title: Decentralised Norm Monitoring in Open Multi-Agent Systems

abstract:
  We consider the problem of detecting norm violations in open multi-agent
systems (MAS). We show how, using ideas from scrip systems, we can design
mechanisms where the agents comprising the MAS are incentivised to monitor the
actions of other agents for norm violations. The cost of providing the
incentives is not borne by the MAS and does not come from fines charged for
norm violations (fines may be impossible to levy in a system where agents are
free to leave and rejoin again under a different identity). Instead, monitoring
incentives come from (scrip) fees for accessing the services provided by the
MAS. In some cases, perfect monitoring (and hence enforcement) can be achieved:
no norms will be violated in equilibrium. In other cases, we show that, while
it is impossible to achieve perfect enforcement, we can get arbitrarily close;
we can make the probability of a norm violation in equilibrium arbitrarily
small. We show using simulations that our theoretical results hold for
multi-agent systems with as few as 1000 agents---the system rapidly converges
to the steady-state distribution of scrip tokens necessary to ensure monitoring
and then remains close to the steady state.


title: Reflection groups, reflection arrangements, and invariant real varieties

abstract:
  Let $X$ be a nonempty real variety that is invariant under the action of a
reflection group $G$. We conjecture that if $X$ is defined in terms of the
first $k$ basic invariants of $G$ (ordered by degree), then $X$ meets a
$k$-dimensional flat of the associated reflection arrangement. We prove this
conjecture for the infinite types, reflection groups of rank at most $3$, and
$F_4$ and we give computational evidence for $H_4$. This is a generalization of
Timofte's degree principle to reflection groups. For general reflection groups,
we compute nontrivial upper bounds on the minimal dimension of flats of the
reflection arrangement meeting $X$ from the combinatorics of parabolic
subgroups. We also give generalizations to real varieties invariant under Lie
groups.


title:
The atmospheric circulation of a nine-hot Jupiter sample: Probing
  circulation and chemistry over a wide phase space

abstract:
  We present results from an atmospheric circulation study of nine hot Jupiters
that comprise a large transmission spectral survey using the Hubble and Spitzer
Space Telescopes. These observations exhibit a range of spectral behavior over
optical and infrared wavelengths which suggest diverse cloud and haze
properties in their atmospheres. By utilizing the specific system parameters
for each planet, we naturally probe a wide phase space in planet radius,
gravity, orbital period, and equilibrium temperature. First, we show that our
model "grid" recovers trends shown in traditional parametric studies of hot
Jupiters, particularly equatorial superrotation and increased day-night
temperature contrast with increasing equilibrium temperature. We show how
spatial temperature variations, particularly between the dayside and nightside
and west and east terminators, can vary by hundreds of K, which could imply
large variations in Na, K, CO and CH4 abundances in those regions. These
chemical variations can be large enough to be observed in transmission with
high-resolution spectrographs, such as ESPRESSO on VLT, METIS on the E-ELT, or
with MIRI and NIRSpec aboard JWST. We also compare theoretical emission spectra
generated from our models to available Spitzer eclipse depths for each planet,
and find that the outputs from our solar-metallicity, cloud-free models
generally provide a good match to many of the datasets, even without additional
model tuning. Although these models are cloud-free, we can use their results to
understand the chemistry and dynamics that drive cloud formation in their
atmospheres.


title:
Non-existence of Funk functions for Finsler spaces of non-vanishing
  scalar flag curvature

abstract:
  In his book "Differential Geometry of Spray and Finsler spaces", page 177,
Zhongmin Shen asks "wether or not there always exist non-trivial Funk functions
on a spray space". In this note, we will prove that the answer is negative for
the geodesic spray of a finslerian function of non-vanishing scalar flag
curvature.


title: On commutative $p$-schemes of order $p^4$

abstract:
  In this article, we consider the existence and schurity problem on
commutative $p$-schemes of order $p^4$. Using the thin radical and thin
residue, we give sufficient conditions for such $p$-schemes to be schurian. We
also give questions related to our results.


title:
Power operations in the Kunneth spectral sequence and commutative
  HFp-algebras

abstract:
  In this paper, we prove the multiplicativity of the K\"unneth spectral
sequence. This is established by an analogue of the Comparison Theorem from
homological algebra, which we suspect may be useful for other spectral
sequences. This multiplicativity is then used to compute the action of the
Dyer-Lashof algebra on $\HF_p \wedge_{ku} \HF_p$, $\HF_p \wedge_{\BP} \HF_p$,
and part of the action on $\HF_p \wedge_{MU} \HF_p$. We then relate these
computations to the construction of commutative $R$-algebra structures on
commutative $\HF_p$-algebras. In the case of $MU$, we obtain a necessary
closure condition on ideals $I\subset MU_*$ such that $MU/I$ can be realized as
a commutative $MU$-algebra.


title: On the Role of Collective Sensing and Evolution in Group Formation

abstract:
  Collective sensing is an emergent phenomenon which enables individuals to
estimate a hidden property of the environment through the observation of social
interactions. Previous work on collective sensing shows that gregarious
individuals obtain an evolutionary advantage by exploiting collective sensing
when competing against solitary individuals. This work addresses the question
of whether collective sensing allows for the emergence of groups from a
population of individuals without predetermined behaviors. It is assumed that
group membership does not lessen competition on the limited resources in the
environment, e.g. groups do not improve foraging efficiency. Experiments are
run in an agent-based evolutionary model of a foraging task, where the fitness
of the agents depends on their foraging strategy. The foraging strategy of
agents is determined by a neural network, which does not require explicit
modeling of the environment and of the interactions between agents. Experiments
demonstrate that gregarious behavior is not the evolutionary-fittest strategy
if resources are abundant, thus invalidating previous findings in a specific
region of the parameter space. In other words, resource scarcity makes
gregarious behavior so valuable as to make up for the increased competition
over the few available resources. Furthermore, it is shown that a population of
solitary agents can evolve gregarious behavior in response to a sudden scarcity
of resources, thus individuating a possible mechanism that leads to gregarious
behavior in nature. The evolutionary process operates on the whole parameter
space of the neural networks, hence these behaviors are selected among an
unconstrained set of behavioral models.


title: Approximation of linear functionals on the space with convex measure

abstract:
  There are two definitions of the measurable functional on the topological
vector space: as a linear and measurable real-valued function and as a
pointwise limit of the sequence of the continious linear functionals. In
general case they are not equivalent, but in some cases it is so, for example,
in the case of gaussian measures. There is one natural generalization of the
gaussian measures - the convex measures. In this paper this equivalence was
proved for the some classes of convex measures.


title:
A quality check of the $AKARI$ mid-infrared all-sky diffuse map toward
  the massive star-forming regions NGC 6334 and NGC 6357

abstract:
  We present a comparative study of CO and polycyclic aromatic hydrocarbon
(PAH) emission toward a region including the massive star-forming regions of
NGC 6334 and NGC 6357. We use the NANTEN $^{12}$CO($J$ = 1--0) data and the
$AKARI$ 9 $\mu$m All-Sky diffuse map in order to evaluate the calibration
accuracy of the $AKARI$ data. We confirm that the overall CO distribution shows
a good spatial correspondence with the PAH emission, and their intensities
exhibit a good power-law correlation with a spatial resolution down to 4$'$
over the region of 10$^\circ$$\times$10$^\circ$. We also reveal poorer
correlation for small scale structures between the two quantities toward NGC
6357, due to strong UV radiation from local sources. Larger scatter in the
correlation toward NGC 6357 indicates higher ionization degree and/or PAH
excitation than that of NGC 6334.


title:
Low mass Drell-Yan production of lepton pairs at forward directions at
  the LHC: a hybrid approach

abstract:
  We discuss Drell-Yan production of dileptons at high energies in forward
rapidity region in a hybrid high-energy approach. This approach uses
unintegrated gluon distributions in one proton and collinear quark/antiquark
distributions in the second proton. Corresponding momentum-space formula for
the differential cross sections in high-energy approximation has been derived
and will be presented. The relation to the commonly used dipole approach is
discussed. We conclude and illustrate that some results of the dipole
approaches are too approximate, as far as kinematics is considered, and in fact
cannot be used when comparing with real experimental data. We find that the
dipole formula is valid only in very forward/backward rapidity regions ($|y| >$
5) that cannot be studied experimentally in the moment. We performed
calculations of some differential cross sections for low-mass dilepton
production by the LHCb and ATLAS collaborations. In distinction to most of
dipole approaches, we include all of the four Drell-Yan structure functions,
although the impact of interference structure functions is rather small for the
relevant experimental cuts. We find that both side contributions ($g + q/\bar
q$ and $q/\bar q + g$) have to be included even for the LHCb rapidity coverage
which is in contradiction with what is usually done in the dipole approach. We
present results for different unintegrated gluon distributions from the
literature (some of them include saturation effects). We see no clear hints of
saturation even at small $M_{ll}$ when comparing with the LHCb data.


title: Optimal constants in normed planes

abstract:
  We define new geometric constants for normed planes, determine their optimal
values, and characterize types of planes for which these optimal values are
attained. Relations of these constants to several topics, such as areas and
distances from points to sides of triangles, are also investigated. We perform
some calculations of new and old constants given by trigonometric functions for
certain classes of norms, and a conjecture on vectors which are isosceles
orthogonal is disproved.


title: Field-Temperature Phase Diagram and Entropy Landscape of CeAuSb$_2$

abstract:
  We report a field-temperature phase diagram and an entropy map for the heavy
fermion compound CeAuSb$_2$. CeAuSb$_2$ orders antiferromagnetically below
$T_N=6.6$~K, and has two metamagnetic transitions, at 2.8 and 5.6~T. The
locations of the critical endpoints of the metamagnetic transitions, which may
play a strong role in the putative quantum criticality of CeAuSb$_2$ and
related compounds, are identified. The entropy map reveals an apparent entropy
balance with Fermi liquid behavior, implying that above the N\'{e}el transition
the Ce moments are incorporated into the Fermi liquid. High-field data showing
that the magnetic behavior is remarkably anisotropic are also reported.


