title:
On the CR automorphism group of a certain hypersurface of infinite type
  in $\mathbb C^2$

abstract:
  In this article, we consider $\mathcal{C}^\infty$-smooth real hypersurfaces
of infinite type in $\mathbb C^2$. The purpose of this paper is to give
explicit descriptions for stability groups of the hypersurface
$M(a,\alpha,p,q)$ (see Sec. $1$) and a radially symmetric hypersurface in
$\mathbb C^2$.


title: Magneto-thermoelectric figure of merit of Co/Cu multilayers

abstract:
  The switching of the magnetization configurations of giant magnetoresistance
multilayer stacks not only changes the electric and thermal conductivities, but
also the thermopower. We study the magnetotransport and the
magneto-thermoelectric properties of Co/Cu multilayer devices in a lateral
thermal gradient. We derive values of the Seebeck coefficient, the
thermoelectric figure of merit, and the thermoelectric power factor. The
Seebeck coefficient reaches values up to -18 microvolt/K at room temperature
and shows a magnetic field dependence up to 28.6 % upon spin reversal. In
combination with thermal conductivity data of the same Co/Cu stack, we find a
spin dependence of the thermoelectric figure of merit of up to 65 %.
Furthermore, a spin dependence of the power factor of up to 110 % is derived.


title:
Imaging the proton concentration and mapping the spatial distribution of
  the electric field of catalytic micropumps

abstract:
  Catalytic engines can use hydrogen peroxide as a chemical fuel in order to
drive motion at the microscale. The chemo-mechanical actuation is a complex
mechanism based on the interrelation between catalytic reactions and
electro-hydrodynamics phenomena. We studied catalytic micropumps using
fluorescence confocal microscopy to image the concentration of protons in the
liquid. In addition, we measured the motion of particles with different charges
in order to map the spatial distributions of the electric field, the
electrostatic potential and the fluid flow. The combination of these two
techniques allows us to contrast the gradient of the concentration of protons
against the spatial variation in the electric field. We present numerical
simulations that reproduce the experimental results. Our work sheds light on
the interrelation between the different processes at work in the
chemo-mechanical actuation of catalytic pumps. Our experimental approach could
be used to study other electrochemical systems with heterogeneous electrodes.


title:
Gauss-Bonnet coupling constant as a free thermodynamical variable and
  the associated criticality

abstract:
  The thermodynamic phase space of Gauss-Bonnet (GB) AdS black holes is
extended, taking the inverse of the GB coupling constant as a new thermodynamic
pressure $P_{\mathrm{GB}}$. We studied the critical behavior associated with
$P_{\mathrm{GB}}$ in the extended thermodynamic phase space at fixed
cosmological constant and electric charge. The result shows that when the black
holes are neutral, the associated critical points can only exist in five
dimensional GB-AdS black holes with spherical topology, and the corresponding
critical exponents are identical to those for Van der Waals system. For charged
GB-AdS black holes, it is shown that there can be only one critical point in
five dimensions (for black holes with either spherical or hyperbolic
topologies), which also requires the electric charge to be bounded within some
appropriate range; while in $d>5$ dimensions, there can be up to two different
critical points at the same electric charge, and the phase transition can occur
only at temperatures which are not in between the two critical values.


title: Losing Weight by Gaining Edges

abstract:
  We present a new way to encode weighted sums into unweighted pairwise
constraints, obtaining the following results.
  - Define the k-SUM problem to be: given n integers in [-n^2k, n^2k] are there
k which sum to zero? (It is well known that the same problem over arbitrary
integers is equivalent to the above definition, by linear-time randomized
reductions.) We prove that this definition of k-SUM remains W[1]-hard, and is
in fact W[1]-complete: k-SUM can be reduced to f(k) * n^o(1) instances of
k-Clique.
  - The maximum node-weighted k-Clique and node-weighted k-dominating set
problems can be reduced to n^o(1) instances of the unweighted k-Clique and
k-dominating set problems, respectively. This implies a strong equivalence
between the time complexities of the node weighted problems and the unweighted
problems: any polynomial improvement on one would imply an improvement for the
other.
  - A triangle of weight 0 in a node weighted graph with m edges can be
deterministically found in m^1.41 time.


title:
Prospects for Narrow-line Cooling of KRb Molecules in Rovibrational
  Ground State

abstract:
  We propose and experimentally investigate a scheme for narrow-line cooling of
KRb molecules in the rovibrational ground state. We show that the
spin-forbidden $\mathrm{X^1\Sigma^+} \rightarrow \mathrm{b^3\Pi_{0^+}}$
transition of KRb is ideal for realizing narrow-line laser cooling of molecules
because it has highly diagonal Franck-Condon factors and narrow linewidth. In
order to confirm the prediction, we performed the optical and microwave
spectroscopy of ultracold $^{41}$K$^{87}$Rb molecules, and determined the
linewidth ($2\pi\times$ 4.9(4) kHz) and Franck-Condon factors for the
$\mathrm{X^1\Sigma^+} (v''=0) \rightarrow \mathrm{b^3\Pi_{0^+}} (v'=0)$
transition (0.9474(1)). This result opens the door towards all-optical
production of polar molecules at sub-microkelvin temperatures.


title: Discrete M\"obius Energy

abstract:
  We investigate a discrete version of the M\"obius energy, that is of
geometric interest in its own right and is defined on equilateral polygons with
$n$ segments. We show that the $\Gamma$-limit regarding $L^{q}$ or $W^{1,q}$
convergence, $q\in [1,\infty]$ of these energies as $n\to\infty$ is the smooth
M\"obius energy. This result directly implies the convergence of almost
minimizers of the discrete energies to minimizers of the smooth energy if we
can guarantee that the limit of the discrete curves belongs to the same knot
class. Additionally, we show that the unique minimizer amongst all polygons is
the regular $n$-gon. Moreover, discrete overall minimizers converge to the
round circle.


title:
Phase Noise of the Radio Frequency (RF) Beatnote Generated by a
  Dual-Frequency VECSEL

abstract:
  We analyze, both theoretically and experimentally, the phase noise of the
radio frequency (RF) beatnote generated by optical mixing of two orthogonally
polarized modes in an optically pumped dual-frequency Vertical External Cavity
Surface Emitting Laser (VECSEL). The characteristics of the RF phase noise
within the frequency range of 10 kHz - 50 MHz are investigated for three
different nonlinear coupling strengths between the two lasing modes. In the
theoretical model, we consider two different physical mechanisms responsible
for the RF phase noise. In the low frequency domain (typically below 500 kHz),
the dominant contribution to the RF phase noise is shown to come from the
thermal fluctuations of the semicondutor active medium induced by pump
intensity fluctuations. However, in the higher frequency domain (typically
above 500 kHz), the main source of RF phase noise is shown to be the pump
intensity fluctuations which are transfered to the intensity noises of the two
lasing modes and then to the phase noise via the large Henry factor of the
semiconductor gain medium. For this latter mechanism, the nonlinear coupling
strength between the two lasing modes is shown to play an important role in the
value of the RF phase noise. All experimental results are shown to be in good
agreement with theory.


title: On special partial types and weak canonical bases in simple theories

abstract:
  We define a notion of a weak canonical base for a partial type. This notion
is weaker than the usual canonical base for an amalgamation base. We prove that
certain family of partial types have a weak canonical base. This family clearly
contains the class of amalgamation bases.


title: Inelastic neutron scattering study of phonon anomalies in La1.5Sr0.5NiO4

abstract:
  The high-energy phonons in La1.5Sr0.5NiO4, in which the checkerboard charge
ordering is formed, was investigated by the inelastic neutron scattering. We
found that the longitudinal modes show strong anomalies compared with La2NiO4.
We argue the similarity and difference in the phonon anomalies between the
present sample and the preceding works of different compositions.


title:
Extreme value copula estimation based on block maxima of a multivariate
  stationary time series

abstract:
  The core of the classical block maxima method consists of fitting an extreme
value distribution to a sample of maxima over blocks extracted from an
underlying series. In asymptotic theory, it is usually postulated that the
block maxima are an independent random sample of an extreme value distribution.
In practice however, block sizes are finite, so that the extreme value
postulate will only hold approximately. A more accurate asymptotic framework is
that of a triangular array of block maxima, the block size depending on the
size of the underlying sample in such a way that both the block size and the
number of blocks within that sample tend to infinity. The copula of the vector
of componentwise maxima in a block is assumed to converge to a limit, which,
under mild conditions, is then necessarily an extreme value copula. Under this
setting and for absolutely regular stationary sequences, the empirical copula
of the sample of vectors of block maxima is shown to be a consistent and
asymptotically normal estimator for the limiting extreme value copula.
Moreover, the empirical copula serves as a basis for rank-based, nonparametric
estimation of the Pickands dependence function of the extreme value copula. The
results are illustrated by theoretical examples and a Monte Carlo simulation
study.


title:
Weak ergodicity breaking in an anomalous diffusion process of mixed
  origins

abstract:
  The ergodicity breaking parameter is a measure for the heterogeneity among
different trajectories of one ensemble. In this report this parameter is
calculated for fractional Brownian motion with a random change of time scale,
often called "subordination". We proceed to show that this quantity is the same
as the known CTRW case.


title: Ants: Mobile Finite State Machines

abstract:
  Consider the Ants Nearby Treasure Search (ANTS) problem introduced by
Feinerman, Korman, Lotker, and Sereni (PODC 2012), where $n$ mobile agents,
initially placed at the origin of an infinite grid, collaboratively search for
an adversarially hidden treasure. In this paper, the model of Feinerman et al.
is adapted such that the agents are controlled by a (randomized) finite state
machine: they possess a constant-size memory and are able to communicate with
each other through constant-size messages. Despite the restriction to
constant-size memory, we show that their collaborative performance remains the
same by presenting a distributed algorithm that matches a lower bound
established by Feinerman et al. on the run-time of any ANTS algorithm.


title: Convergent perturbative nuclear effective field theory

abstract:
  We consider the nuclear effective field theory including pions in the
two-nucleon sector in the S waves up to including the next-to-next-to-leading
order (NNLO) terms according to the power counting suggested by the Wilsonian
renormalization group analysis done in a previous paper. We treat only the
leading contact interaction nonperturbatively, and the rest, including the
long-distance part of pion exchange, are treated as perturbations. To define
the long-distance part, it is important to introduce a separation scale, or a
cutoff. We employ a hybrid regularization, in which the loops with only contact
interactions are regularized with Power Divergence Subtraction (PDS), while the
loops with (long-distance part of) pion exchange are regularized with a
Gaussian damping factor (GDF), to simplify the (nonperturbative) leading-order
amplitudes. The scale introduced by PDS is identified with the cutoff of GDF up
to a numerical factor. We emphasize that the introduction of the GDF requires a
careful definition of the coupling constant for the pion exchange. We obtain
the analytic expressions for the phase shifts for the $^1S_0$ and
$^3S_1$-$^3D_1$ channels. By fitting them to the Nijmegen partial wave analysis
data, it is shown that the effective theory expansion with perturbative
long-distance part of pion exchange is converging.


