title:
Sub-picosecond energy transfer from a highly intense THz pulse to water:
  a computational study based on the TIP4P/2005 model

abstract:
  The dynamics of ultrafast energy transfer to water clusters and to bulk water
by a highly intense, sub-cycle THz pulse of duration $\approx$~150~fs is
investigated in the context of force-field molecular dynamics simulations. We
focus our attention on the mechanisms by which rotational and translational
degrees of freedom of the water monomers gain energy from these sub-cycle
pulses with an electric field amplitude of up to about 0.6~V/{\AA}. It has been
recently shown that pulses with these characteristics can be generated in the
laboratory [PRL 112, 213901 (2014)]. Through their permanent dipole moment,
water molecules are acted upon by the electric field and forced off their
preferred hydrogen-bond network conformation. This immediately sets them in
motion with respect to one another as energy quickly transfers to their
relative center of mass displacements. We find that, in the bulk, the operation
of these mechanisms is strongly dependent on the initial temperature and
density of the system. In low density systems, the equilibration between
rotational and translational modes is slow due to the lack of collisions
between monomers. As the initial density of the system approaches 1~g/cm$^3$,
equilibration between rotational and translational modes after the pulse
becomes more efficient. In turn, low temperatures hinder the direct energy
transfer from the pulse to rotational motion owing to the resulting stiffness
of the hydrogen bond network. For small clusters of just a few water molecules
we find that fragmentation due to the interaction with the pulse is faster than
equilibration between rotations and translations, meaning that the latter
remain colder than the former after the pulse.


title: Multi-Agent System for Groundwater Depletion Using Game Theory

abstract:
  Groundwater is one of the most vital of all common pool resources throughout
the world. More than half of groundwater is used to grow crops. This research
models groundwater depletion patterns within a multi-agent system framework.
Irrigators are modeled as agents in the multi-agent system. The irrigation
strategies adopted by the agents are investigated using game theory. A set of
five irrigators, growing three crops: corn, sorghum and wheat, have been
considered in this study. To allow groundwater flow, these agents are assumed
to be located in adjoining farm lands. Irrigators are modeled selfish agents
that strategize their irrigation patterns in order to maximize their own
utilities, i.e. the difference between the total revenue obtained from crop
sales and the costs incurred, including groundwater extraction costs. Due to
groundwater flow, and have no incentive to conserve groundwater. This leads to
unsustainable depletion of the resource under Nash equilibrium, when no
irrigator can increase its utility by unilaterally changing its strategy. All
parameters in this research are representative of Kansas. Recorded
environmental and economic data of the region, along with the DSSAT software,
have been used to obtain these futuristic projections. One of the emergent
phenomena of the simulations is the adoption of crop rotation patterns by the
irrigators to conserve groundwater. The irrigators grow corn, which is a more
profitable yet water intensive crop in one year, and in the next, conserve
water by growing sorghum instead. Another emergent outcome of this research is
the viability of LEMAs. When the irrigators are subject to LEMA-level limits on
groundwater use, there is a slight increase in the aggregate utility of the
LEMA.


title:
A hybrid heuristic algorithm with application to a graphical interface
  for vehicle routing optimization in an agricultural cooperative

abstract:
  This work considers the problem of optimize the routes of the vehicles used
by a real agricultural cooperative that distributes animal feed among the
partners. Because solving the exact model is computationally burdensome, we
propose to implement heuristic algorithms. Thus, firstly an initial solution is
obtained through an insertion heuristic algorithm. Secondly, we design a
simulated annealing algorithm for possible improvements on the initial
solution. Finally, we built a graphical interface to quickly and easily
interact with the system.


title: Matrix-vector representation of various solution concepts

abstract:
  A unified matrix-vector representation is developed of such solution concepts
as the core, the uncovered, the uncaptured, the minimal weakly stable, the
minimal undominated, the minimal dominant and the untrapped sets. We also
propose several new versions of solution sets.


title: 3D WKB solution for fast magnetoacoustic wave behaviour around an X-line

abstract:
  We study the propagation of a fast magnetoacoustic wave in a 3D magnetic
field created from two magnetic dipoles. The magnetic topology contains an
X-line. We aim to contribute to the overall understanding of MHD wave
propagation within inhomogeneous media, specifically around X-lines. We
investigate the linearised, 3D MHD equations under the assumptions of ideal and
cold plasma. We utilise the WKB approximation and Charpit's method during our
investigation. It is found that the behaviour of the fast magnetoacoustic wave
is entirely dictated by the local, inhomogeneous, equilibrium Alfv\'en speed
profile. All parts of the wave experience refraction during propagation, where
the magnitude of the refraction effect depends on the location of an individual
wave element within the inhomogeneous magnetic field. The X-line, along which
the Alfv\'en speed is identically zero, acts as a focus for the refraction
effect. There are two main types of wave behaviour: part of the wave is either
trapped by the X-line or escapes the system, and there exists a critical
starting region around the X-line that divides these two types of behaviour.
For the set-up investigated, it is found that $15.5\%$ of the fast wave energy
is trapped by the X-line. We conclude that linear, $\beta=0$ fast
magnetoacoustic waves can accumulate along X-lines and thus these will be
specific locations of fast wave energy deposition and thus preferential
heating. The work here highlights the importance of understanding the magnetic
topology of a system. We also demonstrate how the 3D WKB technique described in
this paper can be applied to other magnetic configurations.


title: Analytic continuation of the rotating black hole state counting

abstract:
  In loop quantum gravity, a spherical black hole can be described in terms of
a Chern-Simons theory on a punctured 2-sphere. The sphere represents the
horizon. The punctures are the edges of spin-networks in the bulk which cross
the horizon and carry quanta of area. One can generalize this construction and
model a rotating black hole by adding an extra puncture colored with the
angular momentum J in the 2-sphere. We compute the entropy of rotating black
holes in this model and study its semi-classical limit. After performing an
analytic continuation which sends the Barbero-Immirzi parameter to +/- i, we
show that the leading order term in the semi-classical expansion of the entropy
reproduces the Bekenstein-Hawking law independently of the value of J.


title: On the Optimal Boolean Function for Prediction under Quadratic Loss

abstract:
  Suppose $Y^{n}$ is obtained by observing a uniform Bernoulli random vector
$X^{n}$ through a binary symmetric channel. Courtade and Kumar asked how large
the mutual information between $Y^{n}$ and a Boolean function
$\mathsf{b}(X^{n})$ could be, and conjectured that the maximum is attained by a
dictator function. An equivalent formulation of this conjecture is that
dictator minimizes the prediction cost in a sequential prediction of $Y^{n}$
under logarithmic loss, given $\mathsf{b}(X^{n})$. In this paper, we study the
question of minimizing the sequential prediction cost under a different
(proper) loss function - the quadratic loss. In the noiseless case, we show
that majority asymptotically minimizes this prediction cost among all Boolean
functions. We further show that for weak noise, majority is better than
dictator, and that for strong noise dictator outperforms majority. We
conjecture that for quadratic loss, there is no single sequence of Boolean
functions that is simultaneously (asymptotically) optimal at all noise levels.


title: Modeling analysis and optimization for European network data merging

abstract:
  In this paper, the problem of building a consistent European network state
based on the data provided by different Transmission System Operators (TSOs) is
addressed. A hierarchical merging procedure is introduced and consists in the
resolution of several Optimal Power Flow problems (OPFs). Results on the
European network demonstrate the interest of this procedure on real-life cases
and highlight the benefits of using a hierarchical multi-objective approach.


title:
Acoustic scene classification using convolutional neural network and
  multiple-width frequency-delta data augmentation

abstract:
  In recent years, neural network approaches have shown superior performance to
conventional hand-made features in numerous application areas. In particular,
convolutional neural networks (ConvNets) exploit spatially local correlations
across input data to improve the performance of audio processing tasks, such as
speech recognition, musical chord recognition, and onset detection. Here we
apply ConvNet to acoustic scene classification, and show that the error rate
can be further decreased by using delta features in the frequency domain. We
propose a multiple-width frequency-delta (MWFD) data augmentation method that
uses static mel-spectrogram and frequency-delta features as individual input
examples. In addition, we describe a ConvNet output aggregation method designed
for MWFD augmentation, folded mean aggregation, which combines output
probabilities of static and MWFD features from the same analysis window using
multiplication first, rather than taking an average of all output
probabilities. We describe calculation results using the DCASE 2016 challenge
dataset, which shows that ConvNet outperforms both of the baseline system with
hand-crafted features and a deep neural network approach by around 7%. The
performance was further improved (by 5.7%) using the MWFD augmentation together
with folded mean aggregation. The system exhibited a classification accuracy of
0.831 when classifying 15 acoustic scenes.


title: On The Non-Existence of CR-Regular Embeddings of $S^5$

abstract:
  In this article, we show that there exists no CR-regular embedding of the
5-sphere $S^5$ into $\mathbb{C}^4$, and also obtain analogous results for
embeddings of higher dimensional spheres into complex space.


title: Finite Length Performance of Random Slotted ALOHA Strategies

abstract:
  Multiple connected devices sharing common wireless resources might create
interference if they access the channel simultaneously. Medium access control
(MAC) protocols gener- ally regulate the access of the devices to the shared
channel to limit signal interference. In particular, irregular repetition
slotted ALOHA (IRSA) techniques can achieve high-throughput performance when
interference cancellation methods are adopted to recover from collisions. In
this work, we study the finite length performance for IRSA schemes by building
on the analogy between successive interference cancellation and iterative
belief- propagation on erasure channels. We use a novel combinatorial
derivation based on the matrix-occupancy theory to compute the error
probability and we validate our method with simulation results.


title:
Spatially Resolved Fourier Transform Spectroscopy in the Extreme
  Ultraviolet

abstract:
  Coherent extreme ultraviolet (XUV) radiation produced by table-top
high-harmonic generation (HHG) sources provides a wealth of possibilities in
research areas ranging from attosecond physics to high resolution coherent
imaging. However, it remains challenging to fully exploit the coherence of such
sources for interferometry and Fourier transform spectroscopy (FTS). This is
due to the need for a measurement system that is stable at the level of a
wavelength fraction, yet allowing a controlled scanning of time delays. Here we
demonstrate XUV interferometry and FTS in the 17-55 nm wavelength range using
an ultrastable common-path interferometer suitable for high-intensity laser
pulses that drive the HHG process. This approach enables the generation of
fully coherent XUV pulse pairs with sub-attosecond timing variation, tunable
time delay and a clean Gaussian spatial mode profile. We demonstrate the
capabilities of our XUV interferometer by performing spatially resolved FTS on
a thin film composed of titanium and silicon nitride.


