodynamics modeling requires an energy
expenditure of about 4kcal/mol per each H-bond in turnover. Glycerol determined
a turnover of 14 molecules of water released from the active sites to reach the
inactive form of the enzyme. The entropy generated by turnover of the fit-in
and -out substrate and product from the protein could be dissipated-out of the
enzyme-water system itself. Coupling with the surrounding water clusters allows
to recreate H-bonds. This should involve a decrease in the number of H-bonds
present in the clusters. These changes in the mass action capability of the
water clusters could eventually become dissipated through a cooling effect.


title: A Pareto scale-inflated outlier model and its Bayesian analysis

abstract:
  This paper develops a Pareto scale-inflated outlier model. This model is
intended for use when data from some standard Pareto distribution of interest
is suspected to have been contaminated with a relatively small number of
outliers from a Pareto distribution with the same shape parameter but with an
inflated scale parameter. The Bayesian analysis of this Pareto scale-inflated
outlier model is considered and its implementation using the Gibbs sampler is
discussed. The paper contains three worked illustrative examples, two of which
feature actual insurance claims data.


title: What is a graphon?

abstract:
  Graphons, short for graph functions, are limiting objects for sequences of
large, finite graphs with respect to the so-called cut metric. In this
expository piece, we define graphons, motivate them, and discuss how they
complete the space of finite graphs. We conclude by stating three theorems that
connect the finite world of graphs with the continuous world of graphons.


title:
On the chemical ladder of esters. Detection and formation of ethyl
  formate in the W51 e2 hot molecular core

abstract:
  The detection of organic molecules with increasing complexity and potential
biological relevance is opening the possibility to understand the formation of
the building blocks of life in the interstellar medium. One of the families of
molecules with astrobiological interest are the esters, whose simplest member,
methyl formate, is rather abundant in star-forming regions. The next step in
the chemical complexity of esters is ethyl formate, C$_2$H$_5$OCHO. Only two
detections of this species have been reported so far, which strongly limits our
understanding of how complex molecules are formed in the interstellar medium.
We have searched for ethyl formate towards the W51 e2 hot molecular core, one
of the most chemically rich sources in the Galaxy and one of the most promising
regions to study prebiotic chemistry, especially after the recent discovery of
the P$-$O bond, key in the formation of DNA. We have analyzed a spectral line
survey towards the W51 e2 hot molecular core, which covers 44 GHz in the 1, 2
and 3 mm bands, carried out with the IRAM 30m telescope. We report the
detection of the trans and gauche conformers of ethyl formate. A Local
Thermodynamic Equilibrium analysis indicates that the excitation temperature is
78$\pm$10 K and that the two conformers have similar source-averaged column
densities of (2.0$\pm$0.3)$\times$10$^{16}$ cm$^{-2}$ and an abundance of
$\sim$10$^{-8}$. We compare the observed molecular abundances of ethyl formate
with different competing chemical models based on grain surface and gas-phase
chemistry. We propose that grain-surface chemistry may have a dominant role in
the formation of ethyl formate (and other complex organic molecules) in hot
molecular cores, rather than reactions in the gas phase.


title: On restriction estimates for discrete quadratic surfaces

abstract:
  We obtain truncated restriction estimates of an unexpected form for discrete
surfaces \begin{align} S = \{\, ( n_1 , \dots , n_d , R( n_1 , \dots, n_d ) )
\,,\, n_i \in [-N,N] \cap \mathbb{Z} \,\}, \end{align} where $R$ is an
indefinite quadratic form with integer matrix.


title:
Approximating Cycles in Directed Graphs: Fast Algorithms for Girth and
  Roundtrip Spanners

abstract:
  The girth of a graph, i.e. the length of its shortest cycle, is a fundamental
graph parameter. Unfortunately all known algorithms for computing, even
approximately, the girth and girth-related structures in directed weighted
$m$-edge and $n$-node graphs require $\Omega(\min\{n^{\omega}, mn\})$ time (for
$2\leq\omega<2.373$). In this paper, we drastically improve these runtimes as
follows:
  * Multiplicative Approximations in Nearly Linear Time: We give an algorithm
that in $\widetilde{O}(m)$ time computes an $\widetilde{O}(1)$-multiplicative
approximation of the girth as well as an $\widetilde{O}(1)$-multiplicative
roundtrip spanner with $\widetilde{O}(n)$ edges with high probability (w.h.p).
  * Nearly Tight Additive Approximations: For unweighted graphs and any $\alpha
\in (0,1)$ we give an algorithm that in $\widetilde{O}(mn^{1 - \alpha})$ time
computes an $O(n^\alpha)$-additive approximation of the girth w.h.p, and
partially derandomize it. We show that the runtime of our algorithm cannot be
significantly improved without a breakthrough in combinatorial Boolean matrix
multiplication.
  Our main technical contribution to achieve these results is the first nearly
linear time algorithm for computing roundtrip covers, a directed graph
decomposition concept key to previous roundtrip spanner constructions.
Previously it was not known how to compute these significantly faster than
$\Omega(\min\{n^\omega, mn\})$ time. Given the traditional difficulty in
efficiently processing directed graphs, we hope our techniques may find further
applications.