title: Cosmological test with the QSO Hubble diagram

abstract:
  A Hubble diagram (HD) has recently been constructed in the redshift range
0<z<6.5 using a non-linear relation between the ultraviolet and X-ray
luminosities of QSOs. The Type Ia SN HD has already provided a high-precision
test of cosmological models, but the fact that the QSO distribution extends
well beyond the supernova range (z<1.8), in principle provides us with an
important complementary diagnostic whose significantly greater leverage in z
can impose tighter constraints on the distance versus redshift relationship. In
this paper, we therefore perform an independent test of nine different
cosmological models, among which six are expanding, while three are static.
Many of these are disfavoured by other kinds of observations (including the
aforementioned Type Ia SNe). We wish to examine whether the QSO HD confirms or
rejects these earlier conclusions. We find that four of these models
(Einstein-de Sitter, the Milne universe, the Static Universe with simple tired
light and the Static universe with plasma tired light) are excluded at the >99%
C.L. The Quasi-Steady State Model is excluded at >95% C.L. The remaining four
models (Lambda-CDM/wCDM, the R_h=ct Universe, the Friedmann open universe and a
Static universe with a linear Hubble law) all pass the test. However, only
Lambda-CDM/wCDM and $R_{\rm h}=ct$ also pass the Alcock-Paczynski (AP) test.
The optimized parameters in Lambda-CDM/wCDM are Omega_m=0.20^{+0.24}_{-0.20}
and w_{de}=-1.2^{+1.6}_{-infinity} (the dark-energy equation-of-state).
Combined with the AP test, these values become Omega_m=0.38^{+0.20}_{-0.19} and
w_{de}=-0.28^{+0.52}_{-0.40}. But whereas this optimization of parameters in
Lambda-CDM/wCDM creates some tension with their concordance values, the $R_{\rm
h}=ct$ Universe has the advantage of fitting the QSO and AP data without any
free parameters.


title:
Classification of the relative positions between a hyperboloid and a
  sphere

abstract:
  We characterize all possible relative positions between a hyperboloid of one
sheet and a sphere through the roots of a characteristic polynomial associated
to these quadrics. The classification is also suitable for a hyperboloid and a
ellipsoid in some situations.
  As an application, this provides a method to detect contact between the two
surfaces by a simple calculation in many real world applications.


title: Shielding electrostatic fields in polar semiconductor nanostructures

abstract:
  Modern opto-electronic devices are based on semiconductor heterostructures
employing the process of electron-hole pair annihilation. In particular polar
materials enable a variety of classic and even quantum light sources, whose
on-going optimisation endeavours challenge generations of researchers. However,
the key challenge - the inherent electric crystal polarisation of such
materials - remains unsolved and deteriorates the electron-hole pair
annihilation rate. Here, our approach introduces a sequence of reverse
interfaces to compensate these polarisation effects, while the polar, natural
crystal growth direction is maintained provoking a boost in device performance.
Former research approaches like growth on less-polar crystal planes or even the
stabilization of unnatural phases never reached industrial maturity. In
contrast, our solution allows the adaptation of all established industrial
processes, while the polarisation becomes adjustable; even across zero. Hence,
our approach marks the onset of an entire class of ultra-fast and efficient
devices based on any polar material.


title: Convexification of Learning from Constraints

abstract:
  Regularized empirical risk minimization with constrained labels (in contrast
to fixed labels) is a remarkably general abstraction of learning. For common
loss and regularization functions, this optimization problem assumes the form
of a mixed integer program (MIP) whose objective function is non-convex. In
this form, the problem is resistant to standard optimization techniques. We
construct MIPs with the same solutions whose objective functions are convex.
Specifically, we characterize the tightest convex extension of the objective
function, given by the Legendre-Fenchel biconjugate. Computing values of this
tightest convex extension is NP-hard. However, by applying our characterization
to every function in an additive decomposition of the objective function, we
obtain a class of looser convex extensions that can be computed efficiently.
For some decompositions, common loss and regularization functions, we derive a
closed form.


title: Verification of BOUT++ by the Method of Manufactured Solutions

abstract:
  BOUT++ is a software package designed for solving plasma fluid models. It has
been used to simulate a wide range of plasma phenomena ranging from linear
stability analysis to 3D plasma turbulence, and is capable of simulating a wide
range of drift-reduced plasma fluid and gyro-fluid models. A verification
exercise has been performed as part of a EUROfusion Enabling Research project,
to rigorously test the correctness of the algorithms implemented in BOUT++, by
testing order-of-accuracy convergence rates using the Method of Manufactured
Solutions (MMS). We present tests of individual components including
time-integration and advection schemes, non-orthogonal coordinate systems and
the shifted metric procedure which is used to handle highly sheared grids. The
Flux Coordinate Independent (FCI) approach to differencing along magnetic
field-lines has been implemented in BOUT++, and is here verified using the MMS
in a sheared slab configuration. Finally we show tests of three complete
models: 2-field Hasegawa-Wakatani, 3-field reduced MHD in 3D toroidal
coordinates, and 5-field reduced MHD in slab geometry.


title:
Long-term analysis of semilinear wave equations with slowly varying wave
  speed

abstract:
  A semilinear wave equation with slowly varying wave speed is considered in
one to three space dimensions on a bounded interval, a rectangle or a box,
respectively. It is shown that the action, which is the harmonic energy divided
by the wave speed and multiplied with the diameter of the spatial domain, is an
adiabatic invariant: it remains nearly conserved over long times, longer than
any fixed power of the time scale of changes in the wave speed in the case of
one space dimension, and longer than can be attained by standard perturbation
arguments in the two- and three-dimensional cases. The long-time
near-conservation of the action yields long-time existence of the solution. The
proofs use modulated Fourier expansions in time.


title: Multiple perturbations of a singular eigenvalue problem

abstract:
  We study the perturbation by a critical term and a $(p-1)$-superlinear
subcritical nonlinearity of a quasilinear elliptic equation containing a
singular potential. By means of variational arguments and a version of the
concentration-compactness principle in the singular case, we prove the
existence of solutions for positive values of the parameter under the principal
eigenvalue of the associated singular eigenvalue problem.


title:
Features of non-congruent phase transition in modified Coulomb model of
  the binary ionic mixture

abstract:
  Non-congruent gas-liquid phase transition (NCPT) have been studied in
modified Coulomb model of a binary ionic mixture C(+6) + O(+8) on a
\textit{uniformly compressible} ideal electronic background /BIM($\sim$)/. The
features of NCPT in improved version of the BIM($\sim$) model for the same
mixture on background of \textit{non-ideal} electronic Fermi-gas and comparison
it with the previous calculations are the subject of present study. Analytical
fits for Coulomb corrections to EoS of electronic and ionic subsystems were
used in present calculations within the Gibbs--Guggenheim conditions of
non-congruent phase equilibrium.Parameters of critical point-line (CPL) were
calculated on the entire range of proportions of mixed ions $0<X<1$. Strong
"distillation" effect was found for NCPT in present BIM($\sim$) model. Just
similar distillation was obtained in variant of NCPT in dense nuslear matter.
The absence of azeotropic compositions was revealed in studied variants of
BIM($\sim$) in contrast to explicit existence of azeotropic compositions for
the NCPT in chemically reacting plasmas and in astrophysical applications.


title: Simple t-designs: A recursive construction for arbitrary t

abstract:
  The aim of this paper is to present a recursive construction of simple
t-designs for arbitrary t. The construction is of purely combinatorial nature
and it requires finding solutions for the indices of the ingredient designs
that satisfy a certain set of equalities. We give a small number of examples to
illustrate the construction, whereby we have found a large number of new
t-designs, which were previously unknown. This indicates that the method is
useful and powerful.


title: Extreme points in non-positive curvature

abstract:
  A natural analogue of the Krein--Milman theorem is shown to fail for CAT(0)
spaces.


title: $\Gamma$-structures and symmetric spaces

abstract:
  $\Gamma$-structures are weak forms of multiplications on closed oriented
manifolds. As shown by Hopf the rational cohomology algebras of manifolds
admitting $\Gamma$-structures are free over odd degree generators. We prove
that this condition is also sufficient for the existence of $\Gamma$-structures
on manifolds which are nilpotent in the sense of homotopy theory. This includes
homogeneous spaces with connected isotropy groups.
  Passing to a more geometric perspective we show that on compact oriented
Riemannian symmetric spaces with connected isotropy groups and free rational
cohomology algebras the canonical products given by geodesic symmetries define
$\Gamma$-structures. This extends work of Albers, Frauenfelder and Solomon on
$\Gamma$-structures on Lagrangian Grassmannians.


title:
Study of $\psi$ decays to the $\Xi^{-}\bar\Xi^{+}$ and
  $\Sigma(1385)^{\mp}\bar\Sigma(1385)^{\pm}$ final states

abstract:
  We study the decays of the charmonium resonances $J/\psi$ and $\psi(3686)$ to
the final states $\Xi^{-}\bar\Xi^{+}$,
$\Sigma(1385)^{\mp}\bar\Sigma(1385)^{\pm}$ based on a single baryon tag method
using data samples of $(223.7 \pm 1.4) \times 10^{6}$ $J/\psi$ and $(106.4 \pm
0.9) \times 10^{6}$ $\psi(3686)$ events collected with the BESIII detector at
the BEPCII collider. The decay
$\psi(3686)\rightarrow\Sigma(1385)^{\mp}\bar\Sigma(1385)^{\pm}$ is observed for
the first time, and the measurements of the other processes, including the
branching fractions and angular distributions, are in good agreement with and
much more precise than the previously published results. Additionally, the
ratios
$\frac{{\cal{B}}(\psi(3686)\rightarrow\Xi^{-}\bar\Xi^{+})}{{\cal{B}}(J/\psi\rightarrow\Xi^{-}\bar\Xi^{+})}$,
$\frac{{\cal{B}}(\psi(3686)\rightarrow\Sigma(1385)^{-}\bar\Sigma(1385)^{+})}{{\cal{B}}(J/\psi\rightarrow\Sigma(1385)^{-}\bar\Sigma(1385)^{+})}$
and
$\frac{{\cal{B}}(\psi(3686)\rightarrow\Sigma(1385)^{+}\bar\Sigma(1385)^{-})}{{\cal{B}}(J/\psi\rightarrow\Sigma(1385)^{+}\bar\Sigma(1385)^{-})}$
are determined.


title: Intrinsic structure of minimal discs in metric spaces

abstract:
  We study the intrinsic structure of parametric minimal discs in metric spaces
admitting a quadratic isoperimetric inequality. We associate to each minimal
disc a compact, geodesic metric space whose geometric, topological, and
analytic properties are controlled by the isoperimetric inequality. Its
geometry can be used to control the shapes of all curves and therefore the
geometry and topology of the original metric space. The class of spaces arising
in this way as intrinsic minimal discs is a natural generalization of the class
of Ahlfors regular discs, well-studied in analysis on metric spaces.


title:
Holographic entanglement entropy for hollow cones and banana shaped
  regions

abstract:
  We consider banana shaped regions as examples of compact regions, whose
boundary has two conical singularities. Their regularised holographic entropy
is calculated with all divergent as well as finite terms. The coefficient of
the squared logarithmic divergence, also in such a case with internally curved
boundary, agrees with that calculated in the literature for infinite circular
cones with their internally flat boundary. For the otherwise conformally
invariant coefficient of the ordinary logarithmic divergence an anomaly under
exceptional conformal transformations is observed.
  The construction of minimal submanifolds, needed for the entanglement entropy
of cones, requires fine-tuning of Cauchy data. Perturbations of such
fine-tuning leads to solutions relevant for hollow cones. The divergent parts
for the entanglement entropy of hollow cones are calculated. Increasing the
difference between the opening angles of their outer and inner boundary, one
finds a transition between connected solutions for small differences to
disconnected solutions for larger ones.