title:
Convergence rates of Kernel Conjugate Gradient for random design
  regression

abstract:
  We prove statistical rates of convergence for kernel-based least squares
regression from i.i.d. data using a conjugate gradient algorithm, where
regularization against overfitting is obtained by early stopping. This method
is related to Kernel Partial Least Squares, a regression method that combines
supervised dimensionality reduction with least squares projection. Following
the setting introduced in earlier related literature, we study so-called "fast
convergence rates" depending on the regularity of the target regression
function (measured by a source condition in terms of the kernel integral
operator) and on the effective dimensionality of the data mapped into the
kernel space. We obtain upper bounds, essentially matching known minimax lower
bounds, for the $\mathcal{L}^2$ (prediction) norm as well as for the stronger
Hilbert norm, if the true regression function belongs to the reproducing kernel
Hilbert space. If the latter assumption is not fulfilled, we obtain similar
convergence rates for appropriate norms, provided additional unlabeled data are
available.


title: Moving inhomogeneous envelopes of stars

abstract:
  Massive stars are extremely luminous and drive strong winds, blowing a large
part of their matter into the galactic environment before they finally explode
as a supernova. Quantitative knowledge of massive star feedback is required to
understand our Universe as we see it. Traditionally, massive stars have been
studied under the assumption that their winds are homogeneous and stationary,
largely relying on the Sobolev approximation. However, observations with the
newest instruments, together with progress in model calculations, ultimately
dictate a cardinal change of this paradigm: stellar winds are highly
inhomogeneous. Hence, we are now advancing to a new stage in our understanding
of stellar winds. Using the foundations laid by V.V. Sobolev and his school, we
now update and further develop the stellar spectral analysis techniques. New
sophisticated 3-D models of radiation transfer in inhomogeneous expanding media
elucidate the physics of stellar winds and improve classical empiric mass-loss
rate diagnostics. Applications of these new techniques to multiwavelength
observations of massive stars yield consistent and robust stellar wind
parameters.


title:
Critical properties of weakly interacting Bose gases as modified by a
  harmonic confinement

abstract:
  The critical properties of the phase transition from a normal gas to a BEC
(superfluid) of a harmonically confined Bose gas are addressed with the
knowledge of an equation of state of the underlying homogeneous Bose fluid. It
is shown that while the presence of the confinement trap arrests the usual
divergences of the isothermal compressibility and heat capacities, the critical
behavior manifests itself now in the divergence of derivatives of the mentioned
susceptibilities. This result is illustrated with a mean-field like model of an
equation of state for the homogeneous particle density as a function of the
chemical potential and temperature of the gas. The model assumes the form of an
ideal Bose gas in the normal fluid while in the superfluid state a function is
proposed such that, both, asymptotically reaches the Thomas-Fermi solution of a
weakly interacting Bose gas at large densities and low temperatures and, at the
transition, matches the critical properties of the ideal Bose gas. With this
model we obtain the {\it global} thermodynamics of the harmonically confined
gas, from which we analyze its critical properties. We discuss how these
properties can be experimentally tested.


title:
The band spectrum of the periodic airy-schrodinger operator on the real
  line

abstract:
  We introduce the periodic Airy-Schr\"odinger operator and we study its band
spectrum. This is an example of an explicitly solvable model with a periodic
potential which is not differentiable at its minima and maxima. We define a
semiclassical regime in which the results are stated for a fixed value of the
semiclassical parameter and are thus estimates instead of asymptotic results.
We prove that there exists a sequence of explicit constants, which are zeroes
of classical functions, giving upper bounds of the semiclassical parameter for
which the spectral bands are in the semiclassical regime. We completely
determine the behaviour of the edges of the first spectral band with respect to
the semiclassical parameter. Then, we investigate the spectral bands and gaps
situated in the range of the potential. We prove precise estimates on the
widths of these spectral bands and these spectral gaps and we determine an
upper bound on the integrated spectral density in this range. Finally, in the
semiclassical regime, we get estimates of the edges of every spectral bands and
thus of the widths of every spectral bands and spectral gaps.


title: Estimation of the global regularity of a multifractional Brownian motion

abstract:
  This paper presents a new estimator of the global regularity index of a
multifractional Brownian motion. Our estimation method is based upon a ratio
statistic, which compares the realized global quadratic variation of a
multifractional Brownian motion at two different frequencies. We show that a
logarithmic transformation of this statistic converges in probability to the
minimum of the Hurst function, which is, under weak assumptions, identical to
the global regularity index of the path.


title: Universal large deviations for Kac polynomials

abstract:
  We prove the universality of the large deviations principle for the empirical
measures of zeros of random polynomials whose coefficients are i.i.d. random
variables possessing a density with respect to the Lebesgue measure on C, R or
R + , under the assumption that the density does not vanish too fast at zero
and decays at least as exp --|x| $\rho$ , $\rho$ \textgreater{} 0, at infinity.


title: Grown-up stars physics with MATISSE

abstract:
  MATISSE represents a great opportunity to image the environment around
massive and evolved stars. This will allow one to put constraints on the
circumstellar structure, on the mass ejection of dust and its reorganization ,
and on the dust-nature and formation processes. MATISSE measurements will often
be pivotal for the understanding of large multiwavelength datasets on the same
targets collected through many high-angular resolution facilities at ESO like
sub-millimeter interferometry (ALMA), near-infrared adaptive optics (NACO,
SPHERE), interferometry (PIONIER, GRAVITY), spectroscopy (CRIRES), and
mid-infrared imaging (VISIR). Among main sequence and evolved stars, several
cases of interest have been identified that we describe in this paper.


title:
Constrained hyperbolic divergence cleaning in smoothed particle
  magnetohydrodynamics with variable cleaning speeds

abstract:
  We present an updated constrained hyperbolic/parabolic divergence cleaning
algorithm for smoothed particle magnetohydrodynamics (SPMHD) that remains
conservative with wave cleaning speeds which vary in space and time. This is
accomplished by evolving the quantity $\psi / c_h$ instead of $\psi$. Doing so
allows each particle to carry an individual wave cleaning speed, $c_h$, that
can evolve in time without needing an explicit prescription for how it should
evolve, preventing circumstances which we demonstrate could lead to runaway
energy growth related to variable wave cleaning speeds. This modification
requires only a minor adjustment to the cleaning equations and is trivial to
adopt in existing codes. Finally, we demonstrate that our constrained
hyperbolic/parabolic divergence cleaning algorithm, run for a large number of
iterations, can reduce the divergence of the field to an arbitrarily small
value, achieving $\nabla \cdot B=0$ to machine precision.

categories: astro-ph.IM astro-ph.CO astro-ph.GA astro-ph.SR


title:
A Modular Data Acquisition System using the 10 GSa/s PSEC4 Waveform
  Recording Chip

abstract:
  We describe a modular multi-channel data acquisition system based on the 5-15
Gigasample-per-second waveform-recording PSEC4 chip. The system architecture
incorporates two levels of hardware with FPGA-embedded system control and
in-line data processing. The front-end unit is a 30-channel circuit board that
holds five PSEC4 ASICs, a clock jitter cleaner, and a control FPGA. The analog
bandwidth of the front-end signal path is 1.5 GHz. Each channel has an on-chip
threshold-level discriminator that is monitored in the FPGA, from which a
flexible on-board trigger decision can be formed. To instrument larger channel
counts, a `back-end' 6U VME32 control card has been designed. Called the
'Central Card', it incorporates an Altera Arria-V FPGA that manages up to 8
front-end cards using one or two CAT5 network cables per board, which transmits
the clock and communicates data packets over a custom serial protocol. Data can
be read from the Central Card via USB, Ethernet, or dual SFP links, in addition
to the VME interface. The Central Card can be configured as either Master or
Slave, allowing one Master to receive data from up to 8 Slaves, with each Slave
managing 8 30-channel front-end cards, allowing a single VME crate to control
up to 1920 channels of the PSEC4 chip.


title:
Littlewood-Richardson coefficients for Grothendieck polynomials from
  integrability

abstract:
  We study the Littlewood-Richardson coefficients of double Grothendieck
polynomials indexed by Grassmannian permutations. Geometrically, these are the
structure constants of the equivariant $K$-theory ring of Grassmannians.
Representing the double Grothendieck polynomials as partition functions of an
integrable vertex model, we use its Yang-Baxter equation to derive a series of
product rules for the former polynomials and their duals. The
Littlewood-Richardson coefficients that arise can all be expressed in terms of
puzzles without gashes, which generalize previous puzzles obtained by
Knutson-Tao and Vakil.


title: Enlightening Deep Neural Networks with Knowledge of Confounding Factors

abstract:
  Deep learning techniques have demonstrated significant capacity in modeling
some of the most challenging real world problems of high complexity. Despite
the popularity of deep models, we still strive to better understand the
underlying mechanism that drives their success. Motivated by observations that
neurons in trained deep nets predict attributes indirectly related to the
training tasks, we recognize that a deep network learns representations more
general than the task at hand to disentangle impacts of multiple confounding
factors governing the data, in order to isolate the effects of the concerning
factors and optimize a given objective. Consequently, we propose a general
framework to augment training of deep models with information on auxiliary
explanatory data variables, in an effort to boost this disentanglement and
train deep networks that comprehend the data interactions and distributions
more accurately, and thus improve their generalizability. We incorporate
information on prominent auxiliary explanatory factors of the data population
into existing architectures as secondary objective/loss blocks that take inputs
from hidden layers during training. Once trained, these secondary circuits can
be removed to leave a model with the same architecture as the original, but
more generalizable and discerning thanks to its comprehension of data
interactions. Since pose is one of the most dominant confounding factors for
object recognition, we apply this principle to instantiate a pose-aware deep
convolutional neural network and demonstrate that auxiliary pose information
indeed improves the classification accuracy in our experiments on SAR target
classification tasks.


title: A quantum teleportation experiment for undergraduate students

abstract:
  With the rapid progress of quantum information these recent years, it becomes
more and more relevant to dedicate efforts in introducing this research topic
to undergraduate students. However, as if in various fields of physics the
theoretical learning is closely accompanied with experimental illustrations,
such a teaching method can be expensive to organise for quantum information. We
propose one way to circumvent these difficulties by using the recently made
available 5-qubit quantum processor of IBM, in order to illustrate quantum
information tasks, by actually implementing them on the superconducting chip
through the web interface of the IBM Quantum Experience. We focus on the
realization of a quantum teleportation protocol on this device, analyze the
results and discuss the issues encountered, providing a complete analysis of
this software as a pedagogical tool.


