title:
Invariant manifolds of parabolic fixed points (I). Existence and
  dependence on parameters

abstract:
  In this paper we study the existence and regularity of stable manifolds
associated to fixed points of parabolic type in the differentiable and analytic
cases, using the parametrization method. The parametrization method relies on a
suitable approximate solution of a functional equation. In the case of
parabolic points, if the manifolds have dimension two or higher, in general
this approximation cannot be obtained in the ring of polynomials but as a sum
of homogeneous functions and it is given in~\cite{BFM2015b}. Assuming a
sufficiently good approximation is found, here we provide an "a posteriori"
result which gives a true invariant manifold close to the approximated one. In
the differentiable case, in some cases, there is a loss of regularity.
  We also consider the case of parabolic periodic orbits of periodic vector
fields and the dependence of the manifolds on parameters. Examples are
provided. We apply our method to prove that in several situations, namely,
related to the parabolic infinity in the elliptic spatial three body problem,
these invariant manifolds exist and do have polynomial approximations.


title:
On Burenkov's extension operator preserving Sobolev-Morrey spaces on
  Lipschitz domains

abstract:
  We prove that Burenkov's Extension Operator preserves Sobolev spaces built on
general Morrey spaces, including classical Morrey spaces. The analysis concerns
bounded and unbounded open sets with Lipschitz boundaries in the n-dimensional
Euclidean space.


title:
Invariant manifolds of parabolic fixed points (II). Approximations by
  sums of homogeneous functions

abstract:
  We study the computation of local approximations of invariant manifolds of
parabolic fixed points and parabolic periodic orbits of periodic vector fields.
If the dimension of these manifolds is two or greater, in general, it is not
possible to obtain polynomial approximations. Here we develop an algorithm to
obtain them as sums of homogeneous functions by solving suitable cohomological
equations. We deal with both the differentiable and analytic cases. We also
study the dependence on parameters. In the companion paper, Invariant manifolds
of parabolic fixed points (I), these approximations are used to obtain the
existence of true invariant manifolds close by. Examples are provided.


title: Effective Vinogradov's mean value theorem via efficient boxing

abstract:
  We combine Wooley's efficient congruencing method with earlier work of
Vinogradov and Hua to get effective bounds on Vinogradov's mean value theorem.


title:
Estimation of the lifetime of small helium bubbles near tungsten
  surfaces -- a methodological study

abstract:
  Under low energy and high flux/fluence irradiation of helium (He) atoms, the
formation and bursting of He bubbles on tungsten (W) surfaces play important
roles in the morphological evolution of component surfaces and impurity
production in fusion reactors. Microscopically, the bursting of He bubbles is a
stochastic process, and He bubbles have statistically average lifetimes. In the
present paper, a molecular dynamics-based method was developed to extract, for
the first time, the lifetime of He bubbles near tungsten surfaces. It was found
that He bubble bursting can be treated as an activated event. Its occurrence
frequency or, equivalently, the average lifetime of bubbles follows the
Arrhenius equation. For a given bubble size, the activation energy exhibits a
good linear dependence with the depth, and the pre-exponential factor obeys the
Meyer-Nedle rule. These results are useful for establishing a model in
multi-scale simulations of impurity production in the fusion plasma and of the
morphological evolution of component surfaces.


title:
Consistency of multi-time Dirac equations with general interaction
  potentials

abstract:
  In 1932, Dirac proposed a formulation in terms of multi-time wave functions
as candidate for relativistic many-particle quantum mechanics. A well-known
consistency condition that is necessary for existence of solutions strongly
restricts the possible interaction types between the particles. It was
conjectured by Petrat and Tumulka that interactions described by multiplication
operators are generally excluded by this condition, and they gave a proof of
this claim for potentials without spin-coupling. Under smoothness assumptions
of possible solutions we show that there are potentials which are admissible,
give an explicit example, however, show that none of them fulfills the
physically desirable Poincar\'e invariance. We conclude that in this sense
Dirac's multi-time formalism does not allow to model interaction by
multiplication operators, and briefly point out several promising approaches to
interacting models one can instead pursue.


title: A Characteristic Dynamic Mode Decomposition

abstract:
  Temporal or spatial structures are readily extracted from complex data by
modal decompositions like Proper Orthogonal Decomposition (POD) or Dynamic Mode
Decomposition (DMD). Subspaces of such decompositions serve as reduced order
models and define either spatial structures in time or temporal structures in
space. On the contrary, convecting phenomena pose a major problem to those
decompositions. A structure traveling with a certain group velocity will be
perceived as a plethora of modes in time or space respectively. This manifests
itself for example in poorly decaying singular values when using a POD. The
poor decay is counter-intuitive, since a single structure is expected to be
represented by a few modes. The intuition proves to be correct and we show that
in a properly chosen reference frame along the characteristics defined by the
group velocity, a POD or DMD reduces moving structures to a few modes, as
expected. Beyond serving as a reduced model, the resulting entity can be used
to define a constant or minimally changing structure in turbulent flows. This
can be interpreted as an empirical counterpart to exact coherent structures. We
present the method and its application to a head vortex of a compressible
starting jet.


title: Single gap superconductivity in beta-Bi2Pd

abstract:
  beta-Bi2Pd compound has been proposed as another example of a multi-gap
superconductor [Y. Imai et al., J. Phys. Soc. Jap. 81, 113708 (2012)]. Here, we
report on measurements of several important physical quantities capable to show
a presence of multiple energy gaps on our superconducting single crystals of
beta-Bi2Pd with the critical temperature Tc close to 5 K. The calorimetric
study via a sensitive ac technique shows a sharp anomaly at the superconducting
transition, however only a single energy gap is detected. Also other
characteristics inferred from calorimetric measurements as the field dependence
of the Sommerfeld coefficient and the temperature and angular dependence of the
upper critical magnetic field point unequivocally to standard single s-wave gap
superconductivity. The Hall-probe magnetometry provides the same result from
the analysis of the temperature dependence of the lower critical field. A
single-gapped BCS density of states is detected by the scanning tunneling
spectroscopy measurements. Then, the bulk as well as the surface sensitive
probes evidence a standard conventional superconductivity in this system where
the topologically protected surface states have been recently detected by ARPES
[M. Sakano et al., Nature Comm. 6, 8595 (2015)] .


title: Bohmian Mechanics, Collapse Models and the emergence of Classicality

abstract:
  We discuss the emergence of classical trajectories in Bohmian Mechanics (BM),
when a macroscopic object interacts with an external environment. We show that
in such a case the conditional wave function of the system follows a dynamics
which, under reasonable assumptions, corresponds to that of the
Ghirardi-Rimini-Weber (GRW) collapse model. As a consequence, Bohmian
trajectories evolve classically. Our analysis also shows how the GRW
(istantaneous) collapse process can be derived by an underlying continuous
interaction of a quantum system with an external agent, thus throwing a light
on how collapses can emerge from a deeper level theory.


title: Invariant measures for piecewise continuous maps

abstract:
  We say that $f:[0,1]\to [0,1]$ is a {\it piecewise continuous interval map}
if there exists a partition $0=x_0<x_1<\cdots<x_{d}<x_{d+1}=1$ of $[0,1]$ such
that $f\vert_{(x_{i-1},x_i)}$ is continuous and the lateral limits
$w_0^+=\lim_{x\to 0^+} f(x)$, $w_{d+1}^-=\lim_{x\to 1^-} f(x)$,
\mbox{$w_i^{-}=\lim_{x\to x_i^-} f(x)$} and $w_i^{+}=\lim_{x\to x_i^+} f(x)$
exist for each $i$. We prove that every piecewise continuous interval map
without connections admits an invariant Borel probability measure. We also
prove that every injective piecewise continuous interval map with no
connections and no periodic orbits is topologically semi-conjugate to an
interval exchange transformation.


title: A novel mass generation scheme for an Abelian vector field

abstract:
  A novel mass generation procedure for an Abelian vector field is proposed.
This procedure is based on the construction of a class of gauge theories whose
free limit describes a free massless vector field and a set of massless real
scalar fields by means of the antifield-BRST deformation technique. The
relationship between our results and those arising from the Higgs mechanism
based on the spontaneous symmetry breaking of an Abelian gauge symmetry is
emphasized. Some examples with one, two, and three scalars are given.


title:
Nonlinear hydrodynamical evolution of eccentric Keplerian discs in two
  dimensions: validation of secular theory

abstract:
  We perform global two-dimensional hydrodynamical simulations of Keplerian
discs with free eccentricity over thousands of orbital periods. Our aim is to
determine the validity of secular theory in describing the evolution of
eccentric discs, and to explore their nonlinear evolution for moderate
eccentricities. Linear secular theory is found to correctly predict the
structure and precession rates of discs with small eccentricities. However,
discs with larger eccentricities (and eccentricity gradients) are observed to
precess faster (retrograde relative to the orbital motion), at a rate that
depends on their eccentricities (and eccentricity gradients). We derive
analytically a nonlinear secular theory for eccentric gas discs, which explains
this result as a modification of the pressure forces whenever eccentric orbits
in a disc nearly intersect. This effect could be particularly important for
highly eccentric discs produced in tidal disruption events, or for narrow
gaseous rings; it might also play a role in causing some of the variability in
superhump binary systems. In two dimensions, the eccentricity of a moderately
eccentric disc is long-lived and persists throughout the duration of our
simulations. Eccentric modes are however weakly damped by their interaction
with non-axisymmetric spiral density waves (driven by the Papaloizou-Pringle
instability, which occurs in our idealised setup with solid walls), as well as
numerical diffusion.

categories: astro-ph.EP astro-ph.HE astro-ph.SR physics.flu-dyn


title: Irreducible Green Functions Method applied to nanoscopic systems

abstract:
  The equation of motion method (EOM) for Green functions is one of the tools
used in the analysis of quantum dot system coupled with metallic and
superconducting leads. We investigate modified EOM, based on differentiation of
double-time temperature dependent Green functions both after primary time t and
secondary time t'. Our EOM approach allows us to obtain the Abrikosov-Suhl
resonance both in the particle-hole symmetric case but also in the asymmetric
cases. We will apply the irreducible Green functions technique to analyses the
EOM for dot system. This method give a workable decoupling scheme breaking the
infinite set of Green function equations. We apply this technique for
calculating the density of the states and the differential conductance of
single-level quantum dot with Coulomb repulsion attached to one metallic and
one superconducting leads (N-QD-SC). Our results are compared with the
experimental data and previous calculations.


