title:
Beyond Good and Evil: Formalizing the Security Guarantees of
  Compartmentalizing Compilation

abstract:
  Compartmentalization is good security-engineering practice. By breaking a
large software system into mutually distrustful components that run with
minimal privileges, restricting their interactions to conform to well-defined
interfaces, we can limit the damage caused by low-level attacks such as
control-flow hijacking. When used to defend against such attacks,
compartmentalization is often implemented cooperatively by a compiler and a
low-level compartmentalization mechanism. However, the formal guarantees
provided by such compartmentalizing compilation have seen surprisingly little
investigation.
  We propose a new security property, secure compartmentalizing compilation
(SCC), that formally characterizes the guarantees provided by
compartmentalizing compilation and clarifies its attacker model. We reconstruct
our property by starting from the well-established notion of fully abstract
compilation, then identifying and lifting three important limitations that make
standard full abstraction unsuitable for compartmentalization. The connection
to full abstraction allows us to prove SCC by adapting established proof
techniques; we illustrate this with a compiler from a simple unsafe imperative
language with procedures to a compartmentalized abstract machine.


title: Can we still avoid automatic face detection?

abstract:
  After decades of study, automatic face detection and recognition systems are
now accurate and widespread. Naturally, this means users who wish to avoid
automatic recognition are becoming less able to do so. Where do we stand in
this cat-and-mouse race? We currently live in a society where everyone carries
a camera in their pocket. Many people willfully upload most or all of the
pictures they take to social networks which invest heavily in automatic face
recognition systems. In this setting, is it still possible for
privacy-conscientious users to avoid automatic face detection and recognition?
If so, how? Must evasion techniques be obvious to be effective, or are there
still simple measures that users can use to protect themselves?
  In this work, we find ways to evade face detection on Facebook, a
representative example of a popular social network that uses automatic face
detection to enhance their service. We challenge widely-held beliefs about
evading face detection: do our old techniques such as blurring the face region
or wearing "privacy glasses" still work? We show that in general,
state-of-the-art detectors can often find faces even if the subject wears
occluding clothing or even if the uploader damages the photo to prevent faces
from being detected.


title: Quasi-4-Connected Components

abstract:
  We introduce a new decomposition of a graphs into quasi-4-connected
components, where we call a graph quasi-4-connected if it is 3-connected and it
only has separations of order 3 that remove a single vertex. Moreover, we give
a cubic time algorithm computing the decomposition of a given graph.
  Our decomposition into quasi-4-connected components refines the well-known
decompositions of graphs into biconnected and triconnected components. We
relate our decomposition to Robertson and Seymour's theory of tangles by
establishing a correspondence between the quasi-4-connected components of a
graph and its tangles of order 4.


title: Embracing Error to Enable Rapid Crowdsourcing

abstract:
  Microtask crowdsourcing has enabled dataset advances in social science and
machine learning, but existing crowdsourcing schemes are too expensive to scale
up with the expanding volume of data. To scale and widen the applicability of
crowdsourcing, we present a technique that produces extremely rapid judgments
for binary and categorical labels. Rather than punishing all errors, which
causes workers to proceed slowly and deliberately, our technique speeds up
workers' judgments to the point where errors are acceptable and even expected.
We demonstrate that it is possible to rectify these errors by randomizing task
order and modeling response latency. We evaluate our technique on a breadth of
common labeling tasks such as image verification, word similarity, sentiment
analysis and topic classification. Where prior work typically achieves a 0.25x
to 1x speedup over fixed majority vote, our approach often achieves an order of
magnitude (10x) speedup.


title: Universal central extensions of superdialgebras of matrices

abstract:
  We complete the problem of finding the universal central extension in the
category of Leibniz superalgebras of $\mathfrak{sl}(m, n, D)$ when $m+n \geq 3$
and $D$ is a superdialgebra, solving in particular the problem when $D$ is an
associative algebra, superalgebra or dialgebra. To accomplish this task we use
a different method than the standard studied in the literature. We introduce
and use the non-abelian tensor square of Leibniz superalgebras and its
relations with the universal central extension.


title:
Emerging critical behavior at a first-order phase transition rounded by
  disorder

abstract:
  We investigate the two-dimensional four-color Ashkin-Teller model by means of
large-scale Monte-Carlo simulations. We demonstrate that the first-order phase
transition of the clean system is destroyed by random disorder introduced via
site dilution. The critical behavior of the emerging continuous transition
belongs to the clean two-dimensional Ising universality class, apart from
logarithmic corrections. These results confirm perturbative
renormalization-group predictions; they also agree with recent findings for the
three-color case, indicating that the critical behavior is universal.


title:
Superconductor-insulator transition of Josephson-junction arrays on a
  honeycomb lattice in a magnetic field

abstract:
  We study the superconductor to insulator transition at zero temperature in a
Josephson-junction array model on a honeycomb lattice with $f$ flux quantum per
plaquette. The path integral representation of the model corresponds to a
(2+1)-dimensional classical model, which is used to investigate the critical
behavior by extensive Monte Carlo simulations on large system sizes. In
contrast to the model on a square lattice, the transition is found to be first
order for $f=1/3$ and continuous for $f=1/2$ but in a different universality
class. The correlation-length critical exponent is estimated from finite-size
scaling of vortex correlations. The estimated universal conductivity at the
transition is approximately four times its value for $f=0$. The results are
compared with experimental observations on ultrathin superconducting films with
a triangular lattice of nanoholes in a transverse magnetic field.


title:
Contemporaneous broadband observations of three high-redshift BL Lac
  Objects

abstract:
  We have collected broadband spectral energy distributions (SEDs) of three BL
Lac objects, 3FGL J0022.1$-$1855 (z=0.689), 3FGL J0630.9$-$2406 (z >~ 1.239),
and 3FGL J0811.2$-$7529 (z=0.774), detected by Fermi with relatively flat GeV
spectra. By observing simultaneously in the near-IR to hard X-ray band, we can
well characterize the high end of the synchrotron component of the SED. Thus,
fitting the SEDs to synchro-Compton models of the dominant emission from the
relativistic jet, we can constrain the underlying particle properties and
predict the shape of the GeV Compton component. Standard extragalactic
background light (EBL) models explain the high-energy absorption well, with
poorer fits for high UV models. The fits show clear evidence for EBL absorption
in the Fermi spectrum of our highest redshift source 3FGL J0630.9$-$2406. While
synchrotron self-Compton models adequately describe the SEDs, the situation may
be complicated by possible external Compton components. For 3FGL
J0811.2$-$7529, we also discover a nearby serendipitous source in the X-ray
data, which is almost certainly another lower synchrotron peak frequency
($\nu^{sy}_{pk}$) BL Lac, that may contribute flux in the Fermi band. Since our
sources are unusual high-luminosity, moderate $\nu^{sy}_{pk}$ BL Lacs we
compare these quantities and the Compton dominance, the ratio of peak
inverse-Compton to peak synchrotron luminosities ($L^{IC}_{pk}/L^{sy}_{pk}$),
with those of the full Fermi BL Lac population.


title: Learning Granger Causality for Hawkes Processes

abstract:
  Learning Granger causality for general point processes is a very challenging
task. In this paper, we propose an effective method, learning Granger
causality, for a special but significant type of point processes --- Hawkes
process. We reveal the relationship between Hawkes process's impact function
and its Granger causality graph. Specifically, our model represents impact
functions using a series of basis functions and recovers the Granger causality
graph via group sparsity of the impact functions' coefficients. We propose an
effective learning algorithm combining a maximum likelihood estimator (MLE)
with a sparse-group-lasso (SGL) regularizer. Additionally, the flexibility of
our model allows to incorporate the clustering structure event types into
learning framework. We analyze our learning algorithm and propose an adaptive
procedure to select basis functions. Experiments on both synthetic and
real-world data show that our method can learn the Granger causality graph and
the triggering patterns of the Hawkes processes simultaneously.


title: Optimising the K dark filter for the Kunlun Infrared Sky Survey

abstract:
  The Kunlun Infrared Sky Survey will be the first comprehensive exploration of
the time varying Universe in the infrared. A key feature in optimizing the
scientific yield of this ambitious research program is the choice of the survey
passband. In particular the survey aims to maximally exploit the unique thermal
and atmospheric conditions pertaining to the high Antarctic site. By simulating
the expected signal-to-noise for varying filter properties within the so-called
"K_DARK" 2.4um window, filter performance can be tuned and best-case designs
are given covering a range of conditions.


title:
Validity and reliability of free software for bidimensional gait
  analysis

abstract:
  Despite the evaluation systems of human movement that have been advancing in
recent decades, their use are not feasible for clinical practice because it has
a high cost and scarcity of trained operators to interpret their results. An
ideal videogrammetry system should be easy to use, low cost, with minimal
equipment, and fast realization. The CvMob is a free tool for dynamic
evaluation of human movements that express measurements in figures, tables, and
graphics. This paper aims to determine if CvMob is a reliable tool for the
evaluation of two dimensional human gait. This is a validity and reliability
study. The sample was composed of 56 healthy individuals who walked on a
9-meterlong walkway and were simultaneously filmed by CvMob and Vicon system
cameras. Linear trajectories and angular measurements were compared to validate
the CvMob system, and inter and intrarater findings of the same measurements
were used to determine reliability. A strong correlation (rs mean = 0.988) of
the linear trajectories between systems and inter and intrarater analysis were
found. According to the Bland-Altman method, the angles that had good agreement
between systems were maximum flexion and extension (stance and swing) of the
knee and dorsiflexion range of motion and stride length. The CvMob is a
reliable tool for analysis of linear motion and lengths in two-dimensional
evaluations of human gait. The angular measurements demonstrate high agreement
for the knee joint; however, the hip and ankle measurements were limited by
differences between systems.


title: Low Correlation Sequences from Linear Combinations of Characters

abstract:
  Pairs of binary sequences formed using linear combinations of multiplicative
characters of finite fields are exhibited that, when compared to random
sequence pairs, simultaneously achieve significantly lower mean square
autocorrelation values (for each sequence in the pair) and significantly lower
mean square crosscorrelation values. If we define crosscorrelation merit factor
analogously to the usual merit factor for autocorrelation, and if we define
demerit factor as the reciprocal of merit factor, then randomly selected binary
sequence pairs are known to have an average crosscorrelation demerit factor of
$1$. Our constructions provide sequence pairs with crosscorrelation demerit
factor significantly less than $1$, and at the same time, the autocorrelation
demerit factors of the individual sequences can also be made significantly less
than $1$ (which also indicates better than average performance). The sequence
pairs studied here provide combinations of autocorrelation and crosscorrelation
performance that are not achievable using sequences formed from single
characters, such as maximal linear recursive sequences (m-sequences) and
Legendre sequences. In this study, exact asymptotic formulae are proved for the
autocorrelation and crosscorrelation merit factors of sequence pairs formed
using linear combinations of multiplicative characters. Data is presented that
shows that the asymptotic behavior is closely approximated by sequences of
modest length.