title: Ranking users, papers and authors in online scientific communities

abstract:
  The ever-increasing quantity and complexity of scientific production have
made it difficult for researchers to keep track of advances in their own
fields. This, together with growing popularity of online scientific
communities, calls for the development of effective information filtering
tools. We propose here a method to simultaneously compute reputation of users
and quality of scientific artifacts in an online scientific community.
Evaluation on artificially-generated data and real data from the Econophysics
Forum is used to determine the method's best-performing variants. We show that
when the method is extended by considering author credit, its performance
improves on multiple levels. In particular, top papers have higher citation
count and top authors have higher $h$-index than top papers and top authors
chosen by other algorithms.


title:
Spin current source based on a quantum point contact with local
  spin-orbit interaction

abstract:
  Proposal for construction of a source of spin-polarized current based on
quantum point contact with local spin-orbit interaction is presented. We show
that spin-orbit interaction present within the narrowing acts like a spin
filter. The spin polarization of the current is discussed as a function of the
Fermi energy and the width of the quantum point contact.


title:
On the effect of perturbation of conditional probabilities in total
  variation

abstract:
  A celebrated result by A. Ionescu Tulcea provides a construction of a
probability measure on a product space given a sequence of regular conditional
probabilities. We study how the perturbations of the latter in the total
variation metric affect the resulting product probability measure.


title:
Exchange bias up to room temperature in the antiferromagnetic bulk
  hexagonal Mn3Ge

abstract:
  This work reports an exchange bias (EB) effect up to room temperature in the
binary intermetallic bulk compound Mn3.04Ge0.96. The sample annealed at 700 K
crystallizes in a tetragonal structure with ferromagnetic ordering, whereas,
the sample annealed at 1073 K crystallizes in a hexagonal structure with
antiferromagnetic ordering. The hexagonal Mn3.04Ge0.96 sample exhibits an EB of
around 70 mT at 2 K that continues with a non-zero value up to room
temperature. The exchange anisotropy is proposed to be originating from the
exchange interaction between the triangular antiferromagnetic host and the
embedded ferrimagnetic like clusters. The ferrimagnetic clusters develop when
excess Mn atoms occupy empty Ge sites in the original triangular
antiferromagnet structure of Mn3Ge.


title:
Distinguishing electronic and vibronic coherence in 2D spectra by their
  temperature dependence

abstract:
  Long-lived oscillations in 2D spectra of chlorophylls are at the heart of an
ongoing debate. Their physical origin is either a multi-pigment effect, such as
excitonic coherence, or primarily stems from localized vibrations. In the
present work, we analyze distinguishing characteristics of relative phase
difference measured between diagonal- and cross-peak oscillations. While direct
discrimination between the two scenarios is obscured when peaks overlap, their
sensitivity to temperature provides a stronger argument. We show that
vibrational (vibronic) oscillations change relative phase with temperature,
while electronic oscillations are only weakly dependent. This highlights that
studies of relative phase difference as a function of temperature provide a
clear and easily accessible method to distinguish between vibrational and
electronic coherences.


title:
Non-Markovian Reduced Systems for Stochastic Partial Differential
  Equations: The Additive Noise Case

abstract:
  This article proposes for stochastic partial differential equations (SPDEs)
driven by additive noise, a novel approach for the approximate
parameterizations of the ``small'' scales by the ``large'' ones, along with the
derivaton of the corresponding reduced systems. This is accomplished by seeking
for stochastic parameterizing manifolds (PMs) introduced in a previous work by
the authors(*), which are random manifolds aiming to provide --- in a mean
square sense --- such approximate parameterizations. Backward-forward systems
are designed to give access to such PMs as pullback limits depending through
the nonlinear terms on the time-history of the dynamics of the low modes when
the latter is simply approximated by its stochastic linear component. It is
shown that the corresponding pullback limits can be efficiently determined,
leading in turn to an operational procedure for the derivation of non-Markovian
reduced systems able to achieve good modeling performances in practice. This is
illustrated on a stochastic Burgers-type equation, where it is shown that the
corresponding non-Markovian features of these reduced systems play a key role
to reach such performances.


title:
The Distributed Computing Paradigms: P2P, Grid, Cluster, Cloud, and
  Jungle

abstract:
  The distributed computing is done on many systems to solve a large scale
problem. The growing of high-speed broadband networks in developed and
developing countries, the continual increase in computing power, and the rapid
growth of the Internet have changed the way. In it the society manages
information and information services. Historically, the state of computing has
gone through a series of platform and environmental changes. Distributed
computing holds great assurance for using computer systems effectively. As a
result, supercomputer sites and data centers have changed from providing high
performance floating point computing capabilities to concurrently servicing
huge number of requests from billions of users. The distributed computing
system uses multiple computers to solve large-scale problems over the Internet.
It becomes data-intensive and network-centric. The applications of distributed
computing have become increasingly wide-spread. In distributed computing, the
main stress is on the large scale resource sharing and always goes for the best
performance. In this article, we have reviewed the work done in the area of
distributed computing paradigms. The main stress is on the evolving area of
cloud computing.


title: Java File Security System (JFSS)

abstract:
  Nowadays, storage systems are increasingly subject to attacks. So the
security system is quickly becoming mendatory feature of the data storage
systems. For the security purpose we are always dependent on the cryptography
techniques. These techniques take the performance costs for the complete
system. So we have proposed the Java File Security System(JFSS). It is based on
the on-demand computing system concept, because of the performance issues. It
is a greate comback for the system performance. The concept is used because, we
are not always in need the secure the files, but the selected one only. In this
paper, we have designed a file security system on Windows XP. When we use the
operating system, we have to secure some important data. The date is always
stored in the files, so we secure the important files well. To check the
proposed functionality, we experiment the above said system on the Windows
operating system. With these experiments, we have found that the proposed
system is working properly, according to the needs of the users.


title:
Non-degenerate homogeneous $\epsilon$-K\"ahler and $\epsilon$-quaternion
  K\"ahler structures of linear type

abstract:
  We study the class of non-degenerate homogeneous structures of linear type in
the pseudo-K\"ahler, para-K\"ahler, pseudo-quaternion K\"ahler and
para-quaternion K\"ahler cases. We show that these structures characterize
spaces of constant holomorphic, para-holomorphic, quaternion and
para-quaternion sectional curvature respectively. In addition the corresponding
homogeneous models are computed, exhibiting the relation between these kind of
structures and the incompleteness of the metric.


title:
Correctors for the Neumann problem in thin domains with locally periodic
  oscillatory structure

abstract:
  In this paper we are concerned with convergence of solutions of the Poisson
equation with Neumann boundary conditions in a two-dimensional thin domain
exhibiting highly oscillatory behavior in part of its boundary. We deal with
the resonant case in which the height, amplitude and period of the oscillations
are all of the same order which is given by a small parameter $\epsilon > 0$.
Applying an appropriate corrector approach we get strong convergence when we
replace the original solutions by a kind of first-order expansion through the
Multiple-Scale Method.


title: The weak choice principle WISC may fail in the category of sets

abstract:
  The set-theoretic axiom WISC states that for every set there is a set of
surjections to it cofinal in all such surjections. By constructing an unbounded
topos over the category of sets and using an extension of the internal logic of
a topos due to Shulman, we show that WISC is independent of the rest of the
axioms of the set theory given by a well-pointed topos. This also gives an
example of a topos that is not a predicative topos as defined by van den Berg.


title:
The story of Seyfert galaxy RE J2248-511: from intriguingly ultrasoft to
  unremarkably average

abstract:
  RE J2248-511 is one of only 14 non-blazar AGN detected in the far ultraviolet
by the ROSAT Wide Field Camera implying a large ultrasoft X-ray flux. This soft
X-ray excess is strongly variable on year timescales, a common property of
Narrow Line Seyfert 1s, yet its optical linewidths classify this source as a
broad-lined Seyfert 1. We use four nearly simultaneous optical--X-ray SEDs
spanning 7 years to study the spectral shape and long term variability of RE
J2248-511.
  Here we show that the continuum SED for the brightest epoch dataset is
consistent with the mean SED of a standard quasar, and matches well to that
from an XMM-SDSS sample of AGN with <M/M_Sun> ~ 10^8 and <L/L_Edd> ~ 0.2. All
the correlated optical and soft X-ray variability can be due entirely to a
major absorption event. The only remarkable aspect of this AGN is that there is
no measurable intrinsic X-ray absorption column in the brightest epoch dataset.
The observed FUV flux is determined by the combination of this and the fact
that the source lies within a local absorption `hole'. RE J2248-511, whose
variable, ultrasoft X-ray flux once challenged its BLS1 classification,
demonstrates that characterisation of such objects requires multi-epoch,
multi-wavelength campaigns.


title:
An Efficient Method for Recognizing the Low Quality Fingerprint
  Verification by Means of Cross Correlation

abstract:
  In this paper, we propose an efficient method to provide personal
identification using fingerprint to get better accuracy even in noisy
condition. The fingerprint matching based on the number of corresponding
minutia pairings, has been in use for a long time, which is not very efficient
for recognizing the low quality fingerprints. To overcome this problem,
correlation technique is used. The correlation-based fingerprint verification
system is capable of dealing with low quality images from which no minutiae can
be extracted reliably and with fingerprints that suffer from non-uniform shape
distortions, also in case of damaged and partial images. Orientation Field
Methodology (OFM) has been used as a preprocessing module, and it converts the
images into a field pattern based on the direction of the ridges, loops and
bifurcations in the image of a fingerprint. The input image is then Cross
Correlated (CC) with all the images in the cluster and the highest correlated
image is taken as the output. The result gives a good recognition rate, as the
proposed scheme uses Cross Correlation of Field Orientation (CCFO = OFM + CC)
for fingerprint identification.


