title: The homotopy theory of cyclotomic spectra

abstract:
  We describe spectral model category structures on the categories of
cyclotomic spectra and $p$-cyclotomic spectra (in orthogonal spectra) with
triangulated homotopy categories. We show that the functors $TR$ and $TC$ are
corepresentable in these categories. Specifically, the derived mapping spectrum
out of the sphere spectrum in the category of cyclotomic spectra corepresents
the finite completion of $TC$ and the derived mapping spectrum out of the
sphere spectrum in the category of $p$-cyclotomic spectra corepresents the
$p$-completion of $TC(-;p)$.


title: Effect of Query Formation on Web Search Engine Results

abstract:
  Query in a search engine is generally based on natural language. A query can
be expressed in more than one way without changing its meaning as it depends on
thinking of human being at a particular moment. Aim of the searcher is to get
most relevant results immaterial of how the query has been expressed. In the
present paper, we have examined the results of search engine for change in
coverage and similarity of first few results when a query is entered in two
semantically same but in different formats. Searching has been made through
Google search engine. Fifteen pairs of queries have been chosen for the study.
The t-test has been used for the purpose and the results have been checked on
the basis of total documents found, similarity of first five and first ten
documents found in the results of a query entered in two different formats. It
has been found that the total coverage is same but first few results are
significantly different.


title:
Classical formulations of the electromagnetic self-force of extended
  charged bodies

abstract:
  Several noncovariant formulations of the electromagnetic self-force of
extended charged bodies, as have been developed in the context of classical
models of charged particles, are compared. The mathematical equivalence of the
various dissimilar self-force expressions is demonstrated explicitly by
deriving these expressions directly from one another. The applicability of the
self-force formulations and their significance in the wider context of
classical charged particle models are discussed.


title: Secure Video Streaming Plug-In

abstract:
  Video sharing sites like YouTube, Metacafe, Dailymotion, Vimeo, etc. provide
a platform for media content sharing among its users. Some of these videos are
copyright protected and restricted from being downloaded and saved. But users
can use various download managers or application programs to download and save
these videos. This affects the incoming traffic on these websites reducing
their hit rate and consequently reducing their revenue. Adobe Flash Player is
the most commonly used player for watching online videos. It uses RTMP (Real
Time Messaging Protocol) to stream audio, video and data over the Internet,
between a Flash Player and Adobe Flash Media Server.Here, we propose a plug-in
that enables the site owner control over downloading of videos from such
website. The plug-in will be installed at the client side with the consent of
the user. When the video is being played this plug-in will send unique keys to
the media server. The server will continue streaming the video after verifying
the keys. Download managers or application programs will not be able to
download the videos as they wont be able to create the unique keys that need to
be sent to the server.


title:
Adaptive quantile estimation in deconvolution with unknown error
  distribution

abstract:
  Quantile estimation in deconvolution problems is studied comprehensively. In
particular, the more realistic setup of unknown error distributions is covered.
Our plug-in method is based on a deconvolution density estimator and is minimax
optimal under minimal and natural conditions. This closes an important gap in
the literature. Optimal adaptive estimation is obtained by a data-driven
bandwidth choice. As a side result, we obtain optimal rates for the plug-in
estimation of distribution functions with unknown error distributions. The
method is applied to a real data example.


title:
Local well-posedness for the nonlinear Dirac equation in two space
  dimensions

abstract:
  The Cauchy problem for the cubic nonlinear Dirac equation in two space
dimensions is locally well-posed for data in H^s for s > 1/2. The proof given
in spaces of Bourgain-Klainerman-Machedon type relies on the null structure of
the nonlinearity as used by d'Ancona-Foschi-Selberg for the Dirac-Klein-Gordon
system before and bilinear Strichartz type estimates for the wave equation by
Selberg and Foschi-Klainerman.


title:
K-Nearest Neighbour algorithm coupled with logistic regression in
  medical case-based reasoning systems. Application to prediction of access to
  the renal transplant waiting list in Brittany

abstract:
  Introduction. Case Based Reasoning (CBR) is an emerg- ing decision making
paradigm in medical research where new cases are solved relying on previously
solved similar cases. Usually, a database of solved cases is provided, and
every case is described through a set of attributes (inputs) and a label
(output). Extracting useful information from this database can help the CBR
system providing more reliable results on the yet to be solved cases.
Objective. For that purpose we suggest a general frame- work where a CBR
system, viz. K-Nearest Neighbor (K-NN) algorithm, is combined with various
information obtained from a Logistic Regression (LR) model. Methods. LR is
applied, on the case database, to assign weights to the attributes as well as
the solved cases. Thus, five possible decision making systems based on K-NN
and/or LR were identified: a standalone K-NN, a standalone LR and three soft
K-NN algorithms that rely on the weights based on the results of the LR. The
evaluation of the described approaches is performed in the field of renal
transplant access waiting list. Results and conclusion. The results show that
our suggested approach, where the K-NN algorithm relies on both weighted
attributes and cases, can efficiently deal with non relevant attributes,
whereas the four other approaches suffer from this kind of noisy setups. The
robustness of this approach suggests interesting perspectives for medical
problem solving tools using CBR methodology.


title: A note on trace fields of complex hyperbolic groups

abstract:
  We show that if $\Gamma$ is an irreducible subgroup of ${\rm SU}(2,1)$, then
$\Gamma$ contains a loxodromic element $A$. If $A$ has eigenvalues $\lambda_1 =
\lambda e^{i\varphi},$ $\lambda_2 = e^{-2i\varphi}$, $\lambda_3 =
\lambda^{-1}e^{i\varphi}$, we prove that $\Gamma$ is conjugate in ${\rm
SU}(2,1)$ to a subgroup of ${\rm SU}(2,1,\mathbb{Q}(\Gamma,\lambda)),$ where
$\mathbb{Q}(\Gamma, \lambda)$ is the field generated by the trace field
$\mathbb{Q}(\Gamma)$ of $\Gamma$ and $\lambda$. It follows from this that if
$\Gamma$ is an irreducible subgroup of ${\rm SU}(2,1)$ such that the trace
field $\mathbb{Q}(\Gamma)$ is real, then $\Gamma$ is conjugate in ${\rm
SU}(2,1)$ to a subgroup of ${\rm SO}(2,1)$. As a geometric application of the
above, we get that if $G$ is an irreducible discrete subgroup of ${\rm
PU}(2,1)$, then $G$ is an $\mathbb{R}$-Fuchsian subgroup of ${\rm PU}(2,1)$ if
and only if the invariant trace field $k(G)$ of $G$ is real.


