title:
Exclusive vector meson photoproduction at the LHC and the FCC: A closer
  look on the final state

abstract:
  Over the past years the LHC experiments have reported experimental evidences
for processes associated to photon-photon and photon-hadron interactions,
showing their potential to investigate the production of low- and high-mass
systems in exclusive events. In the particular case of the photoproduction of
vector mesons, the experimental study of this final state is expected to shed
light on the description of the QCD dynamics at small values of the Bjorken-$x$
variable. In this paper we extend previous studies for the exclusive $J/\Psi$
and $\Upsilon$ photoproduction in $pp$ collisions based on the nonlinear QCD
dynamics by performing a detailed study of the final state distributions that
can be measured experimentally at the LHC and at the Future Circular Collider.
Predictions for the rapidity and transverse momentum distributions of the
vector mesons and of final-state dimuons are presented for $pp$ collisions at
$\sqrt{s} =$ 7, 13, and 100 TeV.


title:
Testing coupled dark energy models with their cosmological background
  evolution

abstract:
  We consider a cosmology in which dark matter and a quintessence scalar field
responsible for the acceleration of the Universe are allowed to interact.
Allowing for both conformal and disformal couplings, we perform a global
analysis of the constraints on our model using Hubble parameter measurements,
baryon acoustic oscillation distance measurements, and a Supernovae Type Ia
data set. We find that the additional disformal coupling relaxes the conformal
coupling constraints. Moreover we show that, at the background level, a
disformal interaction within the dark sector is preferred to both $\Lambda$CDM
and uncoupled quintessence, hence favouring interacting dark energy.


title: Symmetries and ergodic properties in quantum probability

abstract:
  We deal with the general structure of (noncommutative) stochastic processes
by using the standard techniques of Operator Algebras. Any stochastic process
is associated to a state on a universal object, i.e. the free product
$C^*$-algebra in a natural way. In this setting one recovers the classical
(i.e. commutative) probability scheme and many others, like those associated to
the Monotone, Boolean and the $q$-deformed canonical commutation relations
including the Bose/Fermi and Boltzmann cases. Natural symmetries like
stationarity and exchangeability, as well as the ergodic properties of the
stochastic processes are reviewed in detail for many interesting cases arising
from Quantum Physics and Probability.


title:
A 50/50 electronic beam splitter in graphene nanoribbons as a building
  block for electron optics

abstract:
  Based on the investigation of the multi-terminal conductance of a system
composed of two graphene nanoribbons, in which one is on top of the other and
rotated by 60 degrees, we propose a setup for a 50/50 electronic beam splitter
that neither requires large magnetic fields nor ultra low temperatures. Our
findings are based on an atomistic tight-binding description of the system and
on the Green's function method to compute the Landauer conductance. We
demonstrate that this system acts as a perfect 50/50 electronic beam splitter,
in which its operation can be switched on and off by varying the doping (Fermi
energy). We show that this device is robust against thermal fluctuations and
long range disorder, as zigzag valley chiral states of the nanoribbons are
protected against backscattering. We suggest that the proposed device can be
applied as the fundamental element of the Hong-Ou-Mandel interferometer, as
well as a building block of many devices in electron optics.


title:
Reverse engineering nuclear properties from rare earth abundances in the
  $r$ process

abstract:
  The bulk of the rare earth elements are believed to be synthesized in the
rapid neutron capture process or $r$ process of nucleosynthesis. The solar
$r$-process residuals show a small peak in the rare earths around $A\sim 160$,
which is proposed to be formed dynamically during the end phase of the $r$
process by a pileup of material. This abundance feature is of particular
importance as it is sensitive to both the nuclear physics inputs and the
astrophysical conditions of the main $r$ process. We explore the formation of
the rare earth peak from the perspective of an inverse problem, using Monte
Carlo studies of nuclear masses to investigate the unknown nuclear properties
required to best match rare earth abundance sector of the solar isotopic
residuals. When nuclear masses are changed, we recalculate the relevant
$\beta$-decay properties and neutron capture rates in the rare earth region.
The feedback provided by this observational constraint allows for the reverse
engineering of nuclear properties far from stability where no experimental
information exists. We investigate a range of astrophysical conditions with
this method and show how these lead to different predictions in the nuclear
properties influential to the formation of the rare earth peak. We conclude
that targeted experimental campaigns in this region will help to resolve the
type of conditions responsible for the production of the rare earth nuclei, and
will provide new insights into the longstanding problem of the astrophysical
site(s) of the $r$ process.


title:
Precision ESR Measurements of Transverse Anisotropy in the
  Single-molecule Magnet Ni$_4$

abstract:
  We present a method for precisely measuring the tunnel splitting in
single-molecule magnets using electron-spin resonance, and use these
measurements to precisely and independently determine the underlying transverse
anisotropy parameter, given a certain class of transitions. By diluting samples
of the SMM Ni$_4$ via co-crystallization in a diamagnetic isostructural
analogue we obtain markedly narrower resonance peaks than are observed in
undiluted samples. Using custom loop-gap resonators we measure the transitions
at several frequencies, allowing a precise determination of the tunnel
splitting. Because the transition under investigation occurs at zero field, and
arises due to a first-order perturbation from the transverse anisotropy, we can
determine the magnitude of this anisotropy independent of any other Hamiltonian
parameters. This method can be applied to other SMMs with tunnel splittings
arising from first-order transverse anisotropy perturbations.


title: Jump Events in a 3D Edwards-Anderson Spin Glass

abstract:
  The statistical properties of infrequent particle displacements, greater than
a certain distance, is known as jump dynamics in the context of structural
glass formers. We generalize the concept of jump to the case of a spin glass,
by dividing the system in small boxes, and considering infrequent cooperative
spin flips in each box. Jumps defined this way share similarities with jumps in
structural glasses. We perform numerical simulations for the 3D
Edwards-Anderson model, and study how the properties of these jumps depend on
the waiting time after a quench. Similar to the results for structural glasses,
we find that while jump frequency depends strongly on time, jump duration and
jump length are roughly stationary. At odds with some results reported on
studies of structural glass formers, at long enough times, the rest time
between jumps varies as the inverse of jump frequency. We give a possible
explanation for this discrepancy. We also find that our results are
qualitatively reproduced by a fully-connected trap model.


title:
An Efficient Optimal Planning and Control Framework For Quadrupedal
  Locomotion

abstract:
  In this paper, we present an efficient Dynamic Programing framework for
optimal planning and control of legged robots. First we formulate this problem
as an optimal control problem for switched systems. Then we propose a
multi--level optimization approach to find the optimal switching times and the
optimal continuous control inputs. Through this scheme, the decomposed
optimization can potentially be done more efficiently than the combined
approach. Finally, we present a continuous-time constrained LQR algorithm which
simultaneously optimizes the feedforward and feedback controller with $O(n)$
time-complexity. In order to validate our approach, we show the performance of
our framework on a quadrupedal robot. We choose the Center of Mass dynamics and
the full kinematic formulation as the switched system model where the switching
times as well as the contact forces and the joint velocities are optimized for
different locomotion tasks such as gap crossing, walking and trotting.


title:
A Legendre-Fourier spectral method with exact conservation laws for the
  Vlasov-Poisson system

abstract:
  We present the design and implementation of an L2-stable spectral method for
the discretization of the Vlasov- Poisson model of a collisionless plasma in
one space and velocity dimension. The velocity and space dependence of the
Vlasov equation are resolved through a truncated spectral expansion based on
Legendre and Fourier basis functions, respectively. The Poisson equation, which
is coupled to the Vlasov equation, is also resolved through a Fourier
expansion. The resulting system of ordinary differential equation is
discretized by the implicit second-order accurate Crank-Nicolson time
discretization. The non-linear dependence between the Vlasov and Poisson
equations is iteratively solved at any time cycle by a Jacobian-Free
Newton-Krylov method. In this work we analyze the structure of the main
conservation laws of the resulting Legendre-Fourier model, e.g., mass,
momentum, and energy, and prove that they are exactly satisfied in the
semi-discrete and discrete setting. The L2-stability of the method is ensured
by discretizing the boundary conditions of the distribution function at the
boundaries of the velocity domain by a suitable penalty term. The impact of the
penalty term on the conservation properties is investigated theoretically and
numerically. An implementation of the penalty term that does not affect the
conservation of mass, momentum and energy, is also proposed and studied. A
collisional term is introduced in the discrete model to control the
filamentation effect, but does not affect the conservation properties of the
system. Numerical results on a set of standard test problems illustrate the
performance of the method.


title:
Twisted Supersymmetry in a Deformed Wess-Zumino Model in (2+1)
  Dimensions

abstract:
  Non-anticommutative deformations have been studied in the context of
supersymmetry (SUSY) in three and four space-time dimensions, and the general
picture is that highly nontrivial to deform supersymmetry in a way that still
preserves some of its important properties, both at the formal algebraic level
(e.g., preserving the associativity of the deformed theory) as well as at the
physical level (e.g., maintaining renormalizability). The Hopf algebra
formalism allows the definition of algebraically consistent deformations of
SUSY, but this algebraic consistency does not guarantee that physical models
build upon these structures will be consistent from the physical point of view.
We will investigate a deformation induced by a Drinfel'd twist of the ${\cal
N}=1$ SUSY algebra in three space-time dimensions. The use of the Hopf algebra
formalism allows the construction of deformed ${\cal N}=1$ SUSY algebras that
should still preserve a deformed version of supersymmetry. We will construct
the simplest deformed version of the Wess-Zumino model in this context, but we
will show that despite the consistent algebraic structure, the model in
question is not invariant under SUSY transformation and is not renormalizable.
We will comment on the relation of these results with previous ones discussed
in the literature regarding similar four-dimensional constructions.


