title:
A single-state semi-quantum key distribution protocol and its security
  proof

abstract:
  Semi-quantum key distribution (SQKD) can share secret keys by using less
quantum resource than its fully quantum counterparts, and this likely makes
SQKD become more practical and realizable. In this paper, we present a new SQKD
protocol by introducing the idea of B92 into semi-quantum key distribution and
prove its unconditional security. In this protocol, the sender Alice just sends
one qubit to the classical Bob and Bob just prepares one state in the
preparation process. Indeed the classical user's measurement is not necessary
either. This protocol can reduce some quantum communication and make it easier
to be implemented. It can be seen as the semi-quantum version of B92 protocol,
comparing to the protocol BKM2007 as the semi-quantum version of BB84 in fully
quantum cryptography. We verify it has higher key rate and therefore is more
efficient. Specifically we prove it is unconditionally secure by computing a
lower bound of the key rate in the asymptotic scenario from information theory
aspect. Then we can find a threshold value of errors such that for all error
rates less than this value, the secure key can be established between the
legitimate users definitely. We make an illustration of how to compute the
threshold value in case of the reverse channel is a depolarizing one with
parameter $p$. Though the threshold value is a little smaller than those of
some existed SQKD protocols, it can be comparable to the B92 protocol in fully
quantum cryptography.


title:
Analyses and improvement of a broadcasting multiple blind signature
  scheme based on quantum GHZ entanglement

abstract:
  A broadcasting multiple blind signature scheme based on quantum GHZ
entanglement has been presented recently by Tian et al. It is said that the
scheme's unconditional security is guaranteed by adopting quantum key
preparation, quantum encryption algorithm and quantum entanglement. In this
paper, we prove that each signatory can get the signed message just by an
intercept-resend attack. Then, we show there still exists some participant
attacks and external attacks. Specifically, we verify the message sender Alice
can impersonate each signatory to sign the message at will, and so is the
signature collector Charlie. Also, we demonstrate that the receiver Bob can
forge the signature successfully, and with respect to the external attacks, the
eavesdropper Eve can modify the signature at random. Besides, we discover Eve
can change the signed message at will, and Eve can impersonate Alice as the
message sender without being discovered. In particular, we propose an improved
scheme based on the original one and show that it is secure against not only
the attacks mentioned above but also some collusion attacks.


title:
Transition from Fireball to Poynting-flux-dominated Outflow in
  Three-Episode GRB 160625B

abstract:
  The ejecta composition is an open question in gamma-ray bursts (GRB) physics.
Some GRBs possess a quasi-thermal spectral component in the time-resolved
spectral analysis, suggesting a hot fireball origin. Others show a featureless
non-thermal spectrum known as the "Band" function, consistent with a
synchrotron radiation origin and suggesting that the jet is
Poynting-flux-dominated at the central engine and likely in the emission region
as well. There are also bursts showing a sub-dominant thermal component and a
dominant synchrotron component suggesting a likely hybrid jet composition. Here
we report an extraordinarily bright GRB 160625B, simultaneously observed in
gamma-rays and optical wavelengths, whose prompt emission consists of three
isolated episodes separated by long quiescent intervals, with the durations of
each "sub-burst" being $\sim$ 0.8 s, 35 s, and 212 s, respectively. Its high
brightness (with isotropic peak luminosity L$_{\rm p, iso}\sim 4\times 10^{53}$
erg/s) allows us to conduct detailed time-resolved spectral analysis in each
episode, from precursor to main burst and to extended emission. The spectral
properties of the first two sub-bursts are distinctly different, allowing us to
observe the transition from thermal to non-thermal radiation between
well-separated emission episodes within a single GRB. Such a transition is a
clear indication of the change of jet composition from a fireball to a
Poynting-flux-dominated jet.


title: Spectral Classification of Coupling Regimes in the Quantum Rabi Model

abstract:
  The quantum Rabi model is in the scientific spotlight due to the recent
theoretical and experimental progress. Nevertheless, a full-fledged
classification of its coupling regimes remains as a relevant open question. We
propose a spectral classification dividing the coupling regimes into three
regions based on the validity of perturbative criteria on the quantum Rabi
model, which allows us the use of exactly solvable effective Hamiltonians.
These coupling regimes are i) the perturbative ultrastrong coupling regime
which comprises the Jaynes-Cummings model, ii) a region where non-perturbative
ultrastrong and non-perturbative deep strong coupling regimes coexist, and iii)
the perturbative deep strong coupling regime. We show that this spectral
classification depends not only on the ratio between the coupling strength and
the natural frequencies of the unperturbed parts, but also on the energy to
which the system can access. These regimes additionally discriminate the
completely different behaviors of several static physical properties, namely
the total number of excitations, the photon statistics of the field, and the
cavity-qubit entanglement. Finally, we explain the dynamical properties which
are traditionally associated to the deep strong coupling regime, such as the
collapses and revivals of the state population, in the frame of the proposed
spectral classification.


title:
Characterization of the inner disk around HD 141569 A from Keck/NIRC2
  L-band vortex coronagraphy

abstract:
  HD 141569 A is a pre-main sequence B9.5 Ve star surrounded by a prominent and
complex circumstellar disk, likely still in a transition stage from
protoplanetary to debris disk phase. Here, we present a new image of the third
inner disk component of HD 141569 A made in the L' band (3.8 micron) during the
commissioning of the vector vortex coronagraph recently installed in the
near-infrared imager and spectrograph NIRC2 behind the W.M. Keck Observatory
Keck II adaptive optics system. We used reference point spread function
subtraction, which reveals the innermost disk component from the inner working
distance of $\simeq 23$ AU and up to $\simeq 70$ AU. The spatial scale of our
detection roughly corresponds to the optical and near-infrared scattered light,
thermal Q, N and 8.6 micron PAH emission reported earlier. We also see an
outward progression in dust location from the L'-band to the H-band (VLT/SPHERE
image) to the visible (HST/STIS image), likely indicative of dust blowout. The
warm disk component is nested deep inside the two outer belts imaged by HST
NICMOS in 1999 (respectively at 406 and 245 AU). We fit our new L'-band image
and spectral energy distribution of HD 141569 A with the radiative transfer
code MCFOST. Our best-fit models favor pure olivine grains, and are consistent
with the composition of the outer belts. While our image shows a putative
very-faint point-like clump or source embedded in the inner disk, we did not
detect any true companion within the gap between the inner disk and the first
outer ring, at a sensitivity of a few Jupiter masses.


title:
Insights from Asteroseismology of Massive Stars: The Need for Additional
  Angular Momentum Transport Mechanisms

abstract:
  In massive stars, rotation and oscillatory waves can have a tight interplay.
In order to assess the importance of additional angular momentum transport
mechanisms other than rotation, we compare the asteroseismic properties of a
uniformly rotating model and a differentially rotating one. Accordingly, we
employ the observed period spacing of 36 dipole g-modes in the Kepler $\sim3.2$
M$_\odot$ target KIC 7760680 to discriminate between these two models. We favor
the uniformly rotating model, which fully satisfies all observational
constraints. Therefore, efficient angular momentum transport by additional
mechanisms such as internal gravity waves, heat-driven modes and magnetic field
is needed during early main sequence evolution of massive stars.


title:
The W. M. Keck Observatory infrared vortex coronagraph and a first image
  of HIP79124 B

abstract:
  An optical vortex coronagraph has been implemented within the NIRC2 camera on
the Keck II telescope and used to carry out on-sky tests and observations. The
development of this new L'-band observational mode is described, and an initial
demonstration of the new capability is presented: a resolved image of the
low-mass companion to HIP79124, which had previously been detected by means of
interferometry. With HIP79124 B at a projected separation of 186.5 mas, both
the small inner working angle of the vortex coronagraph and the related imaging
improvements were crucial in imaging this close companion directly. Due to
higher Strehl ratios and more relaxed contrasts in L' band versus H band, this
new coronagraphic capability will enable high-contrast small-angle observations
of nearby young exoplanets and disks on a par with those of shorter-wavelength
extreme adaptive optics coronagraphs.


title: Following Gaze Across Views

abstract:
  Following the gaze of people inside videos is an important signal for
understanding people and their actions. In this paper, we present an approach
for following gaze across views by predicting where a particular person is
looking throughout a scene. We collect VideoGaze, a new dataset which we use as
a benchmark to both train and evaluate models. Given one view with a person in
it and a second view of the scene, our model estimates a density for gaze
location in the second view. A key aspect of our approach is an end-to-end
model that solves the following sub-problems: saliency, gaze pose, and
geometric relationships between views. Although our model is supervised only
with gaze, we show that the model learns to solve these subproblems
automatically without supervision. Experiments suggest that our approach
follows gaze better than standard baselines and produces plausible results for
everyday situations.


title: Non-isotrivial elliptic surfaces with non-zero average root number

abstract:
  We consider the problem of finding $1$-parameter families of elliptic curves
whose root number does not average to zero as the parameter varies in
$\mathbb{Z}$. We classify all such families when the degree of the coefficients
(in the parameter $t$) is less than or equal to $2$ and we compute the rank
over $\mathbb{Q}(t)$ of all these families. Also, we compute explicitly the
average of the root numbers for some of these families highlighting some
special cases. Finally, we prove some results on the possible values average
root numbers can take, showing for example that all rational number in $[-1,1]$
are average root numbers for some $1$-parameter family.


title: Resilience of the quantum Rabi model in circuit QED

abstract:
  In circuit quantum electrodynamics (circuit QED), an artificial "circuit
atom" can couple to a quantized microwave radiation much stronger than its real
atomic counterpart. The celebrated quantum Rabi model describes the simplest
interaction of a two-level system with a single-mode boson field. When the
coupling is large enough, the bare multilevel structure of a realistic circuit
atom cannot be ignored even if the circuit is strongly anharmonic. We explored
this situation theoretically for flux (fluxonium) and charge (Cooper pair box)
type multi-level circuits tuned to their respective flux/charge degeneracy
points. We identified which spectral features of the quantum Rabi model survive
and which are renormalized for large coupling. Despite significant
renormalization of the low-energy spectrum in the fluxonium case, the key
quantum Rabi feature -- nearly-degenerate vacuum consisting of an atomic state
entangled with a multi-photon field -- appears in both types of circuits when
the coupling is sufficiently large. Like in the quantum Rabi model, for very
large couplings the entanglement spectrum is dominated by only two, nearly
equal eigenvalues, in spite of the fact that a large number of bare atomic
states are actually involved in the atom-resonator ground state. We interpret
the emergence of the two-fold degeneracy of the vacuum of both circuits as an
environmental suppression of flux/charge tunneling due to their dressing by
virtual low-/high-impedance photons in the resonator. For flux tunneling, the
dressing is nothing else than the shunting of a Josephson atom with a large
capacitance of the resonator. Suppression of charge tunneling is a
manifestation of the dynamical Coulomb blockade of transport in tunnel
junctions connected to resistive leads.


