title:
An Experiment to Demonstrate Separation of Cherenkov and Scintillation
  Signals

abstract:
  The ability to separately identify the Cherenkov and scintillation light
components produced in scintillating mediums holds the potential for a major
breakthrough in neutrino detection technology, allowing development of a large,
low-threshold, directional detector with a broad physics program. The CHESS
(CHErenkov / Scintillation Separation) experiment employs an innovative
detector design with an array of small, fast photomultiplier tubes and
state-of-the-art electronics to demonstrate the reconstruction of a Cherenkov
ring in a scintillating medium based on photon hit time and detected
photoelectron density. This paper describes the physical properties and
calibration of CHESS along with first results. The ability to reconstruct
Cherenkov rings is demonstrated in a water target, and a time precision of 338
+/- 12 ps FWHM is achieved. Monte Carlo based predictions for the ring imaging
sensitivity with a liquid scintillator target predict an efficiency for
identifying Cherenkov hits of 94 +/- 1% and 81 +/- 1% in pure linear alkyl
benzene (LAB) and LAB loaded with 2 g/L of PPO, respectively, with a
scintillation contamination of 12 +/- 1% and 26 +/- 1%.


title:
Detection of a dearth of stars with zero angular momentum in the solar
  neighbourhood

abstract:
  We report on the detection in the combined $Gaia$-DR1/RAVE data of a lack of
disk stars in the solar neighbourhood with velocities close to zero angular
momentum. We propose that this may be caused by the scattering of stars with
very low angular momentum onto chaotic, halo-type orbits when they pass through
the Galactic nucleus. We model the effect in a Milky-Way like potential and fit
the resulting model directly to the data, finding a likelihood
($\sim2.7\sigma$) of a dip in the distribution. Using this effect, we can make
a dynamical measurement of the Solar rotation velocity around the Galactic
center: $v_{\odot}=239\pm9$ km s$^{-1}$. Combined with the measured proper
motion of Sgr A$^*$, this measurement gives a measurement of the distance to
the Galactic centre: $R_0=7.9\pm0.3$ kpc.


title:
The Asymptotic Form of Non-Global Logarithms, Black Disc Saturation, and
  Gluonic Deserts

abstract:
  We develop an asymptotic perturbation theory for the large logarithmic
behavior of the non-linear integro-differential equation describing the soft
correlations of QCD jet measurements, the Banfi-Marchesini-Smye (BMS) equation.
This equation captures the late-time evolution of radiating color dipoles after
a hard collision. This allows us to prove that at large values of the control
variable (the non-global logarithm, a function of the infra-red energy scales
associated with distinct hard jets in an event), the distribution has a
gaussian tail. We compute the decay width analytically, giving a closed form
expression, and find it to be jet geometry independent, up to the number of
legs of the dipole in the active jet. Enabling the asymptotic expansion is the
correct perturbative seed, where we perturb around an anzats encoding formally
no real emissions, an intuition motivated by the buffer region found in jet
dynamics. This must be supplemented with the correct application of the BFKL
approximation to the BMS equation in collinear limits. Comparing to the
asymptotics of the conformally related evolution equation encountered in
small-x physics, the Balitisky-Kovchegov (BK) equation, we find that the
asymptotic form of the non-global logarithms directly maps to the black-disc
unitarity limit of the BK equation, despite the contrasting physical pictures.
Indeed, we recover the equations of saturation physics in the final state
dynamics of QCD.


title:
Environmental noise effects on entanglement fidelity of exchange-coupled
  semiconductor spin qubits

abstract:
  We investigate the effect of magnetic field and charge noise on the
generation of entanglement between two Heisenberg exchange-coupled electron
spins in a double quantum dot. We focus on exchange-driven evolution that would
ideally take an initial unentangled tensor product state to a
maximally-entangled state in the absence of noise. The presence of noise
obviously adversely affects the attainment of maximal entanglement, which we
study quantitatively and exactly. To quantify the effects of noise, we
calculate two-qubit coherence times and entanglement fidelity, both of which
can be extracted from simulations or measurements of the return probability as
a function of interaction time, i.e., the time period during which the exchange
coupling remains effective between the two spins. We perform these calculations
for a broad range of noise strengths that includes the regime of recent
experiments. We find that the two types of noise reduce the amount of
entanglement in qualitatively distinct ways and that, although charge noise
generally leads to faster decoherence, the relative importance of the two types
of noise in entanglement creation depends sensitively on the strength of the
exchange coupling. Our results can be used to determine the level of noise
suppression needed to reach quantum error correction thresholds. We provide
quantitative guidance for the requisite noise constraints necessary to
eventually reach the $>99\%$ fidelity consistent with the quantum error
correction threshold.


title: Causality Constraints on Massive Gravity

abstract:
  The de Rham-Gabadadze-Tolley massive gravity admits pp-wave backgrounds on
which linear fluctuations are shown to undergo time advances for all values of
the parameters. The perturbations may propagate in closed time-like curves
unless the parameter space is constrained to a line. These classical phenomena
take place well within the theory's validity regime.


title: The Stellar Density Profile of the Distant Galactic Halo

abstract:
  We use extensive gravity-sensitive DDO 51 photometry over 5100 square
degrees, combined with SDSS broadband photometry, to select a catalog of $\sim
4,000$ giant stars covering a large fraction of the high Galactic latitude sky
and reaching out to $\sim 80$ kpc in the Galactic halo. This sample of bright
and unbiased tracers enables us to measure the radial profile and 3D structure
of the stellar halo to large distance which had previously only been measured
with sparse tracers or small samples. Using population synthesis models to
reproduce the observed giant star luminosity function, we find that the halo
maintains a $r^{-3.5}$ profile from $30$ to $80$ kpc with no signs of a
truncation or sharp break over this range. The radial profile measurement is
largely insensitive to individual halo substructure components, but we find
that attempting to measure the shape of the halo is overwhelmed by the
Sagittarius stream such that no ellipsoidal shape is a satisfactory description
in this region. These measurements allow us to begin placing the Milky Way in
context with the growing sample of external galaxies where similar halo profile
measurements are available, with the goal of further linking the properties of
stellar halos to the accretion histories that formed them.


title: Extended nonergodic states in disordered many-body quantum systems

abstract:
  This work supports the existence of extended nonergodic states in the
intermediate region between the chaotic (thermal) and the many-body localized
phases. These states are identified through an extensive analysis of static and
dynamical properties of a finite one-dimensional system with onsite random
disorder. The long-time dynamics is particularly sensitive to changes in the
spectrum and in the structures of the eigenstates. The study of the evolution
of the survival probability, Shannon information entropy, and von Neumann
entanglement entropy enables the distinction between the chaotic and the
intermediate region.


title:
Transient Features in Charge Fractionalization, Local Equilibration and
  Non-equilibrium Bosonization

abstract:
  In quantum Hall edge states and in other one-dimensional interacting systems,
charge fractionalization can occur due to the fact that an injected charge
pulse decomposes into eigenmodes propagating at different velocities. If the
original charge pulse has some spatial width due to injection with a given
source-drain voltage, a finite time is needed until the separation between the
fractionalized pulses is larger than their width. In the formalism of
non-equilibrium bosonization, the above physics is reflected in the separation
of initially overlapping square pulses in the effective scattering phase. When
expressing the single particle Green's function as a functional determinant of
counting operators containing the scattering phase, the time evolution of
charge fractionalization is mathematically described by functional determinants
with overlapping pulses. We develop a framework for the evaluation of such
determinants, describe the system's equilibration dynamics, and compare our
theoretical results with recent experimental findings.


title:
The SLUGGS Survey: stellar masses and effective radii of early-type
  galaxies from Spitzer Space Telescope 3.6$\mu$m imaging

abstract:
  Galaxy starlight at 3.6$\mu$m is an excellent tracer of stellar mass. Here we
use the latest 3.6$\mu$m imaging from the Spitzer Space Telescope to measure
the total stellar mass and effective radii in a homogeneous way for a sample of
galaxies from the SLUGGS survey. These galaxies are representative of nearby
early-type galaxies in the stellar mass range of 10 $<$ log
M$_{\ast}$/M$_{\odot}$ $<$ 11.7, and our methodology can be applied to other
samples of early-type galaxies. We model each galaxy in 2D and estimate its
total asymptotic magnitude from a 1D curve-of-growth. Magnitudes are converted
into stellar masses using a 3.6$\mu$m mass-to-light ratio from the latest
stellar population models of R\"ock et al., assuming a Kroupa IMF. We apply a
ratio based on each galaxy's mean mass-weighted stellar age within one
effective radius (the mass-to-light ratio is insensitive to galaxy metallicity
for the generally old stellar ages and high metallicities found in massive
early-type galaxies). Our 3.6$\mu$m stellar masses agree well with masses
derived from 2.2$\mu$m data. From the 1D surface brightness profile we fit a
single Sersic law, excluding the very central regions. We measure the effective
radius, Sersic n parameter and effective surface brightness for each galaxy. We
find that galaxy sizes derived from shallow optical imaging and the 2MASS
survey tend to underestimate the true size of the largest, most massive
galaxies in our sample. We adopt the 3.6$\mu$m stellar masses and effective
radii for the SLUGGS survey galaxies.


title: Noether charge, black hole volume, and complexity

abstract:
  In this paper, we study the physical significance of the thermodynamic
volumes of AdS black holes using the Noether charge formalism of Iyer and Wald.
After applying this formalism to study the extended thermodynamics of a few
examples, we discuss how the extended thermodynamics interacts with the recent
complexity = action proposal of Brown et al. (CA-duality). We, in particular,
discover that their proposal for the late time rate of change of complexity has
a nice decomposition in terms of thermodynamic quantities reminiscent of the
Smarr relation. This decomposition strongly suggests a geometric, and via
CA-duality holographic, interpretation for the thermodynamic volume of an AdS
black hole. We go on to discuss the role of thermodynamics in complexity =
action for a number of black hole solutions, and then point out the possibility
of an alternate proposal, which we dub "complexity = volume 2.0". In this
alternate proposal, the complexity would be thought of as the spacetime volume
of the Wheeler-DeWitt patch. Finally, we provide evidence that, in certain
cases, our proposal for complexity is consistent with the Lloyd bound whereas
CA-duality is not.


