title: Integral of radical trigonometric functions revisited

abstract:
  This article revisits an integral of radical trigonometric functions. It
presents several methods of integration where the integrand takes the form
$\sqrt{1 \pm \sin x}$ or $\sqrt{1 \pm \cos x}$. The integral has applications
in Calculus where it appears as the length of cardioid represented in polar
coordinates.


title: A H-ARQ scheme for polar codes

abstract:
  We consider the problem of supporting H-ARQ with polar codes. For supporting
H-ARQ, we propose to create redundancy versions based on different, but
equivalent, subsets of a polar code. The equivalent subsets are created from an
initial subset of a polar code using an inherent symmetry in polar code
construction. A greedy construction is used to create the initial subset of a
polar code. We demonstrate performance of proposed constructions via
simulations for binary input AWGN channel. We demonstrate that a (4096, 1024)
polar code can be divided into two disjoint (2048, 1024) subset polar codes,
which when decoded individually are within 0.2 dB (at $1 \%$ BLER) of a (2048,
1024) polar code, and achieve performance of a (4096, 1024) polar code when
decoded jointly.


title:
Two-phase forward solutions for one-dimensional forward-backward
  parabolic equations with linear convection and reaction

abstract:
  We study the existence and properties of Lipschitz continuous weak solutions
to the Neumann boundary value problem for a class of one-dimensional
quasilinear forward-backward diffusion equations with linear convection and
reaction. The diffusion flux function is assumed to be of a forward-backward
type that contains two forward-diffusion phases. We prove that, for all smooth
initial data, there exists at least one weak solution whose spatial derivative
stays in the two forward phases. Also, for all smooth initial data that have a
derivative value lying in a certain phase transition range, we show that there
exist infinitely many such solutions that exhibit instantaneous phase
transitions between the two forward phases. Moreover, we introduce the notion
of transition gauge for such forward solutions and prove that the gauge of all
constructed two-phase forward solutions can be arbitrarily close to a certain
fixed constant.


title:
Microscopic derivation of the Bohr-Mottelson collective Hamiltonian and
  its application to quadrupole shape dynamics

abstract:
  We discuss the nature of the low-frequency quadrupole vibrations from
small-amplitude to large-amplitude regimes. We consider full five-dimensional
quadrupole dynamics including three-dimensional rotations restoring the broken
symmetries as well as axially symmetric and asymmetric shape fluctuations.
Assuming that the time-evolution of the self-consistent mean field is
determined by five pairs of collective coordinates and collective momenta, we
microscopically derive the collective Hamiltonian of Bohr and Mottelson, which
describes low-frequency quadrupole dynamics. We show that the five-dimensional
collective Schr\"odinger equation is capable of describing large-amplitude
quadrupole shape dynamics seen as shape coexistence/mixing phenomena. We
summarize the modern concepts of microscopic theory of large-amplitude
collective motion, which is underlying the microscopic derivation of the
Bohr-Mottelson collective Hamiltonian.


title:
Detecting intermediate mass black holes in globular clusters with
  machine learning

abstract:
  Mergers of stellar-mass black holes were recently observed in the
gravitational wave window opened by LIGO. This puts the spotlight on dense
stellar systems and their ability to create intermediate-mass black holes
(IMBHs) through repeated merging. Unfortunately, attempts at direct and
indirect IMBH detection in star clusters in the nearby universe have proven
inconclusive as of now. Indirect detection methods attempt to constrain IMBHs
through their effect on star cluster photometric and kinematic observables.
They are usually based on looking for a specific, physically motivated
signature. While this approach is justified, it may be suboptimal in its usage
of the available data. Here I present a new indirect detection method, based on
machine learning, that is unaffected by these restrictions. I reduce the
scientific question whether a star cluster hosts an IMBH to a classification
problem in the machine learning framework. I present preliminary results to
illustrate how machine learning models are trained on simulated datasets and
measure their performance on previously unseen, simulated data.


title: Automatic Variational ABC

abstract:
  Approximate Bayesian Computation (ABC) is a framework for performing
likelihood-free posterior inference for simulation models. Stochastic
Variational inference (SVI) is an appealing alternative to the inefficient
sampling approaches commonly used in ABC. However, SVI is highly sensitive to
the variance of the gradient estimators, and this problem is exacerbated by
approximating the likelihood. We draw upon recent advances in variance
reduction for SV and likelihood-free inference using deterministic simulations
to produce low variance gradient estimators of the variational lower-bound. By
then exploiting automatic differentiation libraries we can avoid nearly all
model-specific derivations. We demonstrate performance on three problems and
compare to existing SVI algorithms. Our results demonstrate the correctness and
efficiency of our algorithm.


title:
Ultrafast, high repetition rate, ultraviolet, fiber based laser source:
  application towards Yb+ fast quantum-logic

abstract:
  Trapped ions are one of the most promising approaches for the realization of
a universal quantum computer. Faster quantum logic gates could dramatically
improve the performance of trapped-ion quantum computers, and require the
development of suitable high repetition rate pulsed lasers. Here we report on a
robust frequency upconverted fiber laser based source, able to deliver 2.5 ps
ultraviolet (UV) pulses at a stabilized repetition rate of 300.00000 MHz with
an average power of 190 mW. The laser wavelength is resonant with the strong
transition in Ytterbium (Yb+) at 369.53 nm and its repetition rate can be
scaled up using high harmonic mode locking. We show that our source can produce
arbitrary pulse patterns using a programmable pulse pattern generator and fast
modulating components. Finally, simulations demonstrate that our laser is
capable of performing resonant, temperature-insensitive, two-qubit quantum
logic gates on trapped Yb$^+$ ions faster than the trap period and with
fidelity above 99%.


title:
Time-reversing a monochromatic subwavelength optical focus by optical
  phase conjugation of multiply-scattered light

abstract:
  Due to its time-reversal nature, optical phase conjugation generates a
monochromatic light wave which retraces its propagation paths. Here, we
demonstrate the regeneration of a subwavelength optical focus by phase
conjugation. Monochromatic light from a subwavelength source is scattered by
random nanoparticles, and the scattered light is phase conjugated at the
far-field region by coupling its wavefront into a single-mode optical reflector
using a spatial light modulator. Then the conjugated beam retraces its
propagation paths and forms a refocus on the source at the subwavelength scale.
This is the first direct experimental realization of subwavelength focusing
beyond the diffraction limit with far-field time reversal in the optical
domain.


title: Dual wavefunction of the Felderhof model

abstract:
  We study the Felderhof free-fermion six-vertex model, whose wavefunction
recently turned out to possess rich combinatorial structure of the Schur
polynomials. We investigate the dual version of the wavefunction in this paper,
which seems to be a harder object to analyze. We evaluate the dual wavefunction
in two ways. First, we give the exact correspondence between the dual
wavefunction and the Schur polynomials, for which two proofs are given. Next,
we make a microscopic analysis and express the dual wavefunction in terms of
strict Gelfand-Tsetlin pattern. As a consequence of these two ways of
evaluation of the dual wavefunction, we obtain a dual version of the Tokuyama
combinatorial formula for the Schur polynomials. We also give a generalization
of the correspondence between the dual wavefunction of the Felderhof model and
the factorial Schur polynomials.


title:
A combined spectroscopic and photometric stellar activity study of
  Epsilon Eridani

abstract:
  We present simultaneous ground-based radial velocity (RV) measurements and
space-based photometric measurements of the young and active K dwarf Epsilon
Eridani. These measurements provide a data set for exploring methods of
identifying and ultimately distinguishing stellar photospheric velocities from
Keplerian motion. We compare three methods we have used in exploring this data
set: Dalmatian, an MCMC spot modeling code that fits photometric and RV
measurements simultaneously; the FF$'$ method, which uses photometric
measurements to predict the stellar activity signal in simultaneous RV
measurements; and H$\alpha$ analysis. We show that our H$\alpha$ measurements
are strongly correlated with photometry from the Microvariability and
Oscillations of STars (MOST) instrument, which led to a promising new method
based solely on the spectroscopic observations. This new method, which we refer
to as the HH$'$ method, uses H$\alpha$ measurements as input into the FF$'$
model. While the Dalmatian spot modeling analysis and the FF$'$ method with
MOST space-based photometry are currently more robust, the HH$'$ method only
makes use of one of the thousands of stellar lines in the visible spectrum. By
leveraging additional spectral activity indicators, we believe the HH$'$ method
may prove quite useful in disentangling stellar signals.


title:
Factorization in XYZ spin systems under general fields and separable
  ground state engineering

abstract:
  We discuss ground state factorization schemes in spin $S$ arrays with general
$XYZ$ couplings under general magnetic fields, not necessarily uniform or
transverse. It is first shown that given arbitrary spin alignment directions at
each site, nonzero couplings between any pair and fields at each site always
exist such that the ensuing Hamiltonian has an exactly separable eigenstate
with the spins pointing along the specified directions. Furthermore, by
suitable tuning of the fields this eigenstate can always be cooled down to a
nondegenerate ground state. It is also shown that in open one-dimensional
systems with arbitrary $XYZ$ first neighbor couplings, at least one separable
eigenstate compatible with an arbitrarily chosen spin direction at one site is
always feasible if the fields at each site can be tuned. We demonstrate as well
that in the vicinity of factorization, i.e., for small perturbations in the
fields or couplings, pairwise entanglement reaches full range. Some noticeable
examples of factorized eigenstates for uniform couplings are unveiled. The
present results open the way for separable ground state engineering. A notation
to quantify the complexity of a given type of solution according to the
required control on the system couplings and fields is introduced.


title: Strength of Cu-TiN and Al-TiN interfaces from first-principles

abstract:
  Using density functional theory (DFT) based first principles calculations, we
show that the preferred interfacial plane orientation relationship is
determined by the strength of bonding at the interface. The thermodynamic
stability, and the ideal tensile and shear strengths of Cu/TiN and Al/TiN
interfaces are calculated. While there is a strong orientation relation (OR)
preference for Al/TiN interface, there is no OR preference for Cu/TiN
interface. Both the ideal tensile and shear strengths of Cu/TiN interfaces are
lower than those of bulk Cu and TiN, suggesting such interfaces are weaker than
their bulk components. By comparison, the ideal strengths of Al/TiN interface
are comparable to the constituents in the bulk form. Such contrasting
interfaces can be a test-bed for studying the role of interfaces in determining
the mechanical behavior of the nanolayered structures.