title:
Characterizing N-dimensional anisotropic Brownian motion by the
  distribution of diffusivities

abstract:
  Anisotropic diffusion processes emerge in various fields such as transport in
biological tissue and diffusion in liquid crystals. In such systems, the motion
is described by a diffusion tensor. For a proper characterization of processes
with more than one diffusion coefficient an average description by the mean
squared displacement is often not sufficient. Hence, in this paper, we use the
distribution of diffusivities to study diffusion in a homogeneous anisotropic
environment. We derive analytical expressions of the distribution and relate
its properties to an anisotropy measure based on the mean diffusivity and the
asymptotic decay of the distribution. Both quantities are easy to determine
from experimental data and reveal the existence of more than one diffusion
coefficient, which allows the distinction between isotropic and anisotropic
processes. We further discuss the influence on the analysis of projected
trajectories, which are typically accessible in experiments. For the
experimentally relevant cases of two- and three-dimensional anisotropic
diffusion we derive specific expressions, determine the diffusion tensor,
characterize the anisotropy, and demonstrate the applicability for simulated
trajectories.


title: Concept-based indexing in text information retrieval

abstract:
  Traditional information retrieval systems rely on keywords to index documents
and queries. In such systems, documents are retrieved based on the number of
shared keywords with the query. This lexical-focused retrieval leads to
inaccurate and incomplete results when different keywords are used to describe
the documents and queries. Semantic-focused retrieval approaches attempt to
overcome this problem by relying on concepts rather than on keywords to
indexing and retrieval. The goal is to retrieve documents that are semantically
relevant to a given user query. This paper addresses this issue by proposing a
solution at the indexing level. More precisely, we propose a novel approach for
semantic indexing based on concepts identified from a linguistic resource. In
particular, our approach relies on the joint use of WordNet and WordNetDomains
lexical databases for concept identification. Furthermore, we propose a
semantic-based concept weighting scheme that relies on a novel definition of
concept centrality. The resulting system is evaluated on the TIME test
collection. Experimental results show the effectiveness of our proposition over
traditional IR approaches.


title: The color dependent morphology of the post-AGB star HD161796

abstract:
  Context. Many protoplanetary nebulae show strong asymmetries in their
surrounding shell, pointing to asymmetries during the mass loss phase.
Questions concerning the origin and the onset of deviations from spherical
symmetry are important for our understanding of the evolution of these objects.
Here we focus on the circumstellar shell of the post-AGB star HD 161796. Aims.
We aim at detecting signatures of an aspherical outflow, as well as to derive
the properties of it. Methods. We use the imaging polarimeter ExPo (the extreme
polarimeter), a visitor instrument at the William Herschel Telescope, to
accurately image the dust shell surrounding HD 161796 in various wavelength
filters. Imaging polarimetry allows us to separate the faint, polarized, light
from circumstellar material from the bright, unpolarized, light from the
central star. Results. The shell around HD 161796 is highly aspherical. A clear
signature of an equatorial density enhancement can be seen. This structure is
optically thick at short wavelengths and changes its appearance to optically
thin at longer wavelengths. In the classification of the two different
appearances of planetary nebulae from HST images it changes from being
classified as DUPLEX at short wavelengths to SOLE at longer wavelengths. This
strengthens the interpretation that these two appearances are manifestations of
the same physical structure. Furthermore, we find that the central star is
hotter than often assumed and the relatively high observed reddening is due to
circumstellar rather than interstellar extinction.


title: Hidden Symmetries and Geodesics of Kerr spacetime in Kaluza-Klein Theory

abstract:
  The Kerr spacetime in Kaluza-Klein theory describes a rotating black hole in
four dimensions from the Kaluza-Klein point of view and involves the signature
of an extra dimension that shows up through the appearance of the electric and
dilaton charges. In this paper, we study the separability properties of the
Hamilton-Jacobi equation for geodesics and the associated hidden symmetries in
the spacetime of the Kerr-Kaluza-Klein black hole. We show that the complete
separation of variables occurs only for massless geodesics, implying the
existence of hidden symmetries generated by a second rank conformal Killing
tensor. Employing a simple procedure built up on an "effective" metric, which
is conformally related to the original spacetime metric and admits a complete
separability structure, we construct the explicit expression for the conformal
Killing tensor. Next, we study the properties of the geodesic motion in the
equatorial plane, focusing on the cases of static and rotating Kaluza-Klein
black holes separately. In both cases, we obtain the defining equations for the
boundaries of the regions of existence, boundedness and stability of the
circular orbits as well as the analytical formulas for the orbital frequency,
the radial and vertical epicyclic frequencies of the geodesic motion.
Performing a detailed numerical analysis of these equations and frequencies, we
show that the physical effect of the extra dimension amounts to the significant
enlarging of the regions of existence, boundedness and stability towards the
event horizon, regardless of the classes of orbits.


title:
THz Magneto-electric atomic rotations in the chiral compound
  Ba$_3$NbFe$_3$Si$_2$O$_{14}$

abstract:
  We have determined the terahertz spectrum of the chiral langasite
Ba$_3$NbFe$_3$Si$_2$O$_{14}$ by means of synchrotron-radiation measurements.
Two excitations are revealed that are shown to have a different nature. The
first one, purely magnetic, is observed at low temperature in the magnetically
ordered phase and is assigned to a magnon. The second one persits far into the
paramagnetic phase and exhibits both an electric and a magnetic activity at
slightly different energies. This magnetoelectric excitation is interpreted in
terms of atomic rotations and requires a helical electric polarization.


title: Moment LMI approach to LTV impulsive control

abstract:
  In the 1960s, a moment approach to linear time varying (LTV) minimal norm
impulsive optimal control was developed, as an alternative to direct approaches
(based on discretization of the equations of motion and linear programming) or
indirect approaches (based on Pontryagin's maximum principle). This paper
revisits these classical results in the light of recent advances in convex
optimization, in particular the use of measures jointly with hierarchy of
linear matrix inequality (LMI) relaxations. Linearity of the dynamics allows us
to integrate system trajectories and to come up with a simplified LMI hierarchy
where the only unknowns are moments of a vector of control measures of time. In
particular, occupation measures of state and control variables do not appear in
this formulation. This is in stark contrast with LMI relaxations arising
usually in polynomial optimal control, where size grows quickly as a function
of the relaxation order. Jointly with the use of Chebyshev polynomials (as a
numerically more stable polynomial basis), this allows LMI relaxations of high
order (up to a few hundreds) to be solved numerically.


title: An Alexander-type duality for valuations

abstract:
  We prove an Alexander-type duality for valuations for certain subcomplexes in
the boundary of polyhedra. These strengthen and simplify results of Stanley
(1974) and Miller-Reiner (2005). We give a generalization of Brion's theorem
for this relative situation and we discuss the topology of the possible
subcomplexes for which the duality relation holds.


title:
Quasistatic adhesive contact of visco-elastic bodies and its numerical
  treatment for very small viscosity

abstract:
  An adhesive unilateral contact of elastic bodies with a small viscosity in
the linear Kelvin-Voigt rheology at small strains is scrutinized. The flow-rule
for debonding the adhesive is considered rate-independent and unidirectional,
and inertia is neglected. The asymptotics for the viscosity approaching zero
towards purely elastic material involves a certain defect-like measure
recording in some sense natural additional energy dissipated in the bulk due to
(vanishing) viscosity, which is demonstrated on particular 2-dimensional
computational simulations based on a semi-implicit time discretisation and a
spacial discretisation implemented by boundary-element method.


