title:
Thermoelectric transport in disordered metals without quasiparticles:
  the SYK models and holography

abstract:
  We compute the thermodynamic properties of the Sachdev-Ye-Kitaev (SYK) models
of fermions with a conserved fermion number, $\mathcal{Q}$. We extend a
previously proposed Schwarzian effective action to include a phase field, and
this describes the low temperature energy and $\mathcal{Q}$ fluctuations. We
obtain higher-dimensional generalizations of the SYK models which display
disordered metallic states without quasiparticle excitations, and we deduce
their thermoelectric transport coefficients. We also examine the corresponding
properties of Einstein-Maxwell-scalar theories on black brane geometries which
interpolate from either AdS$_4$ or AdS$_5$ to an AdS$_2\times \mathbb{R}^2$ or
AdS$_2\times \mathbb{R}^3$ near-horizon geometry. These provide holographic
descriptions of non-quasiparticle metallic states without momentum
conservation. We find a precise match between low temperature transport and
thermodynamics of the SYK and holographic models. In both models the Seebeck
transport coefficient is exactly equal to the $\mathcal{Q}$-derivative of the
entropy. For the SYK models, quantum chaos, as characterized by the butterfly
velocity and the Lyapunov rate, universally determines the thermal diffusivity,
but not the charge diffusivity.


title: Triggering Soft Bombs at the LHC

abstract:
  Very high multiplicity, spherically-symmetric distributions of soft
particles, with $p_T$ ~ few hundred MeV, may be a signature of strongly-coupled
hidden valleys that exhibit long, efficient showering windows. With traditional
triggers, such "soft bomb" events closely resemble pile-up and are therefore
only recorded with minimum bias triggers at a very low efficiency. We
demonstrate a proof-of-concept for a high-level triggering strategy that
efficiently separates soft bombs from pile-up by searching for a "belt of
fire": A high density band of hits on the innermost layer of the tracker.
Seeding our proposed high-level trigger with existing jet, missing transverse
energy or lepton hardware-level triggers, we show that net trigger efficiencies
of order 10% are possible for bombs of mass several hundred GeV. We also
consider the special case that soft bombs are the result of an exotic decay of
the 125 GeV Higgs. The fiducial rate for "Higgs bombs" triggered in this manner
is marginally higher than the rate achievable by triggering directly on a hard
muon from associated Higgs production.


title:
Cluster algorithms for frustrated two dimensional Ising antiferromagnets
  via dual worm constructions

abstract:
  We report on the development of two dual worm constructions that lead to
cluster algorithms for efficient and ergodic Monte Carlo simulations of
frustrated Ising models with arbitrary two-spin interactions that extend up to
third-neighbours on the triangular lattice. One of these algorithms generalizes
readily to other frustrated systems, such as Ising antiferromagnets on the
Kagome lattice with further neighbour couplings. We characterize the
performance of both these algorithms in a challenging regime with power-law
correlations at finite wavevector.


title:
On the validity of the Born approximation for beyond-Gaussian weak
  lensing observables

abstract:
  Accurate forward modeling of weak lensing (WL) observables from cosmological
parameters is necessary for upcoming galaxy surveys. Because WL probes
structures in the non-linear regime, analytical forward modeling is very
challenging, if not impossible. Numerical simulations of WL features rely on
ray-tracing through the outputs of $N$-body simulations, which requires
knowledge of the gravitational potential and accurate solvers for light ray
trajectories. A less accurate procedure, based on the Born approximation, only
requires knowledge of the density field, and can be implemented more
efficiently and at a lower computational cost. In this work, we use simulations
to show that deviations of the Born-approximated convergence power spectrum,
skewness and kurtosis from their fully ray--traced counterparts are consistent
with the smallest non-trivial $O(\Phi^3)$ post-Born corrections (so-called
geodesic and lens-lens terms). Our results imply a cancellation among the
larger $O(\Phi^4)$ (and higher order) terms, consistent with previous analytic
work. We also find that cosmological parameter bias induced by the Born
approximated power spectrum is negligible even for an LSST-like survey, once
galaxy shape noise is considered. When considering higher order statistics such
as the $\kappa$ skewness and kurtosis, however, we find significant bias of up
to 2.5$\sigma$. Using the LensTools software suite, we show that the Born
approximation saves a factor of 4 in computing time with respect to the full
ray-tracing in reconstructing the convergence.


title: S-duality in $\mathcal{N} = 1$ orientifold SCFTs

abstract:
  We present a general solution to the problem of determining all S-dual
descriptions for a specific (but very rich) class of $\mathcal{N} = 1$ SCFTs.
These SCFTs are indexed by decorated toric diagrams, and can be engineered in
string theory by probing orientifolds of isolated toric singularities with D3
branes. The S-dual phases are described by quiver gauge theories coupled to
specific types of conformal matter which we describe explicitly. We illustrate
our construction with many examples, including S-dualities in previously
unknown SCFTs.


title:
Discrete integrable systems, Darboux transformations, and Yang-Baxter
  maps

abstract:
  These lecture notes are devoted to the integrability of discrete systems and
their relation to the theory of Yang-Baxter (YB) maps. Lax pairs play a
significant role in the integrability of discrete systems. We introduce the
notion of Lax pair by considering the well-celebrated doubly-infinite Toda
lattice. In particular, we present solution of the Cauchy initial value problem
via the method of the inverse scattering transform, provide a review of
scattering theory of Jacobi matrices, and give the Riemann-Hilbert formulation
of the inverse scattering transform. On the other hand, the Lax-Darboux scheme
constitutes an important tool in the theory of integrable systems, as it
relates several concepts of integrability. We explain the role of Darboux and
B\"acklund trasformations in the theory of integrable systems, and we show how
they can be used to construct discrete integrable systems via the Lax-Darboux
scheme. Moreover, we give an introduction to the theory of Yang-Baxter maps and
we show its relation to discrete integrable systems. Finally, we demonstrate
the construction of Yang-Baxter maps via Darboux transformations, using the
nonlinear Schr\"odinger equation as illustrative example.


title: Highly repeatable nanoscale phase coexistence in vanadium dioxide films

abstract:
  The metal-insulator transition (MIT) in vanadium dioxide (VO2) has the
potential to lead to a number of disruptive technologies, including ultra-fast
data storage, optical switches, and transistors which move beyond the
limitations of silicon. For applications, VO2 films are deposited on
crystalline substrates to prevent cracking observed in bulk VO2 crystals across
the thermally driven MIT. Near the MIT, VO2 films exhibit nanoscale coexistence
between metallic and insulating phases, which opens up further potential
applications such as memristors, tunable capacitors, and optically engineered
devices such as perfect absorbers. It is generally believed that the formation
of phase domains must be affected to some extent by random processes which lead
to unreliable performance in nanoscale MIT based devices. Here we show that
nanoscale randomness is suppressed in the thermally driven MIT in sputtered VO2
films; the observed domain patterns of metallic and insulating phases in the
vicinity of the MIT in these films behave in a strikingly reproducible way.
This result opens the door for realizing reliable nanoscale VO2 devices.


title: Stokes paradox in electronic Fermi liquids

abstract:
  The Stokes paradox is the statement that in a viscous two dimensional fluid,
the "linear response" problem of fluid flow around an obstacle is ill-posed. We
present a simple consequence of this paradox in the hydrodynamic regime of a
Fermi liquid of electrons in two-dimensional metals. Using hydrodynamics and
kinetic theory, we estimate the contribution of a single cylindrical obstacle
to the global electrical resistance of a material, within linear response.
Momentum relaxation, present in any realistic electron liquid, resolves the
classical paradox. Nonetheless, this paradox imprints itself in the resistance,
which can be parametrically larger than predicted by Ohmic transport theory. We
find a remarkably rich set of behaviors, depending on whether or not the
quasiparticle dynamics in the Fermi liquid should be treated as diffusive,
hydrodynamic or ballistic on the length scale of the obstacle. We argue that
all three types of behavior are observable in present day experiments.


title: Varieties for modules of finite dimensional Hopf algebras

abstract:
  We survey variety theory for modules of finite dimensional Hopf algebras,
recalling some definitions and basic properties of support and rank varieties
where they are known. We focus specifically on properties known for classes of
examples such as finite group algebras and finite group schemes. We list open
questions about tensor products of modules and projectivity, where varieties
may play a role in finding answers.


title: Efficient Z-Gates for Quantum Computing

abstract:
  For superconducting qubits, microwave pulses drive rotations around the Bloch
sphere. The phase of these drives can be used to generate zero-duration
arbitrary "virtual" Z-gates which, combined with two $X_{\pi/2}$ gates, can
generate any SU(2) gate. Here we show how to best utilize these virtual Z-gates
to both improve algorithms and correct pulse errors. We perform randomized
benchmarking using a Clifford set of Hadamard and Z-gates and show that the
error per Clifford is reduced versus a set consisting of standard
finite-duration X and Y gates. Z-gates can correct unitary rotation errors for
weakly anharmonic qubits as an alternative to pulse shaping techniques such as
DRAG. We investigate leakage and show that a combination of DRAG pulse shaping
to minimize leakage and Z-gates to correct rotation errors (DRAGZ) realizes a
13.3~ns $X_{\pi/2}$ gate characterized by low error ($1.95[3]\times 10^{-4}$)
and low leakage ($3.1[6]\times 10^{-6}$). Ultimately leakage is limited by the
finite temperature of the qubit, but this limit is two orders-of-magnitude
smaller than pulse errors due to decoherence.


title:
Optical Frequency Locked Loop for long-term stabilization of broad-line
  DFB lasers frequency difference

abstract:
  We present an experimental realization of the Optical Frequency Locked Loop
(OFLL) applied to long-term frequency difference stabilization of broad-line
DFB lasers. The presented design, based on an integrated phase-frequency
detector chip, is digitally tunable in real-time, robust against environmental
perturbations and compatible with commercially available laser current control
modules. We present a simple model and a quick method to optimize the loop for
given hardware using only simple measurements in time domain and approximate
laser linewidth. We demonstrate frequency stabilization for offsets
encompassing entire 4-15 GHz capture range. We achieve < 0.5 Hz long-term
stability of the beat note frequency for 1000 s averaging time. Step response
of the system as well as phase characteristics closely adhere to the
theoretical model.


title: Thermodynamics of interacting tachyonic scalar field

abstract:
  In this paper we discuss the laws of thermodynamics for interacting tachyonic
scalar field. The components of the tachyonic scalar field in the universe are
taken to exist in the state of non-equilibrium initially, but due to
interaction they undergo a transition towards the equilibrium state. We show
that the zeroth law of thermodynamics demands interaction among the components
of cosmic field. The second law of thermodynamics is governing dynamics in
transfer of energy among the three components of the proposed field with local
violation of conservation of energy for individual components.