title:
Thermal Relaxation, Electrical Conductivity and Charge Diffusion in a
  Hot QCD Medium

abstract:
  The response of electromagnetic (EM) fields that are produced in non-central
heavy-ion collisions to electromagnetically charged quark gluon plasma can be
understood in terms of charge transport and charge diffusion in the hot QCD
medium. This article presents a perspective on these processes by investigating
the temperature behavior of the related transport coefficients, {\it viz.}
electrical conductivity and the charge diffusion coefficients along with charge
susceptibility. In the process of estimating them, thermal relaxation times for
quarks and gluons have been determined first. These transport coefficients have
been studied by solving the relativistic transport equation in the
Chapman-Enskog method. For the analysis, $2\rightarrow 2$, quark-quark,
quark-gluon and gluon-gluon scattering processes are taken into account along
with an effective description of hot QCD Equations of state (EOSs) in terms of
temperature dependent effective fugacities of quasi-quarks (anti-quarks) and
quasi-gluons. Both improved perturbative hot QCD EOSs at high temperature and a
lattice QCD EOS are included for the analysis. The hot QCD medium effects
entering through the quasi-particle momentum distributions along with an
effective coupling, are seen to have significant impact on the temperature
behavior of these transport parameters along with the thermal relaxation times
for the quasi-gluons and quasi-quarks


title:
Reconstruction Error Bounds for Compressed Sensing under Poisson Noise
  using the Square Root of the Jensen-Shannon Divergence

abstract:
  Reconstruction error bounds in compressed sensing under Gaussian or uniform
bounded noise do not translate easily to the case of Poisson noise. Reasons for
this include the signal dependent nature of Poisson noise, and also the fact
that the negative log likelihood (NLL) in case of a Poisson distribution (which
is related to the generalized Kullback-Leibler divergence (GKLD)) is not a
metric and does not obey the triangle inequality. There exist prior theoretical
results in the form of provable error bounds for computationally tractable
estimators for compressed sensing problems under Poisson noise. However, these
results do not apply to realistic compressive systems, which must obey some
crucial constraints such as non-negativity and flux preservation. On the other
hand, there exist provable error bounds for such realistic systems in the
published literature, but they are for estimators that are computationally
intractable. In this paper, we develop error bounds for a computationally
tractable estimator which also applies to realistic compressive systems obeying
the required constraints. Our technique replaces the GKLD, with an information
theoretic metric - namely the square root of the Jensen-Shannon divergence
(JSD), which is related to an approximate, symmetrized version of the Poisson
NLL. We show that this allows for simple proofs of the error bounds. We propose
and prove interesting statistical properties of the square root of JSD and
exploit other known ones. Numerical experiments are performed showing the use
of the technique in signal and image reconstruction from compressed
measurements under Poisson noise. Our technique applies to sparse/ compressible
signals in any orthonormal basis, works with high probability for any randomly
generated non-negative and flux-preserving sensing matrix and is proposes an
estimator whose parameters are purely statistically motivated.


title:
Raman spectroscopic signature of fractionalized excitations in the
  harmonic-honeycomb iridates $\beta$- and $\gamma$-Li$_2$IrO$_3$

abstract:
  The fractionalization of elementary excitations in quantum spin systems is a
central theme in current condensed matter physics. The Kitaev honeycomb spin
model provides a prominent example of exotic fractionalized quasiparticles,
composed of itinerant Majorana fermions and gapped gauge fluxes. However,
identification of the Majorana fermions in a three-dimensional honeycomb
lattice remains elusive. Here we report spectroscopic signatures of fractional
excitations in the harmonic-honeycomb iridates $\beta$- and
$\gamma$-Li$_2$IrO$_3$. Using polarization resolved Raman spectroscopy, we find
that the dynamical Raman response of $\beta$- and $\gamma$-Li$_2$IrO$_3$
features a broad scattering continuum with distinct polarization and
composition dependence. The temperature dependence of the Raman spectral weight
is dominated by the thermal damping of fermionic excitations. These results
suggest the emergence of Majorana fermions from spin fractionalization in a
three-dimensional Kitaev-Heisenberg system.


title:
Limit of zT enhancement in rock-salt structured chalcogenides by band
  convergence?

abstract:
  Rock-salt structured chalcogenides, such as PbTe, PbSe, and SnTe, are the top
candidates for mid-temperature thermoelectric applications, and their p-type
thermoelectric efficiencies can be enhanced via aligning the valence bands.
Here, we provided comprehensive numerical investigations on the effects of band
convergence on electronic properties. We found that the extra valance band can
indeed significantly enhance the power factor. Nevertheless, the extra valance
band can also increase the electronic thermal conductivity, which partially
offsets the enhanced power factor for the overall figure-of-merit. Finally, we
predicted that the maximum figure-of-merit for PbTe, PbSe, and SnTe can reach
to 2.2, 1.8, and 1.6, re-spectively, without relying on the reduction in
lattice thermal conductivity.


title: Orbital order from the on-site orbital attraction

abstract:
  We study the model of Fe-based superconductors with intraorbital attraction,
designed to favor a spontaneous orbital polarization. Previous studies of this
model within the two-orbital approximation indicated that the leading
instability is toward s-wave superconductivity and the subleading one is toward
anti-ferro-orbital order, which breaks the translational symmetry of the
crystal. The two-orbital approximation is, however, not consistent with the
Fermi surface geometry of Fe superconductors, as it yields the wrong position
of one of the hole pockets. Here we analyze the model with the same interaction
but with realistic Fermi surface geometry (two hole pockets at the center of
the Brillouin zone and two electron pockets at its boundary). We apply the
parquet renormalization-group (pRG) technique to detect the leading instability
upon the lowering of the temperature. We argue that the pRG analysis strongly
favors a q = 0 orbital order, which in the band basis is a d-wave Pomeranchuk
order.


title:
Estimating the class prior and posterior from noisy positives and
  unlabeled data

abstract:
  We develop a classification algorithm for estimating posterior distributions
from positive-unlabeled data, that is robust to noise in the positive labels
and effective for high-dimensional data. In recent years, several algorithms
have been proposed to learn from positive-unlabeled data; however, many of
these contributions remain theoretical, performing poorly on real
high-dimensional data that is typically contaminated with noise. We build on
this previous work to develop two practical classification algorithms that
explicitly model the noise in the positive labels and utilize univariate
transforms built on discriminative classifiers. We prove that these univariate
transforms preserve the class prior, enabling estimation in the univariate
space and avoiding kernel density estimation for high-dimensional data. The
theoretical development and both parametric and nonparametric algorithms
proposed here constitutes an important step towards wide-spread use of robust
classification algorithms for positive-unlabeled data.


title:
Complex Systems and a Computational Social Science Perspective on the
  Labor Market

abstract:
  Labor market institutions are central for modern economies, and their polices
can directly affect unemployment rates and economic growth. At the individual
level, unemployment often has a detrimental impact on people's well-being and
health. At the national level, high employment is one of the central goals of
any economic policy, due to its close association with national prosperity. The
main goal of this thesis is to highlight the need for frameworks that take into
account the complex structure of labor market interactions. In particular, we
explore the benefits of leveraging tools from computational social science,
network science, and data-driven theories to measure the flow of opportunities
and information in the context of the labor market. First, we investigate our
key hypothesis, which is that opportunity/information flow through weak ties,
and this is a key determinant of the length of unemployment. We then extend the
idea of opportunity/information flow to clusters of other economic activities,
where we expect the flow within clusters of related activities to be higher
than within isolated activities. This captures the intuition that within
related activities there are more "capitals" involved and that such activities
require similar "capabilities." Therefore, more extensive clusters of economic
activities should generate greater growth through exploiting the greater flow
of opportunities and information. We quantify the opportunity/information flow
using a complexity measure of two economic activities (i.e. jobs and exports).


title:
Nonsymmorphic Weyl superconductivity in UPt_3 based on E_2u
  representation

abstract:
  We show that a heavy fermion superconductor UPt_3 is a topological Weyl
superconductor with tunable Weyl nodes. Adopting a generic order parameter in
the E_2u representation allowed by nonsymmorphic crystal symmetry, we clarify
unusual gap structure and associated topological properties. The pair creation,
pair annihilation, and coalescence of Weyl nodes are demonstrated in the
time-reversal symmetry broken B-phase. At most 98 point nodes compatible with
Blount's theorem give rise to line node-like behaviors in low-energy
excitations, consistent with experimental results. We also show an arc node
protected by the nonsymmorphic crystal symmetry on the Brillouin zone face.


title:
Velocity shear, turbulent saturation, and steep plasma gradients in the
  scrape-off layer of inner-wall limited tokamaks

abstract:
  The narrow power decay-length ($\lambda_q$), recently found in the scrape-off
layer (SOL) of inner-wall limited (IWL) discharges in tokamaks, is studied
using 3D, flux-driven, global two-fluid turbulence simulations. The formation
of the steep plasma profiles measured is found to arise due to radially sheared
$\vec{E}\times\vec{B}$ poloidal flows. A complex interaction between sheared
flows and outflowing plasma currents regulates the turbulent saturation,
determining the transport levels. We quantify the effects of sheared flows,
obtaining theoretical estimates in agreement with our non-linear simulations.
Analytical calculations suggest that the IWL $\lambda_q$ is roughly equal to
the turbulent correlation length.


title:
Warped Graviton Couplings to Bulk Vectors with Brane Localised Kinetic
  Terms

abstract:
  We realize non-universal couplings between Kaluza-Klein (KK) gravitons and
bulk Standard Model (SM) vectors in the Randall-Sundrum (RS) model by including
both UV and IR brane-localised gauge kinetic terms. We find that such kinetic
terms can reduce the couplings of KK gravitons to SM gauge bosons and also
ensure the KK vector masses are consistent with electroweak precision
constraints.


title:
Metallic monoclinic phase in VO$_2$ induced by electrochemical gating:
  in-situ Raman study

abstract:
  We report in-situ Raman scattering studies of electrochemically top gated
VO$_2$ thin film to address metal-insulator transition (MIT) under gating. The
room temperature monoclinic insulating phase goes to metallic state at a gate
voltage of 2.6 V. However, the number of Raman modes do not change with
electrolyte gating showing that the metallic phase is still monoclinic. The
high frequency Raman mode A$_g$(7) near 616 cm$^{-1}$ ascribed to V-O vibration
of bond length 2.06 \AA~ in VO$_6$ octahedra hardens with increasing gate
voltage and the B$_g$(3) mode near 654 cm$^{-1}$ softens. This shows that the
distortion of the VO$_6$ octahedra in the monoclinic phase decreases with
gating. The time dependent Raman data at fixed gate voltages of 1 V (for 50
minute, showing enhancement of conductivity by a factor of 50) and 2 V (for 130
minute, showing further increase in conductivity by a factor of 5) show similar
changes in high frequency Raman modes A$_g$(7) and B$_g$(3) as observed in
gating. This slow change in conductance together with Raman frequency changes
show that the governing mechanism for metalization is more likely to the
diffusion controlled oxygen vacancy formation due to the applied electric
field.