title: Electric charge catalysis by magnetic fields and a nontrivial holonomy

abstract:
  We describe a generic mechanism by which a system of Dirac fermions in
thermal equilibrium acquires electric charge in an external magnetic field. To
this end the fermions should have an additional quantum number, isospin or
color, and should be subject to a second magnetic field, which distinguishes
the isospin/color, as well as to a corresponding isospin chemical potential.
The role of the latter can be also played by a nontrivial holonomy (Polyakov
loop) along the Euclidean time direction. The charge is accumulated since the
degeneracies of occupied lowest Landau levels for particles of positive isospin
and anti-particles of negative isospin are different. We discuss two physical
systems, where this phenomenon can be realized. One is monolayer graphene,
where the isospin is associated with two valleys in the Brillouin zone and the
strain-induced pseudo-magnetic field acts differently on charge carriers in
different valleys. Another is hot QCD, for which the relevant non-Abelian field
configurations with both nonzero chromo-magnetic field and a nontrivial
Polyakov loop can be realized as calorons - topological solutions of Yang-Mills
equations at finite temperature. The induced electric charge on the caloron
field configuration is studied numerically. We argue that due to the
fluctuations of holonomy external magnetic field should tend to suppress charge
fluctuations in the quark-gluon plasma and estimate the importance of this
effect for off-central heavy-ion collisions.


title:
Controlled ripple texturing of suspended graphene membrane due to
  coupling with ultracold atoms

abstract:
  We discuss the possibility to create hybrid quantum systems that combine
ultracold atoms with graphene membranes. We investigate a setup in which a cold
atom cloud is placed close to a free-standing sheet of graphene at distances on
the order of a few hundred nanometers. The atoms then couple to the graphene
membrane via Casimir-Polder forces. Temporal changes in the atomic state of the
atomic cloud changes the Casimir-Polder interaction, thereby leading to the
creation of a backaction force in the graphene sheet. This setup provides a
controllable way to engineer ripples in a graphene sheet.


title: The hunt for old novae

abstract:
  We inform on the progress of our on-going project to identify and classify
old classical novae, using deep UBVR photometry and subsequent spectroscopy for
a proper candidate confirmation, and time-resolved observations in order to
find the orbital period and other physical properties of the identified old
novae. This way, we have already increased the number of confirmed southern and
equatorial post-novae from 33 to 50, and determined new orbital periods of
eight objects. As an example, we summarise the results on V728 Sco (Nova Sco
1862) which we found to be an eclipsing system with a 3.32 h orbital period,
displaying high and low states similar to dwarf-nova outbursts. Analysis of the
low-state eclipse indicates the presence of a small hot inner disc around the
white dwarf component.


title:
Nearby sources in the transition region between Galactic and
  Extragalactic cosmic rays

abstract:
  In this paper, a probable interpretation of a remarkable fine structure of
all particle spectra between the knee and the ankle, as well as a high content
of heavy nuclei around 10^17 eV measured recently in Tunka-133 and KASCADE
Grande experiments, is presented in the model where production of cosmic rays
in Type Ia SNRs provides observed cosmic rays (CR) flux around the knee.
Subtracting the contribution of these sources from all particle spectrum we
obtained the residual flux of CR in the transition region between Galactic and
Extragalactic CR in the range 10^17-5 10^18 eV. The obtained spectrum also has
a pronounced knee at energy (2-3)10^17 eV and slopes g1 ~ 1.8+-0.3 below it and
g2 ~3.4 above it. We analyzed the possible contribution from known Galactic
sources and found that formally the best candidate to contribute significantly
to the transition region is Cas A. This source posses a number of unusual
properties and considered as Type IIb SNR. However we showed that the
hypothesis of extragalactic origin of CR starting from 10^17 eV seems more
realistic.


title: Hyperbolic Alexandrov-Fenchel quermassintegral inequalities I

abstract:
  In this paper we prove the following geometric inequality in the hyperbolic
space $\H^n$ ($n\ge 5)$, which is a hyperbolic Alexandrov-Fenchel inequality,
\[\begin{array}{rcl} \ds \int_\Sigma \s_4 d \mu\ge \ds\vs
C_{n-1}^4\omega_{n-1}\left\{\left(\frac{|\Sigma|}{\omega_{n-1}} \right)^\frac
12 + \left(\frac{|\Sigma|}{\omega_{n-1}} \right)^{\frac 12\frac {n-5}{n-1}}
\right\}^2, \end{array}\] provided that $\Sigma$ is a horospherical convex
hypersurface. Equality holds if and only if $\Sigma$ is a geodesic sphere in
$\H^n$.


title:
The coupling between internal waves and shear-induced turbulence in
  stellar radiation zones: the critical layer

abstract:
  Internal gravity waves (hereafter IGWs) are known as one of the candidates
for explaining the angular velocity profile in the Sun and in solar-type
main-sequence and evolved stars, due to their role in the transport of angular
momentum. Our bringing concerns critical layers, a process poorly explored in
stellar physics, defined as the location where the local relative frequency of
a given wave to the rotational frequency of the fluid tends to zero (i.e that
corresponds to co-rotation resonances). IGW propagate through stably-stratified
radiative regions, where they extract or deposit angular momentum through two
processes: radiative and viscous dampings and critical layers. Our goal is to
obtain a complete picture of the effects of this latters. First, we expose a
mathematical resolution of the equation of propagation for IGWs in adiabatic
and non-adiabatic cases near critical layers. Then, the use of a dynamical
stellar evolution code, which treats the secular transport of angular momentum,
allows us to apply these results to the case of a solar-like star.The analysis
reveals two cases depending on the value of the Richardson number at critical
layers: a stable one, where IGWs are attenuated as they pass through a critical
level, and an unstable turbulent case where they can be reflected/transmitted
by the critical level with a coefficient larger than one. Such
over-reflection/transmission can have strong implications on our vision of
angular momentum transport in stellar interiors. This paper highlights the
existence of two regimes defining the interaction between an IGW and a critical
layer. An application exposes the effect of the first regime, showing a
strengthening of the damping of the wave. Moreover, this work opens new ways
concerning the coupling between IGWs and shear instabilities in stellar
interiors.


title: Static and dynamic semantics of NoSQL languages

abstract:
  We present a calculus for processing semistructured data that spans
differences of application area among several novel query languages, broadly
categorized as "NoSQL". This calculus lets users define their own operators,
capturing a wider range of data processing capabilities, whilst providing a
typing precision so far typical only of primitive hard-coded operators. The
type inference algorithm is based on semantic type checking, resulting in type
information that is both precise, and flexible enough to handle structured and
semistructured data. We illustrate the use of this calculus by encoding a large
fragment of Jaql, including operations and iterators over JSON, embedded SQL
expressions, and co-grouping, and show how the encoding directly yields a
typing discipline for Jaql as it is, namely without the addition of any type
definition or type annotation in the code.