title:
Translating Bayesian Networks into Entity Relationship Models, Extended
  Version

abstract:
  Big data analytics applications drive the convergence of data management and
machine learning. But there is no conceptual language available that is spoken
in both worlds. The main contribution of the paper is a method to translate
Bayesian networks, a main conceptual language for probabilistic graphical
models, into usable entity relationship models. The transformed representation
of a Bayesian network leaves out mathematical details about probabilistic
relationships but unfolds all information relevant for data management tasks.
As a real world example, we present the TopicExplorer system that uses Bayesian
topic models as a core component in an interactive, database-supported web
application. Last, we sketch a conceptual framework that eases machine learning
specific development tasks while building big data analytics applications.


title:
GRB 090510: a genuine short-GRB from a binary neutron star coalescing
  into a Kerr-Newman black hole

abstract:
  In a new classification of merging binary neutron stars (NSs) we separate
short gamma-ray bursts (GRBs) in two sub-classes. The ones with
$E_{iso}\lesssim10^{52}$ erg coalesce to form a massive NS and are indicated as
short gamma-ray flashes (S-GRFs). The hardest, with $E_{iso}\gtrsim10^{52}$
erg, coalesce to form a black hole (BH) and are indicated as genuine short-GRBs
(S-GRBs). Within the fireshell model, S-GRBs exhibit three different
components: the P-GRB emission, observed at the transparency of a
self-accelerating baryon-$e^+e^-$ plasma; the prompt emission, originating from
the interaction of the accelerated baryons with the circumburst medium; the
high-energy (GeV) emission, observed after the P-GRB and indicating the
formation of a BH. GRB 090510 gives the first evidence for the formation of a
Kerr BH or, possibly, a Kerr-Newman BH. Its P-GRB spectrum can be fitted by a
convolution of thermal spectra whose origin can be traced back to an axially
symmetric dyadotorus. A large value of the angular momentum of the newborn BH
is consistent with the large energetics of this S-GRB, which reach in the
1--10000 keV range $E_{iso}=(3.95\pm0.21)\times10^{52}$ erg and in the 0.1--100
GeV range $E_{LAT}=(5.78\pm0.60)\times10^{52}$ erg, the most energetic GeV
emission ever observed in S-GRBs. The theoretical redshift $z_{th}=0.75\pm0.17$
that we derive from the fireshell theory is consistent with the spectroscopic
measurement $z=0.903\pm0.003$, showing the self-consistency of the theoretical
approach. All S-GRBs exhibit GeV emission, when inside the Fermi-LAT field of
view, unlike S-GRFs, which never evidence it. The GeV emission appears to be
the discriminant for the formation of a BH in GRBs, confirmed by their observed
overall energetics.


title: A Degenerate Bogdanov-Takens Normal Form for FLRW Cosmologies

abstract:
  In this paper, we first show that the Einstein field equations for all
perfect-fluid FLRW cosmologies can be written as a planar dynamical system with
the equation of state parameter $w$ and cosmological constant $\Lambda$ as
parameters. An important equilibrium point of this dynamical system is the
origin which represents Minkowski spacetime. It is shown that the Einstein
field equations in a neigbourhood of this point are equivalent to a degenerate
Bogdanov-Takens normal form. This normal form admits a set of equilibrium
points that describes a set of solutions to the Einstein field equations that
have a constant rate of expansion, negative spatial curvature, zero
cosmological constant and dust.


title: Bosonic Decays of Charged Higgs Bosons in a 2HDM Type-I

abstract:
  In this study, we focus on the bosonic decays of light charged Higgs bosons
in the 2-Higgs Doublet Model (2HDM) Type-I. We quantify the Branching Ratios
(BRs) of the $H^\pm \to W^\pm h$ and $H^\pm\to W^\pm A$ channels and show that
they could be substantial over several areas of the parameter space of the 2HDM
Type-I that are still allowed by Large Hadron Collider (LHC) and other
experimental data as well as theoretical constraints. We suggest that $H^\pm
\to W^\pm h$ and/or $H^\pm \to W^\pm A$ could be used as a feasible discovery
channel alternative to $H^\pm \to \tau\nu$.


title: Monotone-light factorizations in coarse geometry

abstract:
  We introduce large scale analogues of topological monotone and light maps,
which we call coarsely monotone and coarsely light maps respectively. We show
that these two classes of maps constitute a factorization system on the coarse
category. We also show how coarsely monotone maps arise from a reflection in a
similar way to classically monotone maps, and prove that coarsely monotone maps
are stable under those pullbacks which exist in the coarse category. For the
case of maps between proper metric spaces, we exhibit some connections between
the coarse and classical notions of monotone and light using the Higson corona.
Finally, we look at some coarse properties which are preserved by coarsely
light maps such as finite asymptotic dimension and exactness, and make some
remarks on the situation for groups and group homomorphisms.


title: The role of quantum measurement in stochastic thermodynamics

abstract:
  This article sets up a new formalism to investigate stochastic thermodynamics
in the quantum regime, where stochasticity and irreversibility primarily come
from quantum measurement. In the absence of any bath, we define a purely
quantum component to heat exchange, that corresponds to energy fluctuations
caused by measurement back-action. Energetic and entropic signatures of
measurement induced irreversibility are then investigated for canonical
experiments of quantum optics, and the energetic cost of counter-acting
decoherence is characterized on a simple state-stabilizing protocol. By placing
quantum measurement in a central position, our formalism contributes to bridge
a gap between experimental quantum optics and quantum thermodynamics.


title: Interpretation of Axial Resonances in J/psi-phi at LHCb

abstract:
  We suggest that the J/psi phi structures observed by LHCb can be fitted in
two tetraquak multiplets, the S-wave ground state and the first radial
excitation, with composition [cs][cbar sbar]. When compared to the previously
identified [cq][cbar qbar] multiplet, the observed masses agree with what
expected for a multiplet with q -->s. We propose the X(4274), fitted by LHCb
with a single 1^++ resonance, to correspond rather to two, almost degenerate,
unresolved lines with J^PC = 0^++, 2^++. Masses of missing particles in the 1S
and 2S multiplets are predicted.


title: Competition between Bose Einstein Condensation and spin dynamics

abstract:
  We study the impact of spin-exchange collisions on the dynamics of
Bose-Einstein condensation, by rapidly cooling a chromium multi-component Bose
gas. Despite relatively strong spin-dependent interactions, the critical
temperature for Bose-Einstein condensation is reached before the spin-degrees
of freedom fully thermalize. The increase in density due to Bose-Einstein
condensation then triggers spin dynamics, hampering the formation of
condensates in spin excited states. Small metastable spinor condensates are
nevertheless produced, and manifest strong spin fluctuations.


title: A Cyber Infrastructure for the SKA Telescope Manager

abstract:
  The Square Kilometre Array Telescope Manager (SKA TM) will be responsible for
assisting the SKA Operations and Observation Management, carrying out System
diagnosis and collecting Monitoring & Control data from the SKA sub-systems and
components. To provide adequate compute resources, scalability, operation
continuity and high availability, as well as strict Quality of Service, the TM
cyber-infrastructure (embodied in the Local Infrastructure - LINFRA) consists
of COTS hardware and infrastructural software (for example: server monitoring
software, host operating system, virtualization software, device firmware),
providing a specially tailored Infrastructure as a Service (IaaS) and Platform
as a Service (PaaS) solution. The TM infrastructure provides services in the
form of computational power, software defined networking, power, storage
abstractions, and high level, state of the art IaaS and PaaS management
interfaces. This cyber platform will be tailored to each of the two SKA Phase 1
telescopes (SKA_MID in South Africa and SKA_LOW in Australia) instances, each
presenting different computational and storage infrastructures and conditioned
by location. This cyber platform will provide a compute model enabling TM to
manage the deployment and execution of its multiple components (observation
scheduler, proposal submission tools, M&C components, Forensic tools and
several Databases, etc). In this sense, the TM LINFRA is primarily focused
towards the provision of isolated instances, mostly resorting to virtualization
technologies, while defaulting to bare hardware if specifically required due to
performance, security, availability, or other requirement.


title:
Anomalous transport in cellular flows: The role of initial conditions
  and aging

abstract:
  We consider the diffusion-advection problem in two simple cellular flow
models (often invoked as examples for subdiffusive tracer's motion) and
concentrate on the intermediate time range, in which the tracer's motion indeed
may show subdiffusion. We have performed extensive numerical simulations of the
systems under different initial conditions, and show that the pure
intermediate-time subdiffusion regime is only evident when the particles start
at the border between different cells, i.e. at the separatrix, and is less
pronounced or absent for other initial conditions. The motion moreover shows
quite peculiar aging properties which are also mirrored in the behavior of the
time-averaged mean squared displacement for single trajectories. This kind of
behavior is due to the complex motion of tracers trapped inside the cell, and
is absent in classical models based on continuous time random walks (CTRW) with
no dynamics in the trapped state.


title: Finite depth gravity water waves in holomorphic coordinates

abstract:
  In this article we consider irrotational gravity water waves with finite
bottom. Our goal is two-fold. First, we represent the equations in holomorphic
coordinates and discuss the local well-posedness of the problem in this
context. Second, we consider the small data problem and establish cubic
lifespan bounds for the solutions. Our results are uniform in the infinite
depth limit, and match the earlier infinite depth result of
Hunter-Ifrim-Tataru.


title: Tail protection for long investors: Trend convexity at work

abstract:
  The performance of trend following strategies can be ascribed to the
difference between long-term and short-term realized variance. We revisit this
general result and show that it holds for various definitions of trend
strategies. This explains the positive convexity of the aggregate performance
of Commodity Trading Advisors (CTAs) which -- when adequately measured -- turns
out to be much stronger than anticipated. We also highlight interesting
connections with so-called Risk Parity portfolios. Finally, we propose a new
portfolio of strangle options that provides a pure exposure to the long-term
variance of the underlying, offering yet another viewpoint on the link between
trend and volatility.


title: Has the QCD critical point been observed at RHIC? - A Rebuttal

abstract:
  This note rebuts an old, but recurring claim by Antoniou, Davis and Diakonos
[1] that the critical point and associated critical exponents reported in Ref.
[2], is based on an erroneous treatment of scaling relations near the critical
point.