title:
Technical Report: Graph-Structured Sparse Optimization for Connected
  Subgraph Detection

abstract:
  Structured sparse optimization is an important and challenging problem for
analyzing high-dimensional data in a variety of applications such as
bioinformatics, medical imaging, social networks, and astronomy. Although a
number of structured sparsity models have been explored, such as trees, groups,
clusters, and paths, connected subgraphs have been rarely explored in the
current literature. One of the main technical challenges is that there is no
structured sparsity-inducing norm that can directly model the space of
connected subgraphs, and there is no exact implementation of a projection
oracle for connected subgraphs due to its NP-hardness. In this paper, we
explore efficient approximate projection oracles for connected subgraphs, and
propose two new efficient algorithms, namely, Graph-IHT and Graph-GHTP, to
optimize a generic nonlinear objective function subject to connectivity
constraint on the support of the variables. Our proposed algorithms enjoy
strong guarantees analogous to several current methods for sparsity-constrained
optimization, such as Projected Gradient Descent (PGD), Approximate Model
Iterative Hard Thresholding (AM-IHT), and Gradient Hard Thresholding Pursuit
(GHTP) with respect to convergence rate and approximation accuracy. We apply
our proposed algorithms to optimize several well-known graph scan statistics in
several applications of connected subgraph detection as a case study, and the
experimental results demonstrate that our proposed algorithms outperform
state-of-the-art methods.


title:
Separating Double-Beta Decay Events from Solar Neutrino Interactions in
  a Kiloton-Scale Liquid Scintillator Detector By Fast Timing

abstract:
  We present a technique for separating nuclear double beta decay
($\beta\beta$-decay) events from background neutrino interactions due to
$^{8}$B decays in the sun. This background becomes dominant in a kiloton-scale
liquid-scintillator detector deep underground and is usually considered as
irreducible due to an overlap in deposited energy with the signal. However,
electrons from 0$\nu\beta\beta$-decay often exceed the Cherenkov threshold in
liquid scintillator, producing photons that are prompt and correlated in
direction with the initial electron direction. The use of large-area fast
photodetectors allows some separation of these prompt photons from delayed
isotropic scintillation light and, thus, the possibility of reconstructing the
event topology. Using a simulation of a 6.5~m radius liquid scintillator
detector with 100~ps resolution photodetectors, we show that a spherical
harmonics analysis of early-arrival light can discriminate between
0$\nu\beta\beta$-decay signal and $^{8}$B solar neutrino background events on a
statistical basis. Good separation will require the development of a slow
scintillator with a 5 nsec risetime.


title:
Antiferromagnetic THz-frequency Josephson-like Oscillator Driven by Spin
  Current

abstract:
  The development of compact and tunable room temperature sources of coherent
THz-frequency signals would open a way for numerous new applications. The
existing approaches to THz-frequency generation based on superconductor
Josephson junctions (JJ), free electron lasers, and quantum cascades require
cryogenic temperatures or/and complex setups, preventing the miniaturization
and wide use of these devices. We demonstrate theoretically that a bi-layer of
a heavy metal (Pt) and a bi-axial antiferromagnetic (AFM) dielectric (NiO) can
be a source of a coherent THz signal. A spin-current flowing from a
DC-current-driven Pt layer and polarized along the hard AFM anisotropy axis
excites a non-uniform in time precession of magnetizations sublattices in the
AFM, due to the presence of a weak easy-plane AFM anisotropy. The frequency of
the AFM oscillations varies in the range of 0.1-2.0 THz with the driving
current in the Pt layer from $10^8\text{A}/\text{cm}^2$ to
$10^9\text{A}/\text{cm}^2$. The THz-frequency signal from the AFM with the
amplitude exceeding 1 V/cm is picked up by the inverse spin-Hall effect in Pt.
The operation of a room-temperature AFM THz-frequency oscillator is similar to
that of a cryogenic JJ oscillator, with the energy of the easy-plane magnetic
anisotropy playing the role of the Josephson energy.


title:
Transversality and super-rigidity for multiply covered holomorphic
  curves

abstract:
  We develop new techniques to study regularity questions for moduli spaces of
pseudoholomorphic curves that are multiply covered. Among the main results, we
show that unbranched multiple covers of closed holomorphic curves are
generically regular, and simple index zero curves in dimensions greater than
four are generically super-rigid, implying e.g. that the Gromov-Witten
invariants of Calabi-Yau 3-folds reduce to sums of local invariants for finite
sets of embedded curves. We also establish partial results on super-rigidity in
dimension four and regularity of branched covers, and briefly discuss the
outlook for bifurcation analysis. The proofs are based on a general
stratification result for moduli spaces of multiple covers, framed in terms of
a representation-theoretic splitting of Cauchy-Riemann operators with
symmetries.


title: A pragmatical access to the viscous flow

abstract:
  The paper derives a relation for the viscosity of undercooled liquids on the
basis of the pragmatical model concept of Eshelby relaxations with a finite
lifetime. From accurate shear relaxation data in the literature, one finds that
slightly less than half of the internal stresses relax directly via single
Eshelby relaxations; the larger part dissolves at the terminal lifetime, which
is a combined effect of many Eshelby relaxations.


title: Structured Inference Networks for Nonlinear State Space Models

abstract:
  Gaussian state space models have been used for decades as generative models
of sequential data. They admit an intuitive probabilistic interpretation, have
a simple functional form, and enjoy widespread adoption. We introduce a unified
algorithm to efficiently learn a broad class of linear and non-linear state
space models, including variants where the emission and transition
distributions are modeled by deep neural networks. Our learning algorithm
simultaneously learns a compiled inference network and the generative model,
leveraging a structured variational approximation parameterized by recurrent
neural networks to mimic the posterior distribution. We apply the learning
algorithm to both synthetic and real-world datasets, demonstrating its
scalability and versatility. We find that using the structured approximation to
the posterior results in models with significantly higher held-out likelihood.


title:
Bacterial Foraging Optimized STATCOM for Stability Assessment in Power
  System

abstract:
  This paper presents a study of improvement in stability in a single machine
connected to infinite bus (SMIB) power system by using static compensator
(STATCOM). The gains of Proportional-Integral-Derivative (PID) controller in
STATCOM are being optimized by heuristic technique based on Particle swarm
optimization (PSO). Further, Bacterial Foraging Optimization (BFO) as an
alternative heuristic method is also applied to select optimal gains of PID
controller. The performance of STATCOM with the above soft-computing techniques
are studied and compared with the conventional PID controller under various
scenarios. The simulation results are accompanied with performance indices
based quantitative analysis. The analysis clearly signifies the robustness of
the new scheme in terms of stability and voltage regulation when compared with
conventional PID.


title:
A multi-scale model for electrokinetic transport in networks of
  micro-scale and nano-scale pores

abstract:
  We present an efficient and robust numerical model for simulation of
electrokinetic phenomena in porous networks over a wide range of applications
including energy conversion, desalination, and lab-on-a-chip systems. Coupling
between fluid flow and ion transport in these networks is governed by the
Poisson-Nernst-Planck-Stokes equations. These equations describe a wide range
of transport phenomena that can interact in complex and highly nonlinear ways
in networks involving multiple pores with variable properties. Capturing these
phenomena by direct simulation of the governing equations in multiple
dimensions is prohibitively expensive. We present here a reduced order
computational model that treats a network of many pores via solutions to 1D
equations. Assuming that each pore in the network is long and thin, we derive a
1D model describing the transport in pore's longitudinal direction. We take
into account the non-uniformity of potential and ion concentration profiles
across the pore cross-section in the form of area-averaged coefficients in
different flux terms representing fluid flow, electric current, and ion fluxes.
Distinct advantages of the present framework include: a fully conservative
discretization, fully bounded tabulated area-averaged coefficients without any
singularity in the limit of infinitely thick electric double layers (EDLs), a
flux discretization that exactly preserves equilibrium conditions, and
extension to general network of pores with multiple intersections. By
considering a hierarchy of canonical problems with increasing complexity, we
demonstrate that the developed framework can capture a wide range of phenomena.
Example demonstrations include, prediction of osmotic pressure built up in thin
pores subject to concentration gradient, propagation of deionization shocks and
induced recirculations for intersecting pores with varying properties.


title: Electronics for the STEREO experiment

abstract:
  The STEREO experiment, aiming to probe short baseline neutrino oscillations
by precisely measuring reactor anti-neutrino spectrum, is currently under
installation. It is located at short distance from the compact research reactor
core of the Institut Laue-Langevin, Grenoble, France. Dedicated electronics,
hosted in a single $\mu$TCA crate, were designed for this experiment. In this
article, the electronics requirements, architecture and the performances
achieved are described. It is shown how intrinsic Pulse Shape Discrimination
properties of the liquid scintillator are preserved and how custom adaptable
logic is used to improve the muon veto efficiency.


title:
Energy consistent framework for continuously evolving 3D crack
  propagation

abstract:
  This paper presents a formulation for brittle fracture in 3D elastic solids
within the context of configurational mechanics. The local form of the first
law of thermodynamics provides a condition for equilibrium of the crack front.
The direction of the crack propagation is shown to be given by the direction of
the configurational forces on the crack front that maximise the local
dissipation. The evolving crack front is continuously resolved by the finite
element mesh, without the need for face splitting or the use of enrichment
techniques. A monolithic solution strategy is adopted, solving simultaneously
for both the material displacements (i.e. crack extension) and the spatial
displacements, is adopted. In order to trace the dissipative loading path, an
arc-length procedure is developed that controls the incremental crack area
growth. In order to maintain mesh quality, smoothing of the mesh is undertaken
as a continuous process, together with face flipping, node merging and edge
splitting where necessary. Hierarchical basis functions of arbitrary polynomial
order are adopted to increase the order of approximation without the need to
change the finite element mesh. Performance of the formulation is demonstrated
by means of three representative numerical simulations, demonstrating both
accuracy and robustness.


title: Time Operator in Relativistic Quantum Mechanics

abstract:
  It is first shown that the Dirac's equation in a relativistic frame could be
modified to allow discrete time, in agreement to a recently published upper
bound. Next, an exact self-adjoint $4\times 4$ relativistic time operator for
spin-$\frac{1}{2}$ particles is found and the time eigenstates for the
non-relativistic case are obtained and discussed. Results confirm the quantum
mechanical speculation that particles can indeed occupy negative energy levels
with vanishingly small but non-zero probablity, contrary to the general
expectation from classical physics. Hence, Wolfgang Pauli's objection regarding
the existence of a self-adjoint time operator is fully resolved. It is shown
that using the time operator, a bosonic field referred here to as energons may
be created, whose number state representations in non-relativistic momentum
space can be explicitly found.