title:
UKIRT microlensing surveys as a pathfinder for $WFIRST$: The detection
  of five highly extinguished low-$|b|$ events

abstract:
  Optical microlensing surveys are restricted from detecting events near the
Galactic plane and center, where the event rate is thought to be the highest,
due to the high optical extinction of these fields. In the near-infrared (NIR),
however, the lower extinction leads to a corresponding increase in event
detections and is a primary driver for the wavelength coverage of the $WFIRST$
microlensing survey. During the 2015 and 2016 bulge observing seasons we
conducted NIR microlensing surveys with UKIRT in conjunction with and in
support of the $Spitzer$ and $Kepler$ microlensing campaigns. Here we report on
five highly extinguished ($A_H=0.81-1.97$), low-Galactic latitude ($-0.98\le
b\le -0.36$) microlensing events discovered from our 2016 survey. Four of them
were monitored with an hourly cadence by optical surveys but were not reported
as discoveries, likely due to the high extinction. Our UKIRT surveys and
suggested future NIR surveys enable the first measurement of the microlensing
event rate in the NIR. This wavelength regime overlaps with the bandpass of the
filter in which the $WFIRST$ microlensing survey will conduct its
highest-cadence observations, making this event rate derivation critically
important for optimizing its yield.


title: The Linear Instability of Dilute Ultrarelativistic $e^{\pm}$ Pair Beams

abstract:
  The annihilation of TeV photons from extragalactic TeV sources and the
extragalactic background light produces ultrarelativistic $e^{\pm}$ beams,
which are subject to powerful plasma instabilities that sap their kinetic
energy. Here we study the linear phase of the plasma instabilities that these
pair beams drive. To this end, we calculate the linear growth rate of the beam
plasma and oblique instability in the electrostatic approximation in both the
reactive and kinetic regimes, assuming a Maxwell-J{\"u}ttner distribution for
the pair beam. We reproduce the well-known reactive and kinetic growth rates
for both the beam plasma and oblique mode. We demonstrate for the oblique
instability that there is a broad spectrum of unstable modes that grow at the
maximum rate for a wide range of beam temperatures and wave vector orientations
relative to the beam. We also delineate the conditions for applicability for
the reactive and kinetic regimes and find that the beam plasma mode transitions
to the reactive regime at a lower Lorentz factor than the oblique mode due to a
combination of their different scalings and the anisotropy of the velocity
dispersions. Applying these results to the ultrarelativistic $e^{\pm}$ beams
from TeV blazars, we confirm that these beams are unstable to both, the kinetic
oblique mode and the reactive beam-plasma mode. These results are important in
understanding how powerful plasma instabilities may sap the energy of the
ultrarelativistic $e^{\pm}$ beams as they propagate through intergalactic
space.


title: Interaction of Cosmic Rays with Cold Clouds in Galactic Halos

abstract:
  We investigate the effects of cosmic ray (CR) dynamics on cold, dense clouds
embedded in a hot, tenuous galactic halo. If the magnetic field does not
increase too much inside the cloud, the local reduction in Alfv\'en speed
imposes a bottleneck on CRs streaming out from the star-forming galactic disk.
The bottleneck flattens the upstream CR gradient in the hot gas, implying that
multi-phase structure could have global effects on CR driven winds. A large CR
pressure gradient can also develop on the outward-facing edge of the cloud.
This pressure gradient has two independent effects. The CRs push the cloud
upward, imparting it with momentum. On smaller scales, the CRs pressurize cold
gas in the fronts, reducing its density, consistent with the low densities of
cold gas inferred in recent COS observations of local $L_{*}$ galaxies. They
also heat the material at the cloud edge, broadening the cloud-halo interface
and causing an observable change in interface ionic abundances. Due to the much
weaker temperature dependence of cosmic ray heating relative to thermal
conductive heating, CR mediated fronts have a higher ratio of low to high ions
compared to conduction fronts, in better agreement with observations. We
investigate these effects separately using 1D simulations and analytic
techniques.


title:
HI-selected Galaxies in Hierarchical Models of Galaxy Formation and
  Evolution

abstract:
  In this work, we study the basic statistical properties of HI-selected
galaxies extracted from six different semi-analytic models, all run on the same
cosmological N-body simulation. One model includes an explicit treatment for
the partition of cold gas into atomic and molecular hydrogen. All models
considered agree nicely with the measured HI mass function in the local
Universe, with the measured scaling relations between HI and galaxy stellar
mass, and with the predicted 2-point correlation function for HI rich galaxies.
One exception is given by one model that predicts very little HI associated
with galaxies in haloes above 10^12 Msun: we argue this is due to a too
efficient radio-mode feedback for central galaxies, and to a combination of
efficient stellar feedback and instantaneous stripping of hot gas for
satellites. We demonstrate that treatment of satellite galaxies introduces
large uncertainties at low HI masses. While models assuming non instantaneous
stripping of hot gas tend to form satellite galaxies with HI masses slightly
smaller than those of centrals with the same stellar mass, instantaneous gas
stripping does not translate necessarily in lower HI masses. In fact, the
adopted stellar feedback and star formation affect the satellites too. We
analyze the relation between HI content and spin of simulated haloes: low spin
haloes tend to host HI poor galaxies while high spin haloes are populated by
galaxies in a wide range of HI mass. In our simulations, this is due to a
correlation between the initial gas disk size and the halo spin.


title:
Effective field theory approach to open heavy flavor production in
  heavy-ion collisions

abstract:
  We develop a version of Soft Collinear Effective Theory (SCET) which includes
finite quark masses, as well as Glauber gluons that describe the interaction of
collinear partons with QCD matter. In the framework of this new effective field
theory, labeled SCET$_{\mathrm{M,G}}$, we derive the massive splitting
functions in the vacuum and the QCD medium for the processes $Q\to Qg$, $Q\to
gQ$ and $g\to Q\bar Q$. The numerical effects due to finite quark masses are
sizable and our results are consistent with the traditional approach to parton
energy loss in the soft gluon emission limit. In addition, we present a new
framework for including the medium-induced full splitting functions consistent
with next-to-leading order calculations in QCD for inclusive hadron production.
Finally, we show numerical results for the suppression of $D$- and $B$-mesons
in heavy ion collisions at $\sqrt{s_{\mathrm{NN}}}=5.02$ TeV and 2.76 TeV and
compare to available data from the LHC.


title: Can dead zones create structures like a transition disk?

abstract:
  [Abridged] Regions of low ionisation where the activity of the
magneto-rotational instability is suppressed, the so-called dead zones, have
been suggested to explain gaps and asymmetries of transition disks. We
investigate the gas and dust evolution simultaneously assuming simplified
prescriptions for a dead zone and a magnetohydrodynamic (MHD) wind acting on
the disk. We explore whether the resulting gas and dust distribution can create
signatures similar to those observed in transition disks. For the dust
evolution, we included the transport, growth, and fragmentation of dust
particles. To compare with observations, we produced synthetic images in
scattered optical light and in thermal emission at mm wavelengths. In all
models with a dead zone, a bump in the gas surface density is produced that is
able to efficiently trap large particles ($\gtrsim 1$ mm) at the outer edge of
the dead zone. The gas bump reaches an amplitude of a factor of $\sim5$, which
can be enhanced by the presence of an MHD wind that removes mass from the inner
disk. While our 1D simulations suggest that such a structure can be present
only for $\sim$1 Myr, the structure may be maintained for a longer time when
more realistic 2D/3D simulations are performed. In the synthetic images,
gap-like low-emission regions are seen at scattered light and in thermal
emission at mm wavelengths, as previously predicted in the case of planet-disk
interaction. As a conclusion, main signatures of transition disks can be
reproduced by assuming a dead zone in the disk, such as gap-like structure in
scattered light and millimetre continuum emission, and a lower gas surface
density within the dead zone. Previous studies showed that the Rossby wave
instability can also develop at the edge of such dead zones, forming vortices
and also creating asymmetries.


title: New Physics in the Visible Final States of $B\to D^{(*)}\tau\nu$

abstract:
  We derive compact expressions for the helicity amplitudes of the many-body $B
\to D^{(*)}(\to DY)\tau(\to X\nu)\nu$ decays, specifically for $X = \ell \nu$
or $\pi$ and $Y = \pi$ or $\gamma$. We include contributions from all ten
possible new physics four-Fermi operators with arbitrary couplings. Our results
capture interference effects in the full phase space of the visible $\tau$ and
$D^*$ decay products which are missed in analyses that treat the $\tau$ or
$D^*$ or both as stable. The $\tau$ interference effects are sizable, formally
of order $m_\tau/m_B$ for the standard model, and may be of order unity in the
presence of new physics. Treating interference correctly is essential when
considering kinematic distributions of the $\tau$ or $D^*$ decay products, and
when including experimentally unavoidable phase space cuts. Our amplitude-level
results also allow for efficient exploration of new physics effects in the
fully differential phase space, by enabling experiments to perform such studies
on fully simulated Monte Carlo datasets via efficient event reweighing. As an
example, we explore a class of new physics interactions that can fit the
observed $R(D^{(*)})$ ratios, and show that analyses including more
differential kinematic information can provide greater discriminating power for
new physics, than single kinematic variables alone.


title:
Diagnosing galactic feedback with the line broadening in the low
  redshift Lyman-alpha forest

abstract:
  We compare the low redshift (z ~ 0.1) Lyman-alpha forest from hydrodynamical
simulations with data from the Cosmic Origin Spectrograph (COS). We find
tension between the observed number of lines with b-parameters in the range
25-45 km/s and the predictions from simulations that incorporate either
vigorous feedback from active galactic nuclei or that exclude feedback
altogether. The gas in these simulations is, respectively, either too hot to
contribute to the Lyman-alpha absorption or too cold to produce the required
line widths. Matching the observed b-parameter distribution therefore requires
feedback processes that thermally or turbulently broaden the absorption
features without collisionally (over-)ionising hydrogen. This suggests the
Lyman-alpha forest b-parameter distribution is a valulable diagnostic of
galactic feedback in the low redshift Universe. We furthermore confirm the low
redshift Lyman-alpha forest column density distribution is better reproduced by
an ultraviolet background with an HI photo-ionisation rate a factor 1.5-3
higher than predicted by Haardt & Madau (2012).