title: Coxeter Groups, Ruins, and Weighted $L^2$-cohomology

abstract:
  Given a Coxeter system $(W,S)$ and a multiparameter $\mathbf{q}$ of real
numbers indexed by $S$, one can define the weighted $L^2$-cohomology groups and
associate to them a nonnegative real number called the weighted $L^2$-Betti
number. We show that for ranges of $\mathbf{q}$ depending on certain subgroups
of $W$, the weighted $L^2$-cohomology groups of $W$ are concentrated in low
dimensions. We then prove new vanishing results for the weighted
$L^2$-cohomology of certain low-dimensional Coxeter groups. Our arguments rely
on computing the $L^2$-cohomology of certain complexes called ruins, as well as
the resolution of the Strong Atiyah Conjecture for hyperbolic Coxeter groups.
We conclude by extending to the weighted setting the computations of Davis and
Okun for the case where the nerve of a right-angled Coxeter group is the
barycentric subdivision of a PL-cellulation of an $(n-1)$-manifold with
$n=6,8$.


title:
Test of CP Invariance in vector-boson fusion production of the Higgs
  boson using the Optimal Observable method in the ditau decay channel with the
  ATLAS detector

abstract:
  A test of CP invariance in Higgs boson production via vector-boson fusion
using the method of the Optimal Observable is presented. The analysis exploits
the decay mode of the Higgs boson into a pair of $\tau$ leptons and is based on
20.3 fb$^{-1}$ of proton-proton collision data at $\sqrt{s}$ = 8 TeV collected
by the ATLAS experiment at the LHC. Contributions from CP-violating
interactions between the Higgs boson and electroweak gauge bosons are described
in an effective field theory framework, in which the strength of CP violation
is governed by a single parameter $\tilde{d}$. The mean values and
distributions of CP-odd observables agree with the expectation in the Standard
Model and show no sign of CP violation. The CP-mixing parameter $\tilde{d}$ is
constrained to the interval [-0.11,0.05] at 68% confidence level, consistent
with the Standard Model expectation of $\tilde{d}=0$.


title: On some finiteness results for unramified cohomology

abstract:
  We obtain several finiteness results for the unramified cohomology of
function fields of algebraic varieties defined over fields of type (F'_m), a
class that includes algebraically closed fields, finite fields, local fields,
and some higher local fields of characteristic 0.


title:
Recursive Recovery of Sparse Signal Sequences from Compressive
  Measurements: A Review

abstract:
  In this article, we review the literature on design and analysis of recursive
algorithms for reconstructing a time sequence of sparse signals from
compressive measurements. The signals are assumed to be sparse in some
transform domain or in some dictionary. Their sparsity patterns can change with
time, although, in many practical applications, the changes are gradual. An
important class of applications where this problem occurs is dynamic projection
imaging, e.g., dynamic magnetic resonance imaging (MRI) for real-time medical
applications such as interventional radiology, or dynamic computed tomography.


title: Beyond a phenomenological description of magnetostriction

abstract:
  We use ultrafast x-ray and electron diffraction to disentangle spin-lattice
coupling of granular FePt in the time domain. The reduced dimensionality of
single-crystalline FePt nanoparticles leads to strong coupling of magnetic
order and a highly anisotropic three-dimensional lattice motion characterized
by a- and b-axis expansion and c-axis contraction. The resulting increase of
the FePt lattice tetragonality, the key quantity determining the energy barrier
between opposite FePt magnetization orientations, persists for tens of
picoseconds. These results suggest a novel approach to laser-assisted magnetic
switching in future data storage applications.


title: Hyper-Structured Illumination

abstract:
  We present a new approach to super-resolution optical imaging, based on
structured illumination in hyperbolic media. The proposed system allows for
planar geometry, has unlimited field of view, and is robust with respect to
optical noise and material losses.


title:
Quasi Linear Codes: Application to Point-to-Point and Multi-Terminal
  Source Coding

abstract:
  A new ensemble of structured codes is introduced. These codes are called
Quasi Linear Codes (QLC). The QLC's are constructed by taking subsets of linear
codes. They have a looser structure compared to linear codes and are not closed
under addition. We argue that these codes provide gains in terms of achievable
Rate-Distortions (RD) in different multi-terminal source coding problems. We
derive the necessary covering bounds for analyzing the performance of QLC's. We
then consider the Multiple-Descriptions (MD) problem, and prove through an
example that the application of QLC's gives an improved achievable RD region
for this problem. Finally, we derive an inner bound to the achievable RD region
for the general MD problem which strictly contains all of the previous known
achievable regions.


title: A smoothness test for higher codimensions

abstract:
  Based on an idea in Hironaka's proof of resolution of singularities, we
present an algorithmic smoothness test for algebraic varieties. The test is
inherently parallel and does not involve the calculation of codimension-sized
minors of the Jacobian matrix of the variety. We also describe a hybrid method
which combines the new method with the Jacobian criterion, thus making use of
the strengths of both approaches. We have implemented all algorithms in the
computer algebra system Singular, and compare the different approaches with
respect to timings and memory usage. The test examples originate from questions
in algebraic geometry, where the use of the Jacobian criterion is impractical
due to the number and size of the minors involved.


title:
Pathwise functional calculus and applications to continuous-time finance
  (PhD thesis)

abstract:
  This thesis develops a mathematical framework for the analysis of
continuous-time trading strategies which, in contrast to the classical setting
of continuous-time finance, does not rely on stochastic integrals or other
probabilistic notions. Using the recently developed 'non-anticipative
functional calculus', we first develop a pathwise definition of the gain
process for a large class of continuous-time trading strategies which include
the important class of delta-hedging strategies, as well as a pathwise
definition of the self-financing condition. Using these concepts, we propose a
framework for analyzing the performance and robustness of delta-hedging
strategies for path-dependent derivatives across a given set of scenarios. Our
setting allows for general path-dependent payoffs and does not require any
probabilistic assumption on the dynamics of the underlying asset, thereby
extending previous results on robustness of hedging strategies in the setting
of diffusion models. We obtain a pathwise formula for the hedging error for a
general path-dependent derivative and provide sufficient conditions ensuring
the robustness of the delta hedge. We show in particular that robust hedges may
be obtained in a large class of continuous exponential martingale models under
a vertical convexity condition on the payoff functional. Under the same
conditions, we show that discontinuities in the underlying asset always
deteriorate the hedging performance. These results are applied to the case of
Asian options and barrier options. The last chapter, independent of the rest of
the thesis, proposes a novel method, jointly developed with Andrea Pascucci and
Stefano Pagliarani, for analytical approximations in local volatility models
with L\'evy jumps. Numerical tests confirm the effectiveness of the method.


title:
Conservation laws and flux bounds for gravitational perturbations of the
  Schwarzschild metric

abstract:
  We derive an energy conservation law for the system of gravitational
perturbations on the Schwarzschild spacetime expressed in a double null gauge.
The resulting identity involves only first derivatives of the metric
perturbation. Exploiting the gauge invariance up to boundary terms of the
fluxes that appear, we are able to establish positivity of the flux on any
outgoing null hypersurface to the future of the initial data. This allows us to
bound the total energy flux through any such hypersurface, including the event
horizon, in terms of initial data. We similarly bound the total energy radiated
to null infinity. Our estimates provide a direct approach to a weak form of
stability, thereby complementing the proof of the full linear stability of the
Schwarzschild solution recently obtained in [M. Dafermos, G. Holzegel and I.
Rodnianski \emph{The linear stability of the Schwarzschild solution to
gravitational perturbations}, arXiv:1601.06467].


title: Geometrical aspects of the Lie Algebra S-Expansion Procedure

abstract:
  In this article it is shown that S-Expansion procedure affects the geometry
of a Lie group, changing it an leading us to the geometry of another Lie group
with higher dimensionality. Is outlined, via an example, a method for
determining the semigroup, which would provide a Lie algebra from another.
Finally, it is proved that the Lie algebra obtained from another Lie algebra
via S-Expansion is a non-simple Lie algebra. I


title:
Precision measurement of the nuclear polarization in laser-cooled,
  optically pumped $^{37}\mathrm{K}$

abstract:
  We report a measurement of the nuclear polarization of laser-cooled,
optically-pumped $^{37}\mathrm{K}$ atoms which will allow us to precisely
measure angular correlation parameters in the beta-decay of the same atoms.
These results will be used to test the $V-A$ framework of the weak interaction
at high precision. At the TRIUMF Neutral Atom Trap (TRINAT), a magneto-optical
trap (MOT) confines and cools neutral $^{37}\mathrm{K}$ atoms and optical
pumping spin-polarizes them. We monitor the nuclear polarization of the same
atoms that are decaying in situ by photoionizing a small fraction of the
partially polarized atoms and then use the standard optical Bloch equations to
model their population distribution. We obtain an average nuclear polarization
of $P = 0.9913\pm0.0008$, which is significantly more precise than previous
measurements with this technique. Since our current measurement of the
beta-asymmetry has $0.2\%$ statistical uncertainty, the polarization
measurement reported here will not limit its overall uncertainty. This result
also demonstrates the capability to measure the polarization to $<0.1\%$,
allowing for a measurement of angular correlation parameters to this level of
precision, which would be competitive in searches for new physics.


title: Iterative actions of normal operators

abstract:
  Let $A$ be a normal operator in a Hilbert space $\mathcal{H}$, and let
$\mathcal{G} \subset \mathcal{H}$ be a countable set of vectors. We investigate
the relations between $A$, $\mathcal{G}$ , and $L$ that makes the system of
iterations $\{A^ng: g\in \mathcal{G},\;0\leq n< L(g)\}$ complete, Bessel, a
basis, or a frame for $\mathcal{H}$. The problem is motivated by the dynamical
sampling problem and is connected to several topics in functional analysis,
including, frame theory and spectral theory. It also has relations to topics in
applied harmonic analysis including, wavelet theory and time-frequency
analysis.