title: Projected Sensitivity of the SuperCDMS SNOLAB experiment

abstract:
  SuperCDMS SNOLAB will be a next-generation experiment aimed at directly
detecting low-mass (< 10 GeV/c$^2$) particles that may constitute dark matter
by using cryogenic detectors of two types (HV and iZIP) and two target
materials (germanium and silicon). The experiment is being designed with an
initial sensitivity to nuclear recoil cross sections ~ 1 x 10$^{-43}$ cm$^2$
for a dark matter particle mass of 1 GeV/c$^2$, and with capacity to continue
exploration to both smaller masses and better sensitivities. The phonon
sensitivity of the HV detectors will be sufficient to detect nuclear recoils
from sub-GeV dark matter. A detailed calibration of the detector response to
low energy recoils will be needed to optimize running conditions of the HV
detectors and to interpret their data for dark matter searches. Low-activity
shielding, and the depth of SNOLAB, will reduce most backgrounds, but
cosmogenically produced $^{3}$H and naturally occurring $^{32}$Si will be
present in the detectors at some level. Even if these backgrounds are x10
higher than expected, the science reach of the HV detectors would be over three
orders of magnitude beyond current results for a dark matter mass of 1
GeV/c$^2$. The iZIP detectors are relatively insensitive to variations in
detector response and backgrounds, and will provide better sensitivity for dark
matter particle masses (> 5 GeV/c$^2$). The mix of detector types (HV and
iZIP), and targets (germanium and silicon), planned for the experiment, as well
as flexibility in how the detectors are operated, will allow us to maximize the
low-mass reach, and understand the backgrounds that the experiment will
encounter. Upgrades to the experiment, perhaps with a variety of
ultra-low-background cryogenic detectors, will extend dark matter sensitivity
down to the "neutrino floor", where coherent scatters of solar neutrinos become
a limiting background.


title: From Type II string theory towards BSM/dark sector physics

abstract:
  Four-dimensional compactifications of string theory provide a controlled set
of possible gauge representations accounting for BSM particles and dark sector
components. In this review, constraints from perturbative Type II string
compactifications in the geometric regime are discussed in detail and then
compared to results from heterotic string compactifications and
non-perturbative/non-geometric corners. As a prominent example, an open string
realization of the QCD axion is presented. The status of deriving the
associated low-energy effective action in four dimensions is discussed and open
avenues of major phenomenological importance are highlighted. As examples, a
mechanism of closed string moduli stabilization by D-brane backreaction as well
as one-loop threshold corrections to the gauge couplings and balancing a low
string scale $M_{\text{string}}$ with unisotropic compact dimensions are
discussed together with implications on potential future new physics
observations. For illustrative purposes, an explicit example of a globally
consistent D6-brane model with MSSM-like spectrum on $T^6/(\mathbb{Z}_2 \times
\mathbb{Z}_6 \times \Omega {\cal R})$ is presented.


title: Reverberation Mapping of Optical Emission Lines in Five Active Galaxies

abstract:
  We present the first results from an optical reverberation mapping campaign
executed in 2014, targeting the active galactic nuclei (AGN) MCG+08-11-011, NGC
2617, NGC 4051, 3C 382, and Mrk 374. Our targets have diverse and interesting
observational properties, including a "changing look" AGN and a broad-line
radio galaxy. Based on continuum-H$\beta$ lags, we measure black hole masses
for all five targets. We also obtain H$\gamma$ and He{\sc ii}\,$\lambda 4686$
lags for all objects except 3C 382. The He{\sc ii}\,$\lambda 4686$ lags
indicate radial stratification of the BLR, and the masses derived from
different emission lines are in general agreement. The relative responsivities
of these lines are also in qualitative agreement with photoionization models.
These spectra have extremely high signal-to-noise ratios (100--300 per pixel)
and there are excellent prospects for obtaining velocity-resolved reverberation
signatures.


title: Analyzing the CP Nature of a New Scalar Particle via S->Zh Decay

abstract:
  Scalar particles $S$ which are singlets under the Standard Model gauge group
are generic features of many models of fundamental physics, in particular as
possible mediators to a hidden sector. We show that the decay $S\to Zh$
provides a powerful probe of the CP nature of the scalar, because it is allowed
only if $S$ has CP-odd interactions. We perform a model-independent analysis of
this decay using an effective Lagrangian and compute the relevant Wilson
coefficients arising from integrating out heavy fermions to one-loop order.


title: Super-Planckian Spatial Field Variations and Quantum Gravity

abstract:
  We study scenarios where a scalar field has a spatially varying vacuum
expectation value such that the total field variation is super-Planckian. We
focus on the case where the scalar field controls the coupling of a U(1) gauge
field, which allows us to apply the Weak Gravity Conjecture to such
configurations. We show that this leads to evidence for a conjectured property
of quantum gravity that as a scalar field variation in field space asymptotes
to infinity there must exist an infinite tower of states whose mass decreases
as an exponential function of the scalar field variation. We determine the rate
at which the mass of the states reaches this exponential behaviour showing that
it occurs quickly after the field variation passes the Planck scale.


title: Emergent Spacetime for Quantum Gravity

abstract:
  We emphasize that noncommutative (NC) spacetime necessarily implies emergent
spacetime if spacetime at microscopic scales should be viewed as NC. In order
to understand NC spacetime correctly, we need to deactivate the thought
patterns that we have installed in our brains and taken for granted for so many
years. Emergent spacetime allows a background-independent formulation of
quantum gravity that will open a new perspective to resolve the notorious
problems in theoretical physics such as the cosmological constant problem,
hierarchy problem, dark energy, dark matter, and cosmic inflation.


title: Cosmic Inflation from Emergent Spacetime Picture

abstract:
  We argue that the emergent spacetime picture admits a background-independent
formulation of cosmic inflation. The inflation in this picture corresponds to
the dynamical emergence of spacetime while the conventional inflation is simply
an (exponential) expansion of a preexisting spacetime owing to the vacuum
energy carried by an inflaton field. We show that the cosmic inflation arises
as a time-dependent solution of the matrix quantum mechanics describing the
dynamical process of Planck energy condensate in vacuum without introducing any
inflaton field as well as an {\it ad hoc} inflation potential. Thus the
emergent spacetime picture realizes a background-independent description of the
inflationary universe which has a sufficiently elegant and explanatory power to
defend the integrity of physics against the multiverse hypothesis.


title:
The compact H$\alpha$ emitting regions of the Herbig Ae/Be stars HD
  179218 and HD 141569 from CHARA spectro-interferometry

abstract:
  This work presents CHARA/VEGA H$\alpha$ spectro-interferometry (R ~ 6000, and
$\lambda$/2B ~ 1 mas) of HD 179218 and HD 141569, doubling the sample of Herbig
Ae/Be (HAeBe) stars for which this type of observations is available so far.
The observed H$\alpha$ emission is spatially unresolved, indicating that the
size of the H$\alpha$ emitting region is smaller than ~ 0.21 and 0.12 au for HD
179218 and HD 141529 (~ 15 and 16 R*, respectively). This is smaller than for
the two other HAeBes previously observed with the same instrumentation. Two
different scenarios have been explored in order to explain the compact line
emitting regions. A hot, several thousand K, blackbody disc is consistent with
the observations of HD 179218 and HD 141569. Magnetospheric accretion (MA) is
able to reproduce the bulk of the H$\alpha$ emission shown by HD 179218,
confirming previous estimates from MA shock modelling with a mass accretion
rate of 10^-8 Msun/yr, and an inclination to the line of sight between 30 and
50 degr. The H$\alpha$ profile of HD 141569 cannot be fitted from MA due to the
high rotational velocity of this object. Putting the CHARA sample together, a
variety of scenarios is required to explain the H$\alpha$ emission in HAeBe
stars -compact or extended, discs, accretion, and winds-, in agreement with
previous Br$\gamma$ spectro-interferometric observations.


title:
The information content of stellar halos: Stellar population gradients
  and accretion histories in early-type Illustris galaxies

abstract:
  Long dynamical timescales in the outskirts of galaxies preserve the
information content of their accretion histories, for example in the form of
stellar population gradients. We present a detailed analysis of the stellar
halo properties of a statistically representative sample of early-type galaxies
from the Illustris simulation and show that stellar population gradients at
large radii can indeed be used to infer basic properties of galactic accretion
histories. We measure metallicity, age, and surface-brightness profiles in
quiescent Illustris galaxies ranging from $\mathrm{M}_\star = 10^{10} - 2\times
10^{12}\;\mathrm{M}_\odot$ and show that they are in reasonable agreement with
observations. At fixed mass, galaxies that accreted little of their stellar
halo material tend to have steeper metallicity and surface-brightness profiles
between 2 - 4 effective radii (R$_e$) than those with larger accreted
fractions. Profiles of metallicity and surface-brightness in the stellar halo
typically flatten from z = 1 to the present. This suggests that the accretion
of stars into the stellar halo tends to flatten metallicity and
surface-brightness profiles, a picture which is supported by the tight
correlation between the two gradients in the stellar halo. We find no
statistical evidence of additional information content related to accretion
histories in stellar halo metallicity profiles beyond what is contained in
surface-brightness profiles. Age gradients in the stellar halo do not appear to
be sensitive to galactic accretion histories, and none of the stellar
population gradients studied are strongly correlated with the mean merger
mass-ratio. Future observations that reach large radii outside galaxies will
have the best potential to constrain galactic accretion histories.


title:
Beyond the Boost: Measuring the intrinsic dipole of the CMB using the
  spectral distortions of the monopole and quadrupole

abstract:
  We present a general framework for accurate spectral modeling of the low
multipoles of the cosmic microwave background (CMB) as observed in a boosted
frame. In particular, we demonstrate how spectral measurements of the low
multipoles can be used to separate the motion-induced dipole of the CMB from a
possible intrinsic dipole component. In a moving frame, the leakage of an
intrinsic dipole moment into the CMB monopole and quadrupole induces spectral
distortions with distinct frequency functions that respectively peak at 337 GHz
and 276 GHz. The leakage into the quadrupole moment also induces a geometrical
distortion to the spatial morphology of this mode. The combination of these
effects can be used to lift the degeneracy between the motion-induced dipole
and any intrinsic dipole that the CMB might possess. Assuming the current
peculiar velocity measurements, the leakage of an intrinsic dipole with an
amplitude of $\Delta T = 30\mu$K into the monopole and quadrupole moments will
be detectable by a PIXIE--like experiment at $\sim 40~$nK ($2.5\sigma$) and
$\sim 130~$nK ($11\sigma$) level at their respective peak frequencies.


