title:
Quantum epistemology from subquantum ontology: quantum mechanics from
  theory of classical random fields

abstract:
  The scientific methodology based on two descriptive levels, ontic (reality as
it is ) and epistemic (observational), is briefly presented. Following
Schr\"odinger, we point to the possible gap between these two descriptions. Our
main aim is to show that, although ontic entities may be inaccessible for
observations, they can be useful for clarification of the physical nature of
operational epistemic entities. We illustrate this thesis by the concrete
example: starting with the concrete ontic model preceding quantum mechanics
(the latter is treated as an epistemic model), namely, prequantum classical
statistical field theory (PCSFT), we propose the natural physical
interpretation for the basic quantum mechanical entity - the quantum state
("wave function"). The correspondence PCSFT to QM is not straightforward, it
couples the covariance operators of classical (prequantum) random fields with
the quantum density operators. We use this correspondence to clarify the
physical meaning of the pure quantum state and the superposition principle - by
using the formalism of classical field correlations.


title: Dynamical Decoupling and Homogenization of continuous variable systems

abstract:
  For finite-dimensional quantum systems, such as qubits, a well established
strategy to protect such systems from decoherence is dynamical decoupling.
However many promising quantum devices, such as oscillators, are infinite
dimensional, for which the question if dynamical decoupling could be applied
remained open. Here we first show that not every infinite-dimensional system
can be protected from decoherence through dynamical decoupling. Then we develop
dynamical decoupling for continuous variable systems which are described by
quadratic Hamiltonians. We identify a condition and a set of operations that
allow us to map a set of interacting harmonic oscillators onto a set of
non-interacting oscillators rotating with an averaged frequency, a procedure we
call homogenization. Furthermore we show that every quadratic
system-environment interaction can be suppressed with two simple operations
acting only on the system. Using a random dynamical decoupling or
homogenization scheme, we develop bounds that characterize how fast we have to
work in order to achieve the desired uncoupled dynamics. This allows us to
identify how well homogenization can be achieved and decoherence can be
suppressed in continuous variable systems.


title:
Neutrino-4 experiment on search for sterile neutrino with multi-section
  model of detector

abstract:
  In order to carry out research in the field of possible existence of sterile
neutrino the laboratory based on SM-3 reactor (Dimitrovgrad, Russia) was
created to search for oscillations of reactor antineutrino. The prototype of a
multi-section neutrino detector with liquid scintillator volume of 350 l was
installed in the middle of 2015. It is a moveable inside the passive shielding
detector, which can be set at distance range from 6 to 11 meters from the
reactor core. Measurements of antineutrino flux at such small distances from
the reactor core carried out with movable detector for the first time. The
measurements carried out with detector prototype demonstrated a possibility of
measuring a reactor antineutrino flux in difficult conditions of cosmic
background at Earth surface.


title:
A Frequency Domain Test for Propriety of Complex-Valued Vector Time
  Series

abstract:
  This paper proposes a frequency domain approach to test the hypothesis that a
complex-valued vector time series is proper, i.e., for testing whether the
vector time series is uncorrelated with its complex conjugate. If the
hypothesis is rejected, frequency bands causing the rejection will be
identified and might usefully be related to known properties of the physical
processes. The test needs the associated spectral matrix which can be estimated
by multitaper methods using, say, $K$ tapers. Standard asymptotic distributions
for the test statistic are of no use since they would require $K \rightarrow
\infty,$ but, as $K$ increases so does resolution bandwidth which causes
spectral blurring. In many analyses $K$ is necessarily kept small, and hence
our efforts are directed at practical and accurate methodology for hypothesis
testing for small $K.$ Our generalized likelihood ratio statistic combined with
exact cumulant matching gives very accurate rejection percentages and
outperforms other methods. We also prove that the statistic on which the test
is based is comprised of canonical coherencies arising from our complex-valued
vector time series.Our methodology is demonstrated on ocean current data
collected at different depths in the Labrador Sea. Overall this work extends
results on propriety testing for complex-valued vectors to the complex-valued
vector time series setting.


title: A particle-like description of Planckian black holes

abstract:
  In this paper we abandon the idea that even a "quantum" black hole, of Planck
size, can still be described as a classical, more or less complicated,
geometry. Rather, we consider a genuine quantum mechanical approach where a
Planckian black hole is, by all means, just another "particle", even if with a
distinguishing property: its linear size increases with the energy. The horizon
dynamics is equivalently described in terms of a particle moving in
gravitational potential derived from the horizon equation itself in a
self-consistent manner. The particle turning-points match the radius of the
inner and outer horizons of a charged black hole. This classical model pave the
way towards the wave equation for a truly quantum black hole. We compute the
exact form of the wave function and determine the energy spectrum. Finally, we
describe the classical limit in which the quantum picture correctly approaches
the classical geometric formulation. We find that the quantum-to-classical
transition occurs far above the Planck scale.


title:
Tongue contour extraction from ultrasound images based on deep neural
  network

abstract:
  Studying tongue motion during speech using ultrasound is a standard
procedure, but automatic ultrasound image labelling remains a challenge, as
standard tongue shape extraction methods typically require human intervention.
This article presents a method based on deep neural networks to automatically
extract tongue contour from ultrasound images on a speech dataset. We use a
deep autoencoder trained to learn the relationship between an image and its
related contour, so that the model is able to automatically reconstruct
contours from the ultrasound image alone. In this paper, we use an automatic
labelling algorithm instead of time-consuming hand-labelling during the
training process, and estimate the performances of both automatic labelling and
contour extraction as compared to hand-labelling. Observed results show quality
scores comparable to the state of the art.


title: Manifolds with analytic corners

abstract:
  Manifolds with boundary and with corners form categories ${\bf
Man}\subset{\bf Man^b}\subset{\bf Man^c}$. A manifold with corners $X$ has two
notions of tangent bundle: the tangent bundle $TX$, and the b-tangent bundle
${}^bTX$. The usual definition of smooth structure uses $TX$, as
$f:X\to\mathbb{R}$ is defined to be smooth if $\nabla^kf$ exists as a
continuous section of $\bigotimes^kT^*X$ for all $k\ge 0$.
  We define 'manifolds with analytic corners', or 'manifolds with a-corners',
with a different smooth structure, in which roughly $f:X\to\mathbb{R}$ is
smooth if ${}^b\nabla^kf$ exists as a continuous section of
$\bigotimes^k({}^bT^*X)$ for all $k\ge 0$. These are different from manifolds
with corners even when $X=[0,\infty)$, for instance
$x^\alpha:[0,\infty)\to\mathbb{R}$ is smooth for all real $\alpha\ge 0$ when
$[0,\infty)$ has a-corners. Manifolds with a-boundary and with a-corners form
categories ${\bf Man}\subset{\bf Man^{ab}}\subset{\bf Man^{ac}}$, with well
behaved differential geometry.
  Partial differential equations on manifolds with boundary may have boundary
conditions of two kinds: (i) 'at finite distance', e.g. Dirichlet or Neumann
boundary conditions, or (ii) 'at infinity', prescribing the asymptotic
behaviour of the solution. We argue that manifolds with corners should be used
for (i), and with a-corners for (ii). We discuss many applications of manifolds
with a-corners in boundary problems of type (ii), and to singular p.d.e.
problems involving 'bubbling', 'neck-stretching' and 'gluing'.


title: Detection of gamma rays of likely jet origin in Cygnus X-1

abstract:
  Aims: Probe the high-energy ($>$60 MeV) emission from the black hole X-ray
binary system, Cygnus X-1, and investigate its origin. Methods: We analysed 7.5
yr of data by Fermi/LAT with the latest PASS8 software version. Results: We
report the detection of a signal at $\sim$8 $\sigma$ statistical significance
spatially coincident with Cygnus X-1 and a luminosity above 60 MeV of
5.5$\times$10$^{33}$ erg s$^{-1}$. The signal is correlated with the hard X-ray
flux: the source is observed at high energies only during the hard X-ray
spectral state, when the source is known to display persistent, relativistic
radio emitting jets. The energy spectrum, extending up to $\sim$20 GeV without
any sign of spectral break, is well fitted by a power-law function with a
photon index of 2.3$\pm$0.2. There is a hint of orbital flux variability, with
high-energy emission mostly coming around the superior conjunction.
Conclusions: We detected GeV emission from Cygnus X-1 and probed that the
emission is most likely associated with the relativistic jets. The evidence of
flux orbital variability points to the anisotropic inverse Compton on stellar
photons as the mechanism at work, thus constraining the emission region to a
distance $10^{11}-10^{13}$ cm from the black hole.


title:
Effect of the polydispersity of a colloidal drop on the drying induced
  stress as measured by the buckling of a floating sheet

abstract:
  We study the stress developed during the drying of a colloidal drop of silica
nanoparticles. In particular, we use the wrinkling instability of a thin
floating sheet to measure the net stress applied by the deposit on the
substrate and we focus on the effect of the particle polydispersity. In the
case of a bidisperse suspension, we show that a small number of large particles
substantially decreases the expected stress, which we interpret as the
formation of lower hydrodynamic resistance paths in the porous material. As
colloidal suspensions are usually polydisperse, we show for different average
particle sizes that the stress is effectively dominated by the larger particles
of the distribution and not by the average particle size.


title:
Uniform parameterization of subanalytic sets and diophantine
  applications

abstract:
  We prove new parameterization theorems for sets definable in the structure
$\mathbb{R}_{an}$ (i.e. for globally subanalytic sets) which are uniform for
definable families of such sets. We treat both $C^r$-parameterization and
(mild) analytic parameterization. In the former case we establish a polynomial
(in $r$) bound (depending only on the given family) for the number of
parameterizing functions. However, since uniformity is impossible in the latter
case (as was shown by Yomdin via a very simple family of algebraic sets), we
introduce a new notion, analytic quasi-parameterization (where many-valued
complex analytic functions are used), which allows us to recover a uniform
result. We then give some diophantine applications motivated by the question as
to whether the $H^{o(1)}$ bound in the Pila-Wilkie counting theorem can be
improved, at least for certain reducts of $\mathbb{R}_{an}$. Both
parameterization results are shown to give uniform $(\log H)^{O(1)}$ bounds for
the number of rational points of height at most $H$ on
$\mathbb{R}_{an}$-definable Pfaffian surfaces. The quasi-parameterization
technique produces the sharper result, but the uniform $C^r$-parametrization
theorem has the advantage of also applying to $\mathbb{R}_{an}^{pow}$-definable
families.