title: On time

abstract:
  This note describes the restoration of time in one-dimensional
parameterization-invariant (hence timeless) models, namely the
classically-equivalent Jacobi action and gravity coupled to matter. It also
serves as a timely introduction by examples to the classical and quantum BV-BFV
formalism as well as to the AKSZ method.


title: Lower Bounds on Active Learning for Graphical Model Selection

abstract:
  We consider the problem of estimating the underlying graph associated with a
Markov random field, with the added twist that the decoding algorithm can
iteratively choose which subsets of nodes to sample based on the previous
samples, resulting in an active learning setting. Considering both Ising and
Gaussian models, we provide algorithm-independent lower bounds for
high-probability recovery within the class of degree-bounded graphs. Our main
results are minimax lower bounds for the active setting that match the best
known lower bounds for the passive setting, which in turn are known to be tight
in several cases of interest. Our analysis is based on Fano's inequality, along
with novel mutual information bounds for the active learning setting, and the
application of restricted graph ensembles. While we consider ensembles that are
similar or identical to those used in the passive setting, we require different
analysis techniques, with a key challenge being bounding a mutual information
quantity associated with observed subsets of nodes, as opposed to full
observations.


title:
Convergence to the boundary for random walks on discrete quantum groups
  and monoidal categories

abstract:
  We study the problem of convergence to the boundary in the setting of random
walks on discrete quantum groups. Convergence to the boundary is established
for random walks on $\hat{\textrm{SU}_q(2)}$. Furthermore, we will define the
Martin boundary for random walks on C$^*$-tensor categories and give a
formulation for convergence to the boundary for such random walks. These
categorical definitions are shown to be compatible with the definitions in the
quantum group case. This implies that convergence to the boundary for random
walks on quantum groups is stable under monoidal equivalence.


title: Power Monitoring and Control for Large Scale projects: SKA, a case study

abstract:
  Large sensor-based science infrastructures for radio astronomy like the SKA
will be among the most intensive data-driven projects in the world, facing very
high demanding computation, storage, management, and above all power demands.
The geographically wide distribution of the SKA and and its associated
processing requirements in the form of tailored High Performance Computing
(HPC) facilities, require a Greener approach towards the Information and
Communications Technologies (ICT) adopted for the data processing to enable
operational compliance to potentially strict power budgets. Addressing the
reduction of electricity costs, improve system power monitoring and the
generation and management of electricity at system level is paramount to avoid
future inefficiencies and higher costs and enable fulfillments of Key Science
Cases. Here we outline major characteristics and innovation approaches to
address power efficiency and long-term power sustainability for radio astronomy
projects, focusing on Green ICT for science and Smart power monitoring and
control.


title: Calabi--Yau quotients of hyperk\"ahler four-folds

abstract:
  The aim of this paper is to construct Calabi-Yau 4-folds as crepant
resolutions of the quotients of a hyperk\"ahler 4-fold $X$ by a non symplectic
involution $\alpha$. We first compute the Hodge numbers of a Calabi-Yau
constructed in this way in a general setting and then we apply the results to
several specific examples of non symplectic involutions, producing Calabi-Yau
4-folds with different Hodge diamonds. Then we restrict ourselves to the case
where $X$ is the Hilbert scheme of two points on a K3 surface $S$ and the
involution $\alpha$ is induced by a non symplectic involution on the K3
surface. In this case we compare the Calabi-Yau 4-fold $Y_S$, which is the
crepant resolution of $X/\alpha$, with the Calabi-Yau 4-fold $Z_S$, constructed
from $S$ through the Borcea--Voisin construction. We give several explicit
geometrical examples of both these Calabi--Yau 4-folds describing maps related
to interesting linear systems as well as a rational $2:1$ map from $Z_S$ to
$Y_S$.


title: Unbiased contaminant removal for 3D galaxy power spectrum measurements

abstract:
  We assess and develop techniques to remove contaminants when calculating the
3D galaxy power spectrum. We separate the process into three separate stages:
(i) removing the contaminant signal, (ii) estimating the uncontaminated
cosmological power spectrum, (iii) debiasing the resulting estimates. For (i),
we show that removing the best-fit contaminant mode subtraction), and setting
the contaminated components of the covariance to be infinite (mode
deprojection) are mathematically equivalent. For (ii), performing a Quadratic
Maximum Likelihood (QML) estimate after mode deprojection gives an optimal
unbiased solution, although it requires the manipulation of large $N_{\rm
mode}^2$ matrices ($N_{\rm mode}$ being the total number of modes)}, which is
unfeasible for recent 3D galaxy surveys. Measuring a binned average of the
modes for (ii) as proposed by \citet*[FKP]{Feldman} is faster and simpler, but
is sub-optimal and gives rise to a biased solution. We present a method to
debias the resulting FKP measurements that does not require any large matrix
calculations. We argue that the sub-optimality of the FKP estimator compared
with the QML estimator, caused by contaminants is less severe than that
commonly ignored due to the survey window.


title:
Homogenization of a Fully Coupled Thermoelasticity Problem for a Highly
  Heterogeneous Medium With a Priori Known Phase Transformations

abstract:
  We investigate a linear, fully coupled thermoelasticity problem for a highly
heterogeneous, two-phase medium. The medium in question consists of a connected
matrix with disconnected, initially periodically distributed inclusions
separated by a sharp interface undergoing an a priori known interface movement
due to phase transformations. After transforming the moving geometry to an
$\varepsilon$-periodic, fixed reference domain, we establish the well-posedness
of the model and derive a number of $\varepsilon$-independent a priori
estimates. Via a two-scale convergence argument, we then show that the
$\varepsilon$-dependent solutions converge to solutions of a corresponding
upscaled model with distributed time-dependent microstructures.


title:
Divisive-agglomerative algorithm and complexity of automatic
  classification problems

abstract:
  An algorithm of solution of the Automatic Classification (AC for brevity)
problem is set forth in the paper. In the AC problem, it is required to find
one or several artitions, starting with the given pattern matrix or
dissimilarity, similarity matrix.


title: Blockchain Mining Games

abstract:
  We study the strategic considerations of miners participating in the
bitcoin's protocol. We formulate and study the stochastic game that underlies
these strategic considerations. The miners collectively build a tree of blocks,
and they are paid when they create a node (mine a block) which will end up in
the path of the tree that is adopted by all. Since the miners can hide newly
mined nodes, they play a game with incomplete information. Here we consider two
simplified forms of this game in which the miners have complete information. In
the simplest game the miners release every mined block immediately, but are
strategic on which blocks to mine. In the second more complicated game, when a
block is mined it is announced immediately, but it may not be released so that
other miners cannot continue mining from it. A miner not only decides which
blocks to mine, but also when to release blocks to other miners. In both games,
we show that when the computational power of each miner is relatively small,
their best response matches the expected behavior of the bitcoin designer.
However, when the computational power of a miner is large, he deviates from the
expected behavior, and other Nash equilibria arise.


title:
Alternative versions of the global competitive industrial performance
  ranking constructed by methods from social choice theory

abstract:
  The Competitive Industrial Performance index (developed by experts of the
UNIDO) is designed as a measure of national competitiveness. Index is an
aggregate of eight observable variables, representing different dimensions of
competitive industrial performance.


title: Rating models: emerging market distinctions

abstract:
  The Basel II Accords have sparked increased interest in the development of
approaches based on internal ratings systems and have initiated the elaboration
of models for remote ratings forecasts based on external ones as part of Risk
Management and Early Warning Systems. This article evaluates the peculiarities
of current ratings systems and addresses specific issues of development of
econometrical rating models for emerging market companies.


title: Fair division with divisible and indivisible items

abstract:
  In the work the fair division problem for two participants in presence of
both divisible and indivisible items is considered. The set of all divisions is
formally described; it is demonstrated that fair (in terms of Brams and Taylor)
divisions, unlikely the case where all the items are divisible, not always
exist. The necessary and sufficient conditions of existence of proportional and
equitable division were found.


title:
Study of baryon acoustic oscillations with SDSS DR12 data and
  measurement of $\Omega_\textrm{DE}(a)$

abstract:
  We define Baryon Acoustic Oscillation (BAO) distances $\hat{d}_\alpha(z,
z_c)$, $\hat{d}_z(z, z_c)$, and $\hat{d}_/(z, z_c)$ that do not depend on
cosmological parameters. These BAO distances are measured as a function of
redshift $z$ with the Sloan Digital Sky Survey (SDSS) data release DR12. From
these BAO distances alone, or together with the correlation angle
$\theta_\textrm{MC}$ of the Cosmic Microwave Background (CMB), we constrain the
cosmological parameters in several scenarios. We find $4.3 \sigma$ tension
between the BAO plus $\theta_\textrm{MC}$ data and a cosmology with flat space
and constant dark energy density $\Omega_\textrm{DE}(a)$. Releasing one and/or
the other of these constraints obtains agreement with the data. We measure
$\Omega_\textrm{DE}(a)$ as a function of $a$.


title: Measuring Complexity in Cantor Dynamics

abstract:
  These notes from lectures by the author at the CIMPA Research School held in
Salta, Argentina, in November 2015 review definitions and properties of various
measures of complexity in topological and measure-preserving dynamical systems,
especially symbolic dynamical systems.


title:
Janus-Facedness of the Pion: Analytic Instantaneous Bethe-Salpeter
  Models

abstract:
  Inversion enables the construction of interaction potentials underlying -
under fortunate circumstances even analytic - instantaneous Bethe-Salpeter
descriptions of all lightest pseudoscalar mesons as quark-antiquark bound
states of Goldstone-boson nature.


title:
GPU Accelerated Discrete Element Method (DEM) Molecular Dynamics for
  Conservative, Faceted Particle Simulations

abstract:
  Faceted shapes, such as polyhedra, are commonly found in systems of
nanoscale, colloidal, and granular particles. Many interesting physical
phenomena, like crystal nucleation and growth, vacancy motion, and glassy
dynamics are challenging to model in these systems because they require
detailed dynamical information at the individual particle level. Within the
granular materials community the Discrete Element Method has been used
extensively to model systems of anisotropic particles under gravity, with
friction. We provide an implementation of this method intended for simulation
of hard, faceted nanoparticles, with a conservative Weeks-Chandler-Andersen
(WCA) interparticle potential, coupled to a thermodynamic ensemble. This method
is a natural extension of classical molecular dynamics and enables rigorous
thermodynamic calculations for faceted particles.