title: On the mathematical consequences of binning spike trains

abstract:
  We initiate a mathematical analysis of hidden effects induced by binning
spike trains of neurons. Assuming that the original spike train has been
generated by a discrete Markov process, we show that binning generates a
stochastic process which is not Markov any more, but is instead a Variable
Length Markov Chain (VLMC) with unbounded memory. We also show that the law of
the binned raster is a Gibbs measure in the DLR (Dobrushin-Lanford-Ruelle)
sense coined in mathematical statistical mechanics. This allows the derivation
of several important consequences on statistical properties of binned spike
trains. In particular, we introduce the DLR framework as a natural setting to
mathematically formalize anticipation, i.e. to tell "how good" our nervous
system is at making predictions. In a probabilistic sense, this corresponds to
condition a process by its future and we discuss how binning may affect our
conclusions on this ability. We finally comment what could be the consequences
of binning in the detection of spurious phase transitions or in the detection
of wrong evidences of criticality.


title:
First-principles description of van der Waals-bonded spin-polarized
  systems using vdW-DF$+U$ method---application to solid oxygen at low pressure

abstract:
  The description of the molecular solid phase of O$_2$, especially its
ground-state antiferromagnetic insulating phase, is known to be quite
unsatisfactory within the conventional local and semilocal density functional
approximations used in the Kohn-Sham formalism of density functional theory.
The recently-developed van der Waals functionals that take into account
nonlocal correlations have also shown subpar performance in this regard. The
difficulty lies in the subtle balance between the van der Waals interactions
and the exchange coupling between the antiferromagnetic and ferromagnetic
molecule pairs in the molecular crystal. Here, we report that the DFT$+U$
approach used in combination with the vdW-DF functional performs surprisingly
well in this regard, and discuss the reasoning behind this behavior. We also
apply this approach to study the recently-reported magnetic field-induced
$\theta$ phase of solid O$_2$.


title: Horndeski black hole observational properties

abstract:
  We examine geodesics for scalar-tensor black holes in the Horndeski-Galileon
non-minimal kinetic coupling framework. Our analysis shows that bound orbits
may not be present within some model parameters range. Using the observational
data we pose bounds on possible solution parameter values, as well as initial
model parameters.


title:
Pseudospin symmetry in nuclear structure and its supersymmetric
  representation

abstract:
  The quasi-degeneracy between the single-particle states $(n,\,l,\,j=l+1/2)$
and $(n-1,\,l+2,\,j=l+3/2)$ indicates a special and hidden symmetry in atomic
nuclei---the so-called pseudospin symmetry (PSS)---which is an important
concept in both spherical and deformed nuclei. A number of phenomena in nuclear
structure have been successfully interpreted directly or implicitly by this
symmetry, including nuclear superdeformed configurations, identical bands,
quantized alignment, pseudospin partner bands, and so on. Since the PSS was
recognized as a relativistic symmetry in 1990s, there have been comprehensive
efforts to understand its properties in various systems and potentials. In this
Review, we mainly focus on the latest progress on the supersymmetric (SUSY)
representation of PSS, and one of the key targets is to understand its
symmetry-breaking mechanism in realistic nuclei in a quantitative and
perturbative way. The SUSY quantum mechanics and its applications to the SU(2)
and U(3) symmetries of the Dirac Hamiltonian are discussed in detail. It is
shown that the origin of PSS and its symmetry-breaking mechanism, which are
deeply hidden in the origin Hamiltonian, can be traced by its SUSY partner
Hamiltonian. Essential open questions, such as the SUSY representation of PSS
in the deformed system, are pointed out.


title: Alternating Back-Propagation for Generator Network

abstract:
  This paper proposes an alternating back-propagation algorithm for learning
the generator network model. The model is a non-linear generalization of factor
analysis. In this model, the mapping from the continuous latent factors to the
observed signal is parametrized by a convolutional neural network. The
alternating back-propagation algorithm iterates the following two steps: (1)
Inferential back-propagation, which infers the latent factors by Langevin
dynamics or gradient descent. (2) Learning back-propagation, which updates the
parameters given the inferred latent factors by gradient descent. The gradient
computations in both steps are powered by back-propagation, and they share most
of their code in common. We show that the alternating back-propagation
algorithm can learn realistic generator models of natural images, video
sequences, and sounds. Moreover, it can also be used to learn from incomplete
or indirect training data.


title:
Diversified Visual Attention Networks for Fine-Grained Object
  Classification

abstract:
  Fine-grained object classification is a challenging task due to the subtle
inter-class difference and large intra-class variation. Recently, visual
attention models have been applied to automatically localize the discriminative
regions of an image for better capturing critical difference and demonstrated
promising performance. However, without consideration of the diversity in
attention process, most of existing attention models perform poorly in
classifying fine-grained objects. In this paper, we propose a diversified
visual attention network (DVAN) to address the problems of fine-grained object
classification, which substan- tially relieves the dependency on
strongly-supervised information for learning to localize discriminative regions
compared with attentionless models. More importantly, DVAN explicitly pursues
the diversity of attention and is able to gather discriminative information to
the maximal extent. Multiple attention canvases are generated to extract
convolutional features for attention. An LSTM recurrent unit is employed to
learn the attentiveness and discrimination of attention canvases. The proposed
DVAN has the ability to attend the object from coarse to fine granularity, and
a dynamic internal representation for classification is built up by
incrementally combining the information from different locations and scales of
the image. Extensive experiments con- ducted on CUB-2011, Stanford Dogs and
Stanford Cars datasets have demonstrated that the proposed diversified visual
attention networks achieve competitive performance compared to the state-
of-the-art approaches, without using any prior knowledge, user interaction or
external resource in training or testing.


title:
The GW plus cumulant method and plasmonic polarons: application to the
  homogeneous electron gas

abstract:
  We study the spectral function of the homogeneous electron gas using
many-body perturbation theory and the cumulant expansion. We compute the
angle-resolved spectral function based on the GW approximation and the `GW plus
cumulant' approach. In agreement with previous studies, the GW spectral
function exhibits a spurious plasmaron peak at energies 1.5$\omega_{\rm pl}$
below the quasiparticle peak, $\omega_{\rm pl}$ being the plasma energy. The GW
plus cumulant approach, on the other hand, reduces significantly the intensity
of the plasmon-induced spectral features and renormalizes their energy relative
to the quasiparticle energy to $\omega_{\rm pl}$. Consistently with previous
work on semiconductors, our results show that the HEG is characterized by the
emergence of plasmonic polaron bands, that is, broadened replica of the
quasiparticle bands, red-shifted by the plasmon energy.


title:
Decoherence of high-energy electrons in weakly disordered quantum Hall
  edge states

abstract:
  We investigate theoretically the phase coherence of electron transport in
edge states of the integer quantum Hall effect at filling factor $\nu=2$, in
the presence of disorder and inter-edge state Coulomb interaction. Within a
Fokker-Planck approach, we calculate analytically the visibility of the
Aharonov-Bohm oscillations of the current through an electronic Mach-Zehnder
interferometer. In agreement with recent experiments, we find that the
visibility is independent of the energy of the current-carrying electrons
injected high above the Fermi sea. Instead, it is the amount of disorder at the
edge that sets the phase space available for inter-edge state energy exchange
and thereby controls the visibility suppression.


title:
Charge-changing-cross-section measurements of $^{12-16}$C at around
  $45A$ MeV and development of a Glauber model for incident energies
  $10A-2100A$ MeV

abstract:
  We have measured for the first time the charge-changing cross sections
($\sigma_{\text{CC}}$) of $^{12-16}$C on a $^{12}$C target at energies below
$100A$ MeV. To analyze these low-energy data, we have developed a finite-range
Glauber model with a global parameter set within the optical-limit
approximation which is applicable to reaction cross section
($\sigma_{\text{R}}$) and $\sigma_{\text{CC}}$ measurements at incident
energies from 10$A$ to $2100A$ MeV. Adopting the proton-density distribution of
$^{12}$C known from the electron-scattering data, as well as the bare total
nucleon-nucleon cross sections, and the real-to-imaginary-part ratios of the
forward proton-proton elastic scattering amplitude available in the
literatures, we determine the energy-dependent slope parameter $\beta_{\rm pn}$
of the proton-neutron elastic differential cross section so as to reproduce the
existing $\sigma_{\text{R}}$ and interaction-cross-section data for
$^{12}$C+$^{12}$C over a wide range of incident energies. The Glauber model
thus formulated is applied to calculate the $\sigma_{\text{\tiny R}}$'s of
$^{12}$C on a $^9$Be and $^{27}$Al targets at various incident energies. Our
calculations show excellent agreement with the experimental data. Applying our
model to the $\sigma_{\text{\tiny R}}$ and $\sigma_{\text{\tiny CC}}$ for the
"neutron-skin" $^{16}$C nucleus, we reconfirm the importance of measurements at
incident energies below $100A$ MeV. The proton root-mean-square radii of
$^{12-16}$C are extracted using the measured $\sigma_{\text{CC}}$'s and the
existing $\sigma_{\text{R}}$ data. The results for $^{12-14}$C are consistent
with the values from the electron scatterings, demonstrating the feasibility,
usefulness of the $\sigma_{\text{CC}}$ measurement and the present Glauber
model.


title:
Observation of quantum Hall effect in a microstrained Bi$_2$Se$_3$
  single crystal

abstract:
  We report the observation of quantum Hall effect (QHE) in a Bi$_2$Se$_3$
single crystal having carrier concentration ($n$)
$\sim1.13\times10^{19}$cm$^{-3}$, three dimensional Fermi surface and bulk
transport characteristics. The plateaus in Hall resistivity coincide with
minima of Shubnikov de Haas oscillations in resistivity. Our results
demonstrate that the presence of perfect two dimensional transport is not an
essential condition for QHE in Bi$_2$Se$_3$. The results of high resolution
x-ray diffraction (HRXRD), energy-dispersive x-ray spectroscopy (EDX), and
residual resistivity measurements show the presence of enhanced crystalline
defects and microstrain. We propose that the formation of localized state at
the edge of each Landau level due to resonance between the bulk and defect band
of Bi$_2$Se$_3$ causes the quantum Hall effect.


