title:
Isothermal compressibility determination across Bose-Einstein
  condensation

abstract:
  We apply the global thermodynamic variables approach to experimentally
determine the isothermal compressibility parameter $\kappa_T$ of a trapped Bose
gas across the phase transition. We demonstrate the behavior of $\kappa_T$
around the critical pressure, revealing the second order nature of the phase
transition. Compressibility is the most important susceptibility to
characterize the system. The use of global variables shows advantages with
respect to the usual local density approximation method and can be applied to a
broad range of situations.


title: On a connection between nonstationary and periodic wavelets

abstract:
  We compare frameworks of nonstationary nonperiodic wavelets and periodic
wavelets. We construct one system from another using periodization. There are
infinitely many nonstationary systems corresponding to the same periodic
wavelet. Under mild conditions on periodic scaling functions, among these
nonstationary wavelet systems, we find a system such that its time-frequency
localization is adjusted with an angular-frequency localization of an initial
periodic wavelet system. Namely, we get the following equality $ \lim_{j\to
\infty} UC_B(\psi^P_j) = \lim_{j\to \infty}UC_H(\psi^N_j), $ where $UC_B$ and
$UC_H$ are the Breitenberger and the Heisenberg uncertainty constants,
$\psi^P_j \in L_2(\mathbb{T})$ and $\psi^N_j\in L_2(\mathbb{R})$ are periodic
and nonstationary wavelet functions respectively.


title:
Phase Noise Influence in Coherent Optical OFDM Systems with RF Pilot
  Tone: Digital IFFT Multiplexing and FFT Demodulation

abstract:
  We present a comparative study of the influence of dispersion induced phase
noise for CO-OFDM systems using Tx channel multiplexing and Rx matched filter
(analogue hardware based); and FFT multiplexing/IFFT demultiplexing techniques
(software based). An RF carrier pilot tone is used to mitigate the phase noise
influence. From the analysis, it appears that the phase noise influence for the
two OFDM implementations is very similar. The software based system provides a
method for a rigorous evaluation of the phase noise variance caused by Common
Phase Error (CPE) and Inter-Carrier Interference (ICI) and this, in turns,
leads to a BER specification. Numerical results focus on a CO-OFDM system with
1GS/s QPSK channel modulation. Worst case BER results are evaluated and
compared to the BER of a QPSK system with the same capacity as the OFDM
implementation. Results are evaluated as a function of transmission distance,
and for the QPSK system the influence of equalization enhanced phase noise
(EEPN) is included. For both types of systems, the phase noise variance
increases significantly with increasing transmission distance. An important and
novel observation is that the two types of systems have very closely the same
BER as a function of transmission distance for the same capacity. For the high
capacity QPSK implementation, the increase in BER is due to EEPN, whereas for
the OFDM approach it is due to the dispersion caused walk-off of the RF pilot
tone relative to the OFDM signal channels. For a total capacity of 400 Gb/s,
the transmission distance to have the BER < 10-4 is less than 277 km.


title: Electronic Properties of Cyclacenes from TAO-DFT

abstract:
  Owing to the presence of strong static correlation effects, accurate
prediction of the electronic properties (e.g., the singlet-triplet energy gaps,
vertical ionization potentials, vertical electron affinities, fundamental gaps,
symmetrized von Neumann entropy, active orbital occupation numbers, and
real-space representation of active orbitals) of cyclacenes with n fused
benzene rings (n = 4-100) has posed a great challenge to traditional electronic
structure methods. To meet the challenge, we study these properties using our
newly developed thermally-assisted-occupation density functional theory
(TAO-DFT), a very efficient method for the study of large systems with strong
static correlation effects. Besides, to examine the role of cyclic topology,
the electronic properties of cyclacenes are also compared with those of acenes.
Similar to acenes, the ground states of cyclacenes are singlets for all the
cases studied. In contrast to acenes, the electronic properties of cyclacenes,
however, exhibit oscillatory behavior (for n <= 30) in the approach to the
corresponding properties of acenes with increasing number of benzene rings. On
the basis of the calculated orbitals and their occupation numbers, the larger
cyclacenes are shown to exhibit increasing polyradical character in their
ground states, with the active orbitals being mainly localized at the
peripheral carbon atoms.


title: The long-term scientific benefits of a space economy

abstract:
  Utilisation of the material and energy resources of the Solar System will be
essential for the development of a sustainable space economy and associated
infrastructure. Science will be a major beneficiary of a space economy, even if
its major elements (e.g. space tourism, resource extraction activities on the
Moon or asteroids, and large-scale in-space construction capabilities) are not
developed with science primarily in mind. Examples of scientific activities
that would be facilitated by the development of space infrastructure include
the construction of large space telescopes, ambitious space missions (including
human missions) to the outer Solar System, and the establishment of scientific
research stations on the Moon and Mars (and perhaps elsewhere). In the more
distant future, an important scientific application of a well-developed space
infrastructure may be the construction of interstellar space probes for the
exploration of planets around nearby stars.


title:
Structure and enumeration theorems for hereditary properties in finite
  relational languages

abstract:
  Given a finite relational language $\calL$, a hereditary $\calL$-property is
a class of finite $\calL$-structures which is closed under isomorphism and
model theoretic substructure. This notion encompasses many objects of study in
extremal combinatorics, including (but not limited to) hereditary properties of
graphs, hypergraphs, and oriented graphs. In this paper, we generalize certain
definitions, tools, and results form the study of hereditary properties in
combinatorics to the setting of hereditary $\calL$-properties, where $\calL$ is
any finite relational language with maximum arity at least two. In particular,
the goal of this paper is to generalize how extremal results and stability
theorems can be combined with standard techniques and tools to yield
approximate enumeration and structure theorems. We accomplish this by
generalizing the notions of extremal graphs, asymptotic density, and graph
stability theorems using structures in an auxiliary language associated to a
hereditary $\calL$-property. Given a hereditary $\calL$-property $\calH$, we
prove an approximate asymptotic enumeration theorem for $\calH$ in terms of its
generalized asymptotic density. Further we prove an approximate structure
theorem for $\calH$, under the assumption of that $\calH$ has a stability
theorem. The tools we use include a new application of the hypergraph
containers theorem (Balogh-Morris-Samotij, Saxton-Thomason) to the setting of
$\calL$-structures, a general supersaturation theorem for hereditary
$\calL$-properties (also new), and a general graph removal lemma for
$\calL$-structures proved by Aroskar and Cummings.


title: Learning Unitary Operators with Help From u(n)

abstract:
  A major challenge in the training of recurrent neural networks is the
so-called vanishing or exploding gradient problem. The use of a norm-preserving
transition operator can address this issue, but parametrization is challenging.
In this work we focus on unitary operators and describe a parametrization using
the Lie algebra $\mathfrak{u}(n)$ associated with the Lie group $U(n)$ of $n
\times n$ unitary matrices. The exponential map provides a correspondence
between these spaces, and allows us to define a unitary matrix using $n^2$ real
coefficients relative to a basis of the Lie algebra. The parametrization is
closed under additive updates of these coefficients, and thus provides a simple
space in which to do gradient descent. We demonstrate the effectiveness of this
parametrization on the problem of learning arbitrary unitary operators,
comparing to several baselines and outperforming a recently-proposed
lower-dimensional parametrization. We additionally use our parametrization to
generalize a recently-proposed unitary recurrent neural network to arbitrary
unitary matrices, using it to solve standard long-memory tasks.


title: On the consistency of local and global versions of Chang's Conjecture

abstract:
  We show that for many pairs of infinite cardinals $\kappa > \mu^+ > \mu$,
$(\kappa^{+}, \kappa)\twoheadrightarrow (\mu^+, \mu)$ is consistent relative to
the consistency of a supercompact cardinal. We also show that it is consistent,
relative to a huge cardinal that $(\kappa^{+}, \kappa)\twoheadrightarrow
(\mu^+, \mu)$ for every successor cardinal $\kappa$ and every $\mu < \kappa$,
answering a question of Foreman.


title:
Influence of Pre- and Post-compensation of Chromatic Dispersion on
  Equalization Enhanced Phase Noise in Coherent Multilevel Systems

abstract:
  In this paper we present a comparative study in order to specify the
influence of equalization enhanced phase noise (EEPN) for pre- and
post-compensation of chromatic dispersion in high capacity and high
constellation systems. This is - to our knowledge - the first detailed study in
this area for pre-compensation systems. Our main results show that the local
oscillator phase noise determines the EEPN influence in post-compensation
implementations whereas the transmitter laser determines the EEPN in
pre-compensation implementations. As a result of significance for the
implementation of practical longer-range systems it is to be emphasized that
the use of chromatic dispersion equalization in the optical domain - e.g. by
the use of dispersion compensation fibers - eliminates the EEPN entirely. Thus,
this seems a good option for such systems operating at high constellations in
the future.


title: The Interaction of the Fermi Bubbles with the Milky Way's Hot Gas Halo

abstract:
  The Fermi bubbles are two lobes filled with non-thermal particles that emit
gamma rays, extend $\approx$10 kpc vertically from the Galactic center, and
formed from either nuclear star formation or accretion activity on Sgr A*.
Simulations predict a range of shock strengths as the bubbles expand into the
surrounding hot gas halo distribution ($T_{halo} \approx 2 \times 10^6$ K), but
with significant uncertainties in the energetics, age, and thermal gas
structure. The bubbles should contain thermal gas with temperatures between
$10^6$ and $10^8$ K, with potential X-ray signatures. In this work, we
constrain the bubbles' thermal gas structure by modeling the OVII and OVIII
emission line strengths from archival XMM-Newton and Suzaku data. Our emission
model includes a hot thermal volume-filled bubble component cospatial with the
gamma-ray region, and a shell of compressed material. We find that a
bubble/shell model with $n \approx 1 \times 10^{-3}$ cm$^{-3}$ and with
log($T$) $\approx$ 6.60-6.70 is consistent with the observed line intensities.
In the framework of a continuous Galactic outflow, we infer a bubble expansion
rate, age, and energy injection rate of $490_{-77}^{+230}$ km s$^{-1}$,
$4.3_{-1.4}^{+0.8}$ Myr, and $2.3_{-0.9}^{+5.1} \times 10^{42}$ erg s$^{-1}$.
These estimates are consistent with the bubbles forming from a Sgr A* accretion
event rather than from nuclear star formation.