title: Status and Perspectives of the Search for Eta-Mesic Nuclei

abstract:
  In this report the search for eta-mesic nuclei is reviewed. The brief
description of the experimental studies is presented with a focus on the
possible production of the eta-nucleus bound states for light nuclei like 4He
and 3He.


title:
The decay of quadrupole-octupole $1^-$ states in $^{40}$Ca and
  $^{140}$Ce

abstract:
  Background: Two-phonon excitations originating from the coupling of two
collective one-phonon states are of great interest in nuclear structure
physics. One possibility to generate low-lying $E1$ excitations is the coupling
of quadrupole and octupole phonons.
  Purpose: In this work, the $\gamma$-decay behavior of candidates for the
$(2_1^+\otimes 3_1^-)_{1^-}$ state in the doubly-magic nucleus $^{40}$Ca and in
the heavier and semi-magic nucleus $^{140}$Ce is investigated.
  Methods: $(\vec{\gamma},\gamma')$ experiments have been carried out at the
High Intensity $\gamma$-ray Source (HI${\gamma}$S) facility in combination with
the high-efficiency $\gamma$-ray spectroscopy setup $\gamma^3$ consisting of
HPGe and LaBr$_3$ detectors. The setup enables the acquisition of
$\gamma$-$\gamma$ coincidence data and, hence, the detection of direct decay
paths.
  Results: In addition to the known ground-state decays, for $^{40}$Ca the
decay into the $3^-_1$ state was observed, while for $^{140}$Ce the direct
decays into the $2^+_1$ and the $0^+_2$ state were detected. The experimentally
deduced transition strengths and excitation energies are compared to
theoretical calculations in the framework of EDF theory plus QPM approach and
systematically analyzed for $N=82$ isotones. In addition, negative parities for
two $J=1$ states in $^{44}$Ca were deduced simultaneously.
  Conclusions: The experimental findings together with the theoretical
calculations support the two-phonon character of the $1^-_1$ excitation in the
light-to-medium-mass nucleus $^{40}$Ca as well as in the stable even-even
$N=82$ nuclei.


title:
Three-dimensional simulations of rapidly rotating core-collapse
  supernovae: finding a neutrino-powered explosion aided by non-axisymmetric
  flows

abstract:
  We report results from a series of three-dimensional (3D) rotational
core-collapse simulations for $11.2$ and 27 $M_{/odot}$ stars employing
neutrino transport scheme by the isotropic diffusion source approximation. By
changing the initial strength of rotation systematically, we find a
rotation-assisted explosion for the 27$M_{/odot}$ progenitor, which fails in
the absence of rotation. The unique feature was not captured in previous
two-dimensional (2D) self-consistent rotating models because the growing
non-axisymmetric instabilities play a key role. In the rapidly rotating case,
strong spiral flows generated by the so-called low $T/|W|$ instability enhance
the energy transport from the proto-neutron star (PNS) to the gain region,
which makes the shock expansion more energetic. The explosion occurs more
strongly in the direction perpendicular to the rotational axis, which is
different from previous 2D predictions.


title: Size and Stanley depth of monomial ideals

abstract:
  The Lyubeznik size of a monomial ideal $I$ of a polynomial ring $S$ is a
lower bound for the Stanley depth of $I$ decreased by $1$. A proof given by
Herzog-Popescu-Vladoiu had a gap which is solved here.


title:
Excited hadrons and the analytical structure of bound-state interaction
  kernels

abstract:
  We highlight Hermiticity issues in bound-state equations whose kernels are
subject to a highly asymmetric mass and momentum distribution and whose
eigenvalue spectrum becomes complex for radially excited states. We trace back
the presence of imaginary components in the eigenvalues and wave functions to
truncation artifacts and suggest how they can be eliminated in the case of
charmed mesons. The solutions of the gap equation in the complex plane, which
play a crucial role in the analytic structure of the Bethe-Salpeter kernel, are
discussed for several interaction models and qualitatively and quantitatively
compared to analytic continuations by means of complex-conjugate pole models
fitted to real solutions.


title:
Time and Energy Measurement Electronics for Silicon Drift Detector Aimed
  for X-ray Pulsar Navigation

abstract:
  A readout electronic with high time and energy resolution performance is
designed for the SDD (Silicon Drift Detector) signals readout, which is aimed
for X-ray pulsar based navigation (XNAV). For time measurement, the input
signal is fed into a fast shaping and Constant Fraction Discrimination (CFD)
circuit, and then be digitalized by a Time-to-Digital Converter (TDC)
implemented in an Field Programmable Gate Array (FPGA), which is designed with
a bin size of 2.5 ns. For energy measurement, a slow shaping and analog peak
detection circuit is employed to acquire the energy information of input
signals, which is then digitalized by a 14-bit Analog-to-Digital Converter
(ADC). Both the time and energy measurement results are buffered and packaged
in FPGA and then transmitted to Data Processing (DP) system. Test results
indicate that the time resolution is about 3 ns, while the FWHM (Full Width at
Half Maximum) of energy spectrum is better than 160 eV @ 5.9 keV, with the
energy dynamic range from 1 keV to 10 keV. Meanwhile, the linearity test shows
that the residual is less than 1.5% with different coming photons.


title:
Algorithm 979: Recursive Algorithms for Dense Linear Algebra -- The
  ReLAPACK Collection

abstract:
  To exploit both memory locality and the full performance potential of highly
tuned kernels, dense linear algebra libraries such as LAPACK commonly implement
operations as blocked algorithms. However, to achieve next-to-optimal
performance with such algorithms, significant tuning is required. On the other
hand, recursive algorithms are virtually tuning free, and yet attain similar
performance. In this paper, we first analyze and compare blocked and recursive
algorithms in terms of performance, and then introduce ReLAPACK, an open-source
library of recursive algorithms to seamlessly replace most of LAPACK's blocked
algorithms. In many scenarios, ReLAPACK clearly outperforms reference LAPACK,
and even improves upon the performance of optimizes libraries.


title:
On the GeV excess in the diffuse \gamma-ray emission towards the
  Galactic Center

abstract:
  The Fermi-LAT \gamma-ray data have been used to study the morphological and
spectral features of the so-called GeV excess - a diffuse radiation component
recently discovered towards the Galactic centre. We used the likelihood method
to analyze Fermi-LAT data. Our study does confirm the existence of such an
extra component in the diffuse \gamma-ray emission at GeV energies. Based on a
detailed morphological analysis, a spatial template that fits the data best was
generated and adopted. Using this template, the energy distribution of
\gamma-rays was derived in the 0.3-30 GeV energy interval. The spectrum
appeared to have less distinct ('bump'-like) structure than previous reported.
We argue that the morphology of this radiation component has a bipolar rather
than a spherically symmetric structure as has been assumed a priori in previous
studies. This finding excludes the associations of the GeV excess with Dark
Matter. We briefly discuss the radiation mechanisms and possible source
populations that could be responsible for this new component of diffuse gamma
radiation.


title: On an Optimal Extraction Problem with Regime Switching

abstract:
  This paper studies a finite-fuel two-dimensional degenerate singular
stochastic control problem under regime switching that is motivated by the
optimal irreversible extraction problem of an exhaustible commodity. A company
extracts a natural resource from a reserve with finite capacity, and sells it
in the market at a spot price that evolves according to a Brownian motion with
volatility modulated by a two-state Markov chain. In this setting, the company
aims at finding the extraction rule that maximizes its expected discounted cash
flow, net of the costs of extraction and maintenance of the reserve. We provide
expressions both for the value function and for the optimal control. On the one
hand, if the running cost for the maintenance of the reserve is a convex
function of the reserve level, the optimal extraction rule prescribes a
Skorokhod reflection of the (optimally) controlled state process at a certain
state and price dependent threshold. On the other hand, in presence of a
concave running cost function it is optimal to instantaneously deplete the
reserve at the time at which the commodity's price exceeds an endogenously
determined critical level. In both cases, the threshold triggering the optimal
control is given in terms of the optimal stopping boundary of an auxiliary
family of perpetual optimal selling problems with regime switching.


title:
Staggering antiferromagnetic domain wall velocity in a staggered
  spin-orbit field

abstract:
  We demonstrate the possibility to drive an antiferromagnet domain-wall at
high velocities by field-like N\'{e}el spin-orbit torques. Such torques arise
from current-induced local fields that alternate their orientation on each
sub-lattice of the antiferromagnet and whose orientation depend primarily on
the current direction, giving them their field-like character. The domain-wall
velocities that can be achieved by this mechanism are two orders of magnitude
greater than the ones in ferromagnets. This arises from the efficiency of the
staggered spin-orbit fields to couple to the order parameter and from the
exchange-enhanced phenomena in antiferromagnetic texture dynamics, which leads
to a low domain-wall effective mass and the absence of a Walker break-down
limit. In addition, because of its nature, the staggered spin-orbit field can
lift the degeneracy between two 180$^\circ$ rotated states in a collinear
antiferromagnet and provides a force that can move such walls and control the
switching of the states.


title:
On the universal $\mathrm{CH}_0$ group of cubic threefolds in positive
  characteristic

abstract:
  We adapt for algebraically closed fields $k$ of characteristic greater than
$2$ two results of Voisin, on the decomposition of the diagonal of a smooth
cubic hypersurface $X$ of dimension $3$ over $\mathbb C$, namely: the
equivalence between Chow-theoretic and cohomological decompositions of the
diagonal of those hypersurfaces and the fact that the algebraicity (with
$\mathbb Z_2$-coefficients) of the minimal class $\theta^4/4!$ of the
intermediate jacobian $J(X)$ of $X$ implies the Chow-theoretic decomposition of
the diagonal of $X$. Using the second result, the Tate conjecture for divisors
on surfaces defined over finite fields predicts, via a theorem of Schoen, that
every smooth cubic hypersurface of dimension $3$ over the algebraic closure of
a finite field of characteristic $>2$ admits a Chow-theoretic decomposition of
the diagonal.


