title:
NNLO low-energy constants from flavor-breaking chiral sum rules based on
  hadronic tau-decay data

abstract:
  Using spectral data from non-strange and strange hadronic tau decays,
flavor-breaking chiral sum rules involving the flavor ud and us current-current
two-point functions are constructed and used to determine the SU(3) NNLO
low-energy constant combinations C_{61}^r, C_{12}^r+C_{61}^r+C_{80}^r and
C_{12}^r-C_{61}^r+C_{80}^r. The first of these determinations updates the
results of an earlier analysis by Durr and Kambor, while the latter two are
new. The error on the C_{12}^r+C_{61}^r+C_{80}^r is particularly small.
Comparisons are made to model estimates for these quantities. The role of the
third combination in significantly improving the determination of the NLO
low-energy constant L_{10}^r from NNLO analyses of the flavor ud V-A correlator
is also highlighted.


title:
Testing the Origin of Cosmological Magnetic Fields through the
  Large-Scale Structure Consistency Relations

abstract:
  We study the symmetries of the post-recombination cosmological
magnetohydrodynamical equations which describe the evolution of dark matter,
baryons and magnetic fields in a self-consistent way. This is done both at the
level of fluid equations and of Vlasov-Poisson-Maxwell equations in phase
space. We discuss some consistency relations for the soft limit of the (n +
1)-correlator functions involving magnetic fields and matter overdensities. In
particular, we stress that any violation of such consistency relations at
equal-time would point towards an inflationary origin of the magnetic field.


title:
i-PI: A Python interface for ab initio path integral molecular dynamics
  simulations

abstract:
  Recent developments in path integral methodology have significantly reduced
the computational expense of including quantum mechanical effects in the
nuclear motion in ab initio molecular dynamics simulations. However, the
implementation of these developments requires a considerable programming
effort, which has hindered their adoption. Here we describe i-PI, an interface
written in Python that has been designed to minimise the effort required to
bring state-of-the-art path integral techniques to an electronic structure
program. While it is best suited to first principles calculations and path
integral molecular dynamics, i-PI can also be used to perform classical
molecular dynamics simulations, and can just as easily be interfaced with an
empirical forcefield code. To give just one example of the many potential
applications of the interface, we use it in conjunction with the CP2K
electronic structure package to showcase the importance of nuclear quantum
effects in high pressure water.


title:
Spatial and temporal structures of four financial markets in Greater
  China

abstract:
  We investigate the spatial and temporal structures of four financial markets
in Greater China. In particular, we uncover different characteristics of the
four markets by analyzing the sector and subsector structures which are
detected through the random matrix theory. Meanwhile, we observe that the
Taiwan and Hongkong stock markets show a negative return-volatility
correlation, i.e., the so-called leverage effect. The Shanghai and Shenzhen
stock markets are more complicated. Before the year 2000, the two markets
exhibit a strong positive return-volatility correlation, which is called the
anti-leverage effect. After 2000, however, it gradually changes to the leverage
effect. We also find that the recurrence interval distributions of both the
trading volume volatilities and price volatilities follow a power law behavior,
while the exponents vary among different markets.


title: On robustly asymmetric graphs

abstract:
  O'Donnell, Wright, Wu and Zhou [SODA 2014] introduced the notion of robustly
asymmetric graphs. Roughly speaking, these are graphs in which for every $0 \le
\rho \le 1$, every permutation that permutes a $\rho$ fraction of the vertices
maps a $\Theta(\rho)$ fraction of the edges to non-edges. We show that there
are graphs for which the constant hidden in the $\Theta$ notation is roughly~1.


title: Random walk questions for linear quantum groups

abstract:
  We study the discrete quantum groups $\Gamma$ whose group algebra has an
inner faithful representation of type $\pi:C^*(\Gamma)\to M_K(\mathbb C)$. Such
a representation can be thought of as coming from an embedding $\Gamma\subset
U_K$. Our main result, concerning a certain class of examples of such quantum
groups, is an asymptotic convergence theorem for the random walk on $\Gamma$.
The proof uses various algebraic and probabilistic techniques.


title: A new upper bound for the Dirac operator on hypersurfaces

abstract:
  We prove a new upper bound for the first eigenvalue of the Dirac operator of
a compact hypersurface in any Riemannian spin manifold carrying a non-trivial
twistor spinor without zeros on the hypersurface. The upper bound is expressed
as the first eigenvalue of a drifting Schr\"odinger operator on the
hypersurface. Moreover, using a recent approach developed by O. Hijazi and S.
Montiel, we completely characterize the equality case when the ambient manifold
is the standard hyperbolic space.


title:
Floquet scattering matrix theory of heat fluctuations in dynamical
  quantum conductors

abstract:
  I present the Floquet scattering matrix theory of low-frequency heat
fluctuations in driven multi-terminal quantum-coherent conductors in the linear
response regime and beyond. The intrinsic fluctuations of energy of dynamically
excited electrons are identified as the fundamental source of a heat noise not
revealed by the electrical noise. The role of backscattering in the increase of
a heat noise above the level defined by the Callen-Welton
fluctuation-dissipation theorem, is highlighted.


title: Breaking a monad-comonad symmetry between computational effects

abstract:
  Computational effects may often be interpreted in the Kleisli category of a
monad or in the coKleisli category of a comonad. The duality between monads and
comonads corresponds, in general, to a symmetry between construction and
observation, for instance between raising an exception and looking up a state.
Thanks to the properties of adjunction one may go one step further: the
coKleisli-on-Kleisli category of a monad provides a kind of observation with
respect to a given construction, while dually the Kleisli-on-coKleisli category
of a comonad provides a kind of construction with respect to a given
observation. In the previous examples this gives rise to catching an exception
and updating a state. However, the interpretation of computational effects is
usually based on a category which is not self-dual, like the category of sets.
This leads to a breaking of the monad-comonad duality. For instance, in a
distributive category the state effect has much better properties than the
exception effect. This remark provides a novel point of view on the usual
mechanism for handling exceptions. The aim of this paper is to build an
equational semantics for handling exceptions based on the coKleisli-on-Kleisli
category of the monad of exceptions. We focus on n-ary functions and
conditionals. We propose a programmer's language for exceptions and we prove
that it has the required behaviour with respect to n-ary functions and
conditionals.


title: Optimal Sharing Rule for a Household with a Portfolio Management Problem

abstract:
  We study the Merton problem of optimal consumption-investment for the case of
two investors sharing a final wealth. The typical example would be a husband
and wife sharing a portfolio looking to optimize the expected utility of
consumption and final wealth. Each agent has different utility function and
discount factor. An explicit formulation for the optimal consumptions and
portfolio can be obtained in the case of a complete market. The problem is
shown to be equivalent to maximizing three different utilities separately with
separate initial wealths. We study a numerical example where the market price
of risk is assumed to be mean reverting, and provide insights on the influence
of risk aversion or discount rates on the initial optimal allocation.


title: Nanocrystal energetics via quantum similarity measures

abstract:
  We first develop a descriptor-based representation of atomic environments by
devising two local similarity indices defined from an atom-partitioned
quantum-chemical descriptor. Then, we employ this representation to explore the
size-, shape- and composition-dependent nanocrystal energetics. For this
purpose, we utilize an energy difference {\mu} that is related to the atomic
chemical potential, which enables one to characterize energetic
heterogeneities. Employing first-principles calculations based on the density
functional theory for a set of database systems, namely unary atomic clusters
in the shape of regular polyhedra and the bulk solids of C, Si, Pd and Pt, we
explore the correlations between the energy difference {\mu} and similarity
indices. We find that there exists an interconnection between nanocrystal
energetics and quantum similarity measures. Accordingly, we develop a means for
computing total energy differences from the similarity indices via
interpolation, and utilize a test set comprising a variety of unary
nanocrystals and binary nanoalloys/nanocompounds for validation. Our findings
indicate that the similarity-based energies could be utilized in computer-aided
design of nanoparticles.


title: On Recent Advances in Supervised Ranking for Metabolite Profiling

abstract:
  This paper focuses on data arising from the field of metabolomics, a rapidly
developing area concerned by the analysis of the chemical fingerprints (i.e.
the metabolite profile). The metabolite profile is left by specific chemical
processes occurring in biological cells, tissues or organs. It is the main
purpose of this article to develop and implement scoring techniques so as to
rank all possible metabolic profiles by increasing order of magnitude of the
conditional probability that a given metabolite is present at high levels in a
certain biological fluid. After a detailed description of the (functional) data
from which decision rules must be learnt, several approaches to this predictive
problem, based on recent advances in K-partite ranking are described at length.
Their performance on several real datasets are next thoroughly investigated.


title: Charged Q-balls and boson stars and dynamics of charged test particles

abstract:
  We construct electrically charged Q-balls and boson stars in a model with a
scalar self-interaction potential resulting from gauge mediated supersymmetry
breaking. We discuss the properties of these solutions in detail and emphasize
the differences to the uncharged case. We observe that Q-balls can only be
constructed up to a maximal value of the charge of the scalar field, while for
boson stars the interplay between the attractive gravitational force and the
repulsive electromagnetic force determines their behaviour. We find that the
vacuum is stable with respect to pair production in the presence of our charged
boson stars. We also study the motion of charged, massive test particles in the
space-time of boson stars. We find that in contrast to charged black holes the
motion of charged test particles in charged boson star space-times is planar,
but that the presence of the scalar field plays a crucial role for the
qualitative features of the trajectories. Applications of this test particle
motion can be made in the study of extreme-mass ratio inspirals (EMRIs) as well
as astrophysical plasmas relevant e.g. in the formation of accretion discs and
polar jets of compact objects.


title: Photo-fragmentation spectroscopy of benzylium and 1-phenylethyl cations

abstract:
  The electronic spectra of cold benzylium (C6H5-CH2+) and 1-phenylethyl
(C6H5-CH-CH3+)cations have been recorded via photofragment spectroscopy.
Benzylium and 1-phenylethyl cations produced from electrosprayed benzylamine
and phenylethylamine solutions, respectively, were stored in a cryogenically
cooled quadrupole ion trap and photodissociated by an OPO laser, scanned in
parts of the UV and visible regions (600-225 nm). The electronic states and
active vibrational modes of the benzylium and 1-phenylethyl cations as well as
those of their tropylium or methyl tropylium isomers have been calculated with
ab initio methods for comparison with the spectra observed. Sharp vibrational
progressions are observed in the visible region while the absorption features
are much broader in the UV. The visible spectrum of the benzylium cation is
similar to that obtained in an argon tagging experiment [V. Dryza, N. Chalyavi,
J.A. Sanelli, and E.J. Bieske, J. Chem. Phys. 137, 204304 (2012)], with an
additional splitting assigned to Fermi resonances. The visible spectrum of the
1-phenylethyl cation also shows vibrational progressions. For both cations, the
second electronic transition is observed in the UV, around 33 000 cm-1 (4.1
eV), and shows a broadened vibrational progression. In both cases the S2
optimized geometry is non planar. The third electronic transition observed
around 40 000 cm-1 (5.0 eV) is even broader with no apparent vibrational
structures, which is indicative of either a fast non-radiative process or a
very large change in geometry between the excited and the ground states. The
oscillator strengths calculated for tropylium and methyl tropylium are weak.
Therefore, these isomeric structures are most likely not responsible for these
absorption features. Finally, the fragmentation pattern changes in the second
and third electronic states: C2H2 loss becomes predominant at higher excitation
energies, for both cations.