title:
Reliability analysis of high-dimensional models using low-rank tensor
  approximations

abstract:
  Engineering and applied sciences use models of increasing complexity to
simulate the behaviour of manufactured and physical systems. Propagation of
uncertainties from the input to a response quantity of interest through such
models may become intractable in cases when a single simulation is time
demanding. Particularly challenging is the reliability analysis of systems
represented by computationally costly models, because of the large number of
model evaluations that are typically required to estimate small probabilities
of failure. In this paper, we demonstrate the potential of a newly emerged
meta-modelling technique known as low-rank tensor approximations to address
this limitation. This technique is especially promising for high-dimensional
problems because: (i) the number of unknowns in the generic functional form of
the meta-model grows only linearly with the input dimension and (ii) such
approximations can be constructed by relying on a series of minimization
problems of small size independent of the input dimension. In example
applications involving finite-element models pertinent to structural mechanics
and heat conduction, low-rank tensor approximations built with polynomial bases
are found to outperform the popular sparse polynomial chaos expansions in the
estimation of tail probabilities when small experimental designs are used. It
should be emphasized that contrary to methods particularly targeted to
reliability analysis, the meta-modelling approach also provides a full
probabilistic description of the model response, which can be used to estimate
any statistical measure of interest.


title: Experimental noiseless linear amplification using weak measurements

abstract:
  The viability of quantum communication schemes rely on sending quantum states
of light over long distances. However, transmission loss can degrade the signal
strength, adding noise. Heralded noiseless amplification of a quantum signal
can provide a solution by enabling longer direct transmission distances and by
enabling entanglement distillation. The central idea of heralded noiseless
amplification---a conditional modification of the probability distribution over
photon number of an optical quantum state---is suggestive of a parallel with
weak measurement: in a weak measurement, learning partial information about an
observable leads to a conditional back-action of a commensurate size. Here we
experimentally investigate the application of weak, or variable-strength,
measurements to the task of heralded amplification, by using a quantum logic
gate to weakly couple a small single-optical-mode quantum state (the signal) to
an ancilla photon (the meter). The weak measurement is carried out by choosing
the measurement basis of the meter photon and, by conditioning on the meter
outcomes, the signal is amplified. We characterise the gain of the amplifier as
a function of the measurement strength, and use interferometric methods to show
that the operation preserves the coherence of the signal.


title:
Two-dimensional symbiotic solitons and vortices in binary condensates
  with attractive cross-species interaction

abstract:
  We consider a two-dimensional (2D) two-component spinor system with cubic
attraction between the components and intra-species self-repulsion, which may
be realized in atomic Bose-Einstein condensates, as well as in a
quasi-equilibrium condensate of microcavity polaritons. Including a 2D
spatially periodic potential, which is necessary for the stabilization of the
system against the critical collapse, we use detailed numerical calculations
and an analytical variational approximation (VA) to predict the existence and
stability of several types of 2D symbiotic solitons in the spinor system.
Stability ranges are found for symmetric and asymmetric symbiotic fundamental
solitons and vortices, including hidden-vorticity (HV) modes, with opposite
vorticities in the two components. The VA produces exceptionally accurate
predictions for the fundamental solitons and vortices. The fundamental
solitons, both symmetric and asymmetric ones, are completely stable, in either
case when they exist as gap solitons or regular ones. The symmetric and
asymmetric vortices are stable if the inter-component attraction is stronger
than the intra-species repulsion, while the HV modes have their stability
region in the opposite case.


title:
Many-body Tunneling and Nonequilibrium Dynamics of Doublons in Strongly
  Correlated Quantum Dots

abstract:
  Quantum tunneling dominates coherent transport at low temperatures in many
systems of great interest. In this work we report a many--body tunneling (MBT),
by nonperturbatively solving the Anderson multi-impurity model, and identify it
a fundamental tunneling process on top of the well--acknowledged sequential
tunneling and cotunneling. We show that the MBT involves the dynamics of
doublons in strongly correlated systems. Proportional to the numbers of
dynamical doublons, the MBT can dominate the off--resonant transport in the
strongly correlated regime. A $T^{3/2}$--dependence of the MBT current on
temperature is uncovered and can be identified as a fingerprint of the MBT in
experiments. We also prove that the MBT can support the coherent long--range
tunneling of doublons, which is well consistent with recent experiments on
ultracold atoms. As a fundamental physical process, the MBT is expected to play
important roles in general quantum systems.


title: Upper bounds for partial spreads

abstract:
  A partial $t$-spread in $\mathbb{F}_q^n$ is a collection of $t$-dimensional
subspaces with trivial intersection such that each non-zero vector is covered
at most once. We present some improved upper bounds on the maximum sizes.


title: Completely Symmetric Resistance Forms on the Stretched Sierpinski Gasket

abstract:
  The stretched Sierpinski gasket, SSG for short, is the space obtained by
replacing every branching point of the Sierpinski gasket by an interval. It has
also been called "deformed Sierpinski gasket" or "Hanoi attractor". As a
result, it is the closure of a countable union of intervals and one might
expect that a diffusion on SSG is essentially a kind of gluing of the Brownian
motions on the intervals. In fact, there have been several works in this
direction. There still remains, however, "reminiscence" of the Sierpinski
gasket in the geometric structure of SSG and the same should therefore be
expected for diffusions. This paper shows that this is the case. In this work,
we identify all the completely symmetric resistance forms on SSG. A completely
symmetric resistance form is a resistance form whose restriction to every
contractive copy of SSG in itself is invariant under all geometrical symmetries
of the copy, which constitute the symmetry group of the triangle. We prove that
completely symmetric resistance forms on SSG can be sums of the Dirichlet
integrals on the intervals with some particular weights, or a linear
combination of a resistance form of the former kind and the standard resistance
form on the Sierpinski gasket.


title:
Subspace Estimation and Decomposition for Hybrid Analog-Digital
  Millimetre-Wave MIMO systems

abstract:
  In this work, we address the problem of channel estimation and precoding /
combining for the so-called hybrid millimeter wave (mmWave) MIMO architecture.
Our proposed channel estimation scheme exploits channel reciprocity in TDD MIMO
systems, by using echoing, thereby allowing us to implement Krylov subspace
methods in a fully distributed way. The latter results in estimating the right
(resp. left) singular subspace of the channel at the transmitter (resp.
receiver). Moreover, we also tackle the problem of subspace decomposition
whereby the estimated right (resp. left) singular subspaces are approximated by
a cascade of analog and digital precoder (resp. combiner), using an iterative
method. Finally we compare our scheme with an equivalent fully digital case and
conclude that a relatively similar performance can be achieved, however, with a
drastically reduced number of RF chains - 4 ~ 8 times less (i.e., massive
savings in cost and power consumption).


title: Knapsack problem for nilpotent groups

abstract:
  We prove that Knapsack problem (KP) is undecidable for any group of
nilpotency class two if the number of generators (without torsion) of the
derived subgroup is at least 322. This result together with the fact that if KP
is undecidable for a subgroup then it undecidable for the whole group allows us
extend our result to certain classes of polycyclic groups, linear groups and
nilpotent groups of higher nilpotency class.


title:
Reanalyzing variable directionality of gene expression in
  transgenerational epigenetic inheritance

abstract:
  A previous report claimed no evidence of transgenerational epigenetic
inheritance in a mouse model of in utero environmental exposure, based on the
observation that gene expression changes observed in the germ cells of G1 and
G2 male fetus were not in the same direction. A subsequent data reanalysis
however showed a statistically significant overlap between G1 and G2 genes
irrespective of direction, leading to the suggestion that, as phenotypic
variability in epigenetic transmission has been observed in several other
examples also, the above report provided evidence in favor of, not against,
transgenerational inheritance. This criticism has recently been questioned.
Here, it is shown that the questions raised are based not only on incorrect
statistical calculations but also on wrong premise that gene expression changes
do not constitute a phenotype.


title: Kantowski-Sachs Einstein-{\ae}ther perfect fluid models

abstract:
  We investigate Kantowski-Sachs models in Einstein-{\ae}ther theory with a
perfect fluid source using the singularity analysis to prove the integrability
of the field equations and dynamical system tools to study the evolution. We
find an inflationary source at early times, and an inflationary sink at late
times, for a wide region in the parameter space. The results by A. A. Coley, G.
Leon, P. Sandin and J. Latta (JCAP 12, 010, 2015), are then re-obtained as
particular cases. Additionally, we select other values for the non-GR
parameters which are consistent with current constraints, getting a very rich
phenomenology. In particular, we find solutions with infinite shear, zero
curvature, and infinite matter energy density in comparison with the Hubble
scalar. We also have stiff-like future attractors, anisotropic late-time
attractors, or both, in some special cases. Such results are developed
analytically, and then verified by numerics. Finally, the physical
interpretation of the new critical points is discussed.


title: Coordination and Antenna Domain Formation in Cloud-RAN systems

abstract:
  We study here the problem of Antenna Domain Formation (ADF) in cloud RAN
systems, whereby multiple remote radio-heads (RRHs) are each to be assigned to
a set of antenna domains (ADs), such that the total interference between the
ADs is minimized. We formulate the corresponding optimization problem, by
introducing the concept of \emph{interference coupling coefficients} among
pairs of radio-heads. We then propose a low-overhead algorithm that allows the
problem to be solved in a distributed fashion, among the aggregation nodes
(ANs), and establish basic convergence results. Moreover, we also propose a
simple relaxation to the problem, thus enabling us to characterize its maximum
performance. We follow a layered coordination structure: after the ADs are
formed, radio-heads are clustered to perform coordinated beamforming using the
well known Weighted-MMSE algorithm. Finally, our simulations show that using
the proposed ADF mechanism would significantly increase the sum-rate of the
system (with respect to random assignment of radio-heads).


title:
A statistical representation of the cosmological constant from finite
  size effects at the apparent horizon

abstract:
  In this paper we present a statistical description of the cosmological
constant in terms of massless bosons (gravitons). To this purpose, we use our
recent results implying a non vanishing temperature ${T_{\Lambda}}$ for the
cosmological constant. In particular, we found that a non vanishing
$T_{\Lambda}$ allows us to depict the cosmological constant $\Lambda$ as
composed of elementary oscillations of massless bosons of energy $\hbar\omega$
by means of the Bose-Einstein distribution. In this context, as happens for
photons in a medium, the effective phase velocity $v_g$ of these massless
excitations is not given by the speed of light $c$ but it is suppressed by a
factor depending on the number of quanta present in the universe at the
apparent horizon. We found interesting formulas relating the cosmological
constant, the number of quanta $N$ and the mean value $\overline{\lambda}$ of
the wavelength of the gravitons. In this context, we study the possibility to
look to the gravitons system so obtained as being very near to be a
Bose-Einstein condensate. Finally, an attempt is done to write down the
Friedmann flat equations in terms of $N$ and $\overline{\lambda}$.