title: Volumes of representations and birationality of the peripheral holonomy

abstract:
  We discuss here a generalization of a theorem by Dunfield stating that the
peripheral holonomy map, from the character variety of a 3-manifold to the
A-polynomial is birational. Dunfield's proof involves the rigidity of maximal
volume. The volume is still an important ingredient in this paper.
Unfortunately at this point no complete proof is done. Instead, a conjecture is
stated about the volume function on the character variety that would imply the
generalized birationality result.


title: Bayesian Variable Selection for Globally Sparse Probabilistic PCA

abstract:
  Sparse versions of principal component analysis (PCA) have imposed themselves
as simple, yet powerful ways of selecting relevant features of high-dimensional
data in an unsupervised manner. However, when several sparse principal
components are computed, the interpretation of the selected variables is
difficult since each axis has its own sparsity pattern and has to be
interpreted separately. To overcome this drawback, we propose a Bayesian
procedure called globally sparse probabilistic PCA (GSPPCA) that allows to
obtain several sparse components with the same sparsity pattern. This allows
the practitioner to identify the original variables which are relevant to
describe the data. To this end, using Roweis' probabilistic interpretation of
PCA and a Gaussian prior on the loading matrix, we provide the first exact
computation of the marginal likelihood of a Bayesian PCA model. To avoid the
drawbacks of discrete model selection, a simple relaxation of this framework is
presented. It allows to find a path of models using a variational
expectation-maximization algorithm. The exact marginal likelihood is then
maximized over this path. This approach is illustrated on real and synthetic
data sets. In particular, using unlabeled microarray data, GSPPCA infers much
more relevant gene subsets than traditional sparse PCA algorithms.


title:
Interpreting the librations of a synchronous satellite -- How their
  phase assesses Mimas' global ocean

abstract:
  Most of the main planetary satellites of our Solar System are expected to be
in synchronous rotation, the departures from the strict synchronicity being a
signature of the interior. Librations have been measured for the Moon, Phobos,
and some satellites of Saturn. I here revisit the theory of the longitudinal
librations in considering that part of the interior is not hydrostatic, i.e.
has not been shaped by the rotational and tidal deformations, but is fossil.
This consideration affects the rotational behavior. For that, I derive the
tensor of inertia of the satellite in splitting these two parts, before
proposing an analytical solution that I validate with numerical simulations. I
apply this new theory on Mimas and Epimetheus, for which librations have been
measured from Cassini data. I show that the large measured libration amplitude
of these bodies can be explained by an excess of triaxiality that would not
result from the hydrostatic theory. This theory cannot explain the phase shift
which has been measured in the diurnal librations of Mimas. This speaks against
a solid structure for Mimas, i.e. Mimas could have a global internal ocean.


title: E6Tensors: A Mathematica Package for E6 Tensors

abstract:
  We present the Mathematica package E6Tensors, a tool for explicit tensor
calculations in E6 gauge theories. In addition to matrix expressions for the
group generators of E6, it provides structure constants, various higher rank
tensors and expressions for the representations 27, 78, 351 and 351'. This
paper comes along with a short manual including physically relevant examples. I
further give a complete list of gauge invariant, renormalisable terms for
superpotentials and Lagrangians.


title:
Numerical simulation of nonlinear continuity equations by evolving
  diffeomorphisms

abstract:
  In this paper we present a numerical scheme for nonlinear continuity
equations, which is based on the gradient flow formulation of an energy
functional with respect to the quadratic transportation distance. It can be
applied to a large class of nonlinear continuity equations, whose dynamics are
driven by internal energies, given external potentials and/or interaction
energies. The solver is based on its variational formulation as a gradient flow
with respect to the Wasserstein distance. Positivity of solutions as well as
energy decrease of the semi-discrete scheme are guaranteed by its construction.
We illustrate this properties with various examples in spatial dimension one
and two.


title:
First-principles analysis of the efficiency of photovoltaic layers for
  CuAu-like chalcogenides and silicon

abstract:
  Chalcopyrite semiconductors are of considerable interest for application as
absorber layers in thin-film photovoltaic cells. When growing films of these
compounds, however, they are often found to contain CuAu- like domains, a
metastable phase of chalcopyrite. It has been reported that for CuInS2, the
presence of the CuAu-like phase improves the short circuit current of the
chalcopyrite-based photovoltaic cell. We investigate the thermodynamic
stability of both phases for a selected list of I-III-VI2 materials using a
first-principles density functional theory approach. For the CuIn-VI2
compounds, the difference in formation energy between the chalcopyrite and
CuAu-like phase is found to be close to 2 meV/atom, indicating a high
likelihood of the presence of CuAu-like domains. Next, we calculate the
Spectroscopic Limited Maximum Efficiency (SLME) of the CuAu- like phase and
compare the results with those of the corresponding chalcopyrite phase. We
identify several candidates with a high efficiency, such as CuAu-like CuInS2,
for which we obtain an SLME of 29% at a thickness of 500 nm. We observe that
the SLME can have values above the Shockley-Queisser (SQ) limit, and show that
this can occur because the SQ limit assumes the absorptivity to be a step
function, thus overestimating the radiative recombination in the detailed
balance approach. This means that it is possible to find higher theoretical
efficiencies within this framework simply by calculating the J-V characteristic
with an absorption spectrum. Finally, we expand our SLME analysis to indirect
band gap absorbers by studying silicon, and find that the SLME quickly
overestimates the reverse saturation current of indirect band gap materials,
drastically lowering their calculated efficiency.


title: Matching Handwritten Document Images

abstract:
  We address the problem of predicting similarity between a pair of handwritten
document images written by different individuals. This has applications related
to matching and mining in image collections containing handwritten content. A
similarity score is computed by detecting patterns of text re-usages between
document images irrespective of the minor variations in word morphology, word
ordering, layout and paraphrasing of the content. Our method does not depend on
an accurate segmentation of words and lines. We formulate the document matching
problem as a structured comparison of the word distributions across two
document images. To match two word images, we propose a convolutional neural
network (CNN) based feature descriptor. Performance of this representation
surpasses the state-of-the-art on handwritten word spotting. Finally, we
demonstrate the applicability of our method on a practical problem of matching
handwritten assignments.


title: Exploiting Equitable Partitions for Efficient Block Triangularization

abstract:
  In graph theory a partition of the vertex set of a graph is called equitable
if for all pairs of cells all vertices in one cell have an equal number of
neighbours in the other cell. Considering the implications for the adjacency
matrix one may generalize that concept as a block partition of a complex square
matrix s.t. each block has constant row sum. It is well known that replacing
each block by its row sum yields a smaller matrix whose multiset of eigenvalues
is contained in the initial spectrum. We generalize this approach to weighted
row sums and rectangular matrices and derive an efficient unitary
transformation which approximately block triangularizes a matrix w.r.t. an
arbitrary partition. Singular values and Hermiticity (if present) are
preserved. The approximation is exact in the equitable case and the error can
be bounded in terms of unitarily invariant matrix norms.


title: Transcritical bifurcation without parameters in memristive circuits

abstract:
  The transcritical bifurcation without parameters (TBWP) describes a stability
change along a line of equilibria, resulting from the loss of normal
hyperbolicity at a given point of such a line. Memristive circuits
systematically yield manifolds of non-isolated equilibria, and in this paper we
address a systematic characterization of the TBWP in circuits with a single
memristor. To achieve this we develop two mathematical results of independent
interest; the first one is an extension of the TBWP theorem to explicit
ordinary differential equations (ODEs) in arbitrary dimension; the second
result drives the characterization of this phenomenon to semiexplicit
differential-algebraic equations (DAEs), which provide the appropriate
framework for the analysis of circuit dynamics. In the circuit context the
analysis is performed in graph-theoretic terms: in this setting, our first
working scenario is restricted to passive problems (exception made of the
bifurcating memristor), and in a second step some results are presented for the
analysis of non-passive cases. The latter context is illustrated by means of a
memristive neural network model.


title: Sharpness of the phase transition for continuum percolation in R^2

abstract:
  We study the phase transition of random radii Poisson Boolean percolation:
Around each point of a planar Poisson point process, we draw a disc of random
radius, independently for each point. The behavior of this process is well
understood when the radii are uniformly bounded from above. In this article, we
investigate this process for unbounded (and possibly heavy tailed) radii
distributions. Under mild assumptions on the radius distribution, we show that
both the vacant and occupied sets undergo a phase transition at the same
critical parameter $\lambda_c$. Moreover,
  - For $\lambda < \lambda_c$, the vacant set has a unique unbounded connected
component and we give precise bounds on the one-arm probability for the
occupied set, depending on the radius distribution.
  - At criticality, we establish the box-crossing property, implying that no
unbounded component can be found, neither in the occupied nor the vacant sets.
We provide a polynomial decay for the probability of the one-arm events, under
sharp conditions on the distribution of the radius.
  - For $\lambda > \lambda_c$, the occupied set has a unique unbounded
component and we prove that the one-arm probability for the vacant decays
exponentially fast.
  The techniques we develop in this article can be applied to other models such
as the Poisson Voronoi and confetti percolation.


title: A new approach to Catalan numbers using differential equations

abstract:
  In this paper, we introduce two differential equations arising from the
generating function of the Catalan numbers which are `inverses' to each other
in some sense. From these differential equations, we obtain some new and
explicit identities for Catalan and higher-order Catalan numbers. In addition,
by other means than differential equations we also derive some interesting
identities involving Catalan numbers which are of arithmetic and combinatorial
nature.


title: Stringent theoretical and experimental bounds on graviton mass

abstract:
  We show from theoretical considerations, that if the graviton is massive, its
mass is constrained to be about $10^{-32}~eV/c^2$. This estimate is consistent
with those obtained from experiments, including the recent gravitational wave
detection in advanced LIGO.


title: An Algebraic Geometric Approach to Nivat's Conjecture

abstract:
  We study multidimensional configurations (infinite words) and subshifts of
low pattern complexity using tools of algebraic geometry. We express the
configuration as a multivariate formal power series over integers and
investigate the setup when there is a non-trivial annihilating polynomial: a
non-zero polynomial whose formal product with the power series is zero. Such
annihilator exists, for example, if the number of distinct patterns of some
finite shape $D$ in the configuration is at most the size $|D|$ of the shape.
This is our low pattern complexity assumption. We prove that the configuration
must be a sum of periodic configurations over integers, possibly with unbounded
values. As a specific application of the method we obtain an asymptotic version
of the well-known Nivat's conjecture: we prove that any two-dimensional,
non-periodic configuration can satisfy the low pattern complexity assumption
with respect to only finitely many distinct rectangular shapes $D$.