title: Multiferroic properties of o-LuMnO$_3$ controlled by b-axis strain

abstract:
  Strain is a leading candidate for controlling magnetoelectric coupling in
multiferroics. Here, we use x-ray diffraction to study the coupling between
magnetic order and structural distortion in epitaxial films of the orthorhombic
(o-) perovskite LuMnO$_3$. An antiferromagnetic spin canting in the E-type
magnetic structure is shown to be related to the ferroelectrically induced
structural distortion and to a change in the magnetic propagation vector. By
comparing films of different orientations and thicknesses, these quantities are
found to be controlled by b-axis strain. It is shown that compressive strain
destabilizes the commensurate E-type structure and reduces its accompanying
ferroelectric distortion.


title: Uniaxial symmetry in nematic liquid crystals

abstract:
  Within the Landau-de Gennes theory of liquid crystals, we study theoretically
the equilibrium configurations with uniaxial symmetry. We show that the
uniaxial symmetry constraint is very restrictive and can in general not be
satisfied, except in very symmetric situations. For one- and two-dimensional
configurations, we characterize completely the uniaxial equilibria: they must
have constant director. In the three dimensional case we focus on the model
problem of a spherical droplet with radial anchoring, and show that any
uniaxial equilibrium must be spherically symmetric. It was known before that
uniaxiality can sometimes be broken by energy minimizers. Our results shed a
new light on this phenomenon: we prove here that in one or two dimensions
uniaxial symmetry is always broken, unless the director is constant. Moreover,
our results concern all equilibrium configurations, and not merely energy
minimizers.


title: HCM Property and the Half-Cauchy Distribution

abstract:
  Let $Z_\al$ be a positive $\alpha$-stable random variable and
$T_\al=(Z_\al/\tilde Z_\al)^\al,$ with independents components in the quotient.
It is known that $T_\al$ is distributed as the positive branch of a Cauchy
random variable with drift. We show that the density of the power
transformation $T_\al^\beta$ is hyperbolically completely monotone in the sense
of Thorin and Bondesson if and only if $\al\le1/2$ and $|\beta|\ge 1/(1-\al).$
This clarifies a conjecture of Bondesson (1992) on positive stable densities.


title:
A continuous interpolation between conservative and dissipative
  solutions for the two-component Camassa-Holm system

abstract:
  We introduce a novel solution concept, denoted $\alpha$-dissipative
solutions, that provides a continuous interpolation between conservative and
dissipative solutions of the Cauchy problem for the two-component Camassa-Holm
system on the line with vanishing asymptotics. All the $\alpha$-dissipative
solutions are global weak solutions of the same equation in Eulerian
coordinates, yet they exhibit rather distinct behavior at wave breaking. The
solutions are constructed after a transformation into Lagrangian variables,
where the solution is carefully modified at wave breaking.


title:
Local and global properties of solutions of quasilinear Hamilton-Jacobi
  equations

abstract:
  We study some properties of the solutions of (E) $\;-\Gd_p u+|\nabla u|^q=0$
in a domain $\Gw \sbs \BBR^N$, mostly when $p\geq q>p-1$. We give a universal
priori estimate of the gradient of the solutions with respect to the distance
to the boundary. We give a full classification of the isolated singularities of
the positive solutions of (E), a partial classification of isolated
singularities of the negative solutions. We prove a general removability result
in expressed in terms of some Bessel capacity of the removable set. We extend
our estimates to equations on complete non compact manifolds satisfying a lower
bound estimate on the Ricci curvature, and derive some Liouville type theorems.


title:
New families of subordinators with explicit transition probability
  semigroup

abstract:
  There exist only a few known examples of subordinators for which the
transition probability density can be computed explicitly along side an
expression for its L\'evy measure and Laplace exponent. Such examples are
useful in several areas of applied probability, for example, they are used in
mathematical finance for modeling stochastic time change, they appear in
combinatorial probability to construct sampling formulae, which in turn is
related to a variety of issues in the theory of coalescence models, moreover,
they have also been extensively used in the potential analysis of subordinated
Brownian motion in dimension greater than or equal to 2. In this paper, we show
that Kendall's classic identity for spectrally negative L\'evy processes can be
used to construct new families of subordinators with explicit transition
probability semigroups. We describe the properties of these new subordinators
and emphasise some interesting connections with explicit and previously unknown
Laplace transform identities and with complete monotonicity properties of
certain special functions.


title:
A note on Autoreducibility for Infinite Time Register Machines and
  parameter-free Ordinal Turing Machines

abstract:
  We propose a notion of autoreducibility for infinite time computability and
explore it and its connection with a notion of randomness for infinite time
machines.


title: Markov loops in discrete spaces

abstract:
  The main topic of these notes are Markov loops, studied in the context of
continuous time Markov chains on discrete state spaces. We refer to [1] and [2]
for the short "history" of the subject. In contrast with these references,
symmetry is not assumed, and more attention is given to the infinite case. All
results are presented in terms of the semigroup generator. In comparison with
[1], some delicate proofs are given in more details or with a better method. We
focus mostly on properties of the (multi)occupation field but also included
some results about loop clusters (see [3] in the symmetric context) and
spanning trees.
  [1] Markov paths, loops and fields, by Yves Le Jan, Lecture Notes in
Mathematics, vol. 2026, Springer, Heidelberg, 2011 [2] Topics in occupation
times and Gaussian free fields, by Alain-Sol Sznitman, Zurich Lectures in
Advanced Mathematics, European Mathematical Society (EMS), Z\"urich, 2012 [3]
Markovian loop clusters on graphs, by Yves Le Jan and Sophie Lemaire, Preprint,
arxiv:1211.0300 [math.PR], 2012


title: Spectrum of the semi-relativistic Pauli-Fierz model I

abstract:
  HVZ type theorem for semi-relativistic Pauli-Fierz Hamiltonian,
$$\HHH=\sqrt{(p\otimes \one -A)^2+M^2}+V\otimes \one +\one\otimes \hf,\quad
M\geq 0,$$ in quantum electrodynamics is studied. Here $H$ is a self-adjoint
operator in Hilbert space $\LR\otimes \fff\cong \int^\oplus_{\RR^d}\fff {\rm
d}x$, and $A=\int^\oplus_{\RR^d} A(x) {\rm d}x$ a quantized radiation field and
$\hf$ the free field Hamiltonian defined by the second quantization of a
dispersion relation $\omega:\RR^d\to \RR$. It is emphasized that massless case,
$M=0$, is included. Let $E=\inf \sigma (\HHH)$ be the bottom of the spectrum of
$\HHH$. Suppose that the infimum of $\omega$ is $m>0$. Then it is shown that
$\sigma_{\rm ess}(\HHH)=[E+m, \infty)$. In particular the existence of the
ground state of $\HHH$ can be proven.


title:
\alpha'-Expansion of Open String Disk Integrals via Mellin
  Transformations

abstract:
  Open string disk integrals are represented as contour integrals of a product
of Beta functions by using Mellin transformations. This makes the mathematical
problem of computing the \alpha' expansion around the field theory limit
basically identical to that of the \epsilon expansion in Feymann loop integrals
around the four dimensional limit. More explicitly, the formula in Mellin space
obtained directly from the standard Koba-Nielsen like representation is valid
in a region of values of \alpha' that does not include \alpha'=0. Analytic
continuation is therefore needed since contours are pinched by poles as \alpha'
approaches 0. Deforming contours that get pinched by poles generates a set of
(n-3)! multidimensional residues left behind which contain all the field theory
information. We end by drawing some analogies between the field theory formulas
obtained by this method and those derived recently from using the scattering
equations.


title: Generalised Quantum Waveguides

abstract:
  We study general quantum waveguides and establish explicit effective
Hamiltonians for the Laplacian on these spaces. A conventional quantum
waveguide is an $\varepsilon$-tubular neighbourhood of a curve in
$\mathbb{R}^3$ and the object of interest is the Dirichlet Laplacian on this
tube in the asymptotic limit $\varepsilon\to0$. We generalise this by
considering fibre bundles $M$ over a $d$-dimensional submanifold
$B\subset\mathbb{R}^{d+k}$ with fibres diffeomorphic to $F\subset\mathbb{R}^k$,
whose total space is embedded into an $\varepsilon$-neighbourhood of $B$. From
this point of view $B$ takes the role of the curve and $F$ that of the
disc-shaped cross-section of a conventional quantum waveguide. Our approach
allows, among other things, for waveguides whose cross-sections $F$ are
deformed along $B$ and also the study of the Laplacian on the boundaries of
such waveguides. By applying recent results on the adiabatic limit of
Schr\"odinger operators on fibre bundles we show, in particular, that for small
energies the dynamics and the spectrum of the Laplacian on $M$ are reflected by
the adiabatic approximation associated to the ground state band of the normal
Laplacian. We give explicit formulas for the according effective operator on
$L^2(B)$ in various scenarios, thereby improving and extending many of the
known results on quantum waveguides and quantum layers in $\mathbb{R}^3$.


title: Towards an improved description of SiDIS by a polarized 3He target

abstract:
  The possibility of improving the description of the semi-inclusive deep
inelastic electron scattering off polarized 3He, that provides information on
the neutron single spin asymmetries, is illustrated. In particular, the
analysis at finite momentum transfers in a Poincare' covariant framework is
outlined and a generalized eikonal approach to include final state interaction
is presented.


title:
q,t-characters and the structure of the $\ell$-weight spaces of standard
  modules over simply laced quantum affine algebras

abstract:
  We establish, for all simply laced types, a q,t-character formula, first
conjectured by Nakajima. It relates, on one hand, the structure of the
$\ell$-weight spaces of standard modules regarded as modules over the
Heisenberg subalgebra of some quantum affine algebra and, on the other hand,
the t-dependence of their q,t-characters, as originally defined in terms of the
Poincar\'e polynomials of certain Lagrangian subvarieties in quiver varieties
of the corresponding simply laced type. Our proof is essentially geometric and
generalizes to arbitrary simply laced types earlier representation theoretical
results for standard $\mathrm{U}_q (\widehat{\mathfrak{sl}}_2)$-modules.