title:
Comparing the properties of the X-shaped bulges of NGC 4710 and the
  Milky Way with MUSE

abstract:
  We used the new ESO VLT instrument MUSE to obtain spectral and imaging
coverage of NGC 4710. The wide area and excellent sampling of the MUSE integral
field spectrograph allows us to investigate the dynamical properties of the
X-shaped bulge of NGC 4710 and compare it with the properties of the Milky
Way's own X-shaped bulge. We measured the radial velocities, velocity
dispersion, and stellar populations using a penalized pixel full spectral
fitting technique adopting simple stellar populations models, on a 1' x 1' area
centred on the bulge of NGC 4710. We have constructed the velocity maps of the
bulge of NGC 4710 and we investigated the presence of vertical metallicity
gradients. These properties were compared to those of the Milky Way bulge and
as well as to a simulated galaxy with boxy/peanut bulge. We find the
line-of-sight velocity maps and 1D rotation curves of the bulge of NGC 4710 to
be remarkably similar to those of the Milky Way bulge. Some specific
differences that were identified are in good agreement with the expectations
from variations in the bar orientation angle. The bulge of NGC 4710 has a
boxy-peanut morphology with a pronounced X-shape, showing no indication of any
additional spheroidally distributed bulge population, in which we measure a
vertical metallicity gradient of 0.35 dex/kpc. The general properties of NGC
4710 are very similar to those observed in the MW bulge. However, it has been
suggested that the MW bulge has an additional component that is comprised of
the oldest, most metal-poor stars and which is not part of the boxy-peanut
bulge structure. Such a population is not observed in NGC 4710, but could be
hidden in the integrated light we observed.


title:
Ligand-Surface Interactions and Surface Oxidation of Colloidal PbSe
  Quantum Dots Revealed by Thin-film Positron Annihilation Methods

abstract:
  Positron Two Dimensional Angular Correlation of Annihilation Radiation
(2D-ACAR) measurements reveal modifications of the electronic structure and
composition at the surfaces of PbSe quantum dots (QDs), deposited as thin
films, produced by various ligands containing either oxygen or nitrogen atoms.
In particular, the 2D-ACAR measurements on thin films of colloidal PbSe QDs
capped with oleic acid ligands yield an increased intensity in the electron
momentum density (EMD) at high momenta compared to PbSe quantum dots capped
with oleylamine. Moreover, the EMD of PbSe QDs is strongly affected by the
small ethylediamine ligands, since these molecules lead to small distances
between QDs and favor neck formation between near neighbor QDs, inducing
electronic coupling between neighboring QDs. The high sensitivity to the
presence of oxygen atoms at the surface can be also exploited to monitor the
surface oxidation of PbSe QDs upon exposure to air. Our study clearly
demonstrates that positron annihilation spectroscopy applied to thin films can
probe surface transformations of colloidal semiconductor QDs embedded in
functional layers.


title:
Challenges in Design of Kitaev Materials: Magnetic Interactions from
  Competing Energy Scales

abstract:
  In this study, we reanalyze the magnetic interactions in the Kitaev spin
liquid candidate materials Na$_2$IrO$_3$, $\alpha$-RuCl$_3$, and
$\alpha$-Li$_2$IrO$_3$ using nonperturbative exact diagonalization methods.
These methods are more appropriate given the relatively itinerant nature of the
systems suggested in previous works. We treat all interactions up to third
neighbours on equal footing. The computed terms reveal significant long range
coupling, bond-anisotropy, and/or off-diagonal couplings which we argue
naturally explain the observed ordered phases in these systems. Given these
observations, the potential for realizing the spin-liquid state in real
materials is analyzed, and synthetic challenges are defined and explained.


title:
Observation of Majorana fermions with spin selective Andreev reflection
  in the vortex of topological superconductor

abstract:
  Majorana fermion (MF) whose antiparticle is itself has been predicted in
condensed matter systems. Signatures of the MFs have been reported as zero
energy modes in various systems. More definitive evidences are highly desired
to verify the existence of the MF. Very recently, theory has predicted MFs to
induce spin selective Andreev reflection (SSAR), a novel magnetic property
which can be used to detect the MFs. Here we report the first observation of
the SSAR from MFs inside vortices in Bi2Te3/NbSe2 hetero-structure, in which
topological superconductivity was previously established. By using
spin-polarized scanning tunneling microscopy/spectroscopy (STM/STS), we show
that the zero-bias peak of the tunneling differential conductance at the vortex
center is substantially higher when the tip polarization and the external
magnetic field are parallel than anti-parallel to each other. Such strong spin
dependence of the tunneling is absent away from the vortex center, or in a
conventional superconductor. The observed spin dependent tunneling effect is a
direct evidence for the SSAR from MFs, fully consistent with theoretical
analyses. Our work provides definitive evidences of MFs and will stimulate the
MFs research on their novel physical properties, hence a step towards their
statistics and application in quantum computing.


title:
From dots to stripes to sheets - Shape control of lead sulfide
  nanostructures

abstract:
  Controlling anisotropy in nanostructures is a challenging but rewarding task
since confinement in one or more dimensions influences the physical and
chemical properties of the items decisively. In particular, semiconducting
nanostructures can be tailored to gain optimized properties to work as
transistors or absorber material in solar cells. We demonstrate that the shape
of colloidal lead sulfide nanostructures can be tuned from spheres to stripes
to sheets by means of the precursor concentrations, the concentration of a
chloroalkane co-ligand and the synthesis temperature. All final structures
still possess at least one dimension in confinement. Electrical transport
measurements complement the findings.


title: Maximum Efficiency of Low-Dissipation Heat Engines at Arbitrary Power

abstract:
  We investigate maximum efficiency at a given power for low-dissipation heat
engines. Close to maximum power, the maximum gain in efficiency scales as a
square root of relative loss in power and this scaling is universal for a broad
class of systems. For the low-dissipation engines, we calculate the maximum
gain in efficiency for an arbitrary fixed power. We show that the engines
working close to maximum power can operate at considerably larger efficiency
compared to the efficiency at maximum power. Furthermore, we introduce
universal bounds on maximum efficiency at a given power for low-dissipation
heat engines. These bounds represent direct generalization of the bounds on
efficiency at maximum power obtained by Esposito et al. Phys. Rev. Lett. 105,
150603 (2010). We derive the bounds analytically in the regime close to maximum
power and for small power values. For the intermediate regime we present strong
numerical evidence for the validity of the bounds.


title: The Magnetic Classification of Solar Active Regions 1992 - 2015

abstract:
  The purpose of this letter is to address a blind-spot in our knowledge of
solar active region statistics. To the best of our knowledge there are no
published results showing the variation of the Mount Wilson magnetic
classifications as a function of solar cycle based on modern observations. We
show statistics for all active regions reported in the daily Solar Region
Summary from 1992 January 1 to 2015 December 31. We find that the $\alpha$ and
$\beta$ class active regions (including all sub-groups e.g. $\beta\gamma$,
$\beta\delta$) make up fractions of approximately 20% and 80% of the sample
respectively. This fraction is relatively constant during high levels of
activity, however, an increase in the $\alpha$ fraction to about 35% and and a
decrease in the $\beta$ fraction to about 65% can be seen near each solar
minimum and is statistically significant at the 2-$\sigma$ level. Over 30% of
all active regions observed during the years of solar maxima were appended with
the classifications $\gamma$ and/or $\delta$, while these classifications
account for only a fraction of a percent during the years near the solar
minima. This variation in the active region types indicates that the formation
of complex active regions may be due to the pileup of frequent emergence of
magnetic flux during solar maximum, rather than the emergence of complex,
monolithic flux structures.


title:
Inability of the entropy vector method to certify nonclassicality in
  linelike causal structures

abstract:
  Bell's theorem shows that our intuitive understanding of causation must be
overturned in light of quantum correlations. Nevertheless, quantum mechanics
does not permit signalling and hence a notion of cause remains. Understanding
this notion is not only important at a fundamental level, but also for
technological applications such as key distribution and randomness expansion.
It has recently been shown that a useful way to decide which classical causal
structures could give rise to a given set of correlations is to use entropy
vectors. These are vectors whose components are the entropies of all subsets of
the observed variables in the causal structure. The entropy vector method
employs causal relationships among the variables to restrict the set of
possible entropy vectors. Here, we consider whether the same approach can lead
to useful certificates of non-classicality within a given causal structure.
Surprisingly, we find that for a family of causal structures that include the
usual bipartite Bell structure they do not. For all members of this family, no
function of the entropies of the observed variables gives such a certificate,
in spite of the existence of nonclassical correlations. It is therefore
necessary to look beyond entropy vectors to understand cause from a quantum
perspective.


title: A generally-relativistic gauge classification of the Dirac fields

abstract:
  We consider generally-relativistic gauge transformations for the spinorial
fields finding two mutually exclusive but together exhaustive classes in which
fermions are placed adding supplementary information to the results obtained by
Lounesto, and identifying quantities analogous to the momentum vector and the
Pauli-Lubanski axial vector we discuss how our results are similar to those
obtained by Wigner; by taking into account the system of Dirac field equations
we will investigate the consequences for the dynamics: and in particular we
shall address the problem of getting the non-relativistic approximation in a
consistent way. We are going to comment on extensions.


title:
Search for s channel single top quark production in pp collisions at
  sqrt(s) = 7 and 8 TeV

abstract:
  A search is presented for single top quark production in the s channel in
proton-proton collisions with the CMS detector at the CERN LHC in decay modes
of the top quark containing a muon or an electron in the final state. The
signal is extracted through a maximum-likelihood fit to the distribution of a
multivariate discriminant defined using boosted decision trees to separate the
expected signal contribution from background processes. The analysis uses data
collected at centre-of-mass energies of 7 and 8 TeV and corresponding to
integrated luminosities of 5.1 and 19.7 inverse femtobarns, respectively. The
measured cross sections of 7.1 +/- 8.1 pb (at 7 TeV) and 13.4 +/- 7.3 pb (at 8
TeV) result in a best fit value of 2.0 +/- 0.9 for the combined ratio of the
measured and expected values. The signal significance is 2.5 standard
deviations, and the upper limit on the rate relative to the standard model
expectation is 4.7 at 95% confidence level.