title: Liouville theorem for Pseudoharmonic maps from Sasakian manifolds

abstract:
  In this paper, we derive a sub-gradient estimate for pseudoharmonic maps from
noncompact complete Sasakian manifolds which satisfy CR sub-Laplace comparison
property, to simply-connected Riemannian manifolds with nonpositive sectional
curvature. As its application, we obtain some Liouville theorems for
pseudoharmonic maps. In the Appendix, we modify the method and apply it to
harmonic maps from noncompact complete Sasakian manifolds.


title: Smart: Semantically mashup rest web services

abstract:
  A mashup is a combination of information from more than one source, mixed up
in a way to create something new, or at least useful. Anyone can find mashups
on the internet, but these are always specifically designed for a predefined
purpose. To change that fact, we implemented a new platform we called the SMART
platform. SMART enables the user to make his own choices as for the REST web
services he needs to call in order to build an intelligent personalized mashup,
from a Google-like simple search interface, without needing any programming
skills. In order to achieve this goal, we defined an ontology that can hold
REST web services descriptions. These descriptions encapsulate mainly, the
input type needed for a service, its output type, and the kind of relation that
ties the input to the output. Then, by matching the user input query keywords,
with the REST web services definitions in our ontology, we can find registered
services individuals in this ontology, and construct the raw REST query for
each service found. The wrap up from the keywords, into semantic definitions,
in order to find the matching service individual, then the wrap down from the
semantic service description of the found individual, to the raw REST call, and
finally the wrap up of the result again into semantic individuals, is done for
two main purposes: the first to let the user use simple keywords in order to
build complex mashups, and the second to benefit from the ontology inference
engine in a way, where services instances can be tied together into an
intelligent mashup, simply by making each service output individuals, stand as
the next service input.


title: A Modica-Mortola approximation for the Steiner Problem

abstract:
  In this note we present a way to approximate the Steiner problem by a family
of elliptic energies of Modica-Mortola type, with an additional term relying on
the weighted geodesic distance which takes care of the connexity constraint.


title:
Pseudoscalar decay constants $f_K/f_\pi$, $f_D$ and $f_{D_s}$ with $N_f
  = 2 + 1 + 1$ ETMC configurations

abstract:
  We present a lattice QCD calculation of the pseudoscalar decay constants
$f_K$, $f_D$ and $f_{D_s}$ performed by the European Twisted Mass Collaboration
with $N_f = 2 + 1 + 1$ dynamical fermions. We simulated at three different
values of the lattice spacing, the smallest being approximately $0.06fm$, and
with pion masses as small as $210$MeV. Our main results are:
$f_{K^+}/f_{\pi^+}=1.183(17)$, $f_{K^+}=154.4(2.1)$MeV,
$f_{D_s}=242.1(8.3)$MeV, $f_D=201.9(8.0)$MeV, $f_{D_s}/f_D=1.199(25)$ and
$(f_{D_s}/f_D) / (f_K/f_\pi) = 1.005(15)$.


title: Chiral behaviour of the pion decay constant in $N_f=2$ QCD

abstract:
  As increased statistics and new ensembles with light pions have become
available within the CLS effort, we complete previous work by inspecting the
chiral behaviour of the pion decay constant. We discuss the validity of Chiral
Perturbation Theory ($\chi$PT) and examine the results concerning the pion
decay constant and the ensuing scale setting, the pion mass squared in units of
the quark mass, and the ratio of decay constants $f_K/f_\pi$; along the way,
the relevant low-energy constants of SU(2) $\chi$PT are estimated. All
simulations were performed with two dynamical flavours of nonperturbatively
O(a)-improved Wilson fermions, on volumes with $m_\pi L \geq 4$, pion masses
$\geq$ 192 MeV and lattice spacings down to 0.048 fm. Our error analysis takes
into account the effect of slow modes on the autocorrelations.


title: Another Proof of Segre's Theorem about Ovals

abstract:
  In 1955 B. Segre showed that any oval in a projective plane over a finite
field of odd order is a conic. His proof constructs a conic which matches the
oval in some points, and then shows that it actually coincides with the oval.
Here we give another proof. We describe the oval by a possibly high degree
polynomial, and then show that the degree is actually 2.


title:
Anharmonic free energies and phonon dispersions from the stochastic
  self-consistent harmonic approximation: application to platinum and palladium
  hydrides

abstract:
  Harmonic calculations based on density-functional theory are generally the
method of choice for the description of phonon spectra of metals and
insulators. The inclusion of anharmonic effects is, however, delicate as it
relies on perturbation theory requiring a considerable amount of computer time,
fast increasing with the cell size. Furthermore, perturbation theory breaks
down when the harmonic solution is dynamically unstable or the anharmonic
correction of the phonon energies is larger than the harmonic frequencies
themselves.We present a stochastic implementation of the self-consistent
harmonic approximation valid to treat anharmonicity at any temperature in the
non-perturbative regime. The method is based on the minimization of the free
energy with respect to a trial density matrix described by an arbitrary
harmonic Hamiltonian. The minimization is performed with respect to all the
free parameters in the trial harmonic Hamiltonian, namely, equilibrium
positions, phonon frequencies and polarization vectors. The gradient of the
free energy is calculated following a stochastic procedure. The method can be
used to calculate thermodynamic properties, dynamical properties and anharmonic
corrections to the Eliashberg function of the electron-phonon coupling. The
scaling with the system size is greatly improved with respect to perturbation
theory. The validity of the method is demonstrated in the strongly anharmonic
palladium and platinum hydrides. In both cases we predict a strong anharmonic
correction to the harmonic phonon spectra, far beyond the perturbative limit.
In palladium hydrides we calculate thermodynamic properties beyond the
quasiharmonic approximation, while in PtH we demonstrate that the high
superconducting critical temperatures at 100 GPa predicted in previous
calculations based on the harmonic approximation are strongly suppressed when
anharmonic effects are included.


title:
On the iterated Stieltjes transform and its convolution with
  applications to singular integral equations

abstract:
  We consider mapping properties of the iterated Stieltjes transform,
establishing its new relations with the iterated Hilbert transform (a singular
integral) on the half-axis and proving the corresponding convolution and
Titchmarsh's type theorems. Moreover, the obtained convolution method is
applied to solve a new class of singular integral equations.


title: Community detection thresholds and the weak Ramanujan property

abstract:
  Decelle et al.\cite{Decelle11} conjectured the existence of a sharp threshold
for community detection in sparse random graphs drawn from the stochastic block
model. Mossel et al.\cite{Mossel12} established the negative part of the
conjecture, proving impossibility of meaningful detection below the threshold.
However the positive part of the conjecture remained elusive so far. Here we
solve the positive part of the conjecture. We introduce a modified adjacency
matrix $B$ that counts self-avoiding paths of a given length $\ell$ between
pairs of nodes and prove that for logarithmic $\ell$, the leading eigenvectors
of this modified matrix provide non-trivial detection, thereby settling the
conjecture. A key step in the proof consists in establishing a {\em weak
Ramanujan property} of matrix $B$. Namely, the spectrum of $B$ consists in two
leading eigenvalues $\rho(B)$, $\lambda_2$ and $n-2$ eigenvalues of a lower
order $O(n^{\epsilon}\sqrt{\rho(B)})$ for all $\epsilon>0$, $\rho(B)$ denoting
$B$'s spectral radius. $d$-regular graphs are Ramanujan when their second
eigenvalue verifies $|\lambda|\le 2 \sqrt{d-1}$. Random $d$-regular graphs have
a second largest eigenvalue $\lambda$ of $2\sqrt{d-1}+o(1)$ (see
Friedman\cite{friedman08}), thus being {\em almost} Ramanujan.
Erd\H{o}s-R\'enyi graphs with average degree $d$ at least logarithmic
($d=\Omega(\log n)$) have a second eigenvalue of $O(\sqrt{d})$ (see Feige and
Ofek\cite{Feige05}), a slightly weaker version of the Ramanujan property.
However this spectrum separation property fails for sparse ($d=O(1)$)
Erd\H{o}s-R\'enyi graphs. Our result thus shows that by constructing matrix $B$
through neighborhood expansion, we regularize the original adjacency matrix to
eventually recover a weak form of the Ramanujan property.


title: A smaller counterexample to the Lando conjecture

abstract:
  The following conjecture was proposed in 2010 by S. Lando. Let M and N be two
unions of the same number of disjoint circles in a sphere. Then there exist two
spheres in 3-space whose intersection is transversal and is a union of disjoint
circles that is situated as M in one sphere and as N in the other . Define
union A of disjoint circles to be situated in one sphere as union B of disjoint
circles in the other sphere if there is a homeomorphism between these two
spheres which maps A to B.
  In this paper we prove that there exists pair of sets of 7 circles in sphere,
that is a counterexample to the Lando conjecture. This is proved using the
Avvakumov Theorem. We conjecture that there exists no pair (M,N) that is
counterexample and M contains 6 or less circles.


title:
A Fractal and Scale-free Model of Complex Networks with Hub Attraction
  Behaviors

abstract:
  It is widely believed that fractality of complex networks origins from hub
repulsion behaviors (anticorrelation or disassortativity), which means large
degree nodes tend to connect with small degree nodes. This hypothesis was
demonstrated by a dynamical growth model, which evolves as the inverse
renormalization procedure proposed by Song et al. Now we find that the
dynamical growth model is based on the assumption that all the cross-boxes
links has the same probability e to link to the most connected nodes inside
each box. Therefore, we modify the growth model by adopting the flexible
probability e, which makes hubs have higher probability to connect with hubs
than non-hubs. With this model, we find some fractal and scale-free networks
have hub attraction behaviors (correlation or assortativity). The results are
the counter-examples of former beliefs.


title:
Endogenous games with goals: side-payments among goal-directed
  artificial agents

abstract:
  Artificial agents are typically oriented to the realization of an externally
assigned task and try to optimize over secondary aspects of plan execution such
time lapse or power consumption, technically displaying a quasi-dichotomous
preference relation. Boolean games have been developed as a paradigm for
modelling societies of agents with this type of preference. In boolean games
agents exercise control over propositional variables and strive to achieve a
goal formula whose realization might require the opponents' cooperation.
Recently, a theory of incentive engineering for such games has been devised,
where an external authority steers the outcome of the game towards certain
desirable properties consistent with players' goals, by imposing a taxation
mechanism on the players that makes the outcomes that do not comply with those
properties less appealing to them. The present contribution stems from a
complementary perspective and studies, instead, how games with
quasi-dichotomous preferences can be transformed from inside, rather than from
outside, by endowing players with the possibility of sacrificing a part of
their payoff received at a certain outcome in order to convince other players
to play a certain strategy. Concretely we explore the properties of endogenous
games with goals, obtained coupling strategic games with goals, a
generalization of boolean games, with the machinery of endogenous games coming
from game theory. We analyze equilibria in those structures, showing the
preconditions needed for desirable outcomes to be achieved without external
intervention. What our results show is that endogenous games with goals display
specific irreducible features - with respect to what already known for
endogenous games - which makes them worth studying in their own sake.