title:
Parametric and Probabilistic Model Checking of Confidentiality in Data
  Dispersal Algorithms (Extended Version)

abstract:
  Recent developments in cloud storage architectures have originated new models
of online storage as cooperative storage systems and interconnected clouds.
Such distributed environments involve many organizations, thus ensuring
confidentiality becomes crucial: only legitimate clients should recover the
information they distribute among storage nodes.
  In this work we present a unified framework for verifying confidentiality of
dispersal algorithms against probabilistic models of intruders. Two models of
intruders are given, corresponding to different types of attackers: one aiming
at intercepting as many slices of information as possible, and the other aiming
at attacking the storage providers in the network. Both try to recover the
original information, given the intercepted slices. By using probabilistic
model checking, we can measure the degree of confidentiality of the system
exploring exhaustively all possible behaviors. Our experiments suggest that
dispersal algorithms ensure a high degree of confidentiality against the slice
intruder, no matter the number of storage providers in the system. On the
contrary, they show a low level of confidentiality against the provider
intruder in networks with few storage providers (e.g. interconnected cloud
storage solutions).


title: Completing Partial Latin Squares - Alternative Proof

abstract:
  The problem of completing a partially specified n by n Latin square is solved
by an alternative proof, based on filling the rows (or diagonals) from 1 to n,
using an extended form of Hall's marriage theorem.


title: Pulsed quantum interaction between two distant mechanical oscillators

abstract:
  Feasible setup for pulsed quantum non-demolition interaction between two
distant mechanical oscillators through optical or microwave mediator is
proposed. The proposal uses homodyne measurement of the mediator and
feedforward control of the mechanical oscillators to reach the interaction. To
verify quantum nature of the interaction, we investigate the Gaussian
entanglement generated in the mechanical modes. We evaluate it under influence
of mechanical bath and propagation loss for the mediator and propose ways to
optimize the interaction. Finally, both currently available optomechanical and
electromechanical platforms are numerically analyzed. The analysis shows that
implementation is already feasible with current technology.


title: Pseudo-Bayesian Quantum Tomography with Rank-adaptation

abstract:
  Quantum state tomography, an important task in quantum information
processing, aims at reconstructing a state from prepared measurement data.
Bayesian methods are recognized to be one of the good and reliable choice in
estimating quantum states~\cite{blume2010optimal}. Several numerical works
showed that Bayesian estimations are comparable to, and even better than other
methods in the problem of $1$-qubit state recovery. However, the problem of
choosing prior distribution in the general case of $n$ qubits is not
straightforward. More importantly, the statistical performance of Bayesian type
estimators have not been studied from a theoretical perspective yet. In this
paper, we propose a novel prior for quantum states (density matrices), and we
define pseudo-Bayesian estimators of the density matrix. Then, using
PAC-Bayesian theorems, we derive rates of convergence for the posterior mean.
The numerical performance of these estimators are tested on simulated and real
datasets.

categories: math.ST math-ph math.MP quant-ph stat.TH


title:
First array of enriched Zn$^{82}$Se bolometers to search for double beta
  decay

abstract:
  The R&D activity performed during the last years proved the potential of ZnSe
scintillating bolometers to the search for neutrino-less double beta decay,
motivating the realization of the first large-mass experiment based on this
technology: CUPID-0. The isotopic enrichment in $^{82}$Se, the Zn$^{82}$Se
crystals growth, as well as the light detectors production have been
accomplished, and the experiment is now in construction at Laboratori Nazionali
del Gran Sasso (Italy). In this paper we present the results obtained testing
the first three Zn$^{82}$Se crystals operated as scintillating bolometers, and
we prove that their performance in terms of energy resolution, background
rejection capability and intrinsic radio-purity complies with the requirements
of CUPID-0.


title:
Detection of weak microwave fields with an underdamped Josephson
  junction

abstract:
  We have constructed a microwave detector based on the voltage switching of an
underdamped Josephson junction, that is positioned at a current antinode of a
{\lambda}/4 coplanar waveguide resonator. By measuring the switching current
and the transmission through a waveguide capacitively coupled to the resonator
at different drive frequencies and temperatures we are able to fully
characterize the system and assess its detection efficiency and sensitivity.
Testing the detector by applying a classical microwave field with the strength
of a single photon yielded a sensitivity parameter of 0.5 in qualitative
agreement with theoretical calculations.


title: Simulation study of a new InGaN p-layer free Schottky based solar cell

abstract:
  On the road towards next generation high efficiency solar cells, the ternary
Indium Gallium Nitride (InGaN) alloy is a good passenger since it allows to
cover the whole solar spectrum through the change in its Indium composition.
The choice of the main structure of the InGaN solar cell is however crucial.
Obtaining a high efficiency requires to improve the light absorption and the
photogenerated carriers collection that depend on the layers parameters,
including the Indium composition, p-and n-doping, device geometry.. .
Unfortunately, one of the main drawbacks of InGaN is linked to its p-type
doping, which is very difficult to realize since it involves complex
technological processes that are difficult to master and that highly impact the
layer quality. In this paper, the InGaN p-n junction (PN) and p-in junction
(PIN) based solar cells are numerically studied using the most realistic
models, and optimized through mathematically rigorous multivariate optimization
approaches. This analysis evidences optimal efficiencies of 17.8% and 19.0% for
the PN and PIN structures. It also leads to propose, analyze and optimize
player free InGaN Schottky-Based Solar Cells (SBSC): the Schottky structure and
a new MIN structure for which the optimal efficiencies are shown to be a little
higher than for the conventional structures: respectively 18.2% and 19.8%. The
tolerance that is allowed on each parameter for each of the proposed cells has
been studied. The new MIN structure is shown to exhibit the widest tolerances
on the layers thicknesses and dopings. In addition to its being player free,
this is another advantage of the MIN structure since it implies its better
reliability. Therefore, these new InGaN SBSC are shown to be alternatives to
the conventional structures that allow removing the p-type doping of InGaN
while giving photovoltaic (PV) performances at least comparable to the standard
multilayers PN or PIN structures.


abstract:
  Recent applications in computer vision have come to heavily rely on
superpixel over-segmentation as a pre-processing step for higher level vision
tasks, such as object recognition, image labelling or image segmentation. Here
we present a new superpixel algorithm called Hierarchical Piecewise-Constant
Super-regions (HPCS), which not only obtains superpixels comparable to the
state-of-the-art, but can also be applied hierarchically to form what we call
n-th order super-regions. In essence, a Markov Random Field (MRF)-based
anisotropic denoising formulation over the quantized feature space is adopted
to form piecewise-constant image regions, which are then combined with a
graph-based split & merge post-processing step to form superpixels. The graph
and quantized feature based formulation of the problem allows us to generalize
it hierarchically to preserve boundary adherence with fewer superpixels.
Experimental results show that, despite the simplicity of our framework, it is
able to provide high quality superpixels, and to hierarchically apply them to
form layers of over-segmentation, each with a decreasing number of superpixels,
while maintaining the same desired properties (such as adherence to strong
image edges). The algorithm is also memory efficient and has a low
computational cost.


title:
Non-modified Thermally-derived Onion-like Carbon As Electrocatalyst for
  [VO]2+/[VO2]+ Redox Flow Battery

abstract:
  We report the nanodiamond-derived onion-like carbon successfully applied as
an electrocatalyst for [VO]2+/[VO2]+ redox flow battery, as drop-coated (in the
as-synthesized state) on glassy carbon or carbon felt electrodes. We show that
its reversibility and catalytic activity in its as-synthesized state was
comparable to some of the best data in the literature which employed surface
modifications. We clarified the origin of such excellent performances by
physical/electrochemical analyses.


title: Formal-dual subsets of cyclic groups of prime power order

abstract:
  We study the notion of formal-duality over finite cyclic groups of prime
power order as introduced by Cohn, Kumar, Reiher and Sch\"urmann. We will prove
that for any cyclic group of odd prime power order, as well as for any cyclic
group of order $2^{2l+1}$, there is no primitive pair of formally-dual subsets.
This partially proves a conjecture, made by the priorly mentioned authors, that
the only cyclic groups with a pair of primitive formally-dual subsets are
$\{0\}$ and $\mathbb{Z}/4\mathbb{Z}$.


title:
If it does not kill them, it makes them stronger: collisional evolution
  of star clusters with tidal shocks

abstract:
  The radii of young (<100 Myr) star clusters correlate only weakly with their
masses. This shallow relation has been used to argue that impulsive tidal
perturbations, or `shocks', by passing giant molecular clouds (GMCs)
preferentially disrupt low-mass clusters. We show that this mass-radius
relation is in fact the result of the combined effect of two-body relaxation
and repeated tidal shocks. Clusters in a broad range of environments including
those like the solar neighbourhood evolve towards a typical radius of a few
parsecs, as observed, independent of the initial radius. This equilibrium
mass-radius relation is the result of a competition between expansion by
relaxation and shrinking due to shocks. Interactions with GMCs are more
disruptive for low-mass clusters, which helps to evolve the globular cluster
mass function (GCMF). However, the properties of the interstellar medium in
high-redshift galaxies required to establish a universal GCMF shape are more
extreme than previously derived, challenging the idea that all GCs formed with
the same power-law mass function.


title:
Space-time domain decomposition for advection-diffusion problems in
  mixed formulations

abstract:
  This paper is concerned with the numerical solution of porous-media flow and
transport problems , i. e. heterogeneous, advection-diffusion problems. Its aim
is to investigate numerical schemes for these problems in which different time
steps can be used in different parts of the domain. Global-in-time,
non-overlapping domain-decomposition methods are coupled with operator
splitting making possible the different treatment of the advection and
diffusion terms. Two domain-decomposition methods are considered: one uses the
time-dependent Steklov--Poincar{\'e} operator and the other uses optimized
Schwarz waveform relaxation (OSWR) based on Robin transmission conditions. For
each method, a mixed formulation of an interface problem on the space-time
interface is derived, and different time grids are employed to adapt to
different time scales in the subdomains. A generalized Neumann-Neumann
preconditioner is proposed for the first method. To illustrate the two methods
numerical results for two-dimensional problems with strong heterogeneities are
presented. These include both academic problems and more realistic prototypes
for simulations for the underground storage of nuclear waste.