title: Beau bounds for multicritical circle maps

abstract:
  Let $f: S^1\to S^1$ be a $C^3$ homeomorphism without periodic points having a
finite number of critical points of power-law type. In this paper we establish
real a-priori bounds, on the geometry of orbits of $f$, which are beau in the
sense of Sullivan, i.e. bounds that are asymptotically universal at small
scales. The proof of the beau bounds presented here is an adaptation, to the
multicritical setting, of the one given by the second author and de Melo, for
the case of a single critical point.


title: Socio-economic inequality and prospects of institutional Econophysics

abstract:
  Socio-economic inequality is measured using various indices. The Gini ($g$)
index, giving the overall inequality is the most commonly used, while the
recently introduced Kolkata ($k$) index gives a measure of $1-k$ fraction of
population who possess top $k$ fraction of wealth in the society. This article
reviews the character of such inequalities, as seen from a variety of data
sources, the apparent relationship between the two indices, and what toy models
tell us. These socio-economic inequalities are also investigated in the context
of man-made social conflicts or wars, as well as in natural disasters. Finally,
we forward a proposal for an international institution with sufficient fund for
visitors, where natural and social scientists from various institutions of the
world can come to discuss, debate and formulate further developments.


title: Computing proximal points of convex functions with inexact subgradients

abstract:
  Locating proximal points is a component of numerous minimization algorithms.
This work focuses on developing a method to find the proximal point of a convex
function at a point, given an inexact oracle. Our method assumes that exact
function values are at hand, but exact subgradients are either not available or
not useful. We use approximate subgradients to build a model of the objective
function, and prove that the method converges to the true prox-point within
acceptable tolerance. The subgradient $g_k$ used at each step $k$ is such that
the distance from $g_k$ to the true subdifferential of the objective function
at the current iteration point is bounded by some fixed $\varepsilon>0.$ The
algorithm includes a novel tilt-correct step applied to the approximate
subgradient.


title: Dark matter decay through gravity portals

abstract:
  Motivated by the fact that, so far, the whole body of evidence for dark
matter is of gravitational origin, we study the decays of dark matter into
Standard Model particles mediated by gravity portals, i.e., through nonminimal
gravitational interactions of dark matter. We investigate the decays in several
widely studied frameworks of scalar and fermionic dark matter where the dark
matter is stabilized in flat spacetime via global symmetries. We find that the
constraints on the scalar singlet dark matter candidate are remarkably strong
and exclude large regions of the parameter space, suggesting that an additional
stabilizing symmetry should be in place. In contrast, the scalar doublet and
the fermionic singlet candidates are naturally protected against too fast
decays by gauge and Lorentz symmetry, respectively. For a nonminimal coupling
parameter $\xi\sim {\cal{O}}(1)$, decays through the gravity portal are
consistent with observations if the dark matter mass is smaller than $\sim
10^5$ GeV, for the scalar doublet, and $\sim 10^6$ GeV, for the fermionic
singlet.


title:
Pure Gaussian states from quantum harmonic oscillator chains with a
  single local dissipative process

abstract:
  We study the preparation of entangled pure Gaussian states via reservoir
engineering. In particular, we consider a chain consisting of $(2\aleph+1)$
quantum harmonic oscillators where the central oscillator of the chain is
coupled to a single reservoir. We then completely parametrize the class of
$(2\aleph+1)$-mode pure Gaussian states that can be prepared by this type of
quantum harmonic oscillator chain. This parametrization allows us to determine
the steady-state entanglement properties of such quantum harmonic oscillator
chains.


title: Andreev Molecules in Semiconductor Nanowire Double Quantum Dots

abstract:
  Quantum simulation is a way to study unexplored Hamiltonians by mapping them
onto the assemblies of well-understood quantum systems such as ultracold atoms
in optical lattices, trapped ions or superconducting circuits. Semiconductor
nanostructures which form the backbone of classical computing hold largely
untapped potential for quantum simulation. In particular, chains of quantum
dots in semiconductor nanowires can be used to emulate one-dimensional
Hamiltonians such as the toy model of a topological p-wave superconductor. Here
we realize a building block of this model, a double quantum dot with
superconducting contacts, in an indium antimonide nanowire. In each dot,
tunnel-coupling to a superconductor induces Andreev bound states. We
demonstrate that these states hybridize to form the double-dot Andreev
molecular states. We establish the parity and the spin structure of Andreev
molecular levels by monitoring their evolution in electrostatic potential and
magnetic field. Understanding Andreev molecules is a key step towards building
longer chains which are predicted to generate Majorana bound states at the end
sites. Two superconducting quantum dots are already sufficient to test the
fusion rules of Majorana bound states, a milestone towards fault-tolerant
topological quantum computing.


title: MILC staggered conjugate gradient performance on Intel KNL

abstract:
  We review our work done to optimize the staggered conjugate gradient (CG)
algorithm in the MILC code for use with the Intel Knights Landing (KNL)
architecture. KNL is the second gener- ation Intel Xeon Phi processor. It is
capable of massive thread parallelism, data parallelism, and high on-board
memory bandwidth and is being adopted in supercomputing centers for scientific
research. The CG solver consumes the majority of time in production running, so
we have spent most of our effort on it. We compare performance of an MPI+OpenMP
baseline version of the MILC code with a version incorporating the QPhiX
staggered CG solver, for both one-node and multi-node runs.