title:
Sum-rate Maximization in Sub-28 GHz Millimeter-Wave MIMO Interfering
  Networks

abstract:
  MIMO systems in the lower part of the millimeter-wave spectrum band (i.e.,
below 28 GHz) do not exhibit enough directivity and selectively, as their
counterparts in higher bands of the spectrum (i.e., above 60 GHz), and thus
still suffer from the detrimental effect of interference, on the system
sum-rate. As such systems exhibit large numbers of antennas and short coherence
times for the channel, traditional methods of distributed coordination are
ill-suited, and the resulting communication overhead would offset the gains of
coordination. In this work, we propose algorithms for tackling the sum-rate
maximization problem, that are designed to address the above limitations. We
derive a lower bound on the sum-rate, a so-called DLT bound (i.e., a difference
of log and trace), shed light on its tightness, and highlight its decoupled
nature at both the transmitters and receivers. Moreover, we derive the solution
to each of the subproblems, that we dub non-homogeneous waterfilling (a
variation on the MIMO waterfilling solution), and underline an inherent
desirable feature: its ability to turn-off streams exhibiting low-SINR, and
contribute to greatly speeding up the convergence of the proposed algorithm. We
then show the convergence of the resulting algorithm, max-DLT, to a stationary
point of the DLT bound. Finally, we rely on extensive simulations of various
network configurations, to establish the fast-converging nature of our proposed
schemes, and thus their suitability for addressing the short coherence
interval, as well as the increased system dimensions, arising when managing
interference in lower bands of the millimeter wave spectrum. Moreover, our
results also suggest that interference management still brings about
significant performance gains, especially in dense deployments.


title: Hiring Doctors in E-Healthcare With Zero Budget

abstract:
  The doctors (or expert consultants) are the critical resources on which the
success of critical medical cases are heavily dependent. With the emerging
technologies (such as video conferencing, smartphone, etc.) this is no longer a
dream but a fact, that for critical medical cases in a hospital, expert
consultants from around the world could be hired, who may be present physically
or virtually. Earlier, this interesting situation by taking the expert
consultancies from outside the hospital had been studied, but under monetary
perspective. In this paper, for the first time, to the best of our knowledge,
we investigate the situation, where the below income group (BIG) people of the
society may be served efficiently through the expert consultancy by the
renowned doctors from outside of the hospital under zero budget. This will help
us saving many lives which will fulfil the present day need of biomedical
research. We propose three mechanisms: Random pick-assign mechanism (RanPAM),
Truthful optimal allocation mechanism (TOAM), and Truthful optimal allocation
mechanism for incomplete preferences (TOAM-IComP) to allocate the doctor to the
patient. With theoretical analysis, we demonstrate that the TOAM is
strategy-proof, and exhibits a unique core property. The mechanisms are also
validated with exhaustive experiments.


title:
Two orders of magnitude reduction in silicon membrane thermal
  conductivity by resonance hybridizations

abstract:
  The thermal conductivity of a freestanding single-crystal silicon membrane
may be reduced significantly by attaching nanoscale pillars on one or both
surfaces. Atomic resonances of the nanopillars locally and intrinsically couple
with the base membrane phonon modes causing these modes to hybridize and
flatten at each coupling location in the phonon band structure. The ensuing
group velocity reductions, which in principle may be tuned to take place across
silicon's full spectrum, lead to a lowering of the in-plane thermal
conductivity in the base membrane. Using equilibrium molecular dynamics
simulations, we report a staggering two orders of magnitude reduction in the
thermal conductivity at room temperature by this mechanism.


title: Wild ramification of nilpotent coverings and coverings of bounded degree

abstract:
  A finite \'etale map between irreducible, normal varieties is called tame, if
it is tamely ramified with respect to all partial compactifications whose
boundary is the support of a strict normal crossings divisor. We prove that if
the Galois group of a Galois covering contains a normal nilpotent subgroup of
index bounded by a constant N, then the covering is tame if and only if it is
tamely ramified with respect to a single distinguished partial compactification
only depending on N. The main tools used in the proof are Temkin's local purely
inseparable uniformization and a Lefschetz type theorem due to Drinfeld.


title: Exotic hadrons: review and perspectives

abstract:
  The physics of exotic hadrons is revisited and reviewed, with emphasis on
flavour configurations which have not yet been investigated. The constituent
quark model of multiquark states is discussed in some detail, as it can serve
as a guide for more elaborate approaches.


title:
Application of Origen2.1 in the decay photon spectrum calculation of
  spallation products

abstract:
  Origen2.1 is a widely used computer code for calculating the burnup, decay,
and processing of radioactive materials. However, the nuclide library of
Origen2.1 is used for existing reactors like pressurized water reactor, to
calculate the photon spectrum released by the decay of spallation products, we
have made specific libraries for the ADS tungsten spallation target, based on
the results given by a Monte Carlo code: FLUKA. All the data used to make the
Origen2.1 libraries is obtained from Nuclear structure & decay Data (NuDat2.6).
The accumulated activity of spallation products and the contribution of
nuclides to photon emission are given in this paper.


title: Restarting for the Tensor Infinite Arnoldi method

abstract:
  An efficient and robust restart strategy is important for any Krylov-based
method for eigenvalue problems. The tensor infinite Arnoldi method (TIAR) is a
Krylov-based method for solving nonlinear eigenvalue problems (NEPs). This
method can be interpreted as an Arnoldi method applied to a linear and infinite
dimensional eigenvalue problem where the Krylov basis consists of polynomials.
We propose new restart techniques for TIAR and analyze efficiency and
robustness. More precisely, we consider an extension of TIAR which corresponds
to generating the Krylov space using not only polynomials but also structured
functions that are sums of exponentials and polynomials, while maintaining a
memory efficient tensor representation. We propose two restarting strategies,
both derived from the specific structure of the infinite dimensional Arnoldi
factorization. One restarting strategy, which we call semi-explicit TIAR
restart, provides the possibility to carry out locking in a compact way. The
other strategy, which we call implicit TIAR restart, is based on the
Krylov-Schur restart method for linear eigenvalue problem and preserves its
robustness. Both restarting strategies involve approximations of the tensor
structured factorization in order to reduce complexity and required memory
resources. We bound the error in the infinite dimensional Arnoldi factorization
showing that the approximation does not substantially influence the robustness
of the restart approach. We illustrate the approaches by applying them to solve
large scale NEPs that arise from a delay differential equation and a wave
propagation problem. The advantages in comparison to other restart methods are
also illustrated.


title: On Designs for Recursive Least Squares Residuals to Detect Alternatives

abstract:
  Linear regression models are checked by a lack-of-fit (LOF) test to be sure
that the model is at least approximatively true. In many practical cases data
are sampled sequentially. Such a situation appears in industrial production
when goods are produced one after the other. So it is of some interest to check
the regression model sequentially. This can be done by recursive least squares
residuals. A sequential LOF test can be based on the recursive residual partial
sum process. In this paper we state the limit of the partial sum process of a
triangular array of recursive residuals given a constant regression model when
the number of observations goes to infinity. Furthermore, we state the
corresponding limit process for local alternatives. For specific alternatives
designs are determined dominating other designs in respect of power of the
sequential LOF test described above. In this context a result is given in which
$e^{-1}$ plays a crucial role.


title:
Higgs boson form factor effects in $t\bar t$ production by $W^-W^+$ and
  $ZZ$ fusion

abstract:
  We study the fusion processes $W^-W^+\to t\bar t$ and $ZZ\to t\bar t$
observable at a future $e^-e^+$ collider and we discuss their sensitivity to an
$Htt$ form factor which may be due to compositeness, in particular when the $H$
and the top quark have common constituents. We make an amplitude analysis and
illustrate which helicity amplitudes and cross sections for specific final
$t\bar t$ polarizations are especially sensitive to this form factor.


title: Numbers and Functions in Quantum Field Theory

abstract:
  We review recent results in the theory of numbers and single-valued functions
on the complex plane which arise in quantum field theory. We use the results to
calculate the renormalization functions $\beta$, $\gamma$, $\gamma_m$ of
dimensionally regularized $\phi^4$ theory in the minimal subtraction scheme up
to seven loops.


title: Activated hopping transport in anisotropic systems at low temperatures

abstract:
  Numerical calculations of anisotropic hopping transport based on the resistor
network model are presented. Conductivity is shown to follow the stretched
exponential dependence on temperature with exponents changing from 1/4 to 1 as
the wave functions become anisotropic and their localization length in the
direction of charge transport decreases. For sufficiently strong anisotropy,
this results in nearest-neighbor hopping at low temperatures due to the
formation of a single conduction path, which adjusts in the planes where the
wave functions overlap strongly. In the perpendicular direction, charge
transport follows variable-range hopping, a behavior that agrees with
experimental data on organic semiconductors.


title:
Limits on Lorentz invariance violation at the Planck energy scale from
  H.E.S.S. spectral analysis of the blazar Mrk 501

abstract:
  Some extensions to the Standard Model lead to the introduction of Lorentz
symmetry breaking terms, expected to induce deviations from Lorentz symmetry
around the Planck scale. A parameterization of effects due to Lorentz
invariance violation (LIV) can be introduced by adding an effective term to the
photon dispersion relation. This affects the kinematics of electron-positron
pair creation by TeV $\gamma$ rays on the extragalactic background light (EBL)
and translates into modifications of the standard EBL opacity for the TeV
photon spectra of extragalactic sources. Exclusion limits are presented,
obtained with the spectral analysis of H.E.S.S. observations taken on the
blazar Mrk 501 during the exceptional 2014 flare. The energy spectrum,
extending very significantly above 10 TeV, allows to place strong limits on LIV
in the photon sector at the level of the Planck energy scale for linear
perturbations in the photon dispersion relation, and provides the strongest
constraints presently for the case of quadratic perturbations.