title: Hard Capacitated Set Cover and Uncapacitated Geometric Set Cover

abstract:
  The first part of this report describes the following result that,
logarithmic approximation factor for hard capacitated set cover can be achieved
from Wolsey's work [9], using a simpler and more intuitive analysis. We further
show in our work, that O(log n) approximation factor can be achieved for the
same problem by applying analysis of general set cover to analyze Wolsey's
algorithm [5]. This work is based on the key observation that we make in Lemma
3 of this report. The second part of the report describes the geometric hitting
set problem, where X is a ground set of points in a plane and S is a set of
axis parallel rectangles. It is shown that epsilon-nets of size O(1/epsilon log
log 1/epsilon) can be computed in polynomial time. Applying Bronnimann and
Goodrich result [3] gives the hitting set of size O(log log OPT) for this
problem.


title:
Quantum and thermal melting of stripe forming systems with competing
  long ranged interactions

abstract:
  We study the quantum melting of stripe phases in models with competing short
range and long range interactions decaying with distance as $1/r^{\sigma}$ in
two space dimensions. At zero temperature we find a two step disordering of the
stripe phases with the growth of quantum fluctuations. A quantum critical point
separating a phase with long range positional order from a phase with long
range orientational order is found when $\sigma \leq 4/3$, which includes the
Coulomb interaction case $\sigma=1$. For $\sigma > 4/3$ the transition is first
order, which includes the dipolar case $\sigma=3$. Another quantum critical
point separates the orientationally ordered (nematic) phase from a quantum
disordered phase for any value of $\sigma$. Critical exponents as a function of
$\sigma$ are computed at one loop order in an $\epsilon$ expansion and,
whenever available, compared with known results. For finite temperatures it is
found that for $\sigma \geq 2$ orientational order decays algebraically with
distance until a critical Kosterlitz-Thouless line. Nevertheless, for $\sigma <
2$ it is found that long range orientational order can exist at finite
temperatures until a critical line which terminates at the quantum critical
point at $T=0$. The temperature dependence of the critical line near the
quantum critical point is determined as a function of $\sigma$.


title:
Decoherence and pointer states in small antiferromagnets: A benchmark
  test

abstract:
  We study the decoherence process of a four spin-1/2 antiferromagnet that is
coupled to an environment of spin-1/2 particles. The preferred basis of the
antiferromagnet is discussed in two limiting cases and we identify two
$\it{exact}$ pointer states. Decoherence near the two limits is examined
whereby entropy is used to quantify the $\it{robustness}$ of states against
environmental coupling. We find that close to the quantum measurement limit,
the self-Hamiltonian of the system of interest can become dynamically relevant
on macroscopic timescales. We illustrate this point by explicitly constructing
a state that is more robust than (generic) states diagonal in the
system-environment interaction Hamiltonian.


title: Lecture Notes on Mathematical Methods of Classical Physics

abstract:
  These notes grew out of a lecture course on mathematical methods of classical
physics for students of mathematics and mathematical physics at the master's
level. Also, physicists with a strong interest in mathematics may find this
text useful as a resource complementary to existing textbooks on classical
physics. Topics include Lagrangian Mechanics, Hamiltonian Mechanics,
Hamilton-Jacobi Theory, as well as Classical Field Theory formulated in the
language of jet bundles. The latter topic also covers important examples of
field theories such as sigma models, gauge theory, and Einstein's theory of
general relativity.


title: Evaluating the Impact of AbuseHUB on Botnet Mitigation

abstract:
  This documents presents the final report of a two-year project to evaluate
the impact of AbuseHUB, a Dutch clearinghouse for acquiring and processing
abuse data on infected machines. The report was commissioned by the Netherlands
Ministry of Economic Affairs, a co-funder of the development of AbuseHUB.
AbuseHUB is the initiative of 9 Internet Service Providers, SIDN (the registry
for the .nl top-level domain) and Surfnet (the national research and education
network operator). The key objective of AbuseHUB is to improve the mitigation
of botnets by its members.
  We set out to assess whether this objective is being reached by analyzing
malware infection levels in the networks of AbuseHUB members and comparing them
to those of other Internet Service Providers (ISPs). Since AbuseHUB members
together comprise over 90 percent of the broadband market in the Netherlands,
it also makes sense to compare how the country as a whole has performed
compared to other countries. This report complements the baseline measurement
report produced in December 2013 and the interim report from March 2015. We are
using the same data sources as in the interim report, which is an expanded set
compared to the earlier baseline report and to our 2011 study into botnet
mitigation in the Netherlands.


title: Reduced Donaldson-Thomas invariants and the ring of dual numbers

abstract:
  Let $A$ be an abelian variety. We introduce $A$-equivariant Grothendieck
rings and $A$-equivariant motivic Hall algebras, and endow them with natural
integration maps to the ring of dual numbers. The construction allows a
systematic treatment of reduced Donaldson-Thomas invariants by Hall algebra
techniques. We calculate reduced Donaldson-Thomas invariants for $\mathrm{K3}
\times E$ and abelian threefolds for several imprimitive curve classes. This
verifies (in special cases) multiple cover formulas conjectured by
Oberdieck-Pandharipande and Bryan-Oberdieck-Pandharipande-Yin.


title:
A Systematic and Semi-Automatic Safety-Based Test Case Generation
  Approach Based on Systems-Theoretic Process Analysis

abstract:
  Software safety is a crucial aspect during the development of modern
safety-critical systems. Software is becoming responsible for most of the
critical functions of systems. Therefore, the software components in the
systems need to be tested extensively against their safety requirements to
ensure a high level of system safety. However, performing testing exhaustively
to test all software behaviours is impossible. Numerous testing approaches
exist. However, they do not directly concern the information derived during the
safety analysis. STPA (Systems-Theoretic Process Analysis) is a unique safety
analysis approach based on system and control theory, and was developed to
identify unsafe scenarios of a complex system including software. In this
paper, we present a systematic and semi-automatic testing approach based on
STPA to generate test cases from the STPA safety analysis results to help
software and safety engineers to recognize and reduce the associated software
risks. We also provide an open-source safety-based testing tool called STPA
TCGenerator to support the proposed approach. We illustrate the proposed
approach with a prototype of a software of the Adaptive Cruise Control System
(ACC) with a stop-and-go function with a Lego-Mindstorms EV3 robot.


title: Entropy evolution in the magnetic phases of partially frustrated CePdAl

abstract:
  In the heavy-fermion metal CePdAl long-range antiferromagnetic order coexists
with geometric frustration of one third of the Ce moments. At low temperatures
the Kondo effect tends to screen the frustrated moments. We use magnetic fields
$B$ to suppress the Kondo screening and study the magnetic phase diagram and
the evolution of the entropy with $B$ employing thermodynamic probes. We
estimate the frustration by introducing a definition of the frustration
parameter based on the enhanced entropy, a fundamental feature of frustrated
systems. In the field range where the Kondo screening is suppressed the
liberated moments tend to maximize the magnetic entropy and strongly enhance
the frustration. Based on our experiments, this field range may be a promising
candidate to search for a quantum spin liquid.


title: Integrability of a generalized short pulse equation revisited

abstract:
  We further generalize the generalized short pulse equation studied recently
in [Commun. Nonlinear Sci. Numer. Simulat. 39 (2016) 21-28; arXiv:1510.08822],
and find in this way two new integrable nonlinear wave equations which are
transformable to linear Klein-Gordon equations.


title:
Automorphism groups of countable structures and groups of measurable
  functions

abstract:
  Let $G$ be a topological group and let $\mu$ be the Lebesgue measure on the
interval $[0,1]$. We let $L_0(G)$ to be the topological group of all
$\mu$-equivalence classes of $\mu$-measurable functions defined on [0,1] with
values in $G$, taken with the pointwise multiplication and the topology of
convergence in measure. We show that for a Polish group $G$, if $L_0(G)$ has
ample generics, then $G$ has ample generics, thus the converse to a result of
Ka\"{i}chouh and Le Ma\^{i}tre.
  We further study topological similarity classes and conjugacy classes for
many groups ${\rm{Aut}}(M)$ and $L_0({\rm{Aut}}(M))$, where $M$ is a countable
structure. We make a connection between the structure of groups generated by
tuples, the Hrushovski property, and the structure of their topological
similarity classes. In particular, we prove the trichotomy that for every tuple
$ \bar{f}$ of ${\rm{Aut}}(M)$, where $M$ is a countable structure such that
algebraic closures of finite sets are finite, either the countable group
$\langle \bar{f} \rangle$ is precompact, or it is discrete, or the similarity
class of $\bar{f}$ is meager, in particular the conjugacy class of $\bar{f}$ is
meager. We prove an analogous trichotomy for groups $L_0({\rm{Aut}}(M))$.


title:
History of the mass ejection in K 4-37: from the AGB to the evolved
  planetary nebula phase

abstract:
  We present narrow-, broad-band, and WISE archive images, and high- and
intermediate-resolution long-slit spectra of K 4-37, a planetary nebula that
has never been analyzed in detail. Although K 4-37 appears bipolar, the
morphokinematical analysis discloses the existence of three distinct axes and
additional particular directions in the object, indicating that K 4-37 is a
multi-axis planetary nebula that has probably been shaped by several bipolar
outflows at different directions. A 4-6 M$_{\odot}$ main-sequence progenitor is
estimated from the derived high nebular He and N abundances, and very high N/O
abundance ratio ($\sim$2.32). The general properties are compatible with K 4-37
being a highly evolved planetary nebula located at $\sim$14 kpc. The WISE image
at 22 $\mu$m reveals K 4-37 to be surrounded by a large ($\sim$13$\times$8
pc$^2$) elliptical detached shell probably related to material ejected from the
AGB progenitor. The observed elliptical morphology suggests deformation of an
originally spherical AGB shell by the ISM magnetic field or by the influence of
a companion. We compare K 4-37 and NGC 6309 and found remarkable similarities
in their physical structure but noticeably different chemical abundances that
indicate very different progenitor mass. This strongly suggests that,
irrespective of the initial mass, their (presumably binary) central stars have
shared a very similar mass ejection history.