title: Gravitational microlensing in Verlinde's emergent gravity

abstract:
  We propose gravitational microlensing as a way of testing the emergent
gravity theory recently proposed by Eric Verlinde~\cite{Verlinde:2016toy}. We
consider two limiting cases: the dark mass of maximally anisotropic pressures
(Case I) and of isotropic pressures (Case II). Our analysis of perihelion
advancement of a planet shows that only Case I yields a viable theory. In this
case the metric outside a star of mass $M_*$ can be modeled by that of a
point-like global monopole whose mass is $M_*$ and a deficit angle $\Delta =
\sqrt{(2GH_0M_*)/(3c^3)}$, where $H_0$ is the Hubble rate and $G$ the Newton
constant. This deficit angle can be used to test the theory since light
exhibits additional bending around stars given by, $\alpha_D\approx
-\pi\Delta/2$. This angle is independent on the distance from the star and it
affects equally light and massive particles. The effect is too small to be
measurable today, but should be within reach of the next generation of high
resolution telescopes. Finally we note that the advancement of periastron of a
planet orbiting around a star or black hole, which equals $\pi\Delta$ per
period, can be also used to test the theory.


title:
Some Open Problems Concerning Orthogonal Polynomials on Fractals and
  Related Questions

abstract: Some Open Problems Concerning Orthogonal Polynomials.


title: Three lectures on statistical mechanics

abstract:
  These lectures were prepared for the 2014 PCMI graduate summer school and
were designed to be a lightweight introduction to statistical mechanics for
mathematicians. The applications feature some of the themes of the summer
school: sphere packings and tilings.


title: From the Glasma to the QCD Phase Boundary

abstract:
  In this paper, I qualitatively discuss the matter formed in the fragmentation
region of nuclear collisions at the highest energies. I argue that although the
initial temperature and baryon number density can become very large, the ratio
of initial baryon chemical potential to initial temperature is approximately
independent of energy, when measured at a fixed rapidity measured from the end
of the fragmentation region. This quantity is argued to be roughly invariant
under expansion, and therefore the value measured at decoupling should be
approximately the same as the initial value and largely independent of energy.
The values of the initial temperature and initial baryon number are energy
dependent and become large as the center of mass collision energy increases.


title:
The giant acoustic atom -- a single quantum system with a deterministic
  time delay

abstract:
  We investigate the quantum dynamics of a single transmon qubit coupled to
surface acoustic waves (SAWs) via two distant connection points. Since the
acoustic speed is five orders of magnitude slower than the speed of light, the
travelling time between the two connection points needs to be taken into
account. Therefore, we treat the transmon qubit as a giant atom with a
deterministic time delay. We find that the spontaneous emission of the system,
formed by the giant atom and the SAWs between its connection points, initially
decays polynomially in the form of pulses instead of a continuous exponential
decay behaviour, as would be the case for a small atom. We obtain exact
analytical results for the scattering properties of the giant atom up to
two-phonon processes by using a diagrammatic approach. We find that two peaks
appear in the inelastic (incoherent) power spectrum of the giant atom, a
phenomenon which does not exist for a small atom. The time delay also gives
rise to novel features in the reflectance, transmittance, and second-order
correlation functions of the system. Furthermore, we find the short-time
dynamics of the giant atom for arbitrary drive strength by a numerically exact
method for open quantum systems with a finite-time-delay feedback loop.


title: Creating a Real-Time, Reproducible Event Dataset

abstract:
  The generation of political event data has remained much the same since the
mid-1990s, both in terms of data acquisition and the process of coding text
into data. Since the 1990s, however, there have been significant improvements
in open-source natural language processing software and in the availability of
digitized news content. This paper presents a new, next-generation event
dataset, named Phoenix, that builds from these and other advances. This dataset
includes improvements in the underlying news collection process and event
coding software, along with the creation of a general processing pipeline
necessary to produce daily-updated data. This paper provides a face validity
checks by briefly examining the data for the conflict in Syria, and a
comparison between Phoenix and the Integrated Crisis Early Warning System data.


title:
Impact of Dynamic Line Rating on Dispatch Decisions and Integration of
  Variable RES Energy

abstract:
  Dynamic line rating (DLR) models the transmission capacity of overhead lines
as a function of ambient conditions. It takes advantage of the physical thermal
property of overhead line conductors, thus making DLR less conservative
compared to the traditional worst-case oriented nominal line rating (NLR).
Employing DLR brings potential benefits for grid integration of variable
Renewable Energy Sources (RES), such as wind and solar energy. In this paper,
we reproduce weather conditions from renewable feed-ins and local temperature
records, and calculate DLR in accordance with the RES feed-in and load demand
data step. Simulations with high time resolution, using a predictive dispatch
optimization and the Power Node modeling framework, of a six-node benchmark
power system loosely based on the German power system are performed for the
current situation, using actual wind and PV feed-in data. The integration
capability of DLR under high RES production shares is inspected through
simulations with scaled-up RES profiles and reduced dispatchable generation
capacity. The simulation result demonstrates a comparison between DLR and NLR
in terms of reductions in RES generation curtailments and load shedding, while
discussions on the practicality of adopting DLR in the current power system is
given in the end.


title: Symmetry and Action for Flavor-Kinematics Duality

abstract:
  We propose a new representation of the nonlinear sigma model that exhibits a
manifest duality between flavor and kinematics. The fields couple exclusively
through cubic Feynman vertices which also serve as the structure constants of
an underlying kinematic algebra. The action is invariant under a combination of
internal and spacetime symmetries whose conservation equations imply
flavor-kinematics duality, ensuring that all Feynman diagrams satisfy kinematic
Jacobi identities. Substituting flavor for kinematics, we derive a new cubic
action for the special Galileon theory. In this picture, the vanishing soft
behavior of amplitudes is a byproduct of the Weinberg soft theorem.


title:
A New Approach to Numerical Computation of Hausdorff Dimension of
  Iterated Function Systems: Applications to Complex Continued Fractions

abstract:
  In a previous paper, dealing with "Applications in $\mathbb{R}^1$," the
authors developed a new approach to the computation of the Hausdorff dimension
of the invariant set of an iterated function system or IFS and studied some
applications in one dimension. The key idea, which has been known in varying
degrees of generality for many years, is to associate to the IFS a parametrized
family of positive, linear, Perron-Frobenius operators $L_s$. In our context,
$L_s$ is studied in a space of $C^m$ functions and is not compact.
Nevertheless, it is has a strictly positive $C^m$ eigenfunction $v_s$ with
positive eigenvalue $\lambda_s$ equal to the spectral radius of $L_s$. Under
appropriate assumptions on the IFS, the Hausdorff dimension of the invariant
set of the IFS is the value $s=s_*$ for which $\lambda_s =1$. To compute the
Hausdorff dimension of an IFS associated to complex continued fractions, (which
may arise from an infinite iterated function system), we again approximate the
eigenvalue problem by a collocation method, but now using continuous piecewise
bilinear functions. Using the theory of positive linear operators and explicit
a priori bounds on the partial derivatives of the strictly positive
eigenfunction $v_s$, we are able to give rigorous upper and lower bounds for
the Hausdorff dimension $s_*$, and these bounds converge to $s_*$ as the mesh
size approaches zero. We also demonstrate by numerical computations that
improved estimates can be obtained by the use of higher order piecewise tensor
product polynomial approximations, although the present theory does not
guarantee that these are strict upper and lower bounds. An important feature of
our approach is that it also applies to the much more general problem of
computing approximations to the spectral radius of positive transfer operators,
which arise in many other applications.


title:
$C^m$ Eigenfunctions of Perron-Frobenius Operators and a New Approach to
  Numerical Computation of Hausdorff Dimension: Applications in $\mathbb{R}^1$

abstract:
  We develop a new approach to the computation of the Hausdorff dimension of
the invariant set of an iterated function system or IFS. In the one dimensional
case that we consider here, our methods require only $C^3$ regularity of the
maps in the IFS. The key idea, which has been known in varying degrees of
generality for many years, is to associate to the IFS a parametrized family of
positive, linear, Perron-Frobenius operators $L_s$. The operators $L_s$ can
typically be studied in many different Banach spaces. Here, unlike most of the
literature, we study $L_s$ in a Banach space of real-valued, $C^k$ functions,
$k \ge 2$. We note that $L_s$ is not compact, but has essential spectral radius
$\rho_s$ strictly less than the spectral radius $\lambda_s$ and possesses a
strictly positive $C^k$ eigenfunction $v_s$ with eigenvalue $\lambda_s$. Under
appropriate assumptions on the IFS, the Hausdorff dimension of the invariant
set of the IFS is the value $s=s_*$ for which $\lambda_s =1$. This eigenvalue
problem is then approximated by a collocation method using continuous piecewise
linear functions. Using the theory of positive linear operators and explicit a
priori bounds on the derivatives of the strictly positive eigenfunction $v_s$,
we give rigorous upper and lower bounds for the Hausdorff dimension $s_*$, and
these bounds converge to $s_*$ as the mesh size approaches zero.


title:
Repetition rate stabilization of an optical frequency comb based on
  solid-state laser technology with an intra-cavity electro-optic modulator

abstract:
  The repetition rate stabilization of an optical frequency comb based on
diode-pumped solid-state laser technology is demonstrated using an intra-cavity
electro-optic modulator. The large feedback bandwidth of such modulators allows
disciplining the comb repetition rate on a cavity-stabilized continuous-wave
laser with a locking bandwidth up to 700 kHz. This surpasses what can be
achieved with any other type of actuator reported so far. An in-loop integrated
phase noise of 133 mrad has been measured and the PM-to-AM coupling of the
electro-optic modulator has been investigated as well.


title: The Circumgalactic Medium in Massive Halos

abstract:
  This chapter presents a review of the current state of knowledge on the cool
(T ~ 1e4 K) halo gas content around massive galaxies at z ~ 0.2-2. Over the
last decade, significant progress has been made in characterizing the cool
circumgalactic gas in massive halos of Mh ~ 1e12-1e14 Msun at intermediate
redshifts using absorption spectroscopy. Systematic studies of halo gas around
massive galaxies beyond the nearby universe are made possible by large
spectroscopic samples of galaxies and quasars in public archives. In addition
to accurate and precise constraints for the incidence of cool gas in massive
halos, detailed characterizations of gas kinematics and chemical compositions
around massive quiescent galaxies at z ~ 0.5 have also been obtained. Combining
all available measurements shows that infalling clouds from external sources
are likely the primary source of cool gas detected at d >~ 100 kpc from massive
quiescent galaxies. The origin of the gas closer in is currently less certain,
but SNe Ia driven winds appear to contribute significantly to cool gas found at
d < 100 kpc. In contrast, cool gas observed at d <~ 200 kpc from luminous
quasars appears to be intimately connected to quasar activities on parsec
scales. The observed strong correlation between cool gas covering fraction in
quasar host halos and quasar bolometric luminosity remains a puzzle. Combining
absorption-line studies with spatially-resolved emission measurements of both
gas and galaxies is the necessary next step to address remaining questions.