title: On the Equivalence of Heat Kernels of Second-order parabolic operators

abstract:
  Let $P$ be a second-order, symmetric, and nonnegative elliptic operator with
real coefficients defined on noncompact Riemannian manifold $M$, and let $V$ be
a real valued function which belongs to the class of {\em small perturbation
potentials} with respect to the heat kernel of $P$ in $M$. We prove that under
some further assumptions (satisfying by a large classes of $P$ and $M$) the
positive minimal heat kernels of $P-V$ and of $P$ on $M$ are equivalent.
Moreover, the parabolic Martin boundary is stable under such perturbations, and
the cones of all nonnegative solutions of the corresponding parabolic equations
are affine homeomorphic


title: Radiation Damping by Thomson Scattering

abstract:
  Synchrotron radiation of relativistic electrons in storage rings naturally
leads to the process of damping of betatron oscillations. Damping time and
transverse beam emittance can be reduced by wigglers or undulators while the
beam parameters are still well defined by the common radiation integrals, based
on the properties of synchrotron radiation. However, the quantum excitation of
betatron oscillations in principle can be considerably reduced if an electron
radiation occurs due to the Thomson scattering in the periodic electromagnetic
field. After a brief introduction we compare radiation properties for different
cases and suggest the modification of the radiation integrals.


title: Geometric inequalities from phase space translations

abstract:
  We establish a quantum version of the classical isoperimetric inequality
relating the Fisher information and the entropy power of a quantum state. The
key tool is a Fisher information inequality for a state which results from a
certain convolution operation: the latter maps a classical probability
distribution on phase space and a quantum state to a quantum state. We show
that this inequality also gives rise to several related inequalities whose
counterparts are well-known in the classical setting: in particular, it implies
an entropy power inequality for the mentioned convolution operation as well as
the isoperimetric inequality, and establishes concavity of the entropy power
along trajectories of the quantum heat diffusion semigroup. As an application,
we derive a Log-Sobolev inequality for the quantum Ornstein-Uhlenbeck
semigroup, and argue that it implies fast convergence towards the fixed point
for a large class of initial states.


title: On the Inefficiency of Forward Markets in Leader-Follower Competition

abstract:
  Motivated by electricity markets, this paper studies the impact of forward
contracting in situations where firms have capacity constraints and
heterogeneous production lead times. We consider a model with two types of
firms - leaders and followers - that choose production at two different times.
Followers choose productions in the second stage but can sell forward contracts
in the first stage. Our main result is an explicit characterization of the
equilibrium outcomes. Classic results on forward contracting suggest that it
can mitigate market power in simple settings; however the results in this paper
show that the impact of forward markets in this setting is delicate - forward
contracting can enhance or mitigate market power. In particular, our results
show that leader-follower interactions created by heterogeneous production lead
times may cause forward markets to be inefficient, even when there are a large
number of followers. In fact, symmetric equilibria do not necessarily exist due
to differences in market power among the leaders and followers.


title: A Machine Learning Classifier for Fast Radio Burst Detection at the VLBA

abstract:
  Time domain radio astronomy observing campaigns frequently generate large
volumes of data. Our goal is to develop automated methods that can identify
events of interest buried within the larger data stream. The V-FASTR fast
transient system was designed to detect rare fast radio bursts (FRBs) within
data collected by the Very Long Baseline Array. The resulting event candidates
constitute a significant burden in terms of subsequent human reviewing time. We
have trained and deployed a machine learning classifier that marks each
candidate detection as a pulse from a known pulsar, an artifact due to radio
frequency interference, or a potential new discovery. The classifier maintains
high reliability by restricting its predictions to those with at least 90%
confidence. We have also implemented several efficiency and usability
improvements to the V-FASTR web-based candidate review system. Overall, we
found that time spent reviewing decreased and the fraction of interesting
candidates increased. The classifier now classifies (and therefore filters)
80-90% of the candidates, with an accuracy greater than 98%, leaving only the
10-20% most promising candidates to be reviewed by humans.


title: Mityagin's Extension Problem. Progress Report

abstract:
  Given a compact set $K\subset {\Bbb R}^d,$ let ${\mathcal E}(K)$ denote the
space of Whitney jets on $K$. The compact set $K$ is said to have the extension
property if there exists a continuous linear extension operator $W:{\mathcal
E}(K) \longrightarrow C^{\infty}({\Bbb R}^d)$. In 1961 B. S. Mityagin posed a
problem to give a characterization of the extension property in geometric
terms. We show that there is no such complete description in terms of densities
of Hausdorff contents or related characteristics. Also the extension property
cannot be characterized in terms of growth of Markov's factors for the set.


title: Law of localization in chemical reaction networks

abstract:
  In living cells, chemical reactions are connected by sharing their products
and substrates, and form complex networks, e.g. metabolic pathways. Here we
developed a theory to predict the sensitivity, i.e. the responses of
concentrations and fluxes to perturbations of enzymes, from network structure
alone. Responses turn out to exhibit two characteristic patterns,
$localization$ and $hierarchy$. We present a general theorem connecting
sensitivity with network topology that explains these characteristic patterns.
Our results imply that network topology is an origin of biological robustness.
Finally, we suggest a strategy to determine real networks from experimental
measurements.

categories: q-bio.MN math.DS physics.bio-ph q-bio.SC


title: CCD UBV Photometry and Kinematics of the Open Cluster NGC 225

abstract:
  We present the results of CCD $UBV$ photometric and spectroscopic
observations of the open cluster NGC 225. In order to determine the structural
parameters of NGC 225, we calculated the stellar density profile in the
cluster's field. We estimated the probabilities of the stars being physical
members of the cluster using the existing astrometric data. The most likely
members of the cluster were used in the determination of the astrophysical
parameters of the cluster. We calculated the mean radial velocity of the
cluster as $V_{r}=-8.3\pm 5.0$ km s$^{-1}$ from the optical spectra of eight
stars in the cluster's field. Using the U-B vs B-V two-colour diagram and UV
excesses of the F-G type main-sequence stars, the reddening and metallicity of
NGC 225 were inferred as $E(B-V)=0.151\pm 0.047$ mag and $[Fe/H]=-0.11\pm 0.01$
dex, respectively. We fitted the colour-magnitude diagrams of NGC 225 with the
PARSEC isochrones and derived the distance modulus, distance and age of the
cluster as $\mu_{V}=9.3\pm 0.07$ mag, d=585$\pm$20 pc and $t=900\pm 100$ Myr,
respectively. We also estimated the galactic orbital parameters and space
velocity components of the cluster and found that the cluster has a slightly
eccentric orbit of $e=0.07\pm 0.01$ and an orbital period of $P_{orb}= 255\pm
5$ Myr.


title: Some Properties of Dust Outside the Galactic Disk

abstract:
  The joint use of accurate near- and mid-infrared photometry from the 2MASS
and WISE catalogues has allowed the variations of the extinction law and the
dust grain size distribution in high Galactic latitudes (|b|>50) at distances
up to 3 kpc from the Galactic midplane to be analyzed. The modified method of
extrapolation of the extinction law applied to clump giants has turned out to
be efficient for separating the spatial variations of the sample composition,
metallicity, reddening, and properties of the medium. The detected spatial
variations of the coefficients E(H-W1)/E(H-Ks), E(H-W2)/E(H-Ks), and
E(H-W3)/E(H-Ks) are similar for all high latitudes and depend only on the
distance from the Galactic midplane. The ratio of short-wavelength extinction
to long-wavelength one everywhere outside the Galactic disk has been found to
be smaller than that in the disk and, accordingly, the mean dust grain size is
larger, while the grain size distribution in the range 0.5-11 microns is
shifted toward coarse dust. Specifically, the mean grain size initially
increases sharply with distance from the Galactic midplane, then decreases
gradually, approaching a value typical of the disk at $|Z|\approx2.4$ kpc, and,
further out, stabilizes or may increase again. The coefficients under
consideration change with coordinate $Z$ with a period of about 1312\pm40 pc,
coinciding every 656\pm20 pc to the south and the north and showing a
significant anticorrelation between their values in the southern and northern
hemispheres at intermediate Z. Thus, there exists a unified large-scale
periodic structure of the interstellar medium at high latitudes within at least
5 kpc. The same periodic variations have also been found for the extinction
coefficient Rv within 600 pc of the Galactic midplane through the reduction of
different photometric data for stars of different classes.


title: Capillarity problems with nonlocal surface tension energies

abstract:
  We explore the possibility of modifying the classical Gauss free energy
functional used in capillarity theory by considering surface tension energies
of nonlocal type. The corresponding variational principles lead to new
equilibrium conditions which are compared to the mean curvature equation and
Young's law found in classical capillarity theory. As a special case of this
family of problems we recover a nonlocal relative isoperimetric problem of
geometric interest.


title:
Scalarization in vector optimization by functions with uniform sublevel
  sets

abstract:
  In this paper, vector optimization is considered in the framework of decision
making and optimization in general spaces. Interdependencies between domination
structures in decision making and domination sets in vector optimization are
given. We prove some basic properties of efficient and of weakly efficient
points in vector optimization. Sufficient conditions for solutions to vector
optimization problems are shown using minimal solutions of functionals. We
focus on the scalarization by functions with uniform sublevel sets, which also
delivers necessary conditions for efficiency and weak efficiency. The functions
with uniform sublevel sets may be, e.g., continuous or even Lipschitz
continuous, convex, strictly quasiconcave or sublinear. They can coincide with
an order unit norm on a subset of the space.


title: Iteration problem for distributional chaos

abstract:
  We disprove the conjecture that distributional chaos of type 3 (briefly, DC3)
is iteration invariant and show that a slightly strengthened definition,
denoted by DC2$\frac{1}{2}$, is preserved under iteration, i.e. $f^n$ is
DC2$\frac{1}{2}$ if and only if $f$ is too. Unlike DC3, DC2$\frac{1}{2}$ is
also conjugacy invariant and implies Li-Yorke chaos. The definition of
DC2$\frac{1}{2}$ is the following: a pair $(x,y)$ is DC2$\frac{1}{2}$ iff
$\Phi_{(x,y)}(0)<\Phi^*_{(x,y)}(0)$, where $\Phi_{(x,y)}(\delta)$ (resp.
$\Phi^*_{(x,y)}(\delta)$) is lower (resp. upper) density of times $k$ when
$d(f^k(x),f^k(y))<\delta$ and both densities are defined at 0 as limits of
their values for $\delta\to 0^+$. Hence DC$2\frac{1}{2}$ shares similar
properties with DC1 and DC2 but unlike them, strict DC$2\frac{1}{2}$ systems
must have zero topological entropy.