title: Low-rank matrix recovery via rank one tight frame measurements

abstract:
  The task of reconstructing a low rank matrix from incomplete linear
measurements arises in areas such as machine learning, quantum state tomography
and in the phase retrieval problem. In this note, we study the particular setup
that the measurements are taken with respect to rank one matrices constructed
from the elements of a random tight frame. We consider a convex optimization
approach and show both robustness of the reconstruction with respect to noise
on the measurements as well as stability with respect to passing to
approximately low rank matrices. This is achieved by establishing a version of
the null space property of the corresponding measurement map.


title:
A comprehensive safety engineering approach for software-intensive
  systems based on STPA

abstract:
  Formal verification and testing are complementary approaches which are used
in the development process to verify the functional correctness of software.
However, the correctness of software cannot ensure the safe operation of
safety-critical software systems. The software must be verified against its
safety requirements which are identified by safety analysis, to ensure that
potential hazardous causes cannot occur. The complexity of software makes
defining appropriate software safety requirements with traditional safety
analysis techniques difficult. STPA (Systems-Theoretic Processes Analysis) is a
unique safety analysis approach that has been developed to identify system
hazards, including the software-related hazards. This paper presents a
comprehensive safety engineering approach based on STPA, including software
testing and model checking approaches for the purpose of developing safe
software. The proposed approach can be embedded within a defined software
engineering process or applied to existing software systems, allow software and
safety engineers integrate the analysis of software risks with their
verification. The application of the proposed approach is illustrated with an
automotive software controller.


title:
Indirect Signals from Solar Dark Matter Annihilation to Long-lived
  Right-handed Neutrinos

abstract:
  We study indirect detection signals from solar annihilation of dark matter
(DM) particles into light right-handed (RH) neutrinos with a mass in a $1-5$
GeV range. These RH neutrinos can have a sufficiently long lifetime to allow
them to decay outside the Sun and their delayed decays can result in a signal
in gamma rays from the otherwise `dark' solar direction, and also a neutrino
signal that is not suppressed by the interactions with solar medium. We find
that the latest Fermi-LAT and IceCube results place limits on the gamma ray and
neutrino signals, respectively. Combined photon and neutrino bounds can
constrain the spin-independent DM-nucleon elastic scattering cross section
better than direct detection experiments for DM masses from 200 GeV up to
several TeV. The bounds on spin-dependent scattering are also much tighter than
the strongest limits from direct detection experiments.


title: Discriminating Z' signals in semileptonic top pair production at the LHC

abstract:
  We investigate the sensitivity of top pair production to the properties of
different Beyond the Standard Model theories embedding a new neutral boson. We
include six-fermion decay, and account for the full tree-level Standard Model
ttbar interference, with all intermediate particles allowed off-shell. We focus
on those observables best suited to the lepton-plus-jets final state at the
LHC, and simulate the resulting experimental conditions, including kinematic
requirements and top quark pair reconstruction in the presence of missing
transverse energy and combinatorial ambiguity in quark-top assignment. In
particular, we demonstrate the use of asymmetry observables to probe the
coupling structure of a new neutral resonance, in addition to cases in which
these asymmetries may even form complementary discovery observables in
combination with the differential cross section.


title: Spectrally arbitrary pattern extensions

abstract:
  A matrix pattern is often either a sign pattern with entries in {0,+,-} or,
more simply, a nonzero pattern with entries in {0,*}. A matrix pattern A is
spectrally arbitrary if for any choice of a real matrix spectrum, there is a
real matrix having the pattern A and the chosen spectrum. We describe a
graphical technique, a triangle extension, for constructing spectrally
arbitrary patterns out of some known lower order spectrally arbitrary patterns.
These methods provide a new way of viewing some known spectrally arbitrary
patterns, as well as providing many new families of spectrally arbitrary
patterns. We also demonstrate how the technique can be applied to certain
inertially arbitrary patterns to obtain larger inertially arbitrary patterns.
We then provide an additional extension method for zero-nonzero patterns.


title: Minisuperspace quantization of bubbling AdS$_2\times$S$^2$ geometries

abstract:
  We quantize the moduli space of supersymmetric microstates describing
four-dimensional black holes with AdS$_2$$\times$S$^2$ asymptotics. To acquire
the commutation relations of quantization, we find the symplectic form that is
imposed in the Type IIB SUGRA and defined in the space of solutions
parameterized by one complex harmonic function in ${R}^3$ with sources
distributed along closed curves.


title:
Brownian Motion and Finite Approximations of Quantum Systems over Local
  Fields

abstract:
  We give a stochastic proof of the finite approximability of a class of
Schr\"odinger operators over a local field, thereby completing a program of
establishing in a non-Archimedean setting corresponding results and methods
from the Archimedean (real) setting. A key ingredient of our proof is to show
that Brownian motion over a local field can be obtained as a limit of random
walks over finite grids. Also, we prove a Feynman-Kac formula for the finite
systems, and show that the propagator at the finite level converges to the
propagator at the infinite level.


title: Constraints and Entropy in a Model of Network Evolution

abstract:
  Barab\'asi-Albert's `Scale Free' model is the starting point for much of the
accepted theory of the evolution of real world communication networks. Careful
comparison of the theory with a wide range of real world networks, however,
indicates that the model is in some cases, only a rough approximation to the
dynamical evolution of real networks. In particular, the exponent $\gamma$ of
the power law distribution of degree is predicted by the model to be exactly 3,
whereas in a number of real world networks it has values between 1.2 and 2.9.
In addition, the degree distributions of real networks exhibit cut offs at high
node degree, which indicates the existence of maximal node degrees for these
networks. In this paper we propose a simple extension to the `Scale Free'
model, which offers better agreement with the experimental data. This
improvement is satisfying, but the model still does not explain \emph{why} the
attachment probabilities should favor high degree nodes, or indeed how
constraints arrive in non-physical networks. Using recent advances in the
analysis of the entropy of graphs at the node level we propose a first
principles derivation for the `Scale Free' and `constraints' model from
thermodynamic principles, and demonstrate that both preferential attachment and
constraints could arise as a natural consequence of the second law of
thermodynamics.


title:
Arithmetic of commutative semigroups with a focus on semigroups of
  ideals and modules

abstract:
  Let $H$ be a commutative semigroup with unit element such that every non-unit
can be written as a finite product of irreducible elements (atoms). For every
$k \in \mathbb N$, let $\mathscr U_k (H)$ denote the set of all $\ell \in
\mathbb N$ with the property that there are atoms $u_1, \ldots, u_k, v_1,
\ldots, v_{\ell}$ such that $u_1 \cdot \ldots \cdot u_k = v_1 \cdot \ldots
\cdot v_{\ell}$ (thus, $\mathscr U_k (H)$ is the union of all sets of lengths
containing $k$).
  The Structure Theorem for Unions states that, for all sufficiently large $k$,
the sets $\mathscr U_k (H)$ are almost arithmetical progressions with the same
difference and global bound. We present a new approach to this result in the
framework of arithmetic combinatorics, by deriving, for suitably defined
families of subsets of the non-negative integers, a characterization of when
the Structure Theorem holds.
  This abstract approach allows us to verify, for the first time, the Structure
Theorem for a variety of possibly non-cancellative semigroups, including
semigroups of (not necessarily invertible) ideals and semigroups of modules.
Furthermore, we provide the very first example of a semigroup (actually, a
locally tame Krull monoid) that does not satisfy the Structure Theorem.


title:
Advancing Bayesian Optimization: The Mixed-Global-Local (MGL) Kernel and
  Length-Scale Cool Down

abstract:
  Bayesian Optimization (BO) has become a core method for solving expensive
black-box optimization problems. While much research focussed on the choice of
the acquisition function, we focus on online length-scale adaption and the
choice of kernel function. Instead of choosing hyperparameters in view of
maximum likelihood on past data, we propose to use the acquisition function to
decide on hyperparameter adaptation more robustly and in view of the future
optimization progress. Further, we propose a particular kernel function that
includes non-stationarity and local anisotropy and thereby implicitly
integrates the efficiency of local convex optimization with global Bayesian
optimization. Comparisons to state-of-the art BO methods underline the
efficiency of these mechanisms on global optimization benchmarks.


title: Globally Irreducible Weyl Modules for Quantum Groups

abstract:
  The authors proved that a Weyl module for a simple algebraic group is
irreducible over every field if and only if the module is isomorphic to the
adjoint representation for $E_{8}$ or its highest weight is minuscule. In this
paper, we prove an analogous criteria for irreducibility of Weyl modules over
the quantum group $U_{\zeta}({\mathfrak g})$ where ${\mathfrak g}$ is a complex
simple Lie algebra and $\zeta$ ranges over roots of unity.


title: The Equivariant Second Yamabe Constant

abstract:
  For a closed Riemannian manifold of dimension $n\geq 3$ and a subgroup $G$ of
the isometry group, we define and study the $G-$equivariant second Yamabe
constant and we obtain some results on the existence of $G-$invariant nodal
solutions of the Yamabe equation.


title:
A Fock space model for decomposition numbers for quantum groups at roots
  of unity

abstract:
  In this paper we construct an "abstract Fock space" for general Lie types
that serves as a generalisation of the infinite wedge $q$-Fock space familiar
in type $A$. Specifically, for each positive integer $\ell$, we define a
$\mathbb{Z}[q,q^{-1}]$-module $\mathcal{F}_{\ell}$ with bar involution by
specifying generators and "straightening relations" adapted from those
appearing in the Kashiwara-Miwa-Stern formulation of the $q$-Fock space. By
relating $\mathcal{F}_{\ell}$ to the corresponding affine Hecke algebra we show
that the abstract Fock space has standard and canonical bases for which the
transition matrix produces parabolic affine Kazhdan-Lusztig polynomials. This
property and the convenient combinatorial labeling of bases of
$\mathcal{F}_{\ell}$ by dominant integral weights makes $\mathcal{F}_{\ell}$ a
useful combinatorial tool for determining decomposition numbers of Weyl modules
for quantum groups at roots of unity.