title: Effects of Dimensionality on Pair-Instability Supernova Explosions

abstract:
  Since the emergence of the new class of extremely bright transients,
super-luminous supernovae (SLSNe), three main mechanisms to power their light
curves (LCs) have been discussed. They are the spin-down of a magnetar,
interaction with circumstellar material, and the decay of large amounts of
radioactive nickel in pair-instability supernovae (PISNe). Given the high
degree of diversity seen within the class, it is possible that all three
mechanisms are at work. PISN models can be self- consistently simulated from
the main sequence phase of very massive stars (VMS) through to their explosion.
These models robustly predict large amounts of radioactive nickel and thus very
luminous SN events. However, PISN model LCs evolve more slowly than even the
slowest evolving SLSNe. Multidimensional effects on the ejecta structure,
specifically the mixing of radioactive nickel out to large radii, could
alleviate this discrepancy with observation. Here we explore the
multidimensional effects on the LC evolution by simulating the explosion phase
in 1D, 2D, and 3D. We find that the ejecta from the multidimensional
simulations have slightly shallower abundance gradients due to mixing at shell
boundaries. We compute synthetic LCs whose shapes show no discernible
differences due to the multidimensional effects.


title: On Optimal Latency of Communications

abstract:
  In this paper we investigate the optimal latency of communications. Focusing
on fixed rate communication without any feedback channel, this paper
encompasses low-latency strategies with which one hop and multi-hop
communication issues are treated from an information theoretic perspective. By
defining the latency as the time required to make decisions, we prove that if
short messages can be transmitted in parallel Gaussian channels, for example,
via orthogonal frequency-division multiplexing (OFDM)-like signals, there
exists an optimal low-latency strategy for every code. This can be achieved via
early-detection schemes or asynchronous detections. We first provide the
optimal achievable latency in additive white Gaussian noise (AWGN) channels for
every channel code given a probability block error $\epsilon$. This can be
obtained via sequential ratio tests or a "genie" aided, \textit{e.g}.
error-detecting codes. Results demonstrate the effectiveness of the approach.
Next, we show how early-detection can be effective with OFDM signals while
maintaining its spectral efficiency via random coding or pre-coding random
matrices. Finally, we explore the optimal low-latency strategy in multi-hop
relaying schemes. For amplify-and-forward (AF) and decode-and-forward (DF)
relaying schemes there exist an optimal achievable latency. In particular, we
first show that there exist a better low-latency strategy, for which AF relays
could transmit while receiving. This can be achieved by using amplify and
forward combined with early detection.


title: An iterative method for spherical bounces

abstract:
  We develop a new iterative method for finding approximate solutions for
spherical bounces associated with the decay of the false vacuum in scalar field
theories. The method works for any generic potential in any number of
dimensions, contains Coleman's thin-wall approximation as its first iteration,
and greatly improves its accuracy by including higher order terms.


title: Metasurface Freeform Nanophotonics

abstract:
  Freeform optics aims to expand the toolkit of optical elements by allowing
for more complex phase geometries beyond rotational symmetry. Complex,
asymmetric curvatures are employed to enhance the performance of optical
components while minimizing their weight and size. Unfortunately, these
asymmetric forms are often difficult to manufacture at the nanoscale with
current technologies. Metasurfaces are planar sub-wavelength structures that
can control the phase, amplitude, and polarization of incident light, and can
thereby mimic complex geometric curvatures on a flat, wavelength-scale thick
surface. We present a methodology for designing analogues of freeform optics
using a low contrast dielectric metasurface platform for operation at visible
wavelengths. We demonstrate a cubic phase plate with a point spread function
exhibiting enhanced depth of field over 300 {\mu}m along the optical axis with
potential for performing metasurface-based white light imaging, and an Alvarez
lens with a tunable focal length range of over 2.5 mm with 100 {\mu}m of total
mechanical displacement. The adaptation of freeform optics to a sub-wavelength
metasurface platform allows for the ultimate miniaturization of optical
components and offers a scalable route toward implementing near-arbitrary
geometric curvatures in nanophotonics.


title: Bianchi-I cosmology from causal thermodynamics

abstract:
  We investigate diagonal Bianchi-I spacetimes in the presence of viscous
fluids by using the shear and the anisotropic pressure components as the basic
variables, where the viscosity is driven by the (second-order) causal
thermodynamics. A few exact solutions are presented, among which we mention the
anisotropic versions of de Sitter/anti-de Sitter geometries as well as an
asymptotically isotropic spacetime presenting an effective constant cosmic
acceleration without any cosmological constant. The qualitative analysis of the
solutions for barotropic fluids with linear equations of state suggests that
the behaviour is quite general.


title: Feller property of the multiplicative coalescent with linear deletion

abstract:
  We modify the definition of Aldous' multiplicative coalescent process and
introduce the multiplicative coalescent with linear deletion (MCLD). A state of
this process is a square-summable decreasing sequence of cluster sizes. Pairs
of clusters merge with a rate equal to the product of their sizes and clusters
are deleted with a rate linearly proportional to their size. We prove that the
MCLD is a Feller process. This result is a key ingredient in the description of
scaling limits of the evolution of component sizes of the mean field frozen
percolation model and the so-called rigid representation of such scaling
limits.


title: A Stronger Theorem Against Macro-realism

abstract:
  Macro-realism is the position that certain "macroscopic" observables must
always possess definite values: e.g. the table is in some definite position,
even if we don't know what that is precisely. The traditional understanding is
that by assuming macro-realism one can derive the Leggett-Garg inequalities,
which constrain the possible statistics from certain experiments. Since quantum
experiments can violate the Leggett-Garg inequalities, this is taken to rule
out the possibility of macro-realism in a quantum universe. However, recent
analyses have exposed loopholes in the Leggett-Garg argument, which allow many
types of macro-realism to be compatible with quantum theory and hence violation
of the Leggett-Garg inequalities. This paper takes a different approach to
ruling out macro-realism and the result is a no-go theorem for macro-realism in
quantum theory that is stronger than the Leggett-Garg argument. This approach
uses the framework of ontological models: an elegant way to reason about
foundational issues in quantum theory which has successfully produced many
other recent results, such as the PBR theorem.


title:
The locally adapted patch finite element method for interface problems
  on triangular meshes

abstract:
  We present a locally adapted parametric finite element method for interface
problems. For this adapted finite element method we show optimal convergence
for elliptic interface problems with a discontinuous diffusion parameter. The
method is based on the adaption of macro elements where a local basis
represents the interface. The macro elements are independent of the interface
and can be cut by the interface. A macro element which is a triangle in the
triangulation is divided into four subtriangles. On these subtriangles, the
basis functions of the macro element are interpreted as linear functions. The
position of the vertices of these subtriangles is determined by the location of
the interface in the case a macro element is cut by the interface. Quadrature
is performed on the subtriangles via transformations to a reference element.
Due to the locality of the method, its use is well suited on distributed
architectures.


title:
A Study of Revenue Cost Dynamics in Large Data Centers: A Factorial
  Design Approach

abstract:
  Revenue optimization of large data centers is an open and challenging
problem. The intricacy of the problem is due to the presence of too many
parameters posing as costs or investment. This paper proposes a model to
optimize the revenue in cloud data center and analyzes the model, revenue and
different investment or cost commitments of organizations investing in data
centers. The model uses the Cobb-Douglas production function to quantify the
boundaries and the most significant factors to generate the revenue. The
dynamics between revenue and cost is explored by designing an experiment (DoE)
which is an interpretation of revenue as function of cost/investment as factors
with different levels/fluctuations. Optimal elasticities associated with these
factors of the model for maximum revenue are computed and verified . The model
response is interpreted in light of the business scenario of data centers.


title: Recent progresses in the theory of nonlinear nonlocal problems

abstract:
  We overview some recent existence and regularity results in the theory of
nonlocal nonlinear problems driven by the fractional $p$-Laplacian.


title:
A Normalizing Computation Rule for Propositional Extensionality in
  Higher-Order Minimal Logic

abstract:
  The univalence axiom expresses the principle of extensionality for dependent
type theory. However, if we simply add the univalence axiom to type theory,
then we lose the property of canonicity - that every closed term computes to a
canonical form. A computation becomes `stuck' when it reaches the point that it
needs to evaluate a proof term that is an application of the univalence axiom.
So we wish to find a way to compute with the univalence axiom. While this
problem has been solved with the formulation of cubical type theory, where the
computations are expressed using a nominal extension of lambda-calculus, it may
be interesting to explore alternative solutions, which do not require such an
extension.
  As a first step, we present here a system of propositional higher-order
minimal logic (PHOML). There are three kinds of typing judgement in PHOML.
There are terms which inhabit types, which are the simple types over $\Omega$.
There are proofs which inhabit propositions, which are the terms of type
$\Omega$. The canonical propositions are those constructed from $\bot$ by
implication $\supset$. Thirdly, there are paths which inhabit equations $M =_A
N$, where $M$ and $N$ are terms of type $A$. There are two ways to prove an
equality: reflexivity, and propositional extensionality - logically equivalent
propositions are equal. This system allows for some definitional equalities
that are not present in cubical type theory, namely that transport along the
trivial path is identity.
  We present a call-by-name reduction relation for this system, and prove that
the system satisfies canonicity: every closed typable term head-reduces to a
canonical form. This work has been formalised in Agda.


title:
Loss of derivatives for hyperbolic boundary problems with constant
  coefficients

abstract:
  Symmetric hyperbolic systems and constantly hyperbolic systems with constant
coefficients and a boundary condition which satisfies a weakened form of the
Kreiss-Sakamoto condition are considered. A well-posedness result is
established which generalizes a theorem by Chazarain and Piriou for scalar
strictly hyperbolic equations and non-characteristic boundaries from 1972. The
proof is based on an explicit solution of the boundary problem by means of the
Fourier-Laplace transform. As long as the operator is symmetric, the boundary
is allowed to be characteristic.