title: Spectral properties of general hypergraphs

abstract:
  In this paper, we investigate spectral properties of the adjacency tensor,
Laplacian tensor and signless Laplacian tensor of general hypergraphs
(including uniform and non-uniform hypergraphs). We obtain some bounds for the
spectral radius of general hypergraphs in terms of vertex degrees, and give
spectral characterizations of odd-bipartite hypergraphs.


title: Viscous solution of the triple shock reflection problem

abstract:
  The reflection of a triple-shock configuration was studied numerically in two
dimensions using the Navier-Stokes equations. The flow field was initialized
using three shock theory, and the reflection of the triple point on a plane of
symmetry was studied. The conditions simulated a stoichiometric methane-oxygen
detonation cell at low pressure on time scales preceding ignition, when the gas
was assumed to be inert. Viscosity was found to play an important role on some
shock reflection mechanisms believed to accelerate reaction rates in
detonations when time scales are small. A small wall jet was present in the
double Mach reflection and increased in size with Reynolds number, eventually
forming a small vortex. Kelvin-Helmholtz instabilities were absent and there
was no Mach stem bifurcation at Reynolds numbers corresponding to when the Mach
stem had travelled distances on the scale of the induction length.
Kelvin-Helmholtz instabilities are found to not likely be a source of rapid
reactions in detonations at time scales commensurate with the ignition delay
behind the Mach stem.


title: Geometric Near-neighbor Access Tree (GNAT) revisited

abstract:
  Geometric Near-neighbor Access Tree (GNAT) is a metric space indexing method
based on hierarchical hyperplane partitioning of the space. While GNAT is very
efficient in proximity searching, it has a bad reputation of being a memory
hog. We show that this is partially based on too coarse analysis, and that the
memory requirements can be lowered while at the same time improving the search
efficiency. We also show how to make GNAT memory adaptive in a smooth way, and
that the hyperplane partitioning can be replaced with ball partitioning, which
can further improve the search performance. We conclude with experimental
results showing the new methods can give significant performance boost.


title: Multiple D3-instantons and mock modular forms I

abstract:
  We study D3-instanton corrections to the hypermultiplet moduli space in type
IIB string theory compactified on a Calabi-Yau threefold. In a previous work,
consistency of D3-instantons with S-duality was established at first order in
the instanton expansion, using the modular properties of the M5-brane elliptic
genus. We extend this analysis to the two-instanton level, where wall-crossing
phenomena start playing a role. We focus on the contact potential, an analogue
of the Kahler potential which must transform as a modular form under S-duality.
We show that it can be expressed in terms of a suitable modification of the
partition function of D4-D2-D0 BPS black holes, constructed out of the
generating function of MSW invariants (the latter coincide with
Donaldson-Thomas invariants in a particular chamber). Modular invariance of the
contact potential then requires that, in case where the D3-brane wraps a
reducible divisor, the generating function of MSW invariants must transform as
a vector-valued mock modular form, with a specific modular completion built
from the MSW invariants of the constituents. Physically, this gives a powerful
constraint on the degeneracies of BPS black holes. Mathematically, our result
gives a universal prediction for the modular properties of Donaldson-Thomas
invariants of pure two-dimensional sheaves.


title: Supersymmetric chameleons and ultra-local models

abstract:
  Super-chameleon models where all types of matter belong to three secluded
sectors, i.e. the dark, supersymmetry breaking and matter sectors, are shown to
be dynamically equivalent to ultra-local models of modified gravity. In the
dark sector, comprising both dark matter and dark energy, the interaction range
between the dark energy field and dark matter is constrained to be extremely
short, i.e. shorter than the inverse gravitino mass set by supersymmetry
breaking. This realises an extreme version of chameleon screening of the dark
energy interaction. On the other hand, the baryonic matter sector decouples
from the dark energy in a Damour-Polyakov way. These two mechanisms preclude
the existence of any modification of gravity locally in the Solar System due to
the presence of the super-chameleon field. On larger scales, the
super-chameleon can have effects on the growth of structure and the number of
dark matter halos. It can also affect the dynamics of galaxies where the fifth
force interaction that it induces can have the same order of magnitude as
Newton's interaction.


title: A quantum router for high-dimensional entanglement

abstract:
  In addition to being a workhorse for modern quantum technologies,
entanglement plays a key role in fundamental tests of quantum mechanics. The
entanglement of photons in multiple levels, or dimensions, explores the limits
of how large an entangled state can be, while also greatly expanding its
applications in quantum information. Here we show how a high-dimensional
quantum state of two photons entangled in their orbital angular momentum can be
split into two entangled states with a smaller dimensionality structure. Our
work demonstrates that entanglement is a quantum property that can be
subdivided into spatially separated parts. In addition, our technique has vast
potential applications in quantum as well as classical communication systems.


title: Magnetoelectroluminescence in organic light emitting diodes

abstract:
  The magnetoelectroluminescence of conjugated organic polymer films is widely
accepted to arise from a polaron pair mechanism, but their magnetoconductance
is less well understood. Here we derive a new relationship between the
experimentally measurable magnetoelectroluminescence and magnetoconductance and
the theoretically calculable singlet yield of the polaron pair recombination
reaction. This relationship is expected to be valid regardless of the mechanism
of the magnetoconductance, provided the mobilities of the free polarons are
independent of the applied magnetic field (i.e., provided one discounts the
possibility of spin-dependent transport). We also discuss the semiclassical
calculation of the singlet yield of the polaron pair recombination reaction for
materials such as poly(2,5-dioctyloxy-paraphenylene vinylene) (DOO-PPV), the
hyperfine fields in the polarons of which can be extracted from light-induced
electron spin resonance measurements. The resulting theory is shown to give
good agreement with experimental data for both normal (H-) and deuterated (D-)
DOO-PPV over a wide range of magnetic field strengths once singlet-triplet
dephasing is taken into account. Without this effect, which has not been
included in any previous simulation of magnetoelectroluminescence, it is not
possible to reproduce the experimental data for both isotopologues in a
consistent fashion. Our results also indicate that the magnetoconductance of
DOO-PPV cannot be solely due to the effect of the magnetic field on the
dissociation of polaron pairs.


title: Quantum enhanced feedback cooling of a mechanical oscillator

abstract:
  Laser cooling is a fundamental technique used in primary atomic frequency
standards, quantum computers, quantum condensed matter physics and tests of
fundamental physics, among other areas. It has been known since the early 1990s
that laser cooling can, in principle, be improved by using squeezed light as an
electromagnetic reservoir; while quantum feedback control using a squeezed
light probe is also predicted to allow improved cooling. Here, we implement
quantum feedback control of a micro-mechanical oscillator for the first time
with a squeezed probe field. This allows quantum-enhanced feedback cooling with
a measurement rate greater than it is possible with classical light, and a
consequent reduction in the final oscillator temperature. Our results have
significance for future applications in areas ranging from quantum information
networks, to quantum-enhanced force and displacement measurements and
fundamental tests of macroscopic quantum mechanics.


title: Interactive Debugging of Knowledge Bases

abstract:
  Many AI applications rely on knowledge about a relevant real-world domain
that is encoded by means of some logical knowledge base (KB). The most
essential benefit of logical KBs is the opportunity to perform automatic
reasoning to derive implicit knowledge or to answer complex queries about the
modeled domain. The feasibility of meaningful reasoning requires KBs to meet
some minimal quality criteria such as logical consistency. Without adequate
tool assistance, the task of resolving violated quality criteria in KBs can be
extremely tough even for domain experts, especially when the problematic KB
includes a large number of logical formulas or comprises complicated logical
formalisms.
  Published non-interactive debugging systems often cannot localize all
possible faults (incompleteness), suggest the deletion or modification of
unnecessarily large parts of the KB (non-minimality), return incorrect
solutions which lead to a repaired KB not satisfying the imposed quality
requirements (unsoundness) or suffer from poor scalability due to the inherent
complexity of the KB debugging problem. Even if a system is complete and sound
and considers only minimal solutions, there are generally exponentially many
solution candidates to select one from. However, any two repaired KBs obtained
from these candidates differ in their semantics in terms of entailments and
non-entailments. Selection of just any of these repaired KBs might result in
unexpected entailments, the loss of desired entailments or unwanted changes to
the KB.
  This work proposes complete, sound and optimal methods for the interactive
debugging of KBs that suggest the one (minimally invasive) error correction of
the faulty KB that yields a repaired KB with exactly the intended semantics.
Users, e.g. domain experts, are involved in the debugging process by answering
automatically generated queries about the intended domain.


title:
Resonance fluorescence of a laser cooled atom in a non-harmonic
  potential

abstract:
  We investigate a single laser driven atom trapped in a non-harmonic
potential. We present the performance of ground-state laser cooling and Doppler
cooling and the signatures of the center-of-mass motion in the power spectrum
of the scattered light. In order to illustrate the results we provide two
explicit examples for the confining potential: the infinite square well and the
Morse potential.


title:
The magnetic susceptibility on the transverse antiferromagnetic Ising
  model: Analysis of the reentrant behaviour

abstract:
  We study the three-dimensional antiferromagnetic Ising model in both uniform
longitudinal ($H$) and transverse ($\Omega $) magnetic fields by using the
effective-field theory with finite cluster $N=1$ spin (EFT-1). We analyzed the
behavior of the magnetic susceptibility to investigate the reentrant phenomena
we have seen the same phase diagram previously obtained in another papers. Our
results shows the presence of two divergences in the susceptibility that
indicates the existence of a reentrant behaviour.


title: On centers of blocks with one simple module

abstract:
  Let G be a finite group, and let B be a non-nilpotent block of G with respect
to an algebraically closed field of characteristic 2. Suppose that B has an
elementary abelian defect group of order 16 and only one simple module. The
main result of this paper describes the algebra structure of the center of B.
This is motivated by a similar analysis of a certain 3-block of defect 2 in
[Kessar, 2012].


title: Multiquark Hadrons - A New Facet of QCD

abstract:
  I review some selected aspects of the phenomenology of multiquark states
discovered in high energy experiments. They have four valence quarks (called
tetraquarks) and two of them are found to have five valence quarks (called
pentaquarks), extending the conventional hadron spectrum which consists of
quark-antiquark $(q\bar{q})$ mesons and $qqq$ baryons. Multiquark states
represent a new facet of QCD and their dynamics is both challenging and
currently poorly understood. I discuss various approaches put forward to
accommodate them, with emphasis on the diquark model.