title: Motion Imitation Based on Sparsely Sampled Correspondence

abstract:
  Existing techniques for motion imitation often suffer a certain level of
latency due to their computational overhead or a large set of correspondence
samples to search. To achieve real-time imitation with small latency, we
present a framework in this paper to reconstruct motion on humanoids based on
sparsely sampled correspondence. The imitation problem is formulated as finding
the projection of a point from the configuration space of a human's poses into
the configuration space of a humanoid. An optimal projection is defined as the
one that minimizes a back-projected deviation among a group of candidates,
which can be determined in a very efficient way. Benefited from this
formulation, effective projections can be obtained by using sparse
correspondence. Methods for generating these sparse correspondence samples have
also been introduced. Our method is evaluated by applying the human's motion
captured by a RGB-D sensor to a humanoid in real-time. Continuous motion can be
realized and used in the example application of tele-operation.


title: On the likelihood of normalisation in combinatory logic

abstract:
  We present a quantitative basis-independent analysis of combinatory logic.
Using a general argument regarding plane binary trees with labelled leaves, we
generalise the results of David et al. and Bendkowski et al. to all
Turing-complete combinator bases proving, inter alia, that asymptotically
almost no combinator is strongly normalising nor typeable. We exploit the
structure of recently discovered normal-order reduction grammars showing that
for each positive $n$, the set of $\mathbf{S} \mathbf{K}$-combinators reducing
in $n$ normal-order reduction steps has positive asymptotic density in the set
of all combinators. Our approach is constructive, allowing us to systematically
find new asymptotically significant fractions of normalising combinators. We
show that the density of normalising combinators cannot be less than $34\%$,
improving the previously best lower bound of approximately $3\%$. Finally, we
present some super-computer experimental results, conjecturing that the density
of normalising combinators is close to $85\%$.


title: Fully Dynamic de Bruijn Graphs

abstract:
  We present a space- and time-efficient fully dynamic implementation de Bruijn
graphs, which can also support fixed-length jumbled pattern matching.


title: FO-definable transformations of infinite strings

abstract:
  The theory of regular and aperiodic transformations of finite strings has
recently received a lot of interest. These classes can be equivalently defined
using logic (Monadic second-order logic and first-order logic), two-way
machines (regular two-way and aperiodic two-way transducers), and one-way
register machines (regular streaming string and aperiodic streaming string
transducers). These classes are known to be closed under operations such as
sequential composition and regular (star-free) choice; and problems such as
functional equivalence and type checking, are decidable for these classes. On
the other hand, for infinite strings these results are only known for
$\omega$-regular transformations: Alur, Filiot, and Trivedi studied
transformations of infinite strings and introduced an extension of streaming
string transducers over $\omega$-strings and showed that they capture monadic
second-order definable transformations for infinite strings. In this paper we
extend their work to recover connection for infinite strings among first-order
logic definable transformations, aperiodic two-way transducers, and aperiodic
streaming string transducers.


title: Near-Optimal Induced Universal Graphs for Bounded Degree Graphs

abstract:
  A graph $U$ is an induced universal graph for a family $F$ of graphs if every
graph in $F$ is a vertex-induced subgraph of $U$. For the family of all
undirected graphs on $n$ vertices Alstrup, Kaplan, Thorup, and Zwick [STOC
2015] give an induced universal graph with $O\!\left(2^{n/2}\right)$ vertices,
matching a lower bound by Moon [Proc. Glasgow Math. Assoc. 1965].
  Let $k= \lceil D/2 \rceil$. Improving asymptotically on previous results by
Butler [Graphs and Combinatorics 2009] and Esperet, Arnaud and Ochem [IPL
2008], we give an induced universal graph with $O\!\left(\frac{k2^k}{k!}n^k
\right)$ vertices for the family of graphs with $n$ vertices of maximum degree
$D$. For constant $D$, Butler gives a lower bound of
$\Omega\!\left(n^{D/2}\right)$. For an odd constant $D\geq 3$, Esperet et al.
and Alon and Capalbo [SODA 2008] give a graph with
$O\!\left(n^{k-\frac{1}{D}}\right)$ vertices. Using their techniques for any
(including constant) even values of $D$ gives asymptotically worse bounds than
we present.
  For large $D$, i.e. when $D = \Omega\left(\log^3 n\right)$, the previous best
upper bound was ${n\choose\lceil D/2\rceil} n^{O(1)}$ due to Adjiashvili and
Rotbart [ICALP 2014]. We give upper and lower bounds showing that the size is
${\lfloor n/2\rfloor\choose\lfloor D/2
\rfloor}2^{\pm\tilde{O}\left(\sqrt{D}\right)}$. Hence the optimal size is
$2^{\tilde{O}(D)}$ and our construction is within a factor of
$2^{\tilde{O}\left(\sqrt{D}\right)}$ from this. The previous results were
larger by at least a factor of $2^{\Omega(D)}$.
  As a part of the above, proving a conjecture by Esperet et al., we construct
an induced universal graph with $2n-1$ vertices for the family of graphs with
max degree $2$. In addition, we give results for acyclic graphs with max degree
$2$ and cycle graphs. Our results imply the first labeling schemes that for any
$D$ are at most $o(n)$ bits from optimal.


title: Trajectory Fitting Estimators for SPDEs Driven by Additive Noise

abstract:
  In this paper we study the problem of estimating the drift/viscosity
coefficient for a large class of linear, parabolic stochastic partial
differential equations (SPDEs) driven by an additive space-time noise. We
propose a new class of estimators, called trajectory fitting estimators (TFEs).
The estimators are constructed by fitting the observed trajectory with an
artificial one, and can be viewed as an analog to the classical least squares
estimators from the time-series analysis. As in the existing literature on
statistical inference for SPDEs, we take a spectral approach, and assume that
we observe the first $N$ Fourier modes of the solution, and we study the
consistency and the asymptotic normality of the TFE, as $N\to\infty$.


title: An Improved Algorithm for Incremental DFS Tree in Undirected Graphs

abstract:
  Depth first search (DFS) tree is one of the most well-known data structures
for designing efficient graph algorithms. Given an undirected graph $G=(V,E)$
with $n$ vertices and $m$ edges, the textbook algorithm takes $O(n+m)$ time to
construct a DFS tree. In this paper, we study the problem of maintaining a DFS
tree when the graph is undergoing incremental updates. Formally, we show: Given
an arbitrary online sequence of edge or vertex insertions, there is an
algorithm that reports a DFS tree in $O(n)$ worst case time per operation, and
requires $O\left(\min\{m \log n, n^2\}\right)$ preprocessing time.
  Our result improves the previous $O(n \log^3 n)$ worst case update time
algorithm by Baswana et al. and the $O(n \log n)$ time by Nakamura and
Sadakane, and matches the trivial $\Omega(n)$ lower bound when it is required
to explicitly output a DFS tree.
  Our result builds on the framework introduced in the breakthrough work by
Baswana et al., together with a novel use of a tree-partition lemma by Duan and
Zhan, and the celebrated fractional cascading technique by Chazelle and Guibas.


title:
Magnetic field disorder and Faraday effects on the polarization of
  extragalactic radio sources

abstract:
  We present a polarization catalog of 533 extragalactic radio sources with 2.3
GHz total intensity above 420 mJy from the S-band Polarization All Sky Survey,
S-PASS, with corresponding 1.4 GHz polarization information from the NRAO VLA
Sky Survey, NVSS. We studied selection effects and found that fractional
polarization, $\pi$, of radio objects at both wavelengths depends on the
spectral index, source magnetic field disorder, source size and depolarization.
The relationship between depolarization, spectrum and size shows that
depolarization occurs primarily in the source vicinity. The median $\pi_{2.3}$
of resolved objects in NVSS is approximately two times larger than that of
unresolved sources. Sources with little depolarization are $\sim2$ times more
polarized than both highly depolarized and re-polarized sources. This indicates
that intrinsic magnetic field disorder is the dominant mechanism responsible
for the observed low fractional polarization of radio sources at high
frequencies. We predict that number counts from polarization surveys will be
similar at 1.4 GHz and at 2.3 GHz, for fixed sensitivity, although $\sim$10% of
all sources may be currently missing because of strong depolarization. Objects
with $\pi_{1.4}\approx \pi_{2.3} \ge 4\%$ typically have simple Faraday
structures, so are most useful for background samples. Almost half of flat
spectrum ($\alpha \ge -0.5$) and $\sim$25% of steep spectrum objects are
re-polarized. Steep spectrum, depolarized sources show a weak negative
correlation of depolarization with redshift in the range 0 $<$ z $<$ 2.3.
Previous non-detections of redshift evolution are likely due the inclusion of
re-polarized sources as well.


title: Thompson's group F is not strongly amenable

abstract:
  We show that Thompson's group $F$ has a topological action on a compact
metric space that is proximal and has no fixed points.


title:
Enhancing entanglement, local and non-local information of accelerated
  two-qubit and two- qutrit systems via weak-reverse measurements

abstract:
  The possibility of recovering and protecting the entanglement of accelerated
2-qubit and 2-qutrit systems is discussed using weak-reverse measurements. The
accelerated partial entangled states are more responsive to be protected than
the accelerated maximum entangled states. The accelerated coded local
information in qutrit system is more robust than that encoded in a 2-qubit
system, and it can be conserved even for larger values of accelerations.
Meanwhile, the non-accelerated information in qubit system is not affected by
the local operation compared with that depicted on qutrit system. For larger
values of accelerations, the weak-reverse measurements can improve the coherent
information at the expanse of the accelerated information.


title: Piecewise convexity of artificial neural networks

abstract:
  Although artificial neural networks have shown great promise in applications
including computer vision and speech recognition, there remains considerable
practical and theoretical difficulty in optimizing their parameters. The
seemingly unreasonable success of gradient descent methods in minimizing these
non-convex functions remains poorly understood. In this work we offer some
theoretical guarantees for networks with piecewise affine activation functions,
which have in recent years become the norm. We prove three main results.
Firstly, that the network is piecewise convex as a function of the input data.
Secondly, that the network, considered as a function of the parameters in a
single layer, all others held constant, is again piecewise convex. Finally,
that the network as a function of all its parameters is piecewise multi-convex,
a generalization of biconvexity. From here we characterize the local minima and
stationary points of the training objective, showing that they minimize certain
subsets of the parameter space. We then analyze the performance of two
optimization algorithms on multi-convex problems: gradient descent, and a
method which repeatedly solves a number of convex sub-problems. We prove
necessary convergence conditions for the first algorithm and both necessary and
sufficient conditions for the second, after introducing regularization to the
objective. Finally, we remark on the remaining difficulty of the global
optimization problem. Under the squared error objective, we show that by
varying the training data, a single rectifier neuron admits local minima
arbitrarily far apart, both in objective value and parameter space.