title: Generalized squirming motion of a sphere

abstract:
  A number of swimming microorganisms such as ciliates ($\textit{Opalina}$) and
multicellular colonies of flagellates ($\textit{Volvox}$) are approximately
spherical in shape and swim using beating arrays of cilia or short flagella
covering their surfaces. Their physical actuation on the fluid may be
mathematically modeled as the generation of surface velocities on a continuous
spherical surface -- a model known in the literature as squirming, which has
been used to address various aspects of the biological physics of locomotion.
Previous analyses of squirming assumed axisymmetric fluid motion and hence
restricted all swimming kinematics to take place along a line. In this paper we
generalize squirming to three spatial dimensions. We derive analytically the
flow field surrounding a spherical squirmer with arbitrary surface motion, and
use it to derive its three-dimensional translational and rotational swimming
kinematics. We then use our results to physically interpret the flow field
induced by the swimmer in terms of fundamental flow singularities up to terms
decaying spatially as $\sim 1/r^3$. Our results will enable to develop new
models in biological physics, in particular in the area of hydrodynamic
interactions and collective locomotion.


title:
On the Klein-Gordon equation near a De Sitter brane in an Anti-de Sitter
  bulk

abstract:
  In this paper we investigate the Klein-Gordon equation in the past causal
domain of a De Sitter brane imbedded in a Anti-de Sitter bulk. We solve the
global mixed hyperbolic problem. We prove that any finite energy solution can
be expressed as a Kaluza-Klein tower that is a superposition of free fields in
the Steady State Universe, of which we study the asymptotic behaviours. We show
that the leading term of a gravitational fluctuation is a massless graviton,
i.e. the De Sitter brane is linearly stable.


title:
Compressive Diffusion Strategies Over Distributed Networks for Reduced
  Communication Load

abstract:
  We study the compressive diffusion strategies over distributed networks based
on the diffusion implementation and adaptive extraction of the information from
the compressed diffusion data. We demonstrate that one can achieve a comparable
performance with the full information exchange configurations, even if the
diffused information is compressed into a scalar or a single bit. To this end,
we provide a complete performance analysis for the compressive diffusion
strategies. We analyze the transient, steady-state and tracking performance of
the configurations in which the diffused data is compressed into a scalar or a
single-bit. We propose a new adaptive combination method improving the
convergence performance of the compressive diffusion strategies further. In the
new method, we introduce one more freedom-of-dimension in the combination
matrix and adapt it by using the conventional mixture approach in order to
enhance the convergence performance for any possible combination rule used for
the full diffusion configuration. We demonstrate that our theoretical analysis
closely follow the ensemble averaged results in our simulations. We provide
numerical examples showing the improved convergence performance with the new
adaptive combination method.


title:
Correspondence between the NLS equation for optical fibers and a class
  of integrable NLS equations

abstract:
  The propagation of the optical field complex envelope in a single-mode fiber
is governed by a one-dimensional cubic nonlinear Schr\"odinger equation with a
loss term. We present a result about $L^2$-closeness of the solutions of the
above-mentioned equation and of a one-dimensional nonlinear Schr\"odinger
equation that is Painlev\'e integrable.


title:
Lagrangian ADER-WENO Finite Volume Schemes on Unstructured Tetrahedral
  Meshes for Conservative and Nonconservative Hyperbolic Systems in 3D

abstract:
  In this paper we present a new family of high order accurate
Arbitrary-Lagrangian-Eulerian (ALE) one-step ADER-WENO finite volume schemes
for the solution of nonlinear systems of conservative and non-conservative
hyperbolic partial differential equations with stiff source terms on moving
tetrahedral meshes in three space dimensions. A WENO reconstruction technique
is used to achieve high order of accuracy in space, while an element-local
space-time Discontinuous Galerkin finite element predictor on moving meshes is
used to obtain a high order accurate one-step time discretization. Within the
space-time predictor the physical element is mapped onto a reference element
using an isoparametric approach, where the space-time basis and test functions
are given by the Lagrange interpolation polynomials passing through a
predefined set of space-time nodes. Since our algorithm is cell-centered, the
final mesh motion is computed by using a suitable node solver algorithm. A
rezoning step as well as a flattener strategy are used in some of the test
problems to avoid mesh tangling or excessive element deformations that may
occur when the computation involves strong shocks or shear waves. We apply our
new high order unstructured ALE schemes to the 3D Euler equations of
compressible gas dynamics, for which a set of classical numerical test problems
has been solved and for which convergence rates up to sixth order of accuracy
in space and time have been obtained. We furthermore consider the equations of
classical ideal magnetohydrodynamics (MHD) as well as the non-conservative
seven-equation Baer-Nunziato model of compressible multi-phase flows with stiff
relaxation source terms.


title:
A New Class of Complex Ejecta Resulting from the Interaction of two CMEs
  and its Expected Geoeffectiveness

abstract:
  A significant portion of transients measured by spacecraft at 1 AU does not
show the well-defined properties of magnetic clouds (MCs). Here, we propose a
new class of complex, non-MC ejecta resulting from the interaction of two CMEs
with different orientation, which differ from the previously studied
multiple-MC event. At 1 AU, they are associated with a smooth rotation of the
magnetic field vector over an extended duration and do not show clear signs of
interaction. We determine the characteristics of such events based on a
numerical simulation and identify and analyze a potential case in the
long-duration CME measured in situ in 2001 March 19-22. Such events may result
in intense, long-duration geo-magnetic storms, with sawtooth events, and may
sometimes be misidentified as isolated CMEs.


title:
Symblicit algorithms for optimal strategy synthesis in monotonic Markov
  decision processes (extended version)

abstract:
  When treating Markov decision processes (MDPs) with large state spaces, using
explicit representations quickly becomes unfeasible. Lately, Wimmer et al. have
proposed a so-called symblicit algorithm for the synthesis of optimal
strategies in MDPs, in the quantitative setting of expected mean-payoff. This
algorithm, based on the strategy iteration algorithm of Howard and Veinott,
efficiently combines symbolic and explicit data structures, and uses binary
decision diagrams as symbolic representation. The aim of this paper is to show
that the new data structure of pseudo-antichains (an extension of antichains)
provides another interesting alternative, especially for the class of monotonic
MDPs. We design efficient pseudo-antichain based symblicit algorithms (with
open source implementations) for two quantitative settings: the expected
mean-payoff and the stochastic shortest path. For two practical applications
coming from automated planning and LTL synthesis, we report promising
experimental results w.r.t. both the run time and the memory consumption.


title: Minimal mechanisms for vegetation patterns in semiarid regions

abstract:
  The minimal ecological requirements for formation of regular vegetation
patterns in semiarid systems have been recently questioned. Against the general
belief that a combination of facilitative and competitive interactions is
necessary, recent theoretical studies suggest that, under broad conditions,
nonlocal competition among plants alone may induce patterns. In this paper, we
review results along this line, presenting a series of models that yield
spatial patterns when finite-range competition is the only driving force. A
preliminary derivation of this type of model from a more detailed one that
considers water-biomass dynamics is also presented. Keywords: Vegetation
patterns, nonlocal interactions


title:
Calibration and performance of the STAR Muon Telescope Detector using
  cosmic rays

abstract:
  We report the timing and spatial resolution from the Muon Telescope Detector
(MTD) installed in the STAR experiment at RHIC. Cosmic ray muons traversing the
STAR detector have an average transverse momentum of 6 GeV/c. Due to their very
small multiple scattering, these cosmic muons provide an ideal tool to
calibrate the detectors and measure their timing and spatial resolution. The
values obtained were ~100 ps and ~1-2 cm, respectively. These values are
comparable to those obtained from cosmic-ray bench tests and test beams.


title:
NuSTAR results and future plans for magnetar and rotation-powered pulsar
  observations

abstract:
  The Nuclear Spectroscopic Telescope Array (NuSTAR) is the first focusing hard
X-ray mission in orbit and operates in the 3-79 keV range. NuSTAR's sensitivity
is roughly two orders of magnitude better than previous missions in this energy
band thanks to its superb angular resolution. Since its launch in 2012 June,
NuSTAR has performed excellently and observed many interesting sources
including four magnetars, two rotation-powered pulsars and the cataclysmic
variable AE Aquarii. NuSTAR also discovered 3.76-s pulsations from the
transient source SGR J1745-29 recently found by Swift very close to the
Galactic Center, clearly identifying the source as a transient magnetar. For
magnetar 1E 1841-045, we show that the spectrum is well fit by an absorbed
blackbody plus broken power-law model with a hard power-law photon index of
~1.3. This is consistent with previous results by INTEGRAL and RXTE. We also
find an interesting double-peaked pulse profile in the 25-35 keV band. For AE
Aquarii, we show that the spectrum can be described by a multi-temperature
thermal model or a thermal plus non-thermal model; a multi-temperature thermal
model without a non-thermal component cannot be ruled out. Furthermore, we do
not see a spiky pulse profile in the hard X-ray band, as previously reported
based on Suzaku observations. For other magnetars and rotation-powered pulsars
observed with NuSTAR, data analysis results will be soon available.


title:
Regimes of nonlinear depletion and regularity in the 3D Navier-Stokes
  equations

abstract:
  The periodic $3D$ Navier-Stokes equations are analyzed in terms of
dimensionless, scaled, $L^{2m}$-norms of vorticity $D_{m}$ ($1 \leq m <
\infty$). The first in this hierarchy, $D_{1}$, is the global enstrophy. Three
regimes naturally occur in the $D_{1}-D_{m}$ plane. Solutions in the first
regime, which lie between two concave curves, are shown to be regular, owing to
strong nonlinear depletion. Moreover, numerical experiments have suggested, so
far, that all dynamics lie in this heavily depleted regime \cite{DGGKPV13}\,;
new numerical evidence for this is presented. Estimates for the dimension of a
global attractor and a corresponding inertial range are given for this regime.
However, two more regimes can theoretically exist. In the second, which lies
between the upper concave curve and a line, the depletion is insufficient to
regularize solutions, so no more than Leray's weak solutions exist. In the
third, which lies above this line, solutions are regular, but correspond to
extreme initial conditions. The paper ends with a discussion on the possibility
of transition between these regimes.