title: Lower bound for the regularity index of fat points

abstract:
  The problem to find an upper bound for the regularity index of fat points has
been dealt with by many authors. In this paper we give a lower bound for the
regularity index of fat points. It is useful for determining the regularity
index.


title: Macroscopic Quantum Measurements of noncommuting observables

abstract:
  Assuming a well-behaving quantum-to-classical transition, measuring large
quantum systems should be highly informative with low measurement-induced
disturbance, while the coupling between system and measurement apparatus is
"fairly simple" and weak. Here, we show that this is indeed possible within the
formalism of quantum mechanics. We discuss an example of estimating the
collective magnetization of a spin ensemble by simultaneous measuring three
orthogonal spin directions. For the task of estimating the direction of a
spin-coherent state, we find that the average guessing fidelity and the system
disturbance are nonmonotonic functions of the coupling strength. Strikingly, we
discover an intermediate regime for the coupling strength where the guessing
fidelity is quasi-optimal, while the measured state is almost not disturbed.


title: Spatially Assisted Schwinger Mechanism and Magnetic Catalysis

abstract:
  Using the worldline formalism we compute an effective action for fermions
under a temporally modulated electric field and a spatially modulated magnetic
field. It is known that the former leads to an enhanced Schwinger Mechanism,
while we find that the latter can also result in enhanced particle production
and even cause a reorganization of the vacuum to acquire a larger dynamical
mass in equilibrium which spatially assists the Magnetic Catalysis.


title:
Threshold Perturbations in Current-Carrying Superconducting Bridges with
  a Finite Length near the Critical Temperature

abstract:
  Near the critical temperature of a superconducting transition, the energy of
the threshold perturbation $\delta F_{thr}$ that transfers a superconducting
bridge to a resistive state at a current below the critical current $I_c$ has
been determined. It has been shown that $\delta F_{thr}$ increases with a
decrease in the length of a bridge for short bridges with lengths $L<\xi$
(where $\xi$ is the coherence length) and is saturated for long bridges with
$L\gg \xi$. At certain geometrical parameters of banks and bridge, the function
$\delta F_{thr}(L)$ at the current $I\to 0$ has a minimum at $L\sim 2-3 \xi$.
These results indicate that the effect of fluctuations on Josephson junctions
made in the form of short superconducting bridges is reduced and that the
effect of fluctuations on bridges with lengths $\sim 2-3 \xi$ is enhanced.


title: On circular flows: linear stability and damping

abstract:
  In this article we establish linear inviscid damping with optimal decay rates
around 2D Taylor-Couette flow and similar monotone flows in an annular domain
$B_{r_{2}}(0) \setminus B_{r_{1}}(0) \subset \mathbb{R}^{2}$. Following recent
results by Wei, Zhang and Zhao, we establish stability in weighted norms, which
allow for a singularity formation at the boundary, and additional provide a
description of the blow-up behavior.


title: Statistical solutions of hyperbolic conservation laws I: Foundations

abstract:
  We seek to define statistical solutions of hyperbolic systems of conservation
laws as time-parametrized probability measures on $p$-integrable functions. To
do so, we prove the equivalence between probability measures on $L^p$ spaces
and infinite families of \textit{correlation measures}. Each member of this
family, termed a \textit{correlation marginal}, is a Young measure on a
finite-dimensional tensor product domain and provides information about
multi-point correlations of the underlying integrable functions. We also prove
that any probability measure on a $L^p$ space is uniquely determined by certain
moments (correlation functions) of the equivalent correlation measure.
  We utilize this equivalence to define statistical solutions of
multi-dimensional conservation laws in terms of an infinite set of equations,
each evolving a moment of the correlation marginal. These evolution equations
can be interpreted as augmenting entropy measure-valued solutions, with
additional information about the evolution of all possible multi-point
correlation functions. Our concept of statistical solutions can accommodate
uncertain initial data as well as possibly non-atomic solutions even for atomic
initial data.
  For multi-dimensional scalar conservation laws we impose additional entropy
conditions and prove that the resulting \textit{entropy statistical solutions}
exist, are unique and are stable with respect to the $1$-Wasserstein metric on
probability measures on $L^1$.


title: Coupling a thermal atomic vapor to an integrated ring resonator

abstract:
  Strongly interacting atom-cavity systems within a network with many nodes
constitute a possible realization for a quantum internet which allows for
quantum communication and computation on the same platform. To implement such
large-scale quantum networks, nanophotonic resonators are promising candidates
because they can be scalably fabricated and interconnected with waveguides and
optical fibers. By integrating arrays of ring resonators into a vapor cell we
show that thermal rubidium atoms above room temperature can be coupled to
photonic cavities as building blocks for chip-scale hybrid circuits. Although
strong coupling is not yet achieved in this first realization, our approach
provides a key step towards miniaturization and scalability of atom-cavity
systems.


title:
Quantifying Model Form Uncertainty in RANS Simulation of Wing-Body
  Junction Flow

abstract:
  Wing-body junction flows occur when a boundary layer encounters an airfoil
mounted on the surface. The corner flow near the trailing edge is challenging
for the linear eddy viscosity Reynolds Averaged Navier-Stokes (RANS) models,
due to the interaction of two perpendicular boundary layers which leads to
highly anisotropic Reynolds stress at the near wall region. Recently, Xiao et
al. proposed a physics-informed Bayesian framework to quantify and reduce the
model-form uncertainties in RANS simulations by utilizing sparse observation
data. In this work, we extend this framework to incorporate the use of wall
function in RANS simulations, and apply the extended framework to the RANS
simulation of wing-body junction flow. Standard RANS simulations are performed
on a 3:2 elliptic nose and NACA0020 tail cylinder joined at their maximum
thickness location. Current results show that both the posterior mean velocity
and the Reynolds stress anisotropy show better agreement with the experimental
data at the corner region near the trailing edge. On the other hand, the prior
velocity profiles at the leading edge indicate the restriction of uncertainty
space and the performance of the framework at this region is less effective. By
perturbing the orientation of Reynolds stress, the uncertainty range of prior
velocity profiles at the leading edge covers the experimental data. It
indicates that the uncertainty of RANS predicted velocity field is more related
to the uncertainty in the orientation of Reynolds stress at the region with
rapid change of mean strain rate. The present work not only demonstrates the
capability of Bayesian framework in improving the RANS simulation of wing-body
junction flow, but also reveals the major source of model-form uncertainty for
this flow, which can be useful in assisting RANS modeling.


title: Montre: A Tool for Monitoring Timed Regular Expressions

abstract:
  We present Montre, a monitoring tool to search patterns specified by timed
regular expressions over real-time behaviors. We use timed regular expressions
as a compact, natural, and highly-expressive pattern specification language for
monitoring applications involving quantitative timing constraints. Our tool
essentially incorporates online and offline timed pattern matching algorithms
so it is capable of finding all occurrences of a given pattern over both logged
and streaming behaviors. Furthermore, Montre is designed to work with other
tools via standard interfaces to perform more complex and versatile tasks for
analyzing and reasoning about cyber-physical systems. As the first of its kind,
we believe Montre will enable a new line of inquiries and techniques in these
fields.


title:
Magnetic field in atypical prominence structures: Bubble, tornado and
  eruption

abstract:
  Spectropolarimetric observations of prominences have been obtained with the
THEMIS telescope during four years of coordinated campaigns. Our aim is now to
understand the conditions of the cool plasma and magnetism in `atypical'
prominences, namely when the measured inclination of the magnetic field
departs, to some extent, from the predominantly horizontal field found in
`typical' prominences. What is the role of the magnetic field in these
prominence types? Are plasma dynamics more important in these cases than the
magnetic support? We focus our study on three types of `atypical' prominences
(tornadoes, bubbles and jet-like prominence eruptions) that have all been
observed by THEMIS in the He I D_3 line, from which the Stokes parameters can
be derived. The magnetic field strength, inclination and azimuth in each pixel
are obtained by using the Principal Component Analysis inversion method on a
model of single scattering in the presence of the Hanle effect. The magnetic
field in tornadoes is found to be more or less horizontal, whereas for the
eruptive prominence it is mostly vertical. We estimate a tendency towards
higher values of magnetic field strength inside the bubbles than outside in the
surrounding prominence. In all of the models in our database, only one magnetic
field orientation is considered for each pixel. While sufficient for most of
the main prominence body, this assumption appears to be oversimplified in
atypical prominence structures. We should consider these observations as the
result of superposition of multiple magnetic fields, possibly even with a
turbulent field component.


title: Transversal fluctuations for a first passage percolation model

abstract:
  We introduce a new first passage percolation model in a Poissonian
environment on $\mathbb{R}^{2}$. In this model, the action of a path depends on
the geometry of the path and the travel time. We prove that the transversal
fluctuation exponent for point-to-line action minimizers is at least $3/5$.


title:
Dynamic Bayesian Networks to simulate occupant behaviours in office
  buildings related to indoor air quality

abstract:
  This paper proposes a new general approach based on Bayesian networks to
model the human behaviour. This approach represents human behaviour with
probabilistic cause-effect relations based on knowledge, but also with
conditional probabilities coming either from knowledge or deduced from
observations. This approach has been applied to the co-simulation of the CO2
concentration in an office coupled with human behaviour.


title:
Contour-based 3d tongue motion visualization using ultrasound image
  sequences

abstract:
  This article describes a contour-based 3D tongue deformation visualization
framework using B-mode ultrasound image sequences. A robust, automatic tracking
algorithm characterizes tongue motion via a contour, which is then used to
drive a generic 3D Finite Element Model (FEM). A novel contour-based 3D dynamic
modeling method is presented. Modal reduction and modal warping techniques are
applied to model the deformation of the tongue physically and efficiently. This
work can be helpful in a variety of fields, such as speech production, silent
speech recognition, articulation training, speech disorder study, etc.