title: Rare B-Meson Decays at the Crossroads

abstract:
  Experimental era of rare $B$-decays started with the measurement of $B \to
K^* \gamma$ by CLEO in 1993, followed two years later by the measurement of the
inclusive decay $B \to X_s \gamma$, which serves as the standard candle in this
field. The frontier has moved in the meanwhile to the experiments at the LHC,
in particular, LHCb, with the decay $B^0 \to \mu^+ \mu^-$ at about 1 part in
$10^{10}$ being the smallest branching fraction measured so far. Experimental
precision achieved in this area has put the standard model to unprecedented
stringent tests and more are in the offing in the near future. I review some
key measurements in radiative, semileptonic and leptonic rare $B$-decays,
contrast them with their estimates in the SM, and focus on several mismatches
reported recently. They are too numerous to be ignored, yet , standing alone,
none of them is significant enough to warrant the breakdown of the SM. Rare
$B$-decays find themselves at the crossroads, possibly pointing to new
horizons, but quite likely requiring an improved theoretical description in the
context of the SM. An independent precision experiment such as Belle II may
help greatly in clearing some of the current experimental issues.


title:
OGLE-2016-BLG-0596Lb: High-Mass Planet From High-Magnification
  Pure-Survey Microlensing Event

abstract:
  We report the discovery of a high mass-ratio planet $q=0.012$, i.e., 13 times
higher than the Jupiter/Sun ratio. The host mass is not presently measured but
can be determined or strongly constrained from adaptive optics imaging. The
planet was discovered in a small archival study of high-magnification events in
pure-survey microlensing data, which was unbiased by the presence of anomalies.
The fact that it was previously unnoticed may indicate that more such planets
lie in archival data and could be discovered by similar systematic study. In
order to understand the transition from predominantly survey+followup to
predominately survey-only planet detections, we conduct the first analysis of
these detections in the observational $(s,q)$ plane. Here $s$ is projected
separation in units of the Einstein radius. We find some evidence that
survey+followup is relatively more sensitive to planets near the Einstein ring,
but that there is no statistical difference in sensitivity by mass ratio.


title: On equilibrium shapes of charged flat drops

abstract:
  Equilibrium shapes of two-dimensional charged, perfectly conducting liquid
drops are governed by a geometric variational problem that involves a perimeter
term modeling line tension and a capacitary term modeling Coulombic repulsion.
Here we give a complete explicit solution to this variational problem. Namely,
we show that at fixed total charge a ball of a particular radius is the unique
global minimizer among all sufficiently regular sets in the plane. For sets
whose area is also fixed, we show that balls are the only minimizers if the
charge is less than or equal to a critical charge, while for larger charge
minimizers do not exist. Analogous results hold for drops whose potential,
rather than charge, is fixed.


title:
Single-inclusive jet production in electron-nucleon collisions through
  next-to-next-to-leading order in perturbative QCD

abstract:
  We compute the ${\cal O}(\alpha^2\alpha_s^2)$ perturbative corrections to
inclusive jet production in electron-nucleon collisions. This process is of
particular interest to the physics program of a future Electron Ion Collider
(EIC). We include all relevant partonic processes, including deep-inelastic
scattering contributions, photon-initiated corrections, and parton-parton
scattering terms that first appear at this order. Upon integration over the
final-state hadronic phase space we validate our results for the deep-inelastic
corrections against the known next-to-next-to-leading order (NNLO) structure
functions. Our calculation uses the $N$-jettiness subtraction scheme for
performing higher-order computations, and allows for a completely differential
description of the deep-inelastic scattering process. We describe the
application of this method to inclusive jet production in detail, and present
phenomenological results for the proposed EIC. The NNLO corrections have a
non-trivial dependence on the jet kinematics and arise from an intricate
interplay between all contributing partonic channels.


title:
High-frequency acoustic wave detection in Schottky diodes: theory
  consideration

abstract:
  In this paper the theory of high-frequency acoustic signal detection by
Schottky diodes is presented. Physically, the detection was found to be due to
the quasi-static screening of the potential perturbation caused by the acoustic
strain by charge carriers. The total charge required for screening changes with
the value of strain at the edge of the semiconductor depletion region and
metal-semiconductor interface giving rise to displacement current. The
magnitude and frequency dependence of the electrical signals are analyzed for
both piezoelectric and deformation potential coupling mechanisms. The obtained
results are in good agreement with the recent experimental observations and
suggest feasibility of high-frequency (up to terahertz band) acoustic wave
detection provided that proper electrical measuring scheme is available.


title: Amiable mixed schemes for fourth order curl equations

abstract:
  In this paper, amiable mixed schemes are presented for two variants of fourth
order curl equations. Specifically, mixed formulations for the problems are
constructed, which are well-posed in Babuska-Brezzi's sense and admit stable
discretizations by finite element spaces of low smoothness and of low degree.
The regularities of the mixed formulations and thus equivalently the primal
problems are established, and some finite elements examples are given which can
exploit the regularity of the solutions to an optimal extent.


title: Type-II Weyl Points in Three-Dimensional Cold Atom Optical Lattices

abstract:
  Topological Lifshitz phase transition characterizes an abrupt change of the
topology of the Fermi surface through a continuous deformation of parameters.
Recently, Lifshitz transition has been predicted to separate two types of Weyl
points: type-I and type-II (or called structured Weyl points), which has
attracted considerable attention in various fields. Although recent
experimental investigation has seen a rapid progress on type-II Weyl points, it
still remains a significant challenge to observe their characteristic Lifshitz
transition. Here, we propose a scheme to realize both type-I and type-II Weyl
points in three-dimensional ultracold atomic gases by introducing an
experimentally feasible configuration based on current spin-orbit coupling
technology. In the resultant Hamiltonian, we find three degenerate points: two
Weyl points carrying a Chern number $-1$ and a four-fold degenerate point
carrying a Chern number $2$. Remarkably, by continuous tuning of a convenient
experimental knob, all these degenerate points can transition from type-I to
type-II, thereby providing an ideal platform to study different types of Weyl
points and directly probe their Lifshitz phase transition.


title: Interlayer breathing and shear modes in NbSe2 atomic layers

abstract:
  Atomically thin NbSe2 is a metallic layered transition metal dichalcogenide
(TMD) with considerably different crystallographic structure and electronic
properties from other TMDs, such as MoS2, MoSe2, WS2 and WSe2. Properties of
TMD atomic layers are sensitive to interlayer coupling. Here we investigate the
interlayer phonons of few-layer NbSe2 by ultralow-frequency Raman spectroscopy.
We observe both the interlayer breathing modes and shear modes at frequencies
below 40 cm-1 for samples of 2 to 15 layers. Their frequency, Raman activity,
and environmental instability depend systematically on the layer number. We
account for these results utilizing a combination of the linear-chain model,
group-theory analysis and first-principles calculations. Although NbSe2
possesses different stacking order from MoS2, MoSe2, WS2 and WSe2, it exhibits
the same symmetry and Raman selection rules, as well as similar interlayer
coupling strength and thickness dependence of interlayer phonon modes.


title: Compressed sensing with corrupted Fourier measurements

abstract:
  This paper studies a data recovery problem in compressed sensing (CS), given
a measurement vector b with corruptions: b=Ax0+f0, can we recover x0 and f0 via
the reweighted l1 minimization: minimize |x| + lambda*|f| subject to Ax+f=b?
Here the m by n measurement matrix A is a partial Fourier matrix, x0 denotes
the n dimensional ground true signal vector, f0 denotes the m-dimensional
corrupted noise vector, it is assumed that a positive fraction of entries in
the measurement vector b are corrupted by the non-zero entries of f0. This
problem had been studied in literatures [1-3], unfortunately, certain random
assumptions (which are often hard to meet in practice) are required for the
signal x0 in these papers. In this paper, we show that x0 and f0 can be
recovered exactly by the solution of the above reweighted l1 minimization with
high probability provided that m>O(card(x0)log(n)log(n)) and n is prime, here
card(x0) denotes the cardinality (number of non-zero entries) of x0. Except the
sparsity, no extra assumption is needed for x0.


title: Extremal Problems on Generalized Directed Hypergraphs

abstract:
  In this paper we define a class of combinatorial structures the instances of
which can each be thought of as a model of directed hypergraphs in some way.
Each of these models is uniform in that all edges have the same internal
structure, and each is simple in that no loops or multiedges are allowed. We
generalize the concepts of Turan density, blowup density, and jumps to this
class and show that many basic extremal results extend naturally in this new
setting. In particular, we show that supersaturation holds, the blowup of a
generalized directed hypergraph (GDH) has the same Turan density as the GDH
itself, and degenerate GDHs (those with Turan density zero) can be
characterized as being contained in a blowup of a single edge. Additionally, we
show how the set of jumps from one kind of GDH relates to the set of jumps of
another. Since r-uniform hypergraphs are an instance of the defined class, then
we are able to derive many particular instances of jumps and nonjumps for GDHs
in general based on known results.


title:
Building a Holographic Superconductor with a Scalar Field Coupled
  Kinematically to Einstein Tensor

abstract:
  We study the holographic dual description of a superconductor in which the
gravity sector consists of a Maxwell field and a charged scalar field which
except its minimal coupling to gravity it is also coupled kinematically to
Einstein tensor. As the strength of the new coupling is increased, the critical
temperature below which the scalar field condenses is lowering, the
condensation gap decreases faster than the temperature, the width of the
condensation gap is not proportional to the size of the condensate and at low
temperatures the condensation gap tends to zero for the strong coupling. These
effects which are the result of the presence of the coupling of the scalar
field to the Einstein tensor in the gravity bulk, provide a dual description of
impurities concentration in a superconducting state on the boundary.


title:
Quantum correction to classical gravitational interaction between two
  polarizable objects

abstract:
  When gravity is quantized, there inevitably exist quantum gravitational
vacuum fluctuations which induce quadrupole moments in gravitationally
polarizable objects and produce a quantum correction to the classical Newtonian
interaction between them. Here, based upon linearized quantum gravity and the
leading-order perturbation theory, we study, from a quantum field-theoretic
prospect, this quantum correction between a pair of gravitationally polarizable
objects treated as two-level harmonic oscillators. We find that the interaction
potential behaves like $r^{-11}$ in the retarded regime and $r^{-10}$ in the
near regime. Our result agrees with what was recently obtained in different
approaches. Our study seems to indicate that linearized quantum gravity is
robust in dealing with quantum gravitational effects at low energies.


title:
Extremal Numbers for 2 to 1 Directed Hypergraphs with Two Edges Part I:
  The Nondegenerate Cases

abstract:
  Let a 2 to 1 directed hypergraph be a 3-uniform hypergraph where every edge
has two tail vertices and one head vertex. For any such directed hypergraph F
let the nth extremal number of F be the maximum number of edges that any
directed hypergraph on n vertices can have without containing a copy of F.
There are actually two versions of this problem: the standard version where
every triple of vertices is allowed to have up to all three possible directed
edges and the oriented version where each triple can have at most one directed
edge. In this paper, we determine the standard extremal numbers and the
oriented extremal numbers for three different directed hypergraphs. Each has
exactly two edges, and of the seven (nontrivial) 2 to 1 graphs with exactly two
edges, these are the only three with extremal numbers that are cubic in n. The
standard and oriented extremal numbers for the other four directed hypergraphs
with two edges are determined in a companion paper.