title: 0-$\pi$ phase-controllable $thermal$ Josephson junction

abstract:
  Two superconductors coupled by a weak link support an equilibrium Josephson
electrical current which depends on the phase difference $\varphi$ between the
superconducting condensates [1]. Yet, when a temperature gradient is imposed
across the junction, the Josephson effect manifests itself through a coherent
component of the heat current that flows oppositely to the thermal gradient for
$ \varphi <\pi/2$ [2-4]. The direction of both the Josephson charge and heat
currents can be inverted by adding a $\pi$ shift to $\varphi$. In the static
electrical case, this effect was obtained in a few systems, e.g. via a
ferromagnetic coupling [5,6] or a non-equilibrium distribution in the weak link
[7]. These structures opened new possibilities for superconducting quantum
logic [6,8] and ultralow power superconducting computers [9]. Here, we report
the first experimental realization of a thermal Josephson junction whose phase
bias can be controlled from $0$ to $\pi$. This is obtained thanks to a
superconducting quantum interferometer that allows to fully control the
direction of the coherent energy transfer through the junction [10]. This
possibility, joined to the completely superconducting nature of our system,
provides temperature modulations with unprecedented amplitude of $\sim$ 100 mK
and transfer coefficients exceeding 1 K per flux quantum at 25 mK. Then, this
quantum structure represents a fundamental step towards the realization of
caloritronic logic components, such as thermal transistors, switches and memory
devices [10,11]. These elements, combined with heat interferometers [3,4,12]
and diodes [13,14], would complete the thermal conversion of the most important
phase-coherent electronic devices and benefit cryogenic microcircuits requiring
energy management, such as quantum computing architectures and radiation
sensors.


title:
Free products in the unit group of the integral group ring of a finite
  group

abstract:
  Let $G$ be a finite group and let $p$ be a prime. We continue the search for
generic constructions of free products and free monoids in the unit group
$\mathcal{U}(\mathbb{Z}G)$ of the integral group ring $\mathbb{Z}G$. For a
nilpotent group $G$ with a non-central element $g$ of order $p$, explicit
generic constructions are given of two periodic units $b_1$ and $b_2$ in
$\mathcal{U}(\mathbb{Z}G)$ such that $\langle b_1 , b_2\rangle =\langle
b_1\rangle \star \langle b_2 \rangle \cong \mathbb{Z}_p \star \mathbb{Z}_{p}$,
a free product of two cyclic groups of prime order. Moreover, if $G$ is
nilpotent of class $2$ and $g$ has order $p^n$, then also concrete generators
for free products $\mathbb{Z}_{p^k} \star \mathbb{Z}_{p^m}$ are constructed
(with $1\leq k,m\leq n $). As an application, for finite nilpotent groups, we
obtain earlier results of Marciniak-Sehgal and Gon{\c{c}}alves-Passman.
Further, for an arbitrary finite group $G$ we give generic constructions of
free monoids in $\mathcal{U}(\mathbb{Z}G)$ that generate an infinite solvable
subgroup.


title: Explicit bounds for generators of the class group

abstract:
  Assuming Generalized Riemann's Hypothesis, Bach proved that the class group
$\mathcal C\!\ell_{\mathbf K}$ of a number field ${\mathbf K}$ may be generated
using prime ideals whose norm is bounded by $12\log^2\Delta_{\mathbf K}$, and
by $(4+o(1))\log^2\Delta_{\mathbf K}$ asymptotically, where $\Delta_{\mathbf
K}$ is the absolute value of the discriminant of ${\mathbf K}$. Under the same
assumption, Belabas, Diaz y Diaz and Friedman showed a way to determine a set
of prime ideals that generates $\mathcal C\!\ell_{\mathbf K}$ and which
performs better than Bach's bound in computations, but which is asymptotically
worse. In this paper we show that $\mathcal C\!\ell_{\mathbf K}$ is generated
by prime ideals whose norm is bounded by the minimum of
$4.01\log^2\Delta_{\mathbf K}$, $4\big(1+\big(2\pi e^{\gamma})^{-n_{\mathbf
K}}\big)^2\log^2\Delta_{\mathbf K}$ and $4\big(\log\Delta_{\mathbf
K}+\log\log\Delta_{\mathbf K}-(\gamma+\log 2\pi)n_{\mathbf K}+1+(n_{\mathbf
K}+1)\frac{\log(7\log\Delta_{\mathbf K})}{\log\Delta_{\mathbf K}}\big)^2$.
Moreover, we prove explicit upper bounds for the size of the set determined by
Belabas, Diaz y Diaz and Friedman's algorithms, confirming that it has size
$\asymp (\log\Delta_{\mathbf K}\log\log\Delta_{\mathbf K})^2$. In addition, we
propose a different algorithm which produces a set of generators which
satisfies the above mentioned bounds and in explicit computations turns out to
be experimentally smaller than $\log^2\Delta_{\mathbf K}$ except for 7 out of
31000 fields.


title:
Learning opening books in partially observable games: using random seeds
  in Phantom Go

abstract:
  Many artificial intelligences (AIs) are randomized. One can be lucky or
unlucky with the random seed; we quantify this effect and show that, maybe
contrarily to intuition, this is far from being negligible. Then, we apply two
different existing algorithms for selecting good seeds and good probability
distributions over seeds. This mainly leads to learning an opening book. We
apply this to Phantom Go, which, as all phantom games, is hard for opening book
learning. We improve the winning rate from 50% to 70% in 5x5 against the same
AI, and from approximately 0% to 40% in 5x5, 7x7 and 9x9 against a stronger
(learning) opponent.


title:
Redshift Measurement and Spectral Classification for eBOSS Galaxies with
  the Redmonster Software

abstract:
  We describe the redmonster automated redshift measurement and spectral
classification software designed for the extended Baryon Oscillation
Spectroscopic Survey (eBOSS) of the Sloan Digital Sky Survey IV (SDSS-IV). We
describe the algorithms, the template standard and requirements, and the newly
developed galaxy templates to be used on eBOSS spectra. We present results from
testing on early data from eBOSS, where we have found a 90.5% automated
redshift and spectral classification success rate for the luminous red galaxy
sample (redshifts 0.6$\lesssim z \lesssim$1.0). The redmonster performance
meets the eBOSS cosmology requirements for redshift classification and
catastrophic failures, and represents a significant improvement over the
previous pipeline. We describe the empirical processes used to determine the
optimum number of additive polynomial terms in our models and an acceptable
$\Delta\chi_r^2$ threshold for declaring statistical confidence. Statistical
errors on redshift measurement due to photon shot noise are assessed, and we
find typical values of a few tens of km s$^{-1}$. An investigation of redshift
differences in repeat observations scaled by error estimates yields a
distribution with a Gaussian mean and standard deviation of $\mu\sim$0.01 and
$\sigma\sim$0.65, respectively, suggesting the reported statistical redshift
uncertainties are over-estimated by $\sim$54%. We assess the effects of object
magnitude, signal-to-noise ratio, fiber number, and fiber head location on the
pipeline's redshift success rate. Finally, we describe directions of ongoing
development.


title: Plane-filling curves on all uniform grids

abstract:
  We describe a search for plane-filling curves traversing all edges of a grid
once. The curves are given by Lindenmayer systems with only one non-constant
letter. All such curves for small orders on three grids have been found. For
all uniform grids we show how curves traversing all points once can be obtained
from the curves found. Curves traversing all edges once are described for the
four uniform grids where they exist.


title: Stochastic Geometry Methods for Modelling Automotive Radar Interference

abstract:
  As the use of automotive radar increases, performance limitations associated
with radar-to-radar interference will become more significant. In this paper we
employ tools from stochastic geometry to characterize the statistics of radar
interference. Specifically, using two different models for vehicle spacial
distributions, namely, a Poisson point process and a Bernoulli lattice process,
we calculate for each case the interference statistics and obtain analytical
expressions for the probability of successful range estimation. Our study shows
that the regularity of the geometrical model appears to have limited effect on
the interference statistics, and so it is possible to obtain tractable tight
bounds for worst case performance. A technique is proposed for designing the
duty cycle for random spectrum access which optimizes the total performance.
This analytical framework is verified using Monte-Carlo simulations.


title: Optimal Rates of Statistical Seriation

abstract:
  Given a matrix the seriation problem consists in permuting its rows in such
way that all its columns have the same shape, for example, they are monotone
increasing. We propose a statistical approach to this problem where the matrix
of interest is observed with noise and study the corresponding minimax rate of
estimation of the matrices. Specifically, when the columns are either unimodal
or monotone, we show that the least squares estimator is optimal up to
logarithmic factors and adapts to matrices with a certain natural structure.
Finally, we propose a computationally efficient estimator in the monotonic case
and study its performance both theoretically and experimentally. Our work is at
the intersection of shape constrained estimation and recent work that involves
permutation learning, such as graph denoising and ranking.


title: Document Clustering Games in Static and Dynamic Scenarios

abstract:
  In this work we propose a game theoretic model for document clustering. Each
document to be clustered is represented as a player and each cluster as a
strategy. The players receive a reward interacting with other players that they
try to maximize choosing their best strategies. The geometry of the data is
modeled with a weighted graph that encodes the pairwise similarity among
documents, so that similar players are constrained to choose similar
strategies, updating their strategy preferences at each iteration of the games.
We used different approaches to find the prototypical elements of the clusters
and with this information we divided the players into two disjoint sets, one
collecting players with a definite strategy and the other one collecting
players that try to learn from others the correct strategy to play. The latter
set of players can be considered as new data points that have to be clustered
according to previous information. This representation is useful in scenarios
in which the data are streamed continuously. The evaluation of the system was
conducted on 13 document datasets using different settings. It shows that the
proposed method performs well compared to different document clustering
algorithms.


title: Robust Assignments via Ear Decompositions and Randomized Rounding

abstract:
  Many real-life planning problems require making a priori decisions before all
parameters of the problem have been revealed. An important special case of such
problem arises in scheduling problems, where a set of tasks needs to be
assigned to the available set of machines or personnel (resources), in a way
that all tasks have assigned resources, and no two tasks share the same
resource. In its nominal form, the resulting computational problem becomes the
\emph{assignment problem} on general bipartite graphs.
  This paper deals with a robust variant of the assignment problem modeling
situations where certain edges in the corresponding graph are \emph{vulnerable}
and may become unavailable after a solution has been chosen. The goal is to
choose a minimum-cost collection of edges such that if any vulnerable edge
becomes unavailable, the remaining part of the solution contains an assignment
of all tasks.
  We present approximation results and hardness proofs for this type of
problems, and establish several connections to well-known concepts from
matching theory, robust optimization and LP-based techniques.


