title:
Windows Instant Messaging App Forensics: Facebook and Skype as Case
  Studies

abstract:
  Instant messaging (IM) has changed the way people communicate with each
other. However, the interactive and instant nature of these applications (apps)
made them an attractive choice for malicious cyber activities such as phishing.
The forensic examination of IM apps for modern Windows 8.1 (or later) has been
largely unexplored, as the platform is relatively new. In this paper, we seek
to determine the data remnants from the use of two popular Windows Store
application software for instant messaging, namely Facebook and Skype on a
Windows 8.1 client machine. This research contributes to an in-depth
understanding of the types of terrestrial artefacts that are likely to remain
after the use of instant messaging services and application software on a
contemporary Windows operating system. Potential artefacts detected during the
research include data relating to the installation or uninstallation of the
instant messaging application software, log-in and log-off information, contact
lists, conversations, and transferred files.


title:
The period ratio P_1/P_2 of torsional Alfv\'en waves with steady flows
  in spicules

abstract:
  The aim here is to model the standing torsional oscillations in solar
spicules in the presence of density stratification, magnetic field expansion,
and steady flows. By implementing cylindrical geometry, the eigenfrequencies,
eigenfunctions, and the period ratio P_1/P_2 of these waves is obtained for
finite plasma-beta. The shifts created by the steady flow justifies the
divergence of the observed period ratio for the first and second periods from
the number 2.


title: A Quantum Space Behind Simple Quantum Mechanics

abstract:
  In physics, experiments ultimately inform us as to what constitutes a good
theoretical model of any physical concept: physical space should be no
exception. The best picture of physical space in Newtonian physics is given by
the configuration space of a free particle (or the center of mass of a closed
system of particles). This configuration space (as well as phase space), can be
constructed as a representation space for the relativity symmetry. From the
corresponding quantum symmetry, we illustrate the construction of a quantum
configuration space, similar to that of quantum phase space, and recover the
classical picture as an approximation through a contraction of the (relativity)
symmetry and its representations. The quantum Hilbert space reduces into a sum
of one-dimensional representations for the observable algebra, with the only
admissible states given by coherent states and position eigenstates for the
phase and configuration space pictures, respectively. This analysis, founded
firmly on known physics, provides a quantum picture of physical space beyond
that of a finite-dimensional manifold, and provides a crucial first link for
any theoretical model of quantum spacetime at levels beyond simple quantum
mechanics. It also suggests looking at quantum physics from a different
perspective.


title: Numerical Approximation of Hyperbolic Systems Containing an Interface

abstract:
  In this paper we present an approach to approximate numerically the solution
of coupled hyperbolic conservation laws. The coupling is achieved through a
fixed interface, in which interface conditions are linking the traces of both
sides. The numerical solver is based on central methods, like the Rusanov
scheme, and does not use the structure of the Riemann Problem. It consists in
balancing the effects of the waves that enter the interface. The scheme is well
balanced with respect to all the piecewise constant equilibria associated with
the interface condition and is able to maintain exactly conservation properties
of the interface conditions. A detailed analysis and several numerical tests
show the quality of the method. Different applications, including sonic and
transsonic flows and a multiphysic model are studied.


title: Sharp convex bounds on the aggregate sums--An alternative proof

abstract:
  It is well known that a random vector with given marginal distributions is
comonotonic if and only if it has the largest sum with respect to the convex
order [ Kaas, Dhaene, Vyncke, Goovaerts, Denuit (2002), A simple geometric
proof that comonotonic risks have the convex-largest sum, ASTIN Bulletin 32,
71-80. Cheung (2010), Characterizing a comonotonic random vector by the
distribution of the sum of its components, Insurance: Mathematics and Economics
47(2), 130-136] and that a random vector with given marginal distributions is
mutually exclusive if and only if it has the minimal convex sum [Cheung and Lo
(2014), Characterizing mutual exclusivity as the strongest negative
multivariate dependence structure, Insurance: Mathematics and Economics 55,
180-190]. In this note, we give a new proof of this two results using the
theories of distortion risk measure and expected utility.


title: Maxwell problem about thermal sliding of rarefied gas along plate plane

abstract:
  One of classical boundary problems of the kinetic theory (a problem about
thermal sliding) of the rarefied gas along a flat firm surface is considered.
Kinetic Boltzmann equation with model integral of collisions BGK (Bhatnagar,
Gross, Krook) is used. As boundary conditions the boundary Maxwell conditions
(mirror-diffuse) are used. The generalized method of a source is applied to the
problem decision. Comparison with earlier received results is spent.


title:
Minimax theorem for the spectral radius of the product of non-negative
  matrices

abstract:
  We prove the minimax equality for the spectral radius $\rho(AB)$ of the
product of matrices $A\in\mathcal{A}$ and $B\in\mathcal{B}$, where
$\mathcal{A}$ and $\mathcal{B}$ are compact sets of non-negative matrices of
dimensions $N\times M$ and $M\times N$, respectively, satisfying the so-called
hourglass alternative.


title: Operations on Weakly Recognizing Morphisms

abstract:
  Weakly recognizing morphisms from free semigroups onto finite semigroups are
a classical way for defining the class of omega-regular languages, i.e., a set
of infinite words is weakly recognizable by such a morphism if and only if it
is accepted by some B\"uchi automaton. We consider the descriptional complexity
of various constructions for weakly recognizing morphisms. This includes the
conversion from and to B\"uchi automata, the conversion into strongly
recognizing morphisms, and complementation. For some problems, we are able to
give more precise bounds in the case of binary alphabets or simple semigroups.


title: A Lie algebra related to the universal Askey-Wilson algebra

abstract:
  Let $\mathbb{F}$ denote an algebraically closed field. Denote the
three-element set by $\mathcal{X}=\{A,B,C\}$, and let
$\mathbb{F}\left<\mathcal{X}\right>$ denote the free unital associative
$\mathbb{F}$-algebra on $\mathcal{X}$. Fix a nonzero $q\in\mathbb{F}$ such that
$q^4\neq 1$. The universal Askey-Wilson algebra $\Delta$ is the quotient space
$\mathbb{F}\left<\mathcal{X}\right>/\mathbb{I}$, where $\mathbb{I}$ is the
two-sided ideal of $\mathbb{F}\left<\mathcal{X}\right>$ generated by the nine
elements $UV-VU$, where $U$ is one of $A,B,C$, and $V$ is one of
\begin{equation} (q+q^{-1}) A+\frac{qBC-q^{-1}CB}{q-q^{-1}},\nonumber
\end{equation} \begin{equation} (q+q^{-1})
B+\frac{qCA-q^{-1}AC}{q-q^{-1}},\nonumber \end{equation} \begin{equation}
(q+q^{-1}) C+\frac{qAB-q^{-1}BA}{q-q^{-1}}.\nonumber \end{equation} Turn
$\mathbb{F}\left<\mathcal{X}\right>$ into a Lie algebra with Lie bracket
$\left[ X,Y\right] = XY-YX$ for all $X,Y\in\mathbb{F}\left<\mathcal{X}\right>$.
Let $\mathcal{L}$ denote the Lie subalgebra of
$\mathbb{F}\left<\mathcal{X}\right>$ generated by $\mathcal{X}$, which is also
the free Lie algebra on $\mathcal{X}$. Let $L$ denote the Lie subalgebra of
$\Delta$ generated by $A,B,C$. Since the given set of defining relations of
$\Delta$ are not in $\mathcal{L}$, it is natural to conjecture that $L$ is
freely generated by $A,B,C$. We give an answer in the negative by showing that
the kernel of the canonical map
$\mathbb{F}\left<\mathcal{X}\right>\rightarrow\Delta$ has a nonzero
intersection with $\mathcal{L}$. Denote the span of all Hall basis elements of
$\mathcal{L}$ of length $n$ by $\mathcal{L}_n$, and denote the image of
$\sum_{i=1}^n\mathcal{L}_i$ under the canonical map $\mathcal{L}\rightarrow L$
by $L_n$. We study some properties of $L_4$ and $L_5$.


title:
A Commentary on Teichm{\"u}ller's paper ``Vollst{\"a}ndige L{\"o}sung
  einer Extremalaufgabe der quasikonformen Abbildung'' (Complete solution of an
  extremal problem of the quasiconformal mapping)

abstract:
  We comment on Teichm{\"u}ller 's paper ''Vollst{\"a}ndige L{\"o}sung einer
Extremalaufgabe der quasikonformen Abbildung'' (Complete solution of an
ex-tremal problem of the quasiconformal mapping),, published in 1941. In this
paper, Teichm{\"u}ller gives a proof of the existence of extremal
quasiconformal mappings in the case of the pentagon (disc with five
distinguished points on the boundary). The final version of this paper will
appear as a chapter in Volume VI of the Handbook of Teichm{\"u}ller theory.


title:
Hardy spaces on metric measure spaces with generalized sub-gaussian heat
  kernel estimates

abstract:
  Hardy space theory has been studied on manifolds or metric measure spaces
equipped with either Gaussian or sub-Gaussian heat kernel behaviour. However,
there are natural examples where one finds a mix of both behaviour (locally
Gaussian and at infinity sub-Gaussian) in which case the previous theory
doesn't apply. Still we define molecular and square function Hardy spaces using
appropriate scaling, and we show that they agree with Lebesgue spaces in some
range. Besides, counterexamples are given in this setting that the $H^p$ space
corresponding to Gaussian estimates may not coincide with $L ^p$. As a
motivation for this theory, we show that the Riesz transform maps our Hardy
space $H^1$ into $L^1$ .


title: Blow-up phenomena for gradient flows of discrete homogeneous functionals

abstract:
  We investigate gradient flows of some homogeneous functionals in R^N ,
arising in the Lagrangian approximation of systems of self-interacting and
diffusing particles. We focus on the case of negative homogeneity. In the case
of strong self-interaction, the functional possesses a cone of negative energy.
It is immediate to see that solutions with negative energy at some time become
singular in finite time, meaning that a subset of particles concentrate at a
single point. Here, we establish that all solutions become singular in finite
time for the class of functionals under consideration. The paper is completed
with numerical simulations illustrating the striking non linear dynamics when
initial data have positive energy.


title:
Embedding properties of hereditarily just infinite profinite wreath
  products

abstract:
  We study infinitely iterated wreath products of finite permutation groups
with respect to product actions. In particular, we prove that, for every
non-empty class of finite simple groups $\mathcal{X}$, there exists a finitely
generated hereditarily just infinite profinite group $W$ with composition
factors in $\mathcal{X}$ such that any countably based profinite group with
composition factors in $\mathcal{X}$ can be embedded into $W$. Additionally we
investigate when infinitely iterated wreath products of finite simple groups
with respect to product actions are co-Hopfian or non-co-Hopfian.