title: Molecular and ionized gas kinematics in the GC Radio Arc

abstract:
  We present NH3 and H64a+H63a VLA observations of the Radio Arc region,
including the M0.20-0.033 and G0.10-0.08 molecular clouds. These observations
suggest the two velocity components of M0.20-0.033 are physically connected in
the south. Additional ATCA observations suggest this connection is due to an
expanding shell in the molecular gas, with the centroid located near the
Quintuplet cluster. The G0.10-0.08 molecular cloud has little radio continuum,
strong molecular emission, and abundant CH3OH masers, similar to a nearby
molecular cloud with no star formation: M0.25+0.01. These features detected in
G0.10-0.08 suggest dense molecular gas with no signs of current star formation.


title:
Microscopic Pedestrian Flow Characteristics: Development of an Image
  Processing Data Collection and Simulation Model

abstract:
  Microscopic pedestrian studies consider detailed interaction of pedestrians
to control their movement in pedestrian traffic flow. The tools to collect the
microscopic data and to analyze microscopic pedestrian flow are still very much
in its infancy. The microscopic pedestrian flow characteristics need to be
understood. Manual, semi manual and automatic image processing data collection
systems were developed. It was found that the microscopic speed resemble a
normal distribution with a mean of 1.38 m/second and standard deviation of 0.37
m/second. The acceleration distribution also bear a resemblance to the normal
distribution with an average of 0.68 m/ square second. A physical based
microscopic pedestrian simulation model was also developed. Both Microscopic
Video Data Collection and Microscopic Pedestrian Simulation Model generate a
database called NTXY database. The formulations of the flow performance or
microscopic pedestrian characteristics are explained. Sensitivity of the
simulation and relationship between the flow performances are described.
Validation of the simulation using real world data is then explained through
the comparison between average instantaneous speed distributions of the real
world data with the result of the simulations. The simulation model is then
applied for some experiments on a hypothetical situation to gain more
understanding of pedestrian behavior in one way and two way situations, to know
the behavior of the system if the number of elderly pedestrian increases and to
evaluate a policy of lane-like segregation toward pedestrian crossing and
inspects the performance of the crossing. It was revealed that the microscopic
pedestrian studies have been successfully applied to give more understanding to
the behavior of microscopic pedestrians flow, predict the theoretical and
practical situation and evaluate some design policies before its
implementation.


title: Modeling Language Change in Historical Corpora: The Case of Portuguese

abstract:
  This paper presents a number of experiments to model changes in a historical
Portuguese corpus composed of literary texts for the purpose of temporal text
classification. Algorithms were trained to classify texts with respect to their
publication date taking into account lexical variation represented as word
n-grams, and morphosyntactic variation represented by part-of-speech (POS)
distribution. We report results of 99.8% accuracy using word unigram features
with a Support Vector Machines classifier to predict the publication date of
documents in time intervals of both one century and half a century. A feature
analysis is performed to investigate the most informative features for this
task and how they are linked to language change.


title: Discriminating Similar Languages: Evaluations and Explorations

abstract:
  We present an analysis of the performance of machine learning classifiers on
discriminating between similar languages and language varieties. We carried out
a number of experiments using the results of the two editions of the
Discriminating between Similar Languages (DSL) shared task. We investigate the
progress made between the two tasks, estimate an upper bound on possible
performance using ensemble and oracle combination, and provide learning curves
to help us understand which languages are more challenging. A number of
difficult sentences are identified and investigated further with human
annotation.


title:
Gaussian and bootstrap approximations for high-dimensional U-statistics
  and their applications

abstract:
  This paper studies the Gaussian and bootstrap approximations for the
probabilities of a non-degenerate U-statistic belonging to the hyperrectangles
in $\mathbb{R}^d$ when the dimension $d$ is large. A two-step Gaussian
approximation procedure that does not impose structural assumptions on the data
distribution is proposed. Subject to mild moment conditions on the kernel, we
establish the explicit rate of convergence uniformly in the class of all
hyperrectangles in $\mathbb{R}^d$ that decays polynomially in sample size for a
high-dimensional scaling limit, where the dimension can be much larger than the
sample size. We also provide computable approximation methods for the quantiles
of the maxima of centered U-statistics. Specifically, we provide a unified
perspective for the empirical bootstrap, the randomly reweighted bootstrap, and
the Gaussian multiplier bootstrap with the jackknife estimator of covariance
matrix as randomly reweighted quadratic forms and we establish their validity.
We show that all three methods are inferentially first-order equivalent for
high-dimensional U-statistics in the sense that they achieve the same uniform
rate of convergence over all $d$-dimensional hyperrectangles. In particular,
they are asymptotically valid when the dimension $d$ can be as large as
$O(e^{n^c})$ for some constant $c \in (0,1/7)$.
  (Full abstract can be found in the paper.)


title:
On the collapsibility of measures of effect in the counterfactual causal
  framework

abstract:
  A measure of association is said to be collapsible over a set of baseline
covariates if the marginal value of the measure of association is equal to a
weighted average of the stratum-specific measures of association. In this
paper, we consider two subtly different definitions of collapsibility, and show
that by considering causal measures of effect based on counterfactual variables
it is possible to separate out the component of non-collapsibility which is due
to the mathematical properties of the effect measure. We provide weights such
that the causal risk difference and the causal risk ratio are collapsible over
arbitrary baseline covariates, and demonstrate that such general weights do not
exist for the odds ratio.


title:
Interaction Between a Domain Wall and Spin Supercurrent in Easy-cone
  Magnets

abstract:
  A domain wall and spin supercurrent can coexist in magnets with easy-cone
anisotropy owing to simultaneous spontaneous breaking of Z$_2$ and U(1)
symmetries. Their interaction is theoretically investigated in quasi
one-dimensional ferromagnets within the Landau-Lifshitz-Gilbert phenomenology.
Specifically, we show that spin supercurrent can exert the torque on a domain
wall and thereby drive it. We also show, as a reciprocal phenomenon, a
field-induced motion of a domain wall can generate spin supercurrent.


title:
Ambiguous Chance-Constrained Binary Programs under Mean-Covariance
  Information

abstract:
  We consider chance-constrained binary programs, where each row of the
inequalities that involve uncertainty needs to be satisfied probabilistically.
Only the information of the mean and covariance matrix is available, and we
solve distributionally robust chance-constrained binary programs (DCBP). Using
two different ambiguity sets, we equivalently reformulate the DCBPs as 0-1
second-order cone (SOC) programs. We further exploit the submodularity of 0-1
SOC constraints under special and general covariance matrices, and utilize the
submodularity as well as lifting to derive extended polymatroid inequalities to
strengthen the 0-1 SOC formulations. We incorporate the valid inequalities in a
branch-and-cut algorithm for efficiently solving DCBPs. We demonstrate the
computational efficacy and solution performance using diverse instances of a
chance-constrained bin packing problem.


title: Nonequilibrium diagrammatic technique for Hubbard Green functions

abstract:
  We introduce diagrammatic technique for Hubbard nonequilibrium Green
functions (NEGF). The formulation is an extension of equilibrium considerations
for strongly correlated lattice models to description of current carrying
molecular junctions. Within the technique intra-system interactions are taken
into account exactly, while molecular coupling to contacts is used as a small
parameter in perturbative expansion. We demonstrate the viability of the
approach with numerical simulations for a generic junction model of quantum dot
coupled to two electron reservoirs.


title: The homotopy theory of type theories

abstract:
  We construct a left semi-model structure on the category of intensional type
theories (precisely, on $\mathrm{CxlCat_{Id,1,\Sigma(,\Pi_{ext})}}$). This
presents an $\infty$-category of such type theories; we show moreover that
there is an $\infty$-functor $\mathrm{Cl}_\infty$ from there to the
$\infty$-category of suitably structured quasi-categories.
  This allows a precise formulation of the conjectures that intensional type
theory gives internal languages for higher categories, and provides a framework
and toolbox for further progress on these conjectures.


title: Non-collinear Order and Spin-Orbit Coupling in Sr$_3$ZnIrO$_6$

abstract:
  Sr$_{3}$ZnIrO$_{6}$ is an effective spin one-half Mott insulating iridate
belonging to a family of magnets which includes a number of quasi-one
dimensional systems as well as materials exhibiting three dimensional order.
Here we present the results of an extensive investigation into the magnetism
including heat capacity, a.c. susceptibility, muon spin rotation ($\mu$SR),
neutron diffraction and inelastic neutron scattering on the same sample. It is
established that the material exhibits a transition at about $17$ K into a
three-dimensional antiferromagnetic structure with propagation vector
$\boldsymbol{k}=(0,\frac{1}{2},1)$ in the hexagonal setting of R$\bar{3}$c and
non-collinear moments of $0.87$$\mu_B$ on Ir$^{4+}$ ions. Further we have
observed a well defined powder averaged spin wave spectrum with zone boundary
energy of $\sim 5$ meV at $5$ K. We stress that a theoretical analysis shows
that the observed non-collinear magnetic structure arises from anisotropic
inter- and intra- chain exchange which has its origin in significant spin-orbit
coupling. The model can satisfactorily explain the observed spin wave
excitations.


title:
Leveraging Contact Network Information in Clustered Observational
  Studies of Contagion Processes

abstract:
  In an observational study, obtaining unbiased estimates of an exposure effect
requires adjusting for all potential confounders. When this condition is met,
leveraging additional covariates related to the outcome may produce less
variable estimates of the effect of exposure. For contagion processes operating
on a contact network, transmission can only occur through ties that connect
exposed and unexposed individuals; the outcome of such a process is known to
depend intimately on the structure of the network. In this paper, we
investigate the use of contact network features as both confounders and
efficiency covariates in exposure effect estimation. Using doubly-robust
augmented generalized estimating equations (GEE), we estimate how gains in
efficiency depend on the network structure and spread of the contagious agent
or behavior. We apply this approach to estimate the effects of two distinct
exposures, the proportion of leaders in a village and the proportion of
households participating in a self-help program, for the spread of a
microfinance program in a collection of villages in Karnataka, India. We
compare these results to simulated observational trials using a stochastic
compartmental contagion model on a collection of model-based contact networks
and compare the bias and variance of the estimated exposure effects using an
assortment of network covariate adjustment strategies.