title:
Specific heat in high magnetic fields and magnetic phase diagram of
  CePt$_2$In$_7$

abstract:
  We report specific heat measurements on a high quality single crystal of the
heavy-fermion compound CePt$_2$In$_7$ in magnetic fields up to 27 T. The
zero-field specific heat data above the N\'{e}el temperature, $T_N$, suggest a
moderately enhanced value of the electronic specific heat coefficient $\gamma =
180 \; \rm{mJ/K^2mol}$. For $T<T_N$, the data at zero applied magnetic field
are consistent with the existence of an anisotropic spin-density wave opening a
gap on almost entire Fermi surface, suggesting extreme two-dimensional
electronic and magnetic structures for CePt$_2$In$_7$. $T_N$ is monotonically
suppressed by magnetic field applied along the $c$-axis. When field is applied
parallel to the $a$-axis, $T_N$ first increases at low field up to about 10 T
and then decreases monotonically at higher field. Magnetic phase diagram based
on specific heat measurements suggests that a field-induced quantum critical
point is likely to occur slightly below 60 T for both principal orientations of
the magnetic field.


title:
Electromagnetic spectral properties and Debye screening of a strongly
  magnetized hot medium

abstract:
  We have evaluated the electromagnetic spectral function and its spectral
properties by computing the one-loop photon polarization tensor in presence of
magnetic field, particularly in a strong field approximation compared to the
thermal scale. When the magnetic scale is higher than the thermal scale the
lowest Landau level (LLL) becomes effectively (1+1) dimensional strongly
correlated system that provides a kinematical threshold based on the mass
scale. Beyond this threshold the photon strikes the LLL and the spectral
strength starts with a high value due to the dimensional reduction and then
falls off with increase of the photon energy due to LLL dynamics in a strong
field approximation. This strongly enhances the dilepton rate over the thermal
perturbative leading order (Born) rate at very low invariant mass. We have also
investigated the electromagnetic screening by computing the Debye screening
mass and it depends distinctively on three different scales (mass of the
quasiquark, temperature and the magnetic field strength) of a hot magnetized
system. The mass dependence of the Debye screening supports the occurrence of a
magnetic catalysis effect in the strong field approximation.


title: Temporal correlations of the running maximum of a Brownian trajectory

abstract:
  We study the correlations between the maxima $m$ and $M$ of a Brownian motion
(BM) on the time intervals $[0,t_1]$ and $[0,t_2]$, with $t_2>t_1$. We
determine exact forms of the distribution functions $P(m,M)$ and $P(G = M -
m)$, and calculate the moments $\mathbb{E}\{\left(M - m\right)^k\}$ and the
cross-moments $\mathbb{E}\{m^l M^k\}$ with arbitrary integers $l$ and $k$. We
show that correlations between $m$ and $M$ decay as $\sqrt{t_1/t_2}$ when
$t_2/t_1 \to \infty$, revealing strong memory effects in the statistics of the
BM maxima. We also compute the Pearson correlation coefficient $\rho(m,M)$, the
power spectrum of $M_t$, and we discuss a possibility of extracting the
ensemble-averaged diffusion coefficient in single-trajectory experiments using
a single realization of the maximum process.

categories: cond-mat.stat-mech math.PR math.ST stat.TH


title: Rewriting modulo symmetric monoidal structure

abstract:
  String diagrams are a powerful and intuitive graphical syntax for terms of
symmetric monoidal categories (SMCs). They find many applications in computer
science and are becoming increasingly relevant in other fields such as physics
and control theory.
  An important role in many such approaches is played by equational theories of
diagrams, typically oriented and applied as rewrite rules. This paper lays a
comprehensive foundation of this form of rewriting. We interpret diagrams
combinatorially as typed hypergraphs and establish the precise correspondence
between diagram rewriting modulo the laws of SMCs on the one hand and double
pushout (DPO) rewriting of hypergraphs, subject to a soundness condition called
convexity, on the other. This result rests on a more general characterisation
theorem in which we show that typed hypergraph DPO rewriting amounts to diagram
rewriting modulo the laws of SMCs with a chosen special Frobenius structure.
  We illustrate our approach with a proof of termination for the theory of
non-commutative bimonoids.


title:
A first theoretical realization of honeycomb topological magnon
  insulator

abstract:
  It has been recently shown that in the Heisenberg (anti)ferromagnet on the
honeycomb lattice, the magnons (spin wave quasipacticles) realize a massless
two-dimensional (2D) Dirac-like Hamiltonian. It was shown that the Dirac magnon
Hamiltonian preserves time-reversal symmetry defined with the sublattice pseudo
spins and the Dirac points are robust against magnon-magnon interactions. The
Dirac points also occur at nonzero energy. In this paper, we propose a simple
realization of nontrivial topology (magnon edge states) in this system. We show
that the Dirac points are gapped when the inversion symmetry of the lattice is
broken by introducing a next-nearest neighbour Dzyaloshinskii-Moriya (DM)
interaction. Thus, the system realizes magnon edge states similar to Haldane
model for quantum anomalous Hall effect in electronic systems. However, in
contrast to electronic spin current where dissipation can be very large due to
Ohmic heating, noninteracting topological magnons can propagate for long time
without dissipation as magnons are uncharged particles. We observe the same
magnon edge states for the XY model on the honeycomb lattice. Remarkably, in
this case the model maps to interacting hardcore bosons on the honeycomb
lattice. Quantum magnetic systems with nontrivial magnon edge states are called
topological magnon insulators. They have been studied theoretically on the
kagome lattice and recently observed experimentally on the kagome magnet
Cu(1-3, bdc) with three magnon bulk bands. Our results for the honeycomb
lattice suggests an experimental procedure to search for honeycomb topological
magnon insulators within a class of 2D quantum magnets and ultracold atoms
trapped in honeycomb optical lattices.


title: The Representation Theory of Dynkin Quivers. Three Contributions

abstract:
  These notes provide three contributions to the (well-established)
representation theory of Dynkin and Euclidean quivers. They should be helpful
as part of a direct approach to study representations of quivers, and they may
shed some new light on properties of Dynkin and Euclidean quivers.
  Part 1 deals with the case A (see arXiv:1304.5720). Part 2 concerns the case
D. We show that the category of representation of D_n contains a full
subcategory which is equivalent to the category of representations of a quiver
of type D_{n-1} such that the remaining indecomposable representations are
thin. This suggests an inductive procedure to deal with the D-cases, starting
with D_3 = A_3. Part 3 deals with the cases E. It provides a uniform way to
construct the maximal indecomposable representation for these Dynkin quivers as
well as a unified method to deal with the corresponding Euclidean quivers.
  The level of the presentation varies considerably and increases throughout
the discussion. Whereas Part 1 is completely elementary, just based on some
results in linear algebra, the further text is less self-contained and uses
one-point extensions, simplification, perpendicular categories,
Auslander-Reiten quivers and hammocks.


title: Iron Oxide Surfaces

abstract:
  The surface science of iron oxides is comprehensively reviewed. For the full
abstract please see pdf.


title: A stochastic model for non-relativistic particle acceleration

abstract:
  A stochastic model is proposed for the acceleration of non-relativistic
particles yielding to energy spectra with a shape of a Weibull\textquoteright s
function. Such particle distribution is found as the stationary solution of a
diffusion-loss equation in the framework of a second order Fermi\textquoteright
s mechanism producing anomalous diffusion for particle velocity. The present
model is supported by in situ observations of energetic particle enhancements
at interplanetary shocks, as here illustrated by means of an event seen by
STEREO B instruments in the heliosphere. Results indicate that the second order
Fermi\textquoteright s mechanism provides a viable explanation for the
acceleration of energetic particles at collisioness shock waves.


title: Lecture on Gauge Gravitation Theory. Gravity as a Higgs Field

abstract:
  Gravitation theory is formulated as gauge theory on natural bundles with
spontaneous symmetry breaking where gauge symmetries are general covariant
transformations, gauge fields are general linear connections, and Higgs fields
are pseudo-Riemannian metrics.


title:
Modification of the Nuclear Landscape in the Inverse Problem Framework
  using the Generalized Bethe-Weizs\"{a}cker Mass Formula

abstract:
  The dependence on the structure functions and Z, N numbers of the nuclear
binding energy is investigated within the inverse problem(IP) approach. This
approach allows us to infer the underlying model parameters from experimental
observation, rather than to predict the observations from the model parameters.
The IP was formulated for the numerical generalization of the semi-empirical
mass formula of BW. It was solved in step by step way based on the AME2012
nuclear database. The established parametrization describes the measured
nuclear masses of 2564 isotopes with a maximum deviation less than 2.6 MeV,
starting from the number of protons and number of neutrons equal to 1. The set
of parameters $\{a_{i}\}$, $i=1,\dots, {\mathcal{N}}_{\rm{param}}$ of our fit
represent the solution of an overdetermined system of nonlinear equations,
which represent equalities between the binding energy
$E_{B,j}^{\rm{Expt}}(A,Z)$ and its model $E_{B,j}^{\rm{Th}}(A,Z,\{a_{i}\})$,
where $j$ is the index of the given isotope. The solution of the overdetermined
system of nonlinear equations has been obtained with the help of the
Aleksandrov's auto-regularization method of Gauss-Newton(GN) type for ill-posed
problems. The efficiency of the above methods was checked by comparing relevant
results with the results obtained independently. The explicit form of unknown
functions was discovered in a step-by-step way using the modified least
$\chi^{2}$ procedure, that realized in the algorithms which were developed by
Aleksandrov to solve nonlinear systems of equations via the GN method, lets us
to choose between two functions with same $\chi^{2}$ the better one. In the
obtained generalized model the corrections to the binding energy depend on nine
proton (2, 8, 14, 20, 28, 50, 82, 108, 124) and ten neutron (2, 8, 14, 20, 28,
50, 82, 124, 152, 202) magic numbers as well on the asymptotic boundaries of
their influence.


title: Shortest path embeddings of graphs on surfaces

abstract:
  The classical theorem of F\'{a}ry states that every planar graph can be
represented by an embedding in which every edge is represented by a straight
line segment. We consider generalizations of F\'{a}ry's theorem to surfaces
equipped with Riemannian metrics. In this setting, we require that every edge
is drawn as a shortest path between its two endpoints and we call an embedding
with this property a shortest path embedding. The main question addressed in
this paper is whether given a closed surface S, there exists a Riemannian
metric for which every topologically embeddable graph admits a shortest path
embedding. This question is also motivated by various problems regarding
crossing numbers on surfaces.
  We observe that the round metrics on the sphere and the projective plane have
this property. We provide flat metrics on the torus and the Klein bottle which
also have this property.
  Then we show that for the unit square flat metric on the Klein bottle there
exists a graph without shortest path embeddings. We show, moreover, that for
large g, there exist graphs G embeddable into the orientable surface of genus
g, such that with large probability a random hyperbolic metric does not admit a
shortest path embedding of G, where the probability measure is proportional to
the Weil-Petersson volume on moduli space.
  Finally, we construct a hyperbolic metric on every orientable surface S of
genus g, such that every graph embeddable into S can be embedded so that every
edge is a concatenation of at most O(g) shortest paths.