title:
Calculation of phases of np- scattering for potentials Reid93 and
  Argonne v18 on the phase-function method

abstract:
  A known phase-functions method has been considered for calculation of a
single-channel nucleon-nucleon scattering. The phase shifts of np- scattering
turn out for modern realistic phenomenological nucleon-nucleon potentials
Reid93 but Argonne v18. Influence of choice of numeral method is explored on
the decision of phase equation. For the decision of phase equation as
differential equation of 1th order numeral methods are used: Euler method and
Runge-Kutta methods 2-, 3-, 4- and 5th orders of exactness. Numerically
calculated phase shifts of np- scattering for potentials Reid93 and Argonne v18
are in good agreement with the results obtained with the other methods of
original works. Based on the known phases of scattering one can obtain the full
amplitude, the full cross-section and the partial scattering amplitude
accordingly. The used Runge-Kutta methods can be applied for finding of phases
shifts of the mixed channels of nucleon-nucleon scattering.


title: The lower rank of direct products of hereditarily just infinite groups

abstract:
  We determine the lower rank of the direct product of finitely many
hereditarily just infinite profinite groups of finite lower rank.


title: Maximal linear groups induced on the Frattini quotient of a $p$-group

abstract:
  Let $p>3$ be a prime. For each maximal subgroup $H\leqslant\mathrm{GL}(d,p)$
with $|H| \geqslant p^{3d+1}$, we construct a $d$-generator finite $p$-group
$G$ with the property that $\mathrm{Aut}(G)$ induces $H$ on the Frattini
quotient $G/\Phi(G)$ and $|G| \leqslant p^{\frac{d^4}{2}}$. A significant
feature of this construction is that $|G|$ is very small compared to $|H|$,
shedding new light upon a celebrated result of Bryant and Kov\'acs. The groups
$G$ that we exhibit have exponent $p$, and of all such groups $G$ with the
desired action of $H$ on $G/\Phi(G)$, the construction yields groups with
smallest nilpotency class, and in most cases, the smallest order.


title:
Ghost interaction correction in ensemble density-functional theory for
  excited states with and without range separation

abstract:
  Ensemble density-functional theory (eDFT) suffers from the so-called "ghost
interaction" error when approximate exchange-correlation functionals are used.
In this work, we present a rigorous ghost interaction correction (GIC) scheme
in the context of range-separated eDFT. The method relies on an exact
decomposition of the ensemble short-range exchange-correlation energy into a
multideterminantal exact exchange term, which involves the long-range
interacting ensemble density matrix instead of the Kohn--Sham (KS) one, and a
complementary density-functional correlation energy. A generalized adiabatic
connection formula is derived for the latter. In order to perform practical
calculations, the complementary correlation functional has been simply modeled
by its ground-state local density approximation (LDA) while long-range
interacting ground- and excited-state wavefunctions have been obtained
self-consistently by combining a long-range configuration interaction
calculation with a short-range LDA potential. We show that GIC reduces the
curvature of approximate range-separated ensemble energies drastically while
providing considerably more accurate excitation energies, even for
charge-transfer and double excitations. Interestingly, the method performs well
also in the context of standard KS-eDFT, which is recovered when the
range-separation parameter is set to zero.


title:
Open geometry Fourier modal method: Modeling nanophotonic structures in
  infinite domains

abstract:
  We present an open geometry Fourier modal method based on a new combination
of open boundary conditions and an efficient $k$-space discretization. The open
boundary of the computational domain is obtained using basis functions that
expand the whole space, and the integrals subsequently appearing due to the
continuous nature of the radiation modes are handled using a discretization
based on non-uniform sampling of the $k$-space. We apply the method to a
variety of photonic structures and demonstrate that our method leads to
significantly improved convergence with respect to the number of degrees of
freedom, which may pave the way for more accurate and efficient modeling of
open nanophotonic structures.


title: One-loop Test of Free SU(N) Adjoint Model Holography

abstract:
  We consider the holographic duality where the CFT side is given by $SU(N)$
adjoint free scalar field theory. Compared to the vector models, the set of
single trace operators is immensely extended so that the corresponding AdS
theory also contains infinitely many massive higher spin fields on top of the
massless ones. We compute the one-loop vacuum energy of these AdS fields to
test this duality at the subleading order in large $N$ expansion. The
determination of the bulk vacuum energy requires a proper scheme to sum up the
infinitely many contributions. For that, we develop a new method and apply it
first to calculate the vacuum energies for the first few `Regge trajectories'
in AdS$_4$ and AdS$_5$. In considering the full vacuum energy of AdS theory
dual to a matrix model CFT, we find that there exist more than one available
prescriptions for the one-loop vacuum energy. Taking a particular prescription,
we determine the full vacuum energy of the AdS$_5$ theory, whereas the AdS$_4$
calculation still remains technically prohibitive. This result shows that the
full vacuum energy of the AdS$_5$ theory coincides with minus of the free
energy of a single scalar field on the boundary. This is analogous to the
$O(N)$ vector model case, hence suggests an interpretation of the
\emph{positive} shift of the bulk coupling constant, i.e. from $N^2-1$ to
$N^2$.


title:
The $\Lambda_c(2595)$ resonance as a dynamically generated state: the
  compositeness condition and the large $N_c$ evolution

abstract:
  Recent studies have shown that the well established $\Lambda_c(2595)$
resonance contains a large meson-baryon component, which can vary depending on
the specific formalism. In this work, we examine such a picture by utilizing
the compositeness condition and the large number of colors ($N_c$) expansion.
We examine three different models fulfilling two body unitarity in
coupled-channels, and adopting renormalization schemes where the mass of the
$\Lambda_c(2595)$ resonance is well described, but not necessarily its width,
since we do not consider three body channels and work at the isospin symmetric
limit. Both approximations might have an effect larger on the width than on the
mass. In this context, our studies show that the compositeness of the
$\Lambda_c(2595)$ depends on the number of considered coupled channels, and on
the particular regularization scheme adopted in the unitary approaches and,
therefore, is model dependent. In addition, we perform an exploratory study of
the $\Lambda_c(2595)$ in the large $N_c$ expansion, within a scheme involving
only the $\pi\Sigma_c$ and $K\Xi'_c$ channels, whose dynamics is mostly fixed
by chiral symmetry. In this context and formulating the leading-order
interaction as a function of $N_c$, we show that for moderate $N_c> 3$ values,
the mass and width of the $\Lambda_c(2595)$ deviate from those of a genuine
$qqq$ baryon, implying the relevance of meson-baryon components in its wave
function. Furthermore, we study the properties of the $\Lambda_c(2595)$, in the
strict $N_c \to \infty $ limit, using an extension of the chiral
Weinberg-Tomozawa interaction to an arbitrary number of flavors and colors.
This latter study hints at the possible existence of a (perhaps) sub-dominant
$qqq$ component in the $\Lambda_c(2595)$ resonance wave function, which would
become dominant when the number of colors gets sufficiently large.


title: Non-radial Pulsations in RR Lyrae Stars from the OGLE Collection

abstract:
  RR Lyrae stars are classical pulsating stars. They pulsate mostly in the
radial fundamental mode (RRab stars), in the radial first overtone mode (RRc
stars), or in both modes simultaneously (RRd stars). Collection of variable
stars from the Optical Gravitational Lensing Experiment (OGLE) contains more
than 38 000 RR Lyrae stars from the Galactic bulge. We analysed these data for
RRc and RRd stars. We have found new members of radial-non-radial double-mode
RR Lyrae stars, with characteristic period ratio of the two modes around 0.61.
We increased the number of known RR Lyrae stars of this type by a factor of 8.
We have also discovered another group of double-mode RR Lyrae stars. They
pulsate in the first overtone and in another, unidentified mode, which has
period longer than period of the undetected fundamental mode. The period ratios
tightly cluster around 0.686. These proceedings are focused on this puzzling
group. In particular, we report eight new members of the group.


title: On Contact Numbers of Finite Lattice Sphere Packings of 20-27 Balls

abstract:
  Empirical constructions having maximal contact numbers of unit balls as
putative best ones are presented for 20-27 balls.


title: Mg(OH)2 -WS2 Heterobilayer: Electric Field Tunable Bandgap Crossover

abstract:
  Magnesium hydroxide (Mg(OH)2) has a layered brucite-like structure in its
bulk form and was recently isolated as a new member of 2D monolayer materials.
We investigated the electronic and optical properties of monolayer crystals of
Mg(OH)2 and WS2 and their possible heterobilayer structure by means of first
principles calculations. It was found that both monolayers of Mg(OH)2 and WS 2
are direct-gap semiconductors and these two monolayers form a typical van der
Waals heterostructure with a weak interlayer interaction and a type-II band
alignment with a staggered gap that spatially seperates electrons and holes. We
also showed that an out-of-plane electric field induces a transition from a
staggered to a straddling type heterojunction. Moreover, by solving the
Bethe-Salpeter equation on top of single shot G0 W0 calculations, we show that
the oscillator strength of the intralayer excitons of the heterostructure is an
order of magnitude larger than the oscillator strength of the interlayer
excitons. Because of the staggered interfacial gap and the field- tunable
energy band structure, the Mg(OH)2 -WS2 heterobilayer can become an important
candidate for various optoelectronic device applications in nanoscale.


title:
Anisotropic Ginzburg-Landau scaling of Hc2 and transport properties of
  112-type Ca0.8La0.2Fe0.98Co0.02As2 single crystal

abstract:
  High-quality single crystal of Ca0.8La0.2Fe0.98Co0.02As2 has been
successfully synthesized using a self-flux method. The magnetization
measurement reveals a second peak effect and high critical current density
exceeding 2*10^6 A/cm2 at 5 K(self-field). The upper critical field anisotropy
was systematically studied by measuring the electrical resistivity under
various magnetic fields and angles. The angle dependent magnetoresistance, by
choosing an appropriate anisotropy parameter within the framework of the
anisotropic Ginzburg Landau (AGL) theory, can be scaled onto one single curve.
In the normal state, the negative Hall coefficient shows strong but
nonmonotonic T-dependence through a minimum at 175 K. Moreover, it is shown
that the magnetoresistance apparently violates the semiclassical Kohler's rule
below 175 K but can be well scaled by the Hall angle instead. This suggests
either the change of carriers with T or the exotic anisotropic scattering in
the system.