title: A Primer on Coordinate Descent Algorithms

abstract:
  This monograph presents a class of algorithms called coordinate descent
algorithms for mathematicians, statisticians, and engineers outside the field
of optimization. This particular class of algorithms has recently gained
popularity due to their effectiveness in solving large-scale optimization
problems in machine learning, compressed sensing, image processing, and
computational statistics. Coordinate descent algorithms solve optimization
problems by successively minimizing along each coordinate or coordinate
hyperplane, which is ideal for parallelized and distributed computing. Avoiding
detailed technicalities and proofs, this monograph gives relevant theory and
examples for practitioners to effectively apply coordinate descent to modern
problems in data science and engineering.


title:
Determining quantum correlations in bipartite systems - from qubit to
  qutrit and beyond

abstract:
  We advocate the step change in properties of discrete $d$-level quantum
systems, between $d=2$ and $d\geq 3$. Qubit systems, or multipartite systems
containing qubit subsystem, are exceptional in their relative simplicity. One
faces a step in complexity in valuating measures of quantum correlations for
qutrits and then other higher dimensional qudits. There is a growing number of
arguments leading to such conclusion: recently found no-go theorem for
generalization of the Peres-Horodecki's PPT criterion \cite{sko}, change in
geometry of state spaces of qubit and higher degree qudits (the so called
'generalized Bloch ball' is not a ball anymore), restricted possibilities for
diagonalization of correlation matrices for bipartite systems, more difficult
way for handling the set of relevant families of orthogonal projectors.


title:
A Butterfly-Based Direct Integral Equation Solver Using Hierarchical LU
  Factorization for Analyzing Scattering from Electrically Large Conducting
  Objects

abstract:
  A butterfly-based direct combined-field integral equation (CFIE) solver for
analyzing scattering from electrically large, perfect electrically conducting
objects is presented. The proposed solver leverages the butterfly scheme to
compress blocks of the hierarchical LU-factorized discretized CFIE operator and
uses randomized butterfly reconstruction schemes to expedite the factorization.
The memory requirements and computational cost of the direct butterfly-CFIE
solver scale as $O(N\mathrm{log}^2N)$ and $O(N^{1.5}\mathrm{log}N)$,
respectively. These scaling estimates permit significant memory and CPU savings
when compared to those realized by low-rank (LR) decomposition-based solvers.
The efficacy and accuracy of the proposed solver are demonstrated through its
application to the analysis of scattering from canonical and realistic objects
involving up to 14 million unknowns.


title: Codes for distributed storage from 3-regular graphs

abstract:
  This paper considers distributed storage systems (DSSs) from a graph
theoretic perspective. A DSS is constructed by means of the path decomposition
of a 3- regular graph into P4 paths. The paths represent the disks of the DSS
and the edges of the graph act as the blocks of storage. We deduce the
properties of the DSS from a related graph and show their optimality.


title:
Optimal Energy-Delay Tradeoff for Opportunistic Spectrum Access in
  Cognitive Radio Networks

abstract:
  Cognitive radio (CR) has been considered as a promising technology to enhance
spectrum efficiency via opportunistic transmission at link level. Basic CR
features allow SUs to transmit only when the licensed primary channel is not
occupied by PUs. However, waiting for idle time slot may include large packet
delay and high energy consumption. We further consider that the SU may decide,
at any moment, to use another dedicated way of communication (3G) in order to
transmit its packets. Thus, we consider an Opportunistic Spectrum Access (OSA)
mechanism that takes into account packet delay and energy consumption. We
formulate the OSA problem as a Partially Observable Markov Decision Process
(POMDP) by explicitly considering the energy consumption as well as packets'
delay, which are often ignored in existing OSA solutions. Specifically, we
consider a POMDP with an average reward criterion. We derive structural
properties of the value function and we show the existence of optimal
strategies in the class of the threshold strategies. For implementation
purposes, we propose online learning mechanisms that estimate the PU activity
and determine the appropriate threshold strategy on the fly. In particular,
numerical illustrations validate our theoretical findings.


title: Leaky Modes of Dielectric Cavities

abstract:
  In the absence of external excitation, light trapped within a dielectric
medium generally decays by leaking out (and also by getting absorbed within the
medium). We analyze the leaky modes of a parallel-plate slab, a solid glass
sphere, and a solid glass cylinder, by examining those solutions of Maxwell's
equations (for dispersive as well as non-dispersive media) which admit of a
complex-valued oscillation frequency. Under certain circumstances, these leaky
modes constitute a complete set into which an arbitrary distribution of the
electromagnetic field residing inside a dielectric body can be expanded. We
provide completeness proofs, and also present results of numerical calculations
that illustrate the relationship between the leaky modes and the resonances of
dielectric cavities formed by a simple parallel-plate slab, a glass sphere, and
a glass cylinder.


title: On Topologies on the Group $(\Z_p)^{\N}$

abstract:
  It is proved that, on any Abelian group of infinite cardinality ${\bf m}$,
there exist precisely $2^{2^{\bf m}}$ nonequivalent bounded Hausdorff group
topologies. Under the continuum hypothesis, the number of nonequivalent compact
and locally compact Hausdorff group topologies on the group $(\Z_p)^{\N}$ is
determined.


title: Restrictions from Lorentz invariance violation on cosmic ray propagation

abstract:
  Lorentz Invariance Violation introduced as a generic modification to particle
dispersion relations is used to study high energy cosmic ray attenuation
processes. It is shown to reproduce the same physical effects for vacuum
Cherenkov radiation, as in some particular models with spontaneous breaking of
Lorentz symmetry. This approximation is also implemented for the study of
photon decay in vacuum, where stringent limits to the violation scale are
derived from the direct observation of very high energy cosmic ray photon
events on gamma telescopes. Photo production processes by cosmic ray primaries
on photon background are also addressed, to show that Lorentz violation may
turn off this attenuation process at energies above a well defined secondary
threshold.


title:
Spatial Temporal Exponential-Family Point Process Models for the
  Evolution of Social Systems

abstract:
  We develop a class of exponential-family point processes based on a latent
social space to model the coevolution of social structure and behavior over
time. Temporal dynamics are modeled as a discrete Markov process specified
through individual transition distributions for each actor in the system at a
given time. We prove that these distributions have an analytic closed form
under certain conditions and use the result to develop likelihood-based
inference. We provide a computational framework to enable both simulation and
inference in practice. Finally, we demonstrate the value of these models by
analyzing alcohol and drug use over time in the context of adolescent
friendship networks.


title: Exploiting Universal Redundancy

abstract:
  Fault tolerance is essential for building reliable services; however, it
comes at the price of redundancy, mainly the "replication factor" and
"diversity". With the increasing reliance on Internet-based services, more
machines (mainly servers) are needed to scale out, multiplied with the extra
expense of replication. This paper revisits the very fundamentals of fault
tolerance and presents "artificial redundancy": a formal generalization of
"exact copy" redundancy in which new sources of redundancy are exploited to
build fault tolerant systems. On this concept, we show how to build "artificial
replication" and design "artificial fault tolerance" (AFT). We discuss the
properties of these new techniques showing that AFT extends current fault
tolerant approaches to use other forms of redundancy aiming at reduced cost and
high diversity.


title: Upper semicontinuity of the lamination hull

abstract:
  Let $K \subseteq \mathbb{R}^{2 \times 2}$ be a compact set, let $K^{rc}$ be
its rank-one convex hull, and let $L(K)$ be its lamination convex hull. It is
shown that the mapping $K \to \overline{L(K)}$ is not upper semicontinuous on
the diagonal matrices in $\mathbb{R}^{2 \times 2}$, which was a problem left by
Kol\'a\v{r}. This is followed by an example of a 5-point set of $2 \times 2$
symmetric matrices with non-compact lamination hull. Finally, an example of
another 5-point set $K$ is given, which has $L(K)$ connected, compact and
strictly smaller than $K^{rc}$.


title: Ice Formation on Kaolinite: Insights from Molecular Dynamics Simulations

abstract:
  The formation of ice affects many aspects of our everyday life as well as
technologies such as cryotherapy and cryopreservation. Foreign substances
almost always aid water freezing through heterogeneous ice nucleation, but the
molecular details of this process remain largely unknown. In fact, insight into
the microscopic mechanism of ice formation on different substrates is difficult
to obtain even via state-of-the-art experimental techniques. At the same time,
atomistic simulations of heterogeneous ice nucleation frequently face
extraordinary challenges due to the complexity of the water-substrate
interaction and the long timescales that characterize nucleation events. Here,
we have investigated several aspects of molecular dynamics simulations of
heterogeneous ice nucleation considering as a prototypical ice nucleating
material the clay mineral kaolinite, which is of relevance in atmospheric
science. We show via seeded molecular dynamics simulations that ice nucleation
on the hydroxylated (001) face of kaolinite proceeds exclusively via the
formation of the hexagonal ice polytype. The critical nucleus size is two times
smaller than that obtained for homogeneous nucleation at the same supercooling.
Previous findings suggested that the flexibility of the kaolinite surface can
alter the time scale for ice nucleation within molecular dynamics simulations.
However, we here demonstrate that equally flexible (or non flexible) kaolinite
surfaces can lead to very different outcomes in terms of ice formation,
according to whether or not the surface relaxation of the clay is taken into
account. We show that very small structural changes upon relaxation
dramatically alter the ability of kaolinite to provide a template for the
formation of a hexagonal overlayer of water molecules at the water-kaolinite
interface, and that this relaxation therefore determines the nucleation ability
of this mineral.


title:
Directional Phonon Suppression Function as a Tool for the Identification
  of Ultralow Thermal Conductivity Materials

abstract:
  Boundary-engineering in nanostructures has the potential to dramatically
impact the development of materials for high-efficiency conversion of thermal
energy directly into electricity. In particular, nanostructuring of
semiconductors can lead to strong suppression of heat transport with little
degradation of electrical conductivity. Although this combination of material
properties is promising for thermoelectric materials, it remains largely
unexplored. In this work, we introduce a novel concept, the directional phonon
suppression function, to unravel boundary-dominated heat transport in
unprecedented detail. Using a combination of density functional theory and the
Boltzmann transport equation, we compute this quantity for nanoporous silicon
materials. We first compute the thermal conductivity for the case with aligned
circular pores, confirming a significant thermal transport degradation with
respect to the bulk. Then, by analyzing the information on the directionality
of phonon suppression in this system, we identify a new structure of
rectangular pores with the same porosity that enables a four-fold decrease in
thermal transport with respect to the circular pores. Our results illustrate
the utility of the directional phonon suppression function, enabling new
avenues for systematic thermal conductivity minimization and potentially
accelerating the engineering of next-generation thermoelectric devices.