title: Monoid-like definitions of cyclic operads

abstract:
  Guided by the microcosm principle of Baez-Dolan and by the algebraic
definitions of operads of Kelly and Fiore, we introduce two "monoid-like"
definitions of cyclic operads, one for the original, "exchangable-output"
characterisation of Getzler-Kapranov, and the other for the alternative
"entries-only" characterisation, both within the category of Joyal's species of
structures. Relying on a result of Lamarche on descent for species, we use
these "monoid-like" definitions to prove the equivalence between the
"exchangable-output" and "entries-only" points of view on cyclic operads.


title:
Addendum to "Super-GCA from $\mathcal{N}=(2,2)$ super-Virasoro":
  Super-GCA connection with tensionless strings

abstract:
  In this addendum, we consider the connection between certain $2d$ super-GCA,
obtained from the parametric contractions of $2d$ SCFTs, which can describe the
constraint algebra of null spinning strings.


title:
Linear spectropolarimetry across the optical spectrum of Herbig Ae/Be
  stars

abstract:
  We present the results of spectropolarimetric observations of 12 Herbig Ae/Be
objects. Our data have the largest spectropolarimetric wavelength coverage,
4560 {\AA} to 9480 {\AA}, published to date. A change in linear polarisation
across the H{\alpha} line, is detected in all objects. Such a line effect
reveals the fact that stellar photons are scattered off free electrons that are
not distributed in a spherically symmetric volume, suggesting the presence of
small disks around these accreting objects. Thanks to the large wavelength
coverage, we can report that H{\alpha} is the spectral line in the optical
wavelength range that is most sensitive to revealing deviations from spherical
symmetry, and the one most likely to show a line effect across the polarisation
in such cases. Few other spectral lines display changes in polarisation across
the line. In addition, H{\alpha} is the only line which shows an effect across
its absorption component in some sources. We present a scenario explaining this
finding and demonstrate that the detection of the line effect strongly relies
on the number of photons scattered into our line of sight. We highlight the
special case of R Mon, which is the only object in our sample to show many
lines with a polarisation effect, which is much stronger than in all other
objects. Given that the object and its nebulosity is spatially resolved, we
argue that this is due to scattering of the stellar and emission spectrum off
circumstellar dust.


title:
Generalized Hypergeometric Ensembles: Statistical Hypothesis Testing in
  Complex Networks

abstract:
  Statistical ensembles of networks, i.e., probability spaces of all networks
that are consistent with given aggregate statistics, have become instrumental
in the analysis of complex networks. Their numerical and analytical study
provides the foundation for the inference of topological patterns, the
definition of network-analytic measures, as well as for model selection and
statistical hypothesis testing. Contributing to the foundation of these data
analysis techniques, in this Letter we introduce generalized hypergeometric
ensembles, a broad class of analytically tractable statistical ensembles of
finite, directed and weighted networks. This framework can be interpreted as a
generalization of the classical configuration model, which is commonly used to
randomly generate networks with a given degree sequence or distribution. Our
generalization rests on the introduction of dyadic link propensities, which
capture the degree-corrected tendencies of pairs of nodes to form edges between
each other. Studying empirical and synthetic data, we show that our approach
provides broad perspectives for model selection and statistical hypothesis
testing in data on complex networks.

categories: physics.soc-ph cs.SI math.CO physics.data-an


title: The Tau of Galaxy Clusters

abstract:
  The recent emergence of detections of the kinetic Sunyaev-Zel'dovich (kSZ)
effect through cross-correlation techniques is encouraging for the prospects of
future cosmic microwave background (CMB) experiments. Extracting information on
the large-scale velocity fields and constraining cosmological parameters from
such kSZ measurements requires an understanding of the optical depth to CMB
photons through halos. Using cosmological hydrodynamic simulations we find that
there exists a low-scatter relation between the optical depth and thermal
Sunyaev-Zel'dovich (tSZ) signal of halos within a physical aperture. We propose
that such a relation can be used to break the degeneracy between optical depth
and line-of-sight velocity in kSZ measurements. The limiting factors in our
proposal are systematic uncertainties associated with the sub-grid physics
models in the simulations, which we calculate to be less than 10 percent. We
discuss future observational measurements that could potentially be used to
mitigate the systematic uncertainties in this scaling relation.


title:
TARGET 5: a new multi-channel digitizer with triggering capabilities for
  gamma-ray atmospheric Cherenkov telescopes

abstract:
  TARGET~5 is a new application-specific integrated circuit (ASIC) of the
TARGET family, designed for the readout of signals from photosensors in the
cameras of imaging atmospheric Cherenkov telescopes (IACTs) for ground-based
gamma-ray astronomy. TARGET~5 combines sampling and digitization on 16 signal
channels with the formation of trigger signals based on the analog sum of
groups of four channels. We describe the ASIC architecture and performance.
TARGET~5 improves over the performance of the first-generation TARGET ASIC,
achieving: tunable sampling frequency from $<0.4$~GSa/s to $>1$~GSa/s; a
dynamic range on the data path of 1.2 V with effective dynamic range of 11~bits
and DC noise of ${\sim}0.6$~mV; 3-dB bandwidth of 500 MHz; crosstalk between
adjacent channels $<1.3\%$; charge resolution improving from 40\% to $<4\%$
between 3 photoelectrons (p.e.) and $>100$~p.e. (assuming 4 mV per p.e.); and
minimum stable trigger threshold of 20 mV (5 p.e.) with trigger noise of 5 mV
(1.2 p.e.), which is mostly limited by interference between trigger and
sampling operations. TARGET~5 is the first ASIC of the TARGET family used in an
IACT prototype, providing one development path for readout electronics in the
forthcoming Cherenkov Telescope Array (CTA).


title: Explaining Deep Convolutional Neural Networks on Music Classification

abstract:
  Deep convolutional neural networks (CNNs) have been actively adopted in the
field of music information retrieval, e.g. genre classification, mood
detection, and chord recognition. However, the process of learning and
prediction is little understood, particularly when it is applied to
spectrograms. We introduce auralisation of a CNN to understand its underlying
mechanism, which is based on a deconvolution procedure introduced in [2].
Auralisation of a CNN is converting the learned convolutional features that are
obtained from deconvolution into audio signals. In the experiments and
discussions, we explain trained features of a 5-layer CNN based on the
deconvolved spectrograms and auralised signals. The pairwise correlations per
layers with varying different musical attributes are also investigated to
understand the evolution of the learnt features. It is shown that in the deep
layers, the features are learnt to capture textures, the patterns of continuous
distributions, rather than shapes of lines.


title:
Assessing Compatibility of Direct Detection Data: Halo-Independent
  Global Likelihood Analyses

abstract:
  We present two different halo-independent methods to assess the compatibility
of several direct dark matter detection data sets for a given dark matter model
using a global likelihood consisting of at least one extended likelihood and an
arbitrary number of Gaussian or Poisson likelihoods. In the first method we
find the global best fit halo function (we prove that it is a unique piecewise
constant function with a number of down steps smaller than or equal to a
maximum number that we compute) and construct a two-sided pointwise confidence
band at any desired confidence level, which can then be compared with those
derived from the extended likelihood alone to assess the joint compatibility of
the data. In the second method we define a "constrained parameter
goodness-of-fit" test statistic, whose $p$-value we then use to define a
"plausibility region" (e.g. where $p \geq 10\%$). For any halo function not
entirely contained within the plausibility region, the level of compatibility
of the data is very low (e.g. $p < 10 \%$). We illustrate these methods by
applying them to CDMS-II-Si and SuperCDMS data, assuming dark matter particles
with elastic spin-independent isospin-conserving interactions or exothermic
spin-independent isospin-violating interactions.


title: Stable foliations near a traveling front for reaction diffusion systems

abstract:
  We establish the existence of a stable foliation in the vicinity of a
traveling front solution for systems of reaction diffusion equations in one
space dimension that arise in the study of chemical reactions models and solid
fuel combustion. In this way we complement the orbital stability results from
earlier papers by A. Ghazaryan, S. Schecter and Y. Latushkin. The essential
spectrum of the differential operator obtained by linearization at the front
touches the imaginary axis. In spaces with exponential weights, one can shift
the spectrum to the left. We study the nonlinear equation on the intersection
of the unweighted and weighted spaces. Small translations of the front form a
center unstable manifold. For each small translation we prove the existence of
a stable manifold containing the translated front and show that the stable
manifolds foliate a small ball centered at the front.


title: A Weighted Exact Test for Mutually Exclusive Mutations in Cancer

abstract:
  The somatic mutations in the pathways that drive cancer development tend to
be mutually exclusive across tumors, providing a signal for distinguishing
driver mutations from a larger number of random passenger mutations. This
mutual exclusivity signal can be confounded by high and highly variable
mutation rates across a cohort of samples. Current statistical tests for
exclusivity that incorporate both per-gene and per-sample mutational
frequencies are computationally expensive and have limited precision.
  We formulate a weighted exact test for assessing the significance of
mutational exclusivity in an arbitrary number of mutational events. Our test
conditions on the number of samples with a mutation as well as per-event,
per-sample mutation probabilities. We provide a recursive formula to compute
$p$-values for the weighted test exactly as well as a highly accurate and
efficient saddlepoint approximation of the test. We use our test to approximate
a commonly used permutation test for exclusivity that conditions on per-event,
per-sample mutation frequencies. However, our test is more efficient and it
recovers more significant results than the permutation test. We use our
Weighted Exclusivity Test (WExT) software to analyze hundreds of colorectal and
endometrial samples from The Cancer Genome Atlas, which are two cancer types
that often have extremely high mutation rates. On both cancer types, the
weighted test identifies sets of mutually exclusive mutations in cancer genes
with fewer false positives than earlier approaches.


title: Doubly assisted Sauter-Schwinger effect

abstract:
  We study electron-positron pair creation by a strong and slowly varying
electric field, assisted by a weaker and more rapidly changing field (e.g., in
the keV regime) plus an additional high-energy (say MeV) photon. It turns out
that this combination can yield a pair creation probability which is
exponentially larger than in the case where one (or more) of the three
ingredients is missing. Apart from a deeper understanding of these
non-perturbative phenomena, this double enhancement may pave the way for an
experimental verification of this fundamental prediction.