title:
A comparison between two OLS-based approaches to estimating urban
  multifractal parameters

abstract:
  Multifractal theory provides a new spatial analytical tool to describe urban
form and growth, but many basic problems remain to be solved. Among various
pending issues, the most significant one is how to obtain proper multifractal
dimension spectrums. If an algorithm is improperly used, the parameter values
will be abnormal. This paper is devoted to drawing a comparison between two
OLS-based approaches for estimating urban multifractal parameters. Using
observational data and empirical analysis, we will demonstrate how to utilize
the double logarithmic linear regression to evaluate multifractal parameters.
The OLS regression analysis has two different approaches. One is to fix the
intercept to zero, and the other is not to fix it. The case studies show that
the advisable method is to constrain the intercept to zero. The zero-intercept
regression yields proper multifractal parameter spectrums within certain scale
range of moment order, while the common regression results are not normal. In
practice, the zero-intercept regression and the common regression can be
combined to calculate multifractal parameters. Comparing the two sets of
results, we can judge when and where multifractal urban structure appears. This
research will inspire urban scientists to employ a proper technique to estimate
multifractal dimensions for urban scientific studies.


title:
Trends in magnetism of free Rh clusters via relativistic ab-initio
  calculations

abstract:
  A fully relativistic ab-initio study on free Rh clusters of 13-135 atoms is
performed to identify general trends concerning their magnetism and to check
whether concepts which proved to be useful in interpreting magnetism of 3d
metals are applicable to magnetism of 4d systems. We found that there is no
systematic relation between local magnetic moments and coordination numbers. On
the other hand, the Stoner model appears well-suited both as a criterion for
the onset of magnetism and as a guide for the dependence of local magnetic
moments on the site-resolved density of states at the Fermi level. Large
orbital magnetic moments antiparallel to spin magnetic moments were found for
some sites. The intra-atomic magnetic dipole Tz term can be quite large at
certain sites but as a whole it is unlikely to affect the interpretation of
x-ray magnetic circular dichroism experiments based on the sum rules.


title:
Effective acoustic properties of a meta-material consisting of small
  Helmholtz resonators

abstract:
  We investigate the acoustic properties of meta-materials that are inspired by
sound-absorbing structures. We show that it is possible to construct
meta-materials with frequency-dependent effective properties, with large and/or
negative permittivities. Mathematically, we investigate solutions
$u^\varepsilon: \Omega_\varepsilon \rightarrow \mathbb{R}$ to a Helmholtz
equation in the limit $\varepsilon\rightarrow 0$ with the help of two-scale
convergence. The domain $\Omega_\varepsilon$ is obtained by removing from an
open set $\Omega\subset \mathbb{R}^n$ in a periodic fashion a large number
(order $\varepsilon^{-n}$) of small resonators (order $\varepsilon$). The
special properties of the meta-material are obtained through sub-scale
structures in the perforations.


title: Star formation in a diffuse high-altitude cloud?

abstract:
  A recent discovery of two stellar clusters associated with the diffuse
high-latitude cloud HRK 81.4-77.8 has important implications for star formation
in the Galactic halo. We derive a plausible distance estimate to HRK 81.4-77.8
primarily from its gaseous properties. We spatially correlate state-of-the-art
HI, far-infrared and soft X-ray data to analyze the diffuse gas in the cloud.
The absorption of the soft X-ray emission from the Galactic halo by HRK
81.4-77.8 is used to constrain the distance to the cloud. HRK 81.4-77.8 is most
likely located at an altitude of about 400 pc within the disk-halo interface of
the Milky Way Galaxy. The HI data discloses a disbalance in density and
pressure between the warm and cold gaseous phases. Apparently, the cold gas is
compressed by the warm medium. This disbalance might trigger the formation of
molecular gas high above the Galactic plane on pc to sub-pc scales.


title: Formation and plasma circulation of solar prominences

abstract:
  Solar prominences are long-lived cool and dense plasma curtains in the hot
and rarefied outer solar atmosphere or corona. The physical mechanism
responsible for their formation and especially for their internal plasma
circulation has been uncertain for decades. The observed ubiquitous down flows
in quiescent prominences are difficult to interpret as plasma with high
conductivity seems to move across horizontal magnetic field lines. Here we
present three-dimensional numerical simulations of prominence formation and
evolution in an elongated magnetic flux rope as a result of in-situ plasma
condensations fueled by continuous plasma evaporation from the solar
chromosphere. The prominence is born and maintained in a fragmented, highly
dynamic state with continuous reappearance of multiple blobs and thread
structures that move mainly downward dragging along mass-loaded field lines.
The prominence plasma circulation is characterized by the dynamic balance
between the drainage of prominence plasma back to the chromosphere and the
formation of prominence plasma via continuous condensation. Plasma evaporates
from the chromosphere, condenses into the prominence in the corona, and drains
back to the chromosphere, establishing a stable chromosphere-corona plasma
cycle. Synthetic images of the modeled prominence with the Solar Dynamics
Observatory Atmospheric Imaging Assembly closely resemble actual observations,
with many dynamical threads underlying an elliptical coronal cavity.


title:
A Generic online acceleration scheme for Optimization algorithms via
  Relaxation and Inertia

abstract:
  We propose generic acceleration schemes for a wide class of optimization and
iterative schemes based on relaxation and inertia. In particular, we introduce
methods that automatically tunes the acceleration coefficients online, and
establish their convergence. This is made possible by considering the class of
fixed-points iterations over averaged operators which encompass gradient
methods, ADMM, primal dual algorithms, an so on.


title:
Strong Secrecy in Pairwise Key Agreement over a Generalized Multiple
  Access Channel

abstract:
  This paper considers the problem of pairwise key agreement without public
communication between three users connected through a generalized multiple
access channel (MAC). While two users control the channel inputs, all three
users observe noisy outputs from the channel and each pair of users wishes to
agree on a secret key hidden from the remaining user. We first develop a
"pre-generated" key-agreement scheme based on secrecy codes for the generalized
MAC, in which the channel is only used to distribute pre-generated secret keys.
We then extend this scheme to include an additional layer of rate-limited
secret-key generation by treating the observed channel outputs as induced
sources. We characterize inner and outer bounds on the strong secret-key
capacity region for both schemes. For a special case of the "pre-generated"
scheme, we obtain an exact characterization. We also illustrate with some
binary examples that exploiting the generalized nature of the generalized MAC
may lead to significantly larger key-agreement rates.


title: A survey of HI gas toward the Andromeda Galaxy

abstract:
  The subsequent coalescence of low--mass halos over cosmic time is thought to
be the major formation channel of massive spiral galaxies like the Milky Way
and the Andromeda Galaxy (M31). The gaseous halo of a massive galaxy is
considered to be the reservoir of baryonic matter persistently fueling the star
formation in the disk. Because of its proximity, M31 is the ideal object for
studying the structure of the halo gas in great detail. Using the latest
neutral atomic hydrogen (HI) data of the Effelsberg-Bonn HI Survey (EBHIS)
allows comprising a comprehensive inventory of gas associated with M31. The
primary aim is to differentiate between physical structures belonging to the
Milky Way Galaxy and M31 and accordingly to test the presence of a M31 neutral
gaseous halo. Analyzing the spatially fully sampled EBHIS data makes it
feasible to trace coherent HI structures in space and radial velocity. To
disentangle Milky Way and M31 HI emission we use a new approach, along with the
traditional path of setting an upper radial velocity limit, by calculating a
difference second moment map. We argue that M31's disk is physically connected
to an asymmetric HI halo of tens of kpc size, the M31 cloud. We confirm the
presence of a coherent low-velocity HI filament located in between M31 and M33
aligned at the sky with the clouds at systemic velocity. The physical
parameters of the HI filament are comparable to those of the HI clouds at
systemic velocity. We also detected an irregularly shaped HI cloud that is is
positionally located close to but offset from the stellar body of And XIX.


title:
Representations of cohomological Hall algebras and Donaldson-Thomas
  theory with classical structure groups

abstract:
  We introduce a new class of representations of the cohomological Hall
algebras of Kontsevich and Soibelman, which we call cohomological Hall modules,
or CoHM for short. These representations are constructed from self-dual
representations of a quiver with contravariant involution $\sigma$ and provide
a mathematical model for the space of BPS states in orientifold string theory.
We use the CoHM to define a generalization of the cohomological
Donaldson-Thomas theory of quivers which allows the quiver representations to
have orthogonal and symplectic structure groups. The associated invariants are
called orientifold Donaldson-Thomas invariants. We prove the integrality
conjecture for orientifold Donaldson-Thomas invariants of $\sigma$-symmetric
quivers. We also formulate precise conjectures regarding the geometric meaning
of these invariants and the freeness of the CoHM of a $\sigma$-symmetric
quiver. We prove the freeness conjecture for disjoint union quivers, loop
quivers and the affine Dynkin quiver of type $\widetilde{A}_1$. We also verify
the geometric conjecture in a number of examples. Finally, we describe the CoHM
of finite type quivers by constructing explicit Poincar\'{e}-Birkhoff-Witt type
bases of these representations.


title:
Deterministic submanifolds and analytic solution of the stochastic
  differential master equation describing a qubit

abstract:
  This paper studies the stochastic differential equation (SDE) associated to a
two-level quantum system (qubit) subject to Hamiltonian evolution as well as
unmonitored and monitored decoherence channels. The latter imply a stochastic
evolution of the quantum state (density operator), whose associated probability
distribution we characterize. We first show that for two sets of typical
experimental settings, corresponding either to weak quantum non demolition
measurements or to weak fluorescence measurements, the three Bloch coordinates
of the qubit remain confined to a deterministically evolving surface or curve
inside the Bloch sphere. We explicitly solve the deterministic evolution, and
we provide a closed-form expression for the probability distribution on this
surface or curve. Then we relate the existence in general of such
deterministically evolving submanifolds to an accessibility question of control
theory, which can be answered with an explicit algebraic criterion on the SDE.
This allows us to show that, for a qubit, the above two sets of weak
measurements are essentially the only ones featuring deterministic surfaces or
curves.


title:
Condensation transition in a conserved generalized interacting
  zero-range process

abstract:
  A conserved generalized zero range process is considered in which two sites
interact such that particles hop from the more populated site to the other with
a probability $p$. The steady state particle distribution function $P(n)$ is
obtained using both analytical and numerical methods. The system goes through
several phases as $p$ is varied. In particular, a condensate phase appears for
$p_l < p < p_c$, where the bounding values depend on the range of interaction,
with $p_c < 0.5$ in general. Analysis of $P(n)$ in the condensate phase using a
known scaling form shows there is universal behaviour in the short range
process while the infinite range process displays non-universality. In the
non-condensate phase above $p_c$, two distinct regions are identified: $p_c < p
\leq 0.5$ and $p> 0.5$; a scale emerges in the system in the latter and this
feature is present for all ranges of interaction.