title:
Hierarchical multivariate space-time methods for modeling counts with an
  application to stroke mortality data

abstract:
  Geographic patterns in stroke mortality have been studied as far back as the
1960s, when a region of the southeastern United States became known as the
"stroke belt" due to its unusually high rates of stroke mortality. While stroke
mortality rates are known to increase exponentially with age, an investigation
of spatiotemporal trends by age group at the county-level is daunting due to
the preponderance of small population sizes and/or few stroke events by age
group. Here, we harness the power of a complex, nonseparable multivariate
space-time model which borrows strength across space, time, and age group to
obtain reliable estimates of yearly county-level mortality rates from US
counties between 1973 and 2013 for those aged 65+. Furthermore, we propose an
alternative metric for measuring changes in event rates over time which
accounts for the full trajectory of a county's event rates, as opposed to
simply comparing the rates at the beginning and end of the study period. In our
analysis of the stroke data, we identify differing spatiotemporal trends in
mortality rates across age groups, shed light on the gains achieved in the Deep
South, and provide evidence that a separable model is inappropriate for these
data.


title:
Socially Impaired Robots: Human Social Disorders and Robots'
  Socio-Emotional Intelligence

abstract:
  Social robots need intelligence in order to safely coexist and interact with
humans. Robots without functional abilities in understanding others and unable
to empathise might be a societal risk and they may lead to a society of
socially impaired robots. In this work we provide a survey of three relevant
human social disorders, namely autism, psychopathy and schizophrenia, as a
means to gain a better understanding of social robots' future capability
requirements. We provide evidence supporting the idea that social robots will
require a combination of emotional intelligence and social intelligence, namely
socio-emotional intelligence. We argue that a robot with a simple
socio-emotional process requires a simulation-driven model of intelligence.
Finally, we provide some critical guidelines for designing future
socio-emotional robots.


title: The Independence of Markov's Principle in Type Theory

abstract:
  In this paper, we show that Markov's principle is not derivable in dependent
type theory with natural numbers and one universe. One way to prove this would
be to remark that Markov's principle does not hold in a sheaf model of type
theory over Cantor space, since Markov's principle does not hold for the
generic point of this model. Instead we design an extension of type theory,
which intuitively extends type theory by the addition of a generic point of
Cantor space. We then show the consistency of this extension by a normalization
argument. Markov's principle does not hold in this extension, and it follows
that it cannot be proved in type theory.


title:
The first gravitational-wave source from the isolated evolution of two
  40-100 Msun stars

abstract:
  The merger of two massive 30 Msun black holes has been detected in
gravitational waves (1,GW150914). This discovery validates recent predictions
(2-4) that massive binary black holes would constitute the first detection.
However, previous calculations have not sampled the relevant binary black hole
progenitors---massive, low-metallicity binary stars---with sufficient accuracy
and input physics to enable robust predictions to better than several orders of
magnitude (5-10). Here we report a suite of high-precision numerical
simulations of binary black hole formation via the evolution of isolated binary
stars, providing a framework to interpret GW150914 and predict the properties
of subsequent binary black hole gravitational-wave events. Our models imply
that these events form in an environment where the metallicity is less than 10
percent of solar; have initial masses of 40-100 Msun; and interact through mass
transfer and a common envelope phase. Their progenitors likely form either at 2
Gyr, or somewhat less likely, at 11 Gyr after the Big Bang. Most binary black
holes form without supernova explosions, and their spins are nearly unchanged
since birth, but do not have to be parallel. The classical field formation of
binary black holes proposed in this study, with low natal kicks and restricted
common envelope evolution, produces 40 times more binary black holes than
dynamical formation channels involving globular clusters (11) and is comparable
to the rate from homogeneous evolution channels (12-15). Our calculations
predict detections of about 1,000 black hole mergers per year with total mass
of 20-80 Msun once second generation ground-based gravitational wave
observatories reach full sensitivity.


title: On Small Gaps in the Length Spectrum

abstract:
  We discuss upper and lower bounds for the size of gaps in the length spectrum
of negatively curved manifolds. For manifolds with algebraic generators for the
fundamental group, we establish the existence of exponential lower bounds for
the gaps. On the other hand, we show that the existence of arbitrary small gaps
is topologically generic: this is established both for surfaces of constant
negative curvature (Theorem 3.1), and for the space of negatively curved
metrics (Theorem 4.1). While arbitrary small gaps are topologically generic, it
is plausible that the gaps are not too small for almost every metric. One
result in this direction is presented in Section 5.


title:
The Cauchy problem for the shallow water typ equations in low regularity
  spaces on the circle

abstract:
  In this paper, we investigate the Cauchy problem for the shallow water type
equation \[ u_{t}+\partial_{x}^{3}u
  + \frac{1}{2}\partial_{x}(u^{2})+\partial_{x}
  (1-\partial_{x}^{2})^{-1}\left[u^{2}+\frac{1}{2}u_{x}^{2}\right]=0,x\in
{\mathbf T}=\R/2\pi
  \lambda \] with low regularity data in the periodic settings and
$\lambda\geq1$. We prove that the bilinear estimate in $X_{s,b}$ with
$s<\frac{1}{2}$ is invalid.
  We also prove that the problem is locally well-posed in $H^{s}(\mathbf{T})$
with $\frac{1}{6}<s<\frac{1}{2}$ for small initial data. The result of this
paper improves the result of case $j=1$ of Himonas and Misiolek (Communications
in Partial Differential Equations, 23(1998), 123-139.). The new ingredients are
some new function spaces and some new Strichartz estimates.


title:
Anomalous Sound Velocity and Dielectric Shift in Glass: a
  Renormalization Technique for Mechanical and Dielectric Susceptibilities from
  Generic Coupled Block Model

abstract:
  Glass sound velocity shift was observed to be longarithmically temperature
dependent in both relaxation and resonance regimes: $\Delta c/c=\mathcal{C}\ln
T$. It does not monotonically increase with temperature from $T=0$K, but to
reach a maximum around a few Kelvin. Different from tunneling-two-level-system
(TTLS) which gives the slope ratio between relaxation and resonance regimes
$\mathcal{C}^{\rm rel }:\mathcal{C}^{\rm res }=-\frac{1}{2}:1$, we develop a
generic coupled block model to give $\mathcal{C}^{\rm rel }:\mathcal{C}^{\rm
res }=-1:1$, which agrees well with the majority of experimental measurements.
We use electric dipole-dipole interaction to carry out a similar behavior for
glass dielectric constant shift $\Delta \epsilon/\epsilon=\mathcal{C}\ln T$.
The slope ratio between relaxation and resonance regimes is $\mathcal{C}^{\rm
rel}:\mathcal{C}^{\rm res}=1:-1$ which agrees with dielectric measurements
quite well. By developing a renormalization procedure for non-elastic
stress-stress and dielectric susceptibilities, we prove these universalities
essentially come from $1/r^3$ long range interactions, independent of
materials' microscopic properties.


title:
Real Space Renormalization: A Generic Microscopic Theory for
  Low-Temperature Avalanches in Static Strained Insulating Glass

abstract:
  We propose a microscopic model to study the avalanche problem of insulating
glass deformed by external static uniform strain below $T=60$K. We use
three-dimensional real-space renormalization procedure to carry out the glass
mechanical susceptibility at macroscopic length scale. We prove the existence
of irreversible stress drops in amorphous materials, corresponding to the steep
positive-negative transitions in glass mechanical susceptibility. We also
obtain the strain directions in which the glass system is brittle. The
irreversible stress drops in glass essentially come from non-elastic
stress-stress interaction which is generated by virtual phonon exchange
process.


title: Data Load Balancing in Heterogeneous Dynamic Networks

abstract:
  Data load balancing is a challenging task in the P2P systems.
  Distributed hash table (DHT) abstraction, heterogeneous nodes, and non
uniform distribution of objects are the reasons to cause load imbalance in
structured P2P overlay networks.
  Previous works solved the load balancing problem by assuming the homogeneous
capabilities of nodes, unawareness of the link latency during transferring
load, and imposing logical structures to collect and reassign load.
  We propose a distributed load balancing algorithm with the topology awareness
feature by using the concept of virtual servers.
  In our approach, each node collects neighborhood load information from
physically close nodes and reassigns virtual servers to overlay nodes based
upon the topology of underlying network.
  Consequently, our approach converges data load balancing quickly and it also
reduces the load transfer cost between nodes.
  Moreover, our approach increases the quality of load balancing among close
nodes of overlay and it also introduces a new tradeoff between the quality of
load balancing and load transfer cost among all overlay nodes.
  Our simulations show that our approach reduces the load transfer cost and it
saves network bandwidth respectively.
  Finally, we show that the in-degree imbalance of nodes, as a consequence of
topology awareness, cannot lead to a remarkable problem in topology aware
overlays.


title:
Evaluating the summer night sky brightness at a research field site on
  Lake Stechlin in northeastern Germany

abstract:
  We report on luminance measurements of the summer night sky at a field site
on a freshwater lake in northeastern Germany (Lake Stechlin) to evaluate the
amount of artificial skyglow from nearby and distant towns in the context of a
planned study on light pollution. The site is located about 70 km north of
Berlin in a rural area possibly belonging to one of the darkest regions in
Germany. Continuous monitoring of the zenith sky luminance between June and
September 2015 was conducted utilizing a Sky Quality Meter. With this device,
typical values for clear nights in the range of 21.5-21.7
mag$_{SQM}/$arcsec$^2$ were measured, which is on the order of the natural sky
brightness during starry nights. On overcast nights, values down to 22.84
mag$_{SQM}/$arcsec$^2$ were obtained, which is about one third as bright as on
clear nights. The luminance measured on clear nights as well as the darkening
with the presence of clouds indicate that there is very little influence of
artificial skyglow on the zenith sky brightness at this location. Furthermore,
fish-eye lens sky imaging luminance photometry was performed with a digital
single-lens reflex camera on a clear night in the absence of moonlight. The
photographs unravel several distant towns as possible sources of light
pollution on the horizon. However, the low level of artificial skyglow makes
the field site at Lake Stechlin an excellent location to study the effects of
skyglow on a lake ecosystem in a controlled fashion.