title:
Helium Reionization Simulations. II. Signatures of Quasar Activity on
  the IGM

abstract:
  We have run a new suite of simulations that solve hydrodynamics and radiative
transfer simultaneously to study helium II reionization. Our suite of
simulations employs various models for populating quasars inside of dark matter
halos, which affect the He II reionization history. In particular, we are able
to explore the impact that differences in the timing and duration of
reionization have on observables. We examine the thermal signature that
reionization leaves on the IGM, and measure the temperature-density relation.
As previous studies have shown, we confirm that the photoheating feedback from
helium II reionization raises the temperature of the IGM by several thousand
kelvin. To compare against observations, we generate synthetic Ly$\alpha$
forest sightlines on-the-fly and match the observed effective optical depth
$\tau_{\mathrm{eff}}(z)$ of hydrogen to recent observations. We show that when
the simulations have been normalized to have the same values of
$\tau_\mathrm{eff}$, the effect that helium II reionization has on observations
of the hydrogen Ly$\alpha$ forest is minimal. Specifically, the flux PDF and
the one-dimensional power spectrum are sensitive to the thermal state of the
IGM, but do not show direct evidence for the ionization state of helium. We
show that the peak temperature of the IGM typically corresponds to the time of
90%-95% helium ionization by volume, and is a relatively robust indicator of
the timing of reionization. Future observations of helium reionization from the
hydrogen Ly$\alpha$ forest should thus focus on measuring the temperature of
the IGM, especially at mean density. Detecting the peak in the IGM temperature
would provide valuable information about the timing of the end of helium II
reionization.


title: Learning phase transitions by confusion

abstract:
  Classifying phases of matter is a central problem in physics. For quantum
mechanical systems, this task can be daunting owing to the exponentially large
Hilbert space. Thanks to the available computing power and access to ever
larger data sets, classification problems are now routinely solved using
machine learning techniques. Here, we propose to use a neural network based
approach to find phase transitions depending on the performance of the neural
network after training it with deliberately incorrectly labelled data. We
demonstrate the success of this method on the topological phase transition in
the Kitaev chain, the thermal phase transition in the classical Ising model,
and the many-body-localization transition in a disordered quantum spin chain.
Our method does not depend on order parameters, knowledge of the topological
content of the phases, or any other specifics of the transition at hand. It
therefore paves the way to a generic tool to identify unexplored phase
transitions.


title:
An analytical formalism accounting for clouds and other "surfaces" for
  exoplanet transmission spectroscopy

abstract:
  Although the formalism of Lecavelier des Etangs et al. (2008) is extremely
useful to understand what shapes transmission spectra of exoplanets, it does
not include the effects of a sharp change in flux with altitude generally
associated with surfaces and optically thick clouds. Recent advances in
understanding the effects of refraction in exoplanet transmission spectra have,
however, demonstrated that even clear thick atmospheres have such a sharp
change in flux due to a refractive boundary. We derive a more widely applicable
analytical formalism by including first-order effects from all these "surfaces"
to compute an exoplanet's effective radius, effective atmospheric thickness,
and spectral modulation for an atmosphere with a constant scale height. We show
that the effective radius cannot be located below these "surfaces" and that our
formalism matches Lecavelier des Etangs et al. (2008)'s in the case of a clear
atmosphere. Our formalism explains why clouds and refraction reduce the
contrast of spectral features, and why refraction decreases the Rayleigh
scattering slope as wavelength increases, but also shows that these are common
effects of all "surfaces". We introduce the concept of a "surface" cross
section, the minimum mean cross section that can be observed, as an index to
characterize the location of "surfaces" and provide a simple method to estimate
their effects on the spectral modulation of homogeneous atmospheres. We finally
devise a numerical recipe that extends our formalism to atmospheres with a
non-constant scale height and arbitrary sources of opacity, a potentially
necessary step to interpret observations.


title:
Artificial Neural Network Based Power System Stabilizer on a Single
  Machine Infinite Bus Modelled in Digsilent Powerfactory and MATLAB

abstract:
  In this paper the use of artificial neural network in power system stability
is studied. A predictive controller based on two neural networks is designed
and tested on a single machine infinite bus system which is used to replace
conventional power system stabilizers. They have been used for decades in power
system to dampen small amplitude low frequency oscillation in power systems.
The increases in size and complexity of power systems have cast a shadow on
efficiency of conventional method. New control strategies have been proposed in
many researches. Artificial Neural Networks have been studied in many
publications but lack of assurance of their functionality has hindered the
practical usage of them in utilities. The proposed control structure is
modelled using a novel data exchange established between MATLAB and


title: Looking inside three-dimensional (3D) silicon photonic band gap crystals

abstract:
  We have performed an x-ray holotomography study of a three-dimensional (3D)
photonic band gap crystal. The crystals was made from silicon by
CMOS-compatible methods. We manage to obtain the 3D material density throughout
the fabricated crystal. We observe that the structural design is for most
aspects well-realized by the fabricated nanostructure. One peculiar feature is
a slight shear-distortion of the cubic crystal structure. We conclude that 3D
X-ray tomography has great potential to solve many future questions on optical
metamaterials.


title: Chiral Closed strings: Four massless states scattering amplitude

abstract:
  We compute the scattering amplitudes of four massless states for chiral
(closed) bosonic and type II superstrings using the Kawai-Lewellen-Tye ($KLT$)
factorization method. The amplitude in the chiral bosonic case is identical to
a field theory amplitude corresponding to the spin-$2$ tachyon, massless
gravitational sector and massive spin-2 tardyon states of the spectrum. Chiral
type II superstrings amplitude only possess poles associated with the massless
gravitational sector. We briefly discuss the extension of the calculation to
heterotic superstrings.


title:
Biorthogonal projected energies of a Gutzwiller similarity transformed
  Hamiltonian

abstract:
  We present a method incorporating biorthogonal orbital-optimization, symmetry
projection, and double-occupancy screening with a non-unitary similarity
transformation generated by the Gutzwiller factor $
n_{i\uparrow}n_{i\downarrow}$, and apply it to the Hubbard model. Energies are
calculated with mean-field computational scaling with high-quality results
comparable to coupled cluster singles and doubles. This builds on previous work
performing similarity transformations with more general, two-body Jastrow-style
correlators. The theory is tested on two-dimensional lattices ranging from
small systems into the thermodynamic limit and is compared to available
reference data.


title: Frequency estimate for multicomponent crystalline compounds

abstract:
  Among crystal structures of N-component metal alloys, far fewer examples are
known with N>=4 than with N=2 or 3, in apparent contradiction to the
exponentially growing number of possible combinations of elements. Two effects
contribute to this shortfall. Since the N-component composition space resides
within a d-dimensional simplex with d=N-1, the vanishing volume in high
dimensions reduces the distinct N-component compositions. Additionally, the
increasing surface area makes it more probable that stable structures reside on
the surface of the simplex (containing fewer than N components) as opposed to
its interior. Despite their rarity, we propose that the actual number of N=4-
and 5-component alloys greatly exceeds the number that are currently known.
Specific estimates are developed through application of the empirical Miedema
enthalpy model.


title: Places: An Image Database for Deep Scene Understanding

abstract:
  The rise of multi-million-item dataset initiatives has enabled data-hungry
machine learning algorithms to reach near-human semantic classification at
tasks such as object and scene recognition. Here we describe the Places
Database, a repository of 10 million scene photographs, labeled with scene
semantic categories and attributes, comprising a quasi-exhaustive list of the
types of environments encountered in the world. Using state of the art
Convolutional Neural Networks, we provide impressive baseline performances at
scene classification. With its high-coverage and high-diversity of exemplars,
the Places Database offers an ecosystem to guide future progress on currently
intractable visual recognition problems.


title:
Constant Approximation Algorithm for Non-Uniform Capacitated Multi-Item
  Lot-Sizing via Strong Covering Inequalities

abstract:
  We study the non-uniform capacitated multi-item lot-sizing (\lotsizing)
problem. In this problem, there is a set of demands over a planning horizon of
$T$ time periods and all demands must be satisfied on time. We can place an
order at the beginning of each period $s$, incurring an ordering cost $K_s$.
The total quantity of all products ordered at time $s$ can not exceed a given
capacity $C_s$. On the other hand, carrying inventory from time to time incurs
inventory holding cost. The goal of the problem is to find a feasible solution
that minimizes the sum of ordering and holding costs.
  Levi et al.\ (Levi, Lodi and Sviridenko, Mathmatics of Operations Research
33(2), 2008) gave a 2-approximation for the problem when the capacities $C_s$
are the same. In this paper, we extend their result to the case of non-uniform
capacities. That is, we give a constant approximation algorithm for the
capacitated multi-item lot-sizing problem with general capacities.
  The constant approximation is achieved by adding an exponentially large set
of new covering inequalities to the natural facility-location type linear
programming relaxation for the problem. Along the way of our algorithm, we
reduce the \lotsizing problem to two generalizations of the classic knapsack
covering problem. We give LP-based constant approximation algorithms for both
generalizations, via the iterative rounding technique.


title:
The SINFONI survey of powerful radio galaxies at z~2: Jet-driven AGN
  feedback during the Quasar Era

abstract:
  We present VLT/SINFONI imaging spectroscopy of the warm ionized gas in 33
powerful radio galaxies at redshifts z>~2, which are excellent sites to study
the interplay of rapidly accreting active galactic nuclei and the interstellar
medium of the host galaxy in the very late formation stages of massive
galaxies. Our targets span two orders of magnitude in radio size (2-400 kpc)
and kinetic jet energy (a few 10^46 to almost 10^48 erg s^-1). All sources have
complex gas kinematics with broad line widths up to ~1300 km s^-1. About half
have bipolar velocity fields with offsets up to 1500 km s^-1 and are consistent
with global back-to-back outflows. The others have complex velocity
distributions, often with multiple abrupt velocity jumps far from the nucleus
of the galaxy, and are not associated with a major merger in any obvious way.
We present several empirical constraints that show why gas kinematics and radio
jets seem to be physically related. The gas kinetic energy from large scale
bulk and local outflow or turbulent motion corresponds to a few 10^-3 to 10^-2
of the kinetic energy of the jet. In galaxies with jet power >~10^47 erg s^-1,
the bulk kinetic energy dominates the total energy budget of the gas,
suggesting that the outflows encompasses the global interstellar medium,
perhaps facilitated by the strong gas turbulence. We compare with recent
hydrodynamic simulations, and discuss the potential consequences for the
subsequent evolution of massive high-z galaxies. The gas-phase metallicities in
our galaxies are lower than in most low-z AGN, but nonetheless solar or even
super-solar, suggesting that the ISM in these galaxies is very similar to the
gas from which massive low-redshift galaxies formed most of their gas. This
further highlights that we are seeing these galaxies near the end of their
active formation phase.