title:
Oracle Pushdown Automata, Nondeterministic Reducibilities, and the CFL
  Hierarchy over the Family of Context-Free Languages

abstract:
  To expand a fundamental theory of context-free languages, we equip
nondeterministic one-way pushdown automata with additional oracle mechanisms,
which naturally induce various nondeterministic reducibilities among formal
languages. As a natural restriction of NP-reducibility, we introduce a notion
of many-one CFL reducibility and conduct a ground work to formulate a coherent
framework for further expositions. Two more powerful reducibilities--bounded
truth-table and Turing CFL-reducibilities--are also discussed in comparison.
The Turing CFL-reducibility, in particular, helps us introduce an exquisite
hierarchy, called the CFL hierarchy, built over the family CFL of context-free
languages. For each level of this hierarchy, its basic structural properties
are proven and three alternative characterizations are presented. The second
level is not included in NC(2) unless NP= NC(2). The first and second levels of
the hierarchy are different. The rest of the hierarchy (more strongly, the
Boolean hierarchy built over each level of the hierarchy) is also infinite
unless the polynomial hierarchy over NP collapses. This follows from a
characterization of the Boolean hierarchy over the k-th level of the polynomial
hierarchy in terms of the Boolean hierarchy over the k+1st level of the CFL
hierarchy using log-space many-one reductions. Similarly, the complexity class
Theta(k) is related to the closure of the k-th level of the CFL hierarchy under
log-space truth-table reductions. We also argue that the CFL hierarchy
coincides with a hierarchy over CFL built by application of many-one
CFL-reductions. We show that BPCFL--a bounded-error probabilistic version of
CFL--is not included in CFL even in the presence of advice. Employing a known
circuit lower bound and a switching lemma, we exhibit a relativized world where
BPCFL is not located within the second level of the CFL hierarchy.


title: Spinless Quantum Field Theory and Interpretation

abstract:
  Quantum field theory is mostly known as the most advanced and well-developed
theory in physics, which combines quantum mechanics and special relativity
consistently. In this work, we study the spinless quantum field theory, namely
the Klein-Gordon equation, and we find that there exists a Dirac form of this
equation which predicts the existence of spinless fermion. For its
understanding, we start from the interpretation of quantum field based on the
concept of quantum scope, we also extract new meanings of wave-particle duality
and quantum statistics. The existence of spinless fermion is consistent with
spin-statistics theorem and also supersymmetry, and it leads to several new
kinds of interactions among elementary particles. Our work contributes to the
study of spinless quantum field theory and could have implications for the case
of higher spin.


title:
Efficient Compressive Sampling of Spatially Sparse Fields in Wireless
  Sensor Networks

abstract:
  Wireless sensor networks (WSN), i.e. networks of autonomous, wireless sensing
nodes spatially deployed over a geographical area, are often faced with
acquisition of spatially sparse fields. In this paper, we present a novel
bandwidth/energy efficient CS scheme for acquisition of spatially sparse fields
in a WSN. The paper contribution is twofold. Firstly, we introduce a sparse,
structured CS matrix and we analytically show that it allows accurate
reconstruction of bidimensional spatially sparse signals, such as those
occurring in several surveillance application. Secondly, we analytically
evaluate the energy and bandwidth consumption of our CS scheme when it is
applied to data acquisition in a WSN. Numerical results demonstrate that our CS
scheme achieves significant energy and bandwidth savings wrt state-of-the-art
approaches when employed for sensing a spatially sparse field by means of a
WSN.


title:
Explicit Infinity-Harmonic Maps whose Interfaces have Junctions and
  Corners

abstract:
  Given a map $u : \Om \sub \R^n \larrow \R^N$, the $\infty$-Laplacian is the
system \[ \label{1} \De_\infty u \, :=\, \Big(Du \ot Du + |Du|^2 [Du]^\bot \
\ot I \Big) : D^2 u\, = \, 0 \tag{1} \] and arises as the "Euler-Lagrange PDE"
of the supremal functional $E_\infty(u,\Om)= \|Du\|_{L^\infty(\Om)}.$ \eqref{1}
is the model PDE of vector-valued Calculus of Variations in $L^\infty$ and
first appeared in the author's recent work \cite{K1,K2,K3}. Solutions to
\eqref{1} present a natural phase separation with qualitatively different
behaviour on each phase. Moreover, on the interfaces the coefficients of
\eqref{1} are discontinuous. Herein we constuct new explicit smooth solutions
for $n=N=2$ for which the interfaces have triple junctions and nonsmooth
corners. The high complexity of these solutions provides further understanding
of the PDE \eqref{1} and shows there can be no regularity theory of interfaces.


title: A characterization of the Radon-Nikodym property

abstract:
  It is well known that every bounded below and non increasing sequence in the
real line converges. We give a version of this result valid in Banach spaces
with the Radon-Nikodym property, thus extending a former result of A.
Proch\'azka.


title:
Optimal bispectrum estimator and simulations of the the CMB Lensing-ISW
  non-Gaussian signal

abstract:
  In this paper we present the tools to optimally extract the
Lensing-Integrated Sachs Wolfe (L-ISW) bispectrum signal from future CMB data.
We implement two different methods to simulate the non-Gaussian CMB maps with
the L-ISW signal: a non-perturbative method based on the FLINTS lensing code
and the separable mode expansion method. We implement the Komatsu, Spergel and
Wandelt (KSW) optimal estimator analysis for the Lensing-ISW bispectrum and we
test it on the non-Gaussian simulations in the case of a realistic CMB
experimental settings with an inhomogeneous sky coverage. We show that the
estimator approaches the Cramer-Rao bound and that Wiener filtering the L-ISW
simulations gives a slight improvement on the estimate of $f_{NL}^{L-ISW}$ of
$\leq 10%$. For a realistic CMB experimental setting accounting for anisotropic
noise and masked sky, we show that the linear term of the estimator is highly
correlated to the cubic term and it is necessary to recover the signal and the
optimal error bars. We also show that the L-ISW bispectrum, if not correctly
accounted for, yields an underestimation of the $f_{NL}^{local}$ error bars of
$\simeq 4%$. A joint analysis of the non-Gaussian shapes and/or L-ISW template
subtraction is needed in order to recover unbiased results of the primordial
non-Gaussian signal from ongoing and future CMB experiments.


title: Modeling the large-scale structure of a barchan dune field

abstract:
  In nature, barchan dunes typically exist as members of larger fields that
display striking, enigmatic structures that cannot be readily explained by
examining the dynamics at the scale of single dunes, or by appealing to
patterns in external forcing. To explore the possibility that observed
structures emerge spontaneously as a collective result of many dunes
interacting with each other, we built a numerical model that treats barchans as
discrete entities that interact with one another according to simplified rules
derived from theoretical and numerical work and from field observations: (1)
Dunes exchange sand through the fluxes that leak from the downwind side of each
dune and are captured on their upstream sides; (2) when dunes become
sufficiently large, small dunes are born on their downwind sides (`calving');
and (3) when dunes collide directly enough, they merge. Results show that these
relatively simple interactions provide potential explanations for a range of
field-scale phenomena including isolated patches of dunes and heterogeneous
arrangements of similarly sized dunes in denser fields. The results also
suggest that (1) dune field characteristics depend on the sand flux fed into
the upwind boundary, although (2) moving downwind, the system approaches a
common attracting state in which the memory of the upwind conditions vanishes.
This work supports the hypothesis that calving exerts a first-order control on
field-scale phenomena; it prevents individual dunes from growing without bound,
as single-dune analyses suggest, and allows the formation of roughly realistic,
persistent dune field patterns.