title: On the nonlocality of the state and wave equation of Treeby and Cox

abstract:
  In this paper it is shown that the state equation of Treeby and Cox [B. E.
Treeby and B. T. Cox, J. Acoust. Soc. Am. \textbf{127} 5, (2010)] is
\emph{nonlocal}, more precisely, a \emph{local} density variation causes an
\emph{instant global} pressure variation and a \emph{local} pressure variation
can only be caused by an \emph{instant global} density variation. This is in
contrast to all frequency dependent dissipative state equations known to the
author. Moreover, it is shown that the Green function $G$ of the wave equation
of Treeby and Cox cannot have a \emph{finite} wave front speed, i.e. there
exists no finite $c_F>0$ such that $$
  G(\mathbf{x},t) = 0 \qquad\mbox{for}\qquad |\mathbf{x}|/c_F > t $$ holds,
where $|\mathbf{x}|/c_F$ corresponds to the \emph{travel time} of a wave
propagating with speed $c_F$ from point $\mathbf{0}$ to point $\mathbf{x}$. As
a consequence, the density and pressure waves satisfying (i) the state equation
of Treeby and Cox, (ii) the equation of motion and (iii) the equation of
continuity do not have a \emph{finite} wave front speed.


title: Pseudospectra in non-Hermitian quantum mechanics

abstract:
  We propose giving the mathematical concept of the pseudospectrum a central
role in quantum mechanics with non-Hermitian operators. We relate
pseudospectral properties to quasi-Hermiticity, similarity to self-adjoint
operators, and basis properties of eigenfunctions. The abstract results are
illustrated by unexpected wild properties of operators familiar from
PT-symmetric quantum mechanics.


title:
Lithium atom storage in nanoporous cellulose via surface induced $\rm
  Li_2$ breakage

abstract:
  We demonstrate a physical mechanism that enhances a splitting of diatomic
$\rm Li_2$ at cellulose surfaces. The origin of this splitting is a possible
surface induced diatomic excited state resonance repulsion. The atomic Li is
then free to form either physical or chemical bonds with the cellulose surface
and even diffuse into the cellulose layer structure. This allows for an
enhanced storage capacity of atomic Li in nanoporous cellulose


title: Scaling limits of k-ary growing trees

abstract:
  For each integer $k \geq 2$, we introduce a sequence of $k$-ary discrete
trees constructed recursively by choosing at each step an edge uniformly among
the present edges and grafting on "its middle" $k-1$ new edges. When $k=2$,
this corresponds to a well-known algorithm which was first introduced by
R\'emy. Our main result concerns the asymptotic behavior of these trees as $n$
becomes large: for all $k$, the sequence of $k$-ary trees grows at speed
$n^{1/k}$ towards a $k$-ary random real tree that belongs to the family of
self-similar fragmentation trees. This convergence is proved with respect to
the Gromov-Hausdorff-Prokhorov topology. We also study embeddings of the
limiting trees when $k$ varies.


title: Galactic planetary science

abstract:
  Planetary science beyond the boundaries of our Solar System is today in its
infancy. Until a couple of decades ago, the detailed investigation of the
planetary properties was restricted to objects orbiting inside the Kuiper Belt.
Today, we cannot ignore that the number of known planets has increased by two
orders of magnitude nor that these planets resemble anything but the objects
present in our own Solar System. Whether this fact is the result of a selection
bias induced by the kind of techniques used to discover new planets -mainly
radial velocity and transit - or simply the proof that the Solar System is a
rarity in the Milky Way, we do not know yet. What is clear, though, is that the
Solar System has failed to be the paradigm not only in our Galaxy but even
'just' in the solar neighbourhood. This finding, although unsettling, forces us
to reconsider our knowledge of planets under a different light and perhaps
question a few of the theoretical pillars on which we base our current
'understanding'. The next decade will be critical to advance in what we should
perhaps call Galactic planetary science. In this paper, we review highlights
and pitfalls of our current knowledge of this topic and elaborate on how this
knowledge might arguably evolve in the next decade.More critically, we identify
what should be the mandatory scientific and technical steps to be taken in this
fascinating journey of remote exploration of planets in our Galaxy.


title: Scott rank of Polish metric spaces

abstract:
  Following the work of Friedman, Koerwien, Nies and Schlicht we positively
answer their question whether the Scott rank of Polish metric spaces is
countable.


title: The quantum vacuum

abstract:
  The vacuum is the lowest energy state of a field in a certain region of
space. This definition implies that no particles can be present in the vacuum
state. In classical physics, the only features of vacuum are those of its
geometry. For example, in the general theory of relativity the geometry is a
dynamical structure that guides the motion of matter, and, in turn, it is bent
and curved by the presence of matter. Other than this, the classical vacuum is
a structure void of any physical properties, since classically properties are
strictly associated with physical objects such as particles and
finite-amplitude fields. The situation is very different in quantum physics. As
I will show in this paper, the difference stems from the fact that in quantum
physics the properties are not strictly tied to objects. We know for example
that physical properties come into existence - as values of observables - only
when the object is measured. Thus, quantum physics allows us to detach
properties from objects. This has consequences: one does not need pre-existing
real objects to create actual properties, and indeed under certain
perturbations the quantum vacuum produces observable effects such as energy
shifts and creation of particles. An open question is if by necessity the
vacuum comes with an embedded geometry, and if it is possible to construct
viable physical theories in which geometry is detached from the vacuum.


title:
Efficient MIMO Transmission of PSK Signals With a Single-Radio
  Reconfigurable Antenna

abstract:
  Crucial developments to the recently introduced signal-space approach for
multiplexing multiple data symbols using a single-radio switched antenna are
presented. First, we introduce a general framework for expressing the spatial
multiplexing relation of the transmit signals only from the antenna scattering
parameters and the modulating reactive loading. This not only avoids tedious
far-field calculations, but more importantly provides an efficient and
practical strategy for spatially multiplexing PSK signals of any modulation
order. The proposed approach allows ensuring a constant impedance matching at
the input of the driving antenna for all symbol combinations, and as
importantly uses only passive reconfigurable loads. This obviates the use of
reconfigurable matching networks and active loads, respectively, thereby
overcoming stringent limitations of previous single-feed MIMO techniques in
terms of complexity, efficiency, and power consumption. The proposed approach
is illustrated by the design of a realistic very compact antenna system
optimized for multiplexing QPSK signals. The results show that the proposed
approach can bring the MIMO benefits to the low-end user terminals at a reduced
RF complexity.


title:
Null hypothesis significance tests: A mix-up of two different theories,
  the basis for widespread confusion and numerous misinterpretations

abstract:
  Null hypothesis statistical significance tests (NHST) are widely used in
quantitative research in the empirical sciences including scientometrics.
Nevertheless, since their introduction nearly a century ago significance tests
have been controversial. Many researchers are not aware of the numerous
criticisms raised against NHST. As practiced, NHST has been characterized as a
null ritual that is overused and too often misapplied and misinterpreted. NHST
is in fact a patchwork of two fundamentally different classical statistical
testing models, often blended with some wishful quasi-Bayesian interpretations.
This is undoubtedly a major reason why NHST is very often misunderstood. But
NHST also has intrinsic logical problems and the epistemic range of the
information provided by such tests is much more limited than most researchers
recognize. In this article we introduce to the scientometric community the
theoretical origins of NHST, which is mostly absent from standard statistical
textbooks, and we discuss some of the most prevalent problems relating to the
practice of NHST and trace these problems back to the mixup of the two
different theoretical origins. Finally, we illustrate some of the
misunderstandings with examples from the scientometric literature and bring
forward some modest recommendations for a more sound practice in quantitative
data analysis.


title:
Signatures of Rashba Spin-Orbit Interaction in Charge and Spin
  Properties of Quantum Hall Systems

abstract:
  We study the local equilibrium properties of two-dimensional electron gases
at high magnetic fields in the presence of random smooth electrostatic
disorder, Rashba spin-orbit coupling, and the Zeeman interaction. Using a
systematic magnetic length ($l_B$) expansion within a Green's function
framework we derive quantum functionals for the local spin-resolved particle
and current densities which can be useful for future studies combining disorder
and mean-field electron-electron interaction in the quantum Hall regime. We
point out that the spin polarization presents a peculiar spatial dependence
which can be used to determine the strength of the Rashba coupling by local
probes. The spatial structure of the current density, consisting of both
compressible and incompressible contributions, also essentially reflects the
effects of Rashba spin-orbit interaction on the energy spectrum. We show that
in the semiclassical limit $l_B \rightarrow 0$ the local Hall conductivity
remains, however, still quantized in units of $e^2/h$ for any finite strength
of the spin-orbit interaction. In contrast, it becomes half-integer quantized
when the latter is infinite, a situation which corresponds to a disordered
topological insulator surface consisting of a single Dirac cone. Finally, we
argue how to define at high magnetic fields a spin Hall conductivity related to
a dissipationless angular momentum flow, which is characterized by a sequence
of plateaus as a function of the inverse magnetic field (thus free of
resonances).


title:
Microscopic magnetic modeling for the $S$=1/2 alternating chain
  compounds Na$_3$Cu$_2$SbO$_6$ and Na$_2$Cu$_2$TeO$_6$

abstract:
  The spin-1/2 alternating Heisenberg chain system Na$_3$Cu$_2$SbO$_6$ features
two relevant exchange couplings: $J_{1a}$ within the structural Cu$_2$O$_6$
dimers and $J_{1b}$ between the dimers. Motivated by the controversially
discussed nature of $J_{1a}$, we perform extensive density-functional-theory
(DFT) calculations, including DFT+$U$ and hybrid functionals. Fits to the
experimental magnetic susceptibility using high-temperature series expansions
and quantum Monte Carlo simulations yield the optimal parameters $J_{1a}$ =
$-$217 K and $J_{1b}$ = 174 K with the alternation ratio $\alpha =
J_{1a}/J_{1b} \simeq$ $-$1.25. For the closely related system
Na$_2$Cu$_2$TeO$_6$, DFT yields substantially enhanced $J_{1b}$, but weaker
$J_{1a}$. The comparative analysis renders the buckling of the chains as the
key parameter altering the magnetic coupling regime. Numerical simulation of
the dispersion relations of the alternating chain model clarify why both
antiferromagnetic and ferrromagnetic $J_{1a}$ can reproduce the experimental
magnetic susceptibility data.


title: Signal and System Approximation from General Measurements

abstract:
  In this paper we analyze the behavior of system approximation processes for
stable linear time-invariant (LTI) systems and signals in the Paley-Wiener
space PW_\pi^1. We consider approximation processes, where the input signal is
not directly used to generate the system output, but instead a sequence of
numbers is used that is generated from the input signal by measurement
functionals. We consider classical sampling which corresponds to a pointwise
evaluation of the signal, as well as several more general measurement
functionals. We show that a stable system approximation is not possible for
pointwise sampling, because there exist signals and systems such that the
approximation process diverges. This remains true even with oversampling.
However, if more general measurement functionals are considered, a stable
approximation is possible if oversampling is used. Further, we show that
without oversampling we have divergence for a large class of practically
relevant measurement procedures.