title:
Local Lipschitz Stability for Inverse Robin Problems in Some Elliptic
  and Parabolic Systems

abstract:
  In this work, we shall study the nonlinear inverse problems of recovering the
Robin coefficients in elliptic and parabolic systems of second order, and
establish their local Lipschitz stabilities. Some local Lipschitz stability was
derived for an elliptic inverse Robin problem. We shall first restructure the
arguments in \cite{chou04} for the local Lipschitz stability so that the
stability follows from three basic conditions for the elliptic inverse Robin
problem. The new arguments are then generalized to help establish a novel local
Lipschitz stability for parabolic inverse Robin problems.


title: Structure of K\"ahler potential for D-term inflationary attractor models

abstract:
  Minimal chaotic models of D-term inflation predicts too large primordial
tensor perturbations. Although it can be made consistent with observations
utilizing higher order terms in the K\"ahler potential, expansion is not
controlled in the absence of symmetries. We comprehensively study the
conditions of K\"ahler potential for D-term plateau-type potentials and discuss
its symmetry. They include the alpha-attractor model with a massive vector
supermultiplet and its generalization leading to pole inflation of arbitrary
order. We extend the models so that it can describe Coulomb phase, gauge
anomaly is cancelled, and fields other than inflaton are stabilized during
inflation. We also point out a generic issue for large-field D-term inflation
that the masses of the non-inflaton fields tend to exceed the Planck scale.


title: Multidimensional factorization through helical mapping

abstract:
  This paper proposes a new perspective on the problem of multidimensional
spectral factorization, through helical mapping: $d$-dimensional ($d$D) data
arrays are vectorized, processed by $1$D cepstral analysis and then remapped
onto the original space. Partial differential equations (PDEs) are the basic
framework to describe the evolution of physical phenomena. We observe that the
minimum phase helical solution asymptotically converges to the $d$D semi-causal
solution, and allows to decouple the two solutions arising from PDEs describing
physical systems. We prove this equivalence in the theoretical framework of
cepstral analysis, and we also illustrate the validity of helical factorization
through a $2$D wave propagation example and a $3$D application to
helioseismology.


title:
Modifications of the Lifshitz-Kosevich formula in two-dimensional Dirac
  systems

abstract:
  Starting from the Luttinger-Ward functional we derive an expression for the
oscillatory part of the grand potential of a two dimensional Dirac system in a
magnetic field. We perform the computation for the clean and the disordered
system, and we study the effect of electron-electron interactions on the
oscillations. Unlike in the two dimensional electron gas (2DEG), a finite
temperature and impurity scattering also affects the oscillation frequency.
Furthermore, we find that in graphene, compared to the 2DEG, additional
interaction induced damping effects occur: to two-loop order electron-electron
interactions do lead to an additional damping factor in the amplitude of the
Lifshitz-Kosevich-formula.


title:
Predicting Mercury's Precession using Simple Relativistic Newtonian
  Dynamics

abstract:
  We present a new simple relativistic model for planetary motion describing
accurately the anomalous precession of the perihelion of Mercury and its
origin. The model is based on transforming Newton's classical equation for
planetary motion from absolute to real spacetime influenced by the
gravitational potential and introducing the concept of influenced direction.


title:
Resonant enhancement of Raman scattering in metamaterials with hybrid
  electromagnetic and plasmonic resonances

abstract:
  A tri-layer metamaterial perfect absorber of light, consisting of (Al/ZnS/Al)
films with the top aluminium layer patterned as an array of circular disk
nanoantennas, is investigated for resonantly enhancing Raman scattering from
C-60 fullerene molecules deposited on the metamaterial. The metamaterial is
designed to have resonant bands due to plasmonic and electromagnetic resonances
at the Raman pump frequency (725 nm) as well as Stokes emission bands. The
Raman scattering from C60 on the metamaterial with resonantly matched bands is
measured to be enhanced by an order of magnitude more than from C60 on
metamaterials with off-resonant absorption bands peaked at 1090 nm. The Raman
pump is significantly enhanced due to the resonance with a propagating surface
plasmon band, while the highly impedance matched electromagnetic resonance is
expected to couple out the Raman emission efficiently. The nature and
hybridization of the plasmonic and electromagnetic resonances to form compound
resonances are investigated by numerical simulations.


title: On Resolvability of a Graph Associated to a Finite Vector Space

abstract:
  The metric dimension of non-component graph, associated to a finite vector
space, is determined.
  It is proved that the exchange property holds for resolving sets of the
graph, except a special case.
  Some results are also related to an intersection graph.


title: A Jamming-resilient Algorithm for Self-triggered Network Coordination

abstract:
  The issue of cyber-security has become ever more prevalent in the analysis
and design of cyber-physical systems. In this paper, we investigate
self-triggered consensus networks in the presence of communication failures
caused by Denialof- Service (DoS) attacks. A general framework is considered in
which the network links can fail independent of each other. By introducing a
notion of Persistency-of-Communication (PoC), we provide an explicit
characterization of DoS frequency and duration under which consensus can be
preserved by suitably designing time-varying control and communication
policies. An explicit characterization of the effects of DoS on the consensus
time is also provided. The considered notion of PoC is compared with classic
average connectivity conditions that are found in pure continuous-time
consensus networks. Finally, examples are given to substantiate the analysis.


title: Resilient Control under Denial-of-Service:Robust Design

abstract:
  In this paper, we study networked control systems in the presence of
Denial-of-Service (DoS) attacks, namely attacks that prevent transmissions over
the communication network. The control objective is to maximize frequency and
duration of the DoS attacks under which closed-loop stability is not destroyed.
Analog and digital predictor-based controllers with state resetting are
proposed, which achieve the considered control objective for a general class of
DoS signals. An example is given to illustrate the proposed solution approach.


title:
Large Slowdown of Water Dynamics at Stacked Phospholipid Membranes for
  Increasing Hydration Level: All-Atoms Molecular Dynamics

abstract:
  Water hydrating phospholipid membranes determine their stability and
function, as well as their interaction with other molecules. In this article we
study, using all-atom molecular dynamics simulations, the rotational and
translational dynamical properties of water molecules confined in stacked
phospholipid membranes at different levels of hydration, from poorly hydrated
to a completely hydrated membrane. We find that both the translational and the
reorientation dynamics of water are dramatically slowed down as the hydration
is reduced. Analyzing in details the structure and dynamics of the hydrogen
bond at the interface, we show that both those among water molecules and those
between water and lipids slow down by decreasing the hydration, however the
latter are always slower than the former. By increasing hydration, water
saturates all the possible hydrogen bonds with the lipids and, by further
increase of hydration, the hydrogen bonds among waters becomes the majority.
However, the dynamics of the water-lipids hydrogen bonds becomes up to one
order of magnitude slower than that of the water-water hydrogen bonds, inducing
a large slowing down of the dynamics of the entire system even at large
hydration level.


title:
A coordinate ascent method for solving semidefinite relaxations of
  non-convex quadratic integer programs

abstract:
  We present a coordinate ascent method for a class of semidefinite programming
problems that arise in non-convex quadratic integer optimization. These
semidefinite programs are characterized by a small total number of active
constraints and by low-rank constraint matrices. We exploit this special
structure by solving the dual problem, using a barrier method in combination
with a coordinate-wise exact line search. The main ingredient of our algorithm
is the computationally cheap update at each iteration and an easy computation
of the exact step size. Compared to interior point methods, our approach is
much faster in obtaining strong dual bounds. Moreover, no explicit separation
and reoptimization is necessary even if the set of primal constraints is large,
since in our dual approach this is covered by implicitly considering all primal
constraints when selecting the next coordinate.


title:
Production of ultracold ground state LiRb molecules by photoassociation
  through a resonantly coupled state

abstract:
  We report on a resonantly coupled 2(1) - 4 (1) photoassociation resonance in
LiRb. This pair of states displays interesting decay physics that hint at
interference-like effects caused by two different decay paths. We observe decay
to predominantly $X \ ^1\Sigma^+ \ v=43$, with significant numbers of molecules
produced in $X \ ^1\Sigma^+ \ v=2$ - 12. This photoassociation resonance also
produces $\sim$300 $X \ ^1\Sigma^+ \ v=0 \ J=0$ molecules/second. Finally, we
identify a stimulated Raman adiabatic passage transfer pathway from $v=43$ to
$v=0$ that has the potential to produce up to $2 \times 10^5$ LiRb
molecules/second in the $X \ ^1\Sigma^+ \ v=0 \ J=0$ state.


title: The effects of turbulence generated in Big Bang nucleosynthesis

abstract:
  The continuity equation requires that energy released in nuclear fusion flows
away from the point of interaction and is not immediately thermalised into the
CMB. It is seen that consequently the bulk of thermo-nuclear energy released in
BBN is converted by radiation pressure to kinetic energy of gas motions and
generates instability in homogeneous initial conditions. High levels of
turbulence follow, triggering the Jeans mechanism and leading to the formation
of galaxies and large-scale structure in the order of 10 Myrs. Friedmann
cosmology is perturbed, creating a fractal Voronoi matter distribution and
providing energy for reionisation. In keeping with observations, general
relativity predicts that there is no bound on the size of the structures
produced. The true (overall) rate of expansion is substantially below the
observed (local) value of Hubble's constant, and is consistent with published
estimates from the CMB for void models. The CMB is predicted to show near
flatness over the observed region. It is seen from observation of fluid flows,
from established physics, and from numerical solution of the Navier-Stokes
equations that bisymmetric spiral vortices form where gas flows meet. These
vortices necessarily have flat rotation curves at large radii and create
conditions for spiral galaxy formation. It is shown by N-body simulation that
enduring Sa, Sb and Sc spiral galaxies result from appropriate initial
conditions. The simulations and analysis of spiral potential show that orbital
velocities are greater than would be the case in an axisymmetric potential.


title: Geodesics of McVittie Spacetime with a Phantom Cosmological Background

abstract:
  We investigate the geodesics of a Schwarzschild spacetime embedded in an
isotropic expanding cosmological background (McVittie metric). We focus on
bound particle geodesics in a background including matter and phantom dark
energy with constant dark energy equation of state parameter $w<-1$ involving a
future Big Rip singularity at a time $t_{\ast}$. Such geodesics have been
previously studied in the Newtonian approximation and found to lead to
dissociation of bound systems at a time $t_{rip}<t_{\ast}$ which for fixed
background $w$, depends on a single dimensionless parameter $\bar{\omega}_0$
related to the angular momentum and depending on the mass and the size of the
bound system. We extend this analysis to large massive bound systems where the
Newtonian approximation is not appropriate and we compare the derived
dissociation time with the corresponding time in the context of the Newtonian
approximation. By identifying the time when the effective potential minimum
disappears due to the repulsive force of dark energy we find that the
dissociation time of bound systems occurs earlier than the prediction of the
Newtonian approximation. However, the effect is negligible for all existing
cosmological bound systems and it would become important only in hypothetical
bound extremely massive ($10^{20} M_\odot$) and large ($100Mpc$) bound systems.
We verify this result by explicit solution of the geodesic equations. This
result is due to an interplay between the repulsive phantom dark energy effects
and the existence of the well known innermost stable orbits of Schwarzschild
spacetimes.