title: Integrated Cosmological Probes: Extended Analysis

abstract:
  Recent progress in cosmology has relied on combining different cosmological
probes. In earlier work, we implemented an integrated approach to cosmology
where the probes are combined into a common framework at the map level. This
has the advantage of taking full account of the correlations between the
different probes, to provide a stringent test of systematics and of the
validity of the cosmological model. We extend this analysis to include not only
CMB temperature, galaxy clustering, weak lensing from SDSS but also CMB
lensing, weak lensing from the DES SV survey, Type Ia SNe and $H_{0}$
measurements. This yields 12 auto- and cross-power spectra as well as
background probes. Furthermore, we extend the treatment of systematic
uncertainties. For $\Lambda$CDM, we find results that are consistent with our
earlier work. Given our enlarged data set and systematics treatment, this
confirms the robustness of our analysis and results. Furthermore, we find that
our best-fit cosmological model gives a good fit to the data we consider with
no signs of tensions within our analysis. We also find our constraints to be
consistent with those found by WMAP9, SPT and ACT and the KiDS weak lensing
survey. Comparing with the Planck Collaboration results, we see a broad
agreement, but there are indications of a tension from the marginalized
constraints in most pairs of cosmological parameters. Since our analysis
includes CMB temperature Planck data at $10 < \ell < 610$, the tension appears
to arise between the Planck high$-\ell$ and the other measurements.
Furthermore, we find the constraints on the probe calibration parameters to be
in agreement with expectations, showing that the data sets are mutually
consistent. In particular, this yields a confirmation of the amplitude
calibration of the weak lensing measurements from SDSS, DES SV and Planck CMB
lensing from our integrated analysis. [abridged]


title:
Non-Perturbative Renormalization Group for the Diffusive Epidemic
  Process

abstract:
  We consider the Diffusive Epidemic Process (DEP), a two-species
reaction-diffusion process originally proposed to model disease spread within a
population. This model exhibits a phase transition from an active epidemic to
an absorbing state without sick individuals. Field-theoretic analyses suggest
that this transition belongs to the universality class of Directed Percolation
with a Conserved quantity (DP-C). However, some exact predictions derived from
the symmetries of DP-C seem to be in contradiction with lattice simulations.
Here we revisit the field theory of both DP-C and DEP. We discuss in detail the
symmetries present in the various formulations of both models, some of which
had not been identified previously. We then investigate the DP-C model using
the derivative expansion of the non-perturbative renormalization group
formalism. We recover previous results for DP-C near its upper critical
dimension $d_c=4$, but show how the corresponding fixed point seems to no
longer exist below $d \lesssim 3$. Consequences for the DEP universality class
are considered.


title: Clogging and Jamming Transitions in Periodic Obstacle Arrays

abstract:
  We numerically examine clogging transitions for bidisperse disks flowing
through a two dimensional periodic obstacle array. We show that clogging is a
probabilistic event that occurs through a transition from a homogeneous flowing
state to a heterogeneous or phase separated jammed state where the disks form
dense connected clusters. The probability for clogging to occur during a fixed
time increases with increasing particle packing and obstacle number. For
driving at different angles with respect to the symmetry direction of the
obstacle array, we show that certain directions have a higher clogging
susceptibility. It is also possible to have a size-specific clogging transition
in which one disk size becomes completely immobile while the other disk size
continues to flow.


title: An ultraweak DPG method for viscoelastic fluids

abstract:
  We explore a vexing benchmark problem for viscoelastic fluid flows with the
discontinuous Petrov-Galerkin (DPG) finite element method of Demkowicz and
Gopalakrishnan [1,2]. In our analysis, we develop an intrinsic a posteriori
error indicator which we use for adaptive mesh generation. The DPG method is
useful for the problem we consider because the method is inherently
stable---requiring no stabilization of the linearized discretization in order
to handle the advective terms in the model. Because stabilization is a pressing
issue in these models, this happens to become a very useful property of the
method which simplifies our analysis. This built-in stability at all length
scales and the a posteriori error indicator additionally allows for the
generation of parameter-specific meshes starting from a common coarse initial
mesh. A DPG discretization always produces a symmetric positive definite
stiffness matrix. This feature allows us to use the most efficient direct
solvers for all of our computations. We use the Camellia finite element
software package [3,4] for all of our analysis.


title: Paradoxes in Leaky Microbial Trade

abstract:
  Microbes produce metabolic resources that are important for cell growth yet
leak across membranes into the extracellular environment. Other microbes in the
same environment can use these resources and adjust their own metabolic
production accordingly---causing other resources to leak into the environment.
The combined effect of these processes is an economy in which organismal growth
and metabolic production are coupled to others in the community. We propose a
model for the co-evolving dynamics of metabolite concentrations, production
regulation, and population frequencies for the case of two cell types, each
requiring and capable of producing two metabolites. In this model, beneficial
trade relations emerge without any coordination, via individual-level
production decisions that maximize each cell's growth rate given its perceived
environment. As we vary production parameters of the model, we encounter three
paradoxical behaviors, where a change that should intuitively benefit some cell
type, actually harms it. (1) If a cell type is more efficient than its
counterpart at producing a metabolite and becomes even more efficient, its
frequency in the population can decrease. (2) If a cell type is less efficient
than its counterpart at producing a metabolite but becomes less inefficient,
the growth rate of the population can decrease. (3) Finally, if a cell type
controls its counterpart's production decisions so as to maximize its own
growth rate, the ultimate growth rate it achieves can be lower than if the two
cell types each maximized their own growth. These three paradoxes highlight the
complex and counter-intuitive dynamics that emerge in simple microbial
economies.


title:
Ab Initio Velocity-Field Curves in Monoclinic
  \(\beta\)-Ga\textsubscript{2}O\textsubscript{3}}

abstract:
  We investigate the high-field transport in monoclinic
\(\beta\)-Ga\textsubscript{2}O\textsubscript{3}} using a combination of ab
initio calculations and full band Monte Carlo (FBMC) simulation. Scattering
rate calculation and the final state selection in the FBMC simulation use
complete wave-vector (both electron and phonon) and crystal direction dependent
electron phonon interaction (EPI) elements. We propose and implement a
semi-coarse version of the Wannier-Fourier interpolation method [F. Giustino,
M. L. Cohen, and S. G. Louie, Physical Review B, vol. 76, no. 16, 2007] for
short-range non-polar optical phonon (EPI) elements in order to ease the
computational requirement in FBMC simulation. During the interpolation of the
EPI, the inverse Fourier sum over the real-space electronic grids is done on a
coarse mesh while the unitary rotations are done on a fine mesh. This paper
reports the high field transport in monoclinic
\(\beta\)-Ga\textsubscript{2}O\textsubscript{3}} with deep insight on the
contribution of electron-phonon interactions, and velocity-field
characteristics for electric fields ranging up to 450 kV/cm in different
crystal directions. A peak velocity of $2\times10^{7}& cm/s is estimated at an
electric field of 200 kV/cm.


title: Birds of a feather or opposites attract - effects in network modelling

abstract:
  We study properties of some standard network models when the population is
split into two types and the connection pattern between the types is varied.
The studied models are generalizations of the Erd\H{o}s-R\'{e}nyi graph, the
configuration model and a preferential attachment graph. For the
Erd\H{o}s-R\'{e}nyi graph and the configuration model, the focus is on the
component structure. We derive expressions for the critical parameter,
indicating when there is a giant component in the graph, and study the size of
the largest component by aid of simulations. When the expected degrees in the
graph are fixed and the connections are shifted so that more edges connect
vertices of different types, we find that the critical parameter decreases. The
size of the largest component in the supercritical regime can be both
increasing and decreasing as the connections change, depending on the
combination of types. For the preferential attachment model, we analyze the
degree distributions of the two types and derive explicit expressions for the
degree exponents. The exponents are confirmed by simulations that also
illustrate other properties of the degree structure.


title:
$\Gamma$-convergence analysis of a generalized $XY$ model: fractional
  vortices and string defects

abstract:
  We propose and analyze a generalized two dimensional $XY$ model, whose
interaction potential has $n$ weighted wells, describing corresponding
symmetries of the system. As the lattice spacing vanishes, we derive by
$\Gamma$-convergence the discrete-to-continuum limit of this model. In the
energy regime we deal with, the asymptotic ground states exhibit fractional
vortices, connected by string defects. The $\Gamma$-limit takes into account
both contributions, through a renormalized energy, depending on the
configuration of fractional vortices, and a surface energy, proportional to the
length of the strings.
  Our model describes in a simple way several topological singularities arising
in Physics and Materials Science. Among them, disclinations and string defects
in liquid crystals, fractional vortices and domain walls in micromagnetics,
partial dislocations and stacking faults in crystal plasticity.


title: Boundary-aware Instance Segmentation

abstract:
  We address the problem of instance-level semantic segmentation, which aims at
jointly detecting, segmenting and classifying every individual object in an
image. In this context, existing methods typically propose candidate objects,
usually as bounding boxes, and directly predict a binary mask within each such
proposal. As a consequence, they cannot recover from errors in the object
candidate generation process, such as too small or shifted boxes.
  In this paper, we introduce a novel object segment representation based on
the distance transform of the object masks. We then design an object mask
network (OMN) with a new residual-deconvolution architecture that infers such a
representation and decodes it into the final binary object mask. This allows us
to predict masks that go beyond the scope of the bounding boxes and are thus
robust to inaccurate object candidates. We integrate our OMN into a Multitask
Network Cascade framework, and learn the resulting boundary-aware instance
segmentation (BAIS) network in an end-to-end manner. Our experiments on the
PASCAL VOC 2012 and the Cityscapes datasets demonstrate the benefits of our
approach, which outperforms the state-of-the-art in both object proposal
generation and instance segmentation.


title:
A General Theory for Bandgap Estimation in Locally Resonant
  Metastructures

abstract:
  Locally resonant metamaterials are characterized by bandgaps at wavelengths
that are much larger than the lattice size, enabling low-frequency vibration
attenuation. Typically, bandgap analyses and predictions rely on the assumption
of traveling waves in an infinite medium, and do not take advantage of modal
representations typically used for the analysis of the dynamic behavior of
finite structures. Recently, we developed a method for understanding the
locally resonant bandgap in uniform finite metamaterial beams using modal
analysis. Here we extend that framework to general locally resonant
metastructures with specified boundary conditions using a general operator
formulation. Using this approach, along with the assumption of an infinite
number of resonators tuned to the same frequency, the frequency range of the
locally resonant bandgap is easily derived in closed form. Furthermore, the
bandgap expression is shown to be the same regardless of the type of vibration
problem under consideration, depending only on the added mass ratio and target
frequency. It is shown that the number of resonators required for the bandgap
to appear increases with the target frequency range, i.e. respective modal
neighborhood. Furthermore, it is observed that there is an optimal, finite
number of resonators which gives a bandgap that is wider than the
infinite-absorber bandgap, and that the optimal number of resonators increases
with target frequency and added mass ratio. As the number of resonators becomes
sufficiently large, the bandgap converges to the derived infinite-absorber
bandgap. The derived bandgap edge frequencies are shown to agree with results
from dispersion analysis using the plane wave expansion method. Numerical and
experimental investigations are performed regarding the effects of mass ratio,
non-uniform spacing of resonators, and parameter variations among the
resonators.