title:
Automated Identification and Classification of Stereochemistry:
  Chirality and Double Bond Stereoisomerism

abstract:
  Stereoisomers have the same molecular formula and the same atom connectivity
and their existence can be related to the presence of different
three-dimensional arrangements. Stereoisomerism is of great importance in many
different fields since the molecular properties and biological effects of the
stereoisomers are often significantly different. Most drugs for example, are
often composed of a single stereoisomer of a compound, and while one of them
may have therapeutic effects on the body, another may be toxic. A challenging
task is the automatic detection of stereoisomers using line input
specifications such as SMILES or InChI since it requires information about
group theory (to distinguish stereoisomers using mathematical information about
its symmetry), topology and geometry of the molecule. There are several
software packages that include modules to handle stereochemistry, especially
the ones to name a chemical structure and/or view, edit and generate chemical
structure diagrams. However, there is a lack of software capable of
automatically analyzing a molecule represented as a graph and generate a
classification of the type of isomerism present in a given atom or bond.
Considering the importance of stereoisomerism when comparing chemical
structures, this report describes a computer program for analyzing and
processing steric information contained in a chemical structure represented as
a molecular graph and providing as output a binary classification of the isomer
type based on the recommended conventions. Due to the complexity of the
underlying issue, specification of stereochemical information is currently
limited to explicit stereochemistry and to the two most common types of
stereochemistry caused by asymmetry around carbon atoms: chiral atom and double
bond. A Webtool to automatically identify and classify stereochemistry is
available at http://nams.lasige.di.fc.ul.pt/tools.php


title:
Exact Conditional and Unconditional Cram\`er-Rao Bounds for Near Field
  Localization

abstract:
  This paper considers the Cram\`er-Rao lower Bound (CRB) for the source
localization problem in the near field. More specifically, we use the exact
expression of the delay parameter for the CRB derivation and show how this
exact CRB can be significantly different from the one given in the literature
and based on an approximate time delay expression (usually considered in the
Fresnel region). This CRB derivation is then generalized by considering the
exact expression of the received power profile (i.e., variable gain case)
which, to our best knowledge, has been ignored in the literature. Finally, we
exploit the CRB expression to introduce the new concept of Near Field
Localization (NFL) region for a target localization performance associated to
the application at hand. We illustrate the usefulness of the proposed CRB
derivation and its developments as well as the NFL region concept through
numerical simulations in different scenarios.


title: The carbon-to-oxygen ratio in stars with planets

abstract:
  In some recent works, the C/O abundance ratio in high-metallicity stars with
planets is found to vary from 0.4 to about 1.0. This has led to discussions
about the existence of terrestrial planets with a carbon-dominated composition
that is very different from the composition of the Earth. The C/O values were
obtained by determining carbon abundances from high-excitation CI lines and
oxygen abundances from the forbidden [OI] line at 6300 A. This weak line is,
however, strongly affected by a nickel blend at high metallicities. Aiming for
more precise C/O ratios, oxygen abundances in this paper are derived from the
high-excitation OI triplet at 7774 A and carbon abundances from the CI lines at
5052 and 5380 A using MARCS model atmospheres and including non-LTE
corrections. The results do not confirm the high C/O ratios previously found.
C/O shows a tight, slightly increasing dependence on metallicity from C/O=0.58
at [Fe/H]=0.0 to C/O=0.70 at [Fe/H] =0.4 with an rms scatter of only 0.06.
Assuming that the composition of a proto-planetary disk is the same as that of
the host star, the C/O values found in this paper lend no support to the
existence of carbon-rich planets. The small scatter of C/O among thin-disk
stars suggests that the nucleosynthesis products of Type II supernovae and low-
to intermediate-mass stars are well mixed in the interstellar medium.


title: A dark matter scaling relation from mirror dark matter

abstract:
  Mirror dark matter, and other similar dissipative dark matter candidates,
need an energy source to stabilize dark matter halos in spiral galaxies. It has
been suggested previously that ordinary supernovae can potentially supply the
required energy. By matching the energy supplied to the halo from supernovae to
that lost due to radiative cooling, we here derive a rough scaling relation,
$R_{SN} \propto \rho_0 r_0^2$ ($R_{SN}$ is the supernova rate and $\rho_0, \
r_0$ the dark matter central density and core radius). Such a relation is
consistent with dark matter properties inferred from studies of spiral galaxies
with halo masses larger than $3\times 10^{11} M_\odot$. We speculate that other
observed galaxy regularities might be explained within the framework of such
dissipative dark matter.


title: A Digital Automatic Sliding Door with a Room Light Control System

abstract:
  Automatic door is an automated movable barrier installed in the entry of a
room or building to restrict access, provide ease of opening a door or provide
visual privacy. As a result of enhanced civilization and modernization, the
human nature demands more comfort to his life. The man seeks ways to do things
easily and which saves time. So thus, the automatic gates are one of the
examples that human nature invent to bring comfort and ease in its daily life.
To this end, we model and design an automatic sliding door with a room light
control system to provide the mentioned needs. This was achieved by considering
some factors such as economy, availability of components and research
materials, efficiency, compatibility and portability and also durability in the
design process. The performance of the system after test met design
specifications. This system works on the principle of breaking an infrared beam
of light, sensed by a photodiode. It consists of two transmitting infrared
diodes and two receiving photo-diodes. The first one is for someone coming in
and the second one is for someone going out of the room. The photodiodes are
connected to comparators, which give a lower output when the beam is broken and
high output when transmitting normally. The general operation of the work and
performance is dependent on the presence of an intruder entering through the
door and how close he/she is in closer to the door. The door is meant to open
automatically but in a case where there is no power supply trying to force the
door open would damage the mechanical control system of the unit. The overall
work was implemented with a constructed work, tested working and perfectly
functional.


title:
Principal Poincar\'e Pontryagin Function associated to some families of
  Morse real polynomials

abstract:
  It is known that the Principal Poincar\'e Pontryagin Function is generically
an Abelian integral. We give a sufficient condition on monodromy to ensure that
it is an Abelian integral also in non generic cases. In non generic cases it is
an iterated integral. Uribe [17, 18] gives in a special case a precise
description of the Principal Poincar\'e Pontryagin Function, an iterated
integral of length at most 2, involving logarithmic functions with only one
ramification at a point at infinity. We extend this result to some non
isodromic families of real Morse polynomials.