title:
Distinguishing the effects of internal and forced atmospheric
  variability in climate networks

abstract:
  The fact that the Earth climate is a highly complex dynamical system is
well-known. In the last few decades a lot of effort has been focused on
understanding how climate phenomena in one geographical region affects the
climate of other regions. Complex networks are a powerful framework for
identifying climate interdependencies. To further exploit the knowledge of the
links uncovered via the network analysis (for, e.g., improvements in
prediction), a good understanding of the physical mechanisms underlying these
links is required. Here we focus in understanding the role of atmospheric
variability, and construct climate networks representing internal and forced
variability. In the connectivity of these networks we assess the influence of
two main indices, NINO3.4 and the North Atlantic Oscillation (NAO), by
calculating the networks from time-series where these indices were linearly
removed. We find that the connectivity of the forced variability network is
heavily affected by ``El Ni\~no'': removing the NINO3.4 index yields a general
loss of connectivity; even teleconnections between regions far away from the
equatorial Pacific ocean are lost, suggesting that these regions are not
directly linked, but rather, are indirectly interconnected via ``El Ni\~no'',
particularly on interannual time scales. On the contrary, in the internal
variability network (independent of sea surface temperature forcing) we find
that the links are significantly affected by NAO with a maximum in intra-annual
time scales. While the strongest non-local links found are those forced by the
ocean, we show that there are also strong teleconnections due to internal
atmospheric variability.


title: Modulated Inflation Models and Primordial Black Holes

abstract:
  For the first time, the running of the running of the spectral index
$\beta_s$ has been measured by Planck. This parameter is crucial for dark
matter Primordial Black Holes (PBHs) formation. We study the PBHs formation in
inflation potentials with superimposed periodic oscillations. We show that the
value of $\beta_s$ suggested by the recent cosmic microwave background data is
easily explained in these models. As a by-product, we also show that the
nonproduction of (long--lived) PBHs puts a stronger upper bound on $\beta_s$.


title: 3XMM J185246.6+003317: another low magnetic field magnetar

abstract:
  We study the outburst of the newly discovered X-ray transient 3XMM
J185246.6+003317, re-analysing all available XMM-Newton, observations of the
source to perform a phase-coherent timing analysis, and derive updated values
of the period and period derivative. We find the source rotating at
P=11.55871346(6) s (90% confidence level; at epoch MJD 54728.7) but no evidence
for a period derivative in the 7 months of outburst decay spanned by the
observations. This translates in a 3sigma upper limit for the period derivative
of Pdot<1.4x10^{-13} s/s, which, assuming the classical magneto-dipolar braking
model, gives a limit on the dipolar magnetic field of B_dip<4.1x10^{13} G . The
X-ray outburst and spectral characteristics of 3XMM J185246.6+003317 confirms
the identification as a magnetar, but the magnetic field upper limit we derive
defines it as the third "low-B" magnetar discovered in the past three years,
after SGR 0418+5729 and Swift J1822.3-1606. We have also obtained an upper
limit to the quiescent luminosity (< 4x10^{33} erg/s), in line with the
expectations for an old magnetar. The discovery of this new low field magnetar
reaffirms the prediction of about one outburst per year from the hidden
population of aged magnetars.


title:
Posterior consistency for nonparametric hidden Markov models with finite
  state space

abstract:
  In this paper we study posterior consistency for different topologies on the
parameters for hidden Markov models with finite state space. We first obtain
weak and strong posterior consistency for the marginal density function of
finitely many consecutive observations. We deduce posterior consistency for the
different components of the parameter. We also obtain posterior consistency for
marginal smoothing distributions in the discrete case. We finally apply our
results to independent emission probabilities, translated emission
probabilities and discrete HMMs, under various types of priors.


title:
Disc-loss episode in the Be shell optical counterpart to the high-mass
  X-ray binary IGR J21343+4738

abstract:
  The main goal of this work is to determine the properties of the optical
counterpart to the INTEGRAL source IGR J21343+4738, and study its long-term
optical variability. We present optical photometric BVRI and spectroscopic
observations covering the wavelength band 4000-7500 A. We find that the optical
counterpart to IGR J21343+4738 is a V=14.1 B1IVe shell star located at a
distance of ~8.5 kpc. The Halpha line changed from an absorption dominated
profile to an emission dominated profile, and then back again into absorption.
In addition, fast V/R asymmetries were observed once the disc developed.
Although the Balmer lines are the most strongly affected by shell absorption,
we find that shell characteristics are also observed in He I lines. The optical
spectral variability of IGR J21343+4738 is attributed to the formation of an
equatorial disc around the Be star and the development of an enhanced density
perturbation that revolves inside the disc. We have witnessed the formation and
dissipation of the circumstellar disc. The strong shell profile of the Halpha
and He I lines and the fact that no transition from shell phase to a pure
emission phase is seen imply that we are seeing the system near edge-on.


title: Hadronic freeze-out in an effective relativistic mean field model

abstract:
  We investigate an effective relativistic equation of state at finite values
of temperature and baryon chemical potential with the inclusion of the full
octet of baryons, the Delta-isobars and the lightest pseudoscalar and vector
meson degrees of freedom. These last particles have been introduced within a
phenomenological approach by taking into account of an effective chemical
potential and mass depending on the self-consistent interaction between
baryons. In this framework, we study of the hadron yield ratios measured in
central heavy ion collisions over a broad energy range and present the beam
energy dependence of underlying dynamic quantities like the net baryon density
and the energy density.


title:
Collisionless microinstabilities in stellarators I - analytical theory
  of trapped-particle modes

abstract:
  This is the first of two papers about collisionless, electrostatic
micro-instabilities in stellarators, with an emphasis on trapped-particle
modes. It is found that, in so-called maximum-$J$ configurations,
trapped-particle instabilities are absent in large regions of parameter space.
Quasi-isodynamic stellarators have this property (approximately), and the
theory predicts that trapped electrons are stabilizing to all eigenmodes with
frequencies below the electron bounce frequency. The physical reason is that
the bounce-averaged curvature is favorable for all orbits, and that trapped
electrons precess in the direction opposite to that in which drift waves
propagate, thus precluding wave-particle resonance. These considerations only
depend on the electrostatic energy balance, and are independent of all
geometric properties of the magnetic field other than the maximum-$J$
condition. However, if the aspect ratio is large and the instability phase
velocity differs greatly from the electron and ion thermal speeds, it is
possible to derive a variational form for the frequency showing that stability
prevails in a yet larger part of parameter space than what follows from the
energy argument. Collisionless trapped-electron modes should therefore be more
stable in quasi-isodynamic stellarators than in tokamaks.


title: A lower bound of the least signless Laplacian eigenvalue of a graph

abstract:
  Let $G$ be a simple connected graph on $n$ vertices and $m$ edges. In [Linear
Algebra Appl. 435 (2011) 2570-2584], Lima et al. posed the following conjecture
on the least eigenvalue $q_n(G)$ of the signless Laplacian of $G$:
$\displaystyle q_n(G)\ge {2m}/{(n-1)}-n+2$. In this paper we prove a stronger
result: For any graph with $n$ vertices and $m$ edges, we have $\displaystyle
q_n(G)\ge {2m}/{(n-2)}-n+1 (n\ge 6)$.


title:
Functional Mn--Mg$_k$ cation complexes in GaN featured by Raman
  spectroscopy

abstract:
  The evolution of the optical branch in the Raman spectra of (Ga,Mn)N:Mg
epitaxial layers as a function of the Mn and Mg concentrations, reveals the
interplay between the two dopants. We demonstrate that the various
Mn-Mg-induced vibrational modes can be understood in the picture of functional
Mn--Mg$_k$ complexes formed when substitutional Mn cations are bound to $k$
substitutional Mg through nitrogen atoms, the number of ligands $k$ being
driven by the ratio between the Mg and the Mn concentrations.


title: Existence of flips and minimal models for 3-folds in char p

abstract:
  We will prove the following results for $3$-fold pairs $(X,B)$ over an
algebraically closed field $k$ of characteristic $p>5$: log flips exist for
$\Q$-factorial dlt pairs $(X,B)$; log minimal models exist for projective klt
pairs $(X,B)$ with pseudo-effective $K_X+B$; the log canonical ring $R(K_X+B)$
is finitely generated for projective klt pairs $(X,B)$ when $K_X+B$ is a big
$\Q$-divisor; semi-ampleness holds for a nef and big $\Q$-divisor $D$ if
$D-(K_X+B)$ is nef and big and $(X,B)$ is projective klt; $\Q$-factorial dlt
models exist for lc pairs $(X,B)$; terminal models exist for klt pairs $(X,B)$;
ACC holds for lc thresholds; etc.


title:
Cryptanalysis of An Advanced Temporal Credential-Based Security Scheme
  with Mutual Authentication and Key Agreement for Wireless Sensor Networks

abstract:
  With the rapid advancement of wireless network technology, usage of WSN in
real time applications like military, forest monitoring etc. found increasing.
Generally WSN operate in an unattended environment and handles critical data.
Authenticating the user trying to access the sensor memory is one of the
critical requirements. Many researchers have proposed remote user
authentication schemes focusing on various parameters. In 2013, Li et al.
proposed a temporal-credential-based mutual authentication and key agreement
scheme for WSNs. Li et al. claimed that their scheme is secure against all
major cryptographic attacks and requires less computation cost due to usage of
hash function instead encryption operations. Unfortunately, in this paper we
will show that their scheme is vulnerable to offline password guessing attack,
stolen smart card attack, leakage of password etc. and failure to provide data
privacy.


title:
Controlling the coherence in a pure dephasing model for an arbitrarily
  prescribed time span

abstract:
  We present an open-loop unitary strategy to control the coherence in a pure
dephasing model (related to the phase-flip channel) that is able to recover,
for whatever prescribed time span, the initial coherence at the end of the
control process. The strategy's key idea is to steer the quantum state to the
subset of invariant states and keep it there the necessary time, using a fine
tuned control Hamiltonian.