title:
Frequency-encoded photonic qubits for scalable quantum information
  processing

abstract:
  Among the objectives toward large-scale quantum computation is the quantum
interconnect: a device which uses photons to interface qubits that otherwise
could not interact. However, current approaches require photons
indistinguishable in frequency---a major challenge for systems experiencing
different local environments or of different physical compositions altogether.
Here we develop an entirely new platform which actually exploits such frequency
mismatch for processing quantum information. Labeled "spectral linear optical
quantum computation" (spectral LOQC), our protocol offers favorable linear
scaling of optical resources and enjoys an unprecedented degree of parallelism,
as an arbitrary $N$-qubit quantum gate may be performed in parallel on multiple
$N$-qubit sets in the same linear optical device. Not only does spectral LOQC
offer new potential for optical interconnects; it also brings the ubiquitous
technology of high-speed fiber optics to bear on photonic quantum information,
making wavelength-configurable and robust optical quantum systems within reach.


title: Phase transitions in Restricted Boltzmann Machines with generic priors

abstract:
  We study Generalised Restricted Boltzmann Machines with generic priors for
units and weights, interpolating between Boolean and Gaussian variables. We
present a complete analysis of the replica symmetric phase diagram of these
systems, which can be regarded as Generalised Hopfield models. We underline the
role of the retrieval phase for both inference and learning processes and we
show that retrieval is robust for a large class of weight and unit priors,
beyond the standard Hopfield scenario. Furthermore we show how the paramagnetic
phase boundary is directly related to the optimal size of the training set
necessary for good generalisation in a teacher-student scenario of unsupervised
learning.

categories: cond-mat.dis-nn cs.LG physics.data-an stat.ML


title: Topological Complexity of the Klein bottle

abstract:
  We show that the (normalized) topological complexity of the Klein bottle is
$4$. We also show that, for any $g\geq 2$, $TC(N_g)=4$. This completes the
recent work by Dranishnikov on the topological complexity of non-orientable
surfaces.


title: "Inchworm Filaments": Motility and Pattern Formation

abstract:
  In a previous paper, we examined a class of possible conformations for
helically patterned filaments in contact with a bonding surface. In particular,
we investigated geometries where contact between the pattern and the surface
was improved through a periodic twisting and lifting of the filament. A
consequence of this lifting is that the total length of the filament projected
onto the surface decreases after bonding. When the bonding character of the
surface is actuated, this phenomenon can lead to both lifelike "inchworm"
behavior of the filaments and ensemble movement. We illustrate, through
simulation, how pattern formation may be achieved through this mechanism.


title:
Close binary progenitors and ejected companions of thermonuclear
  supernovae

abstract:
  Hot subdwarf stars (sdO/Bs) are evolved core helium-burning stars with very
thin hydrogen envelopes, which can be formed by common envelope ejection. Close
sdB binaries with massive white dwarf (WD) companions are potential progenitors
of thermonuclear supernovae type Ia (SN~Ia). We discovered such a progenitor
candidate as well as a candidate for a surviving companion star, which escapes
from the Galaxy. More candidates for both types of objects have been found by
crossmatching known sdB stars with proper motion and light curve catalogues. We
found 72 sdO/B candidates with high Galactic restframe velocities, 12 of them
might be unbound to our Galaxy. Furthermore, we discovered the second-most
compact sdB+WD binary known. However, due to the low mass of the WD companion,
it is unlikely to be a SN\,Ia progenitor.


title:
Finite Ramanujan expansions and shifted convolution sums of arithmetical
  functions

abstract:
  For two arithmetical functions $f$ and $g$, we study the convolution sum of
the form $\sum_{n \le N} f(n) g(n+h)$ in the context of its asymptotic formula
with explicit error terms. Here we introduce the concept of finite Ramanujan
expansion of an arithmetical function and extend our earlier works in this
setup.


title: The status of the strong coupling from tau decays in 2016

abstract:
  While the idea of using the operator product expansion (OPE) to extract the
strong coupling from hadronic $\tau$ decay data is not new, there is an ongoing
controversy over how to include quark-hadron "duality violations" (i.e.,
resonance effects) which are not described by the OPE. One approach attempts to
suppress duality violations enough that they might become negligible, but pays
the price of an uncontrolled OPE truncation. We critically examine a recent
analysis using this approach and show that it fails to properly account for
non-perturbative effects, making the resulting determination of the strong
coupling unreliable. In a different approach duality violations are taken into
account with a model, avoiding the OPE truncation. This second approach
provides a self-consistent determination of the strong coupling from $\tau$
decays.


title: Action of Automorphisms on Irreducible Characters of Symplectic Groups

abstract:
  Assume $G$ is a finite symplectic group $\mathrm{Sp}_{2n}(q)$ over a finite
field $\mathbb{F}_q$ of odd characteristic. We describe the action of the
automorphism group $\mathrm{Aut}(G)$ on the set $\mathrm{Irr}(G)$ of ordinary
irreducible characters of $G$. This description relies on the equivariance of
Deligne--Lusztig induction with respect to automorphisms. We state a version of
this equivariance which gives a precise way to compute the automorphism on the
corresponding Levi subgroup; this may be of independent interest. As an
application we prove that the global condition in Sp\"ath's criterion for the
inductive McKay condition holds for the irreducible characters of
$\mathrm{Sp}_{2n}(q)$.


title: Instability of an integrable nonlocal NLS

abstract:
  In this note we discuss the global dynamics of an integrable nonlocal NLS on
$\mathbb{R}$, which has been the object of recent investigation by integrable
systems methods. We prove two results which are in striking contrast with the
case of the local cubic focusing NLS on $\mathbb{R}$. First, finite time
blow-up solutions exist with arbitrarily small initial data in
$H^s(\mathbb{R})$, for any $s\geqslant0$. On the other hand, the solitons of
the local NLS, which are also solutions of the nonlocal equation, are unstable
by blow-up for the latter.


title: An Efficient Algorithm for Monitoring Practical TPTL Specifications

abstract:
  We provide a dynamic programming algorithm for the monitoring of a fragment
of Timed Propositional Temporal Logic (TPTL) specifications. This fragment of
TPTL, which is more expressive than Metric Temporal Logic, is characterized by
independent time variables which enable the elicitation of complex real-time
requirements. For this fragment, we provide an efficient polynomial time
algorithm for off-line monitoring of finite traces. Finally, we provide
experimental results on a prototype implementation of our tool in order to
demonstrate the feasibility of using our tool in practical applications.


title: Dimension theory and degenerations of de Jonqui\`eres divisors

abstract:
  This paper aims at settling the issue of the validity of the de Jonqui\`eres
formulas. We consider the space of divisors with prescribed multiplicity, or de
Jonqui\`eres divisors, contained in a linear series on a smooth projective
curve. Assuming zero expected dimension of this space, the de Jonqui\`eres
formulas compute the virtual number of de Jonqui\`eres divisors. Using
degenerations to nodal curves we show that for a general curve equipped with a
general complete linear series, the space is of expected dimension, which shows
that the counts are in fact true. This implies that in the case of negative
expected dimension a general linear series on a general curve does not admit de
Jonqui\`eres divisors of the expected type.


title: Understanding and Mapping Natural Beauty

abstract:
  While natural beauty is often considered a subjective property of images, in
this paper, we take an objective approach and provide methods for quantifying
and predicting the scenicness of an image. Using a dataset containing hundreds
of thousands of outdoor images captured throughout Great Britain with
crowdsourced ratings of natural beauty, we propose an approach to predict
scenicness which explicitly accounts for the variance of human ratings. We
demonstrate that quantitative measures of scenicness can benefit semantic image
understanding, content-aware image processing, and a novel application of
cross-view mapping, where the sparsity of ground-level images can be addressed
by incorporating unlabeled overhead images in the training and prediction
steps. For each application, our methods for scenicness prediction result in
quantitative and qualitative improvements over baseline approaches.


title:
Increasing Modal Instabilities Threshold Through Bidirectional Pumping
  In High Power Fiber Amplifiers

abstract:
  In this letter, the impact of pump configuration on the modal instabilities
(MI) threshold of high power fiber amplifiers is investigated. Using a time
dependent computer model based on the optical beam propagation method (BPM),
the effect of bidirectional pumping on the MI threshold of high power fiber
amplifiers is explored and compared to that of a co-pumped configuration.
Simulation results indicate that the bidirectional pumping increases the
instabilities threshold by a factor of 30% with respect to the co-pumped
scheme. We attribute this threshold enhancement to a weaker strength of the
temperature induced refractive index grating due to a more homogeneous pump
profile along the fiber length. This technique demonstrates that the
engineering pump scheme is a promising approach leading to an appreciable
threshold enhancement of fiber amplifiers designed for high power applications.


title: Feature Pyramid Networks for Object Detection

abstract:
  Feature pyramids are a basic component in recognition systems for detecting
objects at different scales. But recent deep learning object detectors have
avoided pyramid representations, in part because they are compute and memory
intensive. In this paper, we exploit the inherent multi-scale, pyramidal
hierarchy of deep convolutional networks to construct feature pyramids with
marginal extra cost. A top-down architecture with lateral connections is
developed for building high-level semantic feature maps at all scales. This
architecture, called a Feature Pyramid Network (FPN), shows significant
improvement as a generic feature extractor in several applications. Using FPN
in a basic Faster R-CNN system, our method achieves state-of-the-art
single-model results on the COCO detection benchmark without bells and
whistles, surpassing all existing single-model entries including those from the
COCO 2016 challenge winners. In addition, our method can run at 5 FPS on a GPU
and thus is a practical and accurate solution to multi-scale object detection.
Code will be made publicly available.


title:
CH as a Molecular Gas Tracer and C-Shock Tracer Across a Molecular Cloud
  Boundary in Taurus

abstract:
  We present new observations of all three ground-state transitions of the
methylidyne (CH) radical and all four ground-state transitions of the hydroxyl
(OH) radical toward a sharp boundary region of the Taurus molecular cloud.
These data were analyzed in conjunction with existing CO and dust images. The
derived CH abundance is consistent with previous observations of translucent
clouds ($0.8\le A_{v} \le 2.1$ mag). The $X({\rm CH})$-factor is nearly a
constant at $(1.0\pm0.06)\times 10^{22}$ $\rm {cm^{-2}~K^{-1}~km^{-1}~s}$ in
this extinction range, with less dispersion than that of the more widely used
molecular tracers CO and OH. CH turns out be a better tracer of total column
density in such an intermediate extinction range than CO or OH. Compared with
previous observations, CH is overabundant below 1 mag extinction. Such an
overabundance of CH is consistent with the presence of a C-shock. CH has two
kinematic components, one of which shifts from 5.3 to 6 km s$^{-1}$, while the
other stays at 6.8 km s$^{-1}$ when moving from outside toward inside of the
cloud. These velocity behaviors exactly match with previous OH observation. The
shifting of the two kinematic components indicates colliding streams or gas
flow at the boundary region, which could be the cause of the C-shock.