title: A Poynting-Robertson-like drag at the Sun's surface

abstract:
  The Sun's internal rotation {\Omega}(r,{\Theta}) has previously been measured
using helioseismology techniques and found to be a complex function of
co-latitude, {\theta}, and radius, r. From helioseismology and observations of
apparently "rooted" solar magnetic tracers we know that the surface rotates
more slowly than much of the interior. The cause of this slow-down is not
understood but it is important for understanding stellar rotation generally and
any plausible theory of the solar interior. A new analysis using 5-min solar
p-mode limb oscillations as a rotation "tracer" finds an even larger velocity
gradient in a thin region at the top of the photosphere. This shear occurs
where the solar atmosphere radiates energy and angular momentum. We suggest
that the net effect of the photospheric angular momentum loss is similar to
Poynting-Robertson "photon braking" on, for example, Sun-orbiting dust. The
resultant photospheric torque is readily computed and, over the Sun's lifetime,
is found to be comparable to the apparent angular momentum deficit in the
near-surface shear layer.


title: Multi-resolution Data Fusion for Super-Resolution Electron Microscopy

abstract:
  Perhaps surprisingly, the total electron microscopy (EM) data collected to
date is less than a cubic millimeter. Consequently, there is an enormous demand
in the materials and biological sciences to image at greater speed and lower
dosage, while maintaining resolution. Traditional EM imaging based on
homogeneous raster-order scanning severely limits the volume of high-resolution
data that can be collected, and presents a fundamental limitation to
understanding physical processes such as material deformation, crack
propagation, and pyrolysis.
  We introduce a novel multi-resolution data fusion (MDF) method for
super-resolution computational EM. Our method combines innovative data
acquisition with novel algorithmic techniques to dramatically improve the
resolution/volume/speed trade-off. The key to our approach is to collect the
entire sample at low resolution, while simultaneously collecting a small
fraction of data at high resolution. The high-resolution measurements are then
used to create a material-specific patch-library that is used within the
"plug-and-play" framework to dramatically improve super-resolution of the
low-resolution data. We present results using FEI electron microscope data that
demonstrate super-resolution factors of 4x, 8x, and 16x, while substantially
maintaining high image quality and reducing dosage.


title:
How the minuscule can contribute to the big picture: the neutron
  electric dipole moment project at TRIUMF

abstract:
  A permanent electric dipole moment (EDM) of a fundamental particle violates
both parity (P) and time (T) reversal symmetry and combined charge and parity
(CP) reversal symmetry if the combined reversal of charge, parity \textit{and}
time (CPT) is preserved. It is a very promising place to search for physics
beyond the Standard Model. Ultracold neutrons (UCN) are the ideal tool to study
the neutron electric dipole moment since they can be observed for hundreds of
seconds. This article summarizes the current searches for the neutron EDM using
UCN and introduces the project to measure the neutron electric dipole moment at
TRIUMF using its unique accelerator driven spallation neutron and liquid helium
UCN source. The aim is to reach a sensitivity for the neutron EDM of around
$10^{-27} \,e \cdot$cm.


title: FRIDA: FRI-Based DOA Estimation for Arbitrary Array Layouts

abstract:
  In this paper we present FRIDA---an algorithm for estimating directions of
arrival of multiple wideband sound sources. FRIDA combines multi-band
information coherently and achieves state-of-the-art resolution at extremely
low signal-to-noise ratios. It works for arbitrary array layouts, but unlike
the various steered response power and subspace methods, it does not require a
grid search. FRIDA leverages recent advances in sampling signals with a finite
rate of innovation. It is based on the insight that for any array layout, the
entries of the spatial covariance matrix can be linearly transformed into a
uniformly sampled sum of sinusoids.


title:
Bayesian sparse multiple regression for simultaneous rank reduction and
  variable selection

abstract:
  We develop a Bayesian methodology aimed at simultaneously estimating low-rank
and row-sparse matrices in a high-dimensional multiple-response linear
regression model. We consider a carefully devised shrinkage prior on the matrix
of regression coefficients which obviates the need to specify a prior on the
rank, and shrinks the regression matrix towards low-rank and row-sparse
structures. We provide theoretical support to the proposed methodology by
proving minimax optimality of the posterior mean under the prediction risk in
ultra-high dimensional settings where the number of predictors can grow
sub-exponentially relative to the sample size. A one-step post-processing
scheme induced by group lasso penalties on the rows of the estimated
coefficient matrix is proposed for variable selection, with default choices of
tuning parameters. We additionally provide an estimate of the rank using a
novel optimization function achieving dimension reduction in the covariate
space. We exhibit the performance of the proposed methodology in an extensive
simulation study and a real data example.


title: A Novel Approach for Modeling Complex Deep Futures

abstract:
  Many large-scale, complex systems consist of interactions between humans,
human-made systems and the environment. The approach developed in this paper is
to partition the problem space into two fundamental layers and identify,
parameterize and model the main dimensions of each layer and interactions
across and in between layers. One layer is the key actors or major organization
or human decision makers who influence the state of the world. The other layer
includes the domains or fields of knowledge relevant to the problem being
addressed. These domains include elements such as the physical earth and its
atmosphere, world demography, world economy, level of globalization, and
politics. Key parameters for each of the actor types and domains will be
extracted and assessed using existing data sources. Novel systems, uncertainty
modeling and analysis techniques are combined with advanced computational
technologies to determine a spectrum of likely future system states and conduct
ifthen scenario analyses.


title:
Predicting Melting point and Viscosity of Ionic Liquids Using New
  Quantum Chemistry Descriptors

abstract:
  Ionic liquids (ILs) are an emerging group of chemical compounds which possess
promising properties such as having negligible vapor pressure. These so called
designer solvents have the potential to replace volatile organic compounds in
industrial applications. A large number of ILs, through the combination of
different cations and anions, can potentially be synthesized. In this context,
it will be useful to intelligently design customized ILs through computer-aided
methods. Practical limitations dictate that any successful attempt to design
new ILs for industrial applications requires the ability to accurately predict
their melting point and viscosity as experimental data will not be available
for designed structures. In this paper, we present two new correlation
equations towards the more precise prediction of melting point and viscosity of
ILs solely based on the inputs from quantum chemistry calculations (no
experimental data or simulation results are needed). To develop these
correlations we utilized data related to size, shape, and electrostatic
properties of cations and anions that constitutes ILs. In this work, new
descriptors such as dielectric energy of cations and anions as well as the
values predicted by an ad-hoc model for the radii of cations and anions
(instead of their van der waals radii) were used. An enormous form of
correlation equations constituent of all different combinations of descriptors
(as the inputs to the model) were tested. The average relative errors were
measured to be 3.16% and 6.45% for the melting point, Tm, and ln(vis),
respectively.


title:
Magnetic Field Devices for Neutron Spin Transport and Manipulation in
  Precise Neutron Spin Rotation Mesurements

abstract:
  The neutron spin is a critical degree of freedom for many precision
measurements using low-energy neutrons. Fundamental symmetries and interactions
can be studied using polarized neutrons. Parity-violation (PV) in the hadronic
weak interaction and the search for exotic forces that depend on the relative
spin and velocity, are two questions of fundamental physics that can be studied
via the neutron spin rotations that arise from the interaction of polarized
cold neutrons and unpolarized matter. The Neutron Spin Rotation (NSR)
collaboration developed a neutron polarimeter, capable of determining neutron
spin rotations of the order of $10^{-7}$ rad per meter of traversed material.
This paper describes two key components of the NSR apparatus, responsible for
the transport and manipulation of the spin of the neutrons before and after the
target region, which is surrounded by magnetic shielding and where residual
magnetic fields need to be below 100 \textmu G. These magnetic field devices,
called input and output coils, provide the magnetic field for adiabatic
transport of the neutron spin in the regions outside the magnetic shielding
while producing a sharp nonadiabatic transition of the neutron spin when
entering/exiting the low-magnetic-field region. In addition, the coils are self
contained, forcing the return magnetic flux into a compact region of space to
minimize fringe fields outside. The design of the input and output coil is
based on the magnetic scalar potential method.


title:
Procedural Generation of Videos to Train Deep Action Recognition
  Networks

abstract:
  Deep learning for human action recognition in videos is making significant
progress, but is slowed down by its dependency on expensive manual labeling of
large video collections. In this work, we investigate the generation of
synthetic training data for action recognition, as it has recently shown
promising results for a variety of other computer vision tasks. We propose an
interpretable parametric generative model of human action videos that relies on
procedural generation and other computer graphics techniques of modern game
engines. We generate a diverse, realistic, and physically plausible dataset of
human action videos, called PHAV for "Procedural Human Action Videos". It
contains a total of 39,982 videos, with more than 1,000 examples for each
action of 35 categories. Our approach is not limited to existing motion capture
sequences, and we procedurally define 14 synthetic actions. We introduce a deep
multi-task representation learning architecture to mix synthetic and real
videos, even if the action categories differ. Our experiments on the UCF101 and
HMDB51 benchmarks suggest that combining our large set of synthetic videos with
small real-world datasets can boost recognition performance, significantly
outperforming fine-tuning state-of-the-art unsupervised generative models of
videos.


title:
Success Probability of Exploration: a Concrete Analysis of Learning
  Efficiency

abstract:
  Exploration has been a crucial part of reinforcement learning, yet several
important questions concerning exploration efficiency are still not answered
satisfactorily by existing analytical frameworks. These questions include
exploration parameter setting, situation analysis, and hardness of MDPs, all of
which are unavoidable for practitioners. To bridge the gap between the theory
and practice, we propose a new analytical framework called the success
probability of exploration. We show that those important questions of
exploration above can all be answered under our framework, and the answers
provided by our framework meet the needs of practitioners better than the
existing ones. More importantly, we introduce a concrete and practical approach
to evaluating the success probabilities in certain MDPs without the need of
actually running the learning algorithm. We then provide empirical results to
verify our approach, and demonstrate how the success probability of exploration
can be used to analyse and predict the behaviours and possible outcomes of
exploration, which are the keys to the answer of the important questions of
exploration.