title:
On Axisymmetric and Stationary Solutions of the Self-Gravitating Vlasov
  System

abstract:
  Axisymmetric and stationary solutions are constructed to the Einstein--Vlasov
and Vlasov--Poisson systems. These solutions are constructed numerically, using
finite element methods and a fixed-point iteration in which the total mass is
fixed at each step. A variety of axisymmetric stationary solutions are
exhibited, including solutions with toroidal, disk-like, spindle-like, and
composite spatial density configurations, as are solutions with non-vanishing
net angular momentum. In the case of toroidal solutions, we show for the first
time, solutions of the Einstein--Vlasov system which contain ergoregions.


title:
Deep ALMA imaging of the merger NGC1614 - Is CO tracing a massive inflow
  of non-starforming gas?

abstract:
  Observations of the molecular gas over scales of 0.5 to several kpc provide
crucial information on how gas moves through galaxies, especially in mergers
and interacting systems, where it ultimately reaches the galaxy center,
accumulates, and feeds nuclear activity. Studying the processes involved in the
gas transport is an important step forward to understand galaxy evolution.
12CO, 13CO and C18O1-0 high-sensitivity ALMA observations were used to assess
properties of the large-scale molecular gas reservoir and its connection to the
circumnuclear molecular ring in NGC1614. The role of excitation and abundances
were studied in this context. Spatial distributions of the 12CO and 13CO
emission show significant differences. 12CO traces the large-scale molecular
gas reservoir, associated with a dust lane that harbors infalling gas. 13CO
emission is - for the first time - detected in the large-scale dust lane. Its
emission peaks between dust lane and circumnuclear molecular ring. A
12CO-to-13CO1-0 intensity ratio map shows high values in the ring region (~30)
typical for the centers of luminous galaxy mergers and even more extreme values
in the dust lane (>45). This drop in ratio is consistent with molecular gas in
the dust lane being in a diffuse, unbound state while being funneled towards
the nucleus. We find a high 16O-to-18O abundance ratio in the starburst region
(>900), typical of quiescent disk gas - by now, the starburst is expected to
have enriched the nuclear ISM in 18O relative to 16O. The massive inflow of gas
may be partially responsible for the low 18O/16O abundance since it will dilute
the starburst enrichment with unprocessed gas from greater radii. The
12CO-to-13CO abundance is consistent with this scenario. It suggests that the
nucleus of NGC1614 is in a transient phase of evolution where starburst and
nuclear growth are fuelled by returning gas from the minor merger event.


title: JADE for Tensor-Valued Observations

abstract:
  Independent component analysis is a standard tool in modern data analysis and
numerous different techniques for applying it exist. The standard methods
however quickly lose their effectiveness when the data are made up of
structures of higher order than vectors, namely matrices or tensors (for
example, images or videos), being unable to handle the high amounts of noise.
Recently, an extension of the classic fourth order blind identification (FOBI)
specifically suited for tensor-valued observations was proposed and showed to
outperform its vector version for tensor data. In this paper we extend another
popular independent component analysis method, the joint approximate
diagonalization of eigen-matrices (JADE), for tensor observations. In addition
to the theoretical background we also provide the asymptotic properties of the
proposed estimator and use both simulations and real data to show its
usefulness and superiority over its competitors.


title: Fermentation based carbon nanotube bionic functional composites

abstract:
  The exploitation of the processes used by microorganisms to digest nutrients
for their growth can be a viable method for the formation of a wide range of so
called biogenic materials that have unique mechanical and physical properties
that are not produced by abiotic processes. Based on grape must and bread
fermentation, a bionic composite made of carbon nanotubes (CNTs) and
single-cell fungi, the Saccharomyces cerevisiae yeast extract, was prepared by
fermentation of such microorganisms at room temperature.


title: On the diameter of Kronecker graphs

abstract:
  It is shown that a.a.s. as soon as a Kronecker graph becomes connected its
diameter is bounded by a constant.


title: Decimation of the Dyson-Ising Ferromagnet

abstract:
  We study the decimation to a sublattice of half the sites, of the
one-dimensional Dyson-Ising ferromagnet with slowly decaying long-range pair
interactions of the form $\frac{1}{{|i-j|}^{\alpha}}$, in the phase transition
region (1< $\alpha \leq$ 2, and low temperature). We prove non-Gibbsianness of
the decimated measure at low enough temperatures by exhibiting a point of
essential discontinuity for the finite-volume conditional probabilities of
decimated Gibbs measures. Thus result complements previous work proving
conservation of Gibbsianness for fastly decaying potentials ($\alpha$ > 2) and
provides an example of a "standard" non-Gibbsian result in one dimension, in
the vein of similar resuts in higher dimensions for short-range models. We also
discuss how these measures could fit within a generalized (almost vs. weak)
Gibbsian framework. Moreover we comment on the possibility of similar results
for some other transformations.

categories: math-ph cond-mat.stat-mech math.DS math.MP math.PR


title: Multidimensional Sparse Recovery for MIMO Channel Parameter Estimation

abstract:
  Multipath propagation is a common phenomenon in wireless communication.
Knowledge of propagation path parameters such as complex channel gain,
propagation delay or angle-of-arrival provides valuable information on the user
position and facilitates channel response estimation. A major challenge in
channel parameter estimation lies in its multidimensional nature, which leads
to large-scale estimation problems which are difficult to solve. Current
approaches of sparse recovery for multidimensional parameter estimation aim at
simultaneously estimating all channel parameters by solving one large-scale
estimation problem. In contrast to that we propose a sparse recovery method
which relies on decomposing the multidimensional problem into successive
one-dimensional parameter estimation problems, which are much easier to solve
and less sensitive to off-grid effects, while providing proper parameter
pairing. Our proposed decomposition relies on convex optimization in terms of
nuclear norm minimization and we present an efficient implementation in terms
of the recently developed STELA algorithm.


title:
Comparative Density Functional Theory and Density Functional Tight
  Binding Study of Arginine and Arginine-Rich Cell-Penetrating Peptide TAT
  Adsorption on Anatase TiO2

abstract:
  We present a comparative Density Functional Theory (DFT) and Density
Functional Tight Binding (DFTB) study of geometries and electronic structures
of arginine (Arg), arginine adsorbed on the anatase (101) surface of titania in
several adsorption configurations, and of an arginine-rich cell penetrating
peptide TAT and its adsorption on the surface of TiO2. Two DFTB
parameterizations are considered, tiorg-0-1/mio-1-1 and matsci-0-3. While there
is good agreement in the structures and relative energies of Arg and peptide
conformers between DFT and DFTB, both adsorption geometries and energies are
noticeably different for Arg adsorbed on TiO2. The tiorg-0-1/mio-1-1
parameterization performs better than matsci-0-3. We relate this difference to
the difference in electronic structures resulting from the two methods (DFT and
DFTB) and specifically to the band alignment between the molecule and the
oxide. We show that the band alignment of TAT and of TiO2 modeled with DFTB is
qualitatively correct but that with DFT using the PBE functional is not. This
is specific to the modeling of large molecules where the HOMO is close to the
conduction band of the oxide. We therefore report a case where the approximate
DFT-based method - DFTB (with which the correct band structure can be
effectively obtained) - performs better than the DFT itself with a functional
approximation feasible for the modeling of large bio-inorganic interfaces, i.e.
GGA (as opposed to hybrid functionals which are impractical at such a scale).
Our results highlight the utility of the DFTB method for the modeling of
bioinorganic interfaces not only from the CPU cost perspective but also from
the accuracy point of view.


title: Online semi-parametric learning for inverse dynamics modeling

abstract:
  This paper presents a semi-parametric algorithm for online learning of a
robot inverse dynamics model. It combines the strength of the parametric and
non-parametric modeling. The former exploits the rigid body dynamics equa-
tion, while the latter exploits a suitable kernel function. We provide an
extensive comparison with other methods from the literature using real data
from the iCub humanoid robot. In doing so we also compare two different
techniques, namely cross validation and marginal likelihood optimization, for
estimating the hyperparameters of the kernel function.


title:
MATISSE: A novel tool to access, visualize and analyse data from
  planetary exploration missions

abstract:
  The increasing number and complexity of planetary exploration space missions
require new tools to access, visualize and analyse data to improve their
scientific return.
  ASI Science Data Center (ASDC) addresses this request with the web-tool
MATISSE (Multi-purpose Advanced Tool for the Instruments of the Solar System
Exploration), allowing the visualization of single observation or real-time
computed high-order products, directly projected on the three-dimensional model
of the selected target body.
  Using MATISSE it will be no longer needed to download huge quantity of data
or to write down a specific code for every instrument analysed, greatly
encouraging studies based on joint analysis of different datasets.
  In addition the extremely high-resolution output, to be used offline with a
Python-based free software, together with the files to be read with specific
GIS software, makes it a valuable tool to further process the data at the best
spatial accuracy available.
  MATISSE modular structure permits addition of new missions or tasks and,
thanks to dedicated future developments, it would be possible to make it
compliant to the Planetary Virtual Observatory standards currently under
definition. In this context the recent development of an interface to the NASA
ODE REST API by which it is possible to access to public repositories is set.


title: Variable-Length Hashing

abstract:
  Hashing has emerged as a popular technique for large-scale similarity search.
Most learning-based hashing methods generate compact yet correlated hash codes.
However, this redundancy is storage-inefficient. Hence we propose a lossless
variable-length hashing (VLH) method that is both storage- and
search-efficient. Storage efficiency is achieved by converting the fixed-length
hash code into a variable-length code. Search efficiency is obtained by using a
multiple hash table structure. With VLH, we are able to deliberately add
redundancy into hash codes to improve retrieval performance with little
sacrifice in storage efficiency or search complexity. In particular, we propose
a block K-means hashing (B-KMH) method to obtain significantly improved
retrieval performance with no increase in storage and marginal increase in
computational cost.


title: Real Analyticity for random dynamics of transcendental functions

abstract:
  Analyticity results of expected pressure and invariant densities in the
context of random dynamics of transcendental functions are established. These
are obtained by a refinement of work by Rugh leading to a simple approach to
analyticity. We work under very mild dynamical assumptions. Just the iterates
of the Perron-Frobenius operator are assumed to converge.
  We also provide a Bowen's formula expressing the almost sure Hausdorff
dimension of the radial fiberwise Julia sets in terms of the zero of an
expected pressure function. Our main application states real analyticity for
the variation of this dimension for suitable hyperbolic random systems of
entire or meromorphic functions.