title:
Scattering and Absorption Control in Biocompatible Fibers towards
  Equalized Photobiomodulation

abstract:
  Transparent tissue scaffolds enable illumination of growing tissue to
accelerate cell proliferation and improve other cell functions through
photobiomodulation. The biphasic dose response of cells exposed to
photobiomodulating light dictates that the illumination to be evenly
distributed across the scaffold such that the cells are neither under nor over
exposed to light. However, equalized illumination has not been sufficiently
addressed. Here we analyze and experimentally demonstrate spatially equalizing
illumination by three methods, namely, engineered surface scattering,
reflection by a gold mirror, and traveling-waves in a ring mesh. Our results
show that nearly equalized illumination is achievable by controlling the light
scattering-to-loss ratio. This demonstration opens opportunities for
dose-optimized photobiomodulation in tissue regeneration.


title: Testing Ising Models

abstract:
  Given samples from an unknown multivariate distribution $p$, is it possible
to distinguish whether $p$ is the product of its marginals versus $p$ being far
from every product distribution? Similarly, is it possible to distinguish
whether $p$ equals a given distribution $q$ versus $p$ and $q$ being far from
each other? These problems of testing independence and goodness-of-fit have
received enormous attention in statistics, information theory, and theoretical
computer science, with sample-optimal algorithms known in several interesting
regimes of parameters. Unfortunately, it has also been understood that these
problems become intractable in large dimensions, necessitating exponential
sample complexity.
  Motivated by the exponential lower bounds for general distributions as well
as the ubiquity of Markov Random Fields (MRFs) in the modeling of
high-dimensional distributions, we initiate the study of distribution testing
on structured multivariate distributions, and in particular the prototypical
example of MRFs: the Ising Model. We demonstrate that, in this structured
setting, we can avoid the curse of dimensionality, obtaining sample and time
efficient testers for independence and goodness-of-fit. One of the key
technical challenges we face along the way is bounding the variance of
functions of the Ising model.

categories: cs.DS cs.IT cs.LG math.IT math.PR math.ST stat.TH


title: Optimal mean-based algorithms for trace reconstruction

abstract:
  In the (deletion-channel) trace reconstruction problem, there is an unknown
$n$-bit source string $x$. An algorithm is given access to independent traces
of $x$, where a trace is formed by deleting each bit of~$x$ independently with
probability~$\delta$. The goal of the algorithm is to recover~$x$ exactly (with
high probability), while minimizing samples (number of traces) and running
time.
  Previously, the best known algorithm for the trace reconstruction problem was
due to Holenstein~et~al.; it uses $\exp(\tilde{O}(n^{1/2}))$ samples and
running time for any fixed $0 < \delta < 1$. It is also what we call a
"mean-based algorithm", meaning that it only uses the empirical means of the
individual bits of the traces. Holenstein~et~al.~also gave a lower bound,
showing that any mean-based algorithm must use at least $n^{\tilde{\Omega}(\log
n)}$ samples.
  In this paper we improve both of these results, obtaining matching upper and
lower bounds for mean-based trace reconstruction. For any constant deletion
rate $0 < \delta < 1$, we give a mean-based algorithm that uses
$\exp(O(n^{1/3}))$ time and traces; we also prove that any mean-based algorithm
must use at least $\exp(\Omega(n^{1/3}))$ traces. In fact, we obtain matching
upper and lower bounds even for $\delta$ subconstant and $\rho := 1-\delta$
subconstant: when $(\log^3 n)/n \ll \delta \leq 1/2$ the bound is
$\exp(-\Theta(\delta n)^{1/3})$, and when $1/\sqrt{n} \ll \rho \leq 1/2$ the
bound is $\exp(-\Theta(n/\rho)^{1/3})$.
  Our proofs involve estimates for the maxima of Littlewood polynomials on
complex disks. We show that these techniques can also be used to perform trace
reconstruction with random insertions and bit-flips in addition to deletions.
We also find a surprising result: for deletion probabilities $\delta > 1/2$,
the presence of insertions can actually help with trace reconstruction.


title:
Multiple phase separation in one-dimensional mixtures of mass- and
  population-imbalanced attractive Fermi gases

abstract:
  We study the attractive Fermi mixture of a
${}^{6}\mathrm{Li}$-${}^{40}\mathrm{K}$ gas in one dimension using the
continuous matrix product states variational ansatz and obtain the $T=0$ phase
diagram. We predict an axial density profile that contains four distinct phases
trapped induced along one-dimensional (1D) tubes, which is more intricate than
those observed in 1D mass-balanced systems or in higher-dimensional gas clouds.
The parameter regimes explored are realistic in view of possible future
experiments. This an application of continuous matrix product states to a
nonintegrable fermionic system.


title: Budget Feasible Mechanisms on Matroids

abstract:
  Motivated by many practical applications, in this paper we study {\em budget
feasible mechanisms} where the goal is to procure independent sets from
matroids. More specifically, we are given a matroid
$\mathcal{M}=(E,\mathcal{I})$ where each ground (indivisible) element is a
selfish agent. The cost of each element (i.e., for selling the item or
performing a service) is only known to the element itself. There is a buyer
with a budget having additive valuations over the set of elements $E$. The goal
is to design an incentive compatible (truthful) budget feasible mechanism which
procures an independent set of the matroid under the given budget that yields
the largest value possible to the buyer. Our result is a deterministic,
polynomial-time, individually rational, truthful and budget feasible mechanism
with $4$-approximation to the optimal independent set. Then, we extend our
mechanism to the setting of matroid intersections in which the goal is to
procure common independent sets from multiple matroids. We show that, given a
polynomial time deterministic blackbox that returns $\alpha-$approximation
solutions to the matroid intersection problem, there exists a deterministic,
polynomial time, individually rational, truthful and budget feasible mechanism
with $(3\alpha +1)-$approximation to the optimal common independent set.


title: Stabilisation of semilocal strings by dark scalar condensates

abstract:
  Semilocal and electroweak strings are well-known to be unstable against
unwinding by the condensation of the second Higgs component in their cores. A
large class of current models of dark matter contains dark scalar fields
coupled to the Higgs sector of the Standard Model (Higgs portal) and/or dark
U(1) gauge fields. It is shown, that Higgs-portal-type couplings and a gauge
kinetic mixing term of the dark U(1) gauge field have a significant stabilising
effect on semilocal strings in the "visible" sector.


title: Optimized Execution of Business Processes on Blockchain

abstract:
  Blockchain technology enables the execution of collaborative business
processes involving untrusted parties without requiring a central authority.
Specifically, a process model comprising tasks performed by multiple parties
can be coordinated via smart contracts operating on the blockchain. The
consensus mechanism governing the blockchain thereby guarantees that the
process model is followed by each party. However, the cost required for
blockchain use is highly dependent on the volume of data recorded and the
frequency of data updates by smart contracts. This paper proposes an optimized
method for executing business processes on top of commodity blockchain
technology. The paper presents a method for compiling a process model into a
smart contract that encodes the preconditions for executing each task in the
process using a space-optimized data structure. The method is empirically
compared to a previously proposed baseline by replaying execution logs,
including one from a real-life business process, and measuring resource
consumption.


title:
Panoptic Studio: A Massively Multiview System for Social Interaction
  Capture

abstract:
  We present an approach to capture the 3D motion of a group of people engaged
in a social interaction. The core challenges in capturing social interactions
are: (1) occlusion is functional and frequent; (2) subtle motion needs to be
measured over a space large enough to host a social group; (3) human appearance
and configuration variation is immense; and (4) attaching markers to the body
may prime the nature of interactions. The Panoptic Studio is a system organized
around the thesis that social interactions should be measured through the
integration of perceptual analyses over a large variety of view points. We
present a modularized system designed around this principle, consisting of
integrated structural, hardware, and software innovations. The system takes, as
input, 480 synchronized video streams of multiple people engaged in social
activities, and produces, as output, the labeled time-varying 3D structure of
anatomical landmarks on individuals in the space. Our algorithm is designed to
fuse the "weak" perceptual processes in the large number of views by
progressively generating skeletal proposals from low-level appearance cues, and
a framework for temporal refinement is also presented by associating body parts
to reconstructed dense 3D trajectory stream. Our system and method are the
first in reconstructing full body motion of more than five people engaged in
social interactions without using markers. We also empirically demonstrate the
impact of the number of views in achieving this goal.


title:
Characterization of Fully Depleted CMOS Active Pixel Sensors on High
  Resistivity Substrates for Use in a High Radiation Environment

abstract:
  Depleted CMOS active sensors (DMAPS) are being developed for high-energy
particle physics experiments in high radiation environments, such as in the
ATLAS High Luminosity Large Hadron Collider (HL-LHC). Since charge collection
by drift is mandatory for harsh radiation environment, the application of high
bias voltage to high resistive sensor material is needed. In this work, a
prototype of a DMAPS was fabricated in a 150nm CMOS process on a substrate with
a resistivity of >2 k{\Omega}cm that was thinned to 100 {\mu}m. Full depletion
occurs around 20V, which is far below the breakdown voltage of 110 V. A readout
chip has been attached for fast triggered readout. Presented prototype also
uses a concept of sub-pixel en/decoding three pixels of the prototype chip are
readout by one pixel of the readout chip. Since radiation tolerance is one of
the largest concerns in DMAPS, the CCPD_LF chip has been irradiated with X-rays
and neutrons up to a total ionization dose of 50 Mrad and a fluence of
10E15neq/cm2, respectively.