title:
Heterogeneity of time delays determines synchronization of coupled
  oscillators

abstract:
  Network couplings of oscillatory large-scale systems, such as the brain, have
a space-time structure composed of connection strengths and signal transmission
delays. We provide a theoretical framework, which allows treating the spatial
distribution of time delays with regard to synchronization, by decomposing it
into patterns and therefore reducing the stability analysis into the tractable
problem of a finite set of delay-coupled differential equations. We analyse
delay-structured networks of phase oscillators and we find that, depending on
the heterogeneity of the delays, the oscillators group in phase-shifted,
anti-phase, steady, and non-stationary clusters, and analytically compute their
stability boundaries. These results find direct application in the study of
brain oscillations.


title:
Zeeman splitting of conduction band in HgTe quantum wells near the Dirac
  point

abstract:
  The Zeeman splitting of the conduction band in the HgTe quantum wells both
with normal and inverted spectrum has been studied experimentally in a wide
electron density range. The simultaneous analysis of the SdH oscillations in
low magnetic fields at different tilt angles and of the shape of the
oscillations in moderate magnetic fields gives a possibility to find the ratio
of the Zeeman splitting to the orbital one and anisotropy of g-factor. It is
shown that the ratios of the Zeeman splitting to the orbital one are close to
each other for both types of structures, with a normal and inverted spectrum
and they are close enough to the values calculated within kP method. In
contrast, the values of g-factor anisotropy in the structures with normal and
inverted spectra is strongly different and for both cases differs significantly
from the calculated ones. We believe that such disagreement with calculations
is a result of the interface inversion asymmetry in the HgTe quantum well,
which is not taken into account in the kP calculations.


title:
Zeros of optimal polynomial approximants: Jacobi matrices and
  Jentzsch-type theorems

abstract:
  We study the structure of the zeros of optimal polynomial approximants to
reciprocals of functions in Hilbert spaces of analytic functions in the unit
disk. In many instances, we find the minimum possible modulus of occurring
zeros via a nonlinear extremal problem associated with norms of Jacobi
matrices. We examine global properties of these zeros and prove Jentzsch-type
theorems describing where they accumulate. As a consequence, we obtain detailed
information regarding zeros of reproducing kernels in weighted spaces of
analytic functions.


title: Explicit Short Intervals for Primes in Arithmetic Progressions on GRH

abstract:
  We prove explicit versions of Cram\'er's theorem for primes in arithmetic
progressions, on the assumption of the generalized Riemann hypothesis.


title: Sloppy nuclear energy density functionals: effective model reduction

abstract:
  Concepts from information geometry are used to analyse parameter sensitivity
for a nuclear energy density functional, representative of a class of
semi-empirical functionals that start from a microscopically motivated ansatz
for the density dependence of the energy of a system of protons and neutrons.
It is shown that such functionals are sloppy, characterized by an exponential
range of sensitivity to parameter variations. Responsive to only a few stiff
parameter combinations, they exhibit an exponential decrease of sensitivity to
variations of the remaining soft parameters. By interpreting the space of model
predictions as a manifold embedded in the data space, with the parameters of
the functional as coordinates on the manifold, it is also shown that the
exponential distribution of model manifold widths corresponds to the
distribution of parameter sensitivity. Using the Manifold Boundary
Approximation Method, we illustrate how to systematically construct effective
nuclear density functionals of successively lower dimension in parameter space
until sloppiness is eventually eliminated and the resulting functional contains
only stiff combinations of parameters.


title:
Chimera states in pulse coupled neural networks: the influence of
  dilution and noise

abstract:
  We analyse the possible dynamical states emerging for two symmetrically pulse
coupled populations of leaky integrate-and-fire neurons. In particular, we
observe broken symmetry states in this set-up: namely, breathing chimeras,
where one population is fully synchronized and the other is in a state of
partial synchronization (PS) as well as generalized chimera states, where both
populations are in PS, but with different levels of synchronization. Symmetric
macroscopic states are also present, ranging from quasi-periodic motions, to
collective chaos, from splay states to population anti-phase partial
synchronization. We then investigate the influence disorder, random link
removal or noise, on the dynamics of collective solutions in this model. As a
result, we observe that broken symmetry chimera-like states, with both
populations partially synchronized, persist up to 80 \% of broken links and up
to noise amplitudes 8 \% of threshold-reset distance. Furthermore, the
introduction of disorder on symmetric chaotic state has a constructive effect,
namely to induce the emergence of chimera-like states at intermediate dilution
or noise level.


title:
Andreev bound states in superconductor/ferromagnet point contact Andreev
  reflection spectra

abstract:
  As charge carriers traverse a single superconductor ferromagnet interface
they experience an additional spin-dependent phase angle which results in spin
mixing and the formation of a bound state called the Andreev Bound State. This
state is an essential component in the generation of long range spin triplet
proximity induced superconductivity and yet the factors controlling the degree
of spin mixing and the formation of the bound state remain elusive. Here we
demonstrate that point contact Andreev reflection can be used to detect the
bound state and extract the resulting spin mixing angle. By examining spectra
taken from La1.15Sr1.85Mn2O7 single crystal - Pb junctions, together with a
compilation of literature data on highly spin polarised systems, we show that
the existence of the Andreev Bound State both resolves a number of long
standing controversies in the Andreev literature as well as defining a route to
quantify the strength of spin mixing at superconductor-ferromagnet interfaces.
Intriguingly we find that for these high transparency junctions, the spin
mixing angle appears to take a relatively narrow range of values across all the
samples studied. The ferromagnets we have chosen to study share a common
property in terms of their spin arrangement, and our observations may point to
the importance of this property in determining the spin mixing angle under
these circumstances.


title:
Weighted difference of g-factors of light Li-like and H-like ions for an
  improved determination of the fine-structure constant

abstract:
  A weighted difference of the $g$-factors of the Li- and H-like ion of the
same element is studied and optimized in order to maximize the cancellation of
nuclear effects. To this end, a detailed theoretical investigation is performed
for the finite nuclear size correction to the one-electron $g$-factor, the one-
and two-photon exchange effects, and the QED effects. The coefficients of the
$Z\alpha$ expansion of these corrections are determined, which allows us to set
up the optimal definition of the weighted difference. It is demonstrated that,
for moderately light elements, such weighted difference is nearly free from
uncertainties associated with nuclear effects and can be utilized to extract
the fine-structure constant from bound-electron $g$-factor experiments with an
accuracy competitive with or better than its current literature value.


title: Regularity of the vanishing ideal over a parallel composition of paths

abstract:
  Let G be a graph obtained by taking r>=2 paths and identifying all first
vertices and identifying all the last vertices. We compute the
Castelnuovo--Mumford regularity of the quotient S/I(X), where S is the
polynomial ring on the edges of G and I(X) is the vanishing ideal of the
projective toric subset parameterized by G. The case we consider is the first
case where the regularity was unknown, following earlier computations (by
several authors) of the regularity when G is a tree, cycle, complete graph or
complete bipartite graph, but specially in light of the reduction of the
computation of the regularity in the bipartite case to the computation of the
regularity of the blocks of G. We also prove new inequalities relating the
Castelnuovo--Mumford regularity of S/I(X) with the combinatorial structure of
G, for a general graph.


title: Probing TRAPPIST-1-like systems with K2

abstract:
  The search for small planets orbiting late M dwarfs holds the promise of
detecting Earth-size planets for which their atmospheres could be characterised
within the next decade. The recent discovery of TRAPPIST-1 entertains hope that
these systems are common around hosts located at the bottom of the main
sequence. In this Letter, we investigate the ability of the repurposed Kepler
mission (K2) to probe planetary systems similar to TRAPPIST-1. We perform a
consistent data analysis of 189 spectroscopically confirmed M5.5 to M9 late M
dwarfs from campaigns 1-6 to search for planet candidates and inject transit
signals with properties matching TRAPPIST-1b and c. We find no transiting
planet candidates across our K2 sample. Our injection tests show that K2 is
able to recover both TRAPPIST-1 planets for 10% of the sample only, mainly
because of the inefficient throughput at red wavelengths resulting in
Poisson-limited performance for these targets. Increasing injected planetary
radii to match GJ1214b's size yields a recovery rate of 70%. The strength of K2
is its ability to probe a large number of cool hosts across the different
campaigns, out of which the recovery rate of 10% may turn into bona-fide
detections of TRAPPIST-1 like systems within the next two years.


title:
Tides and angular momentum redistribution inside low-mass stars hosting
  planets: a first dynamical model

abstract:
  We introduce a general mathematical framework to model the internal transport
of angular momentum in a star hosting a close-in planetary/stellar companion.
By assuming that the tidal and rotational distortions are small and that the
deposit/extraction of angular momentum induced by stellar winds and tidal
torques are redistributed solely by an effective eddy-viscosity that depends on
the radial coordinate, we can formulate the model in a completely analytic way.
It allows us to compute simultaneously the evolution of the orbit of the
companion and of the spin and the radial differential rotation of the star. An
illustrative application to the case of an F-type main-sequence star hosting a
hot Jupiter is presented. The general relevance of our model to test more
sophisticated numerical dynamical models and to study the internal rotation
profile of exoplanet hosts, submitted to the combined effects of tides and
stellar winds, by means of asteroseismology are discussed.


title:
Higher spin super-Cotton tensors and generalisations of the
  linear-chiral duality in three dimensions

abstract:
  In three spacetime dimensions, (super)conformal geometry is controlled by the
(super) Cotton tensor. We present a new duality transformation for N-extended
supersymmetric theories formulated in terms of the linearised super-Cotton
tensor or its higher spin extensions for the cases N=2, 1, 0. In the N=2 case,
this transformation is a generalisation of the linear-chiral duality, which is
known to provide a dual description in terms of chiral superfields for general
models of self-interacting N=2 vector multiplets in three dimensions and N=1
tensor multiplets in four dimensions. For superspin-1 (gravitino multiplet),
superspin-3/2 (supergravity multiplet) and higher superspins s>3/2, the duality
transformation relates a higher-derivative theory to one containing at most two
derivatives at the component level. In the N=1 case, we introduce gauge
prepotentials for higher spin superconformal gravity and construct the
corresponding super-Cotton tensors, as well as the higher spin extensions of
the linearised N=1 conformal supergravity action. Our N=1 duality
transformation is a higher spin extension of the known superfield duality
relating the massless N=1 vector and scalar multiplets. In the
non-supersymmetric (N=0) case, the gauge prepotentials for higher spin
conformal geometry (both bosonic and fermionic) and the corresponding Cotton
tensors can be obtained from their N=1 counterparts by carrying out N=1 --> N=0
reduction. In the bosonic sector, this reduction is shown to lead to the Cotton
tensors for higher spins constructed by Pope and Townsend, and by Damour and
Deser in the spin-3 case. Our N=0 duality transformation is a higher spin
extension of the vector-scalar duality.