title: Fronthaul-Limited Uplink OFDMA in Ultra-Dense CRAN with Hybrid Decoding

abstract:
  In an ultra-dense cloud radio access network (UD-CRAN), a large number of
remote radio heads (RRHs), typically employed as simple relay nodes, are
distributed in a target area, which could even outnumber their served users.
However, one major challenge is that the large amount of information required
to be transferred between each RRH and the central processor (CP) for joint
signal processing can easily exceed the capacity of the fronthaul links
connecting them. This motivates our study in this paper on a new hybrid
decoding scheme where in addition to quantizing and forwarding the received
signals for joint decoding at the CP, i.e. forward-and-decode (FaD) as in the
conventional CRAN, the RRHs can locally decode-and-forward (DaF) the user
messages to save the fronthaul capacity. In particular, we consider the uplink
transmission in an orthogonal frequency division multiple access (OFDMA)-based
UD-CRAN, where the proposed hybrid decoding is performed on each OFDMA
sub-channel (SC). We study a joint optimization of the processing mode
selections (DaF or FaD), user-SC assignments and the users' transmit power
allocations over all SCs to maximize their weighted-sum-rate subject to the
RRHs' individual fronthaul capacity constraints and the users' individual power
constraints. Although the problem is non-convex, we propose a Lagrange duality
based solution, which can be efficiently computed with good accuracy. Further,
we propose a low-complexity greedy algorithm which is shown to achieve close to
the optimal performance under practical setups. Simulation results show the
promising throughput gains of the proposed designs with hybrid decoding,
compared to the existing schemes that perform either DaF or FaD at all SCs.


title:
Extremal Numbers for 2 to 1 Directed Hypergraphs with Two Edges Part II:
  The Degenerate Cases

abstract:
  Let a 2 to 1 directed hypergraph be a 3-uniform hypergraph where every edge
has two tail vertices and one head vertex. For any such directed hypergraph F
let the nth extremal number of F be the maximum number of edges that any
directed hypergraph on n vertices can have without containing a copy of F.
There are actually two versions the directed hypergraph model for this problem:
the standard version where every triple of vertices is allowed to have up to
all three possible directed edges and the oriented version where each triple
can have at most one directed edge. In this paper, we determine the standard
extremal numbers and the oriented extremal numbers for four different directed
hypergraphs. Each has exactly two edges, and of the seven (nontrivial) 2 to 1
graphs with exactly two edges, these are the only four with extremal numbers
that are quadratic in n. The standard and oriented extremal numbers for the
other three directed hypergraphs with two edges are determined in a companion
paper.


title: An operadic approach to operator-valued free cumulants

abstract:
  An operadic framework is developed to explain the inversion formula relating
moments and cumulants in operator-valued free probability theory.


title:
Study on the magnetic measurement results of the injection system for
  CSNS/RCS

abstract:
  A combination of the H- stripping and phase space painting method is used to
accumulate a high intensity beam in the Rapid Cycling Synchrotron (RCS) of the
China Spallation Neutron Source (CSNS). The injection system for CSNS/RCS
consists of three kinds of magnets: four direct current magnets (BC1-BC4),
eight alternating current magnets (BH1-BH4 and BV1-BV4), two septum magnets
(ISEP1 and ISEP2). In this paper, the magnetic measurements of the injection
system were introduced and the data analysis was processed. The field
uniformity and magnetizing curves of these magnets were given, and then the
magnetizing fitting equations were obtained.


title: Heavy meson spectroscopy under strong magnetic field

abstract:
  Spectra of the neutral heavy mesons, $\eta_c(1S,2S)$, $J/\psi$, $\psi(2S)$,
$\eta_b(1S,2S,3S)$, $\Upsilon(1S,2S,3S)$, $D$, $D^\ast$, $B$, $B^\ast$, $B_s$
and $B_s^\ast$, in a homogeneous magnetic field are analyzed in a potential
model of constituent quarks. To obtain anisotropic wave functions and the
corresponding eigenvalues, the cylindrical Gaussian expansion method is
applied, where the wave functions for transverse and longitudinal directions in
the cylindrical coordinate are expanded by the Gaussian bases separately.
Energy level structures in the wide range of magnetic fields are obtained and
the deformation of the wave functions is shown, which reflects effects of the
spin mixing, the Zeeman splitting and quark Landau levels. The contribution
from the magnetic catalysis in heavy-light mesons is discussed as a change of
the light constituent quark mass.


title: Quadratic Leibniz conformal algebras

abstract:
  In this paper, we study a class of Leibniz conformal algebras called
quadratic Leibniz conformal algebras. An equivalent characterization of a
Leibniz conformal algebra $R=\mathbb{C}[\partial]V$ through three algebraic
operations on $V$ are given. By this characterization, several constructions of
quadratic Leibniz conformal algebras are presented. Moreover, one-dimensional
central extensions of quadratic Leibniz conformal algebras are considered using
some bilinear forms on $V$. In particular, we also study one-dimensional
Leibniz central extensions of quadratic Lie conformal algebras.


title:
The $\rho$-meson longitudinal leading-twist distribution amplitude
  within QCD background field theory

abstract:
  We revisit the $\rho$-meson longitudinal leading-twist distribution amplitude
(DA) $\phi_{2;\rho}^\|$ by using the QCD sum rules approach within the
background field theory. To improve the accuracy of the sum rules for its
moments $\langle\xi_{n;\rho}^\|\rangle$, we include the next-to-leading order
QCD correction to the perturbative part and keep all non-perturbative
condensates up to dimension-six consistently within the background field
theory. The first two moments read $\langle \xi_{2;\rho}^\| \rangle|_{1{\rm
GeV}} = 0.241(28)$ and $\langle \xi_{4;\rho}^\| \rangle|_{1{\rm GeV}} =
0.109(10)$, indicating a double humped behavior for $\phi_{2;\rho}^\|$ at small
energy scale. As an application, we apply them to the $B\to \rho $ transition
form factors within the QCD light-cone sum rules, which are key components for
the decay width $\Gamma(B\to \rho \ell \nu_\ell)$. To compare with the
world-average of $\Gamma(B\to \rho \ell \nu_\ell)$ issued by Particle Data
Group, we predict $|V_{\rm ub}| = 3.19^{+0.65}_{-0.62}$, which agrees with the
BABAR and Omn\`{e}s parameterization prediction within errors.


title:
Engineering the polar magneto-optical Kerr effect in strongly strained
  L10-MnAl films

abstract:
  We report the engineering of the polar magnetooptical (MO) Kerr effect in
perpendicularly magnetized L10-MnAl epitaxial films with remarkably tuned
magnetization, strain, and structural disorder by varying substrate temperature
(Ts) during molecular-beam epitaxy growth. The Kerr rotation was enhanced by a
factor of up to 5 with Ts increasing from 150 to 350 oC as a direct consequence
of the improvement of the magnetization. A similar remarkable tuning effect was
also observed on the Kerr ellipticity and the magnitude of the complex Kerr
angle, while the phase of the complex Kerr angle appears to be independent of
the magnetization. The combination of the good semiconductor compatibility, the
moderate coercivity of 0.3-8.2 kOe, the tunable polar MO Kerr effect of up to
~0.034o, and giant spin procession frequencies of up to ~180 GHz makes L10-MnAl
films a very interesting MO material. Our results give insights on both the
microscopic mechanisms of the MO Kerr effect in L10-MnAl alloys and their
scientific and technological application potential in the emerging spintronics
and ultrafast MO modulators.


title:
Composite Kernel Local Angular Discriminant Analysis for Multi-Sensor
  Geospatial Image Analysis

abstract:
  With the emergence of passive and active optical sensors available for
geospatial imaging, information fusion across sensors is becoming ever more
important. An important aspect of single (or multiple) sensor geospatial image
analysis is feature extraction - the process of finding "optimal" lower
dimensional subspaces that adequately characterize class-specific information
for subsequent analysis tasks, such as classification, change and anomaly
detection etc. In recent work, we proposed and developed an angle-based
discriminant analysis approach that projected data onto subspaces with maximal
"angular" separability in the input (raw) feature space and Reproducible Kernel
Hilbert Space (RKHS). We also developed an angular locality preserving variant
of this algorithm. In this letter, we advance this work and make it suitable
for information fusion - we propose and validate a composite kernel local
angular discriminant analysis projection, that can operate on an ensemble of
feature sources (e.g. from different sources), and project the data onto a
unified space through composite kernels where the data are maximally separated
in an angular sense. We validate this method with the multi-sensor University
of Houston hyperspectral and LiDAR dataset, and demonstrate that the proposed
method significantly outperforms other composite kernel approaches to sensor
(information) fusion.


title: An optimization approach to locally-biased graph algorithms

abstract:
  Locally-biased graph algorithms are algorithms that attempt to find local or
small-scale structure in a large data graph. In some cases, this can be
accomplished by adding some sort of locality constraint and calling a
traditional graph algorithm; but more interesting are locally-biased graph
algorithms that compute answers by running a procedure that does not even look
at most of the input graph. This corresponds more closely to what practitioners
from various data science domains do, but it does not correspond well with the
way that algorithmic and statistical theory is typically formulated. Recent
work from several research communities has focused on developing locally-biased
graph algorithms that come with strong complementary algorithmic and
statistical theory and that are useful in practice in downstream data science
applications. We provide a review and overview of this work, highlighting
commonalities between seemingly-different approaches, and highlighting
promising directions for future work.


title:
Tunable Electronic Properties of Multilayer Phosphorene and Its
  Nanoribbons

abstract:
  We study the effects of a vertical electric field on the electronic band
structure and transport in multilayer phosphorene and its nanoribbons. In
phosphorene, at a critical value of the vertical electric field ($E_c$), the
band gap closes and the band structure undergoes a massive-to-massless Dirac
fermion transition along the armchair direction. This transition is observable
in quantum Hall measurements, as the power-law dependence of the Landau-level
energy on the magnetic field $B$ goes from $\sim (n+1/2)B$ below $E_c$, to
$\sim [(n+1/2)B]^{2/3}$ at $E_c$, to $\sim [(n+1/2)B]^{1/2}$ above $E_c$. In
multilayer phosphorene nanoribbons (PNRs), the vertical electric field can be
employed to manipulate the midgap energy bands that are associated with edge
states, thereby giving rise to new device functionalities. We propose a
dual-edge-gate PNR structure that works as a quantum switch.


title:
Sparse Representation-Based Classification: Orthogonal Least Squares or
  Orthogonal Matching Pursuit?