title:
Numerical modeling of exciton-polariton Bose--Einstein condensate in a
  microcavity

abstract:
  A novel, optimized numerical method of modeling of an exciton-polariton
superfluid in a semiconductor microcavity was proposed. Exciton-polaritons are
spin-carrying quasiparticles formed from photons strongly coupled to excitons.
They possess unique properties, interesting from the point of view of
fundamental research as well as numerous potential applications. However, their
numerical modeling is challenging due to the structure of nonlinear
differential equations describing their evolution. In this paper, we propose to
solve the equations with a modified Runge--Kutta method of 4th order, further
optimized for efficient computations. The algorithms were implemented in form
of C++ programs fitted for parallel environments and utilizing vector
instructions. The programs form the EPCGP suite which have been used for
theoretical investigation of exciton-polaritons.


title:
Tight-Binding Approximations to Time-Dependent Density Functional Theory
  - a fast approach for the calculation of electronically excited states

abstract:
  We propose a new method of calculating electronically excited states that
combines a density functional theory (DFT) based ground state calculation with
a linear response treatment that employs approximations used in the
time-dependent density functional based tight binding (TD-DFTB) approach. The
new method termed TD-DFT+TB does not rely on the DFTB parametrization and is
therefore applicable to systems involving all combinations of elements. We show
that the new method yields UV/Vis absorption spectra that are in excellent
agreement with computationally much more expensive time-dependent density
functional theory (TD-DFT) calculations. Errors in vertical excitation energies
are reduced by a factor of two compared to TD-DFTB.


title:
Spin-flip processes and radiative decay of dark intravalley excitons in
  transition metal dichalcogenide monolayers

abstract:
  We perform a theoretical study of radiative decay of dark intravalley
excitons in transition metal dichalcogenide monolayers. This decay necessarily
involves an electronic spin flip. The intrinsic decay mechanism due to
interband spin-flip dipole moment perpendicular to the monolayer plane, gives a
rate about 100--1000 times smaller than that of bright excitons. However, we
find that this mechanism also introduces an energy splitting due to a local
field effect, and the whole oscillator strength is contained in the
higher-energy component, while the lowest-energy state remains dark and needs
an extrinsic spin-flip mechanism for the decay. Rashba effect due to a
perpendicular electric field or a dielectric substrate, gives a negligible
radiative decay rate (about $10^7$ times slower than that of bright excitons).
Spin flip due to Zeeman effect in a sufficiently strong in-plane magnetic field
can give a decay rate comparable to that due to the intrinsic interband
spin-flip dipole.


title: Cosmological consequences of an adiabatic matter creation process

abstract:
  In this paper we investigate the cosmological consequences of a continuous
matter creation associated with the production of particles by the
gravitational field acting on the quantum vacuum. To illustrate this, three
phenomenological models are considered. An equivalent scalar field description
is presented for each models. The effects on the cosmic microwave background
power spectrum are analyzed for the first time in the context of adiabatic
matter creation cosmology. Further, we introduce a model independent treatment,
$Om$, which depends only on the Hubble expansion rate and the cosmological
redshift to distinguish any cosmological model from $\Lambda$CDM by providing a
null test for the cosmological constant, meaning that, for any two redshifts
$z_1$, $z_2$, $Om (z)$ is same, i.e. $Om (z_1)- Om (z_2)= 0$. Also, this
diagnostic can differentiate between several cosmological models by indicating
their quintessential/ phantom behavior without knowing the accurate value of
the matter density, and the present value of the Hubble parameter. For our
models, we find that particle production rate is inversely proportional to
$Om$. Finally, the validity of the generalized second law of thermodynamics
bounded by the apparent horizon has been examined.


title: From the stable to the exotic: clustering in light nuclei

abstract:
  A great deal of research work has been undertaken in alpha-clustering study
since the pioneering discovery of 12C+12C molecular resonances half a century
ago. Our knowledge on physics of nuclear molecules has increased considerably
and nuclear clustering remains one of the most fruitful domains of nuclear
physics, facing some of the greatest challenges and opportunities in the years
ahead. The occurrence of "exotic" shapes in light N=Z alpha-like nuclei is
investigated. Various approaches of the superdeformed and hyperdeformed bands
associated with quasimolecular resonant structures are presented. Evolution of
clustering from stability to the drip-lines is examined: clustering aspects
are, in particular, discussed for light exotic nuclei with large neutron excess
such as neutron-rich Oxygen isotopes with their complete spectroscopy.


title:
An Offspring of Multivariate Extreme-Value Theory: The
  Max-Characteristic Function

abstract:
  This paper introduces max-characteristic functions (max-CFs), which are an
offspring of multivariate extreme-value theory. A max-CF characterizes the
distribution of a random vector in R^d , whose components are nonnegative and
have finite expectation. Pointwise convergence of max-CFs is shown to be
equivalent with convergence with respect to the Wasserstein metric. The space
of max-CFs is not closed in the sense of pointwise convergence. An inversion
formula for max-CFs is established.


title:
A multiscale nonequilibrium model for melting of metal powder bed
  subjected to constant heat flux

abstract:
  A multiscale numerical model based on nonequilibrium thermal effect for
melting of metal powder bed subjected to constant heat flux is developed. The
volume shrinkage due to density change is taken into account. The
nonequilibrium model is discretized by an implicit finite difference method and
solved numerically using an iterative tri-diagonal matrix algorithm. The
evolutions of powder bed surface temperature and various interfacial locations
as well as the melting temperature range during the melting process are
investigated. The results show that liquid region, upper and lower parts of
mushy zone are formed on the top of unsintered zone as the melting progresses.
The duration of the preheating stage shortens and the melting rate accelerates
as the initial porosity or initial temperature increases while particle size
has much less effect on the melting process. The parametric study shows the
melting temperature range of the powder bed widens with increasing initial
porosity, decreasing initial temperature or increasing particle size.


title: Mapping PAH sizes in NGC 7023 with SOFIA

abstract:
  NGC 7023 is a well-studied reflection nebula, which shows strong emission
from polycyclic aromatic hydrocarbon (PAH) molecules in the form of aromatic
infrared bands (AIBs). The spectral variations of the AIBs in this region are
connected to the chemical evolution of the PAH molecules which, in turn,
depends on the local physical conditions. We use the capabilities of SOFIA to
observe a 3.2' x 3.4' region of NGC 7023 at wavelengths that we observe with
high spatial resolution (2.7") at 3.3 and 11.2 um. We compare the SOFIA images
with existing images of the PAH emission at 8.0 um (Spitzer), emission from
evaporating very small grains (eVSG) extracted from Spitzer-IRS spectral cubes,
the ERE (HST and CFHT), and H_2 (2.12 um). We create maps of the 11.2/3.3 um
ratio to probe the morphology of the PAH size distribution and the 8.0/11.2 um
ratio to probe the PAH ionization. We make use of an emission model and of
vibrational spectra from the NASA Ames PAHdb to translate the 11.2/3.3 um ratio
to PAH sizes. The 11.2/3.3 um map shows the smallest PAH concentrate on the PDR
surface (H_2 and extended red emission) in the NW and South PDR. We estimated
that PAHs in the NW PDR bear, on average, a number of carbon atoms (N_c) of ~70
in the PDR cavity and ~50 at the PDR surface. In the entire nebula, the results
reveal a factor of 2 variation in the size of the PAH. We relate these size
variations to several models for the evolution of the PAH families when they
traverse from the molecular cloud to the PDR. The PAH size map enables us to
follow the photochemical evolution of PAHs in NGC 7023. Small PAHs result from
the photo-evaporation of VSGs as they reach the PDR surface. Inside the PDR
cavity, the PAH abundance drops as the smallest PAH are broken down. The
average PAH size increases in the cavity where only the largest species survive
or are converted into C_60 by photochemical processing.


title: Batched Lazy Decision Trees

abstract:
  We introduce a batched lazy algorithm for supervised classification using
decision trees. It avoids unnecessary visits to irrelevant nodes when it is
used to make predictions with either eagerly or lazily trained decision trees.
A set of experiments demonstrate that the proposed algorithm can outperform
both the conventional and lazy decision tree algorithms in terms of computation
time as well as memory consumption, without compromising accuracy.


title:
Avalanche boron fusion by laser picosecond block ignition with magnetic
  trapping for clean and economic reactor

abstract:
  After the very long consideration of the ideal energy source by fusion of the
protons of light hydrogen with the boron isotope 11 (boron fusion HB11) the
very first two independent measurements of very high reaction gains by lasers
basically opens a fundamental breakthrough. The non-thermal plasma block
ignition with extremely high power laser pulses above petawatt of picosecond
duration in combination with up to ten kilotesla magnetic fields for trapping
has to be combined to use the measured high gains as proof of an avalanche
reaction for an environmentally clean, low cost and lasting energy source as
potential option against global warming. The unique HB11 avalanche reaction is
are now based on elastic collisions of helium nuclei (alpha particles) limited
only to a reactor for controlled fusion energy during a very short time within
a very small volume.


title: On the limitations of analysing worst-case dynamic energy of processing

abstract:
  This paper examines dynamic energy consumption caused by data during software
execution on deeply embedded microprocessors, which can be significant on some
devices. In worst-case energy consumption analysis, energy models are used to
find the most costly execution path. Taking each instruction's worst case
energy produces a safe but overly pessimistic upper bound. Algorithms for safe
and tight bounds would be desirable. We show that finding exact worst-case
energy is NP-hard, and that tight bounds cannot be approximated with guaranteed
safety. We conclude that any energy model targeting tightness must either
sacrifice safety or accept overapproximation proportional to data-dependent
energy.