title:
Abundances of neutron-capture elements in stars of the galactic disk
  substructures

abstract:
  The aim of this work is to present and discuss the observations of the iron
peak (Fe, Ni) and neutron-capture element (Y, Zr, Ba, La, Ce, Nd, Sm, and Eu)
abundances for 276 FGK dwarfs, located in the galactic disk with metallicity -1
< [Fe/H] < +0.3. Atmospheric parameters and chemical composition of the studied
stars were determined from an high resolution, high signal-to-noise echelle
spectra obtained with the echelle spectrograph ELODIE at the Observatoire de
Haute-Provence (France). Effective temperatures were estimated by the line
depth ratio method and from the H_{\alpha} line-wing fitting. Surface gravities
(log g) were determined by parallaxes and the ionization balance of iron.
Abundance determinations were carried out using the LTE approach, taking the
hyperfine structure for Eu into account, and the abundance of Ba was computed
under the NLTE approximation. We are able to assign most of the stars in our
sample to the substructures of the Galaxy thick disk, thin disk, or Hercules
stream according to their kinematics. The classification of 27 stars is
uncertain. For most of the stars in the sample, the abundances of
neutron-capture elements have not been measured earlier. For all of them, we
provide the chemical composition and discuss the contribution from different
nucleosynthesis processes.


title:
On a dislocation density based two-phase plasticity model: refinement
  and extension to non-proportional loading

abstract:
  The two-phase composite approach of Estrin et al. (1998) describes an
evolving dislocation cell structure. Mckenzie et al. (2007) enhanced the model
to capture the effects of hydrostatic pressure and temperature during severe
plastic deformation. The goal of the present study is to incorporate this
microstructural model into the macroscopic viscoplasticity framework proposed
by Shutov and Krei\ss ig (2008a). Thereby, the two-phase composite approach is
examined carefully. Both physical and numerical drawbacks are revealed and
possible solutions are presented, thus leading to a refined micro model.
Moreover, some improvements concerning reliable parameter identification are
suggested as well. The material parameters of the refined micro model are
identified for an aluminum alloy using TEM cell size measurements. Then, an
extension to non-proportional deformation is performed in such a way that the
evolution of dislocation densities becomes sensitive to load path changes.
Experimental findings suggest that such deformation modes can significantly
influence the evolution of microstructure, including the dissolution of cells
and the reduction of total dislocation density shortly after the load path
change. In order to capture such effects, some tensor-valued state variables
are introduced which couple the refined micro model with the macroscopic
viscoplasticity model. As a result, a new system of constitutive equations is
obtained. In order to demonstrate its capability to respond to load path
changes, load cases as typical for Equal Channel Angular Pressing (ECAP) are
considered. The obtained evolution of dislocation populations differs
signficantly depending on which ECAP route is applied.


title: Design and Development of an Ultrasonic Motion Detector

abstract:
  The ultrasonic motion detector devices emit ultrasonic sound energy into an
area of interest (monitored area), and this further reacts to a change in the
reflected energy pattern. The system uses a technique that is based on a
frequency shift in reflected energy to detect a movement or change in position
(motion). In this system, ultrasonic sound is transmitted from the transmitting
device which is normally in the form of energy. The transmitted sound utilizes
air as its medium and this travel in a wave type motion. The wave is reflected
back from the surroundings in the room/hallway and the device hears a pitch
characteristic of the protected environment. In this system, the wave pattern
is disturbed and reflected back more quickly, thus increasing the pitch and
signaling an alarm whenever motion is detected. The main contribution of this
work is the design of a circuit that can sense motion through movement of
anything, a low cost and portable motion detector, and the design of a circuit
that can be used to trigger another circuit whether to ON or OFF depending on
the circuit attached to it. Generally, the design is made to detect movement or
moving object in a an enclosed area. In this work, a transmitter transducer
generates a signal at a frequency of 40khz, and when the signal is blocked by
any moving object, and this in turn, triggers a buzzer via a timing circuit.
This system works on the principle of the signal interference by a moving body,
and the system is dependent on the presence of an intruder or moving object
within a monitored area. The system after design and construction was tested
and found to work in accordance with specifications.


title:
Multi-relational Learning Using Weighted Tensor Decomposition with
  Modular Loss

abstract:
  We propose a modular framework for multi-relational learning via tensor
decomposition. In our learning setting, the training data contains multiple
types of relationships among a set of objects, which we represent by a sparse
three-mode tensor. The goal is to predict the values of the missing entries. To
do so, we model each relationship as a function of a linear combination of
latent factors. We learn this latent representation by computing a low-rank
tensor decomposition, using quasi-Newton optimization of a weighted objective
function. Sparsity in the observed data is captured by the weighted objective,
leading to improved accuracy when training data is limited. Exploiting sparsity
also improves efficiency, potentially up to an order of magnitude over
unweighted approaches. In addition, our framework accommodates arbitrary
combinations of smooth, task-specific loss functions, making it better suited
for learning different types of relations. For the typical cases of real-valued
functions and binary relations, we propose several loss functions and derive
the associated parameter gradients. We evaluate our method on synthetic and
real data, showing significant improvements in both accuracy and scalability
over related factorization techniques.


title:
An electronic digital combination lock: A precise and reliable security
  system

abstract:
  The increasing rate of crime, attacks by thieves, intruders and vandals,
despite all forms of security gadgets and locks still need the attention of
researchers to find a permanent solution to the well being of lives and
properties of individuals. To this end, we design a cheap and effective
security system for buildings, cars, safes, doors and gates, so as to prevent
unauthorized person from having access to ones properties through the use of
codes, we therefore experiment the application of electronic devices as locks.
However, a modular approach was employed in the design in which the combination
lock was divided into units and each unit designed separately before being
coupled to form a whole functional system. During the design, we conducted
Twenty tests with the first eight combinations being four in number, the next
seven tests being five and the last five combinations being six. This was done
because of the incorporation of 2 dummy switches in the combinations. From the
result obtained, combinations 8, 11, 13 gave the correct output combination.
However, 8 being the actual combination gave the required output. The general
operation of the system and performance is dependent on the key combinations.
The overall system was constructed and tested and it works perfectly.


title: Fibre bundle formulation of time-dependent mechanics

abstract:
  We address classical and quantum mechanics in a general setting of arbitrary
time-dependent transformations. Classical non-relativistic mechanics is
formulated as a particular field theory on smooth fibre bundles over a time
axis. Connections on these bundles describe reference frames. Quantum
time-dependent mechanics is phrased in geometric terms of Banach and Hilbert
bundles and connections on these bundles. A quantization scheme speaking this
language is leafwise geometric quantization.


title: Quasistatic Droplet percolation

abstract:
  We consider the Hele-Shaw problem in a randomly perforated domain with zero
Neumann boundary conditions. A homogenization limit is obtained as the
characteristic scale of the domain goes to zero. Specifically, we prove that
the solutions as well as their free boundaries converge uniformly to those
corresponding to a homogeneous and anisotropic Hele-Shaw problem set in
$\mathbb{R}^d$. The main challenge when deriving a limit lies in controlling
the oscillations of the free boundary, this is overcome first by extending De
Giorgi-Nash-Moser type estimates to perforated domains and second by proving
the almost surely non-degenerate growth of the solution near its free boundary.