title: Large-scale Join-Idle-Queue system with general service times

abstract:
  A parallel server system with $n$ identical servers is considered. The
service time distribution has a finite mean $1/\mu$, but otherwise is
arbitrary. Arriving customers are be routed to one of the servers immediately
upon arrival. Join-Idle-Queue routing algorithm is studied, under which an
arriving customer is sent to an idle server, if such is available, and to a
randomly uniformly chosen server, otherwise. We consider the asymptotic regime
where $n\to\infty$ and the customer input flow rate is $\lambda n$. Under the
condition $\lambda/\mu<1/2$, we prove that, as $n\to\infty$, the sequence of
(appropriately scaled) stationary distributions concentrates at the natural
equilibrium point, with the fraction of occupied servers being constant equal
$\lambda/\mu$. In particular, this implies that the steady-state probability of
an arriving customer waiting for service vanishes.


title: Randomized Primal-Dual Proximal Block Coordinate Updates

abstract:
  In this paper we propose a randomized primal-dual proximal block coordinate
updating framework for a general multi-block convex optimization model with
coupled objective function and linear constraints. Assuming mere convexity, we
establish its $O(1/t)$ convergence rate in terms of the objective value and
feasibility measure. The framework includes several existing algorithms as
special cases such as a primal-dual method for bilinear saddle-point problems
(PD-S), the proximal Jacobian ADMM (Prox-JADMM) and a randomized variant of the
ADMM method for multi-block convex optimization. Our analysis recovers and/or
strengthens the convergence properties of several existing algorithms. For
example, for PD-S our result leads to the same order of convergence rate
without the previously assumed boundedness condition on the constraint sets,
and for Prox-JADMM the new result provides convergence rate in terms of the
objective value and the feasibility violation. It is well known that the
original ADMM may fail to converge when the number of blocks exceeds two. Our
result shows that if an appropriate randomization procedure is invoked to
select the updating blocks, then a sublinear rate of convergence in expectation
can be guaranteed for multi-block ADMM, without assuming any strong convexity.
The new approach is also extended to solve problems where only a stochastic
approximation of the (sub-)gradient of the objective is available, and we
establish an $O(1/\sqrt{t})$ convergence rate of the extended approach for
solving stochastic programming.


title: The reverse Yang-Mills-Higgs flow in a neighbourhood of a critical point

abstract:
  The main result of this paper is a construction of solutions to the reverse
Yang-Mills-Higgs flow converging in the $C^\infty$ topology to a critical
point. The construction uses only the complex gauge group action, which leads
to an algebraic classification of the isomorphism classes of points in the
unstable set of a critical point in terms of a filtration of the underlying
Higgs bundle.
  Analysing the compatibility of this filtration with the
Harder-Narasimhan-Seshadri double filtration gives an algebraic criterion for
two critical points to be connected by a flow line. As an application, we can
use this to construct Hecke modifications of Higgs bundles via the
Yang-Mills-Higgs flow. When the Higgs field is zero (corresponding to the
Yang-Mills flow), this criterion has a geometric interpretation in terms of
secant varieties of the projectivisation of the underlying bundle inside the
unstable manifold of a critical point, which gives a precise description of
broken and unbroken flow lines connecting two critical points. For non-zero
Higgs field, at generic critical points the analogous interpretation involves
the secant varieties of the spectral curve of the Higgs bundle.


title:
Testing Feedback-Modified Dark Matter Haloes with Galaxy Rotation
  Curves: Estimation of Halo Parameters and Consistency with $\Lambda$CDM

abstract:
  Cosmological $N$-body simulations predict dark matter (DM) haloes with steep
central cusps (e.g. NFW, Navarro et al. 1996). This contradicts observations of
gas kinematics in low-mass galaxies that imply the existence of shallow DM
cores. Baryonic processes such as adiabatic contraction and gas outflows can,
in principle, alter the initial DM density profile, yet their relative
contributions to the halo transformation remain uncertain. Recent high
resolution, cosmological hydrodynamic simulations (Di Cintio et al. 2014, DC14)
predict that inner density profiles depend systematically on the ratio of
stellar to DM mass (M$_*$/M$_{\text{halo}}$). Using a Markov Chain Monte Carlo
approach, we test the NFW and the M$_*$/M$_{\text{halo}}$-dependent DC14 halo
models against a sample of 147 galaxy rotation curves from the new {\it
Spitzer} Photometry and Accurate Rotation Curves (SPARC) data set. These
galaxies all have extended H{\small I} rotation curves from radio
interferometry as well as accurate stellar mass density profiles from
near-infrared photometry. The DC14 halo profile provides markedly better fits
to the data compared to the NFW profile. Unlike NFW, the DC14 halo parameters
found in our rotation curve fits naturally fall within two standard deviations
of the mass-concentration relation predicted by $\Lambda$CDM and the stellar
mass-halo mass relation inferred from abundance matching with few outliers.
Halo profiles modified by baryonic processes are therefore more consistent with
expectations from $\Lambda$ cold dark matter ($\Lambda$CDM) cosmology and
provide better fits to galaxy rotation curves across a wide range of galaxy
properties than do halo models that neglect baryonic physics. Our results offer
a solution to the decade long cusp-core discrepancy.


title: On the Genericity of Maximum Rank Distance and Gabidulin Codes

abstract:
  We consider linear rank-metric codes in $\mathbb F_{q^m}^n$. We show that the
properties of being MRD (maximum rank distance) and non-Gabidulin are generic
over the algebraic closure of the underlying field, which implies that over a
large extension field a randomly chosen generator matrix generates an MRD and a
non-Gabidulin code with high probability. Moreover, we give upper bounds on the
respective probabilities in dependence on the extension degree $m$.


title: WarmAndFuzzy: the halo model beyond CDM

abstract:
  Cold dark matter (CDM) is a well established paradigm to describe
cosmological structure formation, and works extraordinarily well on large,
linear, scales. Progressing further in dark matter physics requires being able
to understand structure formation in the non-linear regime, both for CDM and
its alternatives. This short note describes a calculation, and accompanying
code, WarmAndFuzzy, incorporating the popular models of warm and fuzzy dark
matter (WDM and FDM) into the standard halo model to compute the non-linear
matter power spectrum. The FDM halo model power spectrum has not been computed
before. The FDM implementation models ultralight axions and other scalar fields
with $m_a\approx 10^{-22}\text{ eV}$. The WDM implementation models thermal WDM
with mass $m_X\approx 1\text{ keV}$. The halo model shows that differences
between WDM, FDM, and CDM survive at low redshifts in the quasi-linear and
fully non-linear regimes. The code uses analytic transfer functions for the
linear power spectrum, modified collapse barriers in the halo mass function,
and a modified concentration-mass relationship for the halo density profiles.
Modified halo density profiles (for example, cores) are not included, but are
under development. Cores are expected to have very minor effects on the power
spectrum on observable scales. Applications of this code to the Lyman-$\alpha$
forest flux power spectrum and the cosmic microwave background lensing power
spectrum will be discussed in companion papers. \textsc{WarmAndFuzzy} is
available online at \url{https://github.com/DoddyPhysics/HMcode}, where
collaboration in development is welcomed.

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


title: Vector perturbations of galaxy number counts

abstract:
  We derive the contribution to relativistic galaxy number count fluctuations
from vector and tensor perturbations within linear perturbation theory. Our
result is consistent with the the relativistic corrections to number counts due
to scalar perturbation, where the Bardeen potentials are replaced with
line-of-sight projection of vector and tensor quantities. Since vector and
tensor perturbations do not lead to density fluctuations the standard density
term in the number counts is absent. We apply our results to vector
perturbations which are induced from scalar perturbations at second order and
give numerical estimates of their contributions to the power spectrum of
relativistic galaxy number counts.


title: Towards the fundamental spectrum of the Quantum Yang-Mills Theory

abstract:
  In this work we focus on the quantum Einstein-Yang-Mills sector quantised by
the methods of Loop Quantum Gravity (LQG). We point out the improved UV
behaviour of the coupled system as compared to pure quantum Yang-Mills theory
on a fixed, classical background spacetime as was considered in a seminal work
by Kogut and Susskind. Furthermore, we develop a calculational scheme by which
the fundamental spectrum of the quantum Yang-Mills Hamiltonian can be computed
in principle and by which one can make contact to the Wilsonian renormalization
group, possibly purely within the Hamiltonian framework. Finally, we comment on
the relation of the fundamental spectrum to that of pure Yang-Mills theory on a
(flat) classical spacetime.


title: Double electron capture searches in $^{74}$Se

abstract:
  A search for various double electron capture modes of $^{74}$Se has been
performed using an ultralow background Ge-detector in the Felsenkeller
laboratory, Germany. Especially for the potentially resonant transition into
the 1204.2 keV excited state of $^{74}$Ge a lower half-life limit of $0.70\cdot
10^{19}$ yr (90% credibility) has been obtained. Serious concerns are raised
about the validity of obtained $^{74}$Se limits in some recent publications.


title: A Geometric Approach to Color Image Regularization

abstract:
  We present a new vectorial total variation method that addresses the problem
of color consistent image filtering. Our approach is inspired from the
double-opponent cell representation in the human visual cortex. Existing
methods of vectorial total variation regularizers have insufficient (or no)
coupling between the color channels and thus may introduce color artifacts. We
address this problem by introducing a novel coupling between the color channels
related to a pullback-metric from the opponent space to the data (RGB color)
space. Our energy is a non-convex, non-smooth higher-order vectorial total
variation approach and promotes color consistent image filtering via a coupling
term. For a convex variant, we show well-posedness and existence of a solution
in the space of vectorial bounded variation. For the higher-order scheme we
employ a half-quadratic strategy, which model the non-convex energy terms as
the infimum of a sequence of quadratic functions. In experiments, we elaborate
on traditional image restoration applications of inpainting, deblurring and
denoising. Regarding the latter, we demonstrate state of the art restoration
quality with respect to structure coherence and color consistency.


title:
Longitudinal spin-relaxation of donor-bound electrons in direct bandgap
  semiconductors

abstract:
  We measure the donor-bound electron longitudinal spin-relaxation time ($T_1$)
as a function of magnetic field ($B$) in three high-purity direct-bandgap
semiconductors: GaAs, InP, and CdTe, observing a maximum $T_1$ of
$1.4~\text{ms}$, $0.4~\text{ms}$ and $1.2~\text{ms}$, respectively. In GaAs and
InP at low magnetic field, up to $\sim2~\text{T}$, the spin-relaxation
mechanism is strongly density and temperature dependent and is attributed to
the random precession of the electron spin in hyperfine fields caused by the
lattice nuclear spins. In all three semiconductors at high magnetic field, we
observe a power-law dependence ${T_1 \propto B^{-\nu}}$ with ${3\lesssim \nu
\lesssim 4}$. Our theory predicts that the direct spin-phonon interaction is
important in all three materials in this regime in contrast to quantum dot
structures. In addition, the "admixture" mechanism caused by Dresselhaus
spin-orbit coupling combined with single-phonon processes has a comparable
contribution in GaAs. We find excellent agreement between high-field theory and
experiment for GaAs and CdTe with no free parameters, however a significant
discrepancy exists for InP.