title: Quantum Systems Equilibrate Rapidly for Most Observables

abstract:
  Considering any Hamiltonian, any initial state, and measurements with a small
number of possible outcomes compared to the dimension, we show that most
measurements are already equilibrated. To investigate non-trivial equilibration
we therefore consider a restricted set of measurements. When the initial state
is spread over many energy levels, and we consider the set of observables for
which this state is an eigenstate, most observables are initially out of
equilibrium yet equilibrate rapidly. Moreover, all two-outcome measurements,
where one of the projectors is of low rank, equilibrate rapidly.


title: Quantisation Spaces of Cluster Algebras

abstract:
  The article concerns the existence and uniqueness of quantisations of cluster
algebras. We prove that cluster algebras with an initial exchange matrix of
full rank admit a quantisation in the sense of Berenstein-Zelevinsky and give
an explicit generating set to construct all quantisations.


title:
Using Topological Insulator Proximity to Generate Perfectly Conducting
  Channels in Materials without Topological Protection

abstract:
  We show that hybrid structures of topological insulators and materials
without topological protection can be employed to create perfectly conducting
channels hosted in the non-topological part. These states inherit the
topological protection from the proximity of the topological insulator but are
more fragile to time-reversal symmetry breaking because of their extended
character. We explore their formation in the band structure of model hybrid
systems as well as realistic heterostructures involving HgTe/CdTe-based
two-dimensional topological insulators. Using numerical quantum transport
calculations for the HgTe/CdTe material system we propose two experimental
settings which allow for the detection of the induced perfectly conducting
channels, both in the localized and diffusive regime, by means of magneto
conductance and shot noise.


title:
Levy-Khintchine random matrices and the Poisson weighted infinite
  skeleton tree

abstract:
  We study a class of Hermitian random matrices which includes and generalizes
Wigner matrices, heavy-tailed random matrices, and sparse random matrices such
as the adjacency matrices of Erdos-Renyi random graphs with p ~ 1/N. Our NxN
random matrices have real entries which are i.i.d. up to symmetry. The
distributions may depend on N, however, the sums of rows must converge in
distribution; it is then well-known that the limiting distributions are
infinitely divisible.
  We show that a limiting empirical spectral distribution (LSD) exists, and via
local weak convergence of associated graphs, the LSD corresponds to the
spectral measure at the root of a Poisson weighted infinite skeleton tree. This
graph is formed by connecting infinitely many Poisson weighted infinite trees
using a backbone structure. One example covered by the results are matrices
with i.i.d. entries having infinite second moments, but normalized to be in the
Gaussian domain of attraction. In this case, the limiting graph is just the
positive integer line rooted at 1, and as expected, the LSD is Wigner's
semi-circle law. The results also extend to self-adjoint complex matrices and
also to Wishart matrices.


title:
On weakly locally uniformly rotund norms which are not locally uniformly
  rotund

abstract:
  We show that every infinite-dimensional Banach space with separable dual
admits an equivalent norm which is weakly locally uniformly rotund but not
locally uniformly rotund.


title: $C^{\infty}$ regularity of certain thin free boundaries

abstract:
  We continue our study of the free boundary regularity in the thin one-phase
problem and show that $C^{2,\alpha}$ free boundaries are smooth.


title:
Levels of Abstraction and the Apparent Contradictory Philosophical
  Legacy of Turing and Shannon

abstract:
  In a recent article, Luciano Floridi explains his view of Turing's legacy in
connection to the philosophy of information. I will very briefly survey one of
Turing's other contributions to the philosophy of information and computation,
including similarities to Shannon's own methodological approach to information
through communication, showing how crucial they are and have been as
methodological strategies to understanding key aspects of these concepts. While
Floridi's concept of Levels of Abstraction is related to the novel methodology
of Turing's imitation game for tackling the question of machine intelligence,
Turing's other main contribution to the philosophy of information runs contrary
to it. Indeed, the seminal concept of computation universality strongly
suggests the deletion of fundamental differences among seemingly different
levels of description. How might we reconcile these apparently contradictory
contributions? I will argue that Turing's contribution should prompt us to plot
some directions for a philosophy of information and computation, one that
closely parallels the most important developments in computer science, one that
understands the profound implications of the works of Turing, Shannon and
others.


title: A Dedekind-Mertens theorem for power series rings

abstract:
  We prove a power series ring analogue of the Dedekind-Mertens lemma. Along
the way, we give limiting counterexamples, we note an application to
integrality, and we correct an error in the literature.


title: The group of unimodular automorphisms of $\mathbb{C}^2$ is hopfian

abstract:
  Let $G$ be the group of unimodular automorphisms of $\mathbb C^2$. In the
paper we prove two interesting results about this group. The first one is about
absence of non-trivial finite-dimensional representations of $G$. The second
one, we show that any non-trivial group endomorphism of $G$ is a monomorphism,
which implies that $G$ is hopfian.


title:
Generic hyperelliptic Prym varieties in a generalized Henon-Heiles
  system

abstract:
  It is known that the Jacobian of an algebraic curve which is a 2-fold
covering of a hyperelliptic curve ramified at two points contains a
hyperelliptic Prym variety. Its explicit algebraic description is applied to
some of the integrable Henon-Heiles systems with a non-polynomial potential.
Namely, we identify the generic complex invariant manifolds of the systems as a
hyperelliptic Prym subvariety of the Jacobian of the spectral curve of the
corresponding Lax representation.
  The exact discretization of the system is described as a translation on the
Prym variety.


title: Pressure-driven fragmentation of clouds at high redshift

abstract:
  The discovery of a hyper metal-poor star with total metallicity of $\le
10^{-5}$ Z$_\odot$, has motivated new investigations of how such objects can
form from primordial gas polluted by a single supernova. In this paper we
present a shock-cloud model which simulates a supernova remnant interacting
with a cloud in a metal-free environment at redshift $z=10$. Pre-supernova
conditions are considered, which include a multiphase neutral medium and H II
region. A small dense clump ($n=100$ cm$^{-3}$), located 40 pc from a 40
M$_\odot$ metal-free star, embedded in a $n=10$ cm$^{-3}$ ambient cloud. The
evolution of the supernova remnant (explosion energy $10^{52}$ erg) and its
subsequent interaction with the dense clump is examined. This is the first
study to include a comprehensive treatment of the non-equilibrium chemistry and
associated radiative cooling that is occurring at all stages of the shock-cloud
model. We have included a primordial chemistry network that covers the
temperature range $10-10^9$ K, and is coupled to thermal models of atomic &
molecular cooling. We find $\times10^{3}$ density enhancement of the clump (i.e
maximum density $\sim 78000$ cm$^{-3}$) within this metal-free model. This is
consistent with Galactic shock-cloud models considering solar metallicity gas
with equilibrium cooling functions. Despite this strong compression, the cloud
does not become gravitationally unstable. We find that the small cloud modelled
here is destroyed for shock velocities $\gtrsim 50\,$km s$^{-1}$, and not
significantly affected by shocks with velocity $\lesssim 30\,$km s$^{-1}$.
Rather specific conditions are required to make such a cloud collapse.


title: Unitary Holonomies by Direct Degenerate Projections

abstract:
  An incomplete quantum measurement can induce non-trivial dynamics between
degenerate subspaces, a closed sequence of such projections produces a
non-abelian holonomy. We show how to induce unitary evolution on an initial
subspace from such finite discrete sequences and also construct a near
deterministic repeat-until-success protocol. We also prove necessary and
sufficient criteria on the auxiliary Hilbert space dimension required for
inducing isometries between between subspaces.


title:
Universality and time-scale invariance for the shape of planar L\'evy
  processes

abstract:
  For a broad class of planar Markov processes, viz. L\'evy processes
satisfying certain conditions (valid \textit{eg} in the case of Brownian motion
and L\'evy flights), we establish an exact, universal formula describing the
shape of the convex hull of sample paths. We show indeed that the average
number of edges joining paths' points separated by a time-lapse $\Delta \tau
\in \left[\Delta \tau _1, \Delta \tau_2\right]$ is equal to $2\ln \left(\Delta
\tau_2 / \Delta \tau_1 \right)$, regardless of the specific distribution of the
process's increments and regardless of its total duration $T$. The formula also
exhibits invariance when the time scale is multiplied by any constant.
  Apart from its theoretical importance, our result provides new insights
regarding the shape of two-dimensional objects modelled by stochastic
processes' sample paths (\textit{eg} polymer chains): in particular for a total
time (or parameter) duration $T$, the average number of edges on the convex
hull ("cut off" to discard edges joining points separated by a time-lapse
shorter than some $\Delta \tau < T$) will be given by $2 \ln
\left(\frac{T}{\Delta \tau}\right)$. Thus it will only grow logarithmically,
rather than at some higher pace.


title:
Reduced-order Abraham-Lorentz-Dirac equation and the consistency of
  classical electromagnetism

abstract:
  It is widely believed that classical electromagnetism is either unphysical or
inconsistent, owing to pathological behavior when self-force and radiation
reaction are non-negligible. We argue that there is no inconsistency as long as
it is recognized that certain types of charge distribution are simply
impossible, such as, for example, a point particle with finite charge and
finite inertia. This is owing to the fact that negative inertial mass is an
unphysical concept in classical physics. It remains useful to obtain an
equation of motion for small charged objects that describes their motion to
good approximation without requiring knowledge of the charge distribution
within the object. We give a simple method to achieve this, leading to a
reduced-order form of the Abraham-Lorentz-Dirac equation, essentially as
proposed by Eliezer, Landau and Lifshitz, and derived by Ford and O'Connell.


title: Approximation Algorithms for Covering and Packing Problems on Paths

abstract:
  Routing and scheduling problems are fundamental problems in combinatorial
optimization, and also have many applications. Most variations of these
problems are NP-Hard, so we need to use heuristics to solve these problems on
large instances, which are fast and yet come close to the optimal value. In
this thesis, we study the design and analysis of approximation algorithms for
such problems. We focus on two important class of problems. The first is the
Unsplittable Flow Problem and some of its variants and the second is the
Resource Allocation for Job Scheduling Problem and some of its variants. The
first is a packing problem, whereas the second is a covering problem.


title:
Extrinsic projective curves X^1 in P^2(C): harmony with intrinsic
  cohomology

abstract:
  On a geometrically smooth complex algebraic curve X^1 in P^2(C), represented
in complex affine coordinates (x,y) as the zero-locus R(x,y) = 0 of some
polynomial R of degree d >= k+3, an explicit family of generating independent
holomorphic jet differentials J_R^1, ..., J_R^k expressed in terms of R and its
partial derivatives is exhibited with its new precious nonlinearity features as
a complete explicitation of all holomorphic sections of the Green-Griffiths
bundle of m-homogeneous polynomialized order k jets of local holomorphic maps
from a complex disc into X^1.