title: Observation of the decay $B_c^+ \to \psi(2S)\pi^+$

abstract:
  The decay $B_c^+ \to \psi(2S)\pi^+$ with $\psi(2S) \to \mu^+\mu^-$ is
observed with a significance of $5.2\,\sigma$ using $pp$ collision data
corresponding to an integrated luminosity of $1.0\,\invfb$ collected by the
LHCb experiment. The branching fraction of $B_c^+ \to \psi(2S)\pi^+$ decays
relative to that of the $B_c^+ \to J/\psi\pi^+$ mode is measured to be
\begin{equation*} \frac{\mathcal{B}(B_c^+ \to \psi(2S)\pi^+)}{\mathcal{B}(B_c^+
\to J/\psi\pi^+)} = 0.250 \pm 0.068 \,\text{stat} \pm 0.014 \,\text{\syst} \pm
0.006 \,(\mathcal{B}). \end{equation*} The last term is the uncertainty on the
ratio $\mathcal{B}(\psi(2S) \to \mu^+\mu^-)/\mathcal{B}(J/\psi \to
\mu^+\mu^-)$.


title:
Mixing local and global information for community detection in large
  networks

abstract:
  The problem of clustering large complex networks plays a key role in several
scientific fields ranging from Biology to Sociology and Computer Science. Many
approaches to clustering complex networks are based on the idea of maximizing a
network modularity function. Some of these approaches can be classified as
global because they exploit knowledge about the whole network topology to find
clusters. Other approaches, instead, can be interpreted as local because they
require only a partial knowledge of the network topology, e.g., the neighbors
of a vertex. Global approaches are able to achieve high values of modularity
but they do not scale well on large networks and, therefore, they cannot be
applied to analyze on-line social networks like Facebook or YouTube. In
contrast, local approaches are fast and scale up to large, real-life networks,
at the cost of poorer results than those achieved by local methods. In this
article we propose a glocal method to maximizing modularity, i.e., our method
uses information at the global level, yet its scalability on large networks is
comparable to that of local methods. The proposed method is called COmplex
Network CLUster DEtection (or, shortly, CONCLUDE.) It works in two stages: in
the first stage it uses an information-propagation model, based on random and
non-backtracking walks of finite length, to compute the importance of each edge
in keeping the network connected (called edge centrality.) Then, edge
centrality is used to map network vertices onto points of an Euclidean space
and to compute distances between all pairs of connected vertices. In the second
stage, CONCLUDE uses the distances computed in the first stage to partition the
network into clusters. CONCLUDE is computationally efficient since in the
average case its cost is roughly linear in the number of edges of the network.


title:
Simulation of electron transport in electron beam induced deposition of
  nanostructures

abstract:
  We present a numerical investigation of energy and charge distributions
during electron-beam-induced growth of W nanostructures on SiO2 substrates
using Monte Carlo simulation of electron transport. This study gives a
quantitative insight into the deposition of energy and charge in the substrate
and in already existing metallic nanostructures in the presence of the electron
beam. We analyze electron trajectories, inelastic mean free paths, and
distribution of backscattered electrons in different deposit compositions and
depths. We find that, while in the early stages of the nanostructure growth a
significant fraction of electron trajectories still interact with the
substrate, as the nanostructure becomes thicker the transport takes place
almost exclusively in the nanostructure. In particular, a larger deposit
density leads to enhanced electron backscattering. This work shows how
mesoscopic radiation-transport techniques can contribute to a model which
addresses the multi-scale nature of the electron-beam-induced deposition (EBID)
process. Furthermore, similar simulations can aid in understanding the role
played by backscattered electrons and emitted secondary electrons in the change
of structural properties of nanostructured materials during post-growth
electron-beam treatments.


title:
Maximum Possibility Of Spectrum Access In Cognitive Radio Using Fuzzy
  Logic System

abstract:
  Many spectrum methods have been proposed to use spectrum effectively, the
opportunistic spectrum access has become the most viable approach to achieve
near-optimal spectrum utilization by allowing secondary users to sense and
access available spectrum opportunistically. However, a naive spectrum access
for secondary users can make spectrum utilization inefficient and increase
interference to adjacent users. In this paper, we propose a novel approach
using Fuzzy Logic System (FLS) to control the spectrum access. We have to
minimize the call blocking and interference. The linguistic knowledge of
spectrum access are based on three descriptors namely spectrum utilization
efficiency of the secondary user, its degree of mobility, and its distance to
the primary user. The spectrum is chosen for accessing based on the maximum
possibility for better utilization of the spectrum


title: Enhancing community detection using a network weighting strategy

abstract:
  A community within a network is a group of vertices densely connected to each
other but less connected to the vertices outside. The problem of detecting
communities in large networks plays a key role in a wide range of research
areas, e.g. Computer Science, Biology and Sociology. Most of the existing
algorithms to find communities count on the topological features of the network
and often do not scale well on large, real-life instances.
  In this article we propose a strategy to enhance existing community detection
algorithms by adding a pre-processing step in which edges are weighted
according to their centrality w.r.t. the network topology. In our approach, the
centrality of an edge reflects its contribute to making arbitrary graph
tranversals, i.e., spreading messages over the network, as short as possible.
Our strategy is able to effectively complements information about network
topology and it can be used as an additional tool to enhance community
detection. The computation of edge centralities is carried out by performing
multiple random walks of bounded length on the network. Our method makes the
computation of edge centralities feasible also on large-scale networks. It has
been tested in conjunction with three state-of-the-art community detection
algorithms, namely the Louvain method, COPRA and OSLOM. Experimental results
show that our method raises the accuracy of existing algorithms both on
synthetic and real-life datasets.


title:
The Low-Luminosity End of the Radius-Luminosity Relationship for Active
  Galactic Nuclei

abstract:
  We present an updated and revised analysis of the relationship between the
Hbeta broad-line region (BLR) radius and the luminosity of the active galactic
nucleus (AGN). Specifically, we have carried out two-dimensional surface
brightness decompositions of the host galaxies of 9 new AGNs imaged with the
Hubble Space Telescope Wide Field Camera 3. The surface brightness
decompositions allow us to create "AGN-free" images of the galaxies, from which
we measure the starlight contribution to the optical luminosity measured
through the ground-based spectroscopic aperture. We also incorporate 20 new
reverberation-mapping measurements of the Hbeta time lag, which is assumed to
yield the average Hbeta BLR radius. The final sample includes 41 AGNs covering
four orders of magnitude in luminosity. The additions and updates incorporated
here primarily affect the low-luminosity end of the R-L relationship. The best
fit to the relationship using a Bayesian analysis finds a slope of alpha =
0.533 (+0.035/-0.033), consistent with previous work and with simple
photoionization arguments. Only two AGNs appear to be outliers from the
relationship, but both of them have monitoring light curves that raise doubt
regarding the accuracy of their reported time lags. The scatter around the
relationship is found to be 0.19(+/-0.02) dex, but would be decreased to 0.13
dex by the removal of these two suspect measurements. A large fraction of the
remaining scatter in the relationship is likely due to the inaccurate distances
to the AGN host galaxies. Our results help support the possibility that the R-L
relationship could potentially be used to turn the BLRs of AGNs into
standardizable candles. This would allow the cosmological expansion of the
Universe to be probed by a separate population of objects, and over a larger
range of redshifts.