title: On the UV dimensions of Loop Quantum Gravity

abstract:
  Planck-scale dynamical dimensional reduction is attracting more and more
interest in the quantum-gravity literature since it seems to be a model
independent effect. However different studies base their results on different
concepts of spacetime dimensionality. Most of them rely on the
\textit{spectral} dimension, others refer to the \textit{Hausdorff} dimension
and, very recently, it has been introduced also the \textit{thermal} dimension.
We here show that all these distinct definitions of dimension give the same
outcome in the case of the effective regime of Loop Quantum Gravity (LQG). This
is achieved by deriving a modified dispersion relation from the
hypersurface-deformation algebra with quantum corrections. Moreover we also
observe that the number of UV dimensions can be used to constrain the
ambiguities in the choice of these LQG-based modifications of the Dirac
spacetime algebra. In this regard, introducing the \textit{polymerization} of
connections i.e. $K \rightarrow \frac{\sin(\delta K)}{\delta}$, we find that
the leading quantum correction gives $d_{UV} = 2.5$. This result may indicate
that the running to the expected value of two dimensions is ongoing, but it has
not been completed yet. Finding $d_{UV}$ at ultra-short distances would require
to go beyond the effective approach we here present.


title: Emergent dark energy via decoherence in quantum interactions

abstract:
  In this work we consider a recent proposal in which gravitational
interactions are mediated via classical information and apply it to a
relativistic context. We study a toy model of a quantized
Friedman-Robertson-Walker (FRW) universe with the assumption that any test
particles must feel a classical metric. We show that such a model results in
decoherence in the FRW state that manifests itself as a dark energy fluid that
fills the spacetime. Analysis of the resulting fluid, shows the equation of
state asymptotically oscillates around the value $w=-1/3$, regardless of the
spatial curvature, which provides the bound between accelerating and
decelerating expanding FRW cosmologies. Motivated by quantum-classical
interactions this model is yet another example of theories with violation of
energy-momentum conservation whose signature could have significant
consequences for the observable universe.


title: Long velocity tails in plasmas and gravitational systems

abstract:
  Long tails in the velocity distribution are observed in plasmas and
gravitational systems. Some experiments and observations in
far-from-equilibrium conditions show that these tails behave as 1/v^(5/2). We
show here that such heavy tails are due to a universal mechanism related to the
fluctuations of the total force field. Owing to the divergence in 1/r^2 of the
binary interaction force, these fluctuations can be very large and their
probability density exhibits a similar long tail. They induce large velocity
fluctuations leading to the 1/v^(5/2) tail. We extract the mechanism causing
these properties from the BBGKY hierarchy representation of Statistical
Mechanics. This leads to a modification of the Vlasov equation by an additional
term. The novel term involves a fractional power 3/4 of the Laplacian in
velocity space and a fractional iterated time integral. Solving the new kinetic
equation for a uniform system, we retrieve the observed 1/v^(5/2) tail for the
velocity distribution. These results are confirmed by molecular dynamics
simulations.


title:
Pattern Formation in Chemically Interacting Active Rotors with
  Self-Propulsion

abstract:
  We demonstrate that active rotations in chemically signalling particles, such
as autochemotactic {\it E. coli} close to walls, create a route for pattern
formation based on a nonlinear yet deterministic instability mechanism. For
slow rotations, we find a transient persistence of the uniform state, followed
by a sudden formation of clusters contingent on locking of the average
propulsion direction by chemotaxis. These clusters coarsen, which results in
phase separation into a dense and a dilute region. Faster rotations arrest
phase separation leading to a global travelling wave of rotors with
synchronized roto-translational motion. Our results elucidate the physics
resulting from the competition of two generic paradigms in active matter,
chemotaxis and active rotations, and show that the latter provides a tool to
design programmable self-assembly of active matter, for example to control
coarsening.


title:
Extreme-value statistics from Lagrangian convex hull analysis for
  homogeneous turbulent Boussinesq convection and MHD convection

abstract:
  We investigate the utility of the convex hull of many Lagrangian tracers to
analyze transport properties of turbulent flows with different anisotropy. In
direct numerical simulations of statistically homogeneous and stationary
Navier-Stokes turbulence, neutral fluid Boussinesq convection, and MHD
Boussinesq convection a comparison with Lagrangian pair dispersion shows that
convex hull statistics capture the asymptotic dispersive behavior of a large
group of passive tracer particles. Moreover, convex hull analysis provides
additional information on the sub-ensemble of tracers that on average disperse
most efficiently in the form of extreme value statistics and flow anisotropy
via the geometric properties of the convex hulls. We use the convex hull
surface geometry to examine the anisotropy that occurs in turbulent convection.
Applying extreme value theory, we show that the maximal square extensions of
convex hull vertices are well described by a classic extreme value
distribution, the Gumbel distribution. During turbulent convection,
intermittent convective plumes grow and accelerate the dispersion of Lagrangian
tracers. Convex hull analysis yields information that supplements standard
Lagrangian analysis of coherent turbulent structures and their influence on the
global statistics of the flow.


title:
Homogenized model of immiscible incompressible two-phase flow in double
  porosity media : A new proof

abstract:
  In this paper we give a new proof of the homogenization result for an
immiscible incompressible two-phase flow in double porosity media obtained
earlier in the pioneer work by A. Bourgeat, S. Luckhaus, A. Mikeli\'c (1996)
and in the paper of L. M. Yeh (2006) under some restrictive assumptions. The
microscopic model consists of the usual equations derived from the mass
conservation laws for both fluids along with the standard Darcy-Muskat law
relating the velocities to the pressure gradients and gravitational effects.
The problem is written in terms of the phase formulation, i.e. where the phase
pressures and the phase saturations are primary unknowns. The fractured medium
consists of periodically repeating homogeneous blocks and fractures, where the
absolute permeability of the medium is discontinuous. The important difference
with respect to the results of the cited papers is that the global pressure
function as well as the saturation are also discontinuous. This makes the
initial mesoscopic problem more general and, physically, more realistic. The
convergence of the solutions, and the macroscopic models corresponding to
various range of contrast are constructed using the two-scale convergence
method combined with the dilation technique.


title: Pivotal Quantities with Arbitrary Small Skewness

abstract:
  In this paper we present randomization methods to enhance the accuracy of the
central limit theorem (CLT) based inferences about the population mean $\mu$.
We introduce a broad class of randomized versions of the Student $t$-statistic,
the classical pivot for $\mu$, that continue to possess the pivotal property
for $\mu$ and their skewness can be made arbitrarily small, for each fixed
sample size $n$. Consequently, these randomized pivots admit CLTs with smaller
errors. The randomization framework in this paper also provides an explicit
relation between the precision of the CLTs for the randomized pivots and the
volume of their associated confidence regions for the mean for both univariate
and multivariate data. This property allows regulating the trade-off between
the accuracy and the volume of the randomized confidence regions discussed in
this paper.


title:
Atomic-to-molecular gas phase transition triggered by the radio jet in
  Centaurus A

abstract:
  NGC 5128 (Centaurus A) is one of the best example to study AGN-feedback in
the local Universe. At 13.5 kpc from the galaxy, optical filaments with recent
star formation are lying along the radio-jet direction. We used the Atacama
Pathfinder EXperiment (APEX) to map the CO(2-1) emission all along the
filaments structure. Molecular gas mass of 8.2x10^7 Msun was found over the 4.2
kpc-structure which represents about 3% of the total gas mass of the NGC 5128
cold gas content. Two dusty mostly molecular structures are identified,
following the optical filaments. The region corresponds to the crossing of the
radio jet with the northern HI shell, coming from a past galaxy merger. One
filament is located at the border of the HI shell, while the other is entirely
molecular, and devoid of HI gas. The molecular mass is comparable to the HI
mass in the shell, suggesting a scenario where the atomic gas was shocked and
transformed in molecular clouds by the radio jet. Comparison with combined FIR
Herschel and UV GALEX estimation of star formation rates in the same regions
leads to depletion times of more than 10 Gyr. The filaments are thus less
efficient than discs in converting molecular gas into stars. Kinetic energy
injection triggered by shocks all along the jet/gas interface is a possible
process that appears to be consistent with MUSE line ratio diagnostics derived
in a smaller region of the northern filaments. Whether the AGN is the sole
origin of this energy input and what is the dominant (mechanical vs radiative)
mode for this process is however still to be investigated.


title: Universal corrections to entanglement entropy of local quantum quenches

abstract:
  We study the time evolution of single interval Renyi and entanglement
entropies following local quantum quenches in two dimensional conformal field
theories at finite temperature for which the locally excited states have a
finite temporal width, \epsilon. We show that, for local quenches produced by
the action of a conformal primary field, the time dependence of Renyi and
entanglement entropies at order \epsilon^2 is universal. It is determined by
the expectation value of the stress tensor in the replica geometry and
proportional to the conformal dimension of the primary field generating the
local excitation. We also show that in CFTs with a gravity dual, the \epsilon^2
correction to the holographic entanglement entropy following a local quench
precisely agrees with the CFT prediction. We then consider CFTs admitting a
higher spin symmetry and turn on a higher spin chemical potential \mu. We
calculate the time dependence of the order \epsilon^2 correction to the
entanglement entropy for small \mu, and show that the contribution at order
\mu^2 is universal. We verify our arguments against exact results for minimal
models and the free fermion theory.


title:
Minimizing The Expected Distortion Using Multi-layer Coding Approach In
  Two-Hop Networks

abstract:
  This work concerns minimizing the achievable distortion of a Gaussian source
over a two-hop block fading channel under mean square-error criterion. It is
assumed that there is not a direct link between transmission ends and the
communication is carried out through the use of a relay, employing the Decode
and Forward (DF) strategy. Moreover, for both of transmitter-to-relay and
relay-to-destination links the channel statistics are merely available at the
corresponding receivers, while the channel gains are not available at the
affiliated transmitters. It is assumed that a Gaussian source is hierarchically
encoded through the use of successive refinement source coding approach and
sent to the relay using a multi-layer channel code. Similarly, the relay
transmits the retrieved information to the destination through the use of a
multi-layer code. Accordingly, in a Rayleigh block fading environment, the
optimal power allocation across code layers is derived. Numerical results
demonstrate that the achievable distortion of the proposed multi-layer approach
outperforms that of single-layer code. Moreover, the resulting distortion of DF
strategy is better than Amplify and Forward~(AF) strategy for channel mismatch
factors greater than one, while the resulting distortion has a marginal
degradation for channel mismatch factors lower than one.