title: Estimation of inverse autocovariance matrices for long memory processes

abstract:
  This work aims at estimating inverse autocovariance matrices of long memory
processes admitting a linear representation. A modified Cholesky decomposition
is used in conjunction with an increasing order autoregressive model to achieve
this goal. The spectral norm consistency of the proposed estimate is
established. We then extend this result to linear regression models with
long-memory time series errors. In particular, we show that when the objective
is to consistently estimate the inverse autocovariance matrix of the error
process, the same approach still works well if the estimated (by least squares)
errors are used in place of the unobservable ones. Applications of this result
to estimating unknown parameters in the aforementioned regression model are
also given. Finally, a simulation study is performed to illustrate our
theoretical findings.


title:
Probing the multi-scale interplay between gravity and turbulence -
  Power-law like gravitational energy spectra of the Orion Complex

abstract:
  Gravity plays a determining role in the evolution of the molecular ISM. In
\citet{2016arXiv160304342L}, we proposed a measure called gravitational energy
spectrum to quantify the importance of gravity on multiple physical scales. In
this work, using a wavelet-based decomposition technique, we derive the
gravitational energy spectra of the Orion A and the Orion B molecular cloud
from observational data. The gravitational energy spectra exhibit
power-law-like behaviours. From a few pc down to $\sim 0.1 $ pc scale, the
Orion A and Orion B molecular cloud have $E_{\rm p}(k)\sim k^{-1.88}$ and
$E_{\rm p}(k)\sim k^{-2.09}$, respectively. These scaling exponents are close
to the scaling exponents of the kinetic energy power spectrum of compressible
turbulence (where $E\sim k^{-2}$), with a near-equipartition of turbulent
versus gravitational energy on multiple scales. This provides a clear evidence
that gravity is able to counteract effectively against turbulent motion for
these length scales. The results confirm our earlier analytical estimates. For
the Orion A molecular cloud, gravity inevitably dominates over turbulence
inside the cloud. Our results provide a clear observational proof that gravity
is playing a determining role in the evolution these molecular clouds from the
cloud scale down to $\sim 0.1\;\rm pc$. { However, turbulence is likely to
dominate in clouds like California. } The method is general and should be
applicable to all the astrophysical problems where gravity plays a role.


title:
Analytical Models of Exoplanetary Atmospheres. III. Gaseous C-H-O-N
  Chemistry with 9 Molecules

abstract:
  We present novel, analytical, equilibrium-chemistry formulae for the
abundances of molecules in hot exoplanetary atmospheres that include the
carbon, oxygen and nitrogen networks. Our hydrogen-dominated solutions involve
acetylene (C$_2$H$_2$), ammonia (NH$_3$), carbon dioxide (CO$_2$), carbon
monoxide (CO), ethylene (C$_2$H$_4$), hydrogen cyanide (HCN), methane (CH$_4$),
molecular nitrogen (N$_2$) and water (H$_2$O). By considering only the gas
phase, we prove that the mixing ratio of carbon monoxide is governed by a decic
equation (polynomial equation of degree 10). We validate our solutions against
numerical calculations of equilibrium chemistry that perform Gibbs free energy
minimization and demonstrate that they are accurate at the $\sim 1\%$ level for
temperatures from 500 to 3000 K. In hydrogen-dominated atmospheres, the ratio
of abundances of HCN to CH$_4$ is nearly constant across a wide range of
carbon-to-oxygen ratios, which makes it a robust diagnostic of the metallicity
in the gas phase. Our validated formulae allow for the convenient benchmarking
of chemical kinetics codes and provide an efficient way of enforcing chemical
equilibrium in atmospheric retrieval calculations.


title:
Proposal of a micromagnetic standard problem for ferromagnetic resonance
  simulations

abstract:
  Nowadays, micromagnetic simulations are a common tool for studying a wide
range of different magnetic phenomena, including the ferromagnetic resonance. A
technique for evaluating reliability and validity of different micromagnetic
simulation tools is the simulation of proposed standard problems. We propose a
new standard problem by providing a detailed specification and analysis of a
sufficiently simple problem. By analyzing the magnetization dynamics in a thin
permalloy square sample, triggered by a well defined excitation, we obtain the
ferromagnetic resonance spectrum and identify the resonance modes via Fourier
transform. Simulations are performed using both finite difference and finite
element numerical methods, with \textsf{OOMMF} and \textsf{Nmag} simulators,
respectively. We report the effects of initial conditions and simulation
parameters on the character of the observed resonance modes for this standard
problem. We provide detailed instructions and code to assist in using the
results for evaluation of new simulator tools, and to help with numerical
calculation of ferromagnetic resonance spectra and modes in general.


title:
On the interaction of uni-directional and bi-directional buckling of a
  plate supported by an elastic foundation

abstract:
  A thin flat rectangular plate supported on its edges and subjected to
in-plane loading exhibits stable post-buckling behaviour. However, the
introduction of a nonlinear (softening) elastic foundation may cause the
response to become unstable. Here the post-buckling of such a structure is
investigated and several important phenomena are identified, including the
transition of patterns from stripes to spots and back again. The interaction
between these forms is of importance for understanding the possible
post-buckling behaviours of this structural system. In addition, both periodic
and some localized responses are found to exist as the dimensions of the plate
are increased and this becomes relevant when the characteristic wavelengths of
the buckle pattern are small compared to the size of the plate. Potential
application of the model range from macroscopic industrial manufacturing of
structural elements to the understanding of micro- and nano-scale deformations
in materials.


title: Surfactant-Free Single Layer Graphene in Water

abstract:
  Dispersing graphite in water to obtain true (single layer) graphene (SLG) in
bulk quantity in a liquid has been an unreachable goal for materials scientists
in the last decade. Likewise, a diagnostic tool for identifying solubilized SLG
in situ has been long awaited. Homogeneous stable dispersions of SLG in water
are obtained by mixing graphenide (negatively charged graphene) solutions in
tetrahydrofuran (THF) with degassed water and evaporating the organic solvent.
In situ Raman spectroscopy of these aqueous dispersions shows all the expected
characteristics of single layer graphene, including an intense 2D band of
Lorentzian shape and linewidth of 28 cm-1. Transmission electron and atomic
force microscopies on deposits confirm SLG character. The resulting
additive-free stable water dispersions contain 0.16 mg/mL of SLG.


title: Set Containment Join Revisited

abstract:
  Given two collections of set objects $R$ and $S$, the $R \bowtie_{\subseteq}
S$ set containment join returns all object pairs $(r, s) \in R \times S$ such
that $r \subseteq s$. Besides being a basic operator in all modern data
management systems with a wide range of applications, the join can be used to
evaluate complex SQL queries based on relational division and as a module of
data mining algorithms. The state-of-the-art algorithm for set containment
joins (PRETTI) builds an inverted index on the right-hand collection $S$ and a
prefix tree on the left-hand collection $R$ that groups set objects with common
prefixes and thus, avoids redundant processing. In this paper, we present a
framework which improves PRETTI in two directions. First, we limit the prefix
tree construction by proposing an adaptive methodology based on a cost model;
this way, we can greatly reduce the space and time cost of the join. Second, we
partition the objects of each collection based on their first contained item,
assuming that the set objects are internally sorted. We show that we can
process the partitions and evaluate the join while building the prefix tree and
the inverted index progressively. This allows us to significantly reduce not
only the join cost, but also the maximum memory requirements during the join.
An experimental evaluation using both real and synthetic datasets shows that
our framework outperforms PRETTI by a wide margin.


title:
Irreconcilable Difference Between Quantum Walks and Adiabatic Quantum
  Computing

abstract:
  Continuous-time quantum walks and adiabatic quantum evolution are two general
techniques for quantum computing, both of which are described by Hamiltonians
that govern their evolutions by Schr\"odinger's equation. In the former, the
Hamiltonian is fixed, while in the latter, the Hamiltonian varies with time. As
a result, their formulations of Grover's algorithm evolve differently through
Hilbert space. We show that this difference is fundamental; they cannot be made
to evolve along each other's path without introducing structure more powerful
than the standard oracle for unstructured search. For an adiabatic quantum
evolution to evolve like the quantum walk search algorithm, it must interpolate
between three fixed Hamiltonians, one of which is complex and introduces
structure that is stronger than the oracle for unstructured search. Conversely,
for a quantum walk to evolve along the path of the adiabatic search algorithm,
it must be a chiral quantum walk on a weighted, directed star graph with
structure that is also stronger than the oracle for unstructured search. Thus
the two techniques, although similar in being described by Hamiltonians that
govern their evolution, compute by fundamentally irreconcilable means.


title: Q-tensor square of finitely generated nilpotent groups, q >= 0

abstract:
  The authors extend to the $q-$tensor square $G \otimes^q G$ of a group $G$,
$q$ a non-negative integer, some structural results due to R. D. Blyth, F.
Fumagalli and M. Morigi concerning the non-abelian tensor square $G \otimes G$
($q = 0$). The results are applied to the computation of $G \otimes^q G$ for
finitely generated nilpotent groups $G$, specially for free nilpotent groups of
finite rank. They also generalize to all $q \geq 0$ results of M. Bacon
regarding an upper bound to the minimal number of generators of the non-abelian
tensor square $G \otimes G$ when $G$ is a $n-$generator nilpotent group of
class 2. The paper ends with the computation of the $q-$tensor squares of the
free $n-$generator nilpotent group of class 2, $n \geq 2$, for all $q \geq 0.$
This shows that the above mentioned upper bound is also achieved for these
groups when $q > 1.$


title:
Linear and nonlinear magneto-optical rotation on the narrow strontium
  intercombination line

abstract:
  In the presence of an external static magnetic field, an atomic gas becomes
optically active, showing magneto-optical rotation. In the saturated regime,
the coherences among the excited substates give a nonlinear contribution to the
rotation of the light polarization. In contrast with the linear magneto-optical
rotation, the nonlinear counterpart is insensitive to Doppler broadening. By
varying the temperature of a cold strontium gas, we observe both regimes by
driving the $J=0\rightarrow J=1$ transition on the intercombination line. For
this narrow transition, the sensitivity to the static magnetic field is
typically three orders of magnitude larger than for a standard broad alkali
transition.


title: A Short Note on Infinite Union/Intersection of Omega Regular Languages

abstract:
  We in this paper show that omega regular languages are not closed under
infinite union and intersection. As an attempt, we propose to add step
variables and quantifiers to temporal logics to enhance the expressiveness of
the underlying logic. We also show that doing this would cause undecidability
in satisfiability, even if for a rather limited fragment of temporal logic.