abstract:
  Spare representation of signals has received significant attention in recent
years. Based on these developments, a sparse representation-based
classification (SRC) has been proposed for a variety of classification and
related tasks, including face recognition. Recently, a class dependent variant
of SRC was proposed to overcome the limitations of SRC for remote sensing image
classification. Traditionally, greedy pursuit based method such as orthogonal
matching pursuit (OMP) are used for sparse coefficient recovery due to their
simplicity as well as low time-complexity. However, orthogonal least square
(OLS) has not yet been widely used in classifiers that exploit the sparse
representation properties of data. Since OLS produces lower signal
reconstruction error than OMP under similar conditions, we hypothesize that
more accurate signal estimation will further improve the classification
performance of classifiers that exploiting the sparsity of data. In this paper,
we present a classification method based on OLS, which implements OLS in a
classwise manner to perform the classification. We also develop and present its
kernelized variant to handle nonlinearly separable data. Based on two
real-world benchmarking hyperspectral datasets, we demonstrate that class
dependent OLS based methods outperform several baseline methods including
traditional SRC and the support vector machine classifier.


title:
Magnetoconductivity in Weyl semimetals: Effect of chemical potential and
  temperature

abstract:
  We present the detailed analyses of magneto-conductivities in a Weyl
semimetal within Born and self-consistent Born approximations. In the presence
of the charged impurities, the linear magnetoresistance can happen when the
charge carriers are mainly from the zeroth (n=0) Landau level. Interestingly,
the linear magnetoresistance is very robust against the change of temperature,
as long as the charge carriers mainly come from the zeroth Landau level. We
denote this parameter regime as the high-field regime. On the other hand, the
linear magnetoresistance disappears once the charge carriers from the higher
Landau levels can provide notable contributions. Our analysis indicates that
the deviation from the linear magnetoresistance is mainly due to the deviation
of the longitudinal conductivity from the $1/B$ behavior. We found two
important features of the self-energy approximation: 1. a dramatic jump of
$\sigma_{xx}$, when the $n=1$ Landau level begins to contribute charge
carriers, which is the beginning point of the middle-field regime, when
decreasing the external magnetic field from high field; 2. In the low-field
regime $\sigma_{xx}$ shows a $B^{-5/3}$ behavior and results the
magnetoresistance $\rho_{xx}$ to show a $B^{1/3}$ behavior. The detailed and
careful numerical calculation indicates that the self-energy approximation
(including both the Born and the self-consistent Born approximations) does not
explain the recent experimental observation of linear magnetoresistance in Weyl
semimetals.


title:
Kernels of Wiener-Hopf plus Hankel operators with matching generating
  functions

abstract:
  Considered are Wiener--Hopf plus Hankel operators
$W(a)+H(b):L^p(\mathbb{R}^+)\to L^p(\mathbb{R}^+)$ with generating functions
$a$ and $b$ from a subalgebra of $L^\infty(\mathbb{R})$ containing almost
periodic functions and Fourier images of $L^1(\mathbb{R})$-functions. If the
generating functions $a$ and $b$ satisfy the matching condition
  \begin{equation*} a(t) a(-t)=b(t) b(-t),\quad t\in\mathbb{R},
  \end{equation*} an explicit description for the kernels and cokernels of the
operators mentioned is given.


title:
Efficiency of dispersive wave generation from a dual-frequency beat
  signal

abstract:
  The emission of dispersive waves (DWs) by temporal solitons can be described
as a cascaded four-wave mixing process triggered by a pair of monochromatic
continuous waves (CWs). We report experimental and numerical results
demonstrating that the efficiency of this process is strongly and non-trivially
affected by the frequency detuning of the CW pump lasers. We explain our
results by showing that individual cycles of the input dual-frequency beat
signal can evolve as higher-order solitons whose temporal compression and
soliton fission govern the DW efficiency. Analytical predictions based on the
detuning dependence of the soliton order are shown to be in excellent agreement
with experimental and numerical observations.


title:
Some remarks on Bridgeland stability conditions on K3 and Enriques
  surfaces

abstract:
  We give some remarks on our papers with Minamide and Yanagida on Bridgeland
stability conditions. We also give a remark on stability conditions on Enriques
surfaces, and give another proof of the projectivity of the coarse moduli
spaces of semi-stable objects, which were obtained by Nuer.


title:
Quantum Supremacy for Simulating A Translation-Invariant Ising Spin
  Model

abstract:
  We introduce an intermediate quantum computing model built from
translation-invariant Ising-interacting spins. Despite being non-universal, the
model cannot be classically efficiently simulated unless the polynomial
hierarchy collapses. Equipped with the intrinsic single-instance-hardness
property, a single fixed unitary evolution in our model is sufficient to
produce classically intractable results, compared to several other models that
rely on implementation of an ensemble of different unitaries (instances). We
propose a feasible experimental scheme to implement our Hamiltonian model using
cold atoms trapped in a square optical lattice. We formulate a procedure to
certify the correct functioning of this quantum machine. The certification
requires only a polynomial number of local measurements assuming measurement
imperfections are sufficiently small.


title: On the fixed points of the map $x \mapsto x^x$ modulo a prime, II

abstract:
  We study number theoretic properties of the map $x \mapsto x^{x} \mod{p}$,
where $x \in \{1,2,\ldots,p-1\}$, and improve on some recent upper bounds, due
to Kurlberg, Luca, and Shparlinski, on the number of primes $p < N$ for which
the map only has the trivial fixed point $x=1$.
  A key technical result, possibly of independent interest, is the existence of
subsets $\mathscr{N}_{q} \subset \{2,3,\ldots,q-1\}$ such that almost all
$k$-tuples of distinct integers $n_{1}, n_{2},\ldots,n_{k} \in \mathscr{N}_q$
are multiplicatively independent (if $k$ is not too large), and
$|\mathscr{N}_q| = q \cdot (1+o(1))$ as $q \to \infty$. For $q$ a large prime,
this is used to show that the number of solutions to a certain large and sparse
system of $\mathbb{F}_q$-linear forms $\{ \mathscr{L}_{n} \}_{n=2}^{q-1}$
"behaves randomly" in the sense that $|\{ \mathbf{v} \in \mathbb{F}_{q}^{d} :
\mathscr{L}_{n}(\mathbf{v}) =1, n = 2,3, \ldots, q-1 \}| \sim q^{d}(1-1/q)^{q}
\sim q^{d}/e$. (Here $d=\pi(q-1)$ and the coefficents of $\mathscr{L}_{n}$ are
given by the exponents in the prime power factorization of $n$.)


title:
Leibniz algebras associated with representations of Euclidean Lie
  algebra

abstract:
  In the present paper we describe Leibniz algebras with three-dimensional
Euclidean Lie algebra $\mathfrak{e}(2)$ as its liezation. Moreover, it is
assumed that the ideal generated by the squares of elements of an algebra
(denoted by $I$) as a right $\mathfrak{e}(2)$-module is associated to
representations of $\mathfrak{e}(2)$ in $\mathfrak{sl}_2({\mathbb{C}})\oplus
\mathfrak{sl}_2({\mathbb{C}}), \mathfrak{sl}_3({\mathbb{C}})$ and
$\mathfrak{sp}_4(\mathbb{C})$. Furthermore, we present the classification of
Leibniz algebras with general Euclidean Lie algebra ${\mathfrak{e(n)}}$ as its
liezation $I$ being an $(n+1)$-dimensional right ${\mathfrak{e(n)}}$-module
defined by transformations of matrix realization of $\mathfrak{e(n)}.$ Finally,
we extend the notion of a Fock module over Heisenberg Lie algebra to the case
of Diamond Lie algebra $\mathfrak{D}_k$ and describe the structure of Leibniz
algebras with corresponding Lie algebra $\mathfrak{D}_k$ and with the ideal $I$
considered as a Fock $\mathfrak{D}_k$-module.


title:
Wavelet decomposition of software entropy reveals symptoms of malicious
  code

abstract:
  Sophisticated malware authors can sneak hidden malicious code into portable
executable files, and this code can be hard to detect, especially if encrypted
or compressed. However, when an executable file switches between code regimes
(e.g. native, encrypted, compressed, text, and padding), there are
corresponding shifts in the file's representation as an entropy signal. In this
paper, we develop a method for automatically quantifying the extent to which
patterned variations in a file's entropy signal make it "suspicious." In
Experiment 1, we use wavelet transforms to define a Suspiciously Structured
Entropic Change Score (SSECS), a scalar feature that quantifies the
suspiciousness of a file based on its distribution of entropic energy across
multiple levels of spatial resolution. Based on this single feature, it was
possible to raise predictive accuracy on a malware detection task from 50.0% to
68.7%, even though the single feature was applied to a heterogeneous corpus of
malware discovered "in the wild." In Experiment 2, we describe how
wavelet-based decompositions of software entropy can be applied to a parasitic
malware detection task involving large numbers of samples and features. By
extracting only string and entropy features (with wavelet decompositions) from
software samples, we are able to obtain almost 99% detection of parasitic
malware with fewer than 1% false positives on good files. Moreover, the
addition of wavelet-based features uniformly improved detection performance
across plausible false positive rates, both in a strings-only model (e.g., from
80.90% to 82.97%) and a strings-plus-entropy model (e.g. from 92.10% to 94.74%,
and from 98.63% to 98.90%). Overall, wavelet decomposition of software entropy
can be useful for machine learning models for detecting malware based on
extracting millions of features from executable files.


title: Non-homotopicity of the linking set of algebraic plane curves

abstract:
  The linking set is an invariant of algebraic plane curves introduced by
Meilhan and the first author. It has been successfully used to detect several
examples of Zariski pairs, i.e. curves with the same combinatorics and
different embedding in $\mathds{CP}^2$. Differentiating Shimada's
$\pi_1$-equivalent Zariski pair by the linking set, we prove, in the present
paper, that this invariant is not determined by the fundamental group of the
curve.


title: An Extended Colored Zee-Babu Model

abstract:
  We study the extended colored Zee-Babu model introducing a vector-like quark
and singlet scalar. The active neutrino mass matrix and muon anomalous magnetic
moment are analyzed, which can be fitted to experimental data satisfying the
constraints from flavor changing neutral current. Then we discuss signature of
our model via vector-like quark production. In addition, the diphoton excess
can be explained with the contribution from vector-like quark


title: Pseudo antibunching on one single photon detector

abstract:
  In this paper, we proposed a pseudo antibunching effect on one single photon
detector. Though this pseudo antibunching effect is not a sign of the non
classical properties of the light field as the antibunching effect. It will
give some intresting properties to the photon statistics of the related fields,
such as the anticorrelation of photon number or intensity fluctuations of the
two input fields. This effect may have some potential application in future
especially in the quantum information field.