title: Possible climates on terrestrial exoplanets

abstract:
  What kind of environment may exist on terrestrial planets around other stars?
In spite of the lack of direct observations, it may not be premature to
speculate on exoplanetary climates, for instance to optimize future telescopic
observations, or to assess the probability of habitable worlds. To first order,
climate primarily depends on 1) The atmospheric composition and the volatile
inventory; 2) The incident stellar flux; 3) The tidal evolution of the
planetary spin, which can notably lock a planet with a permanent night side.
The atmospheric composition and mass depends on complex processes which are
difficult to model: origins of volatile, atmospheric escape, geochemistry,
photochemistry. We discuss physical constraints which can help us to speculate
on the possible type of atmosphere, depending on the planet size, its final
distance for its star and the star type. Assuming that the atmosphere is known,
the possible climates can be explored using Global Climate Models analogous to
the ones developed to simulate the Earth as well as the other telluric
atmospheres in the solar system. Our experience with Mars, Titan and Venus
suggests that realistic climate simulators can be developed by combining
components like a "dynamical core", a radiative transfer solver, a
parametrisation of subgrid-scale turbulence and convection, a thermal ground
model, and a volatile phase change code. On this basis, we can aspire to build
reliable climate predictors for exoplanets. However, whatever the accuracy of
the models, predicting the actual climate regime on a specific planet will
remain challenging because climate systems are affected by strong positive
destabilizing feedbacks (such as runaway glaciations and runaway greenhouse
effect). They can drive planets with very similar forcing and volatile
inventory to completely different states.


title:
Matter-wave solitons supported by field-induced dipole-dipole repulsion
  with a spatially modulated strength

abstract:
  We demonstrate the existence of one and two-dimensional bright solitons in
the Bose-Einstein condensate with repulsive dipole-dipole interactions induced
by a combination of dc and ac polarizing fields, oriented perpendicular to the
plane in which the BEC is trapped, assuming that the strength of the fields
grows in the radial ($r$) direction faster than $r^{3}$. Stable tightly
confined 1D and 2D fundamental solitons, twisted solitons in 1D, and solitary
vortices in 2D are found in a numerical form. The fundamental solitons remain
robust under the action of an expulsive potential, which is induced by the
interaction of the dipoles with the polarizing field. The confinement and
scaling properties of the soliton families are explained analytically. The
Thomas-Fermi approximation is elaborated for fundamental solitons. The mobility
of the fundamental solitons is limited to the central area. Stable 1D even and
odd solitons are also found in the setting with a double-well modulation
function, along with a regime of Josephson oscillations.


title: Degeneracies in triple gravitational microlensing

abstract:
  We study microlensing light curves by a triple lens, in particular, by a
primary star plus two planets. A four-fold degeneracy is confirmed in the light
curves, similar to the close and wide degeneracy found in a double lens.
Furthermore, we derive a set of equations for triple-lens in the external shear
approximation. By using these external shear equations, we identify two kinds
of continuous degeneracies which may confused double and triple lenses, i.e.
the continuous external shear degeneracy among triple-lens systems and the
double-triple lens degeneracy. These degeneracies are particularly important in
high magnification events, and thus some caution needs to be applied when one
infers the fraction of stars hosting multiple planets from microlensing. We
study the dependence of the degeneracies on the lensing parameters (e.g.,
source trajectory) and give recipes about how the degeneracies should be
explored with real data.


title:
Applying the effective-source approach to frequency-domain self-force
  calculations

abstract:
  The equations of motion of a point particle interacting with its own field
are defined in terms of a certain regularized self-field. Two of the leading
methods for computing this regularized field are the mode-sum and
effective-source approaches. In this work we unite these two distinct
regularization schemes by generalizing traditional frequency-domain mode-sum
calculations to incorporate effective-source techniques. For a toy scalar-field
model we analytically compute an appropriate puncture field from which the
regularized residual field can be calculated. To demonstrate the method, we
compute the self-force for a scalar particle on a circular orbit in
Schwarzschild spacetime. We also demonstrate the relation between the worldtube
and window function approaches to localizing the puncture field to the
neighborhood of the worldline and show how the method reduces to the well-known
mode-sum regularization scheme in a certain limit. This new computational
scheme can be applied to cases where traditional mode-sum regularization is
inadequate, such as in calculations at second perturbative order.


title: k-DAG Based Lifetime Aware Data Collection in Wireless Sensor Networks

abstract:
  Wireless Sensor Networks need to be organized for efficient data collection
and lifetime maximization. In this paper, we propose a novel routing structure,
namely k-DAG, to balance the load of the base station's neighbours while
providing the worst-case latency guarantee for data collection, and a
distributed algorithm for construction a k-DAG based on a SPD (Shortest Path
DAG). In a k-DAG, the lengths of the longest path and the shortest path of each
sensor node to the base station differ by at most k. By adding sibling edges to
a SPD, our distributed algorithm allows critical nodes to have more routing
choices. The simulation results show that our approach significantly
outperforms the SPD-based data collection approach in both network lifetime and
load balance.


title:
Manipulating Mn--Mg$_k$ cation complexes to control the charge- and
  spin-state of Mn in GaN

abstract:
  Owing to the variety of possible charge and spin states and to the different
ways of coupling to the environment, paramagnetic centres in wide band-gap
semiconductors and insulators exhibit a strikingly rich spectrum of properties
and functionalities, exploited in commercial light emitters and proposed for
applications in quantum information. Here we demonstrate, by combining
synchrotron techniques with magnetic, optical and \emph{ab initio} studies,
that the codoping of GaN:Mn with Mg allows to control the Mn$^{n+}$ charge and
spin state in the range $3\le n\le 5$ and $2\ge S\ge 1$. According to our
results, this outstanding degree of tunability arises from the formation of
hitherto concealed cation complexes Mn-Mg$_k$, where the number of ligands $k$
is pre-defined by fabrication conditions. The properties of these complexes
allow to extend towards the infrared the already remarkable optical
capabilities of nitrides, open to solotronics functionalities, and generally
represent a fresh perspective for magnetic semiconductors.


title: Electroweak Effective Operators and Higgs Physics

abstract:
  We derive bounds from oblique parameters on the dimension-6 operators of an
effective field theory of electroweak gauge bosons and the Higgs doublet. The
loop- induced contributions to the S, T, and U oblique parameters are sensitive
to these contributions and we pay particular attention to the role of
renormalization when computing loop corrections in the effective theory. Limits
on the coefficients of the effective theory from loop contributions to oblique
parameters yield complementary information to direct Higgs production
measurements.


title:
A Simple Proof of Global Existence for the 1D Pressureless Gas Dynamics
  Equations

abstract:
  Sticky particle solutions to the one-dimensional pressureless gas dynamics
equations can be constructed by a suitable metric projection onto the cone of
monotone maps, as was shown in recent work by Natile and Savar\'{e}. Their
proof uses a discrete particle approximation and stability properties for first
order differential inclusions. Here we give a more direct proof that relies on
a result by Haraux on the differentiability of metric projections. We apply the
same method also to the one-dimensional Euler-Poisson system, obtaining a new
proof for the global existence of weak solutions.


title:
Representative functions on discrete groupoids and duality with Hopf
  algebroids

abstract:
  The aim of this paper is to establish a duality between the category of
discrete groupoids and the category of geometrically transitive commutative
Hopf algebroids in the sense of P. Deligne and A. Brugui\`eres. In one
direction we have the usual contravariant functor which assigns to each Hopf
algebroid its characters groupoid (the fiber groupoid at the ground field). In
the other direction we construct the contravariant functor which associated to
each discrete groupoid its Hopf algebroid of representative functions. This
duality extends the well known duality between discrete groups and commutative
Hopf algebras, and also sheds light on a new approach to Tannaka-Krein duality
for compact topological groupoids. Our results are supported by several
illustrative examples including topological ones.


title: Frequency Dependence of the Supersolid Signature in Polycrystalline 4He

abstract:
  We report studies, using a two mode torsional oscillator, of the putative
supersolid signature in polycrystalline 4He. Measurements at two frequencies
enable us to eliminate the viscoelastic contribution to the signature, and
other instrumental effects arising from the temperature dependent shear modulus
of the sample. The complex response function of the sample, encoded via its
effective moment of inertia, shows an unexpected and unexplained frequency
dependence. This cannot be accounted for by glassy dynamics within the sample.
The results do not rule out the possibility of supersolidity in bulk solid 4He.
?


title: Dark matter as a ghost free conformal extension of Einstein theory

abstract:
  We discuss ghost free models of the recently suggested mimetic dark matter
theory. This theory is shown to be a conformal extension of Einstein general
relativity. Dark matter originates from gauging out its local Weyl invariance
as an extra degree of freedom which describes a potential flow of the
pressureless perfect fluid. For a positive energy density of this fluid the
theory is free of ghost instabilities, which gives strong preference to stable
configurations with a positive scalar curvature and trace of the matter stress
tensor. Instabilities caused by caustics of the geodesic flow, inherent in this
model, serve as a motivation for an alternative conformal extension of Einstein
theory, based on the generalized Proca vector field. A potential part of this
field modifies the inflationary stage in cosmology, whereas its rotational part
at the post inflationary epoch might simulate rotating flows of dark matter.


title: Quantum turbulence in superfluids with wall-clamped normal component

abstract:
  In Fermi superfluids, like superfluid 3He, the viscous normal component can
be considered to be stationary with respect to the container. The normal
component interacts with the superfluid component via mutual friction which
damps the motion of quantized vortex lines and eventually couples the
superfluid component to the container. With decreasing temperature and mutual
friction the internal dynamics of the superfluid component becomes more
important compared to the damping and coupling effects from the normal
component. This causes profound changes in superfluid dynamics: the
temperature-dependent transition from laminar to turbulent vortex motion and
the decoupling from the reference frame of the container at even lower
temperatures.


title: New upper and lower bounds for the additive degree-Kirchhoff index

abstract:
  Given a simple connected graph on $N$ vertices with size $|E|$ and degree
sequence $d_{1}\leq d_{2}\leq ...\leq d_{N}$, the aim of this paper is to
exhibit new upper and lower bounds for the additive degree-Kirchhoff index in
closed forms, not containing effective resistances but a few invariants
$(N,|E|$ and the degrees $d_{i}$) and applicable in general contexts. In our
arguments we follow a dual approach: along with a traditional toolbox of
inequalities we also use a relatively newer method in Mathematical Chemistry,
based on the majorization and Schur-convex functions. Some theoretical and
numerical examples are provided, comparing the bounds obtained here and those
previously known in the literature.