title: Superconducting optoelectronic circuits for neuromorphic computing

abstract:
  Neural networks have proven effective for solving many difficult
computational problems. Implementing complex neural networks in software is
very computationally expensive. To explore the limits of information
processing, it will be necessary to implement new hardware platforms with large
numbers of neurons, each with a large number of connections to other neurons.
Here we propose a hybrid semiconductor-superconductor hardware platform for the
implementation of neural networks and large-scale neuromorphic computing. The
platform combines semiconducting few-photon light-emitting diodes with
superconducting-nanowire single-photon detectors to behave as spiking neurons.
These processing units are connected via a network of optical waveguides, and
variable weights of connection can be implemented using several approaches. The
use of light as a signaling mechanism overcomes fanout and parasitic
constraints on electrical signals while simultaneously introducing physical
degrees of freedom which can be employed for computation. The use of
supercurrents achieves the low power density necessary to scale to systems with
enormous entropy. The proposed processing units can operate at speeds of at
least $20$ MHz with fully asynchronous activity, light-speed-limited latency,
and power densities on the order of 1 mW/cm$^2$ for neurons with 700
connections operating at full speed at 2 K. The processing units achieve an
energy efficiency of $\approx 20$ aJ per synapse event. By leveraging
multilayer photonics with deposited waveguides and superconductors with feature
sizes $>$ 100 nm, this approach could scale to systems with massive
interconnectivity and complexity for advanced computing as well as explorations
of information processing capacity in systems with an enormous number of
information-bearing microstates.


title: Outlier Detection from Network Data with Subnetwork Interpretation

abstract:
  Detecting a small number of outliers from a set of data observations is
always challenging. This problem is more difficult in the setting of multiple
network samples, where computing the anomalous degree of a network sample is
generally not sufficient. In fact, explaining why the network is exceptional,
expressed in the form of subnetwork, is also equally important. In this paper,
we develop a novel algorithm to address these two key problems. We treat each
network sample as a potential outlier and identify subnetworks that mostly
discriminate it from nearby regular samples. The algorithm is developed in the
framework of network regression combined with the constraints on both network
topology and L1-norm shrinkage to perform subnetwork discovery. Our method thus
goes beyond subspace/subgraph discovery and we show that it converges to a
global optimum. Evaluation on various real-world network datasets demonstrates
that our algorithm not only outperforms baselines in both network and high
dimensional setting, but also discovers highly relevant and interpretable local
subnetworks, further enhancing our understanding of anomalous networks.


title: Minimal free resolution of a graded ideal with linear quotients

abstract:
  Let $I$ be a graded ideal of $K[x_1,\ldots,x_n]$ generated by homogeneous
polynomials of a same degree $d$, and assume that $I$ has linear quotients. In
this note, we use Horseshoe Lemma to give a relatively direct inductive
construction of a minimal free resolution of $I$, which is called a $d$-linear
resolution.


title: Pair entanglement in dimerized spin-s chains

abstract:
  We examine the pair entanglement in the ground state of finite dimerized
spin-$s$ chains interacting through anisotropic $XY$ couplings immersed in a
transverse magnetic field, by means of a self-consistent pair mean field
approximation. The approach, which makes no a priori assumptions on the pair
states, predicts, for sufficiently low coupling between pairs, $2s$ distinct
dimerized phases for increasing fields below the pair factorizing field,
separated by spin parity breaking phases. The dimerized phases lead to
approximate magnetization and pair entanglement plateaus, while the parity
breaking phases are characterized by weak pair entanglement but non-negligible
entanglement of the pair with the rest of the system. These predictions are
confirmed by the exact results obtained in finite $s=1$ and $s=3/2$ chains. It
is also shown that for increasing values of the spin $s$, the entanglement of
an isolated pair, as measured by the negativity, rapidly saturates in the
anisotropic $XY$ case but increases as $s^{1/2}$ in the $XX$ case, reflecting a
distinct single spin entanglement spectrum.


title: BER Performance of Polar Coded OFDM in Multipath Fading

abstract:
  Orthogonal Frequency Division Multiplexing (OFDM) has gained a lot of
popularity over the years. Due to its popularity, OFDM has been adopted as a
standard in cellular technology and Wireless Local Area Network (WLAN)
communication systems. To improve the bit error rate (BER) performance, forward
error correction (FEC) codes are often utilized to protect signals against
unknown interference and channel degradations. In this paper, we apply
soft-decision FEC, more specifically polar codes and a convolutional code, to
an OFDM system in a quasi-static multipath fading channel, and compare BER
performance in various channels. We investigate the effect of interleaving bits
within a polar codeword. Finally, the simulation results for each case are
presented in the paper.


title:
Review of Buffer-Aided Distributed Space-Time Coding Schemes and
  Algorithms for Cooperative Wireless Systems

abstract:
  In this work, we propose buffer-aided distributed space-time coding (DSTC)
schemes and relay selection algorithms for cooperative direct-sequence
code-division multiple access (DS-CDMA) systems. We first devise a relay pair
selection algorithm that can form relay pairs and then select the optimum set
of relays among both the source-relay phase and the relay-destination phase
according to the signal-to-interference-plus-noise ratio (SINR) criterion.
Multiple relays equipped with dynamic buffers are then introduced in the
network, which allows the relays to store data received from the sources and
wait until the most appropriate time for transmission. { A greedy relay pair
selection algorithm is then developed to reduce the high cost of the exhaustive
search required when a large number of relays are involved.} The proposed
techniques effectively improve the quality of the transmission with an
acceptable delay as the buffer size is adjustable. An analysis of the
computational complexity of the proposed algorithms, the delay and a study of
the greedy algorithm are then carried out. Simulation results show that the
proposed dynamic buffer-aided DSTC schemes and algorithms outperform prior art.


title:
Cross-correlation search for continuous gravitational waves from a
  compact object in SNR 1987A in LIGO Science Run 5

abstract:
  We present the results of a cross-correlation search for gravitational waves
from SNR 1987A using the second year of LIGO Science Run 5 data. The frequency
band 75--450\,Hz is searched. No evidence of gravitational waves is found. A
90\% confidence upper limit of $h_0 \leq 3.8\times10^{-25}$ is placed on the
gravitational wave strain at the most sensitive frequency near 150\,Hz. This
corresponds to an ellipticity of $\epsilon \leq 8.2\times10^{-4}$ and improves
on previously published strain upper limits by a factor $\approx4$. We perform
a comprehensive suite of validations of the search algorithm and identify
several computational savings which marginally sacrifice sensitivity in order
to streamline the parameter space being searched. We estimate detection
thresholds and sensitivities through Monte-Carlo simulations.


title:
Global well-posedness for passively transported nonlinear moisture
  dynamics with phase changes

abstract:
  We study a moisture model for warm clouds that has been used by Klein and
Majda as a basis for multiscale asymptotic expansions for deep convective
phenomena. These moisture balance equations correspond to a bulk microphysics
closure in the spirit of Kessler and of Grabowski and Smolarkiewicz, in which
water is present in the gaseous state as water vapor and in the liquid phase as
cloud water and rain water. It thereby contains closures for the phase changes
condensation and evaporation, as well as the processes of autoconversion of
cloud water into rainwater and the collection of cloud water by the falling
rain droplets. Phase changes are associated with enormous amounts of latent
heat and therefore provide a strong coupling to the thermodynamic equation.
  In this work we assume the velocity field to be given and prove rigorously
the global existence and uniqueness of uniformly bounded solutions of the
moisture model with viscosity, diffusion and heat conduction. To guarantee
local well-posedness we first need to establish local existence results for
linear parabolic equations, subject to the Robin boundary conditions on the
cylindric type of domains under consideration. We then derive a priori
estimates, for proving the maximum principle, using the Stampacchia method, as
well as the iterative method by Alikakos to obtain uniform boundedness. The
evaporation term is of power law type, with an exponent in general less or
equal to one and therefore making the proof of uniqueness more challenging.
However, these difficulties can be circumvented by introducing new unknowns,
which satisfy the required cancellation and monotonicity properties in the
source terms.

categories: math.AP physics.ao-ph physics.flu-dyn physics.geo-ph


title: Field Stabilization of Alvarez-Type Cavities

abstract:
  Alvarez-type cavities are commonly used to reliably accelerate high quality
hadron beams. Optimization of their longitudinal field homogeneity is usually
accomplished by post-couplers, i.e. additional rods being integrated into the
cavity. This paper instead proposes to use the stems that keep the drift tubes
for that purpose. As their individual azimuthal orientations do not change the
cavity's undisturbed operational mode, they comprise a set of free parameters
that can be used to modify higher mode field patterns. The latter have
significant impact on the robustness of the operational mode w.r.t. eventual
perturbations. Several optimized stem configurations are presented and
benchmarked against each other. The path to obtain these configurations is
paved analytically and worked out in detail through simulations. It is shown
that the method provides for flat field distributions and very low field tilt
sensitivities without insertion of post-couplers.


title:
Influence of the Substrate Material on the Optical Properties of
  Tungsten Diselenide Monolayers

abstract:
  Monolayers of transition-metal dichalcogenides such as WSe2 have become
increasingly attractive due to their potential in electrical and optical
applications. Because the properties of these 2D systems are known to be
affected by their surroundings, we report how the choice of the substrate
material affects the optical properties of monolayer WSe2. To accomplish this
study, pump-density-dependent micro-photoluminescence measurements are
performed with time-integrating and time-resolving acquisition techniques.
Spectral information and power-dependent mode intensities are compared at 290K
and 10K for exfoliated WSe2 on SiO2/Si, sapphire (Al2O3), hBN/Si3N4/Si, and
MgF2, indicating substrate-dependent appearance and strength of exciton, trion,
and biexciton modes. Additionally, one CVD-grown WSe2 monolayer on sapphire is
included in this study for direct comparison with its exfoliated counterpart.
Time-resolved micro-photoluminescence shows how radiative decay times strongly
differ for different substrate materials. Our data indicates exciton-exciton
annihilation as a shortening mechanism at room temperature, and subtle trends
in the decay rates in correlation to the dielectric environment at cryogenic
temperatures. On the measureable time scales, trends are also related to the
extent of the respective 2D-excitonic modes' appearance. This result highlights
the importance of further detailed characterization of exciton features in 2D
materials, particularly with respect to the choice of substrate.