title:
High Tc superconductivity at the interface between the CaCuO2 and SrTiO3
  insulating oxides

abstract:
  At interfaces between complex oxides it is possible to generate electronic
systems with unusual electronic properties, which are not present in the
isolated oxides. One important example is the appearance of superconductivity
at the interface between insulating oxides, although, until now, with very low
Tc. We report the occurrence of high Tc superconductivity in the bilayer
CaCuO2/SrTiO3, where both the constituent oxides are insulating. In order to
obtain a superconducting state, the CaCuO2/SrTiO3 interface must be realized
between the Ca plane of CaCuO2 and the TiO2 plane of SrTiO3. Only in this case
extra oxygen ions can be incorporated in the interface Ca plane, acting as
apical oxygen for Cu and providing holes to the CuO2 planes. A detailed hole
doping spatial profile has been obtained by STEM/EELS at the O K-edge, clearly
showing that the (super)conductivity is confined to about 1-2 CaCuO2 unit cells
close to the interface with SrTiO3. The results obtained for the CaCuO2/SrTiO3
interface can be extended to multilayered high Tc cuprates, contributing to
explain the dependence of Tc on the number of CuO2 planes in these systems.


title:
Proceedings of the 2016 ICML Workshop on #Data4Good: Machine Learning in
  Social Good Applications

abstract:
  This is the Proceedings of the ICML Workshop on #Data4Good: Machine Learning
in Social Good Applications, which was held on June 24, 2016 in New York.


title: Elastic deformations driven by non-uniform lubrication flows

abstract:
  The ability to create dynamic deformations of micron-sized structures is
relevant to a wide variety of applications such as adaptable optics, soft
robotics, and reconfigurable microfluidic devices. In this work we examine
non-uniform lubrication flow as a mechanism to create complex deformation
fields in an elastic plate. We consider a Kirchoff-Love elasticity model for
the plate and Hele-Shaw flow in a narrow gap between the plate and a parallel
rigid surface. Based on linearization of the Reynolds equation, we obtain a
governing equation which relates elastic deformations to gradients in
non-homogenous physical properties of the fluid (e.g. body forces, viscosity,
and slip velocity). We then focus on a specific case of non-uniform
Helmholtz-Smoluchowski electroosmotic slip velocity, and provide a method for
determining the zeta-potential distribution necessary to generate arbitrary
static and quasi-static deformations of the elastic plate. Extending the
problem to time-dependent solutions, we analyze transient effects on
asymptotically static solutions, and finally provide a closed form solution for
a Green's function for time periodic actuations.


title:
Constructing bibliometric networks: A comparison between full and
  fractional counting

abstract:
  The analysis of bibliometric networks, such as co-authorship, bibliographic
coupling, and co-citation networks, has received a considerable amount of
attention. Much less attention has been paid to the construction of these
networks. We point out that different approaches can be taken to construct a
bibliometric network. Normally the full counting approach is used, but we
propose an alternative fractional counting approach. The basic idea of the
fractional counting approach is that each action, such as co-authoring or
citing a publication, should have equal weight, regardless of for instance the
number of authors, citations, or references of a publication. We present two
empirical analyses in which the full and fractional counting approaches yield
very different results. These analyses deal with co-authorship networks of
universities and bibliographic coupling networks of journals. Based on
theoretical considerations and on the empirical analyses, we conclude that for
many purposes the fractional counting approach is preferable over the full
counting one.


title:
Evaluating Random Mutant Selection at Class-Level in Projects with
  Non-Adequate Test Suites

abstract:
  Mutation testing is a standard technique to evaluate the quality of a test
suite. Due to its computationally intensive nature, many approaches have been
proposed to make this technique feasible in real case scenarios. Among these
approaches, uniform random mutant selection has been demonstrated to be simple
and promising. However, works on this area analyze mutant samples at project
level mainly on projects with adequate test suites. In this paper, we fill this
lack of empirical validation by analyzing random mutant selection at class
level on projects with non-adequate test suites. First, we show that uniform
random mutant selection underachieves the expected results. Then, we propose a
new approach named weighted random mutant selection which generates more
representative mutant samples. Finally, we show that representative mutant
samples are larger for projects with high test adequacy.


title: Spectral transitions for Aharonov-Bohm Laplacians on conical layers

abstract:
  We consider the Laplace operator in a tubular neighbourhood of a conical
surface of revolution, subject to an Aharonov-Bohm magnetic field supported on
the axis of symmetry and Dirichlet boundary conditions on the boundary of the
domain. We show that there exists a critical total magnetic flux depending on
the aperture of the conical surface for which the system undergoes an abrupt
spectral transition from infinitely many eigenvalues below the essential
spectrum to an empty discrete spectrum. For the critical flux we establish a
Hardy-type inequality. In the regime with infinite discrete spectrum we obtain
sharp spectral asymptotics with refined estimate of the remainder and
investigate the dependence of the eigenvalues on the aperture of the surface
and the flux of the magnetic field.

categories: math.SP math-ph math.AP math.MP quant-ph


title: Voronoi means, moving averages, and power series

abstract:
  We introduce a {\it non-regular} generalisation of the N\"{o}rlund mean, and
show its equivalence with a certain moving average. The Abelian and Tauberian
theorems establish relations with convergent sequences and certain power
series. A strong law of large numbers is also proved.


title: The $(b, c)$-inverse in rings and in the Banach context

abstract:
  In this article the $(b, c)$-inverse will be studied. Several equivalent
conditions for the existence of the $(b,c)$-inverse in rings will be given. In
particular, the conditions ensuring the existence of the $(b,c)$-inverse, of
the annihilator $(b,c)$-inverse and of the hybrid $(b,c)$-inverse will be
proved to be equivalent, provided $b$ and $c$ are regular elements in a unitary
ring $R$. In addition, the set of all $(b,c)$-invertible elements will be
characterized and the reverse order law will be also studied. Moreover, the
relationship between the $(b,c)$-inverse and the Bott-Duffin inverse will be
considered. In the context of Banach algebras, integral, series and limit
representations will be given. Finally the continuity of the $(b,c)$-inverse
will be characterized


title:
The two-dimensional O(3) model at nonzero density: from dual lattice
  simulations to repulsive bosons

abstract:
  We discuss the thermodynamics of the O(3) nonlinear sigma model in 1+1
dimensions at nonzero chemical potential (equivalent to a magnetic field). In
its conventional field theory representation the model suffers from a sign
problem. By dualizing the lattice model we present, for the first time, nonzero
density data of an asymptotically free theory with dynamical mass-gap. We find
a quantum phase transition at zero temperature where as a function of the
chemical potential the density assumes a nonzero value. We present evidence for
a corresponding dynamical critical exponent z close to 2. The low energy O(3)
model is conjectured to be described by a massive boson triplet with repulsive
interactions. We confirm the universal square root behavior expected for such a
system at low density (and temperature) and compare our data to the results of
Bethe ansatz solutions of the relativistic and non-relativistic one-dimensional
Bose gas. We also comment on a potential Berezinskii-Kosterlitz-Thouless
transition at nonzero density.


title: Erasure without work in an asymmetric, double-well potential

abstract:
  According to Landauer's principle, erasing a memory requires an average work
of at least $kT\ln2$ per bit. Recent experiments have confirmed this prediction
for a one-bit memory represented by a symmetric double-well potential. Here, we
present an experimental study of erasure for a memory encoded in an asymmetric
double-well potential. Using a feedback trap, we find that the average work to
erase can be less than $kT\ln2$. Surprisingly, erasure protocols that differ
subtly give measurably different values for the asymptotic work, a result we
explain by showing that one protocol is symmetric with the respect to time
reversal, while the other is not. The differences between the protocols help
clarify the distinctions between thermodynamic and logical reversibility.


title: Why We Refactor? Confessions of GitHub Contributors

abstract:
  Refactoring is a widespread practice that helps developers to improve the
maintainability and readability of their code. However, there is a limited
number of studies empirically investigating the actual motivations behind
specific refactoring operations applied by developers. To fill this gap, we
monitored Java projects hosted on GitHub to detect recently applied
refactorings, and asked the developers to ex- plain the reasons behind their
decision to refactor the code. By applying thematic analysis on the collected
responses, we compiled a catalogue of 44 distinct motivations for 12 well-known
refactoring types. We found that refactoring activity is mainly driven by
changes in the requirements and much less by code smells. Extract Method is the
most versatile refactoring operation serving 11 different purposes. Finally, we
found evidence that the IDE used by the developers affects the adoption of
automated refactoring tools.


title: Through the Big Bang

abstract:
  All measurements are comparisons. The only physically accessible degrees of
freedom (DOFs) are dimensionless ratios. The objective description of the
universe as a whole thus predicts only how these ratios change collectively as
one of them is changed. Here we develop a description for classical Bianchi IX
cosmology implementing these relational principles. The objective evolution
decouples from the volume and its expansion degree of freedom. We use the
relational description to investigate both vacuum dominated and quiescent
Bianchi IX cosmologies. In the vacuum dominated case the relational dynamical
system predicts an infinite amount of change of the relational DOFs, in
accordance with the well known chaotic behaviour of Bianchi IX. In the
quiescent case the relational dynamical system evolves uniquely though the
point where the decoupled scale DOFs predict the big bang/crunch. This is a
non-trivial prediction of the relational description; the big bang/crunch is
not the end of physics - it is instead a regular point of the relational
evolution. Describing our solutions as spacetimes that satisfy Einstein's
equations, we find that the relational dynamical system predicts two singular
solutions of GR that are connected at the hypersurface of the singularity such
that relational DOFs are continuous and the orientation of the spatial frame is
inverted.


title: On asymptotic behavior of the modified Arratia flow

abstract:
  We study asymptotic properties of the system of interacting diffusion
particles on the real line which transfer a mass [arXiv:1408.0628]. The system
is a natural generalization of the coalescing Brownian motions. The main
difference is that diffusion particles coalesce summing their mass and changing
their diffusion rate inversely proportional to the mass. First we construct the
system in the case where the initial mass distribution has the moment of the
order greater then two as an $L_2$-valued martingale with a suitable quadratic
variation. Then we find the relationship between the asymptotic behavior of the
particles and local properties of the mass distribution at the initial time.