title:
On Higher Order Query Languages which on Relational Databases Collapse
  to Second Order Logic

abstract:
  In the framework of computable queries in Database Theory, there are many
examples of queries to (properties of) relational database instances that can
be expressed by simple and elegant third order logic ($\mathrm{TO}$) formulae.
In many of those properties the expressive power of $\mathrm{TO}$ is not
required, but the equivalent second order logic ($\mathrm{SO}$) formulae can be
very complicated or unintuitive. From the point of view of the study of highly
expressive query languages, it is then relevant to identify fragments of
$\mathrm{TO}$ (and, in general, of higher-order logics of order $\geq 3$) which
do have an $\mathrm{SO}$ equivalent formula. In this article we investigate
this precise problem as follows. Firstly, we define a general schema of
$\exists$TO formulas which consists of existentially quantifying a third-order
linear digraph of polynomial length, that is, a sequence of structures that
represents a computation, by explicitly stating which operations are the ones
which can be involved in the construction of a given structure in the sequence,
when applied to the previous one. Then we give a constructive proof of the fact
that all $\exists$TO sub formulas of that schema can be translated into an
equivalent SO formula. Secondly, aiming to formally characterize the fragment
of TO which can be translated to SO, we define a restriction of TO, which we
denote TO$^{P}$, for polynomial TO, and we give a constructive proof on the
fact that it collapses to SO. We define TO$^{P}$ as the fragment of TO where
valuations can assign to TO relation variables only TO relations whose
cardinalities are bounded by a polynomial that depends on the quantifier.
Moreover, we define a similar restriction for every higher order logic of order
$i \geq 4$, which we denote $\mathrm{HO}^{i,P}$, and give a constructive proof
of the fact that for all $i \geq 4$, $\mathrm{HO}^{i,P}$ collapses to SO.


title: Testing Bayesian Networks

abstract:
  This work initiates a systematic investigation of testing high-dimensional
structured distributions by focusing on testing Bayesian networks -- the
prototypical family of directed graphical models. A Bayesian network is defined
by a directed acyclic graph, where we associate a random variable with each
node. The value at any particular node is conditionally independent of all the
other non-descendant nodes once its parents are fixed. Specifically, we study
the properties of identity testing and closeness testing of Bayesian networks.
Our main contribution is the first non-trivial efficient testing algorithms for
these problems and corresponding information-theoretic lower bounds. For a wide
range of parameter settings, our testing algorithms have sample complexity
sublinear in the dimension and are sample-optimal, up to constant factors.

categories: cs.DS cs.IT cs.LG math.IT math.ST stat.TH


title: No fifth force in a scale invariant universe

abstract:
  We revisit the possibility that the Planck mass is spontaneously generated in
scale invariant scalar-tensor theories of gravity, typically leading to a
"dilaton." The fifth force, arising from the dilaton, is severely constrained
by astrophysical measurements. We explore the possibility that nature is
fundamentally Weyl-scale invariant and argue that, as a consequence, the fifth
force effects are dramatically suppressed and such models are viable. We
discuss possible obstructions to maintaining scale invariance and how these
might be resolved.


title: Remarks on Rindler Quantization

abstract:
  We review the quantization of scalar and gauge fields using Rindler
coordinates with an emphasis on the physics of the Rindler horizon. In the
thermal state at the Unruh temperature, correlators match their Minkowski
vacuum values and the renormalized stress tensor vanishes, while at any other
temperature the renormalized stress-energy diverges on the horizon. After
giving a new derivation of some of these results using canonical quantization
in the thermofield double state, we comment on the relevance of fluxes and
boundary conditions at the horizon, which have arisen in calculations of
entanglement entropy.


title: Spin-charge separation in an Aharonov-Bohm interferometer

abstract:
  We study manifestations of spin-charge separation (SCS) in transport through
a tunnel-coupled interacting single-channel quantum ring. We focus on the
high-temperature case (temperature $T$ larger than the level spacing $\Delta$)
and discuss both the classical (flux-independent) and interference
contributions to the tunneling conductance of the ring in the presence of
magnetic flux. We demonstrate that the SCS effects, which arise solely from the
electron-electron interaction, lead to the appearance of a peculiar fine
structure of the electron spectrum in the ring. Specifically, each level splits
into a series of sublevels, with their spacing governed by the interaction
strength. In the high-$T$ limit, the envelope of the series contains of the
order of $T/\Delta$ sublevels. At the same time, SCS suppresses the tunneling
width of the sublevels by a factor of $\Delta/T$. As a consequence, the
classical transmission through the ring remains unchanged compared to the
noninteracting case: the suppression of tunneling is compensated by the
increase of the number of tunneling channels. On the other hand, the
flux-dependent contribution to the conductance depends on the
interaction-induced dephasing rate which is known to be parametrically
increased by SCS in an infinite system. We show, however, that SCS is not
effective for dephasing in the limit of weak tunneling. Moreover, generically,
in the almost closed ring, the dephasing rate does not depend on the
interaction strength and is determined by the tunneling coupling to the leads.
In certain special symmetric cases, dephasing is further suppressed. Similar to
the spinless case, the high-$T$ conductance shows, as a function of magnetic
flux, a sequence of interaction-induced sharp negative peaks on top of the
classical contribution.


title: High Energy Neutrinos from the Tidal Disruption of Stars

abstract:
  We study the production of high energy neutrinos in jets from the tidal
disruption of stars by supermassive black holes. The diffuse neutrino flux
expected from these tidal disruption events (TDEs) is calculated both
analytically and numerically, taking account the dependence of the rate of TDEs
on the redshift and black hole mass. We find that ~10% of the observed diffuse
flux at IceCube at an energy of about 1 PeV can come from TDEs if the
characteristics of known jetted tidal disruption events are assumed to apply to
the whole population of these sources. If, however, plausible scalings of the
jet Lorentz factor or variability timescale with the black hole mass are taken
into account, the contribution of the lowest mass black holes to the neutrino
flux is enhanced. In this case, TDEs can account for most of the neutrino flux
detected at IceCube, describing both the neutrino flux normalization and
spectral shape with moderate baryonic loadings. While the uncertainties on our
assumptions are large, a possible signature of TDEs as the origin of the
IceCube signal is the transition of the flux flavor composition from a pion
beam to a muon damped source at the highest energies, which will also result in
a suppression of Glashow resonance events.


title:
Prophet Inequalities Made Easy: Stochastic Optimization by Pricing
  Non-Stochastic Inputs

abstract:
  We present a general framework for stochastic online maximization problems
with combinatorial feasibility constraints. The framework establishes prophet
inequalities by constructing price-based online approximation algorithms, a
natural extension of threshold algorithms for settings beyond binary selection.
Our analysis takes the form of an extension theorem: we derive sufficient
conditions on prices when all weights are known in advance, then prove that the
resulting approximation guarantees extend directly to stochastic settings. Our
framework unifies and simplifies much of the existing literature on prophet
inequalities and posted price mechanisms, and is used to derive new and
improved results for combinatorial markets (with and without complements),
multi-dimensional matroids, and sparse packing problems. Finally, we highlight
a surprising connection between the smoothness framework for bounding the price
of anarchy of mechanisms and our framework, and show that many smooth
mechanisms can be recast as posted price mechanisms with comparable performance
guarantees.


title: Additive invariants of orbifolds

abstract:
  In this article, using the recent theory of noncommutative motives, we
compute the additive invariants of orbifolds (equipped with a sheaf of Azumaya
algebras) using solely "fixed-point data". As a consequence, we recover, in a
unified and conceptual way, the original results of Vistoli concerning
algebraic K-theory, of Baranovsky concerning cyclic homology, of the second
author with Polishchuk concerning Hochschild homology, and of Baranovsky-Petrov
and Caldararu-Arinkin (unpublished) concerning twisted Hochschild homology; in
the case of topological Hochschild homology and periodic topological cyclic
homology, the aforementioned computation is new in the literature. As an
application, we verify Grothendieck's standard conjectures of type C and D, as
well as Voevodsky's smash-nilpotence conjecture, in the case of
"low-dimensional" orbifolds. Finally, we establish a result of independent
interest concerning nilpotency in the Grothendieck ring of an orbifold.


title: Was 49b: An Overmassive AGN in a Merging Dwarf Galaxy?

abstract:
  We present a combined morphological and X-ray analysis of Was 49, an
isolated, dual AGN system notable for the presence of a dominant AGN Was 49b in
the disk of the primary galaxy Was 49a, at a projected radial distance of 8 kpc
from the nucleus. Using X-ray data from Chandra, NuSTAR, and Swift, we find
that this AGN has a bolometric luminosity of L_bol ~ 2 x 10^45 erg/s, with a
black hole mass of M_BH=1.3^{+2.9}_{-0.9} x 10^8 M_Sol. Despite its large mass,
our analysis of optical data from the Discovery Channel Telescope shows that
the supermassive black hole is hosted by a stellar counterpart with a mass of
only 5.6^{+4.9}_{-2.6} x 10^9 M_Sol, making the SMBH potentially larger than
expected from SMBH-galaxy scaling relations, and the stellar counterpart
exhibits a morphology that is consistent with dwarf elliptical galaxies. Our
analysis of the system in the r and K bands indicates that Was 49 is a minor
merger, with a mass ratio of Was 49a to Was 49b between 1:7 and 1:15. This is
in contrast with findings that the most luminous merger-triggered AGNs are
found in major mergers, and that minor mergers predominantly enhance AGN
activity in the primary galaxy.


title:
Square Hellinger Subadditivity for Bayesian Networks and its
  Applications to Identity Testing

abstract:
  We show that the square Hellinger distance between two Bayesian networks on
the same directed graph, $G$, is subadditive with respect to the neighborhoods
of $G$. Namely, if $P$ and $Q$ are the probability distributions defined by two
Bayesian networks on the same DAG, our inequality states that the square
Hellinger distance, $H^2(P,Q)$, between $P$ and $Q$ is upper bounded by the
sum, $\sum_v H^2(P_{\{v\} \cup \Pi_v}, Q_{\{v\} \cup \Pi_v})$, of the square
Hellinger distances between the marginals of $P$ and $Q$ on every node $v$ and
its parents $\Pi_v$ in the DAG. Importantly, our bound does not involve the
conditionals but the marginals of $P$ and $Q$. We derive a similar inequality
for more general Markov Random Fields.
  As an application of our inequality, we show that distinguishing whether two
Bayesian networks $P$ and $Q$ on the same (but potentially unknown) DAG satisfy
$P=Q$ vs $d_{\rm TV}(P,Q)>\epsilon$ can be performed from
$\tilde{O}(|\Sigma|^{3/4(d+1)} \cdot n/\epsilon^2)$ samples, where $d$ is the
maximum in-degree of the DAG and $\Sigma$ the domain of each variable of the
Bayesian networks. If $P$ and $Q$ are defined on potentially different and
potentially unknown trees, the sample complexity becomes
$\tilde{O}(|\Sigma|^{4.5} n/\epsilon^2)$, whose dependence on $n, \epsilon$ is
optimal up to logarithmic factors. Lastly, if $P$ and $Q$ are product
distributions over $\{0,1\}^n$ and $Q$ is known, the sample complexity becomes
$O(\sqrt{n}/\epsilon^2)$, which is optimal up to constant factors.