title:
On the $\mathcal{R}$-boundedness of solution operator families for
  two-phase Stokes resolvent equations

abstract:
  The aim of this paper is to show the existence of $\mathcal{R}$-bounded
solution operator families for two-phase Stokes resolvent equations in
$\dot\Omega=\Omega_+\cup\Omega_-$, where $\Omega_\pm$ are uniform $W_r^{2-1/r}$
domains of $N$-dimensional Euclidean space $\mathbf{R}^N$ ($N\geq 2$,
$N<r<\infty$). More precisely, given a uniform $W_r^{2-1/r}$ domain $\Omega$
with two boundaries $\Gamma_\pm$ satisfying $\Gamma_+\cap\Gamma_-=\emptyset$,
we suppose that some hypersurface $\Gamma$ divides $\Omega$ into two
sub-domains, that is, there exist domains $\Omega_\pm\subset\Omega$ such that
$\Omega_+\cap\Omega_-=\emptyset$ and
$\Omega\setminus\Gamma=\Omega_+\cup\Omega_-$, where
$\Gamma\cap\Gamma_+=\emptyset$, $\Gamma\cap\Gamma_-=\emptyset$, and the
boundaries of $\Omega_\pm$ consist of two parts $\Gamma$ and $\Gamma_\pm$,
respectively. The domains $\Omega_\pm$ are filled with viscous, incompressible,
and immiscible fluids with density $\rho_\pm$ and viscosity $\mu_\pm$,
respectively. Here $\rho_\pm$ are positive constants, while
$\mu_\pm=\mu_\pm(x)$ are functions of $x\in\mathbf{R}^N$. On the boundaries
$\Gamma$, $\Gamma_+$, and $\Gamma_-$, we consider an interface condition, a
free boundary condition, and the Dirichlet boundary condition, respectively. We
also show, by using the $\mathcal{R}$-bounded solution operator families, some
maximal $L_p\text{-}L_q$ regularity as well as generation of analytic semigroup
for a time-dependent problem associated with the two-phase Stokes resolvent
equations. This kind of problems arises in the mathematical study of the motion
of two viscous, incompressible, and immiscible fluids with free surfaces.


title:
Time dependence of the electron and positron components of the cosmic
  radiation measured by the PAMELA experiment between July 2006 and December
  2015

abstract:
  Cosmic-ray electrons and positrons are a unique probe of the propagation of
cosmic rays as well as of the nature and distribution of particle sources in
our Galaxy. Recent measurements of these particles are challenging our basic
understanding of the mechanisms of production, acceleration and propagation of
cosmic rays. Particularly striking are the differences between the low energy
results collected by the space-borne PAMELA and AMS-02 experiments and older
measurements pointing to sign-charge dependence of the solar modulation of
cosmic-ray spectra. The PAMELA experiment has been measuring the time variation
of the positron and electron intensity at Earth from July 2006 to December 2015
covering the period for the minimum of solar cycle 23 (2006-2009) till the
middle of the maximum of solar cycle 24, through the polarity reversal of the
heliospheric magnetic field which took place between 2013 and 2014. The
positron to electron ratio measured in this time period clearly shows a
sign-charge dependence of the solar modulation introduced by particle drifts.
These results provide the first clear and continuous observation of how drift
effects on solar modulation have unfolded with time from solar minimum to solar
maximum and their dependence on the particle rigidity and the cyclic polarity
of the solar magnetic field.


title: A stability approach for solving multidimensional quadratic BSDEs

abstract:
  We establish an existence and uniqueness result for a class of
multidimensional quadratic backward stochastic differential equations (BSDE).
This class is characterized by constraints on some uniform a priori estimate on
solutions of a sequence of approximated BSDEs. We also present effective
examples of applications. Our approach relies on the strategy developed by
Briand and Elie in [Stochastic Process. Appl. 123 2921--2939] concerning scalar
quadratic BSDEs.


title:
Discrimination between close hypotheses about Weibull and log-Weibull
  type distributions by the higher order statistics

abstract:
  The proposed paper discusses the problem of discrimination between close
hypotheses about distributions belonging to the Gumbel maximum domain of
attraction. The distinctive feature of the proposed work is using only k higher
order statistics of the sample in the construction of criteria, because there
are many situations when we do not know the whole sample, as it occurs in the
problems linked with safety, life span, catastrofes, sea level and other. This
work is the first in the series of the author's works that deal with the
statistics of extrema.


title: Weak Nanoscale Chaos And Anomalous Relaxation in DNA

abstract:
  Anomalous non-exponential relaxation in hydrated biomolecules is commonly
attributed to the complexity of the free-energy landscapes, similarly to
polymers and glasses. It was found recently that the hydrogen-bond breathing of
terminal DNA base pairs exhibits a slow power-law relaxation attributable to
weak Hamiltonian chaos, with parameters similar to experimental data. Here, the
relationship is studied between this motion and spectroscopic signals measured
in DNA with a small molecular photoprobe inserted into the base-pair stack. To
this end, the earlier computational approach in combination with an analytical
theory is applied to the experimental DNA fragment. It is found that the
intensity of breathing dynamics is strongly increased in the internal base
pairs that flank the photoprobe, with anomalous relaxation quantitatively close
to that in terminal base pairs. A physical mechanism is proposed to explain the
coupling between the relaxation of base-pair breathing and the experimental
response signal. It is concluded that the algebraic relaxation observed
experimentally is very likely a manifestation of weakly chaotic dynamics of
hydrogen-bond breathing in the base pairs stacked to the photoprobe, and that
the weak nanoscale chaos can represent an ubiquitous hidden source of
non-exponential relaxation in ultrafast spectroscopy.


title: Unruh thermalization, gluon condensation and freeze-out

abstract:
  The deconfinement transition and the hadronization mechanism at high energy
are related to the quark-antiquark string breaking and the corresponding
temperature depends on the string tension $\sigma$. In the Unruh scheme of
hadron production it turns out $T = \sqrt{\sigma/2\pi}$, with $\sigma \simeq
\E$, the vacuum energy density. In heavy ion collisions at lower energy, i.e.
large baryonchemical potential, $\mu_B$, the dynamics is dominated by Fermi
statistics and baryon repulsion. However one can still consider $\E$ as the
relevant physical scale and its evaluation as a function of the baryon density,
in a nuclear matter approach, gives dynamical information on the $\mu_B$
dependence of the hadronization temperature and on the value of the critical
end point in the $T-\mu_B$ plane.


title:
A generalization and short proof of a theorem of Hano on affine vector
  fields

abstract:
  We prove that a bounded affine vector field on a complete Finsler manifold is
a Killing vector field. This generalizes the analogous result of Hano for
Riemannian manifolds. Even though our result is more general, the proof is
significantly simpler.


title:
Isothermal Langevin dynamics in systems with power-law
  spatially-dependent friction

abstract:
  We study the dynamics of Brownian particles in a heterogeneous
one-dimensional medium with a spatially-dependent diffusion coefficient of the
form $D(x)\sim |x|^c$, at constant temperature. The particle's probability
distribution function (PDF) is calculated both analytically, by solving Fick's
diffusion equation, and from numerical simulations of the underdamped Langevin
equation. At large times, the PDFs calculated by both approaches yield
identical results, corresponding to subdiffusion for $c<0$, and superdiffusion
for $0<c<1$. For $c>1$, the diffusion equation predicts that the particles
accelerate. Here, we show that this phenomenon, previously considered in
several works as an illustration for the possible dramatic effects of
spatially-dependent thermal noise, is unphysical. We argue that in an
isothermal medium, the motion cannot exceed the ballistic limit ($\left\langle
x^2\right\rangle \sim t^2$). The ballistic limit is reached when the friction
coefficient drops sufficiently fast at large distances from the origin, and is
correctly captured by Langevin's equation.


title: Probing Quantum Interference Effects in the Work Distribution

abstract:
  What is the role of coherence in determining the distribution of work done on
a quantum system? We approach this question from an operational perspective and
consider a setup in which the internal energy of a closed system is recorded by
a quantum detector before and after the system is acted upon by an external
drive. We find that the resulting work distribution depends on the initial
state of the detector as well as on the choice of the final measurement. We
consider two complementary measurement schemes, both of which show clear
signatures of quantum interference. We specifically discuss how to implement
these schemes in the circuit QED architecture, using an artificial atom as the
system and a quantized mode of the electromagnetic field as the detector.
Different measurement schemes can be realized by preparing the field either in
a superposition of Fock states or in a coherent state and exploiting
state-of-the art techniques for the characterization of microwave radiation at
the quantum level. More generally, the single bosonic mode we utilize is
arguably the minimal quantum detector capable of capturing the complementary
aspects of the work distribution discussed here.


title: Non-Kondo many-body physics in a Majorana-based Kondo type system

abstract:
  We carry out a theoretical analysis of a prototypical Majorana system, which
demonstrates the existence of a Majorana-mediated many-body state and an
associated intermediate low-energy fixed point. Starting from two Majorana
bound states, hosted by a Coulomb-blockaded topological superconductor and each
coupled to a separate lead, we derive an effective low-energy Hamiltonian,
which displays a Kondo-like character. However, in contrast to the Kondo model
which tends to a strong- or weak-coupling limit under renormalization, we show
that this effective Hamiltonian scales to an intermediate fixed point, whose
existence is contingent upon teleportation via the Majorana modes. We conclude
by determining experimental signatures of this fixed point, as well as the
exotic many-body state associated with it.


title:
Strong decays of the $X(2500)$ newly observed by the BESIII
  Collaboration

abstract:
  Basing on the observation of a new $J^{PC}=0^{-+}$ state, $X(2500)$, in the
partial wave analysis of the decay $J/\psi\rightarrow\gamma X\rightarrow
\gamma\phi\phi$ performed by the BESIII Collaboration, we have evaluated the
strong decays of the $X(2500)$ as the $4^1S_0$ and $5^1S_0$ $s\bar{s}$ states
in the $^3P_0$ meson decay model. The predicted total decay width for the
$4^1S_0$ $s\bar{s}$ is about 894.5 MeV, and the one for the $5^1S_0$ $s\bar{s}$
is about 271.1 MeV, which is in agreement with the experimental data
$\Gamma_{X(2500)}=230^{+64+56}_{-35-33}$ MeV. By considering the mass and the
total strong decay width of the $X(2500)$, we propose that the $X(2500)$ state
can be interpreted as a candidate of the $5^1S_0$ $s\bar{s}$ state.