title:
Global simulations of protoplanetary disks with net magnetic flux: I.
  Non-ideal MHD case

abstract:
  The planet-forming region of protoplanetary disks is cold, dense, and
therefore weakly ionized. For this reason, magnetohydrodynamic (MHD) turbulence
is thought to be mostly absent, and another mechanism has to be found to
explain gas accretion. It has been proposed that magnetized winds, launched
from the ionized disk surface, could drive accretion in the presence of a
large-scale magnetic field. The efficiency and the impact of these surface
winds on the disk structure is still highly uncertain. We present the first
global simulations of a weakly ionized disk that exhibits large-scale
magnetized winds. We also study the impact of self-organization, which was
previously demonstrated only in non-stratified models. We perform numerical
simulations of stratified disks with the PLUTO code. We compute the ionization
fraction dynamically, and account for all three non-ideal MHD effects: ohmic
and ambipolar diffusions, and the Hall drift. Simplified heating and cooling
due to non-thermal radiation is also taken into account in the disk atmosphere.
We find that disks can be accreting or not, depending on the configuration of
the large-scale magnetic field. Magnetothermal winds, driven both by magnetic
acceleration and heating of the atmosphere, are obtained in the accreting case.
In some cases, these winds are asymmetric, ejecting predominantly on one side
of the disk. The wind mass loss rate depends primarily on the average ratio of
magnetic to thermal pressure in the disk midplane. The non-accreting case is
characterized by a meridional circulation, with accretion layers at the disk
surface and decretion in the midplane. Finally, we observe self-organization,
resulting in axisymmetric rings of density and associated pressure "bumps". The
underlying mechanism and its impact on observable structures are discussed.


title:
On the Angular Momentum of Rockets, Balloons, and Other Variable Mass
  Systems

abstract:
  Variable mass systems are a classic example of open systems in classical
mechanics. The reaction forces due to mass variation propel ships, balloons,
and rockets. Unlike free constant mass systems, the angular momentum of these
systems is not of constant magnitude due to the change in mass. In this paper,
we show that the angular momentum vector for such a system has a fixed
direction in space and, thus, is partially conserved for both rigid and
flexible, torque-free, variable mass systems. A potential use of this result is
that it provides a suitable stationary reference frame against which the
orientation of variable mass system could be measured.


title: Finite remainders of the Konishi at two loops in ${\cal N}=4$ SYM

abstract:
  We present three point form factors (FF) in ${\cal N}=4$ Super Yang Mills
theory for both the half-BPS and the Konishi operators at two loop level in the
`t Hooft coupling using Feynman diagrammatic approach. We have chosen on shell
final states consisting of $g \phi \phi$ and $\phi \lambda \lambda$, where
$\phi,\lambda, g$ are scalar, Majorana fermion and gauge fields respectively.
The computation is done both in the modified dimensional reduction as well as
in the four dimensional helicity scheme. We have studied the universal
structure of infrared (IR) singularities in these FFs using Catani's IR
subtraction operators. Exploiting the factorisation property of the IR
singularities and following BDS like ansatz for the IR sensitive terms in FFs,
we determine the finite remainders of them. We find that the finite remainders
of FFs of the half-BPS for both the choices of final states give not only
identical results but also contain terms of uniform transcendentality of weight
two and four at one and two loop levels, respectively. In the case of the
Konishi operator, the finite remainders depend on the external states and do
not exhibit uniform transcendentality. However, surprisingly, the leading
transcendental terms for $g \phi \phi$ agree with that of the half-BPS. We have
demonstrated the role of on shell external states for the FFs in the context of
maximum transcendentality principle.


title:
New limits on Bosonic Dark Matter, Solar Axions, Pauli Exclusion
  Principle Violation, and Electron Decay from the Majorana Demonstrator

abstract:
  We present new limits on exotic keV-scale physics based on 478 kg d of
MAJORANA DEMONSTRATOR commissioning data. Constraints at the 90% confidence
level are derived on bosonic dark matter (DM) and solar axion couplings, Pauli
exclusion principle violating (PEPV) decay, and electron decay using
monoenergetic peak signal-limits above our background. Our most stringent DM
constraints are set for 11.8 keV mass particles, limiting $g_{Ae} <4.5\times
10^{-13}$ for pseudoscalars and $\frac{\alpha'}{\alpha} < 9.7\times 10^{-28}$
for vectors. We also report a 14.4 keV solar axion coupling limit of
$g_{AN}^{\mathrm{eff}}\times g_{Ae}~<~3.8 \times 10^{-17}$, a
$\frac{1}{2}\beta^2~<~8.5\times10^{-48}$ limit on the strength of PEPV electron
transitions, and a lower limit on the electron lifetime of $\tau_e > 1.2 \times
10^{24}\;$yr for $e^- \rightarrow$ invisible.


title:
Self-assembly of colloidal particles in deformation landscapes of
  electrically driven layer undulations in cholesteric liquid crystals

abstract:
  We study elastic interactions between colloidal particles and deformation
landscapes of undulations in a cholesteric liquid crystal under an electric
field applied normal to cholesteric layers. The onset of undulation instability
is influenced by the presence of colloidal inclusions and, in turn, layers'
undulations mediate the spatial patterning of particle locations. We find that
the bending of cholesteric layers around a colloidal particle surface prompts
the local nucleation of an undulations lattice at electric fields below the
well-defined threshold known for liquid crystals without inclusions, and that
the onset of the resulting lattice is locally influenced, both dimensionally
and orientationally, by the initial arrangements of colloids defined using
laser tweezers. Spherical particles tend to spatially localize in the regions
of strong distortions of the cholesteric layers, while colloidal nanowires
exhibit an additional preference for multistable alignment offset along various
vectors of the undulations lattice. Magnetic rotation of superparamagnetic
colloidal particles couples with the locally distorted helical axis and
undulating cholesteric layers in a manner that allows for a controlled
three-dimensional translation of these particles. These interaction modes lend
insight into the physics of liquid crystal structure-colloid elastic
interactions, as well as point the way towards guided self-assembly of
reconfigurable colloidal composites with potential applications in diffraction
optics and photonics.


title: On The Fundamental Energy Tradeoffs of Geographical Load Balancing

abstract:
  Geographical load balancing can optimize the utilization of green energy and
the cost of electricity by taking the advantages of green and price diversities
at geographical dispersed data centers. However, higher green energy
utilization or lower electricity cost may actually increase the total energy
consumption, and is not necessarily the best option. The achievable energy
tradeoffs can be captured by taking into consideration of a defined service
efficiency parameter for geo-dispersed data centers.


title: New Frameworks for Offline and Streaming Coreset Constructions

abstract:
  Let $P$ be a set (called points), $Q$ be a set (called queries) and a
function $ f:P\times Q\to [0,\infty)$ (called cost). For an error parameter
$\epsilon>0$, a set $S\subseteq P$ with a \emph{weight function} $w:P
\rightarrow [0,\infty)$ is an $\epsilon$-coreset if $\sum_{s\in S}w(s) f(s,q)$
approximates $\sum_{p\in P} f(p,q)$ up to a multiplicative factor of
$1\pm\epsilon$ for every given query $q\in Q$.
  We construct coresets for the $k$-means clustering of $n$ input points, both
in an arbitrary metric space and $d$-dimensional Euclidean space. For Euclidean
space, we present the first coreset whose size is simultaneously independent of
both $d$ and $n$. In particular, this is the first coreset of size $o(n)$ for a
stream of $n$ sparse points in a $d \ge n$ dimensional space (e.g. adjacency
matrices of graphs). We also provide the first generalizations of such coresets
for handling outliers. For arbitrary metric spaces, we improve the dependence
on $k$ to $k \log k$ and present a matching lower bound.
  For $M$-estimator clustering (special cases include the well-known $k$-median
and $k$-means clustering), we introduce a new technique for converting an
offline coreset construction to the streaming setting. Our method yields
streaming coreset algorithms requiring the storage of $O(S + k \log n)$ points,
where $S$ is the size of the offline coreset. In comparison, the previous
state-of-the-art was the merge-and-reduce technique that required $O(S
\log^{2a+1} n)$ points, where $a$ is the exponent in the offline construction's
dependence on $\epsilon^{-1}$. For example, combining our offline and streaming
results, we produce a streaming metric $k$-means coreset algorithm using
$O(\epsilon^{-2} k \log k \log n)$ points of storage. The previous
state-of-the-art required $O(\epsilon^{-4} k \log k \log^{6} n)$ points.


title: Doping dependence of the magnetic excitations in La$_{2-x}$Sr$_x$CuO$_4$

abstract:
  The magnetic correlations within the cuprates have undergone intense scrutiny
as part of efforts to understand high temperature superconductivity. We explore
the evolution of the magnetic correlations along the nodal direction of the
Brillouin zone in La2-xSrxCuO4, spanning the doping phase diagram from the
anti-ferromagnetic Mott insulator at x = 0 to the metallic phase at x = 0.26.
Magnetic excitations along this direction are found to be systematically
softened and broadened with doping, at a higher rate than the excitations along
the anti-nodal direction. This phenomenology is discussed in terms of the
nature of the magnetism in the doped cuprates. Survival of the high energy
magnetic excitations, even in the overdoped regime, indicates that these
excitations are marginal to pairing, while the influence of the low energy
excitations remains ambiguous.


title:
Parameter Compression of Recurrent Neural Networks and Degradation of
  Short-term Memory

abstract:
  The significant computational costs of deploying neural networks in
large-scale or resource constrained environments, such as data centers and
mobile devices, has spurred interest in model compression, which can achieve a
reduction in both arithmetic operations and storage memory. Several techniques
have been proposed for reducing or compressing the parameters for feed-forward
and convolutional neural networks, but less is understood about the effect of
parameter compression on recurrent neural networks (RNN). In particular, the
extent to which the recurrent parameters can be compressed and the impact on
short-term memory performance, is not well understood. In this paper, we study
the effect of complexity reduction, through singular value decomposition rank
reduction, on RNN and minimal gated recurrent unit (MGRU) networks for several
tasks. We show that considerable rank reduction is possible when compressing
recurrent weights, even without fine tuning. Furthermore, we propose a
perturbation model for the effect of general perturbations, such as a
compression, on the recurrent parameters of RNNs. The model is tested against a
noiseless memorization experiment that elucidates the short-term memory
performance. In this way, we demonstrate that the effect of compression of
recurrent parameters is dependent on the degree of temporal coherence present
in the data and task. This work can guide on-the-fly RNN compression for novel
environments or tasks, and provides insight for applying RNN compression in
low-power devices, such as hearing aids.


title: Resolving the $R_{AA}$ to $v_n$ puzzle

abstract:
  After 10 years of struggling to simultaneously describe the nuclear
modification factor $R_{AA}$ and flow harmonics $v_n$'s at high $p_T$, now
theoretical models are able to reproduce experimental data well. The necessary
theoretical developments such as event-by-event fluctuations, choice of initial
conditions, and the scalar product method to calculate flow harmonics at high
$p_T$ are reviewed. Additionally, a discussion of new proposed experimental
observables known as Soft Hard Event Engineering (SHEE) that are sensitive to
the path length dependence of the energy loss is included.


title: The Atacama Large Millimeter/submillimeter Array (ALMA) Band-1 Receiver

abstract:
  The Atacama Large Millimeter/submillimeter Array(ALMA) Band 1 receiver covers
the 35-50 GHz frequency band. Development of prototype receivers, including the
key components and subsystems has been completed and two sets of prototype
receivers were fully tested. We will provide an overview of the ALMA Band 1
science goals, and its requirements and design for use on the ALMA. The
receiver development status will also be discussed and the infrastructure,
integration, evaluation of fully-assembled band 1 receiver system will be
covered. Finally, a discussion of the technical and management challenges
encountered will be presented.