title: Epimorphisms of 3-manifold groups

abstract:
  Let $f\colon M\to N$ be a proper map between two aspherical compact
orientable 3-manifolds with empty or toroidal boundary. We assume that $N$ is
not a closed graph-manifold. Suppose that $f$ induces an epimorphism on
fundamental groups. We show that $f$ is homotopic to a homeomorphism if one of
the following holds: either for any finite-index subgroup $\Gamma$ of
$\pi_1(N)$ the ranks of $\Gamma$ and of $f_*^{-1}(\Gamma)$ agree, or for any
finite cover $\tilde{N}$ of $N$ the Heegaard genus of $\tilde{N}$ and the
Heegaard genus of the pull-back cover $\tilde{M}$ agree.


title: Packing minor-closed families of graphs into complete graphs

abstract:
  Motivated by a conjecture of Gy\'arf\'as, recently B\"ottcher, Hladk\'y,
Piguet, and Taraz showed that every collection $T_1,\dots,T_t$ of trees on $n$
vertices with $\sum_{i=1}^te(T_i)\leq \binom{n}{2}$ and with bounded maximum
degree, can be packed into the complete graph on $(1+o(1))n$ vertices. We
generalise this result where we relax the restriction of packing families of
trees to families of graphs of any given non-trivial minor-closed class of
graphs.


title: Sequential subspace optimization for nonlinear inverse problems

abstract:
  In this work we discuss a method to adapt sequential subspace optimization
(SESOP), which has so far been developed for linear inverse problems in Hilbert
and Banach spaces, to the case of nonlinear inverse problems. We start by
revising the well-known technique for Hilbert spaces. In a next step, we
introduce a method using multiple search directions that are especially
designed to fit the nonlinearity of the forward operator. To this end, we
iteratively project the initial value onto stripes whose shape is determined by
the search direction, the nonlinearity of the operator and the noise level. We
additionally propose a fast algorithm that uses two search directions. Finally
we will show convergence and regularization properties for the presented
method.


title: Topological lasing and self-induced transparency in two level systems

abstract:
  The use of virtually lossless topologically isolated edge states may lead to
a novel class of thresholdless lasers operating without inversion. One needs
however to understand if topological states may be coupled to external
radiation and act as active cavities. We study a two-level topological
insulator and show that self-induced transparency pulses can directly excite
edge states. We simulate laser emission by a suitable designed topological
cavity, and show that it can emit tunable radiation. For a configuration of
sites following the off-diagonal Aubry-Andre-Harper model we solve the
Maxwell-Bloch equations in the time domain and provide a first principle
confirmation of topological lasers. Our results open the road to a new class of
light emitters with topological protection for applications ranging from
low-cost energetically-effective integrated lasers sources, also including
silicon photonics, to strong coupling devices for studying ultrafast quantum
processes with engineered vacuum.


title:
Quantum Fisher Information of an Open and Noisy System in the Steady
  State

abstract:
  We study the quantum Fisher information (QFI) per particle of an open (parti-
cles can enter and leave the system) and dissipative (far from thermodynamical
equilibrium) steady state system of two qubits in a noise which is decoherence.
We show the behavior of QFI per particle of the system due to changes of re-
set and decoherence parameters r and {\gamma} respectively. The parameter r is
the strength of the reset mechanism, {\gamma} is the strength of decoherence
and in our case it is dephasing channel. The parameters {\gamma} and r are real
numbers. We observe that the reset parameter must be bigger than decoherence
parameter. We have found that by choosing coupling parameter g as 5{\gamma} the
QFI per particle is 1.00226 which is greater than shot noise limit at {\gamma}
= 0.5 and r = 14 . Also the concurrence and negativity of the such state have
been calculated and they are found as 0.0992486 and 0.0496243 respectively. We
have shown that when the concurrence and negativity of some specific states
different than zero, which means the state is entangled, the QFI of the system
is greater than 1. The QFI per particle, concurrence and negativity shows that
the chosen case is weakly entangled. We discovered that the optimal direction
depends on the parameters r and {\gamma} and a change in the direction effects
the behavior of the QFI of the system.


title:
Modified interactions in a Floquet topological system on a square
  lattice and their impact on a bosonic fractional Chern insulator state

abstract:
  We propose a simple scheme for the realization of a topological quasienergy
band structure with ultracold atoms in a periodically driven optical square
lattice. It is based on a circular lattice shaking in the presence of a
superlattice that lowers the energy on every other site. The topological band
gap, which separates the two bands with Chern numbers $\pm 1$, is opened in a
way characteristic to Floquet topological insulators, namely, by terms of the
effective Hamiltonian that appear in subleading order of a high-frequency
expansion. These terms correspond to processes where a particle tunnels several
times during one driving period. The interplay of such processes with particle
interactions also gives rise to new interaction terms of several distinct
types. For bosonic atoms with on-site interactions, they include nearest
neighbor density-density interactions introduced at the cost of weakened
on-site repulsion as well as density-assisted tunneling. Using exact
diagonalization, we investigate the impact of the individual induced
interaction terms on the stability of a bosonic fractional Chern insulator
state at half filling of the lowest band.


title: Parasite Spreading in Spatial Ecological Multiplex Networks

abstract:
  Network ecology is a rising field of quantitative biology representing
ecosystems as complex networks. A suitable example is parasite spreading:
several parasites may be transmitted among their hosts through different
mechanisms, each one giving rise to a network of interactions. Modelling these
networked, ecological interactions at the same time is still an open challenge.
We present a novel spatially-embedded multiplex network framework for modelling
multi-host infection spreading through multiple routes of transmission. Our
model is inspired by T. cruzi, a parasite transmitted by trophic and vectorial
mechanisms. Our ecological network model is represented by a multiplex in which
nodes represent species populations interacting through a food web and a
parasite contaminative layer at the same time. We modelled an SI dynamics in
two different scenarios: a simple theoretical food web and an empirical one.
Our simulations in both scenarios show that the infection is more widespread
when both the trophic and the contaminative interactions are considered with
equal rates. This indicates that trophic and contaminative transmission may
have additive effects in real ecosystems. We also find that the ratio of
vectors-to-host in the community (i) crucially influences the infection spread,
(ii) regulates a percolating phase transition in the rate of parasite
transmission and (iii) increases the infection rate in hosts. By immunising the
same fractions of predator and prey populations, we show that the multiplex
topology is fundamental in outlining the role that each host species plays in
parasite transmission in a given ecosystem. We also show that the multiplex
models provide a richer phenomenology in terms of parasite spreading dynamics
compared to mono-layer models. Our work opens new challenges and provides new
quantitative tools for modelling multi-channel spreading in networked systems.

categories: q-bio.QM physics.bio-ph physics.soc-ph q-bio.PE


title:
Generalized quark-antiquark potentials from a $q$-deformed AdS$_5 \times
  $S$^5$ background

abstract:
  We study minimal surfaces with a single cusp in a $q$-deformed
AdS$_5\times$S$^5$ background. The cusp is composed of two half-lines with an
arbitrary angle and is realized on a surface specified in the deformed AdS$_5$.
The classical string solutions attached to this cusp are regarded as a
generalization of configurations studied by Drukker and Forini in the
undeformed case. By taking an antiparallel-lines limit, a quark-antiquark
potential for the $q$-deformed case is derived with a certain subtraction
scheme. The resulting potential becomes linear at short distances with a finite
deformation parameter. In particular, the linear behavior for the gravity dual
of noncommutative gauge theories can be reproduced as a special scaling limit.
Finally we study the near straight-line limit of the potential.


title:
Fast IDS Computing System Method and its Memristor Crossbar-based
  Hardware Implementation

abstract:
  Active Learning Method (ALM) is one of the powerful tools in soft computing
that is inspired by human brain capabilities in processing complicated
information. ALM, which is in essence an adaptive fuzzy learning method, models
a Multi-Input Single-Output (MISO) system with several Single-Input
Single-Output (SISO) subsystems. Ink Drop Spread (IDS) operator, which is the
main processing engine of this method, extracts useful features from the data
without complicated computations and provides stability and convergence as
well. Despite great performance of ALM in applications such as classification,
clustering, and modelling, an efficient hardware implementation has remained a
challenging problem. Large amount of memory required to store the information
of IDS planes as well as the high computational cost of the IDS computing
system are two main barriers to ALM becoming more popular. In this paper, a
novel learning method is proposed based on the idea of IDS, but with a novel
approach that eliminates the computational cost of IDS operator. Unlike
traditional approaches, our proposed method finds functions to describe the IDS
plane that eliminates the need for large amount of memory to a great extent.
Narrow Path and Spread, which are two main features used in the inference
engine of ALM, are then extracted from IDS planes with minimum amount of memory
usage and power consumption. Our proposed algorithm is fully compatible with
memristor-crossbar implementation that leads to a significant decrease in the
number of required memristors (from O(n^2) to O(3n)). Simpler algorithm and
higher speed make our algorithm suitable for applications where real-time
process, low-cost and small implementation are paramount. Applications in
clustering and function approximation are provided, which reveals the effective
performance of our proposed algorithm.


title:
The extinction and dust-to-gas structure of the planetary nebula NGC
  7009 observed with MUSE

abstract:
  The large field and wavelength range of MUSE is well suited to mapping
Galactic planetary nebulae (PN). The bright PN NGC 7009 was observed with MUSE
on the VLT during the Science Verification of the instrument in seeing of 0.6".
Emission line maps in hydrogen Balmer and Paschen lines were formed from
analysis of the MUSE cubes. The measured electron temperature and density from
the MUSE cube were employed to predict the theoretical hydrogen line ratios and
map the extinction distribution across the nebula. After correction for the
interstellar extinction to NGC 7009, the internal dust-to-gas ratio (A_V/N_H)
has been mapped for the first time in a PN. The extinction map of NGC 7009 has
considerable structure, broadly corresponding to the morphological features of
the nebula. A large-scale feature in the extinction map, consisting of a crest
and trough, occurs at the rim of the inner shell. The nature of this feature
was investigated and instrumental and physical causes considered; no convincing
mechanisms were identified to produce this feature, other than mass loss
variations in the earlier asymptotic giant branch phase. The dust-to-gas ratio
A_V/N_H increases from 0.7 times the interstellar value to >5 times from the
centre towards the periphery of the ionized nebula. The integrated A_V/N_H is
about 2 times the mean ISM value. It is demonstrated that extinction mapping
with MUSE provides a powerful tool for studying the distribution of PN internal
dust and the dust-to-gas ratio. (Abridged.)