title:
Morphology effects on spin-dependent transport and recombination in
  polyfluorene thin films

abstract:
  We have studied the role of spin-dependent processes on conductivity in
polyfluorene (PFO) thin films by conducting continuous wave (c.w.) electrically
detected magnetic resonance (EDMR) spectroscopy at temperatures between 10 K
and 293 K using microwave frequencies between about 100 MHz and 20 GHz as well
as pulsed EDMR at X-band. Variable frequency EDMR allows us to establish the
role of spin-orbit coupling in spin-dependent processes, pulsed EDMR probes
coherent spin motion effects. We used PFO for this study in order to allow for
the investigation of the effects of microscopic morphological ordering since
this material can adopt two distinct intrachain morphologies: an amorphous
(glassy) phase, and an ordered (beta) phase. In thin films of organic
light-emitting diodes (OLEDs) the appearance of a particular phase can be
controlled by deposition parameters, and is verified by electroluminescence
spectroscopy. We conducted multi-frequency c.w. EDMR, electrically detected
Rabi spinbeat experiments, Hahn-echo and inversion-recovery measurements.
Coherent echo spectroscopy reveals electrically detected electron spin-echo
envelope modulation (ESEEM) due to the precession of the carrier spins around
the protons. Our results demonstrate that while conformational disorder can
influence the observed EDMR signals, including the sign of the current changes
on resonance as well as the magnitudes of local hyperfine fields and charge
carrier spin-orbit interactions, it does not qualitatively affect the nature of
spin-dependent transitions in this material. At 293 K and 10 K, polaron-pair
recombination through weakly spin-spin coupled intermediate charge carrier pair
states is dominant, while at low temperatures, additional signatures of
spin-dependent charge transport through the interaction of polarons with
triplet excitons are seen in the half-field resonance of a triplet spin-1
species.


title:
A projection-based time-splitting algorithm for approximating nematic
  liquid crystal flows with stretching

abstract:
  A numerical method is developed for solving a system of partial differential
equations modeling the flow of a nematic liquid crystal fluid with stretching
effect, which takes into account the geometrical shape of its molecules. This
system couples the velocity vector, the scalar pressure and the director vector
representing the direction along which the molecules are oriented. The scheme
is designed by using finite elements in space and a time-splitting algorithm to
uncouple the calculation of the variables: the velocity and pressure are
computed by using a projection-based algorithm and the director is computed
jointly to an auxiliary variable. Moreover, the computation of this auxiliary
variable can be avoided at the discrete level by using piecewise constant
finite elements in its approximation. Finally, we use a pressure stabilization
technique allowing a stable equal-order interpolation for the velocity and the
pressure. Numerical experiments concerning annihilation of singularities are
presented to show the stability and efficiency of the scheme.


title:
A Classification Theorem for Varieties Generated by Wreath Products of
  Groups

abstract:
  We suggest a criterion under which for a nilpotent group of finite exponent
$A$ and for an abelian group $B$ the variety $var(A \,Wr\, B)$ generated by
their wreath product $A \,Wr\, B$ is equal to the product of varieties $var(A)$
and $var(B)$ generated by $A$ and $B$. Namely the equality holds if and only if
either the group $B$ is not of some non-zero exponent; or if $B$ is of a
non-zero exponent $n$, and $B$ contains a subgroup isomorphic to $C_{d}^c
\times C_{n/d}^\infty$, where $c$ is the nilpotency class of $A$, $d$ is the
largest divisor of $n$ coprime with $m$, $C_{d}^c$ is the direct power of $c$
copies of the cycle $C_d$ of order $d$, $C_{n/d}^\infty$ is the direct power of
countably many copies of the cycle $C_{n/d}$ of order $n/d$. This criterion
continues our previous work on cases when the similar criterions were given for
wreath products of abelian groups or of finite groups. Also, this is a
generalization of known results in literature, which solve the same problem for
much more restricted cases. Some applications of the criterion are considered
at the end of paper.


title:
Finite-size scaling of the Shannon-R\'enyi entropy in two-dimensional
  systems with spontaneously broken continuous symmetry

abstract:
  We study the scaling of the (basis dependent) Shannon entropy for
two-dimensional quantum antiferromagnets with N\'eel long-range order. We use a
massless free-field description of the gapless spin wave modes and phase space
arguments to treat the fact that the finite-size ground state is rotationally
symmetric, while there are degenerate physical ground states which break the
symmetry. Our results show that the Shannon entropy (and its R\'enyi
generalizations) possesses some universal logarithmic term proportional to the
number $N_\text{NG}$ of Nambu-Goldstone modes. In the case of a torus, we show
that $S_{n>1} \simeq {\rm const.} N+ \frac{N_\text{NG}}{4}\frac{n}{n-1} \ln{N}$
and $S_1 \simeq {\rm const.} N - \frac{N_\text{NG}}{4} \ln{N}$, where $N$ is
the total number of sites and $n$ the R\'enyi index. The result for $n>1$ is in
reasonable agreement with the quantum Monte Carlo results of Luitz et al.
[Phys. Rev. Lett. 112, 057203 (2014)], and qualitatively similar to those
obtained previously for the entanglement entropy. The Shannon entropy of a line
subsystem (embedded in the two-dimensional system) is also considered. Finally,
we present some density-matrix renormalization group (DMRG) calculations for a
spin$\frac{1}{2}$ XY model on the square lattice in a cylinder geometry. These
numerical data confirm our findings for logarithmic terms in the $n=\infty$
R\'enyi entropy (also called $-\ln{p_{\rm max}}$). They also reveal some
universal dependence on the cylinder aspect ratio, in good agreement with the
fact that, in that case, $p_{\rm max}$ is related to a non-compact free-boson
partition function in dimension 1+1.


title:
Solving finite-domain linear constraints in presence of the
  $\texttt{alldifferent}$

abstract:
  In this paper, we investigate the possibility of improvement of the
widely-used filtering algorithm for the linear constraints in constraint
satisfaction problems in the presence of the alldifferent constraints. In many
cases, the fact that the variables in a linear constraint are also constrained
by some alldifferent constraints may help us to calculate stronger bounds of
the variables, leading to a stronger constraint propagation. We propose an
improved filtering algorithm that targets such cases. We provide a detailed
description of the proposed algorithm and prove its correctness. We evaluate
the approach on five different problems that involve combinations of the linear
and the alldifferent constraints. We also compare our algorithm to other
relevant approaches. The experimental results show a great potential of the
proposed improvement.


title:
Log-Linear RNNs: Towards Recurrent Neural Networks with Flexible Prior
  Knowledge

abstract:
  We introduce LL-RNNs (Log-Linear RNNs), an extension of Recurrent Neural
Networks that replaces the softmax output layer by a log-linear output layer,
of which the softmax is a special case. This conceptually simple move has two
main advantages. First, it allows the learner to combat training data sparsity
by allowing it to model words (or more generally, output symbols) as complex
combinations of attributes without requiring that each combination is directly
observed in the training data (as the softmax does). Second, it permits the
inclusion of flexible prior knowledge in the form of a priori specified modular
features, where the neural network component learns to dynamically control the
weights of a log-linear distribution exploiting these features.
  We conduct experiments in the domain of language modelling of French, that
exploit morphological prior knowledge and show an important decrease in
perplexity relative to a baseline RNN.
  We provide other motivating iillustrations, and finally argue that the
log-linear and the neural-network components contribute complementary strengths
to the LL-RNN: the LL aspect allows the model to incorporate rich prior
knowledge, while the NN aspect, according to the "representation learning"
paradigm, allows the model to discover novel combination of characteristics.


title:
Infinitely many solutions for the Dirichlet problem involving the
  p-Laplacian in annulus

abstract:
  We present a result of existence of infinitely many solutions for the
Dirichlet problem involving the p-Laplacian in annular domains, when $p\leq N$,
contouring the failure of compactness of $W^{1,p}(\Omega)$ in
$C^0(\bar{\Omega})$ applying a variable change.


title:
Modelling Inflation with a Power-law Approach to the Inflationary
  Plateau

abstract:
  A new family of inflationary models is introduced and analysed. The behaviour
of the parameters characterising the models suggest preferred values, which
generate the most interesting testable predictions. Results are further
improved if late reheating and/or a subsequent period of thermal inflation is
taken into account. Specific model realisations consider a sub-Planckian
inflaton variation or a potential without fine-tuning of mass scales, based on
the Planck and grand unified theory scales. A toy model realisation in the
context of global and local supersymmetry is examined and results fitting the
Planck observations are determined.


title: Deep Learning for Mortgage Risk

abstract:
  We develop a deep learning model of multi-period mortgage risk and use it to
analyze an unprecedented dataset of origination and monthly performance records
for over 120 million mortgages originated across the US between 1995 and 2014.
Our estimators of term structures of conditional probabilities of prepayment,
foreclosure and various states of delinquency incorporate the dynamics of a
large number of loan-specific as well as macroeconomic variables down to the
zip-code level. The estimators uncover the highly nonlinear nature of the
relationship between the variables and borrower behavior, especially
prepayment. They also highlight the effects of local economic conditions on
borrower behavior. State unemployment has the greatest explanatory power among
all variables, offering strong evidence of the tight connection between housing
finance markets and the macroeconomy. The sensitivity of a borrower to changes
in unemployment strongly depends upon current unemployment. It also
significantly varies across the entire borrower population, which highlights
the interaction of unemployment and many other variables. These findings have
important implications for mortgage-backed security investors, rating agencies,
and housing finance policymakers.


title:
Multiple quantum phase transitions and superconductivity in Ce-based
  heavy fermions

abstract:
  Heavy fermions have served as prototype examples of strongly-correlated
electron systems. The occurrence of unconventional superconductivity in close
proximity to the electronic instabilities associated with various degrees of
freedom points to an intricate relationship between superconductivity and other
electronic states, which is unique but also shares some common features with
high temperature superconductivity. The magnetic order in heavy fermion
compounds can be continuously suppressed by tuning external parameters to a
quantum critical point, and the role of quantum criticality in determining the
properties of heavy fermion systems is an important unresolved issue. Here we
review the recent progress of studies on Ce based heavy fermion
superconductors, with an emphasis on the superconductivity emerging on the edge
of magnetic and charge instabilities as well as the quantum phase transitions
which occur by tuning different parameters, such as pressure, magnetic field
and doping. We discuss systems where multiple quantum critical points occur and
whether they can be classified in a unified manner, in particular in terms of
the evolution of the Fermi surface topology.