title:
On the inverse and conventional magnetocaloric effects in MnRhAs single
  crystals

abstract:
  We report on the magnetic and magnetocaloric properties of a MnRhAs single
crystal. The ternary arsenide exhibits a rather complex magnetic behaviour. A
first order metamagnetic type transition from antiferromagnetic (AFI) to
ferromagnetic (F) states takes place at Tt ~ 158 K, and a second order
transition from ferromagnetic (F) to antiferromagnetic (AFII) states occurs at
TC ~196 K, the paramagnetic state occurring at T > TN = 238 K. Magnetic entropy
changes were calculated using, Maxwell relation and Clausius-Clapeyron
equation. Both approaches are compared and discussed. The AFI-F transition in
MnRhAs gives rise to an interestingly high level of negative magnetocaloric
effect. Under a field change 0-1 T, the maximum magnetic entropy variation is
about 3 J/kg K. For sufficiently high enough magnetic fields, the
magnetocaloric working temperature range below 158 K can be covered. The F-AFII
transition is accompanied by a relatively modest MCE (-2.3 J/kg K for 5 T at TC
= 196 K), but it improves the working temperature span as well as the
magnetocaloric properties. A minimum estimated refrigerant capacity of about
900 J/kg can be provided by a MnRhAs single crystal compound


title:
Non-inner automorphisms of order p in finite normally constrained
  p-groups

abstract:
  In this paper we study the existence of at least one non-inner automorphism
of order p in a finite normally constrained p-group when p is an odd prime.


title: After Sandy Hook Elementary: A Year in the Gun Control Debate on Twitter

abstract:
  The mass shooting at Sandy Hook elementary school on December 14, 2012
catalyzed a year of active debate and legislation on gun control in the United
States. Social media hosted an active public discussion where people expressed
their support and opposition to a variety of issues surrounding gun
legislation. In this paper, we show how a content-based analysis of Twitter
data can provide insights and understanding into this debate. We estimate the
relative support and opposition to gun control measures, along with a topic
analysis of each camp by analyzing over 70 million gun-related tweets from
2013. We focus on spikes in conversation surrounding major events related to
guns throughout the year. Our general approach can be applied to other
important public health and political issues to analyze the prevalence and
nature of public opinion.


title: Photon echoes for a system of large negative spin and few photons

abstract:
  Persistent photon echoes are seen for the case of a large number of two-level
molecules (TLMs) prepared initially in the all-down state (large negative spin)
interacting with a photon distribution with a small mean photon number in a
lossless cavity. This case is interesting since 1) it has not been
significantly addressed in the past; 2) the characteristic times associated
with revival are not what is seen for the more frequently addressed problem of
a few TLMs interacting with a photon distribution with a large mean photon
number; 3) long after the echoes die out, they re-emerge completely at a much
later time; and 4) the existence of echoes is not predicated on the initial
photon distribution being the coherent state or Glauber distribution. Entropy,
entanglement, and the Q function are considered. It is found that
disentanglement only occurs at the revival times as evidenced by the entropy
going to 0 and the Q function returning to the value seen at time=0. Comparison
to the more normally seen results for large mean photon number and small
numbers of TLMs are discussed. Finally this paper acts as a general reference
for future refereed publications.


title: Back to mechanisms of superconductivity in low-doped strontium titanate

abstract:
  We have analyzed two mechanisms proposed recently for superconductivity in
doped SrTiO3 - the plasmon-mediated pairing and the potential of an
instantaneous attraction between two electrons that owes its origin to the
exchange by high-frequency optical phonons. The first approach seems to be
self-consistent, but in a limited range of the dielectric constant. As to the
direct instantaneous interaction between two electrons,it was hypothesized as
due to the exchange by the band LO phonons. The latter supposition was
incorrect. In the current paper, it shows that the contributions into the
pairing matrix element possessing the structure of a net attraction come about
only as the result of disorder. Indeed, the experiment revealed the mobility
edge in doped SrTiO3. Doped electrons occupying states with the energy below
the mobility edge are localized on dopants thereby become strongly coupled with
the lattice vibrations. The emergence of the localized phonon modes attached to
defect is one of the results of such electron-lattice coupling. For two
electrons in the conduction band the virtual exchange by the quantum of such
local mode manifests itself as the effective attraction. The total contribution
into the pairing matrix element from these processes, increasing with
concentration can overwhelm the Coulomb repulsion screened by the band LO
phonons. That is, the role previously ascribed to the band LO phonons actually
belongs to the localized phonons.


title: Bisecting binomial coefficients

abstract:
  In this paper, we deal with the problem of bisecting binomial coefficients.
We find many (previously unknown) infinite classes of integers which admit
nontrivial bisections, and a class with only trivial bisections. As a byproduct
of this last construction, we show conjectures Q2 and Q4 of Cusick and Li. We
next find several bounds for the number of nontrivial bisections and further
compute (using a supercomputer) the exact number of such bisections for n <=
51.


title: Stretching of viscoelastic drops by steady sliding

abstract:
  The sliding of non-Newtonian drops down planar surfaces results in a complex,
entangled balance between interfacial forces and non linear viscous
dissipation, which has been scarcely inspected. In particular, a detailed
understanding of the role played by the polymer flexibility and the resulting
elasticity of the polymer solution is still lacking. To this aim, we have
considered polyacrylamide (PAA) solutions of different molecular weights,
suspended either in water or glycerol/water mixtures. In contrast to drops with
stiff polymers, drops with flexible polymers exhibit a remarkable elongation in
steady sliding. This difference is most likely attributed to different viscous
bending as a consequence of different shear thinning. Moreover, an "optimal
elasticity" of the polymer seems to be required for this drop elongation to be
visible. We have complemented experimental results with numerical simulations
of a viscoelastic FENE-P drop. This has been a decisive step to unravel how a
change of the elastic parameters (e.g. polymer relaxation time, maximum
extensibility) affects the dimensionless sliding velocity.


title:
Towards an Autonomous System Monitor for Mitigating Correlation Attacks
  in the Tor Network

abstract:
  After carefully considering the scalability problem in Tor and exhaustively
evaluating related works on AS-level adversaries, the author proposes
ASmoniTor, which is an autonomous system monitor for mitigating correlation
attacks in the Tor network. In contrast to prior works, which often released
offline packets, including the source code of a modified Tor client and a
snapshot of the Internet topology, ASmoniTor is an online system that assists
end users with mitigating the threat of AS-level adversaries in a near
real-time fashion. For Tor clients proposed in previous works, users need to
compile the source code on their machine and continually update the snapshot of
the Internet topology in order to obtain accurate AS-path inferences. On the
contrary, ASmoniTor is an online platform that can be utilized easily by not
only technical users, but also by users without a technical background, because
they only need to access it via Tor and input two parameters to execute an
AS-aware path selection algorithm. With ASmoniTor, the author makes three key
technical contributions to the research against AS-level adversaries in the Tor
network. First, ASmoniTor does not require the users to initiate complicated
source code compilations. Second, it helps to reduce errors in AS-path
inferences by letting users input a set of suspected ASes obtained directly
from their own traceroute measurements. Third, the Internet topology database
at the back-end of ASmoniTor is periodically updated to assure near real-time
AS-path inferences between Tor exit nodes and the most likely visited websites.
Finally, in addition to its convenience, ASmoniTor gives users full control
over the information they want to input, thus preserving their privacy.


title: A Hybrid Sampling Scheme for Triangle Counting

abstract:
  We study the problem of estimating the number of triangles in a graph stream.
No streaming algorithm can get sublinear space on all graphs, so methods in
this area bound the space in terms of parameters of the input graph such as the
maximum number of triangles sharing a single edge. We give a sampling algorithm
that is additionally parameterized by the maximum number of triangles sharing a
single vertex. Our bound matches the best known turnstile results in all
graphs, and gets better performance on simple graphs like $G(n, p)$ or a set of
independent triangles.
  We complement the upper bound with a lower bound showing that no sampling
algorithm can do better on those graphs by more than a log factor. In
particular, any insertion stream algorithm must use $\sqrt{T}$ space when all
the triangles share a common vertex, and any sampling algorithm must take
$T^\frac{1}{3}$ samples when all the triangles are independent. We add another
lower bound, also matching our algorithm's performance, which applies to all
graph classes. This lower bound covers "triangle-dependent" sampling
algorithms, a subclass that includes our algorithm and all previous sampling
algorithms for the problem.
  Finally, we show how to generalize our algorithm to count arbitrary subgraphs
of constant size.


title:
Stochastic Games for Smart Grid Energy Management with Prospect
  Prosumers

abstract:
  In this paper, the problem of smart grid energy management under stochastic
dynamics is investigated. In the considered model, at the demand side, it is
assumed that customers can act as prosumers who own renewable energy sources
and can both produce and consume energy. Due to the coupling between the
prosumers' decisions and the stochastic nature of renewable energy, the
interaction among prosumers is formulated as a stochastic game, in which each
prosumer seeks to maximize its payoff, in terms of revenues, by controlling its
energy consumption and demand. In particular, the subjective behavior of
prosumers is explicitly reflected into their payoff functions using prospect
theory, a powerful framework that allows modeling real-life human choices. For
this prospect-based stochastic game, it is shown that there always exists a
stationary Nash equilibrium where the prosumers' trading policies in the
equilibrium are independent of the time and their histories of the play.
Moreover, a novel distributed algorithm with no information sharing among
prosumers is proposed and shown to converge to an $\epsilon$-Nash equilibrium.
On the other hand, at the supply side, the interaction between the utility
company and the prosumers is formulated as an online optimization problem in
which the utility company's goal is to learn its optimal energy allocation
rules. For this case, it is shown that such an optimization problem admits a
no-regret algorithm meaning that regardless of the actual outcome of the game
among the prosumers, the utility company can follow a strategy that mitigates
its allocation costs as if it knew the entire demand market a priori.
Simulation results show the convergence of the proposed algorithms to their
predicted outcomes and present new insights resulting from prospect theory that
contribute toward more efficient energy management in the smart grids.


title:
Searching For Fossil Evidence of AGN Feedback in WISE-Selected Stripe-82
  Galaxies By Measuring the Thermal Sunyaev-Zel'dovich Effect With the Atacama
  Cosmology Telescope

abstract:
  We directly measure the thermal energy of the gas surrounding galaxies
through the thermal Sunyaev-Zel'dovich (tSZ) effect. We perform a stacking
analysis of microwave background images from the Atacama Cosmology Telescope,
around 1179 massive quiescent elliptical galaxies at 0.5 <= z <= 1.0 ('low-z')
and 3274 galaxies at 1.0 <= z <= 1.5 ('high-z'), selected using data from the
Wide-Field Infrared Survey Explorer All-Sky Survey and the Sloan Digital Sky
Survey (SDSS) within the SDSS Stripe-82 field. The gas surrounding these
galaxies is expected to contain energy from past episodes of active galactic
nucleus (AGN) feedback, and after using modeling to subtract undetected
contaminants, we detect a tSZ signal at a significance of 0.9-sigma for our
low-z galaxies and 1.8-sigma for our high-z galaxies. We then include data from
the high-frequency Planck bands for a subset of 227 low-z galaxies and 529
high-z galaxies and find low-z and high-z tSZ detections of 1.0-sigma and
1.5-sigma, respectively. These results indicate an average thermal heating
around these galaxies of 5.6(+5.9/-5.6) x 10^60 erg for our low-z galaxies and
7.0(+4.7/-4.4) x 10^60 erg for our high-z galaxies. Based on simple heating
models, these results are consistent with gravitational heating without
additional heating due to AGN feedback.