title:
Critical behaviour of anisotropic magnets with quenched disorder:
  replica symmetry breaking studied by operator product expansion

abstract:
  We study critical behaviour of disordered magnets near four dimensions. We
consider the system with explicit cubic anisotropy and scalar disorder and that
with random direction of anisotropy axis. The quenched disorder is taken into
account by replica method. Using the method of operator product expansion, we
derive in the first order to $\epsilon$ approximation the renormalization group
equations taking into account possible replica symmetry breaking.


title:
Precise tuning of the Curie temperature of (Ga,Mn)As-based magnetic
  semiconductors by hole compensation: Support for valence-band ferromagnetism

abstract:
  For the prototype diluted ferromagnetic semiconductor (Ga,Mn)As, there is a
fundamental concern about the electronic states near the Fermi level, i.e.,
whether the Fermi level resides in a well-separated impurity band derived from
Mn doping (impurity-band model) or in the valence band that is already merged
with the Mn-derived impurity band (valence-band model). We investigate this
question by carefully shifting the Fermi level by means of carrier
compensation. We use helium-ion implantation, a standard industry technology,
to precisely compensate the hole doping of GaAs-based diluted ferromagnetic
semiconductors while keeping the Mn concentration constant. We monitor the
change of Curie temperature ($T_C$) and conductivity. For a broad range of
samples including (Ga,Mn)As and (Ga,Mn)(As,P) with various Mn and P
concentrations, we observe a smooth decrease of $T_C$ with carrier compensation
over a wide temperature range while the conduction is changed from metallic to
insulating. The existence of $T_C$ below 10\,K is also confirmed in heavily
compensated samples. Our experimental results are naturally explained within
the valence-band picture.


title: On the hidden charm pentaquark-s in $\Lambda_b \to J/\psi K^- p$ decay

abstract:
  In a previous work we presented a theoretical analysis of the $\Lambda_b \to
J/\psi K^- p$ reaction from where a recent experiment by the LHCb collaboration
at CERN claimed the existence of two hidden charm pentaquarks, $P_c(4380)^+$
and $P_c(4450)^+$. In that work we focused only on the $\Lambda(1405)$ and
$P_c(4450)^+$ signals and discussed the possible explanation of this pentaquark
state within the picture of a dynamical meson-baryon molecule made up mostly
from $\bar D^* \Sigma_c$ and $\bar D^* \Sigma^*_c$ components. In the present
work we improve upon the previous one by considering the total $K^- p$ and
$J/\psi p$ data including all the relevant resonances contributing to the
spectra, and discuss the possible nature of both $P_c(4380)^+$ and
$P_c(4450)^+$. We also discuss several important topics, like the effect of the
contact term in the reaction, the viability of reproducing the data without the
$P_c(4380)^+$ and the possible quantum numbers assignment to these pentaquarks.


title:
Probing the hard and intermediate states of X-ray binaries using short
  time-scale variability

abstract:
  Below an accretion rate of approximately a few per cent of the Eddington
accretion rate, X-ray binary systems are not usually found in the soft spectral
state. However, at accretion rates a factor of a few lower still, in the hard
state, there is another spectral transition which is well observed but not well
understood. Below ~0.5-1 per cent of the Eddington accretion rate (m_crit), the
spectral index hardens with increasing accretion rate, but above m_crit,
although still in the hard state, the spectral index softens with increasing
accretion rate. Here we use a combination of X-ray spectral fitting and a study
of short time-scale spectral variability to examine the behaviour of three
well-known X-ray binaries: Cygnus X-1, GX 339-4 and XTE J1118+480.
  In Cygnus X-1 we find separate hard and soft continuum components, and show
using root-mean-square (rms) spectra that the soft component dominates the
variability. The spectral transition at m_crit is clearly present in the
hard-state hardness-intensity diagrams of Cygnus X-1. Above m_crit, GX 339-4
shows similar softer-when-brighter behaviour at both long and short
time-scales. Similarly, XTE J1118+480, which remains well below m_crit, is
harder-when-brighter behaviour on all time-scales.
  We interpret these results in terms of two continuum components: a hard
power-law which dominates the spectra when the accretion rate is low, probably
arising from Comptonisation of cyclo-synchrotron photons from the corona, and a
soft power-law which dominates at higher accretion rates, arising from
Comptonisation of seed photons from the accretion disc.


title:
The effect of Ta oxygen scavenger layer on HfO$_2$-based resistive
  switching behavior: thermodynamic stability, electronic structure, and
  low-bias transport

abstract:
  Reversible resistive switching between high-resistance and low-resistance
states in metal-oxide-metal heterostructures makes them very interesting for
applications in random access memories. While recent experimental work has
shown that inserting a metallic "oxygen scavenger layer" between the positive
electrode and oxide improves device performance, the fundamental understanding
of how the scavenger layer modifies heterostructure properties is lacking. We
use density functional theory to calculate thermodynamic properties and
conductance of TiN/HfO$_2$/TiN heterostructures with and without Ta scavenger
layer. First, we show that Ta insertion lowers the formation energy of
low-resistance states. Second, while the Ta scavenger layer reduces the
Schottky barrier height in the high-resistance state by modifying the interface
charge at the oxide-electrode interface, the heterostructure maintains a high
resistance ratio between high- and low-resistance states. Finally, we show that
the low-bias conductance of device on-states becomes much less sensitive to the
spatial distribution of oxygen removed from the HfO$_2$ in the presence of the
Ta layer. By providing fundamental understanding of the observed improvements
with scavenger layers, we open a path to engineer interfaces with oxygen
scavenger layers to control and enhance device performance. In turn, this may
enable the realization of a non-volatile low-power memory technology with
concomitant reduction in energy consumption by consumer electronics and
significant benefits to society.


title:
Iteration-complexity of a Rockafellar's proximal method of multipliers
  for convex programming based on second-order approximations

abstract:
  This paper studies the iteration-complexity of a new primal-dual algorithm
based on Rockafellar's proximal method of multipliers (PMM) for solving smooth
convex programming problems with inequality constraints. In each step, either a
step of Rockafellar's PMM for a second-order model of the problem is computed
or a relaxed extragradient step is performed. The resulting algorithm is a
(large-step) relaxed hybrid proximal extragradient (r-HPE) method of
multipliers, which combines Rockafellar's PMM with the r-HPE method.


title: Differential modules over quadratic monomial algebras

abstract:
  We compare the so-called clock condition to the gradability of certain
differential modules over quadratic monomial algebras. For a stably hereditary
algebra or a gentle one-cycle algebra, these considerations show that the orbit
category of its bounded derived category with respect to a positive power of
the shift functor is triangulated if and only if the algebra is piecewise
hereditary.


title: Counting distinct dimer hex tilings

abstract:
  The combinatorics of tilings of a hexagon of integer side-length $n$ by 120
degree - 60 degree diamonds of side-length 1 has a long history, both directly
(as a problem of interest in thermodynamic models) and indirectly (through the
equivalence to plane partitions). Formulae as products of factorials have been
conjectured and, one by one, proven for the number of such tilings under each
of the symmetries of the hexagon. However, when this note was written the entry
for the number of distinct such tilings in the Online Encyclopedia of Integer
Sequences (OEIS) consisted of little more than a table for $0 \le n \le 4$ and
a brief discussion of those values. The aim of this note is to pull together
the relevant facts.


title:
Semi-supervised Clustering for Short Text via Deep Representation
  Learning

abstract:
  In this work, we propose a semi-supervised method for short text clustering,
where we represent texts as distributed vectors with neural networks, and use a
small amount of labeled data to specify our intention for clustering. We design
a novel objective to combine the representation learning process and the
k-means clustering process together, and optimize the objective with both
labeled data and unlabeled data iteratively until convergence through three
steps: (1) assign each short text to its nearest centroid based on its
representation from the current neural networks; (2) re-estimate the cluster
centroids based on cluster assignments from step (1); (3) update neural
networks according to the objective by keeping centroids and cluster
assignments fixed. Experimental results on four datasets show that our method
works significantly better than several other text clustering methods.


title: Widespread deuteration across the IRDC G035.39-00.33

abstract:
  Infrared Dark Clouds (IRDCs) are cold, dense regions that are usually found
within Giant Molecular Clouds (GMCs). Ongoing star formation within IRDCs is
typically still deeply embedded within the surrounding molecular gas.
Characterising the properties of relatively quiescent IRDCs may therefore help
us to understand the earliest phases of the star formation process. Studies of
local molecular clouds have revealed that deuterated species are enhanced in
the earliest phases of star formation. In this paper we test this towards IRDC
G035.39-00.33. We present an 80 arcsec by 140 arcsec map of the J=2-1
transition of N2D+, obtained with the IRAM-30m telescope. We find that N2D+ is
widespread throughout G035.39-00.33. Complementary observations of N2H+(1-0)
are used to estimate the deuterium fraction, N(N2D+)/N(N2H+). We report a mean
deuterium fraction of 0.04+-0.01, with a maximum of 0.09+-0.02. The mean
deuterium fraction is ~3 orders of magnitude greater than the interstellar
[D]/[H] ratio. High angular resolution observations are required to exclude
beam dilution effects of compact deuterated cores. Using chemical modelling, we
find that the average observed values of the deuterium fraction are in
agreement with an equilibrium deuterium fraction, given the general properties
of the cloud. This implies that the IRDC is at least ~3Myr old, which is ~8
times longer than the mean free-fall time of the observed deuterated region.


abstract:
  Cosmic ray primary particles initiate extended air showers (EAS) in the
atmosphere. The directions of these cosmic rays approximate a homogeneous
isotropic distribution. The HiSPARC experiment, consisting of a growing number
of measurement stations scattered over the Netherlands, Denmark and the United
Kingdom, detects EAS particles using scintillators. These detections facilitate
reconstructions of the direction of cosmic ray primaries.
  The acceptance of the HiSPARC experiment, limited due to the generating
mechanism of EASs in the atmosphere and the location of the measurement
stations, has been analysed.


title: A 3D spinorial view of 4D exceptional phenomena

abstract:
  We discuss a Clifford algebra framework for discrete symmetry groups (such as
reflection, Coxeter, conformal and modular groups), leading to a surprising
number of new results. Clifford algebras allow for a particularly simple
description of reflections via `sandwiching'. This extends to a description of
orthogonal transformations in general by means of `sandwiching' with Clifford
algebra multivectors, since all orthogonal transformations can be written as
products of reflections by the Cartan-Dieudonn\'e theorem. We begin by viewing
the largest non-crystallographic reflection/Coxeter group $H_4$ as a group of
rotations in two different ways -- firstly via a folding from the largest
exceptional group $E_8$, and secondly by induction from the icosahedral group
$H_3$ via Clifford spinors. We then generalise the second way by presenting a
construction of a 4D root system from any given 3D one. This affords a new --
spinorial -- perspective on 4D phenomena, in particular as the induced root
systems are precisely the exceptional ones in 4D, and their unusual
automorphism groups are easily explained in the spinorial picture; we discuss
the wider context of Platonic solids, Arnold's trinities and the McKay
correspondence. The multivector groups can be used to perform concrete
group-theoretic calculations, e.g. those for $H_3$ and $E_8$, and we discuss
how various representations can also be constructed in this Clifford framework;
in particular, representations of quaternionic type arise very naturally.