title:
Large scale GW-BSE calculations with N3 scaling: excitonic effects in
  dye sensitised solar cells

abstract:
  Excitonic effects due to electron-hole coupling play a fundamental role in
renormalising energy levels in dye sensitised and organic solar cells
determining the driving force for electron extraction. We show that
first-principles calculations based on many-body perturbation theory within the
GW-BSE approach provide a quantitative picture of interfacial excited state
energetics in organic dye-sensitized TiO2 , delivering a general rule for
evaluating relevant energy levels.To perform GW-BSE calculations in such large
systems we introduce a new scheme based on maximally localized Wannier
functions. With this method the overall scaling of GW-BSE calculations is
reduced from O(N4) to O(N3).


title:
Relativistic Corrections for Time and Frequency Transfer in Optical
  Fibres

abstract:
  We derive relativistic corrections for one-way and two-way time and frequency
transfer over optical fibres neglecting no terms that exceed 1 ps in time and
$10^{-18}$ in fractional frequency, and estimate their magnitude in typical
fibre links. We also provide estimates of the uncertainties in the evaluation
of the relativistic corrections due to imperfect knowledge of parameters like
the coordinates of the fibre and stations, Earth rotation, or thermal effects
of the fibre index and length. The links between Teddington(UK) and Paris(F) as
well as Braunschweig(D) and Paris(F), that are currently under construction,
are studied as specific examples.


title: Client-Waiter games on complete and random graphs

abstract:
  For a graph G, a monotone increasing graph property P and positive integer q,
we define the Client-Waiter game to be a two-player game which runs as follows.
In each turn Waiter is offering Client a subset of at least one and at most q+1
unclaimed edges of G from which Client claims one, and the rest are claimed by
Waiter. The game ends when all the edges have been claimed. If Client's graph
has property P by the end of the game, then he wins the game, otherwise Waiter
is the winner. In this paper we study several Client-Waiter games on the edge
set of the complete graph, and the H-game on the edge set of the random graph.
For the complete graph we consider games where Client tries to build a large
star, a long path and a large connected component. We obtain lower and upper
bounds on the critical bias for these games and compare them with the
corresponding Waiter-Client games and with the probabilistic intuition. For the
H-game on the random graph we show that the known results for the corresponding
Maker-Breaker game are essentially the same for the Client-Waiter game, and we
extend those results for the biased games and for trees.


title: Sum of squares length of real forms

abstract:
  For $n,\,d\ge1$ let $p(n,2d)$ denote the smallest number $p$ such that every
sum of squares of forms of degree $d$ in $\mathbb{R}[x_1,\dots,x_n]$ is a sum
of $p$ squares. We establish lower bounds for these numbers that are
considerably stronger than the bounds known so far. Combined with known upper
bounds they give $p(3,2d)\in\{d+1,\,d+2\}$ in the ternary case. Assuming a
conjecture of Iarrobino-Kanev on dimensions of tangent spaces to catalecticant
varieties, we show that $p(n,2d)\sim const\cdot d^{(n-1)/2}$ for $d\to\infty$
and all $n\ge3$. For ternary sextics and quaternary quartics we determine the
exact value of the invariant, showing $p(3,6)=4$ and $p(4,4)=5$.


title: Simple Homotopy Equivalence of Nearby Lagrangians

abstract:
  Given a closed exact Lagrangian in the cotangent bundle of a closed smooth
manifold, we prove that the projection to the base is a simple homotopy
equivalence.


title:
Stationary light pulses and narrowband light storage in a laser-cooled
  ensemble loaded into a hollow-core fiber

abstract:
  We report on the first observation of stationary light pulses and narrowband
light storage inside a hollow-core photonic crystal fiber. Laser-cooled atoms
were first loaded into the fiber core providing strong light-matter coupling.
Light pulses were then stored in a collective atomic excitation using a single
control laser beam. By applying a second counterpropagating control beam, a
light pulse could be brought to a standstill. Our work paves the way towards
the creation of strongly-correlated many-body systems with photons and
applications in the field of quantum information processing.


title: Degree reduction of composite B\'ezier curves

abstract:
  This paper deals with the problem of multi-degree reduction of a composite
B\'ezier curve with the parametric continuity constraints at the endpoints of
the segments. We present a novel method which is based on the idea of using
constrained dual Bernstein polynomials to compute the control points of the
reduced composite curve. In contrast to other methods, ours minimizes the
$L_2$-error for the whole composite curve instead of minimizing the
$L_2$-errors for each segment separately. As a result, an additional
optimization is possible. Examples show that the new method gives much better
results than multiple application of the degree reduction of a single B\'ezier
curve.


title: H-exponential change of Finsler metric

abstract:
  In this paper, we studied a Finsler space whose metric is given by an
h-exponential change and obtain the Cartan connection coefficients for the
change. We also find the necessary and sufficient condition for an
h-exponential change of Finsler metric to be projective.


title: Modified Group Delay Based MultiPitch Estimation in Co-Channel Speech

abstract:
  Phase processing has been replaced by group delay processing for the
extraction of source and system parameters from speech. Group delay functions
are ill-behaved when the transfer function has zeros that are close to unit
circle in the z-domain. The modified group delay function addresses this
problem and has been successfully used for formant and monopitch estimation. In
this paper, modified group delay functions are used for multipitch estimation
in concurrent speech. The power spectrum of the speech is first flattened in
order to annihilate the system characteristics, while retaining the source
characteristics. Group delay analysis on this flattened spectrum picks the
predominant pitch in the first pass and a comb filter is used to filter out the
estimated pitch along with its harmonics. The residual spectrum is again
analyzed for the next candidate pitch estimate in the second pass. The final
pitch trajectories of the constituent speech utterances are formed using pitch
grouping and post processing techniques. The performance of the proposed
algorithm was evaluated on standard datasets using two metrics; pitch accuracy
and standard deviation of fine pitch error. Our results show that the proposed
algorithm is a promising pitch detection method in multipitch environment for
real speech recordings.


title:
A note on classification of proper teleparallel conformal symmetries of
  spherically symmetric static space-times in the teleparallel theory of
  gravitation using diagonal tetrads

abstract:
  A study of proper teleparallel conformal vector field in spherically
symmetric static space-times is given using the direct integration technique
and diagonal tetrads. In this study we show that the above space-times do not
admit proper teleparallel conformal vector fields.


title:
An It\^o calculus for a class of limit processes arising from random
  walks on the complex plane

abstract:
  Within the framework of the previous paper [8]. we develop a generalized
stochastic calculus for processes associated to higher order diffusion
operators. Applications to the study of a Cauchy problem, a Feynman-Kac formula
and a representation formula for higher derivatives of analytic functions are
also given.


title:
Observing "Quantized" Conductance Steps in Silver Sulfide: Two Parallel
  Resistive Switching Mechanisms

abstract:
  We demonstrate that it is possible to distinguish two conductance switching
mechanisms in silver sulfide devices at room temperature. Experiments were
performed using a Ag$_2$S thin film deposited on a wide Ag bottom electrode,
which was contacted by the Pt tip of a scanning tunneling microscope. By
applying a positive voltage on the silver electrode the conductance is seen to
switch to a state having three orders of magnitude higher conductance, which is
related to the formation of a conductive path inside the Ag$_2$S thin film. We
argue this to be composed of a metallic silver nanowire accompanied by a
modification of the surrounding lattice structure. Metallic silver nanowires
decaying after applying a negative voltage allow observing conductance steps in
the breaking traces characteristic for atomic-scale contacts, while the lattice
structure deformation is revealed by gradual and continuously decreasing
conductance traces.


title:
Two-photon double ionization of neon using an intense attosecond pulse
  train

abstract:
  We present the first demonstration of two-photon double ionization of neon
using an intense extreme ultraviolet (XUV) attosecond pulse train (APT) in a
photon energy regime where both direct and sequential mechanisms are allowed.
For an APT generated through high-order harmonic generation (HHG) in argon we
achieve a total pulse energy close to 1 $\mu$J, a central energy of 35 eV and a
total bandwidth of $\sim30$ eV. The APT is focused by broadband optics in a
neon gas target to an intensity of $3\cdot10^{12} $W$\cdot$cm$^{-2}$. By tuning
the photon energy across the threshold for the sequential process the double
ionization signal can be turned on and off, indicating that the two-photon
double ionization predominantly occurs through a sequential process. The
demonstrated performance opens up possibilities for future XUV-XUV pump-probe
experiments with attosecond temporal resolution in a photon energy range where
it is possible to unravel the dynamics behind direct vs. sequential double
ionization and the associated electron correlation effects.


title: Aging Wiener-Khinchin Theorem and Critical Exponents of $1/f$ Noise

abstract:
  The power spectrum of a stationary process may be calculated in terms of the
autocorrelation function using the Wiener-Khinchin theorem. We here generalize
the Wiener-Khinchin theorem for nonstationary processes and introduce a
time-dependent power spectrum $\left\langle S_{t_m}(\omega)\right\rangle$ where
$t_m$ is the measurement time. For processes with an aging correlation function
of the form $\left\langle I(t)I(t+\tau)\right\rangle=t^{\Upsilon}\phi_{\rm
EA}(\tau/t)$, where $\phi_{\rm EA}(x)$ is a nonanalytic function when $x$ is
small, we find aging $1/f$ noise. Aging $1/f$ noise is characterized by five
critical exponents. We derive the relations between the scaled correlation
function and these exponents. We show that our definition of the time-dependent
spectrum retains its interpretation as a density of Fourier modes and discuss
the relation to the apparent infrared divergence of $1/f$ noise. We illustrate
our results for blinking quantum dot models, single-file diffusion and Brownian
motion in logarithmic potential.


title:
Nonlocal Symmetries and Interaction Solutions of the (2+1)-dimensional
  Higher Order Broer-Kaup System

abstract:
  The (2+1)-dimensional higher-order Broer-Kaup (HBK) system is studied by
nonlocal symmetry method and consistent tanh expansion (CTE) method in this
paper. Some exact interaction solutions among different nonlinear excitations
such as solitons, rational waves, periodic waves and corresponding images are
explicitly given.


title:
Kinetic modeling of detonation and effects of negative temperature
  coefficient

abstract:
  The kinetic modeling and simulation of reactive flows, especially for those
with detonation, are further investigated. From the theoretical side, a new set
of hydrodynamic equations are deduced, where the viscous stress tensor and heat
flux are replaced by two non-equilibrium quantities that have been defined in
our previous work. The two non-equilibrium quantities are referred to as
NonOrganized Momentum Flux (NOMF) and Non-Organized Energy Flux (NOEF),
respectively, here. The numerical results of viscous stress (heat flux) have a
good agreement with those of NOMF (NOEF) near equilibrium state. Around sharp
interfaces, the values of NOMF (NOEF) deviate reasonably from those of viscous
stress (heat flux). Based on this hydrodynamic model, the relations between the
two non-equilibrium quantities and entropy productions are established. Based
on the discrete Boltzmann model, four kinds of detonation phenomena with
different reaction rates, including Negative Temperature Coefficient (NTC)
regime, are simulated and investigated. The differences of the four kinds of
detonations are studied from three aspects: hydrodynamic quantities,
non-equilibrium quantities and entropy productions.