title:
Progress Report on the Measurement of the Carbon Flux in Cosmic Rays
  from 1.9 GV to 2.6 TV with the Alpha Magnetic Spectrometer on the
  International Space Station

abstract:
  Knowledge of the precise rigidity dependence of the carbon flux is important
in understanding the origin, acceleration and propagation of cosmic rays. The
current status of the measurement of the carbon flux in cosmic rays with
rigidity from 1.9 GV to 2.6 TV, based on 8.3 million events collected by the
Alpha Magnetic Spectrometer during the first 5 years of operation, is
presented.


title: Motif Clustering and Overlapping Clustering for Social Network Analysis

abstract:
  Motivated by applications in social network community analysis, we introduce
a new clustering paradigm termed motif clustering. Unlike classical clustering,
motif clustering aims to minimize the number of clustering errors associated
with both edges and certain higher order graph structures (motifs) that
represent "atomic units" of social organizations. Our contributions are
two-fold: We first introduce motif correlation clustering, in which the goal is
to agnostically partition the vertices of a weighted complete graph so that
certain predetermined "important" social subgraphs mostly lie within the same
cluster, while "less relevant" social subgraphs are allowed to lie across
clusters. We then proceed to introduce the notion of motif covers, in which the
goal is to cover the vertices of motifs via the smallest number of (near)
cliques in the graph. Motif cover algorithms provide a natural solution for
overlapping clustering and they also play an important role in latent feature
inference of networks. For both motif correlation clustering and its extension
introduced via the covering problem, we provide hardness results, algorithmic
solutions and community detection results for two well-studied social networks.


title: Rare Event Statistics Applied to Fast Radio Bursts

abstract:
  Statistical interpretation of sparsely sampled event rates has become vital
for new transient surveys, particularly those aimed at detecting fast radio
bursts (FRBs). We provide an accessible reference for a number of simple, but
critical, statistical questions relevant for current transient and FRB research
and utilizing the negative binomial model for counts in which the count rate
parameter is uncertain or randomly biased from one study to the next. We apply
these methods to re-assess and update results from previous FRB surveys,
finding as follows. 1) Thirteen FRBs detected across five
high-Galactic-latitude (> 30$^\circ$) surveys are highly significant $(p =
5\times 10^{-5})$ evidence of a higher rate relative to the single FRB detected
across four low-latitude (< 5$^\circ$) surveys, even after accounting for
effects that dampen Galactic plane sensitivity. High- vs. mid-latitude (5 to
15$^\circ$) is marginally significant $(p = 0.03)$. 2) A meta analysis of
twelve heterogeneous surveys gives an FRB rate of 2866 sky$^{-1}$ day$^{-1}$
above 1 Jy at high Galactic latitude (95% confidence 1121 to 7328) and 285
sky$^{-1}$ day$^{-1}$ at low/mid latitudes (95% from 48 to 1701). 3) Using the
Parkes HTRU high-latitude setup requires 193 observing hours to achieve 50%
probability of detecting an FRB and 937 hours to achieve 95% probability, based
on the ten detections of (Champion et al. 2016) and appropriately accounting
for uncertainty in the unknown Poisson rate. 4) Two quick detections at Parkes
from a small number of high-latitude fields (Ravi et al. 2015; Petroff et al.
2015) tentatively favor a look long survey style relative to the scan wide HTRU
survey, but only at $p = 0.07$ significance.


title:
$k$-additive uniqueness of the set of squares for multiplicative
  functions

abstract:
  P. V. Chung showed that there are many multiplicative functions $f$ which
satisfy $f(m^2+n^2) = f(m^2)+f(n^2)$ for all positive integers $m$ and $n$. In
this article, we show that if more than $2$ squares in the additive condition
are involved, then such $f$ is uniquely determined. That is, if a
multiplicative function $f$ satisfies \[ f(a_1^2 + a_2^2 + \dotsb + a_k^2) =
f(a_1^2) + f(a_2^2) + \dotsb + f(a_k^2) \] for arbitrary positive integers
$a_i$, then $f$ is the identity function. In this sense, we call the set of all
posotive squares a \emph{$k$-additive uniqueness set} for multiplicative
functions.


title:
Asymptotic syzygies grow exponentially: a remark on a paper of
  Ein-Lazarsfeld

abstract:
  For all $2\leq q\leq \dim(X)$ and most relevant $p$ values, the dimension of
the asymptotic Koszul cohomology group $K_{p,q}(X, B;L_d)$ grows exponentially
with $d$.


title: Improved Holographic QCD and the Quark-gluon Plasma

abstract:
  We review construction of the improved holographic models for QCD-like
confining gauge theories and their applications to the physics of the
Quark-gluon plasma. We also review recent progress in this area of research.
The lecture notes start from the vacuum structure of these theories, then
develop thermodynamic and hydrodynamic observables and end with more advanced
topics such as the holographic QCD in the presence of external magnetic fields.
This is a summary of the lectures presented at the 56th Cracow School of
Theoretical Physics in Spring 2016 at Zakopane, Poland.


title: Sum rule study for Double Gamow-Teller states

abstract:
  We study the sum rules of double Gamow-Teller (DGT) excitations through
double spin-isospin operator $(\sigma t_-)^2$. In general, $2^+$ states in the
granddaughter nuclei have dominant transition strength in DGT excitations and
$0^+$ states are weak, except in $T=1$ mother nuclei in which $0^+$ strength is
competitive with 2$^+$ strength. The isospin selection of DGT is also discussed
among 5 possible isospin states in granddaughter nuclei. A possibility to
extract the unit cross section for the DGT transition strength is pointed out
in the $(\sigma t_-)^2$ excitation of double isobaric analog state (DIAS) in
$T=1$ nuclei.


title: Commonly Uncommon: Semantic Sparsity in Situation Recognition

abstract:
  Semantic sparsity is a common challenge in structured visual classification
problems; when the output space is complex, the vast majority of the possible
predictions are rarely, if ever, seen in the training set. This paper studies
semantic sparsity in situation recognition, the task of producing structured
summaries of what is happening in images, including activities, objects and the
roles objects play within the activity. For this problem, we find empirically
that most object-role combinations are rare, and current state-of-the-art
models significantly underperform in this sparse data regime. We avoid many
such errors by (1) introducing a novel tensor composition function that learns
to share examples across role-noun combinations and (2) semantically augmenting
our training data with automatically gathered examples of rarely observed
outputs using web data. When integrated within a complete CRF-based structured
prediction model, the tensor-based approach outperforms existing state of the
art by a relative improvement of 2.11% and 4.40% on top-5 verb and noun-role
accuracy, respectively. Adding 5 million images with our semantic augmentation
techniques gives further relative improvements of 6.23% and 9.57% on top-5 verb
and noun-role accuracy.


title:
Constraining C iii] Emission in a Sample of Five Luminous z = 5.7
  Galaxies

abstract:
  Recent observations have suggested that the CIII]$\lambda1907/1909$ emission
lines could be alternative diagnostic lines for galaxies in the reionization
epoch. We use the F128N narrowband filter on the Hubble Space Telescope's
($\it{HST}$) Wide Field Camera 3 (WFC3) to search for CIII] emission in a
sample of five galaxies at z = 5.7 in the Subaru Deep Field and the
Subaru/XMM-Newton Deep Field. Using the F128N narrowband imaging, together with
the broadband imaging, we do not detect CIII] emission for the five galaxies
with $J_{\rm{AB}}$ ranging from 24.10 -- 27.00 in our sample. For the brightest
galaxy J132416.13+274411.6 in our sample (z = 5.70, $J_{\rm{AB}} = 24.10$),
which has a significantly higher signal to noise, we report a CIII] flux of
$3.34\pm1.81 \times 10^{-18}$ $\mathrm{erg\ s^{-1}\ cm^{-2}}$, which places a
stringent 3-$\rm\sigma$ upper limit of $5.43\times 10^{-18}$ $\mathrm{erg\
s^{-1}\ cm^{-2}}$ on CIII] flux and 6.57 \AA\ on the CIII] equivalent width.
Using the stacked image, we put a 3-$\rm\sigma$ upper limit on the mean CIII]
flux of $\mathrm{2.55\times10^{-18}\ erg\ s^{-1}\ cm^{-2}}$, and a
3-$\rm\sigma$ upper limit on the mean CIII] equivalent width of 4.20 {\AA} for
this sample of galaxies at z = 5.70. Combined with strong CIII] detection
reported among high-z galaxies in the literature, our observations suggest that
the equivalent widths of CIII] from galaxies at z $>$ 5.70 exhibit a wide range
of distribution. Our strong limits on CIII] emission could be used as a guide
for future observations in the reionization epoch.


title: Expander Graph and Communication-Efficient Decentralized Optimization

abstract:
  In this paper, we discuss how to design the graph topology to reduce the
communication complexity of certain algorithms for decentralized optimization.
Our goal is to minimize the total communication needed to achieve a prescribed
accuracy. We discover that the so-called expander graphs are near-optimal
choices. We propose three approaches to construct expander graphs for different
numbers of nodes and node degrees. Our numerical results show that the
performance of decentralized optimization is significantly better on expander
graphs than other regular graphs.


title: Streaming Principal Component Analysis From Incomplete Data

abstract:
  Linear subspace models are pervasive in computational sciences and
particularly used for large datasets which are often incomplete due to privacy
issues or sampling constraints. Therefore, a critical problem is developing an
efficient algorithm for detecting low-dimensional linear structure from
incomplete data efficiently, in terms of both computational complexity and
storage.
  In this paper we propose a streaming subspace estimation algorithm called
Subspace Navigation via Interpolation from Partial Entries (SNIPE) that
efficiently processes blocks of incomplete data to estimate the underlying
subspace model. In every iteration, SNIPE finds the subspace that best fits the
new data block but remains close to the previous estimate. We show that SNIPE
is a streaming solver for the underlying nonconvex matrix completion problem,
that it converges globally to a stationary point of this program regardless of
initialization, and that the convergence is locally linear with high
probability. We also find that SNIPE shows state-of-the-art performance in our
numerical simulations.


title:
Effects of the circularly polarized beam of linearized gravitational
  waves

abstract:
  Solutions of the linearized Einstein equations are found that describe a
transversely confined beam of circularly polarized gravitational waves on a
Minkowski backdrop. By evaluating the cycle-averaged stress-energy-momentum
pseudotensor of Landau & Lifshitz it is found that the angular momentum density
is concentrated in the 'skin' at the edge of the beam where the intensity
falls, and that the ratio of angular momentum to energy per unit length of the
beam is $2/\omega$, where $\omega$ is the wave frequency, as expected for a
beam of spin-$2$ gravitons. For sharply-defined, uniform, axisymmetric beams,
the induced background metric is shown to produce the gravomagnetic field and
frame-dragging effects of a gravitational solenoid, whilst the angular momentum
current additionally twists the contained space helically.