title: Prediction of high frequency intrinsic localized modes in Ni and Nb

abstract:
  It is found that in some metals an intrinsic localized mode may exist with
frequency above the top of the phonon spectrum. The necessary condition,
requiring sufficiently high ratio of quartic to cubic anharmonicity may be
fulfilled because of screening of the interaction between ions by free
electrons. Starting from the known literature values of the pair potentials we
have found that in Ni and Nb the derived localized mode condition is fulfilled.
MD simulations of the nonlinear dynamics of Ni and Nb confirmed that high
frequency ILMs may exist in these metals.


title:
Natural star-products on symplectic manifolds and related quantum
  mechanical operators

abstract:
  In this paper is considered a problem of defining natural star-products on
symplectic manifolds, admissible for quantization of classical Hamiltonian
systems. First, a construction of a star-product on a cotangent bundle to an
Euclidean configuration space is given with the use of a sequence of pair-wise
commuting vector fields. The connection with a covariant representation of such
a star-product is also presented. Then, an extension of the construction to
symplectic manifolds over flat and non-flat pseudo-Riemannian configuration
spaces is discussed. Finally, a coordinate free construction of related quantum
mechanical operators from Hilbert space over respective configuration space is
presented.


title:
Defect thermodynamics and kinetics in thin strained ferroelectric films:
  the interplay of possible mechanisms

abstract:
  We present a theoretical description of the influence of misfit strain on
mobile defects dynamics in thin strained ferroelectric films. Self-consistent
solutions obtained by coupling the Poissons equation for electric potential
with continuity equations for mobile donor and electron concentrations and
time-dependent Landau-Ginzburg-Devonshire equations reveal that the Vegard
mechanism (chemical pressure) leads to the redistribution of both charged and
electro-neutral defects in order to decrease the effective stress in the film.
Internal electric fields, both built-in and depolarization ones, lead to a
strong accumulation of screening space charges (charged defects and electrons)
near the film interfaces. Importantly, the corresponding screening length is
governed by the misfit strain and Vegard coefficient. Mobile defects dynamics,
kinetics of polarization and electric current reversal are defined by the
complex interplay between the donor, electron and phonon relaxation times,
misfit strain, finite size effect and Vegard stresses.


title:
Fokker-Planck approach to the theory of magnon-driven spin Seebeck
  effect

abstract:
  Following the theoretical approach by Xiao et al [Phys. Rev. B 81, 214418
(2010)] to the spin Seebeck effect, we calculate the mean value of the total
spin current flowing through a normalmetal/ ferromagnet interface. The spin
current emitted from the ferromagnet to the normal metal is evaluated in the
framework of the Fokker-Planck approach for the stochastic
Landau-Lifshitz-Gilbert equation. We show that the total spin current depends
not only on the temperature difference between the electron and the magnon
baths, but also on the external magnetic field and magnetic anisotropy. Apart
from this, the spin current is shown to saturate with increasing magnon
temperature, and the saturation temperature increases with increasing magnetic
field and/or magnetic anisotropy.


title: On high-dimensional sign tests

abstract:
  Sign tests are among the most successful procedures in multivariate
nonparametric statistics. In this paper, we consider several testing problems
in multivariate analysis, directional statistics and multivariate time series
analysis, and we show that, under appropriate symmetry assumptions, the
fixed-$p$ multivariate sign tests remain valid in the high-dimensional case.
Remarkably, our asymptotic results are universal, in the sense that, unlike in
most previous works in high-dimensional statistics, $p$ may go to infinity in
an arbitrary way as $n$ does. We conduct simulations that (i) confirm our
asymptotic results, (ii) reveal that, even for relatively large $p$, chi-square
critical values are to be favoured over the (asymptotically equivalent)
Gaussian ones and (iii) show that, for testing i.i.d.-ness against serial
dependence in the high-dimensional case, Portmanteau sign tests outperform
their competitors in terms of validity-robustness.


title:
Well-posedness and scattering for nonlinear Schr\"odinger equations with
  a derivative nonlinearity at the scaling critical regularity

abstract:
  In the present paper, we consider the Cauchy problem of nonlinear
Schr\"odinger equations with a derivative nonlinearity which depends only on
$\bar{u}$. The well-posedness of the equation at the scaling subcritical
regularity was proved by A. Gr\"unrock (2000). We prove the well-posedness of
the equation and the scattering for the solution at the scaling critical
regularity by using $U^{2}$ space and $V^{2}$ space which are applied to prove
the well-posedness and the scattering for KP-II equation at the scaling
critical regularity by Hadac, Herr and Koch (2009).


title:
Thermally activated in-plane magnetization rotation induced by spin
  torque

abstract:
  We study the role of thermal fluctuations on the spin dynamics of a thin
permalloy film with a focus on the behavior of spin torque and find that the
thermally assisted spin torque results in new aspects of the magnetization
dynamics. In particular, we uncover the formation of a finite, spin
torque-induced, in-plane magnetization component. The orientation of the
in-plane magnetization vector depends on the temperature and the spin-torque
coupling. We investigate and illustrate that the variation of the temperature
leads to a thermally-induced rotation of the in-plane magnetization.


title:
Simple Tabulation, Fast Expanders, Double Tabulation, and High
  Independence

abstract:
  Simple tabulation dates back to Zobrist in 1970. Keys are viewed as c
characters from some alphabet A. We initialize c tables h_0, ..., h_{c-1}
mapping characters to random hash values. A key x=(x_0, ..., x_{c-1}) is hashed
to h_0[x_0] xor...xor h_{c-1}[x_{c-1}]. The scheme is extremely fast when the
character hash tables h_i are in cache. Simple tabulation hashing is not
4-independent, but we show that if we apply it twice, then we get high
independence. First we hash to intermediate keys that are 6 times longer than
the original keys, and then we hash the intermediate keys to the final hash
values.
  The intermediate keys have d=6c characters from A. We can view the hash
function as a degree d bipartite graph with keys on one side, each with edges
to d output characters. We show that this graph has nice expansion properties,
and from that we get that with another level of simple tabulation on the
intermediate keys, the composition is a highly independent hash function. The
independence we get is |A|^{Omega(1/c)}.
  Our space is O(c|A|) and the hash function is evaluated in O(c) time. Siegel
[FOCS'89, SICOMP'04] proved that with this space, if the hash function is
evaluated in o(c) time, then the independence can only be o(c), so our
evaluation time is best possible for Omega(c) independence---our independence
is much higher if c=|A|^{o(1)}.
  Siegel used O(c)^c evaluation time to get the same independence with similar
space. Siegel's main focus was c=O(1), but we are exponentially faster when
c=omega(1).
  Applying our scheme recursively, we can increase our independence to
|A|^{Omega(1)} with o(c^{log c}) evaluation time. Compared with Siegel's scheme
this is both faster and higher independence.
  Our scheme is easy to implement, and it does provide realistic
implementations of 100-independent hashing for, say, 32 and 64-bit keys.


title: Spectral structure of transfer operators for expanding circle maps

abstract:
  We explicitly determine the spectrum of transfer operators (acting on spaces
of holomorphic functions) associated to analytic expanding circle maps arising
from finite Blaschke products. This is achieved by deriving a convenient
natural representation of the respective adjoint operators.


title: Polar Codes for Arbitrary DMCs and Arbitrary MACs

abstract:
  Polar codes are constructed for arbitrary channels by imposing an arbitrary
quasigroup structure on the input alphabet. Just as with "usual" polar codes,
the block error probability under successive cancellation decoding is
$o(2^{-N^{1/2-\epsilon}})$, where $N$ is the block length. Encoding and
decoding for these codes can be implemented with a complexity of $O(N\log N)$.
It is shown that the same technique can be used to construct polar codes for
arbitrary multiple access channels (MAC) by using an appropriate Abelian group
structure. Although the symmetric sum capacity is achieved by this coding
scheme, some points in the symmetric capacity region may not be achieved. In
the case where the channel is a combination of linear channels, we provide a
necessary and sufficient condition characterizing the channels whose symmetric
capacity region is preserved by the polarization process. We also provide a
sufficient condition for having a maximal loss in the dominant face.


title:
Conformally invariant wave equation for a symmetric second rank tensor
  ("spin-2") in d-dimensional curved background

abstract:
  We build the general conformally invariant linear wave operator for a free,
symmetric, second-rank tensor field in a d-dimensional ($d\geqslant 2$) metric
manifold, and explicit the special case of maximally symmetric spaces. Under
the assumptions made, this conformally invariant wave operator is unique. The
corresponding conformally invariant wave equation can be obtained from a
Lagrangian which is explicitly given. We discuss how our result compares to
previous works, in particular we hope to clarify the situation between
conflicting results.


title: The Pixel-TPC: first results from an 8-InGrid module

abstract:
  An eight chip InGrid module has been tested as readout of a prototype time
projection chamber. The construction of the modules as well as first
preliminary results are presented. The InGrids, a Micromegas like amplification
structure with a pixel ASIC, have been produced on wafer-level in a
photolithographic process. For the measurements a newly developed readout
system based on the Scalable Readout System was used.


title: Analyzing polarization swings in 3C 279

abstract:
  Quasar 3C 279 is known to exhibit episodes of optical polarization angle
rotation. We present new, well-sampled optical polarization data for 3C 279 and
introduce a method to distinguish between random and deterministic electric
vector position angle (EVPA) variations. We observe EVPA rotations in both
directions with different amplitudes and find that the EVPA variation shows
characteristics of both random and deterministic cases. Our analysis indicates
that the EVPA variation is likely dominated by a random process in the low
brightness state of the jet and by a deterministic process in the flaring
state.


title:
Collisionless microinstabilities in stellarators II - numerical
  simulations

abstract:
  Microinstabilities exhibit a rich variety of behavior in stellarators due to
the many degrees of freedom in the magnetic geometry. It has recently been
found that certain stellarators (quasi-isodynamic ones with maximum-$J$
geometry) are partly resilient to trapped-particle instabilities, because
fast-bouncing particles tend to extract energy from these modes near marginal
stability. In reality, stellarators are never perfectly quasi-isodynamic, and
the question thus arises whether they still benefit from enhanced stability.
Here the stability properties of Wendelstein 7-X and a more quasi-isodynamic
configuration, QIPC, are investigated numerically and compared with the
National Compact Stellarator Experiment (NCSX) and the DIII-D tokamak. In
gyrokinetic simulations, performed with the gyrokinetic code GENE in the
electrostatic and collisionless approximation, ion-temperature-gradient modes,
trapped-electron modes and mixed-type instabilities are studied. Wendelstein
7-X and QIPC exhibit significantly reduced growth rates for all simulations
that include kinetic electrons, and the latter are indeed found to be
stabilizing in the energy budget. These results suggest that imperfectly
optimized stellarators can retain most of the stabilizing properties predicted
for perfect maximum-$J$ configurations.