categories: cs.LG cs.IT math.IT math.PR math.ST stat.ML stat.TH


title:
The second catalog of flaring gamma-ray sources from the Fermi All-sky
  Variability Analysis

abstract:
  We present the second catalog of flaring gamma-ray sources (2FAV) detected
with the Fermi All-sky Variability Analysis (FAVA), a tool that blindly
searches for transients over the entire sky observed by the Large Area
Telescope (LAT) on board the \textit{Fermi} Gamma-ray Space Telescope. With
respect to the first FAVA catalog, this catalog benefits from a larger data
set, the latest LAT data release (Pass 8), as well as from an improved analysis
that includes likelihood techniques for a more precise localization of the
transients. Applying this analysis on the first 7.4 years of \textit{Fermi}
observations, and in two separate energy bands 0.1$-$0.8 GeV and 0.8$-$300 GeV,
a total of 4547 flares has been detected with a significance greater than
$6\sigma$ (before trials), on the time scale of one week. Through spatial
clustering of these flares, 518 variable gamma-ray sources are identified.
Likely counterparts, based on positional coincidence, have been found for 441
sources, mostly among the blazar class of active galactic nuclei. For 77 2FAV
sources, no likely gamma-ray counterpart has been found. For each source in the
catalog, we provide the time, location, and spectrum of each flaring episode.
Studying the spectra of the flares, we observe a harder-when-brighter behavior
for flares associated with blazars, with the exception of BL Lac flares
detected in the low-energy band. The photon indexes of the flares are never
significantly smaller than 1.5. For a leptonic model, and under the assumption
of isotropy, this limit suggests that the spectrum of the freshly accelerated
electrons is never harder than $p\sim$2.


title:
Discovery of ferromagnetism with large magnetic anisotropy in ZrMnP and
  HfMnP

abstract:
  ZrMnP and HfMnP single crystals are grown by a self-flux growth technique and
structural as well as temperature dependent magnetic and transport properties
are studied. Both compounds have an orthorhombic crystal structure. ZrMnP and
HfMnP are ferromagnetic with Curie temperatures around $370$~K and $320$~K
respectively. The spontaneous magnetizations of ZrMnP and HfMnP are determined
to be $1.9$~$\mu_\textrm{B}$/f.u. and $2.1$~$\mu_\textrm{B}$/f.u. respectively
at $50$~K. The magnetocaloric effect of ZrMnP in term of entropy change
($\Delta S$) is estimated to be $-6.7$ kJm$^{-3}$K$^{-1}$ around $369$~K. The
easy axis of magnetization is [100] for both compounds, with a small anisotropy
relative to the [010] axis. At $50$~K, the anisotropy field along the [001]
axis is $\sim4.6$~T for ZrMnP and $\sim10$~T for HfMnP. Such large magnetic
anisotropy is remarkable considering the absence of rare-earth elements in
these compounds. The first principle calculation correctly predicts the
magnetization and hard axis orientation for both compounds, and predicts the
experimental HfMnP anisotropy field within 25 percent. More importantly, our
calculations suggest that the large magnetic anisotropy comes primarily from
the Mn atoms suggesting that similarly large anisotropies may be found in other
3d transition metal compounds.


title:
Quantum properties of a parametric four-wave mixing in a Raman-type
  atomic system

abstract:
  We present a study of the quantum properties of two light fields used to
parametric four-wave mixing in a Raman-type atomic system. The system realizes
an effective Hamiltonian of beamsplitter type coupling between the light
fields, which allows to control squeezing and amplitude distribution of the
light fields, as well as realizing their entanglement. The scheme can be
feasibly applied to engineer the quantum properties of two single-mode light
fields in properly chosen input states.


title:
Mathematical modelling of the electric sense of fish: the role of
  multi-frequency measurements and movement

abstract:
  Understanding active electrolocation in weakly electric fish remains a
challenging issue. In this article we propose a mathematical formulation of
this problem, in terms of partial differential equations. This allows us to
detail two algorithms: one for localizing a target using the multi-frequency
aspect of the signal, and antoher one for identifying the shape of this target.
Shape recognition is designed in a machine learning point of view, and take
advantage of both the multi-frequency setup and the movement of the fish around
its prey. Numerical simulations are shown for the computation of the electric
field emitted and sensed by the fish; they are then used as an input for the
two algorithms.


title: The kappa-(A)dS quantum algebra in (3+1) dimensions

abstract:
  The quantum duality principle is used to obtain explicitly the Poisson
analogue of the kappa-(A)dS quantum algebra in (3+1) dimensions as the
corresponding Poisson-Lie structure on the dual solvable Lie group. The
construction is fully performed in a kinematical basis and deformed Casimir
functions are also explicitly obtained. The cosmological constant $\Lambda$ is
included as a Poisson-Lie group contraction parameter, and the limit
$\Lambda\to 0$ leads to the well-known kappa-Poincar\'e algebra in the
bicrossproduct basis. A twisted version with Drinfel'd double structure of this
kappa-(A)dS deformation is sketched.


title: Security of a single-state semi-quantum key distribution protocol

abstract:
  Semi-quantum key distribution protocols are allowed to set up a secure secret
key between two users. Compared with their full quantum counterparts, one of
the two users is restricted to perform some "classical" or "semi-quantum"
operations, which makes them easily realizable by using less quantum resource.
However, the semi-quantum key distribution protocols mainly rely on a two-way
quantum channel. The eavesdropper has two opportunities to intercept the
quantum states transmitted in the quantum communication stage. It may allow the
eavesdropper to get more information and make the security analysis more
complicated. In the past ten years, many semi-quantum key distribution
protocols have been proposed and proved to be robust. But there are few works
concerned about their unconditional security. It is doubted that how secure the
semi-quantum ones are and how much noise can they tolerate to establish a
secure secret key. In this paper, we prove the unconditional security of a
single-state semi-quantum key distribution protocol proposed by $Zou$ et al. in
[Phys. Rev. A. 79]. We present a complete proof from information theory aspect
by deriving a lower bound of the protocol's key rate in the asymptotic
scenario. Using this bound, we figure out an error threshold value such that
all error rates are less than this threshold value, the secure secret key can
be established between the legitimate users definitely. Otherwise, the users
should abort the protocol. we make an illustration of the protocol under the
circumstance of the reverse quantum channel is a depolarizing one with
parameter $q$. Additionally, we compare the error threshold value with some
full quantum protocols and several existing semi-quantum ones whose
unconditional security proofs have been provided recently.


title:
Galactic disc profiles and a universal angular momentum distribution
  from statistical physics

abstract:
  We show that the stellar surface-brightness profiles in disc
galaxies---observed to be approximately exponential---can be explained if
radial migration efficiently scrambles the individual stars' angular momenta
while conserving the circularity of the orbits and the total mass and angular
momentum. In this case the disc's distribution of specific angular momenta $j$
should be near a maximum-entropy state and therefore approximately exponential,
$dN\propto\exp(-j/\langle j\rangle)dj$. This distribution translates to a
surface-density profile that is generally not an exponential function of
radius: $\Sigma(R)\propto\exp[-R/R_e(R)]/(RR_e(R))(1+d\log v_c(R)/d\log R)$,
for a rotation curve $v_c(R)$ and $R_e(R)\equiv\langle j\rangle/v_c(R)$. We
show that such a profile matches the observed surface-brightness profiles of
disc-dominated galaxies as well as the empirical exponential profile. Disc
galaxies that exhibit population gradients cannot have fully reached a
maximum-entropy state but appear to be close enough that their
surface-brightness profiles are well-fit by this idealized model.


title:
Horizon instability of extremal Reissner-Nordstr\"om black holes to
  charged perturbations

abstract:
  We investigate the stability of highly charged Reissner-Nordstr\"om black
holes to charged scalar perturbations. We show that the near-horizon region
exhibits a transient instability which becomes the Aretakis instability in the
extremal limit. The rates we obtain match the enhanced rates for
nonaxisymmetric perturbations of the near-extremal and extremal Kerr solutions.
The agreement is shown to arise from a shared near-horizon symmetry of the two
scenarios.


title: NPTFit: A code package for Non-Poissonian Template Fitting

abstract:
  We present NPTFit, an open-source code package, written in python and cython,
for performing non-Poissonian template fits (NPTFs). The NPTF is a
recently-developed statistical procedure for characterizing the contribution of
unresolved point sources (PSs) to astrophysical data sets. The NPTF was first
applied to Fermi gamma-ray data to give evidence that the excess of ~GeV
gamma-rays observed in the inner regions of the Milky Way likely arises from a
population of sub-threshold point sources, and the NPTF has since found
additional applications studying sub-threshold extragalactic sources at high
Galactic latitudes. The NPTF generalizes traditional astrophysical template
fits to allow for the ability to search for populations of unresolved PSs that
may follow a given spatial distribution. NPTFit builds upon the framework of
the fluctuation analyses developed in X-ray astronomy, and thus likely has
applications beyond those demonstrated with gamma-ray data. The NPTFit package
utilizes novel computational methods to perform the NPTF efficiently. The code
is available at https://github.com/bsafdi/NPTFit and up-to-date and extensive
documentation may be found at http://nptfit.readthedocs.io

categories: astro-ph.HE astro-ph.CO astro-ph.IM hep-ph


title:
Atmospheric Compositions of Three Brown Dwarfs and Implications for
  their Formation Conditions

abstract:
  The formation mechanisms and chemical compositions of brown dwarfs likely
span a diverse range. If they are formed predominantly in isolation by
gravitational collapse like dwarf stars then their compositions might follow
those of dwarf stars, spanning a relatively narrow range in metallicities (~
-0.4 to +0.4 dex) and predominantly oxygen-rich (C/O <~ 0.7). On the other
hand, giant planets in the solar system are all super-solar in metallicity
([C/H] > 0.5~dex), which is thought to be a consequence of formation by
core-accretion in a circumstellar disk. In this study we determine the
atmospheric chemical compositions of three brown dwarfs and find them to be
neither characteristic of dwarf stars nor giant planets. We derive
high-precision atmospheric chemical abundances using high-S/N HST near-infrared
spectra of three mid T Dwarfs which, together with two previously studied
objects, display distinctly sub-solar metallicities and span C/O ratios of
0.4-1.0. These abundance patterns indicate either an old sub-stellar population
and a multitude of formation environments or objects formed in circumstellar
disks followed by ejection later. We show that for a simple synthetic model
population of brown dwarfs with the same spectral-type as our sample the
predicted age distribution is predominantly older than the Sun and, hence, more
metal poor, consistent with our derived abundances. The diverse C/O ratios we
find are indicative of either different chemical reservoirs in their formation
environments or different formation pathways. Our results open the possibility
that cool brown dwarfs may provide important probes of early galactic chemical
evolution and inhomogeneity.