title: Magnetic field and early evolution of circumstellar disks

abstract:
  The magnetic field plays a central role in the formation and evolution of
circumstellar disks. The magnetic field connects the rapidly rotating central
region with the outer envelope and extracts angular momentum from the central
region during gravitational collapse of the cloud core. This process is known
as magnetic braking. Both analytical and multidimensional simulations have
shown that disk formation is strongly suppressed by magnetic braking in
moderately magnetized cloud cores in the ideal magnetohydrodynamic limit. On
the other hand, recent observations have provided growing evidence of a
relatively large disk several tens of astronomical units in size existing in
some Class 0 young stellar objects. This introduces a serious discrepancy
between the theoretical study and observations. Various physical mechanisms
have been proposed to solve the problem of catastrophic magnetic braking, such
as misalignment between the magnetic field and the rotation axis, turbulence,
and non-ideal effect. In this paper, we review the mechanism of magnetic
braking, its effect on disk formation and early evolution, and the mechanisms
that resolve the magnetic braking problem. In particular, we emphasize the
importance of non-ideal effects. The combination of magnetic diffusion and
thermal evolution during gravitational collapse provides a robust formation
process for the circumstellar disk at the very early phase of protostar
formation. The rotation induced by the Hall effect can supply a sufficient
amount of angular momentum for typical circumstellar disks around T Tauri
stars. By examining the combination of the suggested mechanisms, we conclude
that the circumstellar disks commonly form in the very early phase of protostar
formation.


title: Nuclear binding near a quantum phase transition

abstract:
  How do protons and neutrons bind to form nuclei? This is the central question
of ab initio nuclear structure theory. While the answer may seem as simple as
the fact that nuclear forces are attractive, the full story is more complex and
interesting. In this work we present numerical evidence from ab initio lattice
simulations showing that nature is near a quantum phase transition, a
zero-temperature transition driven by quantum fluctuations. Using lattice
effective field theory, we perform Monte Carlo simulations for systems with up
to twenty nucleons. For even and equal numbers of protons and neutrons, we
discover a first-order transition at zero temperature from a Bose-condensed gas
of alpha particles (4He nuclei) to a nuclear liquid. Whether one has an
alpha-particle gas or nuclear liquid is determined by the strength of the
alpha-alpha interactions, and we show that the alpha-alpha interactions depend
on the strength and locality of the nucleon-nucleon interactions. This insight
should be useful in improving calculations of nuclear structure and important
astrophysical reactions involving alpha capture on nuclei. Our findings also
provide a tool to probe the structure of alpha cluster states such as the Hoyle
state responsible for the production of carbon in red giant stars and point to
a connection between nuclear states and the universal physics of bosons at
large scattering length.

categories: nucl-th cond-mat.quant-gas hep-lat nucl-ex


title: Scattering for radial energy-subcritical wave equations

abstract:
  In this paper, we study the focusing and defocusing energy--subcritical,
nonlinear wave equation in $\mathbb{R}^{1+d}$ with radial initial data for $d =
4,5$. We prove that if a solution remains bounded in the critical space on its
interval of existence, then the solution exists globally and scatters at $\pm
\infty$. The proof follows the concentration compactness/rigidity method
initiated by Kenig and Merle, and the main obstacle is to show the nonexistence
of nonzero solutions with a certain compactness property. A main novelty of
this work is the use of a simple virial argument to rule out the existence of
nonzero solutions with this compactness property rather than channels of energy
arguments that have been proven to be most useful in odd dimensions.


title:
Effects of initial system-environment correlations on open quantum
  system dynamics and state preparation

abstract:
  We investigate the preparation of a target initial state for a two-level
(qubit) system from a system-environment equilibrium or correlated state by an
external field. The system-environment equilibrium or correlated state results
from the inevitable interaction of the system with its environment. An
efficient method in an extended auxiliary Liouville space is introduced to
describe the dynamics of the non-Markovian open quantum system in the presence
of a strong field and an initial system-environment correlation. By using the
time evolutions of the population difference, the state trajectory in the Bloch
sphere representation and the trace distance between two reduced system states
of the open quantum system, the effect of initial system-environment
correlations on the preparation of a system state is studied. We introduce an
upper bound and a lower bound for the trace distance within our perturbation
formalism to describe the diverse behaviors of the dynamics of the trace
distance between various correlated states after the system state preparation.
These bounds that are much more computable than similar bounds in the
literature give a sufficient condition and a necessary condition for the
increase of the trace distance and are related to the witnesses of
non-Markovianity and initial system-bath correlation.


title:
Mergers of Charged Black Holes: Gravitational Wave Events, Short
  Gamma-Ray Bursts, and Fast Radio Bursts

abstract:
  The discoveries of GW 150914, GW 151226, and LVT 151012 suggest that double
black hole (BH-BH) mergers are common in the universe. If at least one of the
two merging black holes carries certain amount of charge, possibly retained by
a rotating magnetosphere, the inspiral of a BH-BH system would drive a global
magnetic dipole normal to the orbital plane. The rapidly evolving magnetic
moment during the merging process would drive a Poynting flux with an
increasing wind power. The magnetospheric activities during the final phase of
the merger would make a fast radio burst (FRB) if the BH charge can be as large
as a factor of $\hat q \sim (10^{-9}-10^{-8})$ of the critical charge $Q_c$ of
the BH. At large radii, dissipation of the Poynting flux energy in the outflow
would power a short duration high-energy transient, which would appear as a
detectable short-duration gamma-ray burst (GRB) if the charge can be as large
as $\hat q \sim (10^{-5}-10^{-4})$. The putative short GRB coincident with GW
150914 recorded by Fermi GBM may be interpreted with this model. Future joint
GW/GRB/FRB searches would lead to a measurement or place a constraint on the
charges carried by isolate black holes.


title: Exciton Dynamics in Monolayer Transition Metal Dichalcogenides

abstract:
  Since the discovery of semiconducting monolayer transition metal
dichalcogenides, a variety of experimental and theoretical studies have been
carried out seeking to understand the intrinsic exciton population decay and
valley relaxation dynamics. Reports of the exciton decay time range from
hundreds of femtoseconds to ten nanoseconds, while the valley depolarization
time can exceed one nanosecond. At present, however, a consensus on the
microscopic mechanisms governing exciton radiative and non-radiative
recombination is lacking. The strong exciton oscillator strength resulting in
up to 20% absorption for a single monolayer points to ultrafast radiative
recombination. However, the low quantum yield and large variance in the
reported lifetimes suggest that non-radiative Auger-type processes obscure the
intrinsic exciton radiative lifetime. In either case, the electron-hole
exchange interaction plays an important role in the exciton spin and valley
dynamics. In this article, we review the experiments and theory that have led
to these conclusions and comment on future experiments that could complement
our current understanding.


title: Gain Modulation by Graphene Plasmons in Aperiodic Lattice Lasers

abstract:
  Two-dimensional graphene plasmon-based technologies will enable the
development of fast, compact and inexpensive active photonic elements because,
unlike plasmons in other materials, graphene plasmons can be tuned via the
doping level. Such tuning is harnessed within terahertz quantum cascade lasers
to reversibly alter their emission. This is achieved in two key steps: First by
exciting graphene plasmons within an aperiodic lattice laser and, second, by
engineering photon lifetimes, linking graphene's Fermi energy with the
round-trip gain. Modal gain and hence laser spectra are highly sensitive to the
doping of an integrated, electrically controllable, graphene layer.
Demonstration of the integrated graphene plasmon laser principle lays the
foundation for a new generation of active, programmable plasmonic metamaterials
with major implications across photonics, material sciences and nanotechnology.


title: Reversed Dickson Polynomials of the Third Kind

abstract:
  Let $p$ be a prime and $q=p^e$. We discuss the properties of the reversed
Dickson polynomial $D_{n,2}(1,x)$ of the third kind. We also give several
necessary conditions for the reversed Dickson polynomial of the third kind
$D_{n,2}(1,x)$ to be a permutation of $\mathbb{F}_{q}$. In particular, we give
explicit evaluation of the sum $\sum_{a\in \mathbb{F}_q}D_{n,2}(1,a)$.


title: Slopes for Pretzel Knots

abstract:
  Using the Hatcher-Oertel algorithm for finding boundary slopes of Montesinos
knots, we prove the Slope Conjecture and the Strong Slope Conjecture for a
family of 3-tangle pretzel knots. More precisely, we prove that the maximal
degrees of the colored Jones polynomial of such knots determine a boundary
slope as predicted by the Slope Conjecture, and that the linear term in the
degrees correspond to the Euler characteristic of an essential surface.


title: The twisted Reidemeister torsion of an iterated torus knot

abstract:
  We calculate the twisted Reidemeister torsion of the complement of an
iterated torus knot associated with a representation of its fundamental group
to the complex special linear group of degree two. We also show that the
twisted Reidemeister torsions associated with various representations appear in
the asymptotic expansion of the colored Jones polynomial.


title:
Safe Pattern Pruning: An Efficient Approach for Predictive Pattern
  Mining

abstract:
  In this paper we study predictive pattern mining problems where the goal is
to construct a predictive model based on a subset of predictive patterns in the
database. Our main contribution is to introduce a novel method called safe
pattern pruning (SPP) for a class of predictive pattern mining problems. The
SPP method allows us to efficiently find a superset of all the predictive
patterns in the database that are needed for the optimal predictive model. The
advantage of the SPP method over existing boosting-type method is that the
former can find the superset by a single search over the database, while the
latter requires multiple searches. The SPP method is inspired by recent
development of safe feature screening. In order to extend the idea of safe
feature screening into predictive pattern mining, we derive a novel pruning
rule called safe pattern pruning (SPP) rule that can be used for searching over
the tree defined among patterns in the database. The SPP rule has a property
that, if a node corresponding to a pattern in the database is pruned out by the
SPP rule, then it is guaranteed that all the patterns corresponding to its
descendant nodes are never needed for the optimal predictive model. We apply
the SPP method to graph mining and item-set mining problems, and demonstrate
its computational advantage.


title: Global Regularity of 2D almost resistive MHD Equations

abstract:
  Whether or not the solution to 2D resistive MHD equations is globally smooth
remains open. This paper establishes the global regularity of solutions to the
2D almost resistive MHD equations, which require the dissipative operators
$\mathcal{L}$ weaker than any power of the fractional Laplacian. The result is
an improvement of the one of Fan et al. (Global Cauchy problem of 2D
generalized MHD equations, Monatsh. Math., 175 (2014), pp. 127-131) which ask
for $\alpha>0, \beta=1$.