title:
The Detailed Photometric and Spectroscopic Study of the 2011 Outburst of
  the Recurrent Nova T Pyxidis from 0.8 to 250 Days after Discovery

abstract:
  We investigated the optical lightcurve of T Pyx during its 2011 outburst by
compiling a database of SMEI and AAVSO observations. The SMEI lightcurve,
providing unprecedented detail covering 1.5-49d post-discovery, was divided
into four phases based on the idealised CN optical lightcurve; the initial rise
(1.5-3.3d), the pre-maximum halt (3.3-13.3d), the final rise (14.7-27.9d), and
the early decline (27.9d-). The SMEI lightcurve contains a strongly detected
period of 1.44+/-0.05d during the pre-maximum phase. These oscillations
resemble those found in TNR models arising from instabilities in the expanding
envelope. No spectral variation mirroring the lightcurve periodicity was found.
A marked dip at 22-24d just before maximum light (27.9d) may represent the same
phenomenon seen in novae observed by SMEI. Spectra from the Liverpool Telescope
and SMARTS 1.5m were obtained from 0.8-80.7 and 155.1-249.9d, covering the
major phases of development. A distinct high velocity ejection phase was
evident during the early rise (V~4000 km/s). A marked drop at 5.7d, and then a
gradual increase occurred in the ejection velocity which stabilised at ~1500
km/s at the pre-maximum halt. Here we propose two stages of mass loss, a
short-lived phase occurring immediately after outburst, lasting ~6d, followed
by a steadily evolving and higher mass loss phase. The overall spectral
development follows that typical of a CN and comparison with the photometric
behaviour reveals consistencies with the evolving pseudo-photosphere model of a
CN outburst. Comparing optical spectra to X-ray and radio lightcurves, weak [Fe
X] 6375 Angstrom emission was marginally detected before the X-ray rise and was
clearly present during the brightest phase of X-ray emission. If the onset of
the X-ray phase and the start of the optical final decline are related to the
cessation of significant mass loss, then this occurred at 90-110d.


title: GRBs from Weakly-Magnetized, Slowly-Rotating Stars in Binaries

abstract:
  The spin of a number of black holes (BHs) in X-ray binaries (XBs) has been
predicted (and, in at least three cases, confirmed by observations) by using a
binary stellar evolution model with Case-C mass transfer . The rotational
energy of such BHs is sufficient to power up (long) gamma-ray bursts and
hypernovae (GRBs/HNe) and still leave a Kerr BH behind. However, strong
magnetic fields (B fields) and/or dynamo effects in the interior of a
BH-progenitor star may be capable of rapidly depleting the angular momentum
from the stellar core, hence, preventing the formation of a collapsar. Thus,
even if binaries can produce Kerr BHs, most of their rotation is acquired from
accreting the stellar mantle, with a long delay between the formation of the BH
and its spin up. Hence, not being good sources of GRBs.
  We study the necessary conditions to produce GRBs by the progenitors of such
BHs. Tidal-synchronization and Alfv\'en timescales are compared for B fields of
different intensities threading trough He stars. We search for a B-field range
which allows tidal spin up all the way into stellar core but prevents its slow
down during differential rotation phases. Energetics for producing a strong B
field during core collapse, which allows for GRB central engines, are also
estimated. An observationally-reasonable choice of parameters is found.


title: On the Riemann-Hilbert problem for the Beltrami equation

abstract:
  It is developed the theory of the Dirichlet problem for harmonic functions.
On this basis, for the nondegenerate Beltrami equations in the quasidisks and,
in particular, in the smooth domains, it is proved the existence of regular
solutions of the Riemann-Hilbert problem with coefficients of bounded variation
and boundary data that are measurable with respect to the absolute harmonic
measure (logarithmic capacity). Moreover, it is shown that the dimension of the
spaces of the given solutions is infinite.
  One more section was added for the case of coefficients of countably bounded
variation.


title: An algebra whose subalgebras are characterized by density

abstract:
  We refine a construction of Choi, Farah and Ozawa to build a nonseparable
amenable operator algebra $\mathcal A\subseteq\ell_\infty(M_2)$ whose
nonseparable subalgebras, including $\mathcal A$, are not isomorphic to a
$C^*$-algebra. This is done using a Luzin gap and a uniformly bounded group
representation.
  Next, we study additional properties of $\mathcal A$ and of its separable
subalgebras, related to the Kadison Kastler metric.


title: Theoretical probing of inelastic spin-excitations in adatoms on surfaces

abstract:
  We review our recent work on the simulation, description and prediction of
spin-excitations in adatoms and dimers deposited on metallic surfaces. This
work done together with Douglas L. Mills, is an extension of his seminal
contribution (with Pascal Lederer) published 50 years ago on the spin-dynamics
of transition metal impurities embedded in transition metal hosts [P. Lederer,
D.L. Mills, Phys. Rev. {\bf 160}, 590 (1967)]. The main predictions of his
model were verified experimentally with state of the art inelastic scanning
tunneling spectroscopy on adatoms. Our formalism, presented in this review, is
based on time-dependent density functional theory, combined with the
Korringa-Kohn-Rostoker Green function method. Comparison to experiments is
shown and discussed in detail. Our scheme enables the description and
prediction of the main characteristics of these excitations, \emph{i.e.} their
resonance frequency, their lifetime and their behavior upon application of
external perturbations such as a magnetic field.


title:
Radial Quasiballistic Transport in Time-Domain Thermoreflectance Studied
  Using Monte Carlo Simulations

abstract:
  Recently, a pump beam size dependence of thermal conductivity was observed in
Si at cryogenic temperatures using time-domain thermal reflectance (TDTR).
These observations were attributed to quasiballistic phonon transport, but the
interpretation of the measurements has been semi-empirical. Here we present a
numerical study of the heat conduction that occurs in the full 3D geometry of a
TDTR experiment, including an interface, using the Boltzmann Transport
Equation. We identify the radial suppression function that describes the
suppression in heat flux, compared to Fourier's law, that occurs due to
quasiballistic transport and demonstrate good agreement with experimental data.
We also discuss unresolved discrepancies that are important topics for future
study.


title:
Thermal-inertial effects on magnetic reconnection in relativistic pair
  plasmas

abstract:
  The magnetic reconnection process is studied in relativistic pair plasmas
when the thermal and inertial properties of the magnetohydrodynamical fluid are
included. We find that in both Sweet-Parker and Petschek relativistic scenarios
there is an increase of the reconnection rate owing to the thermal-inertial
effects, both satisfying causality. To characterize the new effects we define a
thermal-inertial number which is independent of the relativistic Lundquist
number, implying that reconnection can be achieved even for vanishing
resistivity as a result of only thermal-inertial effects. The current model has
fundamental importance for relativistic collisionless reconnection, as it
constitutes the simplest way to get reconnection rates faster than those
accessible with the sole resistivity.

categories: physics.plasm-ph astro-ph.HE astro-ph.SR physics.space-ph


title: Kummer congruences arising from the mirror symmetry of an elliptic curve

abstract:
  In the genus 1 case, mirror symmetry reduces to the statement that a certain
family of generating functions, relating to an elliptic curve, are
quasimodular. In their proof of this fact, Kaneko and Zagier used a related
family of generating functions $A_n(\tau)$, which they show to be quasimodular.
We show that these $A_n$'s also satisfy Kummer-type congruences. Additionally,
we show that for a prime $p$, the $p$th power coefficients of $A_n$
$p$-adically converge to zero, for specific values of $n$.


title:
A Direct Reconstruction Method for Anisotropic Electrical Impedance
  Tomography

abstract:
  A novel computational, non-iterative and noise-robust reconstruction method
is introduced for the planar anisotropic inverse conductivity problem. The
method is based on bypassing the unstable step of the reconstruction of the
values of the isothermal coordinates on the boundary of the domain.
Non-uniqueness of the inverse problem is dealt with by recovering the unique
isotropic conductivity that can be achieved as a deformation of the measured
anisotropic conductivity by \emph{isothermal coordinates}. The method shows how
isotropic D-bar reconstruction methods have produced reasonable and informative
reconstructions even when used on EIT data known to come from anisotropic
media, and when the boundary shape is not known precisely. Furthermore, the
results pave the way for regularized anisotropic EIT. Key aspects of the
approach involve D-bar methods and inverse scattering theory, complex
geometrical optics solutions, and quasi-conformal mapping techniques.


title: Universality of Block Copolymer Melts

abstract:
  Simulations of five different coarse-grained models of symmetric diblock
copolymer melts are compared to demonstrate a universal (i.e.,
model-independent) dependence of the free energy on the invariant degree of
polymerization $\overline{N}$, and to study universal properties of the
order-disorder transition (ODT). The ODT appears to exhibit two regimes:
Systems of very long chains ($\overline{N} \gtrsim 10^{4}$) are well described
by the Fredrickson-Helfand theory, which assumes weak segregation near the ODT.
Systems of smaller but experimentally relevant values, $\overline{N} \lesssim
10^4$, undergo a transition between strongly segregated disordered and lamellar
phases that, though universal, is not adequately described by any existing
theory.


title: Positroid Stratification of Orthogonal Grassmannian and ABJM Amplitudes

abstract:
  A novel understanding of scattering amplitudes in terms of on-shell diagrams
and positive Grassmannian has been recently established for four dimensional
Yang-Mills theories and three dimensional Chern-Simons theories of ABJM type.
We give a detailed construction of the positroid stratification of orthogonal
Grassmannian relevant for ABJM amplitudes. On-shell diagrams are classified by
pairing of external particles. We introduce a combinatorial aid called `OG
tableaux' and map each equivalence class of on-shell diagrams to a unique
tableau. The on-shell diagrams related to each other through BCFW bridging are
naturally grouped by the OG tableaux. Introducing suitably ordered BCFW bridges
and positive coordinates, we construct the complete coordinate charts to cover
the entire positive orthogonal Grassmannian for arbitrary number of external
particles. The graded counting of OG tableaux suggests that the positive
orthogonal Grassmannian constitutes a combinatorial polytope.