title:
Optimal strategies for observation of active galactic nuclei variability
  with Imaging Atmospheric Cherenkov Telescopes

abstract:
  Variable emission is one of the defining characteristic of active galactic
nuclei (AGN). While providing precious information on the nature and physics of
the sources, variability is often challenging to observe with time- and
field-of-view-limited astronomical observatories such as Imaging Atmospheric
Cherenkov Telescopes (IACTs). In this work, we address two questions relevant
for the observation of sources characterized by AGN-like variability: what is
the most time-efficient way to detect such sources, and what is the
observational bias that can be introduced by the choice of the observing
strategy when conducting blind surveys of the sky. Different observing
strategies are evaluated using simulated light curves and realistic instrument
response functions of the Cherenkov Telescope Array (CTA), a future gamma-ray
observatory. We show that strategies that makes use of very small observing
windows, spread over large periods of time, allows for a faster detection of
the source, and are less influenced by the variability properties of the
sources, as compared to strategies that concentrate the observing time in a
small number of large observing windows. Although derived using CTA as an
example, our conclusions are conceptually valid for any IACTs facility, and in
general, to all observatories with small field of view and limited duty cycle.


title: On the axiomatizability of $\mathrm{C}^*$-algebras as operator systems

abstract:
  We show that the class of unital $\mathrm{C}^*$-algebras is an elementary
class in the language of operator systems. As a result, we have that there is a
definable predicate in the language of operator systems that defines the
multiplication in any $\mathrm{C}^*$-algebra. Moreover, we prove that the
aforementioned class is $\forall\exists\forall$-axiomatizable but not
$\forall\exists$-axiomatizable nor $\exists\forall$-axiomatizable.


title:
Particle-based Gaussian process optimization for input design in
  nonlinear dynamical models

abstract:
  We propose a novel approach to input design for identification of nonlinear
state space models. The optimal input sequence is obtained by maximizing a
scalar cost function of the Fisher information matrix. Since the Fisher
information matrix is unavailable in closed form, it is estimated using
particle methods. In addition, we make use of Gaussian process optimization to
find the optimal input and to mitigate the problem of a large computational
cost incurred by the particle filter, as the method reduces the number of
functional evaluations. Numerical examples are provided to illustrate the
performance of the resulting algorithm.


title: Electromechanical power flowcharts in systems of electrical circuits

abstract:
  We present an original undergraduate level compilation for the physics of
electromechanical systems with special attention to power flow. An approach
based on energy considerations is presented that is specially suited to compute
the mechanical and electrical actions of electromagnetic fields and to draw
power flowcharts that clarify the path taken by energy in typical devices. The
procedure guarantees energy conservation and provides a consistent way for
auditing the power flow.


title:
Generation of mechanical force by grafted polyelectrolytes in an
  electric field

abstract:
  We study theoretically and by means of molecular dynamics (MD) simulations
the generation of mechanical force by grafted polyelectrolytes in an external
electric field, which favors its adsorption on the grafting plane. The force
arises in deformable bodies linked to the free end of the chain. Varying the
field, one controls the length of the non-adsorbed part of the chain and hence
the deformation of the target body, i.e., the arising force too. We consider
target bodies with a linear force-deformation relation and with a Hertzian one.
While the first relation models a coiled Gaussian chain, the second one
describes the force response of a squeezed colloidal particle. The theoretical
dependencies of generated force and compression of the target body on applied
field agree very well with the results of MD simulations. The analyzed
phenomenon may play an important role in a future nano-machinery, e.g. it may
be used to design nano-vices to fix nano-sized objects.


title: Cofibrant objects in the Thomason Model Structure

abstract:
  There are Quillen equivalent Thomason model structures on the category of
small categories, the category of small acyclic categories and the category of
posets. These share the property that cofibrant objects are posets. In fact,
they share the same class of cofibrant objects. We show that every finite
semilattice, every chain, every countable tree, every finite zigzag and every
poset with five or less elements is cofibrant in all of those structures.


title: Limits of time in cosmology

abstract:
  We provide a discussion of some main ideas in our project about the physical
foundation of the time concept in cosmology. It is standard to point to the
Planck scale (located at $\sim 10^{-43}$ seconds after a fictitious "Big Bang"
point) as a limit for how far back we may extrapolate the standard cosmological
model. In our work we have suggested that there are several other (physically
motivated) interesting limits -- located at least thirty orders of magnitude
before the Planck time -- where the physical basis of the cosmological model
and its time concept is progressively weakened. Some of these limits are
connected to phase transitions in the early universe which gradually undermine
the notion of 'standard clocks' widely employed in cosmology. Such
considerations lead to a 'scale problem' for time which becomes particularly
acute above the electroweak phase transition (before $\sim 10^{-11}$ seconds).
Other limits are due to problems of building up a cosmological reference frame,
or even contemplating a sensible notion of proper time, if the early universe
constituents become too quantum. This 'quantum problem' for time arises e.g. if
a pure quantum phase is contemplated at the beginning of inflation at, say,
$\sim 10^{-34}$ seconds.

categories: gr-qc astro-ph.CO hep-th physics.hist-ph quant-ph


title: Characterization of Unruh Channel in the context of Open Quantum Systems

abstract:
  We show through the Choi matrix approach that the effect of Unruh
acceleration on a qubit is similar to the interaction of the qubit with a
vacuum bath, despite the finiteness of the Unruh temperature. Thus, rather
counterintuitvely, from the perspective of decoherence in this framework, the
particle experiences a vacuum bath with a temperature-modified interaction
strength, rather than a thermal bath. We investigate how this "relativistic
decoherence" is modified by the presence of environmentally induced
decoherence, by studying the degradation of quantum information, as quantified
by parameters such as nonlocality, teleportation fidelity, entanglement,
coherence and quantum measurement-induced disturbance (a discord-like measure).
Also studied are the performance parameters such as gate and channel fidelity.
We highlight the distinction between dephasing and dissipative environmental
interactions, by considering the actions of quantum non-demolition and squeezed
generalized amplitude damping channels, respectively, where, in particular,
squeezing is shown to be a useful quantum resource.


title: Numerical functors on Voevodsky's motives

abstract:
  We study mixed versions of the classical quotient functor from Chow motives
to numerical motives. We compare two natural definitions, which turn out to be
very different. We investigate fullness, conservativity and exactness of these
two functors.


title:
Novel Diamond Anvil Cell for Electrical Measurements using Boron-doped
  Metallic Diamond Electrodes

abstract:
  A novel diamond anvil cell suitable for electrical transport measurements
under high pressure has been developed. A boron-doped metallic diamond film was
deposited as an electrode onto a nano-polycrystalline diamond anvil using a
microwave plasma-assisted chemical vapor deposition technique combined with
electron beam lithography. The electrical transport measurements of Pb were
performed up to 8 GPa, and the maximum pressure reached was above 30 GPa. The
boron-doped metallic diamond electrodes showed no signs of degradation after
repeated compression measurements.


title: On the role of secondary pions in spallation targets

abstract:
  We use particle-transport simulations to show that secondary pions play a
crucial role for the development of the hadronic cascade and therefore for the
production of neutrons and photons from thick spallation targets. In
particular, for the n_TOF lead spallation target, irradiated with 20 GeV/c
protons, neutral pions are involved in the production of ~90% of the
high-energy photons; charged pions participate in ~40% of the integral neutron
yield. Nevertheless, photon and neutron yields are shown to be relatively
insensitive to large changes of the average pion multiplicity in the individual
spallation reactions. We characterize this robustness as a peculiar property of
hadronic cascades in thick targets.


title: Elementary solutions of the quantum planar two center problem

abstract:
  The quantum problem of an electron moving in a plane under the field created
by two Coulombian centers admits simple analytical solutions for some
particular inter-center distances. These elementary eigenfunctions, akin to
those found by Demkov for the analogous three dimensional problem, are
calculated using the framework of quasi-exact solvability of a pair of
entangled ODE's descendants from the Heun equation. A different but interesting
situation arises when the two centers have the same strength. In this case
completely elementary solutions do not exist.


title: The micromechanics of nonlinear plastic modes

abstract:
  Nonlinear plastic modes (NPMs) are collective displacements that are
indicative of imminent plastic instabilities in elastic solids. In this work we
formulate the atomistic theory that describes the reversible evolution of NPMs
and their associated stiffnesses under external deformations. The
deformation-dynamics of NPMs is compared to those of the analogous observables
derived from atomistic linear elastic theory, namely destabilizing eigenmodes
of the dynamical matrix and their associated eigenvalues. The key result we
present and explain is that the dynamics of NPMs and of destabilizing
eigenmodes under external deformations follow different scaling laws with
respect to the proximity to imminent instabilities. In particular,
destabilizing modes vary with a singular rate, whereas NPMs' exhibit no such
singularity. As a result, NPMs converge much earlier than destabilizing
eigenmodes to their common final form at plastic instabilities. This dynamical
difference between NPMs and linear destabilizing eigenmodes underlines the
usefulness of NPMs for predicting the locus and geometry of plastic
instabilities, compared to their linear-elastic counterparts.


title:
Critical metrics of the volume functional on compact three-manifolds
  with smooth boundary

abstract:
  We study the space of smooth Riemannian structures on compact three-manifolds
with boundary that satisfies a critical point equation associated with a
boundary value problem, for simplicity, Miao-Tam critical metrics. We provide
an estimate to the area of the boundary of Miao-Tam critical metrics on compact
three-manifolds. In addition, we obtain a B\"ochner type formula which enables
us to show that a Miao-Tam critical metric on a compact three-manifold with
positive scalar curvature must be isometric to a geodesic ball in $\Bbb{S}^3.$


title:
Lyapunov exponents, sensitivity, and stability for non-autonomous
  discrete systems

abstract:
  This paper is concerned with relationships of Lyapunov exponents with
sensitivity and stability for non-autonomous discrete systems. Some new
concepts are introduced for non-autonomous discrete systems, including Lyapunov
exponents, strong sensitivity at a point and in a set, Lyapunov stability, and
exponential asymptotical stability. It is shown that the positive Lyapunov
exponent at a point implies strong sensitivity for a class of non-autonomous
discrete systems. Furthermore, the uniformly positive Lyapunov exponents in a
totally invariant set imply strong sensitivity in this set under certain
conditions. It is also shown that the negative Lyapunov exponent at a point
implies exponential asymptotical stability for a class of non-autonomous
discrete systems. The related existing results for autonomous discrete systems
are generalized to non-autonomous discrete systems and their conditions are
weaken. One example is provided for illustration.