title: Ancilla-free Reversible Logic Synthesis via Sorting

abstract:
  Reversible logic synthesis is emerging as a major research component for
post-CMOS computing devices, in particular Quantum computing. In this work, we
link the reversible logic synthesis problem to sorting algorithms. Based on our
analysis, an alternative derivation of the worst-case complexity of generated
reversible circuits is provided. Furthermore, a novel column-wise reversible
logic synthesis method, termed RevCol, is designed with inspiration from radix
sort. Extending the principles of RevCol, we present a hybrid reversible logic
synthesis framework. The theoretical and experimental results are presented.
The results are extensively benchmarked with state-of-the-art ancilla-free
reversible logic synthesis methods.


title:
Performance Analysis of Joint Time Delay and Doppler-Stretch Estimation
  with Random Stepped-Frequency Signals

abstract:
  This paper investigates the performance of joint time delay and
Doppler-stretch estimation with the random stepp ed-frequency (RSF) signal.
Applying the ambiguity function (AF) to implement the estimation, we derive the
compact expressions of the theoretical mean square errors (MSEs) under high
signal-to-noise ratios (SNRs). The obtained MSEs are shown consistent with the
corresponding Cramer-Rao lower bounds (CRLBs), implying that the AF-based
estimation is approximately efficient. Waveform parameters including higher
carrier frequencies, wider bandwidth covered by the carrier frequencies, and
frequency shifting codewords with larger variance are expected for a better
estimation performance. As a synthetic wideband signal, the RSF signal achieves
the same estimation performance as the OFDM signal within an identical
bandwidth. Due to its instantaneous narrowband character, requirement for the
bandwidth of the receiver is much reduced.


title: Exponential Independence

abstract:
  For a set $S$ of vertices of a graph $G$, a vertex $u$ in $V(G)\setminus S$,
and a vertex $v$ in $S$, let ${\rm dist}_{(G,S)}(u,v)$ be the distance of $u$
and $v$ in the graph $G-(S\setminus \{ v\})$. Dankelmann et al. (Domination
with exponential decay, Discrete Math. 309 (2009) 5877-5883) define $S$ to be
an exponential dominating set of $G$ if $w_{(G,S)}(u)\geq 1$ for every vertex
$u$ in $V(G)\setminus S$, where $w_{(G,S)}(u)=\sum\limits_{v\in
S}\left(\frac{1}{2}\right)^{{\rm dist}_{(G,S)}(u,v)-1}$. Inspired by this
notion, we define $S$ to be an exponential independent set of $G$ if
$w_{(G,S\setminus \{ u\})}(u)<1$ for every vertex $u$ in $S$, and the
exponential independence number $\alpha_e(G)$ of $G$ as the maximum order of an
exponential independent set of $G$.
  Similarly as for exponential domination, the non-local nature of exponential
independence leads to many interesting effects and challenges. Our results
comprise exact values for special graphs as well as tight bounds and the
corresponding extremal graphs. Furthermore, we characterize all graphs $G$ for
which $\alpha_e(H)$ equals the independence number $\alpha(H)$ for every
induced subgraph $H$ of $G$, and we give an explicit characterization of all
trees $T$ with $\alpha_e(T)=\alpha(T)$.


title:
Generalized Galileons: instabilities of bouncing and Genesis cosmologies
  and modified Genesis

abstract:
  We study spatially flat bouncing cosmologies and models with the early-time
Genesis epoch in a popular class of generalized Galileon theories. We ask
whether there exist solutions of these types which are free of gradient and
ghost instabilities. We find that irrespectively of the forms of the Lagrangian
functions, the bouncing models either are plagued with these instabilities or
have singularities. The same result holds for the original Genesis model and
its variants in which the scale factor tends to a constant as $t\to -\infty$.
The result remains valid in theories with additional matter that obeys the Null
Energy Condition and interacts with the Galileon only gravitationally. We
propose a modified Genesis model which evades our no-go argument and give an
explicit example of healthy cosmology that connects the modified Genesis epoch
with kination (the epoch still driven by the Galileon field, which is a
conventional massless scalar field at that stage).


title:
An Equation of State For The TIP4P/2005 Model of Water Including
  Negative Pressures

abstract:
  One of the most promising frameworks for understanding the anomalies of cold
and especially supercooled water is that of two-structure thermodynamics, in
which water is viewed as a non-ideal mixture of two interconvertible local
structures. The non-ideality of this mixture may give rise, at very low
temperatures, to a liquid-liquid phase transition (LLPT) and a liquid-liquid
critical point (LLCP), at which thermodynamic response functions diverge.
Various versions of the "two-structure equation of state" (TSEOS) based on this
concept have shown remarkable agreement with both experimental data in real
water and simulation results. However, recent experiments probing supercooled
water at negative pressures reveal the inadequacy of extrapolations of
equations of state developed for positive pressures, and have begun to shed
additional light on the source of the anomalies of supercooled water. We have
analyzed simulation results for the TIP4P/2005 model over a broad range of
positive and negative pressures from ambient temperature to deep supercooling.
We find that by explicitly incorporating a liquid-vapor spinodal into a
two-structure equation of state, we are able to match the simulation data in
TIP4P/2005 with striking accuracy. In particular, our equation of state
reproduces the observed lines of minima and maxima in the density, isothermal
compressibility, and isobaric heat capacity. Contrary to scenarios in which a
retracing spinodal accounts for the thermodynamic anomalies of water, we find
that the liquid-vapor spinodal in this model continues monotonically to lower
pressures as temperature is decreased, influencing but not giving rise to the
locus of density maxima and other thermodynamic anomalies. We explain the
behavior of TIP4P/2005 in terms of two phenomena: the competition between two
local structures and a monotonic liquid-vapor spinodal.


title: On two questions by Finch and Jones about perfect order subset groups

abstract:
  A finite group G is said to be a POS-group if the number of elements of every
order occurring in G divides |G|. We answer two questions by Finch and Jones by
providing an infinite family of nonabelian POS-groups with orders not divisible
by 3.


title: The effective two-dimensional phase space of cosmological scalar fields

abstract:
  It has been shown by Remmen and Carroll that, for a model universe which
contains only a kinetically canonical scalar field minimally coupled to gravity
it is possible to choose 'special coordinates' to describe a two-dimensional
effective phase space. The special, non-canonical, coordinates are
$\phi$,$\dot{\phi}$ and the ability to describe an effective phase space with
these coordinates empowers the common usage of $\phi-\dot{\phi}$ as the space
to define inflationary initial conditions. This paper extends the result to the
full Horndeski action. The existence of a two-dimensional effective phase space
is shown for the general case. Subsets of the Horndeski action, relevant to
cosmology are considered as particular examples to highlight important aspects
of the procedure.


title: On the large deviations theorem of weaker types

abstract:
  In this paper, we introduce the concepts of the large deviations theorem of
weaker types, i.e., type I, type I', type II, type II', type III, and type
III', and present a systematic study of the ergodic and chaotic properties of
dynamical systems satisfying the large eviations theorem of various types. Some
characteristics of the ergodic measure are obtained and then applied to prove
that every dynamical system satisfying the large deviations theorem of type I'
is ergodic, which is equivalent to the large deviations theorem of type II' in
this regard, and that every uniquely ergodic dynamical system restricted on its
support satisfies the large deviations theorem. Moreover, we prove that every
dynamical system satisfying the large deviations theorem of type III is an
$E$-system. Finally, we show that a dynamical system satisfying the central
limit theorem, introduced in [Y. Niu, Y. Wang, Statist. Probab. Lett., {\bf 80}
(2010), 1180--1184], does not exist.


title: Competing covalent and ionic bonding in Ge-Sb-Te phase change materials

abstract:
  Ge2Sb2Te5 and related phase change materials are highly unusual in that they
can be readily transformed between amorphous and crystalline states using very
fast melt, quench, anneal cycles, although the resulting states are extremely
long lived at ambient temperature. These states have remarkably different
physical properties including very different optical constants in the visible
in strong contrast to common glass formers such as silicates or phosphates.
This behavior has been described in terms of resonant bonding, but puzzles
remain, particularly regarding different physical properties of crystalline and
amorphous phases. Here we show that there is a strong competition between ionic
and covalent bonding in cubic phase providing a link between the chemical basis
of phase change memory property and origins of giant responses of piezoelectric
materials (PbTiO3, BiFeO3). This has important consequences for dynamical
behavior in particular leading to a simultaneous hardening of acoustic modes
and softening of high frequency optic modes in crystalline phase relative to
amorphous. This different bonding in amorphous and crystalline phases provides
a direct explanation for different physical properties and understanding of the
combination of long time stability and rapid switching and may be useful in
finding new phase change compositions with superior properties.


title: Magnetic Domain Wall Engineering in a Nanoscale Permalloy Junction

abstract:
  Nanoscale magnetic junction provides a useful approach to act as the building
block for magnetoresistive random access memories (MRAM), where one of the key
issues is to control the magnetic domain configuration. Here, we study the
domain structure and the magnetic switching in the Permalloy (Fe20Ni80)
nanoscale magnetic junctions with different thicknesses by using micromagnetic
simulations. It is found that both the 90-degree and 45-degree domain walls can
be formed between the junctions and the wire arms depending on the thickness of
the device. The magnetic switching fields show distinct thickness dependencies
with a broad peak varying from 7 nm to 22 nm depending on the junction sizes,
and the large magnetic switching fields favor the stability of the MRAM
operation.


title: Thermal geometry from CFT at finite temperature

abstract:
  We present how the thermal geometry emerges from CFT at finite temperature by
using the truncated entanglement renormalization network, the cMERA. For the
case of $2d$ CFT, the reduced geometry is the BTZ black hole or the thermal AdS
as expectation. In order to determine which spacetimes prefer to form, we
propose a cMERA description of the Hawking-Page phase transition. Our proposal
is in agreement with the picture of the recent proposed surface/state
correspondence.