title:
Displacement exponent for loop-erased random walk on the Sierpi\'nski
  gasket

abstract:
  We prove that loop-erased random walks on finite pre-Sierpinski gaskets can
be extended to the infinite pre-Sierpinski gasket by virtue of the
`erasing-larger-loops-first' method, and obtain the asymptotic behavior of the
walk as the number of steps increases, in particular, the displacement exponent
and a law of the iterated logarithm.


title: The design and construction of the MICE Electron-Muon Ranger

abstract:
  The Electron-Muon Ranger (EMR) is a fully-active tracking-calorimeter
installed in the beam line of the Muon Ionization Cooling Experiment (MICE).
The experiment will demonstrate ionization cooling, an essential technology
needed for the realization of a Neutrino Factory and/or a Muon Collider. The
EMR is designed to measure the properties of low energy beams composed of
muons, electrons and pions, and perform the identification
particle-by-particle. The detector consists of 48 orthogonal layers of 59
triangular scintillator bars. The readout is implemented using FPGA custom made
electronics and commercially available modules. This article describes the
construction of the detector from its design up to its commissioning with
cosmic data.


title:
Search for the effect of massive bodies on atomic spectra and
  constraints on Yukawa-type interactions of scalar particles

abstract:
  We propose a new method to search for hypothetical scalar particles that have
feeble interactions with Standard-Model particles. In the presence of massive
bodies, these interactions produce a non-zero Yukawa-type scalar-field
magnitude. Using radio-frequency spectroscopy data of atomic dysprosium, as
well as atomic clock spectroscopy data, we constrain the Yukawa-type
interactions of a scalar field with the photon, electron, and nucleons for a
range of scalar-particle masses corresponding to length scales $ > 10$ cm. In
the limit as the scalar-particle mass $m_\phi \to 0$, our derived limits on the
Yukawa-type interaction parameters are: $\Lambda_\gamma \gtrsim 8 \times
10^{19}$ GeV, $\Lambda_e \gtrsim 1.3 \times 10^{19}$ GeV, and $\Lambda_N
\gtrsim 6 \times 10^{20}$ GeV. Our measurements also constrain combinations of
interaction parameters, which cannot otherwise be probed with traditional
anomalous-force measurements. We suggest further measurements to improve on the
current level of sensitivity.


title:
Adaptive control for trailing arm suspension with hydraulic cylinder
  spring under practical constraints

abstract:
  This paper presents an adaptive control strategy with LQ control of a
quarter-car, which is ameliorated to smoothly follow the dynamically changing
reference arm angle, in order to omit the heave sensor in this study.
Linearized plant parameters are initially derived from model equation and then
estimated by online estimator. LQ control method provides optimal control
effort with corresponding estimated plant parameters. The results of the
simulation are depicted in time domain. Weighted RMS values of the consequences
are suggested to assess the efficiency of the controller. Different road
conditions are considered in order to reveal the performance of the controller
in detail.


title: Quantum mechanics as an approximated model: A geometrodynamical approach

abstract:
  In this paper, we discuss a geometrodynamical approach to particle physics,
in which quantum mechanics is no more than an approximated model of nature in
the microscopic scale. We derive quantum mechanics from the concept of
non-local geometrodynamics. Using the concept of superoscillations, we obtain
the metric of the particles, which allows mapping this metric into the quantum
wavefunction representation.


title: Quantum computation using arrays of N polar molecules in pendular states

abstract:
  We investigate several aspects of realizing quantum computation using
entangled polar molecules in pendular states. Quantum algorithms typically
start from a product state |00...0> and we show that up to a negligible error,
the ground states of polar molecule arrays can be considered as the unentangled
qubit basis state |00...0>. This state can be prepared by simply allowing the
system to reach thermal equilibrium at low temperature (<1 mK). We also
evaluate entanglement, characterized by the concurrence of pendular state
qubits in dipole arrays as governed by the external electric field,
dipole-dipole coupling and number N of molecules in the array. In the parameter
regime that we consider for quantum computing, we find that qubit entanglement
is modest, typically no greater than 0.0001, confirming the negligible
entanglement in the ground state. We discuss methods for realizing quantum
computation in the gate model, measurement based model, instantaneous quantum
polynomial time circuits and the adiabatic model using polar molecules in
pendular states.


title:
A Quantum Optics Argument for the #P-hardness of a Class of
  Multidimensional Integrals

abstract:
  Matrix permanents arise naturally in the context of linear optical networks
fed with nonclassical states of light. In this letter we tie the computational
complexity of a class of multi-dimensional integrals to the permanents of large
matrices using a simple quantum optics argument. In this way we prove that
evaluating integrals in this class is \textbf{\#P}-hard. Our work provides a
new approach for using methods from quantum physics to prove statements in
computer science.


title:
Schwarz triangle functions and duality for certain parameters of the
  generalised Chazy equation

abstract:
  Schwarz triangle functions play a fundamental role in the solutions of the
generalised Chazy equation. Chazy has shown that for the parameters $k=2$ and
$3$, the equations can be linearised. We determine the Schwarz triangle
functions that represent the solutions in these cases. Some of these Schwarz
triangle functions also show up in the dual cases where $k=\frac{2}{3}$ and
$k=\frac{3}{2}$, which suggests intriguing connections between the solutions
for $k=2$ and $k=3$ with dihedral and tetrahedral symmetry respectively, and
$k=\frac{2}{3}, \frac{3}{2}$ with $G_2$ symmetry. Integrating the solutions
when $k=\frac{2}{3}$, we obtain flat $(2,3,5)$-distributions parametrised
algebraically by the corresponding Schwarz triangle functions. The Legendre
dual of these curves are also algebraic, can be computed quite easily and are
related to the integral curves of the dual generalised Chazy equation with
parameter $\frac{3}{2}$.


title: On de Sitter solutions in asymptotically safe $f(R)$ theories

abstract:
  The availability of scaling solutions in renormalisation group improved
versions of cosmology are investigated in the high-energy limit. We adopt
$f(R)$-type models of quantum gravity which display an interacting ultraviolet
fixed point at shortest distances. Expanding the gravitational fixed point
action to very high order in the curvature scalar, we detect a
convergence-limiting singularity in the complex field plane. Resummation
techniques including Pad\'e approximants as well as infinite order
approximations of the effective action are used to maximise the domain of
validity. We find that the theory displays near de Sitter solutions as well as
an anti-de Sitter solution in the UV whereas real de Sitter solutions, for
small curvature, appear to be absent. The significance of our results for
inflation, and implications for more general models of quantum gravity are
discussed.


title: Comic ray flux anisotropies caused by astrospheres

abstract:
  Huge astrospheres or stellar wind bubbles influence the propagation of cosmic
rays at energies up to the TeV range and can act as small-scale sinks
decreasing the cosmic ray flux. We model such a sink (in 2D) by a sphere of
radius 10\,pc embedded within a sphere of a radius of 1\,kpc. The cosmic ray
flux is calculated by means of backward stochastic differential equations from
an observer, which is located at $r_{0}$, to the outer boundary. It turns out
that such small-scale sinks can influence the cosmic ray flux at the observer's
location by a few permille (i.e\ a few 0.1\%), which is in the range of the
observations by IceCube, Milagro and other large area telescopes.


title: Gyrotrons for High-Power Terahertz Science and Technology at FIR UF

abstract:
  In this paper, we present the recent progress in the development of a series
of gyrotrons at FIR UF that have opened the road to many novel applications in
the high-power Terahertz science and technology. The current status of the
research in this actively developing field is illustrated by the most
representative examples in which the developed gyrotrons are used as powerful
and frequency tunable sources of coherent radiation operating in a CW regime.
Among them are high-precision spectroscopic techniques (most notably DNP-NMR,
ESR, XDMR, and studies of the hyperfine splitting of the energy levels of
positronium), treatment and characterization of advanced materials, new medical
technologies.


title: Distributed Coding of Multiview Sparse Sources with Joint Recovery

abstract:
  In support of applications involving multiview sources in distributed object
recognition using lightweight cameras, we propose a new method for the
distributed coding of sparse sources as visual descriptor histograms extracted
from multiview images. The problem is challenging due to the computational and
energy constraints at each camera as well as the limitations regarding
inter-camera communication. Our approach addresses these challenges by
exploiting the sparsity of the visual descriptor histograms as well as their
intra- and inter-camera correlations. Our method couples distributed source
coding of the sparse sources with a new joint recovery algorithm that
incorporates multiple side information signals, where prior knowledge (low
quality) of all the sparse sources is initially sent to exploit their
correlations. Experimental evaluation using the histograms of shift-invariant
feature transform (SIFT) descriptors extracted from multiview images shows that
our method leads to bit-rate saving of up to 43% compared to the
state-of-the-art distributed compressed sensing method with independent
encoding of the sources.


title:
Viscosity parameter in dissipative accretion flows with mass outflow
  around black holes

abstract:
  Numerical hydrodynamic simulation of inviscid and viscous flows have shown
that significant outflows could be produced from the CENtrifugal pressure
supported BOundary Layer or CENBOL of an advective disk. However, this barrier
is weakened in presence of viscosity, more so, if there are explicit energy
dissipations at the boundary layer itself. We study effects of viscosity and
energy dissipation theoretically on the outflow rate and show that as the
viscosity or energy dissipation (or both) rises, the prospect of formation of
outflows is greatly reduced, thereby verifying results obtained through
observations and numerical simulations. Indeed, we find that in a dissipative
viscous flow, shocks in presence of outflows can be produced only if the
Shakura-Sunyaev viscosity parameter {\alpha} is less than 0.2. This is a direct
consequence of modification of the Rankine-Hugoniot relation across the shock
in a viscous flow, when the energy dissipation and mass loss in the form of
outflows from the post-shock region are included. If we ignore the effects of
mass loss altogether, the standing dissipative shocks in viscous flows may
occur only if {\alpha} < 0.27. These limits are tighter than the absolute limit
of {\alpha} = 0.3 valid for a situation when the shock itself neither
dissipates energy nor any outflow is formed. We compute typical viscosity
parameters required to understand spectral and temporal properties of several
black hole candidates such as GX399-4, MAXI J1659-152 and MAXI J1836-194 and
find that required {\alpha} are indeed well within our prescribed limit.