title: R\'enyi entropy, abundance distribution and the equivalence of ensembles

abstract:
  Distributions of abundances or frequencies play an important role in many
fields of science, from biology to sociology, as does the R\'enyi entropy,
which measures the diversity of a statistical ensemble. We derive a
mathematical relation between the abundance distribution and the R\'enyi
entropy, by analogy with the equivalence of ensembles in thermodynamics. The
abundance distribution is mapped onto the density of states, and the R\'enyi
entropy to the free energy. The two quantities are related in the thermodynamic
limit by a Legendre transform, by virtue of the equivalence between the
micro-canonical and canonical ensembles. In this limit, we show how the R\'enyi
entropy can be constructed geometrically from rank-frequency plots. This
mapping predicts that non-concave regions of the rank-frequency curve should
result in kinks in the R\'enyi entropy as a function of its order. We
illustrate our results on simple examples, and emphasize the limitations of the
equivalence of ensembles when a thermodynamic limit is not well defined. Our
results help choose reliable diversity measures based on the experimental
accuracy of the abundance distributions in particular frequency ranges.


title: Counting in Practical Anonymous Dynamic Networks is Polynomial

abstract:
  Anonymous Dynamic Networks is a harsh computational environment due to
changing topology and lack of identifiers. Computing the size of the network, a
problem known as Counting, is particularly challenging because messages
received cannot be tagged to a specific sender. Previous works on Counting in
Anonymous Dynamic Networks do not provide enough guarantees to be used in
practice. Indeed, they either compute only an upper bound on the network size
that may be as bad as exponential, or guarantee only double-exponential running
time, or do not terminate, or guarantee only eventual termination without
running-time guarantees. Faster experimental protocols do not guarantee the
correct count. Recently, we presented the first Counting protocol that computes
the exact count with exponential running-time guarantees. The protocol requires
the presence of one leader node and knowledge of any upper bound Delta on the
maximum number of neighbors that any node will ever have. In the present work,
we complement the latter theoretical study evaluating the performance of such
protocol in practice. We tested a variety of network topologies that may appear
in practice, including extremal cases such as trees, paths, and continuously
changing topologies. We also tested networks that temporarily are not
connected. Our simulations showed that the protocol is polynomial for all the
inputs tested, paving the way to use it in practical applications where
topology changes are predictable. The simulations also provided insight on the
impact of topology changes on information dissemination. To the best of our
knowledge, this is the first experimental study that shows the possibility of
computing the exact count in polynomial time in a variety of Anonymous Dynamic
Networks that are worse than expected in practice.


title: Z/gamma* plus Multiple Hard Jets in High Energy Collisions

abstract:
  We present a description of the production of a di-lepton pair (through Z
boson and virtual photon) in association with at least two jets. This
calculation adds to the fixed-order accuracy the dominant logarithms in the
limit of large partonic centre-of-mass energy to all orders in the strong
coupling. This is achieved within the framework of High Energy Jets. This
calculation is made possible by extending the high energy treatment to take
into account the multiple t-channel exchanges arising from Z and
gamma*-emissions off several quark lines. The correct description of the
interference effects from the various t-channel exchanges requires an extension
of the subtraction terms in the all-order calculation. We describe this
construction and compare the resulting predictions to a number of recent
analyses of LHC data. The description of a wide range of observables is good,
and, as expected, stands out from other approaches in particular in the regions
of large dijet invariant mass and large dijet rapidity spans.


title:
Goodness of fit tests in terms of local levels with special emphasis on
  higher criticism tests

abstract:
  Instead of defining goodness of fit (GOF) tests in terms of their test
statistics, we present an alternative method by introducing the concept of
local levels, which indicate high or low local sensitivity of a test. Local
levels can act as a starting point for the construction of new GOF tests. We
study the behavior of local levels when applied to some well-known GOF tests
such as Kolmogorov-Smirnov (KS) tests, higher criticism (HC) tests and tests
based on phi-divergences. The main focus is on a rigorous characterization of
the asymptotic behavior of local levels of the original HC tests which leads to
several further asymptotic results for local levels of other GOF tests
including GOF tests with equal local levels. While local levels of KS tests,
which are related to the central range, are asymptotically strictly larger than
zero, all local levels of HC tests converge to zero as the sample size
increases. Consequently, there exists no asymptotic level $\alpha$ GOF test
such that all local levels are asymptotically bounded away from zero. Finally,
by means of numerical computations we compare classical KS and HC tests to a
GOF test with equal local levels.


title: SPREE: Spoofing Resistant GPS Receiver

abstract:
  Global Positioning System (GPS) is used ubiquitously in a wide variety of
applications ranging from navigation and tracking to modern smart grids and
communication networks. However, it has been demonstrated that modern GPS
receivers are vulnerable to signal spoofing attacks. For example, today it is
possible to change the course of a ship or force a drone to land in an hostile
area by simply spoofing GPS signals. Several countermeasures have been proposed
in the past to detect GPS spoofing attacks. These countermeasures offer
protection only against naive attackers. They are incapable of detecting strong
attackers such as those capable of seamlessly taking over a GPS receiver, which
is currently receiving legitimate satellite signals, and spoofing them to an
arbitrary location. Also, there is no hardware platform that can be used to
compare and evaluate the effectiveness of existing countermeasures in
real-world scenarios. In this work, we present SPREE, which is, to the best of
our knowledge, the first GPS receiver capable of detecting all spoofing attacks
described in literature. Our novel spoofing detection technique called
auxiliary peak tracking enables detection of even a strong attacker capable of
executing the seamless takeover attack. We implement and evaluate our receiver
against three different sets of GPS signal traces and show that SPREE
constrains even a strong attacker (capable of seamless takeover attack) from
spoofing the receiver to a location not more than 1 km away from its true
location. This is a significant improvement over modern GPS receivers that can
be spoofed to any arbitrary location. Finally, we release our implementation
and datasets to the community for further research and development.


title: Bifurcations of standing localized waves on periodic graphs

abstract:
  The nonlinear Schrodinger (NLS) equation is considered on a periodic metric
graph subject to the Kirchhoff boundary conditions. Bifurcations of standing
localized waves for frequencies lying below the bottom of the linear spectrum
of the associated stationary Schrodinger equation are considered by using
analysis of two-dimensional discrete maps near hyperbolic fixed points. We
prove existence of two distinct families of small-amplitude standing localized
waves, which are symmetric about the two symmetry points of the periodic
graphs. We also prove properties of the two families, in particular, positivity
and exponential decay. The asymptotic reduction of the two-dimensional discrete
map to the stationary NLS equation on an infinite line is discussed in the
context of the homogenization of the NLS equation on the periodic metric graph.


title: Hierarchy and Expansiveness in Two-Dimensional Subshifts of Finite Type

abstract:
  Using a deterministic version of the self-similar (or hierarchical, or
fixed-point ) method for constructing 2-dimensional subshifts of finite type
(SFTs), we construct aperiodic 2D SFTs with a unique direction of
non-expansiveness and prove that the emptiness problem of SFTs is undecidable
even in this restricted case. As an additional application of our method, we
characterize the sets of directions that can be the set of non-expansive
directions of 2D SFTs.


title: New results on mixture and exponential models by Orlicz spaces

abstract:
  New results and improvements in the study of nonparametric exponential and
mixture models are proposed. In particular, different equivalent
characterizations of maximal exponential models, in terms of open exponential
arcs and Orlicz spaces, are given. Our theoretical results are supported by
several examples and counterexamples and provide an answer to some open
questions in the literature.


title: Pulse propagation in interacting one dimensional Bose liquid

abstract:
  We study wave propagation in interacting Bose liquid, where the short range
part of the interaction between atoms is of a hard core type, and its long
range part scales with a distance as a power law. The cases of Coulomb,
dipole-dipole and Van der Waals interaction are considered. We employ a
hydrodynamic approach, based on the exact solution of Lieb-Liniger model, and
study the evolution of a density pulse instantly released from a potential
trap. We analyze semi-classical Euler and continuity equations and construct
the corresponding Riemann invariants. We supplement our analysis with numerical
calculations and discuss experimental applications for ultacold atom
experiments.


title: Ding-Iohara-Miki symmetry of network matrix models

abstract:
  Ward identities in the most general "network matrix model" can be described
in terms of the Ding-Iohara-Miki algebras (DIM). This confirms an expectation
that such algebras and their various limits/reductions are the relevant
substitutes/deformations of the Virasoro/W-algebra for (q, t) and (q_1, q_2,
q_3) deformed network matrix models. Exhaustive for these purposes should be
the Pagoda triple-affine elliptic DIM, which corresponds to networks associated
with 6d gauge theories with adjoint matter (double elliptic systems). We
provide some details on elliptic qq-characters.


title:
Double parton scattering in the ultraviolet: addressing the double
  counting problem

abstract:
  In proton-proton collisions there is a smooth transition between the regime
of double parton scattering, initiated by two pairs of partons at a large
relative distance, and the regime where a single parton splits into a parton
pair in one or both protons. We present a scheme for computing both
contributions in a consistent and practicable way.


title:
Discovery of a new extragalactic source population of energetic
  particles

abstract:
  We report the discovery of a statistically significant hardening in the
Fermi-LAT $\gamma$-ray spectrum of Centaurus A's core, with the spectral index
hardening from $\Gamma_{1}=2.73 \pm 0.02$ to $\Gamma_{1}=2.29 \pm 0.07$ at a
break energy of ($2.6 \pm 0.3$) GeV. Using a likelihood analysis, we find no
evidence for flux variability in Cen A's core lightcurve above or below the
spectral break when considering the entire 8 year period. Interestingly,
however, the first $\sim3.5$ years of the low energy lightcurve shows evidence
of flux variability at the $\sim3.5 \sigma$ confidence level. To understand the
origin of this spectral break, we assume that the low energy component below
the break feature originates from leptons in Centaurus A's radio jet and we
investigate the possibility that the high energy component above the spectral
break is due to an additional source of very high energy particles near the
core of Cen A. We show for the first time that the observed $\gamma$-ray
spectrum of an Active Galactic Nucleus is compatible with either a very large
localized enhancement (referred to as a spike) in the dark matter halo profile
or a population of millisecond pulsars. Our work constitutes the first robust
indication that new $\gamma$-ray production mechanisms can explain the emission
from active galaxies and could provide tantalizing first evidence for the
clustering of heavy dark matter particles around black holes.