title:
Signature of the N=126 shell closure in dwell times of alpha-particle
  tunneling

abstract:
  Characteristic quantities such as the penetration and preformation
probabilities, assault frequency and tunneling times in the tunneling
description of alpha decay of heavy nuclei are explored to reveal their
sensitivity to neutron numbers in the vicinity of the magic neutron number $N$
= 126. Using realistic nuclear potentials, the sensitivity of these quantities
to the parameters of the theoretical approach is also tested. An investigation
of the region from $N=116$ to $N=132$ in Po nuclei reveals that the tunneling
$\alpha$ particle spends the least amount of time with an $N=126$ magic
daughter nucleus. The shell closure at $N=126$ seems to affect the behaviour of
the dwell times of the tunneling alpha particles and this occurs through the
influence of the $Q$-values involved.


title:
Kernel/Metric Correspondence of Dissipative Systems in Information
  Theory

abstract:
  We study the kernel/metric correspondence pointed out in our previous work in
a dissipative system which is accompanying fractional Brownian motion. We also
give some comments on information causality.


title: Addendum to " Sum rules via large deviations "

abstract:
  In these notes we fill a gap in a proof in Section 4 of Gamboa, Nagel,
Rouault [Sum rules via large deviations, J. Funct. Anal. 270 (2016), 509-559].
We prove a general theorem which combines a LDP with a convex rate function and
a LDP with a non-convex one. This result will be used to prove LDPs for
spectral matrix measures and for spectral measures on the unit circle.


title: An efficient high-probability algorithm for Linear Bandits

abstract:
  For the linear bandit problem, we extend the analysis of algorithm CombEXP
from [R. Combes, M. S. Talebi Mazraeh Shahi, A. Proutiere, and M. Lelarge.
Combinatorial bandits revisited. In C. Cortes, N. D. Lawrence, D. D. Lee, M.
Sugiyama, and R. Garnett, editors, Advances in Neural Information Processing
Systems 28, pages 2116--2124. Curran Associates, Inc., 2015. URL
http://papers.nips.cc/paper/5831-combinatorial-bandits-revisited.pdf] to the
high-probability case against adaptive adversaries, allowing actions to come
from an arbitrary polytope. We prove a high-probability regret of
\(O(T^{2/3})\) for time horizon \(T\). While this bound is weaker than the
optimal \(O(\sqrt{T})\) bound achieved by GeometricHedge in [P. L. Bartlett, V.
Dani, T. Hayes, S. Kakade, A. Rakhlin, and A. Tewari. High-probability regret
bounds for bandit online linear optimization. In 21th Annual Conference on
Learning Theory (COLT 2008), July 2008.
http://eprints.qut.edu.au/45706/1/30-Bartlett.pdf], CombEXP is computationally
efficient, requiring only an efficient linear optimization oracle over the
convex hull of the actions.


title: Quillen equivalences for stable categories

abstract:
  For an abelian category $\mathcal{A}$ we investigate when the stable
categories $\underline{\mathrm{GPro}}\mathrm{j}(\mathcal{A})$ and
$\underline{\mathrm{GIn}}\mathrm{j}(\mathcal{A})$ are triangulated equivalent.
To this end, we realize these stable categories as homotopy categories of
certain (non-trivial) model categories and give conditions on $\mathcal{A}$
that ensure the existence of a Quillen equivalence between the model categories
in question. We also study when such a Quillen equivalence transfers from
$\mathcal{A}$ to categories naturally associated to $\mathcal{A}$, such as
$\mathrm{Ch}(\mathcal{A})$, the category of chain complexes in $\mathcal{A}$,
or $\mathrm{Rep}(Q,\mathcal{A})$, the category of $\mathcal{A}$-valued
representations of a quiver $Q$.


title:
1+1 Large $N_c$ QCD and its Holographic Dual -Soliton Picture of Baryons
  in Single-Flavor World

abstract:
  We study baryons in holographic QCD corresponding to 1+1 dimensional
single-flavor ($N_f$=1) QCD for the first time. We formulate 1+1 QCD using an
$S^1$-compactified D2/D8/$\overline{\rm D8}$ branes in the superstring theory,
and describe the baryon as a topological configuration in 1+1 $N_f$=1 QCD,
corresponding to $\Pi_1({\rm U(1)})={\bf Z}$. Unlike 1+3 QCD with $N_f \ge 2$,
however, we find that the low-dimensional baryonic soliton is generally
unstable against a scale transformation/variation and swells infinitely in 1+1
$N_f$=1 QCD at the leading of large $N_c$. We thus point out a serious
difficulty on the soliton picture of baryons in large $N_c$ in the
single-flavor world in both 1+1 and 1+3 QCD. We also compare the
low-dimensional holographic baryon with the Abrikosov vortex, i.e., a stable
topological configuration in Type-II superconductors.


title: Equivariant Gr\"obner bases

abstract:
  Algorithmic computation in polynomial rings is a classical topic in
mathematics. However, little attention has been given to the case of rings with
an infinite number of variables until recently when theoretical efforts have
made possible the development of effective routines. Ability to compute relies
on finite generation up to symmetry for ideals invariant under a large group or
monoid action, such as the permutations of the natural numbers. We summarize
the current state of theory and applications for equivariant Gr\"obner bases,
develop several algorithms to compute them, showcase our software
implementation, and close with several open problems and computational
challenges.


title:
Signal yields, energy resolution, and recombination fluctuations in
  liquid xenon

abstract:
  This work presents an analysis of monoenergetic electronic recoil peaks in
the dark-matter-search and calibration data from the first underground science
run of the Large Underground Xenon (LUX) detector. Liquid xenon charge and
light yields for electronic recoil energies between 5.2 and 661.7 keV are
measured, as well as the energy resolution for the LUX detector at those same
energies. Additionally, there is an interpretation of existing measurements and
descriptions of electron-ion recombination fluctuations in liquid xenon as
limiting cases of a more general liquid xenon re- combination fluctuation
model. Measurements of the standard deviation of these fluctuations at
monoenergetic electronic recoil peaks exhibit a linear dependence on the number
of ions for energy deposits up to 661.7 keV, consistent with previous LUX
measurements between 2-16 keV with $^3$H. We highlight similarities in liquid
xenon recombination for electronic and nuclear recoils with a comparison of
recombination fluctuations measured with low-energy calibration data.


title: A property of the Birkhoff polytope

abstract:
  The Birkhoff polytope $B_n$ is the convex hull of all $n\times n$ permutation
matrices in $\mathbb{R}^{n\times n}$. We compute the combinatorial symmetry
group of the Birkhoff polytope.
  A representation polytope is the convex hull of some finite matrix group
$G\leq \operatorname{GL}(d,\mathbb{R})$. We show that the group of permutation
matrices is essentially the only finite matrix group which yields a
representation polytope with the same face lattice as the Birkhoff polytope.


title: On 2-dimensional Kaehler metrics with one holomorphic isometry

abstract:
  We show how to write any Kaehler metric of complex dimension 2 admitting a
holomorphic isometry as a simple 1-real-function deformation of a
Gibbons-Hawking metric. Hyper-Kaehler metrics with a tri-holomorphic isometry
(Gibbons-Hawking metrics) or with a mono-holomorphic isometry are recovered for
particular values of the additional function. The new general metric can be
used as an Ansatz in several interesting physical problems.


title: Almost Engel compact groups

abstract:
  We say that a group $G$ is almost Engel if for every $g\in G$ there is a
finite set ${\mathscr E}(g)$ such that for every $x\in G$ all sufficiently long
commutators $[...[[x,g],g],\dots ,g]$ belong to ${\mathscr E}(g)$, that is, for
every $x\in G$ there is a positive integer $n(x,g)$ such that
$[...[[x,g],g],\dots ,g]\in {\mathscr E}(g)$ if $g$ is repeated at least
$n(x,g)$ times. (Thus, Engel groups are precisely the almost Engel groups for
which we can choose ${\mathscr E}(g)=\{ 1\}$ for all $g\in G$.)
  We prove that if a compact (Hausdorff) group $G$ is almost Engel, then $G$
has a finite normal subgroup $N$ such that $G/N$ is locally nilpotent. If in
addition there is a uniform bound $|{\mathscr E}(g)|\leq m$ for the orders of
the corresponding sets, then the subgroup $N$ can be chosen of order bounded in
terms of $m$. The proofs use the Wilson--Zelmanov theorem saying that Engel
profinite groups are locally nilpotent.


title: On Shapley value for measuring importance of dependent inputs

abstract:
  This paper makes the case for using Shapley value to quantify the importance
of random input variables to a function. Alternatives based on the ANOVA
decomposition can run into conceptual and computational problems when the input
variables are dependent. Our main goal here is to show that Shapley value
removes the conceptual problems. We do this with some simple examples where
Shapley value leads to intuitively reasonable nearly closed form values.


title: Investigation of the light four-quark states with exotic $J^{PC}=0^{--}$

abstract:
  We study the exotic $J^{PC}=0^{--}$ four-quark states in Laplace sum rules
(LSR) and finite energy sum rules (FESR). We use the vector tetraquark-like
currents as interpolating currents in the correlator, from which the $1^{+-}$
states are also studied. In the mass extraction, we use the standard stability
criterion with respect to the Borel parameters and the QCD continuum thresholds
and consider the effect of the violation of factorization in estimating the
high dimensional condensates as a source of uncertainties. The obtained mass
prediction $1.66\pm0.14$ GeV is much lower than the previous sum rule
predictions obtained using the scalar currents. Our result favours the
four-quark interpretation of the possible $\rho\pi$ dominance in the $D^0$
decay. We also discuss the possible decay patterns of these exotic four-quark
states.