title:
Gaussian processes with built-in dimensionality reduction: Applications
  in high-dimensional uncertainty propagation

abstract:
  The prohibitive cost of performing Uncertainty Quantification (UQ) tasks with
a very large number of input parameters can be addressed, if the response
exhibits some special structure that can be discovered and exploited. Several
physical responses exhibit a special structure known as an active subspace
(AS), a linear manifold of the stochastic space characterized by maximal
response variation. The idea is that one should first identify this low
dimensional manifold, project the high-dimensional input onto it, and then link
the projection to the output. In this work, we develop a probabilistic version
of AS which is gradient-free and robust to observational noise. Our approach
relies on a novel Gaussian process regression with built-in dimensionality
reduction with the AS represented as an orthogonal projection matrix that
serves as yet another covariance function hyper-parameter to be estimated from
the data. To train the model, we design a two-step maximum likelihood
optimization procedure that ensures the orthogonality of the projection matrix
by exploiting recent results on the Stiefel manifold. The additional benefit of
our probabilistic formulation is that it allows us to select the dimensionality
of the AS via the Bayesian information criterion. We validate our approach by
showing that it can discover the right AS in synthetic examples without
gradient information using both noiseless and noisy observations. We
demonstrate that our method is able to discover the same AS as the classical
approach in a challenging one-hundred-dimensional problem involving an elliptic
stochastic partial differential equation with random conductivity. Finally, we
use our approach to study the effect of geometric and material uncertainties in
the propagation of solitary waves in a one-dimensional granular system.


title:
The role of master clock stability in scalable quantum information
  processing

abstract:
  Experimentalists seeking to improve the coherent lifetimes of quantum bits
have generally focused on mitigating decoherence mechanisms through, for
example, improvements to qubit designs and materials, and system isolation from
environmental perturbations. In the case of the phase degree of freedom in a
quantum superposition, however, the coherence that must be preserved is not
solely internal to the qubit, but rather necessarily includes that of the qubit
relative to the "master clock" (e.g. a local oscillator) that governs its
control system. In this manuscript we articulate the impact of instabilities in
the master clock on qubit phase coherence, and provide tools to calculate the
contributions to qubit error arising from these processes. We first connect
standard oscillator phase-noise metrics to their corresponding qubit dephasing
spectral densities. We then use representative lab-grade and performance-grade
oscillator specifications to calculate operational fidelity bounds on
trapped-ion and superconducting qubits with relatively slow and fast operation
times. We discuss the relevance of these bounds for quantum error correction in
contemporary experiments and future large-scale quantum information systems,
and discuss potential means to improve master clock stability.


title:
Extending the Nested Parallel Model to the Nested Dataflow Model with
  Provably Efficient Schedulers

abstract:
  The nested parallel (a.k.a. fork-join) model is widely used for writing
parallel programs. However, the two composition constructs, i.e. "$\parallel$"
(parallel) and "$;$" (serial), are insufficient in expressing "partial
dependencies" or "partial parallelism" in a program. We propose a new dataflow
composition construct "$\leadsto$" to express partial dependencies in
algorithms in a processor- and cache-oblivious way, thus extending the Nested
Parallel (NP) model to the \emph{Nested Dataflow} (ND) model. We redesign
several divide-and-conquer algorithms ranging from dense linear algebra to
dynamic-programming in the ND model and prove that they all have optimal span
while retaining optimal cache complexity. We propose the design of runtime
schedulers that map ND programs to multicore processors with multiple levels of
possibly shared caches (i.e, Parallel Memory Hierarchies) and provide
theoretical guarantees on their ability to preserve locality and load balance.
For this, we adapt space-bounded (SB) schedulers for the ND model. We show that
our algorithms have increased "parallelizability" in the ND model, and that SB
schedulers can use the extra parallelizability to achieve asymptotically
optimal bounds on cache misses and running time on a greater number of
processors than in the NP model. The running time for the algorithms in this
paper is $O\left(\frac{\sum_{i=0}^{h-1} Q^{*}({\mathsf t};\sigma\cdot M_i)\cdot
C_i}{p}\right)$, where $Q^{*}$ is the cache complexity of task ${\mathsf t}$,
$C_i$ is the cost of cache miss at level-$i$ cache which is of size $M_i$,
$\sigma\in(0,1)$ is a constant, and $p$ is the number of processors in an
$h$-level cache hierarchy.


title: On functors between categories with colored morphisms

abstract:
  In this paper, we consider categories with colored morphisms and functors
such that morphisms assigned to morphisms with a common color have a common
color. In this paper, we construct a morphism-colored functor such that any
morphism-colored functor from a given small morphism-colored groupoid to any
discrete morphism-colored category factors through it. We also apply the main
result to a schemoid constructed from a Hamming scheme.


title:
Identification of Candidate Millisecond Pulsars from Fermi LAT
  Observations

abstract:
  We report our detailed data analysis for 39 $\gamma$-ray sources selected
from the 992 unassociated sources in the \textit{Fermi} Large Area Telescope
(LAT) third source catalog. The selection criteria, which were set for finding
candidate millisecond pulsars (MSPs), are non-variables with curved spectra and
$>$5$^{\circ}$ Galactic latitudes. From our analysis, 24 sources were found to
be point-like sources not contaminated by background or nearby unknown sources.
Three of them, J1544.6$-$1125, J1625.1$-$0021, and J1653.6$-$0158, have been
previously studied, indicating that they are likely MSPs. The spectra of
J0318.1+0252 and J2053.9+2922 do not have properties similar to that of known
$\gamma$-ray MSPs, and we thus suggest that they are not MSPs. Analysis of
archival X-ray data for most of the 24 sources were also conducted. Four
sources were found with X-ray objects in their error circles, and 16 with no
detection. The ratios between the $\gamma$-ray fluxes and X-ray fluxes or flux
upper limits are generally lower than those of the known $\gamma$-ray MSPs,
suggesting that if the $\gamma$-ray sources are MSPs, none of the X-ray objects
are the counterparts. Deep X-ray or radio observations of these sources are
needed in order to identify their MSP nature.


title:
\pi-flux Dirac bosons and topological edge excitations in a bosonic
  chiral p-wave superfluid

abstract:
  We study the topological properties of elementary excitations in a staggered
$p_x \pm i p_y$ Bose-Einstein condensate realized in recent orbital optical
lattice experiments. The condensate wave function may be viewed as a
configuration space variant of the famous $p_x+ ip_y$ momentum space order
parameter of strontium ruthenate superconductors. We show that its elementary
excitation spectrum possesses Dirac bosons with $\pi$ Berry flux. Remarkably,
if we induce a population imbalance between the $p_x+ip_y$ and $p_x-ip_y$
condensate components, a gap opens up in the excitation spectrum resulting in a
nonzero Chern invariant and topologically protected edge excitation modes. We
give a detailed description on how our proposal can be implemented with
standard experimental technology.


title:
Finite Element-Based Structural Optimization of Large System Models
  Under Buckling Constraints

abstract:
  Optimization of large structures of multiple components is essential to many
industries for minimizing mass, especially the design of aerospace vehicles.
Optimizing a single primary load member independently of all other primary
structures is an incomplete process, due to the redistribution of internal
loads, as the stiffness distribution changes. That is, optimizing a component
changes joint loads, which then calls for a new optimization - changing
internal loads changes the optimum. This is particularly evident under buckling
(stability) constraints. The goal is to develop a finite element-based
optimization approach which can be used to optimize each component of a large,
primary structure assembly. The optimization objective function will be to
minimize mass for the system, and the constraints will be both stress
constraints as well as buckling constraints. The research aims to improve both
the solution and practical usability of these models. The system of interest is
a spacecraft fuselage, of which the member components are panels throughout the
structure. We present analyses of several main optimization methods, and define
a new algorithm to solve this problem, eigenOpt.


title:
Artificial Perfect Electric Conductor-Perfect Magnetic Conductor
  Anisotropic Metasurface for Generating Orbital Angular Momentum of Microwave
  with Nearly Perfect Conversion Efficiency

abstract:
  Orbital angular momentum (OAM) is a promising degree of freedom for
fundamental studies in electromagnetics and quantum mechanics. The unlimited
state space of OAM shows a great potential to enhance channel capacities of
classical and quantum communications. By exploring the Pancharatnam-Berry phase
concept and engineering anisotropic scatterers in a metasurface with spatially
varying orientations, a plane wave with zero OAM can be converted to a vortex
beam carrying nonzero OAM. In this paper, we proposed two types of novel PEC
(perfect electric conductor)-PMC (perfect magnetic conductor) anisotropic
metasurfaces. One is composed of azimuthally continuous loops and the other is
constructed by azimuthally discontinuous dipole scatterers. Both types of
metasurfaces are mounted on a mushroom-type high impedance surface. Compared to
previous metasurface designs for generating OAM, the proposed ones achieve
nearly perfect conversion efficiency. In view of the eliminated vertical
component of electric field, the continuous metasurface shows very smooth phase
pattern at the near-field region, which cannot be achieved by convectional
metasurfaces composed of discrete scatterers. On the other hand, the
metasurface with discrete dipole scatterers shows a great flexibility to
generate OAM with arbitrary topological charges. Our work is fundamentally and
practically important to high-performance OAM generation.


title: Empirical formula of crustal torsional oscillations

abstract:
  Crustal torsional oscillations depend on not only crust properties but also
the stellar mass and radius. Thus, one could extract stellar information by
identifying the observed frequencies of stellar oscillations with the crustal
torsional oscillations. Owing to the confinement of torsional oscillations
inside the crust region of neutron stars, we successfully derive an empirical
formula for the fundamental crustal torsional oscillations as a function of the
stellar mass, radius, the so-called slope parameter of the nuclear symmetry
energy, and the angular index of oscillations, with which one can estimate the
frequencies with high accuracy. This empirical formula could be valuable in
both the astrophysics and nuclear physics communities.


title: Degenerate spacetimes in first order gravity

abstract:
  We present a systematic framework to obtain the most general solutions of the
equations of motion in first order gravity theory with degenerate tetrads.
There are many possible solutions. Generically, these exhibit non-vanishing
torsion even in the absence of any matter coupling. These solutions are shown
to contain a special set of eight configurations which are associated with the
homogeneous model three-geometries of Thurston.


title: Circuit Evaluation for Finite Semirings

abstract:
  The computational complexity of the circuit evaluation problem for finite
semirings is considered, where semirings are not assumed to have an additive or
multiplicative identity. The following dichotomy is shown: If a finite semiring
is such that (i) the multiplicative semigroup is solvable and (ii) it does not
contain a subsemiring with an additive identity $0$ and a multiplicative
identity $1 \neq 0$, then the circuit evaluation problem for the semiring is in
$\mathsf{DET} \subseteq \mathsf{NC}^2$. In all other cases, the circuit
evaluation problem is $\mathsf{P}$-complete.