title:
Performance analysis of electronic structure codes on HPC systems: A
  case study of SIESTA

abstract:
  We report on scaling and timing tests of the SIESTA electronic structure code
for ab initio molecular dynamics simulations using density-functional theory.
The tests are performed on six large-scale supercomputers belonging to the
PRACE Tier-0 network with four different architectures: Cray XE6, IBM
BlueGene/Q, BullX, and IBM iDataPlex. We employ a systematic strategy for
simultaneously testing weak and strong scaling, and propose a measure which is
independent of the range of number of cores on which the tests are performed to
quantify strong scaling efficiency as a function of simulation size. We find an
increase in efficiency with simulation size for all machines, with a
qualitatively different curve depending on the supercomputer topology, and
discuss the connection of this functional form with weak scaling behaviour. We
also analyze the absolute timings obtained in our tests, showing the range of
system sizes and cores favourable for different machines. Our results can be
employed as a guide both for running SIESTA on parallel architectures, and for
executing similar scaling tests of other electronic structure codes.


title: The approach to gravity as a theory of embedded surface

abstract:
  We study the approach to gravity in which our curved spacetime is considered
as a surface in a flat ambient space of higher dimension (the embedding
theory). The dynamical variable in this theory is not a metric but an embedding
function. The Euler-Lagrange equations for this theory (Regge-Teitelboim
equations) are more general than the Einstein equations, and admit "extra
solutions" which do not correspond to any Einsteinian metric. The
Regge-Teitelboim equations can be explicitly analyzed for the solutions with
high symmetry. We show that symmetric embeddings of a static spherically
symmetric asymptotically flat metrics in a 6-dimensional ambient space do not
admit extra solutions of the vacuum Regge-Teitelboim equations. Therefore in
the embedding theory the solutions with such properties correspond to the
exterior Schwarzchild metric.


title:
Counting in hyperbolic spikes: the diophantine analysis of
  multihomogeneous diagonal equations

abstract:
  A method is described to sum multi-dimensional arithmetic functions subject
to hyperbolic summation conditions, provided that asymptotic formulae in
rectangular boxes are available. In combination with the circle method, the new
method is a versatile tool to count rational points on algebraic varieties
defined by multi-homogeneous diagonal equations.


title:
A first estimate of the NNLO nonresonant corrections to top-antitop
  threshold production at lepton colliders

abstract:
  We compute the dominant term in the expansion in rho=1-M_W/m_t of the unknown
next-to-next-to-leading order (NNLO) nonresonant contributions to the e+ e- ->
W+ W- b bbar total cross section at energies close to the top-antitop
threshold. Our analytic result disagrees with a previous calculation by other
authors [1]. We show that our determination has the correct infrared structure
needed to cancel the divergences proportional to the top width arising in the
resonant production of the same final state, and we point out to a missing
contribution in the computation of [1] to explain the discrepancy.


title: Spin Transfer Torque Generated by the Topological Insulator Bi_2Se_3

abstract:
  Magnetic devices are a leading contender for implementing memory and logic
technologies that are nonvolatile, that can scale to high density and high
speed, and that do not suffer wear-out. However, widespread applications of
magnetic memory and logic devices will require the development of efficient
mechanisms for reorienting their magnetization using the least possible current
and power. There has been considerable recent progress in this effort, in
particular discoveries that spin-orbit interactions in heavy metal/ferromagnet
bilayers can yield strong current-driven torques on the magnetic layer, via the
spin Hall effect in the heavy metal or the Rashba-Edelstein effect in the
ferromagnet. As part of the search for materials to provide even more efficient
spin-orbit-induced torques, some proposals have suggested topological
insulators (TIs), which possess a surface state in which the effects of
spin-orbit coupling are maximal in the sense that an electron's spin
orientation is locked relative to its propagation direction. Here we report
experiments showing that charge current flowing in-plane in a thin film of the
TI Bi_2Se_3 at room temperature can indeed apply a strong spin-transfer torque
to an adjacent ferromagnetic permalloy (Py = Ni81Fe19) thin film, with a
direction consistent with that expected from the topological surface state. We
find that the strength of the torque per unit charge current density in the
Bi_2Se_3 is greater than for any other spin-torque source material measured to
date, even for non-ideal TI films wherein the surface states coexist with bulk
conduction. Our data suggest that TIs have potential to enable very efficient
electrical manipulation of magnetic materials at room temperature for memory
and logic applications.


title: OSGA: A fast subgradient algorithm with optimal complexity

abstract:
  This paper presents an algorithm for approximately minimizing a convex
function in simple, not necessarily bounded convex domains, assuming only that
function values and subgradients are available. No global information about the
objective function is needed apart from a strong convexity parameter (which can
be put to zero if only convexity is known).
  The worst case number of iterations needed to achieve a given accuracy is
independent of the dimension (which may be infinite) and - apart from a
constant factor - best possible under a variety of smoothness assumptions on
the objective function.


title: Energy levels, radiative rates, and lifetimes for transitions in W XL

abstract:
  Energy levels and radiative rates are reported for transitions in Br-like W
XL, calculated with the general-purpose relativistic atomic structure package
({\sc grasp}). Configuration interaction (CI) has been included among 46
configurations (generating 4215 levels) over a wide energy range up to 213 Ryd.
However, for conciseness results are only listed for the lowest 360 levels
(with energies up to $\sim$ 43 Ryd), which mainly belong to the 4s$^2$4p$^5$,
4s$^2$4p$^4$4d, 4s$^2$4p$^4$4f, 4s4p$^6$, 4p$^6$4d, 4s4p$^5$4d,
4s$^2$4p$^3$4d$^2$, and 4s$^2$4p$^3$4d4f configurations, and provided for four
types of transitions, i.e. E1, E2, M1, and M2. Comparisons are made with
existing (but limited) results. However, to fully assess the accuracy of our
data, analogous calculations have been performed with the flexible atomic code
({\sc fac}), including even a larger CI than in {\sc grasp}. Our energy levels
are estimated to be accurate to better than 0.02 Ryd, whereas results for
radiative rates (and lifetimes) should be accurate to better than $20\%$ for a
majority of the strong transitions.


title:
A two-scale model for sheared fault gouge: Competition between
  macroscopic disorder and local viscoplasticity

abstract:
  We develop a model for sheared gouge layers that accounts for the local
increase in temperature at the grain contacts during sliding. We use the shear
transformation zone (STZ) theory, a statistical thermodynamic theory, to
describe irreversible macroscopic plastic deformations due to local
rearrangements of the gouge particles. We track the temperature evolution at
the grain contacts using a one dimensional heat diffusion equation. At low
temperatures, the strength of the asperities is limited by the flow strength,
as predicted by dislocation creep models. At high temperatures, some of the
constituents of the grains may melt leading to the degradation of the asperity
strength. Our model predicts a logarithmic rate dependence of the steady state
shear stress in the quasi-static regime. In the dense flow regime the
frictional strength decreases rapidly with increasing slip rate due to the
effect of thermal softening at the granular interfaces. The transient response
following a step in strain rate includes a direct effect and a following
evolution effect, both of which depend on the magnitude and direction of the
velocity step. In addition to frictional heat, the energy budget includes an
additional energy sink representing the fraction of external work consumed in
increasing local disorder. The model links low-speed and high-speed frictional
response of gouge layers, and provides an essential ingredient for multiscale
modeling of earthquake ruptures with enhanced coseismic weakening.


title:
Long Short-Term Memory Based Recurrent Neural Network Architectures for
  Large Vocabulary Speech Recognition

abstract:
  Long Short-Term Memory (LSTM) is a recurrent neural network (RNN)
architecture that has been designed to address the vanishing and exploding
gradient problems of conventional RNNs. Unlike feedforward neural networks,
RNNs have cyclic connections making them powerful for modeling sequences. They
have been successfully used for sequence labeling and sequence prediction
tasks, such as handwriting recognition, language modeling, phonetic labeling of
acoustic frames. However, in contrast to the deep neural networks, the use of
RNNs in speech recognition has been limited to phone recognition in small scale
tasks. In this paper, we present novel LSTM based RNN architectures which make
more effective use of model parameters to train acoustic models for large
vocabulary speech recognition. We train and compare LSTM, RNN and DNN models at
various numbers of parameters and configurations. We show that LSTM models
converge quickly and give state of the art speech recognition performance for
relatively small sized models.


title:
Conditions for the Existence of Polaron States in Classical Molecular
  Chains at Finite Temperatures

abstract:
  Today in many articles the polaron states are calculated in classical
molecular chains for zero temperature. At the same time it is assumed that
polaron properties do not change significantly, if the temperature is nonzero,
but much smaller than the characteristic energy equal to the depth of the
polaron level. However, the results of computational experiments lead us to
suggestion that in infinitely long chain the polaron is destroyed at any small
different from zero temperature. The paper is devoted to the resolution of
described "paradoxical" situation.


title:
Excitation of Bubbles and Breathers in DNA and Their Interaction with
  the Charge Carriers

abstract:
  The nonlinear excitations induced in DNA by external force are considered on
the basis of Peyrard-Bishop-Dauxois model. It is shown that such impact can
lead to creation of bubbles which can propogate through the molecule. The
interaction of such bubbles with an excess electron or hole is considered. The
numerical experiments demonstrate the possibility of charge transfer induced by
bubbles. The possible applications of the obtained results in
nanobioelectronics are discussed.


title: A positive proportion of plane cubics fail the Hasse principle

abstract:
  When all ternary cubic forms over $\mathbb Z$ are ordered by the heights of
their coefficients, we show that a positive proportion of them fail the Hasse
principle, i.e., they have a zero over every completion of $\mathbb Q$ but no
zero over $\mathbb Q$. We also show that a positive proportion of all ternary
cubic forms over $\mathbb Z$ nontrivially satisfy the Hasse principle, i.e.,
they possess a zero over every completion of $\mathbb Q$ and also possess a
zero over $\mathbb Q$. Analogous results are proven for other genus one models,
namely, for equations of the form $z^2=f(x,y)$ where $f$ is a binary quartic
form over $\mathbb Z$, and for intersections of pairs of quadrics in $\mathbb
P^3$.


title:
Using simple shape three-dimensional inclusions to enhance porous layer
  absorption

abstract:
  The absorption properties of a metaporous material made of non-resonant
simple shape three-dimensional inclusions (cube, cylinder, sphere, cone and
torus) embedded in a rigidly backed rigid frame porous material is studied. A
nearly total absorption can be obtained for a frequency lower than the
quarter-wavelength resonance frequency due to the excitation of a trapped mode.
To be correctly excited, this mode requires a filling fraction larger in the
three-dimensions than in the two-dimensions for purely convex (cube, cylinder,
sphere, and cone) shapes. At low frequencies, a cube is found to be the best
purely convex inclusion shape to embed in a cubic unit cell, while the
embedment of a sphere or a cone cannot lead to an optimal absorption for some
porous materials. At fixed position of purely convex shape inclusion
barycentre, the absorption coefficient only depends on and filling fraction and
does not depend on the shape below the Bragg frequency arising from the
interaction between the inclusion and its image with respect to the rigid
backing. The influence of the angle of incidence is also shown. The results, in
particular the excitation of the trapped mode, are validated experimentally in
case of cubic inclusions.