title: Protostellar Outflows in L1340

abstract:
  We have searched the L1340 A, B, and C clouds for shocks from protostellar
outflows using the H$_2$ 2.122 $\mu$m near-IR line as a shock tracer.
Substantial outflow activity has been found in each of the three regions of the
cloud (L1340 A, L1340 B, & L1340 C). We find 42 distinct shock complexes (16 in
L1340 A, 11 in L1340 B, and 15 in L1340 C). We were able to link 17 of those
shock complexes in to 12 distinct outflows and identify candidate source stars
for each. We examine the properties (A$_{V}$, T$_{bol}$, and L$_{bol}$) of the
source protostars and compare that to the properties of the general population
of Class 0/I and flat SED protostars and find that there is an indication,
albeit at low statistical significance, that the outflow driving protostars are
drawn from a population with lower A$_{V}$, higher L$_{bol}$, and lower
T$_{bol}$ than the general population of protostars.


title:
Analytic Solution of the Electromagnetic Eigenvalues Problem in a
  Cylindrical Resonator

abstract:
  Resonant accelerating cavities are key components in modern particles
accelerating facilities. These take advantage of electromagnetic fields
resonating at microwave frequencies to accelerate charged particles. Particles
gain finite energy at each passage through a cavity if in phase with the
resonating field, reaching energies even of the order of $TeV$ when a cascade
of accelerating resonators are present. In order to understand how a resonant
accelerating cavity transfers energy to charged particles, it is important to
determine how the electromagnetic modes are exited into such resonators. In
this paper we present a complete analytical calculation of the resonating
fields for a simple cylindrical-shaped cavity.


title:
Computational Tradeoffs in Biological Neural Networks: Self-Stabilizing
  Winner-Take-All Networks

abstract:
  We initiate a line of investigation into biological neural networks from an
algorithmic perspective. We develop a simplified but biologically plausible
model for distributed computation in stochastic spiking neural networks and
study tradeoffs between computation time and network complexity in this model.
Our aim is to abstract real neural networks in a way that, while not capturing
all interesting features, preserves high-level behavior and allows us to make
biologically relevant conclusions.
  In this paper, we focus on the important `winner-take-all' (WTA) problem,
which is analogous to a neural leader election unit: a network consisting of
$n$ input neurons and $n$ corresponding output neurons must converge to a state
in which a single output corresponding to a firing input (the `winner') fires,
while all other outputs remain silent. Neural circuits for WTA rely on
inhibitory neurons, which suppress the activity of competing outputs and drive
the network towards a converged state with a single firing winner. We attempt
to understand how the number of inhibitors used affects network convergence
time.
  We show that it is possible to significantly outperform naive WTA
constructions through a more refined use of inhibition, solving the problem in
$O(\theta)$ rounds in expectation with just $O(\log^{1/\theta} n)$ inhibitors
for any $\theta$. An alternative construction gives convergence in
$O(\log^{1/\theta} n)$ rounds with $O(\theta)$ inhibitors. We compliment these
upper bounds with our main technical contribution, a nearly matching lower
bound for networks using $\ge \log\log n$ inhibitors. Our lower bound uses
familiar indistinguishability and locality arguments from distributed computing
theory. It lets us derive a number of interesting conclusions about the
structure of any network solving WTA with good probability, and the use of
randomness and inhibition within such a network.


title: Influence of Pok\'emon Go on Physical Activity: Study and Implications

abstract:
  Physical activity helps people maintain a healthy weight and reduces the risk
for several chronic diseases. Although this knowledge is widely recognized,
adults and children in many countries around the world do not get recommended
amounts of physical activity. While many interventions are found to be
ineffective at increasing physical activity or reaching inactive populations,
there have been anecdotal reports of increased physical activity due to novel
mobile games that embed game play in the physical world. The most recent and
salient example of such a game is Pok\'emon Go, which has reportedly reached
tens of millions of users in the US and worldwide.
  We study the effect of Pok\'emon Go on physical activity through a
combination of signals from large-scale corpora of wearable sensor data and
search engine logs for 32 thousand users over a period of three months.
Pok\'emon Go players are identified through search engine queries and activity
is measured through accelerometry. We find that Pok\'emon Go leads to
significant increases in physical activity over a period of 30 days, with
particularly engaged users (i.e., those making multiple search queries for
details about game usage) increasing their activity by 1473 steps a day on
average, a more than 25% increase compared to their prior activity level
($p<10^{-15}$). In the short time span of the study, we estimate that Pok\'emon
Go has added a total of 144 billion steps to US physical activity. Furthermore,
Pok\'emon Go has been able to increase physical activity across men and women
of all ages, weight status, and prior activity levels showing this form of game
leads to increases in physical activity with significant implications for
public health. We find that Pok\'emon Go is able to reach low activity
populations while all four leading mobile health apps studied in this work
largely draw from an already very active population.


title: Electron quantum optics as quantum signal processing

abstract:
  The recent developments of electron quantum optics in quantum Hall edge
channels have given us new ways to probe the behavior of electrons in quantum
conductors. It has brought new quantities called electronic coherences under
the spotlight. In this paper, we explore the relations between electron quantum
optics and signal processing through a global review of the various methods for
accessing single- and two-electron coherences in electron quantum optics. We
interpret electron quantum optics interference experiments as analog signal
processing converting quantum signals into experimentally observable quantities
such as current averages and correlations.
  This point of view also gives us a procedure to obtain quantum information
quantities from electron quantum optics coherences. We illustrate these ideas
by discussing two mode entanglement in electron quantum optics. We also sketch
how signal processing ideas may open new perspectives for representing
electronic coherences in quantum conductors and understand the properties of
the underlying many-body electronic state.


title: How to Measure the Quantum Measure

abstract:
  The histories-based framework of Quantum Measure Theory assigns a generalized
probability or measure $\mu(E)$ to every (suitably regular) set $E$ of
histories. Even though $\mu(E)$ cannot in general be interpreted as the
expectation value of a selfadjoint operator (or POVM), we describe an
arrangement which makes it possible to determine $\mu(E)$ experimentally for
any desired $E$. Taking, for simplicity, the system in question to be a
particle passing through a series of Stern-Gerlach devices or beam-splitters,
we show how to couple a set of ancillas to it, and then to perform on them a
suitable unitary transformation followed by a final measurement, such that the
probability of a final outcome of "yes" is related to $\mu(E)$ by a known
factor of proportionality. Finally, we discuss in what sense a positive outcome
of the final measurement should count as a minimally disturbing verification
that the microscopic event $E$ actually happened.


title: Branching diffusion with interactions

abstract:
  A $d$-dimensional branching diffusion, $Z$, is investigated, where the linear
attraction or repulsion between particles is competing with an
Ornstein-Uhlenbeck drift, with parameter $b$ (we take $b>0$ for inward O-U and
$b<0$ for outward O-U). This work has been motivated by [4], where a similar
model was studied, but without the drift component.
  We show that the large time behavior of the system depends on the interaction
and the drift in a nontrivial way. Our method provides, inter alia, the SLLN
for the non-interactive branching (inward) O-U process.
  First, regardless of attraction ($\gamma >0$) or repulsion ($\gamma <0$),
a.s., as time tends to infinity, the center of mass of $Z$
  (i) converges to the origin, when $b>0$;
  (ii) escapes to infinity exponentially fast (rate $|b|$), when $b<0$.
  We then analyze $Z$ as viewed from the center of mass, and finally, for the
system as a whole, we show a number of results/conjectures regarding the long
term behavior of the system; some of these are scaling limits, while some
others concern local extinction.


title: The edge-isorperimetric problem on Sierpinski graphs

abstract:
  Some families of graphs, such as the n-cubes and Sierpinski gaskets, are
self-similar. In this paper we show how such recursive structure can be used
systematically to prove isoperimetric theorems.


title:
Analysis of a model microswimmer with applications to blebbing cells and
  mini-robots

abstract:
  Recent research has shown that motile cells can adapt their mode of
propulsion depending on the environment in which they find themselves. One mode
is swimming by blebbing or other shape changes, and in this paper we analyze a
class of models for movement of cells by blebbing and of nano- robots in a
viscous fluid at low Reynolds number. At the level of individuals, the shape
changes comprise volume exchanges between connected spheres that can control
their separation, which are simple enough that significant analytical results
can be obtained. The goal is to understand how the efficiency of move- ment
depends on the amplitude and period of the volume exchanges when the spheres
approach closely during a cycle. Previous analyses were predicated on wide
separation, and we show that the speed in- creases significantly as the
separation decreases due to the strong hydrodynamic interactions between
spheres in close proximity. The scallop theorem asserts that at least two
degrees of freedom are needed to produce net motion in a cyclic sequence of
shape changes, and we show that these degrees can reside in different swimmers
whose collective motion is studied. We also show that different combinations of
mode sharing can lead to significant differences in the translation and
performance of pairs of swimmers.


title:
Sub-1-us, Sub-20-nJ Pattern Classification in a Mixed-Signal Circuit
  Based on Embedded 180-nm Floating-Gate Memory Cell Arrays

abstract:
  We have designed, fabricated, and successfully tested a prototype
mixed-signal, 28x28-binary-input, 10-output, 3-layer neuromorphic network ("MLP
perceptron"). It is based on embedded nonvolatile floating-gate cell arrays
redesigned from a commercial 180-nm NOR flash memory. The arrays allow precise
(~1%) individual tuning of all memory cells, having long-term analog-level
retention and low noise. Each array performs a very fast and energy-efficient
analog vector-by-matrix multiplication, which is the bottleneck for signal
propagation in most neuromorphic networks. All functional components of the
prototype circuit, including 2 synaptic arrays with 101,780 floating-gate
synaptic cells, 74 analog neurons, and the peripheral circuitry for weight
adjustment and I/O operations, have a total area below 1 mm^2. Its testing on
the common MNIST benchmark set (at this stage, with a relatively low weight
import precision) has shown a classification fidelity of 94.65%, close to the
96.2% obtained in simulation. The classification of one pattern takes less than
1 us time and ~20 nJ energy - both numbers much better than for digital
implementations of the same task. Estimates show that this performance may be
further improved using a better neuron design and a more advanced memory
technology, leading to a >10^2 advantage in speed and a >10^4 advantage in
energy efficiency over the state-of-the-art purely digital (GPU and custom)
circuits, at classification of large, complex patterns.


title:
Energy Efficiency Optimization of Channel Access Probabilities in IEEE
  802.15.6 UWB WBANs

abstract:
  Energy efficiency is essential for Wireless Body Area Network (WBAN)
applications because of the battery-operated nodes. Other requirements such as
throughput, delay, quality of service, and security levels also need to be
considered in optimizing the network design. In this paper, we study the case
in which the nodes access the medium probabilistically and we formulate an
energy efficiency optimization problem under the rate and access probability
constraints for IEEE 802.15.6 Impulse Radio Ultra-wideband (IR-UWB) WBANs. The
proposed algorithm, dubbed Energy Efficiency Optimization of Channel Access
Probabilities (EECAP), determines the optimal access probability and payload
frame size for each node. The simulation results show that our algorithm
rapidly converges to the optimal solution. We also provide detailed insights on
the relationship between the optimal access probabilities and other network
parameters such as the link distance, the number of nodes, and the minimum rate
constraints.