title:
Infinite-energy solutions for the Navier-Stokes equations in a strip
  revisited

abstract:
  The paper deals with the Navier-Stokes equations in a strip in the class of
spatially non-decaing (infinite-energy) solutions belonging to the properly
chosen uniformly local Sobolev spaces. The global well-posedness and
dissipativity of the Navier-Stokes equations in a strip in such spaces has been
first established in [S. Zelik, "Spatially nondecaying solutions of the 2D
Navier-Stokes equation in a strip". Glasg. Math. J., 49 (2007), no. 3,
525--588].
  However, the proof given there contains rather essential error and the aim of
the present paper is to correct this error and to show that the main results of
that paper remain true.


title: Subjective physics

abstract:
  Imagine a naive organism who does not know anything about the world. It can
capture signals through its sensors and it can make actions. What kind of
knowledge about the world is accessible to the organism? This situation is
analog to that of a physicist trying to understand the world through
observations and experiments. In the same way as physics describes the laws of
the world obtained in this way by the scientist, I propose to name subjective
physics the description of the laws that govern sensory signals and their
relationships with actions, as observed from the perspective of the perceptual
system of the organism. In this text, I present the main concepts of subjective
physics, illustrated with concrete examples.


title: Impact of Indentation in Programming

abstract:
  In computer programming languages, indentation formats program source code to
improve readability. Programming languages make use of indentation to define
program structure .Programmers use indentation to understand the structure of
their programs to human readers. Especially, indentation is the better way to
represent the relationship between control flow constructs such as selection
statements or loops and code contained within and outside them. This paper
describes about different indentation styles used in Programming and also
describes context of each indentation style. It also describes indentation
styles used for various programming constructs and the best practice for a
particular programming construct. This paper helps the beginners to understand
various indentation styles used in programming and also to choose suitable
indentation style.


title: A spherically-symmetric charged-dS solution in f(T) gravity theories

abstract:
  A tetrad field with spherical symmetry is applied to the charged field
equations of $f(T)$ gravity theory. A special spherically-symmetric charged-dS
solution is obtained. The scalar torsion of this solution is a vanishing
quantity. The spacetime of the derived solution is rewritten as a
multiplication of three matrices: The first matrix is a special case of
Euler$'$s angle "so(3)", the second matrix represents a boost transformation,
while the third matrix is the square root of the spherically-symmetric
charged-dS metric. It is shown that the boost matrix is important because it
plays an essential role in adjusting the spacetime to become a solution for
$f(T)$ theory.


title: The collision between two hydrogen atoms

abstract:
  The electron-electron correlation term in two-atomic collision is the most
important, most difficult term to obtain the effective interatomic potential.
Generally the H and H collision is a four center problem. It is extremely
difficult to compute the electron-electron correlation term to include the
effect of exchange or antisymmetry between two system electrons exactly. All
the two-atomic collision related theoretical data differ from each other due to
its difference in approximating the electron-electron correlation term. I
invent a trick to evaluate the term exactly. Earlier the positronium (Ps) and H
system was easily approximated as a three center problem due to the light mass
of Ps. My new code for H-H collision using the ab-initio and exact
static-exchange model (SEM) can reproduce exactly the same data of Ps and H
system just by using the appropriate atomic parameters. The success of the
present trick makes the foundation of a big monument in cold and low energy
atomic collision physics. The Feshbach resonances are observed in H(1s)-H(1s)
elastic scattering in both the singlet and triplet channels. One can use the
trick to solve any four center problem including excitation and ionization
processes. Again one can use the idea in larger systems too.


title: Hadronic total cross sections at high energy and the QCD spectrum

abstract:
  We show how to obtain the leading energy dependence of hadronic total cross
sections, in the framework of the nonperturbative approach to soft high-energy
scattering based on Wilson-loop correlation functions, if certain nontrivial
analyticity assumptions are satisfied. The total cross sections turn out to be
of "Froissart" type, $\sigma_{\rm tot}^{(hh)}(s) \mathop\sim B\log^2 s$ for ${s
\to
  \infty}$. We also discuss under which conditions the coefficient $B$ is
universal, i.e., independent of the hadrons involved in the scattering process.
In the most natural scenarios for universality, $B$ can be related to the
stable spectrum of QCD, and is predicted to be $B_{\rm th}\simeq 0.22~{\rm
mb}$, in fair agreement with experimental results. If we consider, instead, the
stable spectrum of the quenched (i.e., pure-gauge) theory, we obtain a quite
larger value $B^{(Q)}_{\rm th} \ge 0.42~{\rm mb}$, suggesting (quite
surprisingly) large unquenching effects due to the sea quarks.


title:
Fredholm alternative, semilinear elliptic problems, and Wentzell
  boundary conditions

abstract:
  We give necessary and sufficient conditions for the solvability of some
semilinear elliptic boundary value problems involving the Laplace operator with
linear and nonlinear highest order boundary conditions involving the
Laplace-Beltrami operator.


title: Planck-scale dimensional reduction without a preferred frame

abstract:
  Several approaches to quantum gravity suggest that the standard description
of spacetime as probed at low-energy, with four dimensions, is replaced in the
Planckian regime by a spacetime with a spectral dimension of two. The
implications for relativistic symmetries can be momentous, and indeed the most
tangible picture for "running" of the spectral dimension, found within
Horava-Lifschitz gravity, requires the breakdown of relativity of inertial
frames. In this Letter we incorporate running spectral dimensions in a scenario
that does not require the emergence of a preferred frame. We consider the best
studied mechanism for deforming relativistic symmetries whilst preserving the
relativity of inertial frames, based on a momentum space with curvature at the
Planck scale. We show explicitly how running of the spectral dimension can be
derived from these models.


title: Quantum corrections to extremal black brane solutions

abstract:
  We discuss quantum corrections to extremal black brane solutions in N=2 U(1)
gauged supergravity in four dimensions. We consider modifications due to a
certain class of higher-derivative terms as well as perturbative corrections to
the prepotential. We use the entropy function formalism to assess the impact of
these corrections on singular brane solutions and we give a few examples. We
then use first-order flow equations to construct solutions that interpolate
between quantum corrected fixed points of the associated potentials.


title: QCD effective potential with strong U(1)_{em} magnetic fields

abstract:
  We derive the analytic expression for the one-loop $SU(N_{c})$ QCD effective
potential including $N_{f}$ flavor quarks which non-linearly interact with the
chromo-magnetic background field and the external $U(1)_{em}$ magnetic field.
After the renormalization of couplings and fields, we obtain the correct
one-loop $\beta$ functions of both QCD and QED, and the resulting effective
potential satisfies the renormalization group equation. We investigate the
effect of the magnetic field on the QCD vacuum by using the effective
potential, in particular for the color $SU(3)$ case with the three flavors ($u,
d, s$). Our result shows that the chromo-magnetic field prefers to be parallel
to the external magnetic field. Furthermore, quark loop contributions to the
effective potential with the magnetic field enhance gluonic contributions, and
then the chromo-magnetic condensate increases with an increasing magnetic
field. This result supports the recent observed gluonic magnetic catalysis at
zero-temperature in lattice QCD.


title: Bredon Cohomology, K theory and K homology of Pullbacks of groups

abstract:
  We develop an Eilenberg-Moore spectral sequence to compute Bredon cohomology
of spaces with an action of a group given as a pullback. Using several other
spectral sequences, and positive results on the Baum-Connes Conjecture, we are
able to compute Equivariant K-theory and K-Homology of the reduced group
C*-algebra of a 6-dimensional crystallographic group $\Gamma$ introduced by
Vafa and Witten. We also use positive results on the Farrell-Jones Conjecture
to give a vanishing result for the negative algebraic K-theory of the integral
group ring of $\Gamma$.


title: Entropy Assessment of Windows OS Performance Counters

abstract:
  The security of many cryptographic constructions depends on random number
generators for providing unpredictable keys, nonces, initialization vectors and
other parameters. Modern operating systems implement cryptographic
pseudo-random number generators (PRNGs) to fulfill this need. Performance
counters and other system parameters are often used as a low-entropy source to
initialize (seed) the generators. We perform an experiment to analyze all
performance counters in standard installation of Microsoft Windows 7 operating
system, and assess their suitability as entropy sources. Besides selecting top
19 counters, we analyze their mutual information (independence) as well as
robustness in the virtual environment. Final selection contains 14 counters
with sufficient overall entropy for practical applications.


title:
Simultaneous double transformations of functions depending on space and
  time

abstract:
  It is shown that performing simultaneously two transformations on functions
of space and time (for instance a Fourier transform on the space variable and a
Laplace transform on the time variable) can be easier than performing them one
after the other when the variables are combined in invariant quantities. This
is naturally also true when performing two inverse transforms simultaneously,
when the conjugated variables are combined into a propagator. An immediate
application is found in the computation of the solutions of partial
differential equations. This article contains several general examples of such
"simultaneous double transforms" for arbitrary analytic functions of space and
time.


title: Cloud Compute-and-Forward with Relay Cooperation

abstract:
  We study a cloud network with M distributed receiving antennas and L users,
which transmit their messages towards a centralized decoder (CD), where M>=L.
We consider that the cloud network applies the Compute-and-Forward (C&F)
protocol, where L antennas/relays are selected to decode integer equations of
the transmitted messages. In this work, we focus on the best relay selection
and the optimization of the Physical-Layer Network Coding (PNC) at the relays,
aiming at the throughput maximization of the network. Existing literature
optimizes PNC with respect to the maximization of the minimum rate among users.
The proposed strategy maximizes the sum rate of the users allowing nonsymmetric
rates, while the optimal solution is explored with the aid of the Pareto
frontier. The problem of relay selection is matched to a coalition formation
game, where the relays and the CD cooperate in order to maximize their profit.
Efficient coalition formation algorithms are proposed, which perform joint
relay selection and PNC optimization. Simulation results show that a
considerable improvement is achieved compared to existing results, both in
terms of the network sum rate and the players' profits.