title: Reducing the number of inputs in nonlocal games

abstract:
  In this work we show how a vector-valued version of Schechtman's empirical
method can be used to reduce the number of inputs in a nonlocal game $G$ while
preserving the quotient $\beta^*(G)/\beta(G)$ of the quantum over the classical
bias. We apply our method to the Khot-Vishnoi game, with exponentially many
questions per player, to produce another game with polynomially many ($N\approx
n^8$) questions so that the quantum over the classical bias is $\Omega
(n/\log^2 n)$.


title:
Period-Luminosity relations derived from the OGLE-III First-overtone
  mode Cepheids in the Magellanic Clouds

abstract:
  We present multi-band Period-Luminosity (PL) relations for first-overtone
mode Cepheids in the Small Magellanic Cloud (SMC). We derive optical band PL
relations and the Wesenheit function using $VI$ mean magnitudes from the
Optical Gravitational Lensing Experiment (OGLE-III) survey. We cross-match
OGLE-III first-overtone mode Cepheids to the 2MASS and SAGE-SMC catalogs to
derive PL relations at near-infrared ($JHK_s$) and mid-infrared
($3.6~\&~4.5\mu\mathrm{m}$) wavelengths. We test for possible non-linearities
in these PL relations using robust statistical tests and find a significant
break only in the optical-band PL relations at 2.5 days for first-overtone mode
Cepheids. We do not find statistical evidence for a non-linearity in these PL
relations at 1 day. The multi-band PL relations for fundamental-mode Cepheids
in the SMC also exhibit a break at 2.5 days. We suggest that the period break
around 2.5 days is related to sharp changes in the light curve parameters for
SMC Cepheids. We also derive new optical and mid-infrared band PL relations for
first-overtone mode Cepheids in the Large Magellanic Cloud (LMC). We compare
multi-band PL relations for first-overtone mode Cepheids in the Magellanic
Clouds and find a significant difference in the slope of the $V$-band PL
relations but not for $I$-band PL relations. The slope of PL relations are
found to be consistent in most of the infrared bands. A relative distance
modulus of $\Delta\mu=0.49\pm0.02$~mag between the two clouds is estimated
using multi-band PL relations for the first-overtone mode Cepheids in the SMC
and LMC.


title: Phase structure of a holographic double monolayer Dirac semimetal

abstract:
  We study a holographic D3/probe-D5-brane model of a double monolayer Dirac
semimetal in a magnetic field and in the presence of a nonzero temperature.
Intra- and inter-layer exciton condensates can form by varying the balanced
charge density on the layers, the spatial separation and the temperature.
Constant temperature phase diagrams for a wide range of layer separations and
charge densities are found. The presence of a finite temperature makes the
phase diagrams extremely rich and in particular leads to the appearance of a
symmetric phase which was missing at zero temperature.


title:
60 GHz Outdoor Urban Measurement Study of the Feasibility of Multi-Gbps
  mm-Wave Cellular Networks

abstract:
  Future 5G cellular networks are expected to exploit the abundant spectrum
resources of the millimeter-wave (mm-wave) bands to satisfy demand for
multi-Gbps mobile links anticipated by exponential data traffic growth.
However, given the directional nature of mm-wave links, the feasibility of
mm-wave mobile networks is critically dependent on efficient antenna
beamsteering and a rich inventory of strong LOS (line-of-sight) and NLOS (non
line-of-sight) paths from effective reflectors in the urban environment. In
this paper we report results from detailed angular measurements of 60 GHz links
at an example outdoor pico-cellular site in a mixed-use urban environment
typical of European cities. Our work is the first to systematically analyze the
beamsteering requirements of future mm-wave cellular networks based on real
measurements. Our results reveal that the urban environment provides
substantial opportunities for multi-Gbps mm-wave connectivity, but that the
availability of strong LOS/NLOS links is highly location and
orientation-specific. Our results also show that high speed mm-wave links are
very sensitive to beam misalignment. This has important implications for
practical mm-wave cellular network design: (i) high-precision beamsteering is
required to maintain stable data rates even for quasi-stationary users; and
(ii) providing seamless high speed service in mobility scenarios will be
extremely challenging. Our results thus cast doubt on whether outdoor mm-wave
cellular deployments will be feasible in practice, given the high network
control overhead of meeting such stringent beamsteering requirements.


title: Noncommutative discriminants via Poisson primes

abstract:
  We present a general method for computing discriminants of noncommutative
algebras. It builds a connection with Poisson geometry and expresses the
discriminants as products of Poisson primes. The method is applicable to
algebras obtained by specialization from families, such as quantum algebras at
roots of unity. It is illustrated with the specializations of the algebras of
quantum matrices at roots of unity and more generally all quantum Schubert cell
algebras.


title: Wilson Loops and Chiral Correlators on Squashed Spheres

abstract:
  After a very brief recollection of how my scientific collaboration with Ugo
started, in this talk I will present some recent results obtained with
localization: the deformed gauge theory partition function $Z(\vec\tau|q)$ and
the expectation value of circular Wilson loops $W$ on a squashed four-sphere
will be computed. The partition function is deformed by turning on $\tau_J
\,{\rm tr} \, \Phi^J$ interactions with $\Phi$ the ${\cal N}=2$ superfield.
  For the ${\cal N}=4$ theory SUSY gauge theory exact formulae for $Z$ and $W$
in terms of an underlying $U(N)$ interacting matrix model can be derived thus
replacing the free Gaussian model describing the undeformed ${\cal N}=4$
theory. These results will be then compared with those obtained with the dual
CFT according to the AGT correspondence. The interactions introduced previously
are in fact related to the insertions of commuting integrals of motion in the
four-point CFT correlator and the chiral correlators are expressed as
$\tau$-derivatives of the gauge theory partition function on a finite
$\Omega$-background.


title:
Ground-based near-UV observations of 15 transiting exoplanets:
  Constraints on their atmospheres and no evidence for asymmetrical transits

abstract:
  Transits of exoplanets observed in the near-UV have been used to study the
scattering properties of their atmospheres and possible star-planet
interactions. We observed the primary transits of 15 exoplanets (CoRoT-1b,
GJ436b, HAT-P-1b, HAT-P-13b, HAT-P-16b, HAT-P-22b, TrES-2b, TrES-4b, WASP-1b,
WASP-12b, WASP-33b, WASP-36b, WASP-44b, WASP-48b, and WASP-77Ab) in the near-UV
and several optical photometric bands to update their planetary parameters,
ephemerides, search for a wavelength dependence in their transit depths to
constrain their atmospheres, and determine if asymmetries are visible in their
light curves. Here we present the first ground-based near-UV light curves for
12 of the targets (CoRoT-1b, GJ436b, HAT-P-1b, HAT-P-13b, HAT-P-22b, TrES-2b,
TrES-4b, WASP-1b, WASP-33b, WASP-36b, WASP-48b, and WASP-77Ab). We find that
none of the near-UV transits exhibit any non-spherical asymmetries, this result
is consistent with recent theoretical predictions by Ben-Jaffel et al. and
Turner et al. The multi-wavelength photometry indicates a constant transit
depth from near-UV to optical wavelengths in 10 targets (suggestive of clouds),
and a varying transit depth with wavelength in 5 targets (hinting at Rayleigh
or aerosol scattering in their atmospheres). We also present the first
detection of a smaller near-UV transit depth than that measured in the optical
in WASP-1b and a possible opacity source that can cause such radius variations
is currently unknown. WASP-36b also exhibits a smaller near-UV transit depth at
2.6$\sigma$. Further observations are encouraged to confirm the transit depth
variations seen in this study.


title: Factorization of Chiral String Amplitudes

abstract:
  We re-examine a closed-string model defined by altering the boundary
conditions for one handedness of two-dimensional propagators in
otherwise-standard string theory. We evaluate the amplitudes using
Kawai-Lewellen-Tye factorization into open-string amplitudes. The only
modification to standard string theory is effectively that the spacetime
Minkowski metric changes overall sign in one open-string factor. This cancels
all but a finite number of states: As found in earlier approaches, with enough
supersymmetry (e.g., type II) the tree amplitudes reproduce those of the
massless truncation of ordinary string theory. However, we now find for the
other cases that additional fields, formerly thought to be auxiliary, describe
new spin-2 states at the two adjacent mass levels (tachyonic and tardyonic).
The tachyon is always a ghost, but can be avoided in the heterotic case.


title: Applications of Information Theory: Statistics and Statistical Mechanics

abstract:
  The method of optimizing entropy is used to (i) conduct Asymptotic Hypothesis
Testing and (ii) determine the particle distribution for which Entropy is
maximized. This paper focuses on two related applications of Information
Theory: Statistics and Statistical Mechanics.


title: Clustering and the Search for Dim and Dark Galaxies

abstract:
  We re-investigate the question of whether there is a significant population
of Dim (Low Surface Brightness) and/or Dark Galaxies (DDGs). We argue that if
they are clustered with bright ones then a physical resolution of ~10 kpc. will
be needed to to distinguish their 21-cm. and QSO Absorption Line(QSOAL)
counterparts from their brighter neighbours, leading to a real possibility of
confusion. But until now such a resolution has not been available in this
context. New Very Large Array (VLA) observations reveal that the
identifications with bright optical objects claimed in previous single-dish
blind HI surveys are often unreliable. For instance 14/36 of our
high-resolution (5 arc sec, 13kpc.) sample have no optical counterparts in the
Digital Sky Survey. This suggests that DDGs might be commonplace after all, and
we go on to re-examine the main arguments that have been used against them.. We
find that the QSOAL argument founders on the aforementioned clustering while
deep CCD surveys have so far covered too small an area to set set strong
constraints on Low Surface Brightness Galaxies (LSBGs). A cosmos filled with
low surface brightness galaxies, dark galaxies and intergalactic gas clouds is
therefore possible.


title:
Spin-wave thermal population as temperature probe in Magnetic Tunnel
  Junctions

abstract:
  We study whether a direct measurement of the absolute temperature of a
Magnetic Tunnel Junction (MTJ) can be performed using the high frequency
electrical noise that it delivers under a finite voltage bias. Our method
includes quasi-static hysteresis loop measurements of the MTJ, together with
the field-dependence of its spin wave noise spectra. We rely on an analytical
modeling of the spectra by assuming independent fluctuations of the different
sub-systems of the tunnel junction that are described as macrospin fluctuators.
We illustrate our method on perpendicularly magnetized MgO-based MTJs patterned
in 50*100 nm2 nanopillars. We apply hard axis (in-plane) fields to let the
magnetic thermal fluctuations yield finite conductance fluctuations of the MTJ.
Instead of the free layer fluctuations that are observed to be affected by both
spin-torque and temperature, we use the magnetization fluctuations of the sole
reference layers. Their much stronger anisotropy and their much heavier damping
render them essentially immune to spin-torque. We illustrate our method by
determining current-induced heating of the perpendicularly magnetized tunnel
junction at voltages similar to those used in spin-torque memory applications.
The absolute temperature can be deduced with a precision of +/- 60 K and we can
exclude any substantial heating at the spin-torque switching voltage.