title: Diffusion measurement from observed transverse beam echoes

abstract:
  We study the measurement of transverse diffusion through beam echoes. We
revisit earlier observations of echoes in RHIC and apply an updated theoretical
model to these measurements. We consider three possible models for the
diffusion coefficient and show that only one is consistent with measured echo
amplitudes and pulse widths. This model allows us to parameterize the diffusion
coefficients as functions of bunch charge. We demonstrate that echoes can be
used to measure diffusion much quicker than present methods and could be useful
to a variety of hadron synchrotrons.


title: Validating Simplified Processor Models in Architectural Studies

abstract:
  Cycle-accurate software simulation of multicores with complex
microarchitectures is often excruciatingly slow. People use simplified core
models to gain simulation speed. However, a persistent question is to what
extent the results derived from a simplified core model can be used to
characterize the behavior of a real machine.
  We propose a new methodology of validating simplified simulation models,
which focuses on the trends of metric values across benchmarks and
architectures, instead of errors of absolute metric values. To illustrate this
methodology, we conduct a case study using an FPGA-accelerated cycle-accurate
full system simulator. We evaluated three cache replacement polices on a
10-stage in-order core model, and then re-conducted all the experiments by
substituting a 1-IPC core model for the 10-stage core model. We found that the
1-IPC core model generally produces qualitatively the same results as the
accurate core model except for a few mismatches. We argue that most observed
mismatches were either indistinguishable from experimental noise or
corresponded to the cases where the policy differences even in the accurate
model showed inconclusive results. We think it is fair to use simplified core
models to study a feature once the influence of the simplification is
understood. Additional studies on branch predictors and scaling properties of
multithread benchmarks reinforce our argument. However, the validation of a
simplified model requires a detailed cycle-accurate model!


title:
A Spectral Characterization of Absolutely Norming Operators on S.N.
  Ideals

abstract:
  The class of absolutely norming operators on complex Hilbert spaces of
arbitrary dimensions was introduced in [6] and a spectral characterization
theorem for these operators was established in [11]. In this paper we extend
the concept of absolutely norming operators to various symmetric norms. We
establish a few spectral characterization theorems for operators on complex
Hilbert spaces that are absolutely norming with respect to various symmetric
norms. It is also shown that for many symmetric norms the absolutely norming
operators have the same spectral characterization as proven earlier for the
class of operators that are absolutely norming with respect to the usual
operator norm.
  Finally, we prove the existence of a symmetric norm on the algebra $\mathcal
B (\mathcal H)$ with respect to which even the identity operator does not
attain its norm.


title: Testing decay of astrophysical neutrinos with incomplete information

abstract:
  Neutrinos mix and have mass differences, so decays from one to another must
occur. But how fast? The best direct limits on non-radiative decays, based on
solar and atmospheric neutrinos, are weak, $\tau \gtrsim 10^{-3}$ s ($m$/eV) or
much worse. Greatly improved sensitivity, $\tau \sim 10^3$ s ($m$/eV), will
eventually be obtained using neutrinos from distant astrophysical sources, but
large uncertainties --- in neutrino properties, source properties, and
detection aspects --- do not allow this yet. However, there is a way forward
now. We show that IceCube diffuse neutrino measurements, supplemented by
improvements expected in the near term, can increase sensitivity to $\tau \sim
10$ s ($m$/eV) for all neutrino mass eigenstates. We provide a roadmap for the
necessary analyses and show how to manage the many uncertainties. If limits are
set, this would definitively rule out the long-considered possibility that
neutrino decay affects solar, atmospheric, or terrestrial neutrino experiments.


title:
Superresolution optical magnetic imaging and spectroscopy using
  individual electronic spins in diamond

abstract:
  Nitrogen vacancy (NV) color centers in diamond are a leading modality for
both superresolution optical imaging and nanoscale magnetic field sensing. In
this work, we solve the remaining key challenge of performing optical magnetic
imaging and spectroscopy selectively on multiple NV centers that are located
within a diffraction-limited field-of-view. We use spin-RESOLFT microscopy to
enable precision nanoscale mapping of magnetic field patterns with resolution
down to ~20 nm, while employing a low power optical depletion beam. Moreover,
we use a shallow NV to demonstrate the detection of proton nuclear magnetic
resonance (NMR) signals exterior to the diamond, with 50 nm lateral imaging
resolution and without degrading the proton NMR linewidth.


title: Machine learning force fields: Construction, validation, and outlook

abstract:
  Force fields developed with machine learning methods in tandem with quantum
mechanics are beginning to find merit, given their (i) low cost, (ii) accuracy,
and (iii) versatility. Recently, we proposed one such approach, wherein, the
vectorial force on an atom is computed directly from its environment. Here, we
discuss the multi-step workflow required for their construction, which begins
with generating diverse reference atomic environments and force data, choosing
a numerical representation for the atomic environments, down selecting a
representative training set, and lastly the learning method itself, for the
case of Al. The constructed force field is then validated by simulating complex
materials phenomena such as surface melting and stress-strain behavior - that
truly go beyond the realm of $ab\ initio$ methods both in length and time
scales. To make such force fields truly versatile an attempt to estimate the
uncertainty in force predictions is put forth, allowing one to identify areas
of poor performance and paving the way for their continual improvement.


title: ALMA [CII] detection of a redshift 7 lensed galaxy behind RXJ1347.1-1145

abstract:
  We present the results of ALMA spectroscopic follow-up of a $z=6.765$
Lyman-$\alpha$ emitting galaxy behind the cluster RXJ1347-1145. We report the
detection of [CII]158$\mu$m line fully consistent with the Lyman-$\alpha$
redshift and with the peak of the optical emission. Given the magnification of
$\mu=5.0 \pm 0.3$ the intrinsic (corrected for lensing) luminosity of the [CII]
line is $L_{[CII]} =1.4^{+0.2}_{-0.3} \times 10^7L_{\odot}$, which is ${\sim}5$
times fainter than other detections of $z\sim 7$ galaxies. The result indicates
that low $L_{[CII]}$ in $z\sim 7$ galaxies compared to the local counterparts
might be caused by their low metallicities and/or feedback. The small velocity
off-set ($\Delta v = 20_{-40}^{+140} \rm km/s$) between the Lyman-$\alpha$ and
[CII] line is unusual, and may be indicative of ionizing photons escaping.


title:
Dynamics of suspended rigid aggregating particles in flowing medium:
  theory, analysis and scientific computing

abstract:
  We develop and present a unified multi-scale model (involving three scales of
spatial organisation) to study the dynamics of rigid aggregating particles
suspended in a viscous fluid medium and subject to a steady poiseuille flow. At
micro-level, the theory of adhesion describing the attachment / detachment
kinetics of two rigid spheres coated with binding ligands, is utilized to
describe the collision frequency function. The meso-scale dynamics is outlined
through a continuous general dynamic equation governing the time rate of change
of the particle size distribution function. The micro-meso coupling is achieved
via the balancing of the mesoscale drag forces and couples with the micro-scale
forces associated with the binder kinetics. Inside the macro domain (i.e., a
long pipe), the model is equation free and divided into equal sized patches.
The macroscale solution within each patch is obtained via appropriate
(extrapolatory) coupling and amplitude conditions.


title: On the automated verification of web applications with embedded SQL

abstract:
  A large number of web applications is based on a relational database together
with a program, typically a script, that enables the user to interact with the
database through embedded SQL queries and commands. In this paper, we introduce
a method for formal automated verification of such systems which connects
database theory to mainstream program analysis. We identify a fragment of SQL
which captures the behavior of the queries in our case studies, is
algorithmically decidable, and facilitates the construction of weakest
preconditions. Thus, we can integrate the analysis of SQL queries into a
program analysis tool chain. To this end, we implement a new decision procedure
for the SQL fragment that we introduce. We demonstrate practical applicability
of our results with three case studies, a web administrator, a simple firewall,
and a conference management system.


title: Thermal Conductivity of GaAs/Ge Nanostructures

abstract:
  Superlattices are promising low-dimensional nanomaterials for thermoelectric
technology that is capable of directly converting low-grade heat energy to
useful electrical power. In this work, the thermal conductivities of GaAs/Ge
superlattice nanostructures were investigated systematically in relation to
their morphologies and interfaces. Thermal conductivities were measured using
ultrafast time-domain thermoreflectance and were found to decrease with
increasing interface densities, consistent with our understanding of
microscopic phonon transport in the particle regime. Lower thermal
conductivities were observed in (GaAs)0.77(Ge2)0.23 alloys; transmission
electron microscopy study reveals phase separation in the alloys. These alloys
can be interpreted as fine nanostructures, with length scales comparable to the
periods of very thin superlattices. Our experimental findings help gain
fundamental insight into nanoscale thermal transport in superlattices and are
also useful for future improvement of thermoelectric performance using
superlattice nanostructures.


title:
Prospect Theory for Enhanced Smart Grid Resilience Using Distributed
  Energy Storage

abstract:
  The proliferation of distributed generation and storage units is leading to
the development of local, small-scale distribution grids, known as microgrids
(MGs). In this paper, the problem of optimizing the energy trading decisions of
MG operators (MGOs) is studied using game theory. In the formulated game, each
MGO chooses the amount of energy that must be sold immediately or stored for
future emergencies, given the prospective market prices which are influenced by
other MGOs' decisions. The problem is modeled using a Bayesian game to account
for the incomplete information that MGOs have about each others' levels of
surplus. The proposed game explicitly accounts for each MGO's subjective
decision when faced with the uncertainty of its opponents' energy surplus. In
particular, the so-called framing effect, from the framework of prospect theory
(PT), is used to account for each MGO's valuation of its gains and losses with
respect to an individual utility reference point. The reference point is
typically different for each individual and originates from its past
experiences and future aspirations. A closed-form expression for the Bayesian
Nash equilibrium is derived for the standard game formulation. Under PT, a best
response algorithm is proposed to find the equilibrium. Simulation results show
that, depending on their individual reference points, MGOs can tend to store
more or less energy under PT compared to classical game theory. In addition,
the impact of the reference point is found to be more prominent as the
emergency price set by the power company increases.