title:
Effect of Heterogeneous Transmission Rate on Epidemic Spreading Over
  Scale Free Networks

abstract:
  In the present work the spread of epidemic is studied over complex networks
which are characterized by power law degree distribution of links and
heterogeneous rate of disease transmission. The random allocation of epidemic
transmission rates to the nodes results in the heterogeneity, which in turn
causes the segregation of nodes in terms of various sub populations. The aim of
the study is to gain microscopic insight into the effect of interactions among
various sub populations in the spreading processes of disease over such
networks. The discrete time Markov chain method based upon the susceptible
infected susceptible (SIS) model of diseases transmission has been used to
describe the spreading of epidemic over the networks. The study is
parameterized in terms of variable $\lambda$, defined as the number of contacts
a node makes with the fraction of its neighboring nodes. From the simulation
results, it is found that the spread of epidemic on such networks is critical
in terms of number of minimum contacts made by a node below which there is no
outbreak of disease. The degree of infection in these networks is assessed from
the size of epidemic defined in terms of fraction of infected nodes of the
total number and their corresponding level of infection. The results of the
parametric study demonstrates the dependence of the epidemic size upon number
of concurrent contacts made by a node ($\lambda$ ) and the average number of
links per node. In both these cases, the size of the epidemic is found to
increase with the corresponding increase in respective parameters.


title:
Numerical and analytical methods for bond pricing in short rate
  convergence models of interest rates

abstract:
  In this survey paper we discuss recent advances on short interest rate models
which can be formulated in terms of a stochastic differential equation for the
instantaneous interest rate (also called short rate) or a system of such
equations in case the short rate is assumed to depend also on other stochastic
factors. Our focus is on convergence models, which explain the evolution of
interest rate in connection with the adoption of Euro currency. Here, the
domestic short rate depends on a stochastic European short rate. In short rate
models, the bond prices, which determine the term structure of interest rate,
are obtained as solutions to partial differential equations. Analytical
solutions are available only in special cases; therefore we consider the
question of obtaining their approximations. We use both analytical and
numerical methods to get an approximate solution to the partial differential
equation for bond prices.


title:
Applicability of the continuum-discretized coupled-channels method to
  the deuteron breakup at low energies

abstract:
  We re-examine the deuteron elastic breakup cross sections on 12C and 10Be at
low incident energies, for which a serious discrepancy between the
continuum-discretized coupled-channels method (CDCC) and the
Faddeev-Alt-Grassberger-Sandhas theory (FAGS) was pointed out. We show the
closed-channels neglected in the preceding study affect significantly the
breakup cross section calculated with CDCC, resulting in good agreement with
the result of FAGS.


title: All-optical sampling and magnification based on XPM-induced focusing

abstract:
  We theoretically and experimentally investigate the design of an all-optical
noiseless magnification and sampling function free from any active gain medium
and associated high-power continuous wave pump source. The proposed technique
is based on the co-propagation of an arbitrary shaped signal together with an
orthogonally polarized intense fast sinusoidal beating within a normally
dispersive optical fiber. Basically, the strong nonlinear phase shift induced
by the sinusoidal pump beam on the orthogonal weak signal through cross-phase
modulation turns the defocusing regime into localized temporal focusing
effects. This periodic focusing is then responsible for the generation of a
high-repetition-rate temporal comb upon the incident signal whose amplitude is
directly proportional to its initial shape. This internal redistribution of
energy leads to a simultaneous sampling and magnification of the signal
intensity profile. This process allows us to experimentally demonstrate a
40-GHz sampling operation as well as an 8-dB magnification of an arbitrary
shaped nanosecond signal around 1550 nm in a 5-km long normally dispersive
fiber. The experimental observations are in quantitative agreement with
numerical and theoretical analysis.


title:
A platform-independent robot control architecture for multiple
  therapeutic scenarios

abstract:
  While social robots are developed to provide assistance to users through
social interactions, their behaviors are dominantly pre-programmed and
remote-controlled. Despite the numerous robot control architectures being
developed, very few offer reutilization opportunities in various therapeutic
contexts. To bridge this gap, we propose a robot control architecture to be
applied in different scenarios taking into account requirements from both
therapeutic and robotic perspectives. As robot behaviors are kept at an
abstract level and afterward mapped with the robot's morphology, the proposed
architecture accommodates its applicability to a variety of social robot
platforms.


title: Top quark mass measurements with the CMS experiment at the LHC

abstract:
  Measurements of the top quark mass are presented, obtained from CMS data
collected in proton proton collisions at the LHC at centre-of-mass energies of
7 TeV and 8 TeV. The mass of the top quark is measured using several methods
and channels, including the reconstructed invariant mass distribution of the
top quark as well as measurements based on charged particle information. The
dependence of the mass measurement on the kinematic phase space is
investigated. The results of the various channels are combined and compared to
the world average. The top mass is extracted from the inclusive top quark pair
production cross section measured at CMS.


title: Photonic crystals to enhance light extraction from 2D materials

abstract:
  We propose a scheme for coupling 2D materials to an engineered cavity based
on a defective rod type photonic crystal lattice. We show results from
numerical modelling of the suggested cavity design, and propose using the
height profile of a 2D material transferred on top of the cavity to maximise
coupling between exciton recombination and the cavity mode. The photonic
structure plays a key role in enhancing the launch efficiency, by improving the
directionality of the emitted light to better couple it into an external
optical system. When using the photonic structure, we measured an increase in
the extraction ratio by a factor of 3.4. We investigated the variations in the
flux spectrum when the radius of the rods is modified, and when the 2D material
droops to a range of different heights within the cavity. We found an optimum
enhancement when the rods have a radius equal to 0.165 times the lattice
constant, this enhancement reduces when the radius is reduced or increased.
Finally, we discuss the possible use of solid immersion lenses, in combination
with our photonic structure, to further enhance the launch efficiency and to
improve vertical confinement of the cavity mode.


title:
Exchange effect and magneto-plasmon mode dispersion in an anisotropic
  two-dimensional electronic system

abstract:
  The exchange effect and the magneto-plasmon mode dispersion are studied
theoretically for an anisotropic two-dimensional electronic system in the
presence of an uniform perpendicular magnetic field. Employing an effective
low-energy model with anisotropic effective masses, which is relevant for a
monolayer of phosphorus, the exchange effect due to the electron-electron
interaction is treated within the self-consistent Hartree-Fock approximation.
The magneto-plasmon mode dispersion is obtained by solving a Bethe-Salpeter
equation for the electron density-density correlation function within the
ladder diagram approximation. It is found that the exchange effect is reduced
in the anisotropic system in comparison with the isotropic one. The
magneto-plasmon mode dispersion shows a clear dependence on the direction of
the wave vector.


title: On syntomic regulators I: constructions

abstract:
  We show that classical Chern classes from higher ($p$-adic) $K$-theory to
syntomic cohomology extend to logarithmic syntomic cohomology. These Chern
classes are compatible -- in a suitable sense -- with addition, products, and
$\lambda$-operations. They are also compatible with the canonical Gysin
sequences and, via period maps, with logarithmic \'etale Chern classes.
Moreover, they induce logarithmic crystalline Chern classes. This uses as a
critical new ingredient the recent comparison of syntomic cohomology with
$p$-adic nearby cycles and $p$-adic motivic cohomology.


title: The Fukaya category pairs with Lagrangian cobordisms

abstract:
  Fix a suitably convex, exact symplectic manifold M. We consider the stable
oo-category Lag(M) of non-compact Lagrangians whose (higher) morphisms are
(higher) Lagrangian cobordisms between them. We show that this oo-category
pairs with the Fukaya category Fuk(M) of compact branes. In fact, we also show
that there is a subcategory of Lag(M) which pairs with the wrapped Fukaya
category of M. This is a first step in a project to enrich wrapped Fukaya
categories over cobordism spectra. As a corollary, we show that cobordant
compact branes are equivalent in the Fukaya category. We will also mention
several other applications (without proof) of the oo-categorical appraoch: One
can realize Seidel's representation as a \pi_0-level consequence of a map of
spaces; stable cobordism groups of non-compact branes map to Floer cohomology
groups; some of Biran-Cornea's results can be recovered from the colored planar
operad associated to the s-dot constructions of each category; and there is an
Eoo map of spectra from exact Lagrangian cobordisms in Euclidean space to the
integers.


title:
Energy backflow in strongly coupled non-Markovian continuous-variables
  systems

abstract:
  By employing the full counting statistics formalism, we characterize the
first moment of energy that is exchanged during a generally non-Markovian
evolution in non-driven continuous variables systems. In particular, we focus
on the evaluation of the energy flowing back from the environment into the open
quantum system. We apply these results to the quantum Brownian motion, where
these quantities are calculated both analytically, under the weak coupling
assumption, and numerically also in the strong coupling regime. Finally, we
characterize the non-Markovianity of the reduced dynamics through a recently
introduced witness based on the so-called Gaussian interferometric power and we
discuss its relationship with the energy backflow measure.


title:
Form factors of the monodromy matrix entries in gl(2|1)-invariant
  integrable models

abstract:
  We study integrable models solvable by the nested algebraic Bethe ansatz and
described by $\mathfrak{gl}(2|1)$ or $\mathfrak{gl}(1|2)$ superalgebras. We
obtain explicit determinant representations for form factors of the monodromy
matrix entries. We show that all form factors are related to each other at
special limits of the Bethe parameters. Our results allow one to obtain
determinant formulas for form factors of local operators in the supersymmetric
t-J model.


title:
Biaxial strain tuned thermoelectric properties in monolayer
  $\mathrm{PtSe_2}$

abstract:
  Strain engineering is a very effective method to tune electronic, optical,
topological and thermoelectric properties of materials. In this work, we
systematically study biaxial strain dependence of electronic structures and
thermoelectric properties (both electron and phonon parts) of monolayer
$\mathrm{PtSe_2}$ with generalized gradient approximation (GGA) plus spin-orbit
coupling (SOC) for electron part and GGA for phonon part. Calculated results
show that compressive or tensile strain can induce conduction band minimum
(CBM) or valence band maximum (VBM) transition, which produces important
effects on Seebeck coefficient. It is found that compressive or tensile strain
can induce significantly enhanced n- or p-type Seebeck coefficient at the
critical strain of CBM or VBM transition, which can be explained by
strain-induced band convergence. Another essential strain effect is that
tensile strain can produce significantly reduced lattice thermal conductivity,
and the room temperature lattice thermal conductivity at the strain of -4.02\%
can decrease by about 60\% compared to unstrained one, which is very favorable
for high $ZT$. To estimate efficiency of thermoelectric conversion, the figure
of merit $ZT$ can be obtained by empirical scattering time $\tau$. Calculated
$ZT$ values show that strain indeed is a very effective strategy to achieve
enhanced thermoelectric properties, especially for p-type doping. Tuning
thermoelectric properties with strain also can be applied to other
semiconducting transition-metal dichalcogenide monolayers $\mathrm{MX_2}$
(M=Zr, Hf, Mo, W and Pt; X=S, Se and Te).