title:
Resistive method for measuring the disintegration speed of Prince
  Rupert's drops

abstract:
  We have successfully applied the resistance grid technique to measure the
disintegration speed in special type of glass objects, widely known as Prince
Rupert's drops. We use a digital oscilloscope and a simple electrical circuit,
glued to the surface of the drops, to detect the voltage changes, corresponding
to the breaks in the specific parts of the drops. The results obtained using
this method are in good qualitative and quantitative agreement with theoretical
predictions and previously published data. Moreover, the proposed experimental
setup doesn't include any expensive equipment (such as a high-speed camera) and
can therefore be widely used in high schools and universities.


title:
Theoretical optimal modulation frequencies for scattering parameter
  estimation and ballistic photon filtering in diffusive media

abstract:
  The efficiency of using intensity modulated light for estimation of
scattering properties of a turbid medium and for ballistic photon
discrimination is theoretically quantified in this article. Using the diffusion
model for modulated photon transport and considering a noisy quadrature
demodulation scheme, the minimum-variance bounds on estimation of parameters of
interest are analytically derived and analyzed. The existence of a
variance-minimizing optimal modulation frequency is shown and its evolution
with the properties of the intervening medium is derived and studied.
Furthermore, a metric is defined to quantify the efficiency of ballistic photon
filtering which may be sought when imaging through turbid media. The analytical
derivation of this metric shows that the minimum modulation frequency required
to attain significant ballistic discrimination depends only on the reduced
scattering coefficient of the medium in a linear fashion for a highly
scattering medium.


title: The Aid of Optical Studies in Understanding Millisecond Pulsar Binaries

abstract:
  A large number of new "black widow" and "redback" energetic millisecond
pulsars with irradiated stellar companions have been discovered through radio
and optical searches of unidentified \textit{Fermi} sources. Synchrotron
emission, from particles accelerated up to several TeV in the intrabinary
shock, exhibits modulation at the binary orbital period. Our simulated
double-peaked X-ray light curves modulated at the orbital period, produced by
relativistic Doppler-boosting along the intrabinary shock, are found to
qualitatively match those observed in many sources. In this model, redbacks and
transitional pulsar systems where the double-peaked X-ray light curve is
observed at inferior conjunction have intrinsically different shock geometry
than other millisecond pulsar binaries where the light curve is centered at
superior conjunction. We discuss, and advocate, how current and future optical
observations may aid in constraining the emission geometry, intrabinary shock
and the unknown physics of pulsar winds.


title: Coexistence of strong and weak coupling in ZnO nanowire cavities

abstract:
  We present a high quality two-dimensional cavity structure based on ZnO
nanowires coated with concentrical Bragg reflectors. The spatial mode
distribution leads to the simultaneous appearance of the weak and strong
coupling regime even at room temperature. Photoluminescence measurements agree
with FDTD simulations. Furthermore the ZnO core nanowires allow for the
observation of middle polariton branches between the A- and B-exciton ground
state resonances. Further, lasing emission up to room temperature is detected
in excitation dependent photoluminescence measurements.


title:
Testing the equivalence principle and Lorentz invariance with PeV
  neutrinos from blazar flares

abstract:
  It was recently proposed that a giant flare of the blazar PKS B1424-418 at
redshift $z=1.522$ is in association with a PeV-energy neutrino event detected
by IceCube. Based on this association we here suggest that the flight time
difference between the PeV neutrino and gamma-ray photons from blazar flares
can be used to constrain the violations of equivalence principle (EP) and the
Lorentz invariance for neutrinos. From the calculated Shapiro delay due to
clusters or superclusters in the nearby universe, we find that violation of the
equivalence principle for neutrinos and photons is constrained to an accuracy
of at least $10^{-5}$, which is two orders of magnitude tighter than the
constraint placed by MeV neutrinos from supernova 1987A. Lorentz invariance
violation (LIV) arises in various quantum-gravity theories, which predicts an
energy-dependent velocity of propagation in vacuum for photons and neutrinos.
We find that the association of the PeV neutrino with the gamma-ray outburst
set limits on the energy scale of possible LIV to $> 0.01 E_{pl}$ for linear
LIV models and $>6\times 10^{-8} E_{pl}$ for quadratic order LIV models, where
$E_{pl}$ is the Planck energy scale. These are the most stringent constraints
on neutrino LIV for subluminal neutrinos.


title: GodunovSPH with shear viscosity : implementation and tests

abstract:
  The acceleration and energy dissipation terms due to the shear viscosity have
been implemented and tested in GodunovSPH. The double summation method has been
employed to avoid the well known numerical noise of the second derivative in
particle based codes. The plane Couette flow with various initial and boundary
conditions have been used as tests, and the numerical and analytical results
show a good agreement. Not only the viscosity--only calculation, but the full
hydrodynamics simulations have been performed, and they show expected results
as well. The very low kinematic viscosity simulations show a turbulent pattern
when the Reynolds number exceeds $\sim$$10^2$. The critical value of the
Reynolds number at the transition point of the laminar and turbulent flows
coincides with the previous works approximately. A smoothed dynamic viscosity
has been suggested to describe the individual kinematic viscosity of particles.
The infinitely extended Couette flow which has two layers of different
viscosities has been simulated to check the smoothed dynamic viscosity, and the
result agrees well with the analytic solution. In order to compare the standard
SPH and GodunovSPH, the two layers test has been performed again with a density
contrast. GodunovSPH shows less dispersion than the standard SPH, but there is
no significant difference in the results. The results of the viscous ring
evolution has also been presented as well, and the numerical results agrees
with the analytic solution.


title: Preventive and Reactive Cyber Defense Dynamics Is Globally Stable

abstract:
  The recently proposed {\em cybersecurity dynamics} approach aims to
understand cybersecurity from a holistic perspective by modeling the evolution
of the global cybersecurity state. These models describe the interactions
between the various kinds of cyber defenses and the various kinds of cyber
attacks. We study a particular kind of cybersecurity dynamics caused by the
interactions between preventive and reactive defenses (e.g., filtering and
malware detection) against push- and pull-based cyber attacks (e.g., malware
spreading and "drive-by download" attacks). The dynamics was previously shown
to be globally stable in a {\em special} regime of the parameter universe, but
little is known beyond this special regime. In this paper, we resolve an open
problem in this domain by proving that the dynamics is globally stable in the
{\em entire} parameter universe (i.e., the dynamics always converges to a
unique equilibrium). We discuss the cybersecurity meanings and implications of
this theoretic result. We also prove that the dynamics converges {\em
exponentially} to the equilibrium except for a special parameter regime, in
which case the dynamics converges {\em polynomially}. Since it is often
difficult to compute the equilibrium, we propose new bounds of the equilibrium
and numerically show that these bounds are tighter than those proposed in the
literature.

categories: cs.CR cs.SI cs.SY math.DS physics.soc-ph


title: Towers and fibered products of model structures

abstract:
  Given a left Quillen presheaf of localized model structures, we study the
homotopy limit model structure on the associated category of sections. We focus
specifically on towers and fibered products (pullbacks) of model categories. As
applications we consider Postnikov towers of model categories, chromatic towers
of spectra and Bousfield arithmetic squares of spectra. For stable model
categories, we show that the homotopy fiber of a stable left Bousfield
localization is a stable right Bousfield localization.


title: Hidden in the background: a local approach to CMB anomalies

abstract:
  We investigate a framework aiming to provide a common origin for the
large-angle anomalies detected in the Cosmic Microwave Background (CMB), which
are hypothesized as the result of the statistical inhomogeneity developed by
different isocurvature fields of mass $m\sim H$ present during inflation. The
inhomogeneity arises as the combined effect of $(i)$ the initial conditions for
isocurvature fields (obtained after a fast-roll stage finishing many
$e$-foldings before cosmological scales exit the horizon), $(ii)$ their
inflationary fluctuations and $(iii)$ their coupling to other degrees of
freedom. Our case of interest is when these fields (interpreted as the
precursors of large-angle anomalies) leave an observable imprint only in
isolated patches of the Universe. When the latter intersect the last scattering
surface, such imprints arise in the CMB. Nevertheless, due to their
statistically inhomogeneous nature, these imprints are difficult to detect, for
they become hidden in the background similarly to the Cold Spot. We then
compute the probability that a single isocurvature field becomes inhomogeneous
at the end of inflation and find that, if the appropriate conditions are given
(which depend exclusively on the preexisting fast-roll stage), this probability
is at the percent level. Finally, we discuss several mechanisms (including the
curvaton and the inhomogeneous reheating) to investigate whether an initial
statistically inhomogeneous isocurvature field fluctuation might give rise to
some of the observed anomalies. In particular, we focus on the Cold Spot, the
power deficit at low multipoles and the breaking of statistical isotropy.


title: Canonical quantization of the covariant fields on de Sitter spacetimes

abstract:
  The properties of the covariant quantum fields on de Sitter spacetimes are
investigated focusing on the isometry generators and Casimir operators in order
to establish the equivalence among the covariant representations and the
unitary irreducible ones of the de Sitter isometry group. For the Dirac quantum
field it is shown that the spinor covariant representation, transforming the
Dirac field under de Sitter isometries, is equivalent with a direct sum of two
unitary irreducible representations of the $Sp(2,2)$ group, transforming alike
the particle and antiparticle field operators in momentum representation. Their
basis generators and Casimir operators are written down finding that the
covariant representations are equivalent with unitary irreducible ones from the
principal series whose canonical weights are determined by the fermion mass and
spin.


title: Unique factorization of principally polarized abelian varieties

abstract:
  Shimura proved that each principally polarized abelian variety over
$\mathbf{C}$ admits a unique factorization into irreducible principally
polarized abelian varieties. We give an exposition of his result, and
generalize to an arbitrary ground field $k$. If $k$ is separably closed, the
irreducible factors are in bijection with the irreducible components of a theta
divisor over $k$ giving rise to the polarization.


title: Graphene, plasmons and transformation optics

abstract:
  Here we study subwavelength gratings for coupling into graphene plasmons by
means of an an- alytical model based on transformation optics that is not
limited to very shallow gratings. We consider gratings that consist of a
periodic modulation of the charge density in the graphene sheet, and gratings
formed by this conductivity modulation together with a dielectric grating
placed in close vicinity of the graphene. Explicit expressions for the
dispersion relation of the plasmon po- laritons supported by the system, and
reflectance and transmittance under plane wave illumination are given. We
discuss the conditions for maximising the coupling between incident radiation
and plasmons in the graphene, finding the optimal modulation strength for a
conductivity grating.