title:
Tunable quantum gate between a superconducting atom and a propagating
  microwave photon

abstract:
  We propose a two-qubit quantum logic gate between a superconducting atom and
a propagating microwave photon. The atomic qubit is encoded on its lowest two
levels and the photonic qubit is encoded on its carrier frequencies. The gate
operation completes deterministically upon reflection of a photon, and various
two-qubit gates (SWAP, $\sqrt{\rm SWAP}$, and Identity) are realized through
{\it in situ} control of the drive field. The proposed gate is applicable to
construction of a network of superconducting atoms, which enables gate
operations between non-neighboring atoms.


title:
An oversampling technique for the multiscale finite volume method to
  simulate electromagnetic responses in the frequency domain

abstract:
  In order to reduce the computational cost of the simulation of
electromagnetic responses in geophysical settings that involve highly
heterogeneous media, we develop a multiscale finite volume method with
oversampling for the quasi-static Maxwell's equations in the frequency domain.
We assume a coarse mesh nested within a fine mesh that accurately discretizes
the problem. For each coarse cell, we independently solve a local version of
the original Maxwell's system subject to linear boundary conditions on an
extended domain, which includes the coarse cell and a neighborhood of fine
cells around it. The local Maxwell's system is solved using the fine mesh
contained in the extended domain and the mimetic finite volume method. Next,
these local solutions (basis functions) together with a weak-continuity
condition are used to construct a coarse-mesh version of the global problem.
The basis functions can be used to obtain the fine-mesh details from the
solution of the coarse-mesh problem. Our approach leads to a significant
reduction in the size of the final system of equations and the computational
time, while accurately approximating the behavior of the fine-mesh solutions.
We demonstrate the performance of our method using a synthetic 3D example of a
mineral deposit.


title:
Numerical approximation of the Frobenius-Perron operator using the
  finite volume method

abstract:
  We develop a finite-dimensional approximation of the Frobenius-Perron
operator using the finite volume method applied to the continuity equation for
the evolution of probability. A Courant-Friedrichs-Lewy condition ensures that
the approximation satisfies the Markov property, while existing convergence
theory for the finite volume method guarantees convergence of the discrete
operator to the continuous operator as mesh size tends to zero. Properties of
the approximation are demonstrated in a computed example of sequential
inference for the state of a low-dimensional mechanical system when
observations give rise to multi-modal distributions.


title: Edges and Vertices in a Unique Signed Circle in a Signed Graph

abstract:
  We examine the conditions under which a signed graph contains an edge or a
vertex that is contained in a unique negative circle or a unique positive
circle. For an edge in a unique signed circle, the positive and negative case
require the same structure on the underlying graph, but the requirements on the
signature are different. We characterize the structure of the underlying graph
necessary to support such an edge in terms of bridges of a circle. We then use
the results from the edge version of the problem to help solve the vertex
version.


title:
Properties of Dark Matter Halos as a Function of Local Environment
  Density

abstract:
  We study how properties of discrete dark matter halos depend on halo
environment, characterized by the mass density around the halos on scales from
0.5 to 16 $h^{-1}{\rm Mpc}$. We find that low mass halos (those less massive
than the characteristic mass $M_{\rm C}$ of halos collapsing at a given epoch)
in high-density environments have lower accretion rates, lower spins, higher
concentrations, and rounder shapes than halos in median density environments.
Halos in median and low-density environments have similar accretion rates and
concentrations, but halos in low density environments have lower spins and are
more elongated. Halos of a given mass in high-density regions accrete material
earlier than halos of the same mass in lower-density regions. All but the most
massive halos in high-density regions are losing mass (i.e., being stripped) at
low redshifts, which causes artificially lowered NFW scale radii and increased
concentrations. Tidal effects are also responsible for the decreasing spins of
low mass halos in high density regions at low redshifts $z < 1$, by
preferentially removing higher angular momentum material from halos. Halos in
low-density regions have lower than average spins because they lack nearby
halos whose tidal fields can spin them up. We also show that the simulation
density distribution is well fit by an Extreme Value Distribution, and that the
density distribution becomes broader with cosmic time.


title: New Inversion Formulas for Radon Transforms on Affine Grassmannians

abstract:
  We obtain new inversion formulas for the Radon transform and the
corresponding dual transform acting on affine Grassmann manifolds of planes in
$R^n$. The consideration is performed in full generality on continuous
functions and functions belonging to $L^p$ spaces.


title:
On Bounded Rationality in Cyber-Physical Systems Security:
  Game-Theoretic Analysis with Application to Smart Grid Protection

abstract:
  In this paper, a general model for cyber-physical systems (CPSs), that
captures the diffusion of attacks from the cyber layer to the physical system,
is studied. In particular, a game-theoretic approach is proposed to analyze the
interactions between one defender and one attacker over a CPS. In this game,
the attacker launches cyber attacks on a number of cyber components of the CPS
to maximize the potential harm to the physical system while the system operator
chooses to defend a number of cyber nodes to thwart the attacks and minimize
potential damage to the physical side. The proposed game explicitly accounts
for the fact that both attacker and defender can have different computational
capabilities and disparate levels of knowledge of the system. To capture such
bounded rationality of attacker and defender, a novel approach inspired from
the behavioral framework of cognitive hierarchy theory is developed. In this
framework, the defender is assumed to be faced with an attacker that can have
different possible thinking levels reflecting its knowledge of the system and
computational capabilities. To solve the game, the optimal strategies of each
attacker type are characterized and the optimal response of the defender facing
these different types is computed. This general approach is applied to smart
grid security considering wide area protection with energy markets
implications. Numerical results show that a deviation from the Nash equilibrium
strategy is beneficial when the bounded rationality of the attacker is
considered. Moreover, the results show that the defender's incentive to deviate
from the Nash equilibrium decreases when faced with an attacker that has high
computational ability.


title:
Second-harmonic generation in single-mode integrated waveguides through
  mode-shape modulation

abstract:
  A simple and flexible technique for achieving quasi-phase-matching in
integrated photonic waveguides without periodic poling is proposed and
experimentally demonstrated, referred to as mode-shape-modulation (MSM). It
employs a periodic variation of waveguide width to modulate the intensity of
the pump wave, effectively suppressing out-of-phase light generation. This
technique is applied to the case of second-harmonic generation in thin-film
lithium niobate ridge waveguides. MSM waveguides are fabricated and
characterized with pulsed-pumping in the near-infrared, showing harmonic
generation at a signal wavelength of 784 nm.


title:
Thermodynamics of gravitational clustering phenomena: $N$-body
  self-gravitating gas on the sphere $\mathbb{S}^{3}\subset\mathbb{R}^{4}$

abstract:
  This work is devoted to the thermodynamics of gravitational clustering, a
collective phenomenon with a great relevance in the $N$-body cosmological
problem. We study a classical self-gravitating gas of identical
non-relativistic particles defined on the sphere $\mathbb{S}^{3}\subset
\mathbb{R}^{4}$ by considering gravitational interaction that corresponds to
this geometric space. The analysis is performed within microcanonical
description of an isolated Hamiltonian system by combining continuum
approximation and steepest descend method. According to numerical solution of
resulting equations, the gravitational clustering can be associated with two
microcanonical phase transitions. A first phase transition with a continuous
character is associated with breakdown of $SO(4)$ symmetry of this model. The
second one is the gravitational collapse, whose continuous or discontinuous
character crucially depends on the regularization of short-range divergence of
gravitation potential. We also derive the thermodynamic limit of this model
system, the astrophysical counterpart of Gibbs-Duhem relation, the order
parameters that characterize its phase transitions and the equation of state.
Other interesting behavior is the existence of states with negative heat
capacities, which appear when the effects of gravitation turn dominant for
energies sufficiently low. Finally, we comment the relevance of some of these
results in the study of astrophysical and cosmological situations. Special
interest deserves the gravitational modification of the equation of state due
to the local inhomogeneities of matter distribution. Although this feature is
systematically neglected in studies about Universe expansion, the same one is
able to mimic an effect that is attributed to the dark energy: a negative
pressure.


title: Closed-Field Coronal Heating Driven by Wave Turbulence

abstract:
  To simulate the energy balance of coronal plasmas on macroscopic scales, we
often require the specification of the coronal heating mechanism in some
functional form. To go beyond empirical formulations and to build a more
physically motivated heating function, we investigate the
wave-turbulence-driven (WTD) phenomenology for the heating of closed coronal
loops. Our implementation is designed to capture the large-scale propagation,
reflection, and dissipation of wave turbulence along a loop. The parameter
space of this model is explored by solving the coupled WTD and hydrodynamic
evolution in 1D for an idealized loop. The relevance to a range of solar
conditions is also established by computing solutions for over one hundred
loops extracted from a realistic 3D coronal field. Due to the implicit
dependence of the WTD heating model on loop geometry and plasma properties
along the loop and at the footpoints, we find that this model can significantly
reduce the number of free parameters when compared to traditional empirical
heating models, and still robustly describe a broad range of quiet-sun and
active region conditions. The importance of the self-reflection term in
producing relatively short heating scale heights and thermal nonequilibrium
cycles is also discussed.


title:
Wide bandgap semiconductor from a hidden 2D incommensurate graphene
  phase

abstract:
  Producing a usable semiconducting form of graphene has plagued the
development of graphene electronics for nearly two decades. Now that new
preparation methods have become available, graphene's intrinsic properties can
be measured and the search for semiconducting graphene has begun to produce
results. This is the case of the first graphene "buffer" layer grown on
SiC(0001) presented in this work. We show, contrary to assumptions of the last
forty years, that the buffer graphene layer is not commensurate with SiC. The
new modulated structure we've found resolves a long standing contradiction
where ab initio calculations expect a metallic buffer, while experimentally it
is found to be a semiconductor. Model calculations using the new incommensurate
structure show that the semiconducting $\pi$-band character of the buffer comes
from partially hybridized graphene incommensurate boundaries surrounding
unperturbed graphene islands.


title:
On the topological dimension of the Gromov boundaries of some hyperbolic
  $Out(F_N)$-graphs

abstract:
  We give upper bounds, linear in rank, to the topological dimensions of the
Gromov boundaries of the intersection graph, the free factor graph and the
cyclic splitting graph of a finitely generated free group.


title: Wilson loops in 3d $\mathcal{N}=4$ SQCD from Fermi gas

abstract:
  We study 1/2 BPS Wilson loops in 3d $\mathcal{N}=4$ $U(N)$ Yang-Mills theory
with one adjoint and $N_f$ fundamental hypermultiplets from the Fermi gas
approach. By numerical fitting, we find the first few worldsheet instanton
corrections to the Wilson loops with winding numbers 1, 2 and 3. We verify that
our Fermi gas results are consistent with the matrix model results in the
planar limit.