title: Tutte polynomials and random-cluster models in Bernoulli cell complexes

abstract:
  This paper studies Bernoulli cell complexes from the perspective of
persistent homology, Tutte polynomials, and random-cluster models. Following
the previous work [9], we first show the asymptotic order of the expected
lifetime sum of the persistent homology for the Bernoulli cell complex process
on the $\ell$-cubical lattice. Then, an explicit formula of the expected
lifetime sum using the Tutte polynomial is derived. Furthermore, we study a
higher dimensional generalization of the random-cluster model derived from the
Edwards-Sokal type coupling, and show some basic results such as the positive
association and the relation to the Tutte polynomial.


title: An Illustrated Introduction to the Truncated Fourier Transform

abstract:
  The Truncated Fourier Transform (TFT) is a variation of the Discrete Fourier
Transform (DFT/FFT) that allows for input vectors that do NOT have length $2^n$
for $n$ a positive integer. We present the univariate version of the TFT,
originally due to Joris van der Hoeven, heavily illustrating the presentation
in order to make these methods accessible to a broader audience.


title:
Correlating the Energetics and Atomic Motions of the Metal-Insulator
  Transition of M1 Vanadium Dioxide

abstract:
  Materials that undergo reversible metal-insulator transitions are obvious
candidates for new generations of devices. For such potential to be realised,
the underlying microscopic mechanisms of such transitions must be fully
determined. In this work we probe the correlation between the energy landscape
and electronic structure of the metal-insulator transition of vanadium dioxide
and the atomic motions occurring using first principles calculations and high
resolution X-ray diffraction. Calculations find an energy barrier between the
high and low temperature phases corresponding to contraction followed by
expansion of the distances between vanadium atoms on neighbouring sub-lattices.
X-ray diffraction reveals anisotropic strain broadening in the low temperature
structure's crystal planes, however only for those with spacings affected by
this compression/expansion. GW calculations reveal that traversing this barrier
destabilises the bonding/anti-bonding splitting of the low temperature phase.
This precise atomic description of the origin of the energy barrier separating
the two structures will facilitate more precise control over the transition
characteristics for new applications and devices.


title:
Interfacial effects revealed by ultrafast relaxation dynamics in
  BiFeO$_{3}$/YBa$_{2}$Cu$_{3}$O$_{7}$ bilayers

abstract:
  The temperature dependence of the relaxation dynamics in the bilayer thin
film heterostructure composed of multiferroic BiFeO$_{3}$ (BFO) and
superconducting YBa$_{2}$Cu$_{3}$O$_{7}$ (YBCO) grown on a (001) SrTiO$_{3}$
substrate is studied by a time-resolved pump-probe technique, and compared with
that of pure YBCO thin film grown under the same growth conditions. The
superconductivity of YBCO is found to be retained in the heterostructure. We
observe a speeding up of the YBCO recombination dynamics in the superconducting
state of the heterostructure, and attribute it to the presence of weak
ferromagnetism at the BFO/YBCO interface as observed in magnetization data. An
extension of the Rothwarf-Taylor model is used to fit the ultrafast dynamics of
BFO/YBCO, that models an increased quasiparticle occupation of the
ferromagnetic interfacial layer in the superconducting state of YBCO.


title:
A common misapplication of statistical inference: nuisance control with
  null-hypothesis significance tests

abstract:
  Experimental research on behavior and cognition frequently rests on stimulus
or subject selection where not all characteristics can be fully controlled,
even when attempting strict matching. For example, when contrasting patients to
controls, variables such as intelligence or socioeconomic status are often
correlated with patient status. Similarly, when presenting word stimuli,
variables such as word frequency are often correlated with primary variables of
interest. One procedure very commonly employed to control for such nuisance
effects is conducting inferential tests on confounding stimulus or subject
characteristics. For example, if word length is not significantly different for
two stimulus sets, they are considered as matched for word length. Such a test
has high error rates and is conceptually misguided. It reflects a common
misunderstanding of statistical tests: interpreting significance not to refer
to inference about a particular population parameter, but about 1. the sample
in question, 2. the practical relevance of a sample difference (so that a
nonsignificant test is taken to indicate evidence for the absence of relevant
differences). We show inferential testing for assessing nuisance effects to be
inappropriate both pragmatically and philosophically, present a survey showing
its high prevalence, and briefly discuss an alternative in the form of
regression including nuisance variables.


title: Two-Field Born-Infeld with Diverse Dualities

abstract:
  We elaborate on how to build, in a systematic fashion, two-field Abelian
extensions of the Born-Infeld Lagrangian. These models realize the non-trivial
duality groups that are allowed in this case, namely U(2), SU(2) and U(1)xU(1).
For each class, we also construct an explicit example. They all involve an
overall square root and reduce to the Born-Infeld model if the two fields are
identified, but differ in quartic and higher interactions. The U(1)xU(1) and
SU(2) examples recover some recent results obtained with different techniques,
and we show that the U(1)xU(1) model admits an N=1 supersymmetric completion.
The U(2) example includes some unusual terms that are not analytic at the
origin of field space.


title: Adversarial Top-$K$ Ranking

abstract:
  We study the top-$K$ ranking problem where the goal is to recover the set of
top-$K$ ranked items out of a large collection of items based on partially
revealed preferences. We consider an adversarial crowdsourced setting where
there are two population sets, and pairwise comparison samples drawn from one
of the populations follow the standard Bradley-Terry-Luce model (i.e., the
chance of item $i$ beating item $j$ is proportional to the relative score of
item $i$ to item $j$), while in the other population, the corresponding chance
is inversely proportional to the relative score. When the relative size of the
two populations is known, we characterize the minimax limit on the sample size
required (up to a constant) for reliably identifying the top-$K$ items, and
demonstrate how it scales with the relative size. Moreover, by leveraging a
tensor decomposition method for disambiguating mixture distributions, we extend
our result to the more realistic scenario in which the relative population size
is unknown, thus establishing an upper bound on the fundamental limit of the
sample size for recovering the top-$K$ set.


title:
Conflict Resolution: a First-Order Resolution Calculus with Decision
  Literals and Conflict-Driven Clause Learning

abstract:
  This paper defines the (first-order) conflict resolution calculus: an
extension of the resolution calculus inspired by techniques used in modern
SAT-solvers. The resolution inference is restricted to (first-order)
unit-propagation and the calculus is extended with a mechanism for assuming
decision literals and a new inference rule for clause learning, which is a
first-order generalization of the propositional conflict-driven clause learning
(CDCL) procedure. The calculus is sound (because it can be simulated by natural
deduction) and refutationally complete (because it can simulate resolution),
and these facts are proven in detail here.


title:
Shape deformation of lipid membranes by banana-shaped protein rods:
  Comparison with isotropic inclusions and membrane rupture

abstract:
  The assembly of curved protein rods on fluid membranes is studied using
implicit-solvent meshless membrane simulations. As the rod curvature increases,
the rods on a membrane tube assemble along the azimuthal direction first and
subsequently along the longitudinal direction. Here, we show that both
transition curvatures decrease with increasing rod stiffness. For comparison,
curvature-inducing isotropic inclusions are also simulated. When the isotropic
inclusions have the same bending rigidity as the other membrane regions, the
inclusions are uniformly distributed on the membrane tubes and vesicles even
for large spontaneous curvature of the inclusions. However, the isotropic
inclusions with much larger bending rigidity induce shape deformation and are
concentrated on the region of a preferred curvature. For high rod density, high
rod stiffness, and/or low line tension of the membrane edge, the rod assembly
induces vesicle rupture, resulting in the formation of a high-genus vesicle. A
gradual change in the curvature suppresses this rupture. Hence, large stress,
compared to the edge tension, induced by the rod assembly is the key factor
determining rupture. For rod curvature with the opposite sign to the vesicle
curvature, membrane rupture induces inversion of the membrane, leading to
division into multiple vesicles as well as formation of a high-genus vesicle.


title: KPZ equation with fractional derivatives of white noise

abstract:
  In this paper, we consider the KPZ equation driven by space-time white noise
replaced with its fractional derivatives of order $\gamma>0$ in spatial
variable. A well-posedness theory for the KPZ equation is established by Hairer
[3] as an application of the theory of regularity structures. Our aim is to see
to what extent his theory works if noises become rougher. We can expect that
his theory works if and only if $\gamma<1/2$. However, we show that the
renormalization like "$(\partial_x h)^2-\infty$" is well-posed only if
$\gamma<1/4$.


title:
On Lipschitz solutions for some forward-backward parabolic equations.
  II: The case against Fourier

abstract:
  As a sequel to the paper [9], we study the existence and properties of
Lipschitz solutions to the initial-boundary value problem of some
forward-backward parabolic equations with diffusion fluxes violating Fourier's
inequality.


title: Personalized Expertise Search at LinkedIn

abstract:
  LinkedIn is the largest professional network with more than 350 million
members. As the member base increases, searching for experts becomes more and
more challenging. In this paper, we propose an approach to address the problem
of personalized expertise search on LinkedIn, particularly for exploratory
search queries containing {\it skills}. In the offline phase, we introduce a
collaborative filtering approach based on matrix factorization. Our approach
estimates expertise scores for both the skills that members list on their
profiles as well as the skills they are likely to have but do not explicitly
list. In the online phase (at query time) we use expertise scores on these
skills as a feature in combination with other features to rank the results. To
learn the personalized ranking function, we propose a heuristic to extract
training data from search logs while handling position and sample selection
biases. We tested our models on two products - LinkedIn homepage and LinkedIn
recruiter. A/B tests showed significant improvements in click through rates -
31% for CTR@1 for recruiter (18% for homepage) as well as downstream messages
sent from search - 37% for recruiter (20% for homepage). As of writing this
paper, these models serve nearly all live traffic for skills search on LinkedIn
homepage as well as LinkedIn recruiter.


title:
A higher order Painlev\'e system in two variables and extensions of the
  Appell hypergeometric functions $F_1$, $F_2$ and $F_3$

abstract:
  In this article we propose an extension of Appell hypergeometric function
$F_2$ (or equivalently $F_3$). It is derived from a particular solution of a
higher order Painlev\'e system in two variables. On the other hand, an
extension of Appell's $F_1$ was introduced by Tsuda. We also show that those
two extensions are equivalent at the level of systems of linear partial
differential equations.