title: On the Classical Description of Nuclear Motion

abstract:
  Severe methodological and numerical problems of the traditional quantum
mechanical approach to the description of molecular systems are outlined. To
overcome these, a simple alternative to the Born-Oppenheimer approximation is
presented on the basis of taking the nuclei as classical particles.


title:
Size and shape control of magnetite nanoparticles with a nonselective
  binding surfactants

abstract:
  A Martian meteorite, magnetic inks, drug targeting, batteries, contrasts for
MRI, data storage or even clinical thermo-therapy seem to have no connection,
but all have in common a dark mineral called magnetite. However, in each of
these applications this iron oxide shows up with different forms because their
optical, electrical and magnetic properties are strongly dependent on size,
shape and kind of surfactant. In this sense the control of this characteristics
has long been of scientific and technological interest. In an AC magnetic
field-assisted cancer therapy, \textit{e.g.}, from a biological point of view,
the interaction of the nanoparticles with cells is critically determined by the
surface properties which control their fate in biological environments. Besides
the size, factors as the shape also seems to affect the cellular uptake. On the
other hand, the specific absorption rate (SAR) at a fixed frequency and
magnetic field, is hugely dependent on average and distribution of size, shape,
crystalline anisotropy, and degree of aggregation or agglomeration of the
nanoparticles. Each of these factors contributes to an independent energy loss
mechanism: N\'eel relaxation, Brown relaxation or magnetic hysteresis loss.
Thus, the key for improving the efficiency of a given application is the
knowledge about the morphological control.


title: Fuglede-Kadison Determinants and Sofic Entropy

abstract:
  We relate Fuglede-Kadison determinants to entropy of algebraic actions of
sofic groups in essentially complete generality. This generalizes recent
results of Hanfeng Li and Andreas Thom from the amenable case to the sofic
case, as well as results of David Kerr, Hanfeng Li, and Lewis Bowen in the
residually finite case. Moreover, the proof given is the first calculation of
entropy of algebraic actions to avoid a nontrivial determinant approximation.
We apply our results to a problem of Christopher Deninger, generalizing results
of Hanfeng Li and David Kerr. Finally, we show that in many cases, finiteness
of topological entropy for algebraic actions of sofic groups is equivalent to
having metric mean dimension zero.


title: Maximal regularity for non-autonomous evolution equations

abstract:
  We consider the maximal regularity problem for non-autonomous evolution
equations of the form $u(t) + A(t) u(t) = f(t)$ with initial data $u(0) = u\_0$
. Each operator $A(t)$ is associated with a sesquilinear form $a(t; *, *)$ on a
Hilbert space $H$ . We assume that these forms all have the same domain and
satisfy some regularity assumption with respect to t (e.g., piecewise
$\alpha$-H{\"o}lder continuous for some $\alpha\textgreater{} 1/2$). We prove
maximal Lp-regularity for all initial values in the real-interpolation space
$(H, D(A(0)))\_{1/p,p}$ . The particular case where $p = 2$ improves previously
known results and gives a positive answer to a question of J.L. Lions [11] on
the set of allowed initial data $u\_0$ .


title: Security in Cognitive Radio Networks

abstract:
  In this paper, we investigate the information-theoretic security by modeling
a cognitive radio wiretap channel under quality-of-service (QoS) constraints
and interference power limitations inflicted on primary users (PUs). We
initially define four different transmission scenarios regarding channel
sensing results and their correctness. We provide effective secure transmission
rates at which a secondary eavesdropper is refrained from listening to a
secondary transmitter (ST). Then, we construct a channel state transition
diagram that characterizes this channel model. We obtain the effective secure
capacity which describes the maximum constant buffer arrival rate under given
QoS constraints. We find out the optimal transmission power policies that
maximize the effective secure capacity, and then, we propose an algorithm that,
in general, converges quickly to these optimal policy values. Finally, we show
the performance levels and gains obtained under different channel conditions
and scenarios. And, we emphasize, in particular, the significant effect of
hidden-terminal problem on information-theoretic security in cognitive radios.


title: Skew-Gaussian Random Fields

abstract:
  Skewness is often present in a wide range of spatial prediction problems, and
modeling it in the spatial context remains a challenging problem. In this study
a skew-Gaussian random field is considered. The skew-Gaussian random field is
constructed by using the multivariate closed skew-normal distribution, which is
a generalization of the traditional normal distribution. We present a
Metropolis-Hastings algorithm for simulating realizations efficiently from the
random field, and an algorithm for estimating parameters by maximum likelihood
with a Monte Carlo approximation of the likelihood. We demonstrate and evaluate
the algorithms on synthetic cases. The skewness in the skew-Gaussian random
field is found to be strongly influenced by the spatial correlation in the
field, and the parameter estimators appear as consistent with increasing size
of the random field. Moreover, we use the closed skew-normal distribution in a
multivariate random field predictive setting on real seismic data from the
Sleipner field in the North Sea.


title: Gravitational double layers

abstract:
  I analyze the properties of thin shells through which the scalar curvature R
is discontinuous in gravity theories with R + R^2 Lagrangian on the bulk. These
shells/domain walls are of a new kind because they possess, in addition to the
standard energy-momentum tensor, an external energy flux vector, an external
scalar pressure/tension and, most exotic of all, another energy-momentum tensor
contribution resembling classical dipole distributions on a shell: a double
layer. I prove that all these contributions are necessary to make the entire
energy-momentum tensor divergence-free. This is the first known occurrence of
such a type of double layer allowed in a gravity theory. I present explicit
examples in constant-curvature 5-dimensional bulks, with a brief study of their
properties: new physical behaviors arise.


title:
Gravitational Wave Hotspots: Ranking Potential Locations of
  Single-Source Gravitational Wave Emission

abstract:
  The steadily improving sensitivity of pulsar timing arrays (PTAs) suggests
that gravitational waves (GWs) from supermassive black hole binary (SMBHB)
systems in the nearby universe will be de- tectable sometime during the next
decade. Currently, PTAs assume an equal probability of detection from every sky
position, but as evidence grows for a non-isotropic distribution of sources, is
there a most likely sky position for a detectable single source of GWs? In this
paper, a collection of galactic catalogs is used to calculate various metrics
related to the detectability of a single GW source resolv- able above a GW
background, assuming that every galaxy has the same probability of containing a
SMBHB. Our analyses of these data reveal small probabilities that one of these
sources is currently in the PTA band, but as sensitivity is improved regions of
consistent probability density are found in predictable locations, specifically
around local galaxy clusters.


title:
Quantum Cybernetics and Complex Quantum Systems Science - A Quantum
  Connectionist Exploration

abstract:
  Quantum cybernetics and its connections to complex quantum systems science is
addressed from the perspective of complex quantum computing systems. In this
way, the notion of an autonomous quantum computing system is introduced in
regards to quantum artificial intelligence, and applied to quantum artificial
neural networks, considered as autonomous quantum computing systems, which
leads to a quantum connectionist framework within quantum cybernetics for
complex quantum computing systems. Several examples of quantum feedforward
neural networks are addressed in regards to Boolean functions' computation,
multilayer quantum computation dynamics, entanglement and quantum
complementarity. The examples provide a framework for a reflection on the role
of quantum artificial neural networks as a general framework for addressing
complex quantum systems that perform network-based quantum computation,
possible consequences are drawn regarding quantum technologies, as well as
fundamental research in complex quantum systems science and quantum biology.


title: Numerical micromagnetism of strong inhomogeneities

abstract:
  The size of micromagnetic structures, such as domain walls or vortices, is
comparable to the exchange length of the ferromagnet. Both, the exchange length
of the stray field $l_s$ and the magnetocrystalline exchange length $l_k$ are
material-dependent quantities that usually lie in the nanometer range. This
emphasizes the theoretical challenges associated with the mesoscopic nature of
micromagnetism: the magnetic structures are much larger than the atomic lattice
constant, but at the same time much smaller than the sample size. In computer
simulations, the smallest exchange length serves as an estimate for the largest
cell size admissible to prevent appreciable discretization errors. This general
rule is not valid in special situations where the magnetization becomes
particularly inhomogeneous. When such strongly inhomogeneous structures
develop, micromagnetic simulations inevitably contain systematic and numerical
errors. It is suggested to combine micromagnetic theory with a Heisenberg model
to resolve such problems. We analyze cases where strongly inhomogeneous
structures pose limits to standard micromagnetic simulations, arising from
fundamental aspects as well as from numerical drawbacks.


title: Quantum and classical entropic uncertainty relations

abstract:
  How much of the uncertainty in predicting measurement outcomes for
non-commuting quantum observables is genuinely quantum mechanical? We provide a
natural decomposition of the total entropic uncertainty of two non-commuting
observables into a classical component, and an intrinsically quantum mechanical
component. We show that the total quantum component in a state is never lower
or upper bounded by any state-independent quantities, but instead admits
"purity-based" lower bounds that generalize entropic formulations such as the
Maassen-Uffink relation. These relations reveal a non-trivial interplay between
quantum and classical randomness in any finite-dimensional state.


title: Generalized Gaussian Random Fields using hidden selections

abstract:
  We study non-Gaussian random fields constructed by the selection normal
distribution, and we term them selection Gaussian random fields. The selection
Gaussian random field can capture skewness, multi-modality, and to some extend
heavy tails in the marginal distribution. We present a Metropolis-Hastings
algorithm for efficient simulation of realizations from the random field, and a
numerical algorithm for estimating model parameters by maximum likelihood. The
algorithms are demonstrated and evaluated on synthetic cases and on a real
seismic data set from the North Sea. In the North Sea data set we are able to
reduce the mean square prediction error by 20-40% compared to a Gaussian model,
and we obtain more reliable prediction intervals.


title: On a problem by Steklov

abstract:
  We obtain the sharp estimates on the growth of the uniform norm of
orthonormal polynomials for measures satisfying the Steklov condition. This
improves the earlier results by Rakhmanov and completely settles a problem by
Steklov. The sharp estimates for the polynomial entropy in the Steklov class
are obtained as well.


title:
Effective field theory for fluids: Hall viscosity from a
  Wess-Zumino-Witten term

abstract:
  We propose an effective action that describe a relativistic fluid with Hall
viscosity. The construction involves a Wess-Zumino-Witten term that exists only
in (2+1) spacetime dimensions. We note that this formalism can accommodate only
a Hall viscosity which is a homogeneous function of the entropy and particle
number densities of degree one.