title: Cryogenic setup for trapped ion quantum computing

abstract:
  We report on the design of a cryogenic setup for trapped ion quantum
computing containing a segmented surface electrode trap. The heat shield of our
cryostat is designed to attenuate alternating magnetic field noise, resulting
in 120~dB reduction of 50~Hz noise along the magnetic field axis. We combine
this efficient magnetic shielding with high optical access required for single
ion addressing as well as for efficient state detection by placing two lenses
each with numerical aperture 0.23 inside the inner heat shield. The cryostat
design incorporates vibration isolation to avoid decoherence of optical qubits
due to the motion of the cryostat. We measure vibrations of the cryostat of
less than $\pm$20~nm over 2~s. In addition to the cryogenic apparatus, we
describe the setup required for an operation with
$^{\mathrm{40}}$Ca$^{\mathrm{+}}$ and $^{\mathrm{88}}$Sr$^{\mathrm{+}}$ ions.
The instability of the laser manipulating the optical qubits in
$^{\mathrm{40}}$Ca$^{\mathrm{+}}$ is characterized yielding a minimum of its
Allan deviation of 2.4$\cdot$10$^{\mathrm{-15}}$ at 0.33~s. To evaluate the
performance of the apparatus, we trapped $^{\mathrm{40}}$Ca$^{\mathrm{+}}$
ions, obtaining a heating rate of 2.14(16)~phonons/s and a Gaussian decay of
the Ramsey contrast with a 1/e-time of 18.2(8)~ms.


title: Intercalates and Discrepancy in Random Latin Squares

abstract:
  An intercalate in a Latin square is a $2\times2$ Latin subsquare. Let $N$ be
the number of intercalates in a uniformly random $n\times n$ Latin square. We
prove that asymptotically almost surely
$N\ge\left(1-o\left(1\right)\right)\,n^{2}/4$, and that
$\mathbb{E}N\le\left(1+o\left(1\right)\right)\,n^{2}/2$ (therefore
asymptotically almost surely $N\le fn^{2}$ for any $f\to\infty$). This
significantly improves the previous best lower and upper bounds. We also give
an upper tail bound for the number of intercalates in two fixed rows of a
random Latin square. In addition, we discuss a problem of Linial and Luria on
low-discrepancy Latin squares.


title: Dependency Language Models for Transition-based Dependency Parsing

abstract:
  In this paper, we present an approach to improve the accuracy of a strong
transition-based dependency parser by exploiting dependency language models
that are extracted from a large parsed corpus. We integrated a small number of
features based on the dependency language models into the parser. To
demonstrate the effectiveness of the proposed approach, we evaluate our parser
on standard English and Chinese data where the base parser could achieve
competitive accuracy scores. Our enhanced parser achieved state-of-the-art
accuracy on Chinese data and competitive results on English data. We gained a
large absolute improvement of one point (UAS) on Chinese and 0.5 points for
English.


title:
Magnetic Skyrmion Transport in a Nanotrack With Spatially Varying
  Damping and Non-adiabatic Torque

abstract:
  Reliable transport of magnetic skyrmions is required for any future
skyrmion-based information processing devices. Here we present a micromagnetic
study of the in-plane current-driven motion of a skyrmion in a ferromagnetic
nanotrack with spatially sinusoidally varying Gilbert damping and/or
non-adiabatic spin-transfer torque coefficients. It is found that the skyrmion
moves in a sinusoidal pattern as a result of the spatially varying Gilbert
damping and/or non-adiabatic spin-transfer torque in the nanotrack, which could
prevent the destruction of the skyrmion caused by the skyrmion Hall effect. The
results provide a guide for designing and developing the skyrmion transport
channel in skyrmion-based spintronic applications.


title: Distributed Graph Clustering by Load Balancing

abstract:
  Graph clustering is a fundamental computational problem with a number of
applications in algorithm design, machine learning, data mining, and analysis
of social networks. Over the past decades, researchers have proposed a number
of algorithmic design methods for graph clustering. However, most of these
methods are based on complicated spectral techniques or convex optimisation,
and cannot be applied directly for clustering many networks that occur in
practice, whose information is often collected on different sites. Designing a
simple and distributed clustering algorithm is of great interest, and has wide
applications for processing big datasets. In this paper we present a simple and
distributed algorithm for graph clustering: for a wide class of graphs that are
characterised by a strong cluster-structure, our algorithm finishes in a
poly-logarithmic number of rounds, and recovers a partition of the graph close
to an optimal partition. The main component of our algorithm is an application
of the random matching model of load balancing, which is a fundamental protocol
in distributed computing and has been extensively studied in the past 20 years.
Hence, our result highlights an intrinsic and interesting connection between
graph clustering and load balancing. At a technical level, we present a purely
algebraic result characterising the early behaviours of load balancing
processes for graphs exhibiting a cluster-structure. We believe that this
result can be further applied to analyse other gossip processes, such as rumour
spreading and averaging processes.


title:
ExB flow-induced shearing-merging of filaments: a Ginzburg-Landau model
  of Edge-Localized Mode cycles

abstract:
  We derive and study a simple 1D nonlinear model for Edge Localized Mode (ELM)
cycles. The nonlinear dynamics of a resistive ballooning mode is modeled via a
single nonlinear equation of the Ginzburg-Landau type with a radial frequency
gradient due to a prescribed ExB shear layer of finite extent. The nonlinearity
is due to the feedback of the mode on the profile. We identify a novel
mechanism, whereby the ELM only crosses the linear stability boundary once, and
subsequently stays in the nonlinear regime for the full duration of the cycles.
This is made possible by the shearing and merging of filaments by the ExB flow,
which forces the system to oscillate between a radially-uniform solution and a
non-uniform solitary - wave like solution. The model predicts a 'phase-jump'
correlated with the ELM bursts.


title: On the representations of 2-groups in {Baez-Crans} 2-vector spaces

abstract:
  We prove that the theory of representations of a finite 2-group $\mathbb{G}$
in Baez-Crans 2-vector spaces over a field $k$ of characteristic zero
essentially reduces to the theory of $k$-linear representations of the group of
isomorphism classes of objects of $\mathbb{G}$, the remaining homotopy
invariants of $\mathbb{G}$ playing no role. It is also argued that a similar
result is expected to hold for topological representations of compact
topological 2-groups in suitable topological Baez-Crans 2-vector spaces.


title: Local Helioseismology of Emerging Active Regions: A Case Study

abstract:
  Local helioseismology provides a unique opportunity to investigate the
subsurface structure and dynamics of active regions and their effect on the
large-scale flows and global circulation of the Sun. We use measurements of
plasma flows in the upper convection zone, provided by the Time-Distance
Helioseismology Pipeline developed for analysis of solar oscillation data
obtained by Helioseismic and Magnetic Imager (HMI) on Solar Dynamics
Observatory (SDO), to investigate the subsurface dynamics of emerging active
region NOAA 11726. The active region emergence was detected in deep layers of
the convection zone about 12 hours before the first bipolar magnetic structure
appeared on the surface, and 2 days before the emergence of most of the
magnetic flux. The speed of emergence determined by tracking the flow
divergence with depth is about 1.4 km/s, very close to the emergence speed in
the deep layers. As the emerging magnetic flux becomes concentrated in sunspots
local converging flows are observed beneath the forming sunspots. These flows
are most prominent in the depth range 1-3 Mm, and remain converging after the
formation process is completed. On the larger scale converging flows around
active region appear as a diversion of the zonal shearing flows towards the
active region, accompanied by formation of a large-scale vortex structure. This
process occurs when a substantial amount of the magnetic flux emerged on the
surface, and the converging flow pattern remains stable during the following
evolution of the active region. The Carrington synoptic flow maps show that the
large-scale subsurface inflows are typical for active regions. In the deeper
layers (10-13 Mm) the flows become diverging, and surprisingly strong beneath
some active regions. In addition, the synoptic maps reveal a complex evolving
pattern of large-scale flows on the scale much larger than supergranulation.


title: Hankel and Toeplitz operators: continuous and discrete representations

abstract:
  We find a relation guaranteeing that Hankel operators realized in the space
of sequences $\ell^2 ({\Bbb Z}_{+}) $ and in the space of functions $L^2 ({\Bbb
R}_{+}) $ are unitarily equivalent. This allows us to obtain exhaustive
spectral results for two classes of unbounded Hankel operators in the space
$\ell^2 ({\Bbb Z}_{+}) $ generalizing in different directions the classical
Hilbert matrix. We also discuss a link between representations of Toeplitz
operators in the spaces $\ell^2 ({\Bbb Z}_{+}) $ and $L^2 ({\Bbb R}_{+}) $.


title: Stochastic $k$-Center and $j$-Flat-Center Problems

abstract:
  Solving geometric optimization problems over uncertain data have become
increasingly important in many applications and have attracted a lot of
attentions in recent years. In this paper, we study two important geometric
optimization problems, the $k$-center problem and the $j$-flat-center problem,
over stochastic/uncertain data points in Euclidean spaces. For the stochastic
$k$-center problem, we would like to find $k$ points in a fixed dimensional
Euclidean space, such that the expected value of the $k$-center objective is
minimized. For the stochastic $j$-flat-center problem, we seek a $j$-flat
(i.e., a $j$-dimensional affine subspace) such that the expected value of the
maximum distance from any point to the $j$-flat is minimized. We consider both
problems under two popular stochastic geometric models, the existential
uncertainty model, where the existence of each point may be uncertain, and the
locational uncertainty model, where the location of each point may be
uncertain. We provide the first PTAS (Polynomial Time Approximation Scheme) for
both problems under the two models. Our results generalize the previous results
for stochastic minimum enclosing ball and stochastic enclosing cylinder.


title: Non-elementary classes of representable posets

abstract:
  A poset is $(\omega,C)$-representable if it can be embedded into a field of
sets in such a way that all existing joins, and all existing \emph{finite}
meets are preserved. We show that the class of $(\omega,C)$-representable
posets cannot be axiomatized in first order logic using the standard language
of posets. We generalize this result to $(\alpha,\beta)$-representable posets
for certain values of $\alpha$ and $\beta$.


title: Special Values of L-functions for Orthogonal Groups

abstract:
  This is an announcement of certain rationality results for the critical
values of the degree-2n L-functions attached to GL(1) $\times$ SO(n, n) over
$\mathbb Q$ for an even positive integer n. The proof follows from studying the
rank-one Eisenstein cohomology for SO(n + 1, n + 1).


title:
Universal dynamics of density correlations at the transition to
  many-body localized state

abstract:
  Within one-dimensional disordered models of interacting fermions we perform a
numerical study of several dynamical density correlations, which can serve as
hallmarks of the transition to the many-body localized state. Results confirm
that density-wave correlations exhibit quite abrupt change with the increasing
disorder, with nonvanishing long-time value characteristic for nonergodic
phase. In addition, our results reveal in a wide time-window a logarithmic
variation of correlations in time, which we can bring in connection with the
anomalous behavior of the dynamical conductivity near the transition. Our
result support the view that transition to many-body localization can be
characterized by universal dynamical exponents.