title:
Recovering planet radial velocity signals in the presence of starspot
  activity in fully convective stars

abstract:
  Accounting for stellar activity is a crucial component of the search for
ever-smaller planets orbiting stars of all spectral types. We use Doppler
imaging methods to demonstrate that starspot induced radial velocity
variability can be effectively reduced for moderately rotating, fully
convective stars. Using starspot distributions extrapolated from sunspot
observations, we adopt typical M dwarf starspot distributions with low contrast
spots to synthesise line profile distortions. The distortions are recovered
using maximum entropy regularised fitting and the corresponding stellar radial
velocities are measured. The procedure is demonstrated for a late-M star
harbouring an orbiting planet in the habitable zone. The technique is effective
for stars with vsini = 1-10 km/s, reducing the stellar noise contribution by
factors of nearly an order of magnitude. With a carefully chosen observing
strategy, the technique can be used to determine the stellar rotation period
and is robust to uncertainties such as unknown stellar inclination. While
demonstrated for late-type M stars, the procedure is applicable to all spectral
types.


title: Multigrid In Energy Preconditioner for Krylov Solvers

abstract:
  We have added a new multigrid in energy (MGE) preconditioner to the Denovo
discrete-ordinates radiation transport code. This preconditioner takes
advantage of a new multilevel parallel decomposition. A multigroup Krylov
subspace iterative solver that is decomposed in energy as well as space-angle
forms the backbone of the transport solves in Denovo. The space-angle-energy
decomposition facilitates scaling to hundreds of thousands of cores. The
multigrid in energy preconditioner scales well in the energy dimension and
significantly reduces the number of Krylov iterations required for convergence.
This preconditioner is well-suited for use with advanced eigenvalue solvers
such as Rayleigh Quotient Iteration and Arnoldi.


title: Cutting lemma and Zarankiewicz's problem in distal structures

abstract:
  We establish a cutting lemma for definable families of sets in distal
structures, as well as the optimality of the distal cell decomposition for
definable families of sets on the plane in $o$-minimal expansions of fields.
Using it, we generalize the results in [J. Fox, J. Pach, A. Sheffer, A. Suk,
and J. Zahl. "A semi-algebraic version of Zarankiewicz's problem"] on the
semialgebraic planar Zarankiewicz problem to arbitrary $o$-minimal structures,
in particular obtaining an $o$-minimal generalization of the
Szemer\'edi-Trotter theorem.


title:
Exponential Mixing of Frame Flow for Convex Cocompact Hyperbolic
  Manifolds

abstract:
  The aim of this paper is to establish exponential mixing of frame flow for
the measure of maximal entropy on a convex cocompact hyperbolic manifold.
Consequences include results on the decay of matrix coefficients and on
effective equidistribution of holonomies. The main technical point is a
spectral bound on certain twisted transfer operators, which we obtain by
building on Dolgopyat's framework. This extends and strengthens earlier work of
Dolgopyat, Stoyanov, Pollicott, and others.


title:
First-principles investigation of spin wave dispersions in
  surface-reconstructed Co thin films on W(110)

abstract:
  We computed spin wave dispersions of surface-reconstructed Co films on the
W(110) surface in the adiabatic approximation. The magnetic exchange
interactions are obtained via first-principles electronic structure
calculations using the Korringa-Kohn-Rostoker Green function method. We analyze
the strength and oscillatory behavior of the intralayer and interlayer magnetic
interactions and investigate the resulting spin wave dispersions as a function
of the thickness of Co films. In particular, we highlight and explain the
strong impact of hybridization of the electronic states at the Co-W interface
on the magnetic exchange interactions and on the spin wave dispersions. We
compare our results to recent measurements based on electron energy loss
spectroscopy [E. Michel, H. Ibach, and C.M. Schneider, Phys. Rev. B 92, 024407
(2015)]. Good overall agreement with experimental findings can be obtained by
considering the possible overestimation of the spin splitting, stemming from
the local spin density approximation, and adopting an appropriate correction.


title: Spins in Exotic Nuclei: RI-beam Experiments with Polarized Targets

abstract:
  Spin-degrees of freedom play a significant role in exotic nuclei. Scattering
with polarized protons has potential as a powerful tool to explore the spin
effects in nuclei. This lecture note discusses the background, current status,
and future prospects of experimental studies with spin polarized targets and
radioactive ion beams.


title:
Amplification of nanosecond laser pulse chain via dynamic injection
  locking of laser diode

abstract:
  We report a novel optical pulse generation method for high-speed wavelength
switching of amplified nanosecond (ns) laser pulses resonant to atomic
transitions.Under free-running condition, a slave laser diode is blue-detuned
with tens of GHz relative to the master laser. A ns pulse chain generated by
modulating the continuous-wave master laser with a fiber-pigtailed
electro-optical intensity modulator is injected into the slave laser diode to
fast switch the slave laser's wavelength back and forth. The output beam of
slave laser is filtered by a temperature-controlled etalon to get the amplified
pulse chain. Based on our dynamic injection locking scheme, we produce a
ns-scale square pulse chain with an effective ON/OFF ratio 10^8, considering at
least the 60 dB scattering suppression by tuning light-atom interactions with
far off-resonance detuning and 26.7 dB suppression ratio of the etalon. By
studying the dynamic processes of injection locking, we determine the
dependence of injection locking on both the injection power and the frequency
detuning.


title:
End-to-End Joint Learning of Natural Language Understanding and Dialogue
  Manager

abstract:
  Natural language understanding and dialogue policy learning are both
essential in conversational systems that predict the next system actions in
response to a current user utterance. Conventional approaches aggregate
separate models of natural language understanding (NLU) and system action
prediction (SAP) as a pipeline that is sensitive to noisy outputs of
error-prone NLU. To address the issues, we propose an end-to-end deep recurrent
neural network with limited contextual dialogue memory by jointly training NLU
and SAP on DSTC4 multi-domain human-human dialogues. Experiments show that our
proposed model significantly outperforms the state-of-the-art pipeline models
for both NLU and SAP, which indicates that our joint model is capable of
mitigating the affects of noisy NLU outputs, and NLU model can be refined by
error flows backpropagating from the extra supervised signals of system
actions.


title: Some ternary cubic two-weight codes

abstract:
  We study trace codes with defining set $L,$ a subgroup of the multiplicative
group of an extension of degree $m$ of the alphabet ring
$\mathbb{F}_3+u\mathbb{F}_3+u^{2}\mathbb{F}_{3},$ with $u^{3}=1.$ These codes
are abelian, and their ternary images are quasi-cyclic of co-index three
(a.k.a. cubic codes). Their Lee weight distributions are computed by using
Gauss sums. These codes have three nonzero weights when $m$ is singly-even and
$|L|=\frac{3^{3m}-3^{2m}}{2}.$ When $m$ is odd, and
$|L|=\frac{3^{3m}-3^{2m}}{2}$, or $|L|={3^{3m}-3^{2m}}$ and $m$ is a positive
integer, we obtain two new infinite families of two-weight codes which are
optimal. Applications of the image codes to secret sharing schemes are also
given.


title: New Classes of $p$-ary Few Weights Codes

abstract:
  In this paper, several classes of three-weight codes and two-weight codes for
the homogeneous metric over the chain ring $R=\mathbb{F}_p+u\mathbb{F}_p+\cdots
+u^{k-1}\mathbb{F}_{p},$ with $u^k=0,$ are constructed, which generalises
\cite{SL}, the special case of $p=k=2.$ These codes are defined as trace codes.
In some cases of their defining sets, they are abelian. Their homogeneous
weight distributions are computed by using exponential sums. In particular, in
the two-weight case, we give some conditions of optimality of their Gray images
by using the Griesmer bound. Their dual homogeneous distance is also given. The
codewords of these codes are shown to be minimal for inclusion of supports, a
fact favorable to an application to secret sharing schemes.


title: A Matrix Splitting Perspective on Planning with Options

abstract:
  We show that the Bellman operator underlying the options framework leads to a
matrix splitting, an approach traditionally used to speed up convergence of
iterative solvers for large linear systems of equations. Based on standard
comparison theorems for matrix splittings, we then show how the asymptotic rate
of convergence varies as a function of the inherent timescales of the options.
This new perspective highlights a trade-off between asymptotic performance and
the cost of computation associated with building a good set of options.


title: Average Entropy of the Ranges for Simple Random Walks on Discrete Groups

abstract:
  Inspired by Benjamini et al (Ann. Inst. H. Poincar\'{e} Probab. Stat. 2010)
and Windisch (Electron. J. Probab. 2010), we consider the entropy of the random
walk range formed by a simple random walk on a discrete group. It is shown in
this setting the existence of a quantity which we call the average entropy of
the ranges. Some equivalent conditions for the vanishing of the average entropy
of the ranges are given. Particularly, the average entropy of the ranges
vanishes if and only if the random walk is recurrent or escaping to negative
infinity without left jump. In order to characterize the recurrence further, we
study the average entropy of the weighted digraphs formed by the random walk.
We show that the random walk is recurrent if and only if the average entropy of
the weighted digraphs vanishes.


title:
High-Energy Neutrino Flares From X-Ray Bright and Dark Tidal Disruptions
  Events

abstract:
  X-ray and $\gamma$-ray observations by the Swift satellite revealed that a
fraction of tidal disruption events (TDEs) have relativistic jets. Jetted TDEs
have been considered as potential sources of very high-energy cosmic-rays and
neutrinos. In this work, using semi-analytical methods, we calculate neutrino
spectra of X-ray bright TDEs with powerful jets and dark TDEs with possible
choked jets, respectively. We estimate their neutrino fluxes and find that the
non-detection would give us an upper limit on the cosmic-ray loading factor,
$\xi_{\rm cr}\lesssim20$, for Sw J1644+57. We show that X-ray bright TDEs make
a sub-dominant ($\lesssim5-10$%) contribution to IceCube's diffuse neutrino
flux, and study possible contributions of X-ray dark TDEs given that particles
are accelerated in choked jets or disk-winds. We discuss future prospects for
multi-messenger searches of the brightest TDEs.


title:
A Group of Immersed Finite Element Spaces For Elliptic Interface
  Problems

abstract:
  We present a unified framework for developing and analysing immersed finite
element (IFE) spaces for solving typical elliptic interface problems with
interface independent meshes. This framework allows us to construct a group of
new IFE spaces with either linear, or bilinear, or the rotated-Q1 polynomials.
Functions in these IFE spaces are locally piecewise polynomials defined
according to the sub-elements formed by the interface itself instead of its
line approximation. We show that the unisolvence for these IFE spaces follows
from the invertibility of the Sherman-Morrison matrix. A group of estimates and
identities are established for the interface geometry and shape functions that
are applicable to all of these IFE spaces. Most importantly, these fundamental
preparations enable us to develop a unified multipoint Taylor expansion
procedure for proving that these IFE spaces have the expected optimal
approximation capability according to the involved polynomials.