title: Large Frame-Transfer Detectors for the MAIA Imager

abstract:
  MAIA, the Mercator Advanced Imager for Asteroseismology, is a new
fast-cadence 3-channel photometric instrument. It is installed on the 1.2-m
Mercator telescope at the Roque de Los Muchachos Observatory in La Palma,
Spain. MAIA comprises 3 cameras that simultaneously observe the same 9.4 x 14.1
arcmin field in 3 different colour bands (u, g and r). Each camera is based on
a very large frame-transfer detector (CCD42-C0) of 2kx6k pixels, specially
designed for rapid time-series photometry. These CCDs were originally developed
by e2v for ESA's cancelled Eddington space mission and are now on permanent
loan to the Institute of Astronomy of the KU Leuven, Belgium. The acquisition
system of MAIA uses a single ARC GEN-III controller, custom programmed to allow
differing exposure times for each of the three CCDs. Predefined sequences
synchronize each read-out with the shortest integration time. Detectors that
are not read-out at the end of an exposure continue integrating and can be
read-out in one of the subsequent cycles. This read method takes full advantage
of the frame-transfer functionality of the CCD42-C0 detectors and allows
optimisation of the exposure times for each wavelength band. This then gives a
similar exposure depth in each of the 3 arms despite the fact that the UV
channel typically sees much less flux. We present the CCD42-C0 detectors, their
characterisation, including a thorough analysis of their non-linearity, and the
MAIA data-acquisition system.


title:
Simultaneous state-time approximation of the chemical master equation
  using tensor product formats

abstract:
  We study the application of the novel tensor formats (TT, QTT, QTT-Tucker) to
the solution of $d$-dimensional chemical master equations, applied mostly to
gene regulating networks (signaling cascades, toggle switches,
phage-$\lambda$). For some important cases, e.g. signaling cascade models, we
prove good separability properties of the system operator. The Quantized tensor
representations (QTT, QTT-Tucker) are employed in both state space and time,
and the global state-time $(d+1)$-dimensional system is solved in the
structured form by using the ALS-type iteration. This approach leads to the
logarithmic dependence of the computational complexity on the system size. When
possible, we compare our approach with the direct CME solution and some
previously known approximate schemes, and observe a good potential of the newer
tensor methods in simulation of relevant biological systems.


title: Recent Advances in Graph Partitioning

abstract:
  We survey recent trends in practical algorithms for balanced graph
partitioning together with applications and future research directions.


title: Isotrivially fibred surfaces and their numerical invariants

abstract:
  We give a survey of our previous work on relatively minimal isotrivial
fibrations $\alpha \colon X \to C$, where $X$ is a smooth, projective surface
and $C$ is a curve. In particular, we consider two inequalities involving the
numerical invariants $K_X^2$ and $\chi(\mathcal{O}_X)$ and we illustrate them
by means of several examples and counterexamples.


title:
Self Sustained Traversable Wormholes and Topology Change Induced by
  Gravity's Rainbow

abstract:
  We consider the effects of Gravity's Rainbow on the self-sustained equation
which is responsible to find new traversable wormholes configurations which are
sustained by their own gravitational quantum fluctuations. The same
self-sustained equation is also used to discover if topology change is
possible. In this contribution, we will show that in both uses, the
self-sustained equation will produce a Wheeler wormhole, namely a wormhole of
Planckian size. This means that, from the point of view of traversability, the
wormhole will be traversable in principle, but not in practice. From the
topology change point of view, the background metric will be fixed to be
Minkowskian in the equation governing the quantum fluctuations, which behaves
essentially as a backreaction equation, and the quantum fluctuations are let to
evolve. Analyzing this procedure, we will show that the self-sustained
equation, endowed with a Gravity's Rainbow distortion, will be responsible of a
topology change with the appearance of a Planckian wormhole.


title: A DFT+Nonhomogeneous DMFT approach for Finite Systems

abstract:
  For reliable and efficient inclusion of electron-electron correlation effects
in nanosystems we propose a combined density-functional-theory/nonhomogeneous
dynamical-mean-field-theory (DFT + DMFT) approach which employs an approximate
Iterative Perturbative Theory (IPT) impurity solver. The validity of the method
is demonstrated by successful examination of the size-dependent magnetic
properties of iron nanoparticles containing 11-100 atoms. We show that the DFT+
DMFT solution is in very good agreement with experimental data, in particular
it does not lead to the overestimation of magnetization that is found with the
DFT and DFT+U techniques. More importantly, we demonstrate that DFT+DMFT
approach can be used for accurate and realistic description of nanosystems
containing about hundred atoms.


title:
Constraints on axionlike particles with H.E.S.S. from the irregularity
  of the PKS 2155-304 energy spectrum

abstract:
  Axionlike particles (ALPs) are hypothetical light (sub-eV) bosons predicted
in some extensions of the Standard Model of particle physics. In astrophysical
environments comprising high-energy gamma rays and turbulent magnetic fields,
the existence of ALPs can modify the energy spectrum of the gamma rays for a
sufficiently large coupling between ALPs and photons. This modification would
take the form of an irregular behavior of the energy spectrum in a limited
energy range. Data from the H.E.S.S. observations of the distant BL Lac object
PKS 2155-304 (z = 0.116) are used to derive upper limits at the 95% C.L. on the
strength of the ALP coupling to photons, $g_{\gamma a} < 2.1\times 10^{-11}$
GeV$^{-1}$ for an ALP mass between 15 neV and 60 neV. The results depend on
assumptions on the magnetic field around the source, which are chosen
conservatively. The derived constraints apply to both light pseudoscalar and
scalar bosons that couple to the electromagnetic field.


title:
Local Event Boundary Detection with Unreliable Sensors: Analysis of the
  Majority Vote Scheme

abstract:
  In this paper we study the identification of an event region $X$ within a
larger region $Y$, in which the sensors are distributed by a Poisson process of
density $\lambda$ to detect this event region, i.e., its boundary. The model of
sensor is a 0-1 sensor that decides whether it lies in $X$ or not, and which
might be incorrect with probability $p$. It also collects information on the
0-1 values of the neighbors within some distance $r$ and revises its decision
by the majority vote of these neighbors. In the most general setting, we
analyze this simple majority vote scheme and derive some upper and lower bounds
on the expected number of misclassified sensors. These bounds depend on several
sensing parameters of $p$, $r$, and some geometric parameters of the event
region $X$. By making some assumptions on the shape of $X$, we prove a
significantly improved upper bound on the expected number of misclassified
sensors; especially for convex regions with sufficiently round boundary, and we
find that the majority vote scheme performs well in the simulation rather than
its theoretical upper bound.


title:
Density-Dependent Synthetic Gauge Fields Using Periodically Modulated
  Interactions

abstract:
  We show that density-dependent synthetic gauge fields may be engineered by
combining periodically modu- lated interactions and Raman-assisted hopping in
spin-dependent optical lattices. These fields lead to a density- dependent
shift of the momentum distribution, may induce superfluid-to-Mott insulator
transitions, and strongly modify correlations in the superfluid regime. We show
that the interplay between the created gauge field and the broken sublattice
symmetry results, as well, in an intriguing behavior at vanishing interactions,
characterized by the appearance of a fractional Mott insulator.


title: Introducing Accountability to Anonymity Networks

abstract:
  Many anonymous communication (AC) networks rely on routing traffic through
proxy nodes to obfuscate the originator of the traffic. Without an
accountability mechanism, exit proxy nodes risk sanctions by law enforcement if
users commit illegal actions through the AC network. We present BackRef, a
generic mechanism for AC networks that provides practical repudiation for the
proxy nodes by tracing back the selected outbound traffic to the predecessor
node (but not in the forward direction) through a cryptographically verifiable
chain. It also provides an option for full (or partial) traceability back to
the entry node or even to the corresponding user when all intermediate nodes
are cooperating. Moreover, to maintain a good balance between anonymity and
accountability, the protocol incorporates whitelist directories at exit proxy
nodes. BackRef offers improved deployability over the related work, and
introduces a novel concept of pseudonymous signatures that may be of
independent interest.
  We exemplify the utility of BackRef by integrating it into the onion routing
(OR) protocol, and examine its deployability by considering several
system-level aspects. We also present the security definitions for the BackRef
system (namely, anonymity, backward traceability, no forward traceability, and
no false accusation) and conduct a formal security analysis of the OR protocol
with BackRef using ProVerif, an automated cryptographic protocol verifier,
establishing the aforementioned security properties against a strong
adversarial model.


title:
Exercises in simplest dynamical random walk, or Quantum path integral
  approach to true diffusion law and 1/f noise of classical particle
  interacting with ideal gas

abstract:
  Statistics of classical Hamiltonian random walk of particle colliding with
atoms of ideal gas is considered from viewpoint of earlier suggested exact
pseudo-quantum path integral representation of the problem, and qualitative
agreement is demostrated between results of an naturally arising simple
approximation of this integral and results obtained by formally different
methods, thus in a new fashion showing inevitability of scaleless 1/f-type
fluctuations in rates of molecular Brownian motions and other dynamical
transport and evolution processes.


title:
Limiting alternative theories of gravity using gravitational wave
  observations across the spectrum

abstract:
  The advent of gravitational wave astronomy provides new proving grounds for
testing theories of gravity. Recent work has reinvigorated the study of
bimetric theories of gravity and massive gravity theories. One of the most
interesting predictions of these theories, as well as some string theories, is
the subluminal speed of propagating gravitational waves. Multi-messenger
astronomy provides a unique opportunity to put limits on the difference (either
positive or negative) between the propagation speed of electromagnetic and
gravitational waves from these sources. This paper considers limits from
multi-messenger cases across the planned measurable spectrum: first, the limits
from isolated pulsars based on the current best limits from LIGO on
gravitational wave emission, second, the limits from ultra-compact binaries
that will be visible to a low-frequency space-based gravitational wave
observatory like LISA, and third, limits from super massive black hole binaries
using pulsar timing arrays. The required phase comparison between the
electromagnetic signal and the gravitational wave signal is derived and,
assuming a null result in that comparison, the current bounds on emission are
used to place limits on alternative theories that exhibit propagation delays.
Observations of the pulsars in the most sensitive range of LIGO could put an
upper limit on the graviton mass as low as $10^{-38}\frac{eV}{c^{2}}$ and an
upper limit on the fractional difference between the gravitational wave and
electromagnetic wave speeds as low as $10^{-9}$. This paper shows results from
the initial LIGO limit catalog of known pulsars. The bounds are stronger for
binaries. A LISA-like mission bounds $m_{g}<10^{-40}\frac{eV}{c^{2}}$ and
$\delta<10^{-12}$. A PTA source gives even better bounds of
$m_{g}<10^{-45}\frac{eV}{c^{2}}$ and $\delta<10^{-14}$.