title: Minimal Inputs/Outputs for a Networked System

abstract:
  This paper investigates the minimal number of inputs/outputs required to
guarantees the controllability/observability of a system, under the condition
that its state transition matrix (STM) is prescribed. It has been proved that
this minimal number is equal to the maximum geometric multiplicity of the
system STM. The obtained conclusions are in sharp contrast to those established
for the problems of finding the sparest input/output matrix under the
restriction of system controllability/observabilty, which have been proved to
be NP-hard, and even impossible to be approximated within a multiplicative
factor. Moreover, a complete parametrization is also provided for the
input/output matrix of a system with this minimal input/output number.


title: Faster Kernels for Graphs with Continuous Attributes via Hashing

abstract:
  While state-of-the-art kernels for graphs with discrete labels scale well to
graphs with thousands of nodes, the few existing kernels for graphs with
continuous attributes, unfortunately, do not scale well. To overcome this
limitation, we present hash graph kernels, a general framework to derive
kernels for graphs with continuous attributes from discrete ones. The idea is
to iteratively turn continuous attributes into discrete labels using randomized
hash functions. We illustrate hash graph kernels for the Weisfeiler-Lehman
subtree kernel and for the shortest-path kernel. The resulting novel graph
kernels are shown to be, both, able to handle graphs with continuous attributes
and scalable to large graphs and data sets. This is supported by our
theoretical analysis and demonstrated by an extensive experimental evaluation.


title:
Realistic inversion of diffraction data for an amorphous solid: the case
  of amorphous silicon

abstract:
  We apply a new method "force enhanced atomic refinement" (FEAR) to create a
computer model of amorphous silicon (a-Si), based upon the highly precise X-ray
diffraction experiments of Laaziri et al. The logic underlying our calculation
is to estimate the structure of a real sample a-Si using experimental data and
chemical information included in a non-biased way, starting from random
coordinates. The model is in close agreement with experiment and also sits at a
suitable minimum energy according to density functional calculations. In
agreement with experiments, we find a small concentration of coordination
defects that we discuss, including their electronic consequences. The gap
states in the FEAR model are delocalized compared to a continuous random
network model. The method is more efficient and accurate, in the sense of
fitting the diffraction data than conventional melt quench methods. We compute
the vibrational density of states and the specific heat, and find that both
compare favorably to experiments.


title: Examples of non-FSZ p-groups for primes greater than three

abstract:
  For any prime $p>3$ and $j\in\mathbb{N}$ we construct examples of
non-$FSZ_{p^j}$ groups of order $p^{p^j+2j-1}$. In the special case of $j=1$
this yields groups of order $p^{p+1}$, which is the minimum possible order for
a non-$FSZ$ $p$-group.


title: On the Stability of Cubic Galileon Accretion

abstract:
  We examine the stability of steady-state galileon accretion for the case of a
Schwarzshild black hole. Considering the galileon action up to the cubic term
in a static and spherically symmetric background we obtain the general solution
for the equation of motion which is divided in two branches. By perturbing this
solution we define an effective metric which determines the propagation of
fluctuations. In this general picture we establish the position of the sonic
horizon together with the matching condition of the two branches on it.
Restricting to the case of a Schwarzschild background, we show, via the
analysis of the energy of the perturbations and its time derivative, that the
accreting field is linearly stable.


title:
Effect heterogeneity and variable selection for standardizing causal
  effects to a target population

abstract:
  The participants in randomized trials and other studies used for causal
inference are often not representative of the populations seen by clinical
decision-makers. To account for differences between populations, researchers
may consider standardizing results to a target population. We discuss several
different types of homogeneity conditions that are relevant for
standardization: Homogeneity of effect measures, homogeneity of counterfactual
outcome state transition parameters, and homogeneity of counterfactual
distributions. Each of these conditions can be used to show that a particular
standardization procedure will result in unbiased estimates of the effect in
the target population, given assumptions about the relevant scientific context.
We compare and contrast the homogeneity conditions, in particular their
implications for selection of covariates for standardization and their
implications for how to compute the standardized causal effect in the target
population. While some of the recently developed counterfactual approaches to
generalizability rely upon homogeneity conditions that avoid many of the
problems associated with traditional approaches, they often require adjustment
for a large (and possibly unfeasible) set of covariates.


title:
The choice of effect measure for binary outcomes: Introducing
  counterfactual outcome state transition parameters

abstract:
  Standard measures of effect, including the risk ratio, the odds ratio, and
the risk difference, are associated with a number of well-described
shortcomings, and no consensus exists about the conditions under which
investigators should choose one effect measure over another. In this paper, we
introduce a new framework for reasoning about choice of effect measure by
linking two separate versions of the risk ratio to a counterfactual causal
model. In our approach, effects are defined in terms of "counterfactual outcome
state transition parameters", that is, the proportion of those individuals who
would not have been a case by the end of follow-up if untreated, who would have
responded to treatment by becoming a case; and the proportion of those
individuals who would have become a case by the end of follow-up if untreated
who would have responded to treatment by not becoming a case. Although
counterfactual outcome state transition parameters are generally not identified
from the data without strong monotonicity assumptions, we show that when they
stay constant between populations, there are important implications for model
specification, meta-analysis, and research generalization.


title:
Radial Velocity Retrieval for Multichannel SAR Moving Targets with
  Time-Space Doppler De-ambiguity

abstract:
  In this paper, with respect to multichannel synthetic aperture radars (SAR),
we first formulate the problems of Doppler ambiguities on the radial velocity
(RV) estimation of a ground moving target in range-compressed domain,
range-Doppler domain and image domain, respectively. It is revealed that in
these problems, a cascaded time-space Doppler ambiguity (CTSDA) may encounter,
i.e., time domain Doppler ambiguity (TDDA) in each channel arises first and
then spatial domain Doppler ambiguity (SDDA) among multi-channels arises
second. Accordingly, the multichannel SAR systems with different parameters are
investigated in three different cases with diverse Doppler ambiguity
properties, and a multi-frequency SAR is then proposed to obtain the RV
estimation by solving the ambiguity problem based on Chinese remainder theorem
(CRT). In the first two cases, the ambiguity problem can be solved by the
existing closed-form robust CRT. In the third case, it is found that the
problem is different from the conventional CRT problems and we call it a double
remaindering problem in this paper. We then propose a sufficient condition
under which the double remaindering problem, i.e., the CTSDA, can also be
solved by the closed-form robust CRT. When the sufficient condition is not
satisfied for a multi-channel SAR, a searching based method is proposed.
Finally, some results of numerical experiments are provided to demonstrate the
effectiveness of the proposed methods.


title:
Quality of Service (QoS) and Security Provisioning in Cooperative Mobile
  Ad Hoc Networks (MANETs)

abstract:
  Cooperative communication can improve communication quality in wireless
communication networks through strategic relay selection. However, wireless
cooperative communication networks are vulnerable to the attacks initiated on
relays. Although applying authentication protocols can secure cooperative
communication when the selected relay is malicious, better system throughput
could be obtained without executing authentication protocol when the selected
relay is free from attacker's attack. In this paper, a game theoretic approach
is proposed to quantitatively analyze the attacking strategies of the attacker
who chooses one relay to attack so as to make rational decision on relay
selection and extent of applying authentication protocols, which reaches the
trade-off between system security requirement and quality of service (QoS) in
wireless cooperative communication networks.


title: Vocabulary Selection Strategies for Neural Machine Translation

abstract:
  Classical translation models constrain the space of possible outputs by
selecting a subset of translation rules based on the input sentence. Recent
work on improving the efficiency of neural translation models adopted a similar
strategy by restricting the output vocabulary to a subset of likely candidates
given the source. In this paper we experiment with context and embedding-based
selection methods and extend previous work by examining speed and accuracy
trade-offs in more detail. We show that decoding time on CPUs can be reduced by
up to 90% and training time by 25% on the WMT15 English-German and WMT16
English-Romanian tasks at the same or only negligible change in accuracy. This
brings the time to decode with a state of the art neural translation system to
just over 140 msec per sentence on a single CPU core for English-German.


title:
Effects of biaxial strain on the improper multiferroicity in h-LuFeO3
  films

abstract:
  Elastic strain is potentially an important approach in tuning the properties
of the improperly multiferroic hexagonal ferrites, the details of which have
however been elusive due to the experimental difficulties. Employing the method
of restrained thermal expansion, we have studied the effect of isothermal
biaxial strain in the basal plane of h-LuFeO3 (001) films. The results indicate
that a compressive biaxial strain significantly enhances the ferrodistortion,
and the effect is larger at higher temperatures. The compressive biaxial strain
and the enhanced ferrodistortion together, cause an increase in the electric
polarization and a reduction in the canting of the weak ferromagnetic moments
in h-LuFeO3, according to our first principle calculations. These findings are
important for understanding the strain effect as well as the coupling between
the lattice and the improper multiferroicity in h-LuFeO3. The experimental
elucidation of the strain effect in h-LuFeO3 films also suggests that the
restrained thermal expansion can be a viable method to unravel the strain
effect in many other epitaxial thin film materials.


title: Acoustic Streaming: An Arbitrary Lagrangian-Eulerian Perspective

abstract:
  We analyze acoustic streaming flows using an ALE perspective. The formulation
stems from an explicit separation of time-scales resulting in two subproblems:
a first-order problem, formulated in terms of the fluid displacement at the
fast scale, and a second-order problem formulated in terms of the Lagrangian
flow velocity at the slow time scale. Following a rigorous time-averaging
procedure, the second-order problem is shown to be intrinsically steady, and
with exact boundary conditions at the oscillating walls. Also, as the
second-order problem is solved directly for the Lagrangian velocity, the
formulation does not need to employ the notion of Stokes drift, or any
associated post-processing, thus facilitating a direct comparison with
experiments. Because the first-order problem is formulated in terms of the
displacement field, our formulation is directly applicable to more complex
fluid-structure interaction problems in microacosutofluidic devices. After the
formulation's exposition, we present numerical results that illustrate the
advantages of the formulation with respect to current approaches.