title: Collaborative visual analytics of radio surveys in the Big Data era

abstract:
  Radio survey datasets comprise an increasing number of individual
observations stored as sets of multidimensional data. In large survey projects,
astronomers commonly face limitations regarding: 1) interactive visual
analytics of sufficiently large subsets of data; 2) synchronous and
asynchronous collaboration; and 3) documentation of the discovery workflow. To
support collaborative data inquiry, we present encube, a large-scale
comparative visual analytics framework. Encube can utilise advanced
visualization environments such as the CAVE2 (a hybrid 2D and 3D virtual
reality environment powered with a 100 Tflop/s GPU-based supercomputer and 84
million pixels) for collaborative analysis of large subsets of data from radio
surveys. It can also run on standard desktops, providing a capable visual
analytics experience across the display ecology. Encube is composed of four
primary units enabling compute-intensive processing, advanced visualisation,
dynamic interaction, parallel data query, along with data management. Its
modularity will make it simple to incorporate astronomical analysis packages
and Virtual Observatory capabilities developed within our community. We discuss
how encube builds a bridge between high-end display systems (such as CAVE2) and
the classical desktop, preserving all traces of the work completed on either
platform -- allowing the research process to continue wherever you are.


title: Local well-posedness of the Camassa-Holm equation on the real line

abstract:
  In this paper we prove the local well-posedness of the Camassa-Holm equation
on the real line in the space of continuously differentiable diffeomorphisms
with an appropriate decaying condition. This work was motivated by G. Misiolek
who proved the same result for the Camassa-Holm equation on the periodic
domain. We use the Lagrangian approach and rewrite the equation as an ODE on
the Banach space. Then by using the standard ODE technique, we prove existence
and uniqueness. Finally, we show the continuous depdendence of the solution on
the initial data by using the topological group property of the diffeomorphism
group.


title:
An efficient and doubly robust empirical likelihood approach for
  estimating equations with missing data

abstract:
  This paper considers an empirical likelihood inference for parameters defined
by general estimating equations, when data are missing at random. The
efficiency of existing estimators depends critically on correctly specifying
the conditional expectation of the estimating function given the observed
components of the random observations. When the conditional expectation is not
correctly specified, the efficiency of estimation can be severely compromised
even if the propensity function (of missingness) is correctly specified. We
propose an efficient estimator which enjoys the double-robustness property and
can achieve the semiparametric efficiency bound within the class of the
estimating functions that are generated by the estimating function of
estimating equations, if both the propensity model and the regression model (of
the conditional expectation) are specified correctly. Moreover, if the
propensity model is specified correctly but the regression model is
misspecified, the proposed estimator still achieves a semiparametric efficiency
lower bound within a more general class of estimating functions. Simulation
results suggest that the proposed estimators are robust against
misspecification of the propensity model or regression model and outperform
many existing competitors in the sense of having smaller mean-square errors.
Moreover, using our approach for statistical inference requires neither
resampling nor kernel smoothing. A real data example is used to illustrate the
proposed approach.


title: The nuclear contacts and short range correlations in nuclei

abstract:
  Atomic nuclei are complex strongly interacting systems and their exact
theoretical description is a long-standing challenge. An approximate
description of nuclei can be achieved by separating its short and long range
structure. This separation of scales stands at the heart of the nuclear shell
model and effective field theories that describe the long-range structure of
the nucleus using a mean- field approximation. We present here an effective
description of the complementary short-range structure using contact terms and
stylized two-body asymptotic wave functions. The possibility to extract the
nuclear contacts from experimental data is presented. Regions in the two-body
momentum distribution dominated by high-momentum, close-proximity, nucleon
pairs are identified and compared to experimental data. The amount of
short-range correlated (SRC) nucleon pairs is determined and compared to
measurements. Non-combinatorial isospin symmetry for SRC pairs is identified.
The obtained one-body momentum distributions indicate dominance of SRC pairs
above the nuclear Fermi-momentum.


title:
Global classical solutions, stability of constant equilibria, and
  spreading speeds in attraction-repulsion chemotaxis systems with logistic
  source on $\mathbb{R}^{N}$

abstract:
  We consider the following chemotaxis systems $$\begin{cases}u_t=\Delta
u-\chi_1\nabla(u\nabla v_1)+\chi_2\nabla(u\nabla v_2)+u(a-bu),\ \ x\in\mathbb
R^N,t>0,\\0=(\Delta-\lambda_1I)v_1+\mu_1u,\ \ x\in\mathbb
R^N,t>0,\\0=(\Delta-\lambda_2I)v_2+\mu_2u,\ \ \text{in}\ x\in\mathbb R^N,\
t>0,\\u(\cdot,0)=u_0,\ \ x\in\mathbb R^N,\end{cases}$$where $\chi_i,\
\lambda_i,\ \mu_i,\ i=1,2$ and $a,\ b$ are positive constant real numbers and
$N$ is a positive integer. Under some conditions on the parameters, we prove
the global existence and boundedness of classical solutions
$(u(x,t;u_0),v_1(x,t;u_0),v_2(x,t;u_0))$ for nonnegative, bounded, and
uniformly continuous initials $u_0(x)$. Next, we show that, for every strictly
positive initial
\,$u_0(x)$,$$\lim_{t\to\infty}\left[\|u(\cdot,t;u_0)-\frac{a}{b}\|_{\infty}+\|\lambda_1v_1(\cdot,t;u_0)-\frac{a}{b}\mu_1\|_{\infty}+\|\lambda_2v_2(\cdot,t;u_0)-\frac{a}{b}\mu_2\|_{\infty}\right]=0.$$
Finally, we explore the spreading properties of the global solutions and prove
that there are two positive numbers
$0<c^*_-(\chi_1,\mu_1,\lambda_1,\chi_2,\mu_2,\lambda_2)<c^*_+(\chi_1,\mu_1,\lambda_1,\chi_2,\mu_2,\lambda_2)$
such that for every nonegative initial $u_0(x)$ with nonempty and compact
support,
$$\lim_{t\to\infty}\left[\sup_{|x|\leq{ct}}|u(x,t;u_0)-\frac{a}{b}|+\sup_{|x|\leq
ct}|\lambda_1v_1(x,t;u_0)-\frac{a}{b}\mu_1|+\sup_{|x|\leq
ct}|\lambda_2v_2(x,t;u_0)-\frac{a}{b}\mu_2|\right]=0$$whenever $0\leq
c<c^*_-(\chi_1,\mu_1,\lambda_1,\chi_2,\mu_2,\lambda_2)$,\
and$$\lim_{t\to\infty}\left[\sup_{|x|\geq ct}|u(x,t;u_0)|+\sup_{|x|\geq ct} |
v_1(x,t;u_0)|+\sup_{|x|\geq ct}|v_2(x,t;u_0)|\right]=0$$whenever
$c>c^*_+(\chi_1,\mu_1,\lambda_1,\chi_2,\mu_2,\lambda_2)$. Furthermore we show
that$$\lim_{(\chi_1,\chi_2)\to(0,0)}c^*_-(\chi_1,\mu_1,\lambda_1,\chi_2,\mu_2,\lambda_2)=\lim_{(\chi_1,\chi_2)\to(0,0)}c^*_+(\chi_1,\mu_1,\lambda_1,\chi_2,\mu_2,\lambda_2)=2\sqrt{a}.$$


title: Siegel Paramodular Forms of Weight 2 and Squarefree Level

abstract:
  We compute the space $S_2(K(N))$ of weight $2$ Siegel paramodular cusp forms
of squarefree level $N<300$. In conformance with the paramodular conjecture of
A. Brumer and K. Kramer, the space is only the additive (Gritsenko) lift space
of the Jacobi cusp form space $J_{2,N}^{\text{cusp}}$ except for $N=249,295$,
when it further contains one nonlift newform. For these two values of $N$, the
Hasse-Weil $p$-Euler factors of a relevant abelian surface match the spin
$p$-Euler factors of the nonlift newform for the first two primes $p\nmid N$.


title: Complex Hadamard matrices attached to even orthogonal schemes of class 4

abstract:
  A complex Hadamard matrix is a square matrix W with complex entries of
absolute value 1 satisfying WW*=nI, where * stands for the Hermitian transpose
and I is the identity matrix of order n. In this paper, we give constructions
of complex Hadamard matrices in the Bose-Mesner algebra of a certain 4-class
symmetric association scheme. Moreover, we determine the Nomura algebras to
show that the resulting matrices are not decomposable into nontrivial
generalized tensor products.


title:
Simplified Expressions of the Multi-Indexed Laguerre and Jacobi
  Polynomials

abstract:
  The multi-indexed Laguerre and Jacobi polynomials form a complete set of
orthogonal polynomials. They satisfy second-order differential equations but
not three term recurrence relations, because of the 'holes' in their degrees.
The multi-indexed Laguerre and Jacobi polynomials have Wronskian expressions
originating from multiple Darboux transformations. For the ease of
applications, two different forms of simplified expressions of the
multi-indexed Laguerre and Jacobi polynomials are derived based on various
identities. The parity transformation property of the multi-indexed Jacobi
polynomials is derived based on that of the Jacobi polynomial.


title: Peer Prediction with Heterogeneous Tasks

abstract:
  Peer prediction is a method to promote contributions of information by users
in settings in which there is no way to verify the quality of responses. In
multi-task peer prediction, the reports from users across multiple tasks are
used to score contributions. This paper extends the correlated agreement (CA)
multi-task peer prediction mechanism to allow the reports from users to be on
heterogeneous tasks, each associated with different distributions on responses.
The motivation comes from wanting to elicit user-generated content about places
in a city, where tasks vary because places, and questions about places, vary.
We prove that the generalized CA mechanism is informed truthful under weak
conditions, meaning that it is strictly beneficial for a user to invest effort
and acquire information, and that truthful reporting is the best strategy when
investing effort, as well as an equilibrium. We demonstrate that the mechanism
has good incentive properties when tested in simulation on distributions
derived from user reports on Google Local Guides.


title:
Gauge symmetry breaking in the adiabatic self-consistent collective
  coordinate method

abstract:
  We study gauge symmetry breaking by adiabatic approximation in the adiabatic
self-consistent collective coordinate (ASCC) method. In the previous study, we
found that the gauge symmetry of the equation of collective submanifold is
(partially) broken by its decomposition into the three moving-frame equations
depending on the order of $p$. In this study, we discuss the gauge symmetry
breaking by the truncation of the adiabatic expansion. A particular emphasis is
placed on the symmetry under the gauge transformations which are not point
transformations. We also discuss a possible version of the ASCC method
including the higher-order operators which can keep the gauge symmetry.