title:
Multispecies totally asymmetric zero range process: II. Hat relation and
  tetrahedron equation

abstract:
  We consider a three-dimensional (3D) lattice model associated with the
intertwiner of the quantized coordinate ring $A_q(sl_3)$, and introduce a
family of layer to layer transfer matrices on $m\times n$ square lattice. By
using the tetrahedron equation we derive their commutativity and bilinear
relations mixing various boundary conditions. At $q=0$ and $m=n$, they lead to
a new proof of the steady state probability of the $n$-species totally
asymmetric zero range process obtained recently by the authors, revealing the
3D integrability in the matrix product construction.


abstract:
  A reciprocal transformation for a 3-component Camassa-Holm type system is
constructed to connect it with the first negative flow of a generalized MKdV
hierarchy, and a bi-Hamiltonian structure for the transformed system is also
considered.


title: Once punctured disks, non-convex polygons, and pointihedra

abstract:
  We explore several families of flip-graphs, all related to polygons or
punctured polygons. In particular, we consider the topological flip-graphs of
once-punctured polygons which, in turn, contain all possible geometric
flip-graphs of polygons with a marked point as embedded sub-graphs. Our main
focus is on the geometric properties of these graphs and how they relate to one
another. In particular, we show that the embeddings between them are strongly
convex (or, said otherwise, totally geodesic). We also find bounds on the
diameters of these graphs, sometimes using the strongly convex embeddings.
Finally, we show how these graphs relate to different polytopes, namely type D
associahedra and a family of secondary polytopes which we call pointihedra.


title:
Relations Between Conditional Shannon Entropy and Expectation of
  $\ell_{\alpha}$-Norm

abstract:
  The paper examines relationships between the conditional Shannon entropy and
the expectation of $\ell_{\alpha}$-norm for joint probability distributions.
More precisely, we investigate the tight bounds of the expectation of
$\ell_{\alpha}$-norm with a fixed conditional Shannon entropy, and vice versa.
As applications of the results, we derive the tight bounds between the
conditional Shannon entropy and several information measures which are
determined by the expectation of $\ell_{\alpha}$-norm, e.g., the conditional
R\'{e}nyi entropy and the conditional $R$-norm information. Moreover, we apply
these results to discrete memoryless channels under a uniform input
distribution. Then, we show the tight bounds of Gallager's $E_{0}$ functions
with a fixed mutual information under a uniform input distribution.


title: PHENIX results on Bose-Einstein correlation functions

abstract:
  Measurement of Bose-Einstein or HBT correlations of identified charged
particles provide insight into the space-time structure of particle emitting
sources in heavy-ion collisions. In this paper we present the latest results
from the RHIC PHENIX experiment on such measurements.


title:
Secure Approximation Guarantee for Cryptographically Private Empirical
  Risk Minimization

abstract:
  Privacy concern has been increasingly important in many machine learning (ML)
problems. We study empirical risk minimization (ERM) problems under secure
multi-party computation (MPC) frameworks. Main technical tools for MPC have
been developed based on cryptography. One of limitations in current
cryptographically private ML is that it is computationally intractable to
evaluate non-linear functions such as logarithmic functions or exponential
functions. Therefore, for a class of ERM problems such as logistic regression
in which non-linear function evaluations are required, one can only obtain
approximate solutions. In this paper, we introduce a novel cryptographically
private tool called secure approximation guarantee (SAG) method. The key
property of SAG method is that, given an arbitrary approximate solution, it can
provide a non-probabilistic assumption-free bound on the approximation quality
under cryptographically secure computation framework. We demonstrate the
benefit of the SAG method by applying it to several problems including a
practical privacy-preserving data analysis task on genomic and clinical
information.


title: Ruin under stochastic dependence between premium and claim arrivals

abstract:
  We investigate, focusing on the ruin probability, an adaptation of the
Cramer-Lundberg model for the surplus process of an insurance company, in
which, conditionally on their intensities, the two mixed Poisson processes
governing the arrival times of the premiums and of the claims respectively, are
independent. Such a model exhibits a stochastic dependence between the
aggregate premium and claim amount processes. An explicit expression for the
ruin probability is obtained when the claim and premium sizes are exponentially
distributed.


title: On Minimum Maximal Distance-k Matchings

abstract:
  We study the computational complexity of several problems connected with
finding a maximal distance-$k$ matching of minimum cardinality or minimum
weight in a given graph. We introduce the class of $k$-equimatchable graphs
which is an edge analogue of $k$-equipackable graphs. We prove that the
recognition of $k$-equimatchable graphs is co-NP-complete for any fixed $k \ge
2$. We provide a simple characterization for the class of strongly chordal
graphs with equal $k$-packing and $k$-domination numbers. We also prove that
for any fixed integer $\ell \ge 1$ the problem of finding a minimum weight
maximal distance-$2\ell$ matching and the problem of finding a minimum weight
$(2 \ell - 1)$-independent dominating set cannot be approximated in polynomial
time in chordal graphs within a factor of $\delta \ln |V(G)|$ unless
$\mathrm{P} = \mathrm{NP}$, where $\delta$ is a fixed constant (thereby
improving the NP-hardness result of Chang for the independent domination case).
Finally, we show the NP-hardness of the minimum maximal induced matching and
independent dominating set problems in large-girth planar graphs.


title: Spectral atlas of two peculiar supergiants: MWC314 and IRC+10420

abstract:
  An atlas of spectra of the unique high luminosity objects MWC 314 and
IRC+10420 taken with the CCD echelle spectrograph (R=15000) at the prime focus
of the 6-m telescope of SAO is presented. About 320 emission and absorption
features of stellar, circumstellar and interstellar nature are identified in
the interval between 4790 and 7520 \AA{}. Their relative intensities and radial
velocities are given and the distinctions of their profiles are discussed.


title: On the construction of semisimple Lie algebras and Chevalley groups

abstract:
  Let $\mathfrak{g}$ be a semisimple complex Lie algebra. Recently, Lusztig
simplified the traditional construction of the corresponding Chevalley groups
(of adjoint type) using the "canonical basis" of the adjoint representation
of~$\mathfrak{g}$. Here, we present a variation of this idea which leads to a
new, and quite elementary construction of~$\mathfrak{g}$ itself from its root
system. An additional feature of this set-up is that it also gives rise to
explicit Chevalley bases of $\mathfrak{g}$.


title: Weyl Spreading Sequence Optimizing CDMA

abstract:
  This paper shows an optimal spreading sequence in the Weyl sequence class,
which is similar to the set of the Oppermann sequences for asynchronous CDMA
systems. Sequences in Weyl sequence class have the desired property that the
order of cross-correlation is low. Therefore, sequences in the Weyl sequence
class are expected to minimize the inter-symbol interference. We evaluate the
upper bound of cross-correlation and odd cross-correlation of spreading
sequences in the Weyl sequence class and construct the optimization problem:
minimize the upper bound of the absolute values of cross-correlation and odd
cross-correlation. Since our optimization problem is convex, we can derive the
optimal spreading sequences as the global solution of the problem. We show
their signal to interference plus noise ratio (SINR) in a special case. From
this result, we propose how the initial elements are assigned, that is, how
spreading sequences are assigned to each users. In an asynchronous CDMA system,
we also numerically compare our spreading sequences with other ones, the Gold
codes, the Oppermann sequences, the optimal Chebyshev spreading sequences and
the SP sequences in Bit Error Rate. Our spreading sequence, which yields the
global solution, has the highest performance among the other spreading
sequences tested.


title:
Extremal function for Moser-Trudinger type Inequality with Logarithmic
  weight

abstract:
  On the space of weighted radial Sobolev space, the following generalization
of Moser-Trudinger type inequality was established by Calanchi and Ruf in
dimension 2 : If $\beta \in [0,1)$ and $w_0(x) = |\log |x||^\beta $ then $$
\sup_{\int_B |\grad u|^2w_0 \leq 1 , u \in H_{0,rad}^1(w_0,B)} \int_B e^{\alpha
u^{\frac{2}{1-\beta}}} dx < \infty,$$ if and only if $\alpha \leq \alpha_\beta
= 2\left[2\pi (1-\beta) \right]^{\frac{1}{1-\beta}}.$ We prove the existence of
an extremal function for the above inequality for the critical case when
$\alpha = \alpha_\beta$ thereby generalizing the result of Carleson-Chang who
proved the case when $\beta =0$.


title: Average chain transitivity and the almost average shadowing property

abstract:
  In this paper, we introduce and study notions of average chain transitivity,
average chain mixing, total average chain transitivity and almost average
shadowing property. We also discuss their interrelations.


title:
Shear to longitudinal mode conversion via second harmonic generation in
  a two-dimensional microscale granular crystal

abstract:
  Shear to longitudinal mode conversion via second harmonic generation is
studied theoretically and computationally for plane waves in a two-dimensional,
adhesive, hexagonally close-packed microscale granular medium. The model
includes translational and rotational degrees of freedom, as well as normal and
shear contact interactions. We consider fundamental frequency plane waves in
all three linear modes, which have infinite spatial extent and travel in one of
the high-symmetry crystal directions. The generated second harmonic waves are
longitudinal for all cases. For the lower transverse-rotational mode, an
analytical expression for the second harmonic amplitude, which is derived using
a successive approximations approach, reveals the presence of particular
resonant and antiresonant wave numbers, the latter of which is prohibited if
rotations are not included in the model. By simulating a lattice with adhesive
contact force laws, we study the effectiveness of the theoretical analysis for
non-resonant, resonant, and antiresonant cases. This work is suitable for the
analysis of microscale and statically compressed macroscale granular media, and
should inspire future studies on nonlinear two- and three-dimensional granular
systems in which interparticle shear coupling and particle rotations play a
significant role.


title:
Isomorphic quartic K3 surfaces in the view of Cremona and projective
  transformations

abstract:
  We show that there is a pair of smooth complex quartic K3 surfaces $S_1$ and
$S_2$ in ${\mathbf P}^3$ such that $S_1$ and $S_2$ are isomorphic as abstract
varieties but not Cremona isomorphic. We also show, in a geometrically explicit
way, that there is a pair of smooth complex quartic K3 surfaces $S_1$ and $S_2$
in ${\mathbf P}^3$ such that $S_1$ and $S_2$ are Cremona isomorphic, but not
projectively isomorphic. This work is much motivated by several e-mails from
Professors Tuyen Truong and J\'anos Koll\'ar.


title: Optimal Best Arm Identification with Fixed Confidence

abstract:
  We give a complete characterization of the complexity of best-arm
identification in one-parameter bandit problems. We prove a new, tight lower
bound on the sample complexity. We propose the `Track-and-Stop' strategy, which
we prove to be asymptotically optimal. It consists in a new sampling rule
(which tracks the optimal proportions of arm draws highlighted by the lower
bound) and in a stopping rule named after Chernoff, for which we give a new
analysis.