title:
Rewriting in higher dimensional linear categories and application to the
  affine oriented Brauer category

abstract:
  In this paper, we introduce a rewriting theory of linear monoidal categories.
Those categories are a particular case of what we will define as linear (n,
p)-categories. We will also define linear (n, p)-polygraphs, a linear adapation
of n-polygraphs, to present linear (n -- 1, p)-categories. We focus then on
linear (3, 2)-polygraphs to give presentations of linear monoidal categories.
We finally give an application of this theory in linear (3, 2)-polygraphs to
prove a basis theorem on the category AOB with a new method using a rewriting
property defined by van Ostroom: decreasingness.


title:
The sequence to hydrogenate coronene cations: A journey guided by magic
  numbers

abstract:
  The understanding of hydrogen attachment to carbonaceous surfaces is
essential to a wide variety of research fields and technologies such as
hydrogen storage for transportation, precise localization of hydrogen in
electronic devices and the formation of cosmic H2. For coronene cations as
prototypical Polycyclic Aromatic Hydrocarbon (PAH) molecules, the existence of
magic numbers upon hydrogenation was uncovered experimentally. Quantum
chemistry calculations show that hydrogenation follows a site-specific sequence
leading to the appearance of cations having 5, 11, or 17 hydrogen atoms
attached, exactly the magic numbers found in the experiments. For these
closed-shell cations, further hydrogenation requires appreciable structural
changes associated with a high transition barrier. Controlling specific
hydrogenation pathways would provide the possibility to tune the location of
hydrogen attachment and the stability of the system. The sequence to
hydrogenate PAHs, leading to PAHs with magic numbers of H atoms attached,
provides clues to understand that carbon in space is mostly aromatic and
partially aliphatic in PAHs. PAH hydrogenation is fundamental to assess the
contribution of PAHs to the formation of cosmic H2.


title: Co-adjoint polynomial

abstract:
  In this note we study a certain graph polynomial arising from a special
recursion. This recursion is a member of a family of four recursions where the
other three recursions belong to the chromatic polynomial, the modified
matching polynomial, and the adjoint polynomial, respectively. The four
polynomials share many common properties, for instance all of them are of
exponential type, i. e., they satisfy the identity $$\sum_{S\subseteq
V(G)}f(G[S],x)f(G[V\setminus S],y)=f(G,x+y)$$ for every graph $G$.
  It turns out that the new graph polynomial is a specialization of the Tutte
polynomial.


title:
Connection between MP and DPP for Stochastic Recursive Optimal Control
  Problems: Viscosity Solution Framework in General Case

abstract:
  This paper deals with a stochastic recursive optimal control problem, where
the diffusion coefficient depends on the control variable and the control
domain is not necessarily convex. We focus on the connection between the
general maximum principle and the dynamic programming principle for such
control problem without the assumption that the value is smooth enough, the set
inclusions among the sub- and super-jets of the value function and the
first-order and second-order adjoint processes as well as the generalized
Hamiltonian function are established. Moreover, by comparing these results with
the classical ones in Yong and Zhou [{\em Stochastic Controls: Hamiltonian
Systems and HJB Equations, Springer-Verlag, New York, 1999}], it is natural to
obtain the first- and second-order adjoint equations of Hu [{\em Direct method
on stochastic maximum principle for optimization with recursive utilities,
arXiv:1507.03567v1 [math.OC], 13 Jul. 2015}].


title:
Connection between MP and DPP for Stochastic Recursive Optimal Control
  Problems: Viscosity Solution Framework in Local Case

abstract:
  This paper deals with a nonsmooth version of the connection between the
maximum principle and dynamic programming principle, for the stochastic
recursive control problem when the control domain is convex. By employing the
notions of sub- and super-jets, the set inclusions are derived among the value
function and the adjoint processes. The general case for non-convex control
domain is open.


title: Prediction of Infinite Words with Automata

abstract:
  In the classic problem of sequence prediction, a predictor receives a
sequence of values from an emitter and tries to guess the next value before it
appears. The predictor masters the emitter if there is a point after which all
of the predictor's guesses are correct. In this paper we consider the case in
which the predictor is an automaton and the emitted values are drawn from a
finite set; i.e., the emitted sequence is an infinite word. We examine the
predictive capabilities of finite automata, pushdown automata, stack automata
(a generalization of pushdown automata), and multihead finite automata. We
relate our predicting automata to purely periodic words, ultimately periodic
words, and multilinear words, describing novel prediction algorithms for
mastering these sequences.


title: Point-contact spectra of $2H-NbS{{e}_{2}}$ in the superconducting state

abstract:
  A qualitative study of the electron-phonon interaction (EPI) spectra in
$2H-NbS{{e}_{2}}$ is carried out by the method of point-contact spectroscopy in
the superconducting state. Anisotropy of the EPI spectra for contacts oriented
in the principal crystallographic directions (along the $c$ axis and parallel
to the basal surface) was observed. Approximate values of the positions of the
main features in the phonon density of states were established for both
directions. The additional low-frequency peaks observed in the spectra for
separate crystallographic orientations are associated with the collective
oscillations of the amplitude and phase of charge density waves.


title: Alperin's Fusion Theorem for localities

abstract: In these notes we give an Alperin's Fusion Theorem for localities.


title:
The link between rare earth peak formation and the astrophysical site of
  the $r$ process

abstract:
  The primary astrophysical source of the rare earth elements is the rapid
neutron capture process ($r$ process). The rare earth peak that is seen in the
solar $r$-process residuals has been proposed to originate as a pile-up of
nuclei during the end of the $r$ process. We introduce a new method utilizing
Monte Carlo studies of nuclear masses in the rare earth region, that includes
self-consistently adjusting $\beta$-decay rates and neutron capture rates, to
find the mass surfaces necessary for the formation of the rare earth peak. We
demonstrate our method with two types of astrophysical scenarios, one
corresponding conditions typical of core-collapse supernova winds and one
corresponding to conditions typical of the ejection of the material from the
tidal tails of neutron star mergers. In each type of astrophysical conditions,
this method successfully locates a region of enhanced stability in the mass
surface that is responsible for the rare earth peak. For each scenario, we find
that the change in the mass surface has qualitatively different features, thus
future measurements can shed light on the type of environment in which the $r$
process occurred.


title:
Layered frustrated antiferromagnetic Heisenberg spin model: role of
  inplane frustration and interlayer coupling

abstract:
  We present an exact diagonalization study on layered $J_{1}-J_{2}$
antiferromagnetic Heisenberg spin model to examine the role of frustration
induced by inplane next-nearest neighbor coupling $J_{2}$, in presence of
interlayer antiferromagnetic coupling $J_{\perp}$. A finite lattice of 24 spins
in layered geometry of $(4\times 3)\oplus (4\times 3)$ is considered and the
resulting Hamiltonian matrix diagonalized using Davidson iterative algorithm to
obtain the ground and a few low-lying excited states. The lattice size ($24$
spins with Hilbert space dimensionality of $2704156$ in $S_{z}^{tot}=0$
subspace) has been kept relatively small because of the large number of runs
required to sample $J_{1}-J_{2}-J_{\perp}$ parameter space. Quantities like
spin-gap, Shannon entropy, spin-spin correlation, static spin structure-factor,
magnetic specific-heat and magnetic susceptibility are calculated for various
values of spin-spin coupling parameters. With increase in interlayer coupling,
the system is driven to states with long range order and the interval of
quantum paramagnetically disordered state, sandwiched between N\'{e}el and
collinear ordered states, narrows on the scale of inplane frustration
parameter.


title: Phase transitions in Thirring's model

abstract:
  In his pioneering work on negative specific heat, Walter Thirring
in\-tro\-duced a model that is solvable in the microcanonical ensemble. Here,
we give a complete description of the phase-diagram of this model in both the
microcanonical and the canonical ensemble, highlighting the main features of
ensemble inequivalence. In both ensembles, we find a line of first-order phase
transitions which ends in a critical point. However, neither the line nor the
point have the same location in the phase-diagram of the two ensembles. We also
show that the microcanonical and canonical critical points can be analytically
related to each other using a Landau expansion of entropy and free energy,
respectively, in analogy with what has been done in [O. Cohen, D. Mukamel, J.
Stat. Mech., P12017 (2012)]. Examples of systems with certain symmetries
restricting the Landau expansion have been considered in this reference, while
no such restrictions are present in Thirring's model. This leads to a phase
diagram that can be seen as a prototype for what happens in systems of
particles with kinematic degrees of freedom dominated by long-range
interactions.


title:
The hole Fermi surface in Bi$_{2}$Se$_{3}$ probed by quantum
  oscillations

abstract:
  Transport and torque magnetometry measurements are performed at high magnetic
fields and low temperatures in a series of p-type (Ca-doped) Bi$_{2}$Se$_{3}$
crystals. The angular dependence of the Shubnikov-de Haas and de Haas-van
Alphen quantum oscillations enables us to determine the Fermi surface of the
bulk valence band states as a function of the carrier density. At low density,
the angular dependence exhibits a downturn in the oscillations frequency
between $0^\circ$ and $90^\circ$, reflecting a bag-shaped hole Fermi surface.
The detection of a single frequency for all tilt angles rules out the existence
of a Fermi surface with different extremal cross-sections down to $24$~meV.
There is therefore no signature of a camel-back in the valence band of our bulk
samples, in accordance with the direct band gap predicted by $GW$ calculations.


title: Observing Trends in Automated Multilingual Media Analysis

abstract:
  Any large organisation, be it public or private, monitors the media for
information to keep abreast of developments in their field of interest, and
usually also to become aware of positive or negative opinions expressed towards
them. At least for the written media, computer programs have become very
efficient at helping the human analysts significantly in their monitoring task
by gathering media reports, analysing them, detecting trends and - in some
cases - even to issue early warnings or to make predictions of likely future
developments. We present here trend recognition-related functionality of the
Europe Media Monitor (EMM) system, which was developed by the European
Commission's Joint Research Centre (JRC) for public administrations in the
European Union (EU) and beyond. EMM performs large-scale media analysis in up
to seventy languages and recognises various types of trends, some of them
combining information from news articles written in different languages and
from social media posts. EMM also lets users explore the huge amount of
multilingual media data through interactive maps and graphs, allowing them to
examine the data from various view points and according to multiple criteria. A
lot of EMM's functionality is accessibly freely over the internet or via apps
for hand-held devices.