title: Quasi-Elliptic Cohomology and its Power Operations

abstract:
  Quasi-elliptic cohomology is a variant of Tate K-theory. It is the orbifold
K-theory of a space of constant loops. For global quotient orbifolds, it can be
expressed in terms of equivariant K-theories. In this paper we show how this
theory is equipped with power operations. We also prove that the Tate K-theory
of symmetric groups modulo a certain transfer ideal classify the finite
subgroups of the Tate curve.


title:
Evaluating continuum solvation models for the electrode-electrolyte
  interface: challenges and strategies for improvement

abstract:
  Ab initio modeling of electrochemical systems is becoming a key tool for
understanding and predicting electrochemical behavior. Development and careful
benchmarking of computational electrochemical methods are essential to ensure
their accuracy. Here, using charging curves for an electrode in the presence of
an inert aqueous electrolyte, we demonstrate that most continuum models, which
are parameterized and benchmarked for molecules, anions, and cations in
solution, undersolvate metal surfaces, and underestimate the surface charge as
a function of applied potential. We examine features of the electrolyte and
interface that are captured by these models, and identify improvements
necessary for realistic electrochemical calculations of metal surfaces.
Finally, we reparameterize popular solvation models using the surface charge of
Ag(100) as a function of voltage to find improved accuracy for metal surfaces
without significant change in utility for molecular and ionic solvation.


title: Quaternionic Fock space in an Euclidean unit ball $\mathbb{B}^n$

abstract:
  In this paper, we study the quaternionic counterpart of complex Fock spaces
$\mathfrak{F}_{\alpha}^p ( 0<p<\infty$ and for some parameter $\alpha$) of
entire slice hyperholomorphic functions in an Euclidean unit ball
$\mathbb{B}^n$ in $\mathbb{H}^n.$ We also study some basic properties of these
spaces.


title:
Analysis and Design of a Passive Switched-Capacitor Matrix Multiplier
  for Approximate Computing

abstract:
  A switched-capacitor matrix multiplier is presented for approximate computing
and machine learning applications. The multiply-and-accumulate operations
perform discrete-time charge-domain signal processing using passive switches
and 300 aF unit capacitors. The computation is digitized with a 6 b
asynchronous successive approximation register analog-to-digital converter. The
analyses of incomplete charge accumulation and thermal noise are discussed. The
design was fabricated in 40 nm CMOS, and experimental measurements of
multiplication are illustrated using matched filtering and image convolutions
to analyze noise and offset. Two applications are highlighted: 1)
energy-efficient feature extraction layer performing both compression and
classification in a neural network for an analog front end and 2) analog
acceleration for solving optimization problems that are traditionally performed
in the digital domain. The chip obtains measured efficiencies of 8.7 TOPS/W at
1 GHz for the first application and 7.7 TOPS/W at 2.5 GHz for the second
application.


title:
Kaplansky's zero divisor and unit conjectures on elements with supports
  of size $3$

abstract:
  Kaplansky's zero divisor conjecture (unit conjecture, respectively) states
that for a torsion-free group $G$ and a field $\mathbb{F}$, the group ring
$\mathbb{F}[G]$ has no zero divisors (has no unit with support of size greater
than $1$). In this paper, we study possible zero divisors and units in
$\mathbb{F}[G]$ whose supports have size $3$. For any field $\mathbb{F}$ and
all torsion-free groups $G$, we prove that if $\alpha \beta=0$ for some
non-zero $\alpha, \beta \in \mathbb{F}[G]$ such that $|supp(\alpha)|=3$, then
$|supp(\beta)|\geq 10$. If $\mathbb{F}=\mathbb{F}_2$ is the field with 2
elements, the latter result can be improved so that $|supp(\beta)|\geq 20$.
This improves a result in [J. Group Theory, 16 (2013), no. 5, 667-693].
Concerning the unit conjecture, we prove that if $\alpha \beta=1$ for some
$\alpha, \beta \in \mathbb{F}[G]$ such that $|supp(\alpha)|=3$, then
$|supp(\beta)|\geq 9$. The latter improves a part of a result in [Exp. Math.,
24 (2015), 326-338] to arbitrary fields.


title:
Micro-engineered CH$_3$NH$_3$PbI$_3$ nanowire/graphene phototransistor
  for low intensity light detection at room temperature

abstract:
  Methylammonium lead iodide perovskite has revolutionized the field of third
generation solid-state solar cells leading to simple solar cell structures1 and
certified efficiencies up to 20.1%. Recently the peculiar light harvesting
properties of organometal halide perovskites have been exploited in
photodetectors where responsivities of ~3.5 A/W and 180 A/W have been
respectively achieved for pure perovskite-based devices and hybrid
nanostructures. Here, we report on the first hybrid phototransistors where the
performance of a network of photoactive Methylammonium Lead Iodide nanowires
(hereafter MAPbI$_3$NW) are enhanced by CVD-grown monolayer graphene. These
devices show responsivities as high as ~2.6x10$^6$ A/W in the visible range
showing potential as room-temperature single-electron detector.


title: Heterogeneous Distributed Average Tracking

abstract:
  This paper addresses distributed average tracking for a group of
heterogeneous physical agents consisting of single-integrator,
double-integrator and Euler-Lagrange dynamics. Here, the goal is that each
agent uses local information and local interaction to calculate the average of
individual time-varying reference inputs, one per agent. Two nonsmooth
algorithms are proposed to achieve the distributed average tracking goal. In
our first proposed algorithm, each agent tracks the average of the reference
inputs, where each agent is required to have access to only its own position
and the relative positions between itself and its neighbors. To relax the
restrictive assumption on admissible reference inputs, we propose the second
algorithm. A filter is introduced for each agent to generate an estimation of
the average of the reference inputs. Then, each agent tracks its own generated
signal to achieve the average tracking goal in a distributed manner. Finally,
numerical example is included for illustration.


title: Generalising a finite version of Euler's partition identity

abstract:
  Recently, George Andrews has given a Glaisher style proof of a finite version
of Euler's partition identity. We generalise this result by giving a finite
version of Glaisher's partition identity. Both the generating function and
bijective proofs are presented.


title:
Anisotropic magneto-transport and magnetic properties of low temperature
  phase of TaTe2

abstract:
  TaTe2 is a quasi-2D charge density wave (CDW) compound with distorted-1T type
structure exhibiting double-zigzag chains. Here we report the Fermi surface
topology of low temperature phase of TaTe2 (LT-TaTe2) by anisotropic
magneto-transport and magnetic measurements on high-quality single crystals. An
anomalous large linear magnetoresistance up to 140% at 3 K in 9 T was observed,
suggesting the existence of a small Fermi pocket in Dirac cone state in quantum
transport models. Meanwhile, strong magnetic anisotropy was observed for B
(001) and B//(001). Angle-dependent magnetoresistance and de Hass-van Alphen
oscillations suggest the anisotropy of the normal Fermi surface and the small
Fermi pocket in Dirac cone state.


title:
Projection Sparse Principal Component Analysis: an efficient least
  squares method

abstract:
  We propose a new sparse principal component analysis (SPCA) method in which
the solutions are obtained by projecting the full cardinality principal
components onto subsets of variables. The resulting components are guaranteed
to explain a given proportion of variance. The computation of these solutions
is very efficient. The proposed method compares well with the optimal least
squares sparse components. We show that other SPCA methods fail to identify the
best sparse approximations of the principal components and explain less
variance than our solutions. We illustrate and compare our method with the
analysis of a real dataset containing socioeconomic data and the computational
results for nine datasets of increasing dimension with up to 16,000 variables.


title: End-to-end learning of brain tissue segmentation from imperfect labeling

abstract:
  Segmenting a structural magnetic resonance imaging (MRI) scan is an important
pre-processing step for analytic procedures and subsequent inferences about
longitudinal tissue changes. Manual segmentation defines the current gold
standard in quality but is prohibitively expensive. Automatic approaches are
computationally intensive, incredibly slow at scale, and error prone due to
usually involving many potentially faulty intermediate steps. In order to
streamline the segmentation, we introduce a deep learning model that is based
on volumetric dilated convolutions, subsequently reducing both processing time
and errors. Compared to its competitors, the model has a reduced set of
parameters and thus is easier to train and much faster to execute. The contrast
in performance between the dilated network and its competitors becomes obvious
when both are tested on a large dataset of unprocessed human brain volumes. The
dilated network consistently outperforms not only another state-of-the-art deep
learning approach, the up convolutional network, but also the ground truth on
which it was trained. Not only can the incredible speed of our model make large
scale analyses much easier but we also believe it has great potential in a
clinical setting where, with little to no substantial delay, a patient and
provider can go over test results.


title: Linear measure and $K$-quasiconformal harmonic mappings

abstract:
  In this paper, we investigate the relationships between linear measure and
harmonic mappings.


title:
Hybrid quantum device with a carbon nanotube and a flux qubit for
  dissipative quantum engineering

abstract:
  We describe a hybrid quantum system composed of a micrometer-size carbon
nanotube (CNT) longitudinally coupled to a flux qubit. We demonstrate the
usefulness of this device for generating high-fidelity nonclassical states of
the CNT via dissipative quantum engineering. Sideband cooling of the CNT to its
ground state and generating a squeezed ground state, as a mechanical analogue
of the optical squeezed vacuum, are two additional examples of the dissipative
quantum engineering studied here. Moreover, we show how to generate a
long-lived macroscopically-distinct superposition (i.e., a Schr\"odinger
cat-like) state. This cat state can be trapped, under some conditions, in a
dark state, as can be verified by detecting the optical response of control
fields.


title: A note on Matching Cover Algorithm

abstract:
  A $k$-matching cover of a graph $G$ is a union of $k$ matchings of $G$ which
covers $V(G)$. A matching cover of $G$ is optimal if it consists of the fewest
matchings of $G$. In this paper, we present an algorithm for finding an optimal
matching cover of a graph on $n$ vertices and $m$ edges in $O(nm)$ time. This
algorithm corrects an error of Matching Cover Algorithm in (Xiumei Wang,
Xiaoxin Song, Jinjiang Yuan, On matching cover of graphs, Math. Program. Ser. A
(2014)147: 499-518).


title: Using Discourse Signals for Robust Instructor Intervention Prediction

abstract:
  We tackle the prediction of instructor intervention in student posts from
discussion forums in Massive Open Online Courses (MOOCs). Our key finding is
that using automatically obtained discourse relations improves the prediction
of when instructors intervene in student discussions, when compared with a
state-of-the-art, feature-rich baseline. Our supervised classifier makes use of
an automatic discourse parser which outputs Penn Discourse Treebank (PDTB) tags
that represent in-post discourse features. We show PDTB relation-based features
increase the robustness of the classifier and complement baseline features in
recalling more diverse instructor intervention patterns. In comprehensive
experiments over 14 MOOC offerings from several disciplines, the PDTB discourse
features improve performance on average. The resultant models are less
dependent on domain-specific vocabulary, allowing them to better generalize to
new courses.