title:
Electrical Switching of Magnetization in Films of alpha-Iron with
  Naturally Hydroxidized Surface

abstract:
  Control of the magnetization vector in ferromagnetic films and
heterostructures by using electric tools instead of external magnetic fields
can lead to low-power memory devices. We observe the robust changes in
magnetization states of a thin (about 30 nm) film of alpha-Fe covered by the
naturally formed layer ( about 6 nm in thickness) of iron ohyhydroxides (FeOOH)
under discharging a capacitor through the film. Strikingly, the magnetization
vector is switchable by the discharge even with no any biasing field at room
temperatures. In this electrically induced magnetization switching (EIMS) we
reveal the key role of the FeOOH layer. We demonstrate experimental evidences
that not the discharge current itself but the electric field (of the order of
10 kV/m) generated by this current is responsible for EIMS. The results
reported here provide a plausible explanation of the observed phenomenon in
terms of electric-field-induced weak ferromagnetism in the FeOOH layer and its
coupling with the underlying alpha-Fe.


title: ARQ with Adaptive Feedback for Energy Harvesting Receivers

abstract:
  Automatic repeat request (ARQ) is widely used in modern communication systems
to improve transmission reliability. In conventional ARQ protocols developed
for systems with energy-unconstrained receivers, an
acknowledgement/negative-acknowledgement (ACK/NACK) message is fed back when
decoding succeeds/fails. Such kind of non-adaptive feedback consumes
significant amount of energy, and thus will limit the performance of systems
with energy harvesting (EH) receivers. In order to overcome this limitation and
to utilize the harvested energy more efficiently, we propose a novel ARQ
protocol for EH receivers, where the ACK feedback can be adapted based upon the
receiver's EH state. Two conventional ARQ protocols are also considered. By
adopting the packet drop probability (PDP) as the performance metric, we
formulate the throughput constrained PDP minimization problem for a
communication link with a non-EH transmitter and an EH receiver. Optimal
reception policies including the sampling, decoding and feedback strategies,
are developed for different ARQ protocols. Simulation results will show that
the proposed ARQ protocol not only outperforms the conventional ARQs in terms
of PDP, but can also achieve a higher throughput.


title: Implementation of bipartite or remote unitary gates with repeater nodes

abstract:
  We propose some protocols to implement various classes of bipartite unitary
operations on two remote parties with the help of repeater nodes in-between. We
also present a protocol to implement a single-qubit unitary with parameters
determined by a remote party with the help of up to three repeater nodes. It is
assumed that the neighboring nodes are connected by noisy photonic channels,
and the local gates can be performed quite accurately, while the decoherence of
memories is significant. A unitary is often a part of a larger computation or
communication task in a quantum network, and to reduce the amount of
decoherence in other systems of the network, we focus on the goal of saving the
total time for implementing a unitary including the time for entanglement
preparation. We review some previously studied protocols that implement
bipartite unitaries using local operations and classical communication and
prior shared entanglement, and apply them to the situation with repeater nodes
without prior entanglement. We find that the protocols using piecewise
entanglement between neighboring nodes often require less total time compared
to preparing entanglement between the two end nodes first and then performing
the previously known protocols. For a generic bipartite unitary, as the number
of repeater nodes increases, the total time could approach the time cost for
direct signal transfer from one end node to the other. We also prove some lower
bounds of the total time when there are a small number of repeater nodes. The
application to position-based cryptography is discussed.


title: Edge Detection for Pattern Recognition: A Survey

abstract:
  This review provides an overview of the literature on the edge detection
methods for pattern recognition that inspire from the understanding of human
vision. We note that edge detection is one of the most fundamental process
within the low level vision and provides the basis for the higher level visual
intelligence in primates. The recognition of the patterns within the images
relate closely to the spatiotemporal processes of edge formations, and its
implementation needs a crossdisciplanry approach in neuroscience, computing and
pattern recognition. In this review, the edge detectors are grouped in as edge
features, gradients and sketch models, and some example applications are
provided for reference. We note a significant increase in the amount of
published research in the last decade that utilizes edge features in a wide
range of problems in computer vision and image understanding having a direct
implication to pattern recognition with images.


title:
Dunkl harmonic analysis and fundamental sets of continuous functions on
  the unit sphere

abstract:
  We establish a necessary and sufficient condition on a continuous function on
$[-1,1]$ under which the family of functions on the unit sphere
$\mathbb{S}^{d-1}$ constructed in the described manner is fundamental in
$C(\mathbb{S}^{d-1})$. In our construction of functions and proof of the
result, we essentially use Dunkl harmonic analysis.


title:
Many flavor approach to study the nature of chiral phase transition of
  two-flavor QCD

abstract:
  We perform lattice numerical simulations to study the phase transition of QCD
at finite temperature to clarify the nature of the transition of massless two
flavor QCD. We investigate QCD with two light and Nf heavy quarks instead of
two-flavor QCD, and focus on the light quark mass dependence of the critical
heavy mass, below which the transition is of first order. The heavy quarks are
incorporated into two flavor configurations in the form of the hopping
parameter expansion through the reweighting technique. The nature of the
transition is identified by the shape of the constraint effective potential at
the critical temperature. Our result indicates that the critical heavy mass
remains finite in the chiral limit of the two flavors, suggesting the phase
transition of massless two-flavor QCD is of second order.


title:
Rotation Measure synthesis study and polarized properties of PSR
  J1745-2900 at 7 mm

abstract:
  We present results of interferometric polarization observations of the
recently discovered magnetar J1745-2900 in the vicinity of the Galactic center.
The observations were made with the Karl G. Jansky Very Large Array (VLA) on 21
February 2014 in the range 40-48 GHz. The full polarization mode and A
configuration of the array were used. The average total and linearly polarized
flux density of the pulsar amounts to 2.3$\pm$0.31 mJy/beam and 1.5$\pm$0.2
mJy/beam, respectively. Analysis shows a rotation measure (RM) of
(-67$\pm$3)x10$^3$ rad/m$^2$, which is in a good agreement with previous
measurements at longer wavelengths. These high frequency observations are
sensitive to RM values of up to ~2x10$^7$ rad/m$^2$. However, application of
the Faraday RM synthesis technique did not reveal other significant RM
components in the pulsar emission. This supports an external nature of a single
thin Faraday-rotating screen which should be located close to the Galactic
center. The Faraday corrected intrinsic electric vector position angle is
16$\pm$9 deg East of North, and coincides with the position angle of the
pulsar's transverse velocity. All measurements of the pulsar's RM value to
date, including the one presented here, well agree within errors, which points
towards a steady nature of the Faraday-rotating medium.


title: Eigenvalues under the Ricci flow of model geometries

abstract:
  In this paper, we study the evolving behaviors of the first eigenvalue of
Laplace-Beltrami operator under the normalized Ricci flow of model geometries.
In every Bianchi class, we estimate the derivative of the eigenvalue. Then we
construct monotonic quantities under the Ricci flow and obtain upper and lower
bounds for the eigenvalue.


title: Bondi accretion in early-type galaxies

abstract:
  Accretion onto central massive black holes in galaxies is often modelled with
the Bondi solution. In this paper we study a generalization of the classical
Bondi accretion theory, considering the additional effects of the gravitational
potential of the host galaxy, and of electron scattering in the optically thin
limit. We provide a general analysis of the bias in the estimates of the Bondi
radius and mass accretion rate, when adopting as fiducial values for the
density and temperature at infinity the values of these quantities measured at
finite distance from the central black hole. We also give general formulae to
compute the correction terms of the critical accretion parameter in relevant
asymptotic regimes. A full analytical discussion is presented in the case of an
Hernquist galaxy, when the problem reduces to the discussion of a cubic
equation, therefore allowing for more than one critical point in the accretion
structure. The results are useful for observational works (especially in the
case of low-luminosity systems), as well as for numerical simulations, where
accretion rates are usually defined in terms of the gas properties near the


title: On topological actions of finite, non-standard groups on spheres

abstract:
  The standard actions of finite groups on spheres S^d are linear actions, i.e.
by finite subgroups of the orthogonal group O(d+1). We prove that, in each
dimension d>5, there is a finite group G which admits a faithful, topological
action on a sphere S^d but is not isomorphic to a subgroup of O(d+1). The
situation remains open for smooth actions.


title:
The anatomy of a long gamma-ray burst: a simple classification scheme
  for the emission mechanism(s)

abstract:
  Ultra-relativistic motion and efficient conversion of kinetic energy to
radiation are required by gamma-ray burst (GRB) observations, yet they are
difficult to simultaneously achieve. Three leading mechanisms have been
proposed to explain the observed emission emanating from GRB outflows:
radiation from either relativistic internal or external shocks, or thermal
emission from a photosphere. Previous works were dedicated to independently
treating these three mechanisms and arguing for a sole, unique origin of the
prompt emission of gamma-ray bursts. In contrast, herein, we first explain why
all three models are valid mechanisms and that a contribution from each of them
is expected in the prompt phase. Additionally, we show that a single parameter,
the dimensionless entropy of the GRB outflow, determines which mechanism
contributes the most to the emission. More specifically, internal shocks
dominate for low values of the dimensionless entropy, external shocks for
intermediate values and finally, photospheric emission for large values. We
present a unified framework for the emission mechanisms of GRBs with easily
testable predictions for each process.


title:
Selective Inference Approach for Statistically Sound Predictive Pattern
  Mining

abstract:
  Discovering statistically significant patterns from databases is an important
challenging problem. The main obstacle of this problem is in the difficulty of
taking into account the selection bias, i.e., the bias arising from the fact
that patterns are selected from extremely large number of candidates in
databases. In this paper, we introduce a new approach for predictive pattern
mining problems that can address the selection bias issue. Our approach is
built on a recently popularized statistical inference framework called
selective inference. In selective inference, statistical inferences (such as
statistical hypothesis testing) are conducted based on sampling distributions
conditional on a selection event. If the selection event is characterized in a
tractable way, statistical inferences can be made without minding selection
bias issue. However, in pattern mining problems, it is difficult to
characterize the entire selection process of mining algorithms. Our main
contribution in this paper is to solve this challenging problem for a class of
predictive pattern mining problems by introducing a novel algorithmic
framework. We demonstrate that our approach is useful for finding statistically
significant patterns from databases.