title: Sums of read-once formulas: How many summands suffice?

abstract:
  An arithmetic read-once formula (ROF) is a formula (circuit of fan-out 1)
over $+,\times$ where each variable labels at most one leaf. Every multilinear
polynomial can be expressed as the sum of ROFs. In this work, we prove, for
certain multilinear polynomials, a tight lower bound on the number of summands
in such an expression.


title: Information Gain on Reheating: the One Bit Milestone

abstract:
  We show that the Planck 2015 and BICEP2/KECK measurements of the Cosmic
Microwave Background (CMB) anisotropies provide together an information gain of
0.82 +- 0.13 bits on the reheating history over all slow-roll single-field
models of inflation. This corresponds to a 40% improvement compared to the
Planck 2013 constraints on the reheating. Our method relies on an exhaustive
CMB data analysis performed over nearly 200 models of inflation to derive the
Kullback-Leibler entropy between the prior and the fully marginalized posterior
of the reheating parameter. This number is a weighted average by the Bayesian
evidence of each model to explain the data thereby ensuring its fairness and
robustness.


title:
The post-outburst pulsations of the accreting white dwarf in the
  cataclysmic variable GW Librae

abstract:
  We present new time-series photometry of the accreting pulsating white dwarf
system GW Librae obtained in 2012 and 2013 at the University of Canterbury Mt
John Observatory in New Zealand. Our 2012 data show the return of a $\sim$19
minute periodicity that was previously detected in 2008. This pulsation mode
was a dominant feature of our quality May 2012 data set, which consisted of six
contiguous nights; a detailed analysis indicated a degree of frequency
variability. We show by comparison with the previously identified pulsation
modes that this periodicity is best explained as a new mode, and that the
quasi-stability of the periods appears to be a general feature of the
pulsations in these systems. We also find a previously unreported 3-hour
modulation period, which we believe to be related to the known two and four
hour periods of so far unknown origin.


title: Thermal transport in crystals as a kinetic theory of relaxons

abstract:
  Thermal conductivity in dielectric crystals is the result of the relaxation
of lattice vibrations described by the phonon Boltzmann transport equation.
Remarkably, an exact microscopic definition of the heat carriers and their
relaxation times is still missing: phonons, typically regarded as the relevant
excitations for thermal transport, cannot be identified as the heat carriers
when most scattering events conserve momentum and do not dissipate heat flux.
This is the case for two-dimensional or layered materials at room temperature,
or three-dimensional crystals at cryogenic temperatures. In this work we show
that the eigenvectors of the scattering matrix in the Boltzmann equation define
collective phonon excitations, termed here relaxons. These excitations have
well defined relaxation times, directly related to heat flux dissipation, and
provide an exact description of thermal transport as a kinetic theory of the
relaxon gas. We show why Matthiessen's rule is violated, and construct a
procedure for obtaining the mean free paths and relaxation times of the
relaxons. These considerations are general, and would apply also to other
semiclassical transport models, such as the electronic Boltzmann equation. For
heat transport, they remain relevant even in conventional crystals like
silicon, but are of the utmost importance in the case of two-dimensional
materials, where they can revise by several orders of magnitude the relevant
time- and length-scales for thermal transport in the hydrodynamic regime.


title: Interactive Modeling of Concept Drift and Errors in Relevance Feedback

abstract:
  Users giving relevance feedback in exploratory search are often uncertain
about the correctness of their feedback, which may result in noisy or even
erroneous feedback. Additionally, the search intent of the user may be volatile
as the user is constantly learning and reformulating her search hypotheses
during the search. This may lead to a noticeable concept drift in the feedback.
We formulate a Bayesian regression model for predicting the accuracy of each
individual user feedback and thus find outliers in the feedback data set.
Additionally, we introduce a timeline interface that visualizes the feedback
history to the user and gives her suggestions on which past feedback is likely
in need of adjustment. This interface also allows the user to adjust the
feedback accuracy inferences made by the model. Simulation experiments
demonstrate that the performance of the new user model outperforms a simpler
baseline and that the performance approaches that of an oracle, given a small
amount of additional user interaction. A user study shows that the proposed
modelling technique, combined with the timeline interface, makes it easier for
the users to notice and correct mistakes in their feedback, and to discover new
items.


title: Wave packet dynamics in the optimal superadiabatic approximation

abstract:
  We explain the concept of superadiabatic approximations and show how in the
context of the Born- Oppenheimer approximation they lead to an explicit formula
that can be used to predict transitions at avoided crossings. Based on this
formula, we present a simple method for computing wave packet dynamics across
avoided crossings. Only knowledge of the adiabatic electronic energy levels
near the avoided crossing is required for the computation. In particular, this
means that no diabatization procedure is necessary, the adiabatic energy levels
can be computed on the fly, and they only need to be computed to higher
accuracy when an avoided crossing is detected. We test the quality of our
method on the paradigmatic example of photo-dissociation of NaI, finding very
good agreement with results of exact wave packet calculations.


title: Scheduling meets n-fold Integer Programming

abstract:
  Scheduling problems are fundamental in combinatorial optimization. Much work
has been done on approximation algorithms for NP-hard cases, but relatively
little is known about exact solutions when some part of the input is a fixed
parameter. In 2014, Mnich and Wiese initiated a systematic study in this
direction.
  In this paper we continue this study and show that several additional cases
of fundamental scheduling problems are fixed parameter tractable for some
natural parameters. Our main tool is n-fold integer programming, a recent
variable dimension technique which we believe to be highly relevant for the
parameterized complexity community. This paper serves to showcase and highlight
this technique.
  Specifically, we show the following four scheduling problems to be
fixed-parameter tractable, where p max is the maximum processing time of a job
and w max is the maximum weight of a job:
  - Makespan minimization on uniformly related machines $(Q||C_{max} )$
parameterized by $p_{max}$,
  - Makespan minimization on unrelated machines $(R||C_{max} )$ parameterized
by $p_{max}$ and the number of kinds of machines,
  - Sum of weighted completion times minimization on unrelated machines $(R||
\sum w_i C_i )$ parameterized by $p_{max} + w_{max}$ and the number of kinds of
machines,
  - The same problem, $(R|| \sum w_i C_i),$ parameterized by the number of
distinct job times and the number of machines.


title: Phase nucleation in curved space

abstract:
  Nucleation and growth is the dominant relaxation mechanism driving first
order phase transitions. In two-dimensional at systems nucleation has been
applied to a wide range of problems in physics, chemistry and biology. Here we
study nucleation and growth of two-dimensional phases lying on curved surfaces
and show that curvature modify both, critical sizes of nuclei and paths towards
the equilibrium phase. In curved space nucleation and growth becomes inherently
inhomogeneous and critical nuclei form faster on regions of positive Gaussian
curvature. Substrates of varying shape display complex energy landscapes with
several geometry-induced local minima, where initially propagating nuclei
become stabilized and trapped by the underlying curvature.


title:
Network-wide Packet Behavior Identification and Private Network Function
  Outsourcing

abstract:
  Identifying the network-wide forwarding behaviors of a packet is essential
for many network management applications. We present AP Classifier, a control
plane tool for packet be- havior identification. Experiments show that the
processing speed of AP Classifier is faster than existing tools by at least an
order of magnitude. Furthermore, AP Classifier uses very small memory and is
able to support real-time updates. We also present a network function outsource
framework with AP Classifier which can provide security properties.


title: Structured Topological Field Theories via Crossed Simplicial Groups

abstract:
  We show how the framework of crossed simplicial groups may be used to provide
a classification of topological field theories on open cobordism categories
defined by reductions of the structure group to a planar Lie group. Such
theories are equivalent to algebras equipped with a group action and a
non-degenerate trace satisfying certain invariance requirements which
generalize the notion of a frobenius algebra.


title: Unbiased estimation of risk

abstract:
  The estimation of risk measures recently gained a lot of attention, partly
because of the backtesting issues of expected shortfall related to
elicitability. In this work we shed a new and fundamental light on optimal
estimation procedures of risk measures in terms of bias. We show that once the
parameters of a model need to be estimated, one has to take additional care
when estimating risks. The typical plug-in approach, for example, introduces a
bias which leads to a systematic underestimation of risk. In this regard, we
introduce a novel notion of unbiasedness to the estimation of risk which is
motivated by economic principles. In general, the proposed concept does not
coincide with the well-known statistical notion of unbiasedness. We show that
an appropriate bias correction is available for many well-known estimators. In
particular, we consider value-at-risk and expected shortfall (tail
value-at-risk). In the special case of normal distributions, closed-formed
solutions for unbiased estimators can be obtained. We present a number of
motivating examples which show the outperformance of unbiased estimators in
many circumstances. The unbiasedness has a direct impact on backtesting and
therefore adds a further viewpoint to established statistical properties.


title:
Bound and scattering states in harmonic waveguides in the vicinity of
  free space Feshbach resonances

abstract:
  The two-body bound and scattering properties in an one-dimensional harmonic
waveguide close to free space magnetic Feshbach resonances are investigated
based on the local frame transformation approach within a single partial wave
approximation. An energy and magnetic field dependent free space phase shift is
adopted in the current theoretical framework. For both $s$- and $p$-wave
interaction, the least bound state in the waveguide dissociates into the
continuum at the resonant magnetic field where the effective one-dimensional
scattering length $a_{\rm 1D}$ diverges. Consequently, the association of atoms
into molecules in the waveguide occurs when the magnetic field is swept
adiabatically across the pole of $a_{\rm 1D}$. In the vicinity of broad
$s$-wave resonances, the resonant magnetic field is nearly independent on the
transverse confining frequency $\omega_{\perp}$ of the waveguide. Close to
$p$-wave and narrow $s$-wave resonances, the resonant magnetic field changes as
$\omega_{\perp}$ varies.