title:
On generalized Eisenstein series and Ramanujan's formula for periodic
  zeta-functions

abstract:
  In this paper, transformation formulas for a large class of Eisenstein series
defined by \[
G(z,s;A_{\alpha},B_{\beta};r_{1},r_{2})=\sum\limits_{m,n=-\infty}^{\infty }\
\hspace{-0.19in}^{^{\prime}}\frac{f(\alpha m)f^{\ast}(\beta n)}
{((m+r_{1})z+n+r_{2})^{s}},\text{ }\operatorname{Re}(s)>2,\text{
}\operatorname{Im}(z)>0 \] are investigated for $s=1-r$, $r\in\mathbb{N}$. Here
$\left\{ f(n)\right\}$ and $\left\{ f^{\ast}(n)\right\}$, $-\infty<n<\infty$
are sequences of complex numbers with period $k>0$, and $A_{\alpha}=\left\{
f(\alpha n)\right\} $ and $B_{\beta}=\left\{ f^{\ast}(\beta n)\right\}$,
$\alpha,\beta\in\mathbb{Z}$. Appearing in the transformation formulas are
generalizations of Dedekind sums involving the periodic Bernoulli function.
Reciprocity law is proved for periodic Apostol-Dedekind sum outside of the
context of the transformation formulas. Furthermore, transformation formulas
are presented for $G(z,s;A_{\alpha},I;r_{1},r_{2})$ and $G(z,s;I,A_{\alpha
};r_{1},r_{2})$, where $I=\left\{ 1\right\}$. As an application of these
formulas, analogues of Ramanujan's formula for periodic zeta-functions are
derived.


title:
Four-jet production in single- and double-parton scattering within
  high-energy factorization

abstract:
  We perform a first study of 4-jet production in a complete high-energy
factorization (HEF) framework. We include and discuss contributions from both
single-parton scattering (SPS) and double-parton scattering (DPS). The
calculations are performed for kinematical situations relevant for two
experimental measurements (ATLAS and CMS) at the LHC. We compare our results to
those reported by the ATLAS and CMS collaborations for different sets of
kinematical cuts. The results of the HEF approach are compared with their
counterparts for collinear factorization. For symmetric cuts the DPS HEF result
is considerably smaller than the one obtained with collinear factorization. The
mechanism leading to this difference is of kinematical nature. We conclude that
an analysis of inclusive 4-jet production with asymmetric $p_T$-cuts below 50
GeV would be useful to enhance the DPS contribution relative to the SPS
contribution. In contrast to the collinear approach, the HEF approach nicely
describes the distribution of the $\Delta S$ variable, which involves all four
jets and their angular correlations.


title:
Observation of Helical Edge States and Fractional Quantum Hall Effect in
  a Graphene Electron-hole Bilayer

abstract:
  A quantum Hall edge state provides a rich foundation to study electrons in
1-dimension (1d) but is limited to chiral propagation along a single direction.
Here, we demonstrate a versatile platform to realize new 1d systems made by
combining quantum Hall edge states of opposite chiralities in a graphene
electron-hole bilayer. Using this approach, we engineer helical 1d edge
conductors where the counterpropagating modes are localized in separate
electron and hole layers by a tunable electric field. These helical conductors
exhibit strong nonlocal transport signals and suppressed backscattering due to
the opposite spin polarizations of the counterpropagating modes. Moreover, we
investigate these electron-hole bilayers in the fractional quantum Hall regime,
where we observe conduction through fractional and integer edge states of
opposite chiralities, paving the way towards the realization of 1d helical
systems with fractional quantum statistics.


title:
Momentum distributions and numerical methods for strongly interacting
  one-dimensional spinor gases

abstract:
  One-dimensional spinor gases with strong delta interaction fermionize and
form a spin chain. The spatial degrees of freedom of this atom chain can be
described by a mapping to spinless noninteracting fermions and the spin degrees
of freedom are described by a spin-chain model with nearest-neighbor
interactions. Here, we compute momentum and occupation-number distributions of
up to 16 strongly interacting spinor fermions and bosons as a function of their
spin imbalance, the strength of an externally applied magnetic field gradient,
the length of their spin, and for different excited states of the multiplet. We
show that the ground-state momentum distributions resemble those of the
corresponding noninteracting systems, apart from flat background distributions,
which extend to high momenta. Moreover, we show that the spin order of the spin
chain---in particular antiferromagnetic spin order---may be deduced from the
momentum and occupation-number distributions of the system. Finally, we present
efficient numerical methods for the calculation of the single-particle
densities and one-body density matrix elements and of the local exchange
coefficients of the spin chain for large systems containing more than 20
strongly interacting particles in arbitrary confining potentials.


title: The maximum weight stable set problem in $(P_6,\mbox{bull})$-free graphs

abstract:
  We present a polynomial-time algorithm that finds a maximum weight stable set
in a graph that does not contain as an induced subgraph an induced path on six
vertices or a bull (the graph with vertices $a, b, c, d, e$ and edges $ab, bc,
cd, be, ce$).


title:
Graph Regularized Low Rank Representation for Aerosol Optical Depth
  Retrieval

abstract:
  In this paper, we propose a novel data-driven regression model for aerosol
optical depth (AOD) retrieval. First, we adopt a low rank representation (LRR)
model to learn a powerful representation of the spectral response. Then, graph
regularization is incorporated into the LRR model to capture the local
structure information and the nonlinear property of the remote-sensing data.
Since it is easy to acquire the rich satellite-retrieval results, we use them
as a baseline to construct the graph. Finally, the learned feature
representation is feeded into support vector machine (SVM) to retrieve AOD.
Experiments are conducted on two widely used data sets acquired by different
sensors, and the experimental results show that the proposed method can achieve
superior performance compared to the physical models and other state-of-the-art
empirical models.


title: Fast Online k-nn Graph Building

abstract:
  In this paper we propose an online approximate k-nn graph building algorithm,
which is able to quickly update a k-nn graph using a flow of data points. One
very important step of the algorithm consists in using the current distributed
graph to search for the neighbors of a new node. Hence we also propose a
distributed partitioning method based on balanced k-medoids clustering, that we
use to optimize the distributed search process. Finally, we present the
improved sequential search procedure that is used inside each partition.
  We also perform an experimental evaluation of the different algorithms, where
we study the influence of the parameters and compare the result of our
algorithms to existing state of the art. This experimental evaluation confirms
that the fast online k-nn graph building algorithm produces a graph that is
highly similar to the graph produced by an offline exhaustive algorithm, while
it requires less similarity computations.


title: Codes Correcting a Burst of Deletions or Insertions

abstract:
  This paper studies codes that correct bursts of deletions. Namely, a code
will be called a $b$-burst-deletion-correcting code if it can correct a
deletion of any $b$ consecutive bits. While the lower bound on the redundancy
of such codes was shown by Levenshtein to be asymptotically $\log(n)+b-1$, the
redundancy of the best code construction by Cheng et al. is $b(\log (n/b+1))$.
In this paper we close on this gap and provide codes with redundancy at most
$\log(n) + (b-1)\log(\log(n)) +b -\log(b)$.
  We also derive a non-asymptotic upper bound on the size of
$b$-burst-deletion-correcting codes and extend the burst deletion model to two
more cases: 1) A deletion burst of at most $b$ consecutive bits and 2) A
deletion burst of size at most $b$ (not necessarily consecutive). We extend our
code construction for the first case and study the second case for $b=3,4$. The
equivalent models for insertions are also studied and are shown to be
equivalent to correcting the corresponding burst of deletions.


title:
Na\"ive Physics and Quantum Mechanics: The Cognitive Bias of Everett's
  Many-Worlds Interpretation

abstract:
  We discuss the role that intuitive theories of physics play in the
interpretation of quantum mechanics. We compare and contrast na\"ive physics
with quantum mechanics and argue that quantum mechanics is not just hard to
understand but that it is difficult to believe, often appearing magical in
nature. Quantum mechanics is often discussed in the context of "quantum
weirdness" and quantum entanglement is known as "spooky action at a distance."
This spookiness is more than just because quantum mechanics doesn't match
everyday experience; it ruffles the feathers of our na\"ive physics cognitive
module. In Everett's many-worlds interpretation of quantum mechanics, we
preserve a form of deterministic thinking that can alleviate some of the
perceived weirdness inherent in other interpretations of quantum mechanics, at
the cost of having the universe split into parallel worlds at every quantum
measurement. By examining the role cognitive modules play in interpreting
quantum mechanics, we conclude that the many-worlds interpretation of quantum
mechanics involves a cognitive bias not seen in the Copenhagen interpretation.


title: Understanding Visual Concepts with Continuation Learning

abstract:
  We introduce a neural network architecture and a learning algorithm to
produce factorized symbolic representations. We propose to learn these concepts
by observing consecutive frames, letting all the components of the hidden
representation except a small discrete set (gating units) be predicted from the
previous frame, and let the factors of variation in the next frame be
represented entirely by these discrete gated units (corresponding to symbolic
representations). We demonstrate the efficacy of our approach on datasets of
faces undergoing 3D transformations and Atari 2600 games.


title: Refinement types in Jolie

abstract:
  Jolie is the first language for microservices and it is currently dynamically
type checked. This paper considers the opportunity to integrate dynamic and
static type checking with the introduction of refinement types, verified via
SMT solver. The integration of the two aspects allows a scenario where the
static verification of internal services and the dynamic verification of
(potentially malicious) external services cooperates in order to reduce testing
effort and enhancing security.


title:
Quantum Oscillations at Integer and Fractional Landau Level Indices in
  ZrTe5

abstract:
  A three-dimensional (3D) Dirac semimetal (DS) is an analogue of graphene, but
with linear energy dispersion in all (three) momentum directions.3D DSs have
been a fertile playground in discovering novel quantum particles, for example
Weyl fermions, in solid state systems.Many 3D DSs (e.g., ZrTe5) were
theoretically predicted. We report here the results from the studies of
aberration-corrected scanning transmission electron microscopy and low
temperature magneto-transport measurements in exfoliated ZrTe5 thin
flakes.Several unique results were observed. First, an
anomalous-Hall-effect-like behavior was observed around zero magnetic field
(B).Second, a non-trivial Berry's phase of \pi\ was obtained from the Landau
level fan diagram of the Shubnikov-de Haas oscillations in the longitudinal
resistivity. Third, the longitudinal resistivity shows linear B field
dependence in the quantum limit. Most surprisingly, quantum oscillations were
observed at fractional Landau level indices N = 2/3 and 2/5, demonstrating
strong electron-electron interactions effects in ZrTe5.