title:
Iterative Hough Forest with Histogram of Control Points for 6 DoF Object
  Registration from Depth Images

abstract:
  State-of-the-art techniques proposed for 6D object pose recovery depend on
occlusion-free point clouds to accurately register objects in 3D space. To
reduce this dependency, we introduce a novel architecture called Iterative
Hough Forest with Histogram of Control Points that is capable of estimating
occluded and cluttered objects' 6D pose given a candidate 2D bounding box. Our
Iterative Hough Forest is learnt using patches extracted only from the positive
samples. These patches are represented with Histogram of Control Points (HoCP),
a "scale-variant" implicit volumetric description, which we derive from
recently introduced Implicit B-Splines (IBS). The rich discriminative
information provided by this scale-variance is leveraged during inference,
where the initial pose estimation of the object is iteratively refined based on
more discriminative control points by using our Iterative Hough Forest. We
conduct experiments on several test objects of a publicly available dataset to
test our architecture and to compare with the state-of-the-art.


title:
The red one!: On learning to refer to things based on their
  discriminative properties

abstract:
  As a first step towards agents learning to communicate about their visual
environment, we propose a system that, given visual representations of a
referent (cat) and a context (sofa), identifies their discriminative
attributes, i.e., properties that distinguish them (has_tail). Moreover,
despite the lack of direct supervision at the attribute level, the model learns
to assign plausible attributes to objects (sofa-has_cushion). Finally, we
present a preliminary experiment confirming the referential success of the
predicted discriminative attributes.


title:
Band Alignment of 2D Semiconductors for Designing Heterostructures with
  Momentum Space Matching

abstract:
  We present a comprehensive study of the band alignments of two-dimensional
(2D) semiconducting materials and highlight the possibilities of forming
momentum-matched type I, II and III heterojunctions; an enticing possibility
being atomic heterostructures where the constituent monolayers have band edges
at the zone center. Our study, which includes the Group IV and III-V compound
monolayer materials, Group V elemental monolayer materials, transition metal
dichalcogenides (TMD) and transition metal trichalcogenides (TMT) reveals that
almost half of these materials have conduction and/or valence band edges
residing at the zone center. Using first-principles density functional
calculations, we present the type of the heterojunction for 903 different
possible combination of these 2D materials which establishes a periodic table
of heterojunctions.


title: Noise control in gene regulatory networks with negative feedback

abstract:
  Genes and proteins regulate cellular functions through complex circuits of
biochemical reactions. Fluctuations in the components of these regulatory
networks result in noise that invariably corrupts the signal, possibly
compromising function. Here, we create a practical formalism based on ideas
introduced by Wiener and Kolmogorov (WK) for filtering noise in engineered
communications systems to quantitatively assess the extent to which noise can
be controlled in biological processes involving negative feedback. Application
of the theory, which reproduces the previously proven scaling of the lower
bound for noise suppression in terms of the number of signaling events, shows
that a tetracycline repressor-based negative-regulatory gene circuit behaves as
a WK filter. For the class of Hill-like nonlinear regulatory functions, this
type of filter provides the optimal reduction in noise. Our theoretical
approach can be readily combined with experimental measurements of response
functions in a wide variety of genetic circuits, to elucidate the general
principles by which biological networks minimize noise.


title: Zero entropy is generic

abstract:
  Dan Rudolph showed that for an amenable group $\Gamma$, the generic
measure-preserving action of $\Gamma$ on a Lebesgue space has zero entropy.
Here this is extended to nonamenable groups. In fact, the proof shows that
every action is a factor of a zero entropy action! This uses the strange
phenomena that in the presence of nonamenability, entropy can increase under a
factor map. The proof uses Seward's recent generalization of Sinai's Factor
Theorem, the Gaboriau-Lyons result and my theorem that for every nonabelian
free group, all Bernoulli shifts factor onto each other.


title:
Dynamics and protection of entanglement in n-qubit systems within
  Markovian and non-Markovian environments

abstract:
  We provide an analytical investigation of the pairwise entanglement dynamics
for a system, consisting an arbitrary number of qubits dissipating into a
common and non-Markovian environment for both weak and strong coupling regimes.
In the latter case, a revival of pairwise entanglement due to the memory depth
of the environment is observed. The leakage of photons into a continuum state
is assumed to be the source of dissipation. We show that for an initially
Werner state, the environment washes out the pairwise entanglement, but a
series of non-selective measurements can protect the relevant entanglement. On
the other hand, by limiting the number of qubits initially in the superposition
of single excitation, a stationary entanglement can be created between qubits
initially in the excited and ground states. Finally, we determine the
stationary distribution of the entanglement versus the total number of qubits
in the system.


title: Maximum efficiency of steady-state heat engines at arbitrary power

abstract:
  We discuss the efficiency of a heat engine operating in a nonequilibrium
steady state maintained by two heat reservoirs. Within the general framework of
linear irreversible thermodynamics we derive a universal upper bound on the
efficiency of the engine operating at arbitrary fixed power. Furthermore, we
show that a slight decrease of the power below its maximal value can lead to a
significant gain in efficiency. The presented analysis yields the exact
expression for this gain and the corresponding upper bound.


title: Negative magnetoresistivity in holography

abstract:
  Negative magnetoresistivity is a special magnetotransport property associated
with chiral anomaly in four dimensional chiral anomalous systems, which refers
to the transport behavior that the DC longitudinal magnetoresistivity decreases
with increasing magnetic field. We calculate the longitudinal
magnetoconductivity in the presence of backreactions of the magnetic field to
gravity in holographic zero charge and axial charge density systems with and
without axial charge dissipation. In the absence of axial charge dissipation,
we find that the quantum critical conductivity grows with increasing magnetic
field when the backreaction strength is larger than a critical value, in
contrast to the monotonically decreasing behavior of quantum critical
conductivity in the probe limit. With axial charge dissipation, we find the
negative magnetoresistivity behavior. The DC longitudinal magnetoconductivity
scales as $B$ in the large magnetic field limit, which deviates from the exact
$B^2$ scaling of the probe limit result. In both cases, the small frequency
longitudinal magnetoconductivity still agrees with the formula obtained from
the hydrodynamic linear response theory, even in the large magnetic field
limit.


title:
On the Asymptotic Normality of Estimating the Affine Preferential
  Attachment Network Models with Random Initial Degrees

abstract:
  We consider the estimation of the affine parameter (and power-law exponent)
in the preferential attachment model with random initial degrees. We derive the
likelihood, and show that the maximum likelihood estimator (MLE) is
asymptotically normal and efficient. We also propose a quasi-maximum-likelihood
estimator (QMLE) to overcome the MLE's dependence on the history of the initial
degrees. To demonstrate the power of our idea, we present numerical
simulations.


title:
UTA-poly and UTA-splines: additive value functions with polynomial
  marginals

abstract:
  Additive utility function models are widely used in multiple criteria
decision analysis. In such models, a numerical value is associated to each
alternative involved in the decision problem. It is computed by aggregating the
scores of the alternative on the different criteria of the decision problem.
The score of an alternative is determined by a marginal value function that
evolves monotonically as a function of the performance of the alternative on
this criterion. Determining the shape of the marginals is not easy for a
decision maker. It is easier for him/her to make statements such as
"alternative $a$ is preferred to $b$". In order to help the decision maker, UTA
disaggregation procedures use linear programming to approximate the marginals
by piecewise linear functions based only on such statements. In this paper, we
propose to infer polynomials and splines instead of piecewise linear functions
for the marginals. In this aim, we use semidefinite programming instead of
linear programming. We illustrate this new elicitation method and present some
experimental results.


title:
Isospin Mixing Reveals $^{30}$P($p,\gamma$)$^{31}$S Resonance
  Influencing Nova Nucleosynthesis

abstract:
  The thermonuclear $^{30}$P($p,\gamma$)$^{31}$S reaction rate is critical for
modeling the final elemental and isotopic abundances of ONe nova
nucleosynthesis, which affect the calibration of proposed nova thermometers and
the identification of presolar nova grains, respectively. Unfortunately, the
rate of this reaction is essentially unconstrained experimentally, because the
strengths of key $^{31}$S proton capture resonance states are not known,
largely due to uncertainties in their spins and parities. Using the $\beta$
decay of $^{31}$Cl, we have observed the $\beta$-delayed $\gamma$ decay of a
$^{31}$S state at $E_x = 6390.2(7)$ keV, with a $^{30}$P($p,\gamma$)$^{31}$S
resonance energy of $E_r = 259.3(8)$ keV, in the middle of the
$^{30}$P($p,\gamma$)$^{31}$S Gamow window for peak nova temperatures. This
state exhibits isospin mixing with the nearby isobaric analog state (IAS) at
$E_x = 6279.0(6)$ keV, giving it an unambiguous spin and parity of $3/2^+$ and
making it an important $l = 0$ resonance for proton capture on $^{30}$P.


title: Preheating in an Asymptotically Safe Quantum Field Theory

abstract:
  We consider reheating in a class of asymptotically safe quantum field
theories recently studied in \cite{Litim:2014uca, Litim:2015iea}. These
theories allow for an inflationary phase in the very early universe. Inflation
ends with a period of reheating. Since the models contain many scalar fields
which are intrinsically coupled to the inflaton there is the possibility of
parametric resonance instability in the production of these fields, and the
danger that the induced curvature fluctuations will become too large. Here we
show that the parametric instability indeed arises, and that hence the energy
transfer from the inflaton condensate to fluctuating fields is rapid. Demanding
that the curvature fluctuations induced by the parametrically amplified entropy
modes do not exceed the upper observational bounds puts a lower bound on the
number of fields which the model of Ref.~\cite{Litim:2014uca, Litim:2015iea}
must contain. This bound also depends on the total number of e-foldings of the
inflationary phase.


title:
Efficient shapes for microswimming: from three-body swimmers to helical
  flagella

abstract:
  We combine a general formulation of microswimmmer equations of motion with a
numerical bead-shell model to calculate the hydrodynamic interactions with the
fluid, from which the swimming speed, power and efficiency are extracted. From
this framework, a generalized Scallop Theorem emerges. The applicability to
arbitrary shapes allows for the optimization of the efficiency with respect to
the swimmer geometry. We apply this scheme to `three-body swimmers' of various
shapes and find that the efficiency is characterized by the single body
friction coefficient in the long-arm regime, while in the short-arm regime the
minimal approachable distance becomes the determining factor. Next, we apply
this scheme to a biologically inspired swimmer that propels itself using a
rotating helical flagellum. Interestingly, we find two distinct optimal shapes,
one of which is fundamentally different from the shapes observed in nature
(e.g. bacteria).