title:
Statistical estimation of quadratic R\'enyi entropy for a stationary
  m-dependent sequence

abstract:
  The R\'enyi entropy is a generalization of the Shannon entropy and is widely
used in mathematical statistics and applied sciences for quantifying the
uncertainty in a probability distribution. We consider estimation of the
quadratic R\'enyi entropy and related functionals for the marginal distribution
of a stationary m-dependent sequence. The U-statistic estimators under study
are based on the number of epsilon-close vector observations in the
corresponding sample. A variety of asymptotic properties for these estimators
are obtained (e.g., consistency, asymptotic normality, Poisson convergence).
The results can be used in diverse statistical and computer science problems
whenever the conventional independence assumption is too strong (e.g.,
epsilon-keys in time series databases, distribution identification problems for
dependent samples).


title: Reactive trajectories and the transition path process

abstract:
  We study the trajectories of a solution $X_t$ to an It\^o stochastic
differential equation in $\Rm^d$, as the process passes between two disjoint
open sets, $A$ and $B$. These segments of the trajectory are called transition
paths or reactive trajectories, and they are of interest in the study of
chemical reactions and thermally activated processes. In that context, the sets
$A$ and $B$ represent reactant and product states. Our main results describe
the probability law of these transition paths in terms of a transition path
process $Y_t$, which is a strong solution to an auxiliary SDE having a singular
drift term. We also show that statistics of the transition path process may be
recovered by empirical sampling of the original process $X_t$. As an
application of these ideas, we prove various representation formulas for
statistics of the transition paths. We also identify the density and current of
transition paths. Our results fit into the framework of the transition path
theory by E and Vanden-Eijnden.


title: Designing short robust NOT gates for quantum computation

abstract:
  Composite pulses, originally developed in Nuclear Magnetic Resonance (NMR),
have found widespread use in experimental quantum information processing (QIP)
to reduce the effects of systematic errors. Most pulses used so far have simply
been adapted from existing NMR designs, and while techniques have been
developed for designing composite pulses with arbitrary precision the results
have been quite complicated and have found little application. Here I describe
techniques for designing short but effective composite pulses to implement
robust NOT gates, bringing together existing insights from NMR and QIP, and
present some novel composite pulses.


title: Exponential mapping in Euler's elastic problem

abstract:
  The classical Euler's problem on optimal configurations of elastic rod in the
plane with fixed endpoints and tangents at the endpoints is considered. The
global structure of the exponential mapping that parameterises extremal
trajectories is described. It is proved that open domains cut out by Maxwell
strata in the preimage and image of the exponential mapping are mapped
diffeomorphically. As a consequence, computation of globally optimal elasticae
with given boundary conditions is reduced to solving systems of algebraic
equations having unique solutions in the open domains. For certain special
boundary conditions, optimal elasticae are presented.


title: A Novel Measure of Edge Centrality in Social Networks

abstract:
  The problem of assigning centrality values to nodes and edges in graphs has
been widely investigated during last years. Recently, a novel measure of node
centrality has been proposed, called k-path centrality index, which is based on
the propagation of messages inside a network along paths consisting of at most
k edges. On the other hand, the importance of computing the centrality of edges
has been put into evidence since 1970's by Anthonisse and, subsequently by
Girvan and Newman. In this work we propose the generalization of the concept of
k-path centrality by defining the k-path edge centrality, a measure of
centrality introduced to compute the importance of edges. We provide an
efficient algorithm, running in O(k m), being m the number of edges in the
graph. Thus, our technique is feasible for large scale network analysis.
Finally, the performance of our algorithm is analyzed, discussing the results
obtained against large online social network datasets.


title:
Mixed Maps for Kolmogoroff-Nagumo-Type Averaging on the Compact Stiefel
  Manifold

abstract:
  The present research work proposes a new fast fixed-point averaging algorithm
on the compact Stiefel manifold based on a mixed retraction/lifting pair.
Numerical comparisons between fixed-point algorithms based on the proposed
non-associated retraction/lifting map pair and two associated
retraction/lifting pairs confirm that the averaging algorithm based on a
combination of mixed maps is remarkably less computationally demanding than the
same averaging algorithm based on any of the constituent associated
retraction/lifting pairs.


title: Simplifying Energy Optimization using Partial Enumeration

abstract:
  Energies with high-order non-submodular interactions have been shown to be
very useful in vision due to their high modeling power. Optimization of such
energies, however, is generally NP-hard. A naive approach that works for small
problem instances is exhaustive search, that is, enumeration of all possible
labelings of the underlying graph. We propose a general minimization approach
for large graphs based on enumeration of labelings of certain small patches.
This partial enumeration technique reduces complex high-order energy
formulations to pairwise Constraint Satisfaction Problems with unary costs
(uCSP), which can be efficiently solved using standard methods like TRW-S. Our
approach outperforms a number of existing state-of-the-art algorithms on well
known difficult problems (e.g. curvature regularization, stereo,
deconvolution); it gives near global minimum and better speed.
  Our main application of interest is curvature regularization. In the context
of segmentation, our partial enumeration technique allows to evaluate curvature
directly on small patches using a novel integral geometry approach.


title: On Schoen surfaces

abstract:
  We give a new construction of the irregular, generalized Lagrangian, surfaces
of general type with p_g=5, \chi=2, K^2=8, recently discovered by Chad Schoen.
Our approach proves that, if S is a general Schoen surface, its canonical map
is a finite morphism of degree 2 onto a canonical surface with invariants
p_g=5, \chi=6, K^2=8, a complete intersection of a quadric and a quartic
hypersurface in P^4, with 40 even nodes.


title: Three Layer Hierarchical Model for Chord

abstract:
  Increasing popularity of decentralized P2P architecture emphasizes on the
need to come across an overlay structure that can provide efficient content
discovery mechanism, accommodate high churn rate and adapt to failures.
Traditional p2p systems are not able to solve the problems relating scalability
and high churn rates. Hierarchical model were introduced to provide better
fault isolation, effective bandwidth utilization, a superior adaptation to the
underlying physical network and a reduction of the lookup path length as
additional advantages. It is more efficient and easier to manage than
traditional p2p networks. This paper discusses a further step in p2p hierarchy
via 3-layers hierarchical model with distributed database architecture in
different layer, each of which is connected through its root. The peers are
divided into three categories according to their physical stability and
strength. They are Ultra Super-peer, Super-peer and Ordinary Peer and we assign
these peers to first, second and third level of hierarchy respectively. Peers
in a group in lower layer have their own local database which hold as
associated super-peer in middle layer and access the database among the peers
through user queries. In our 3-layer hierarchical model for DHT algorithms, we
used an advanced Chord algorithm with optimized finger table which can remove
the redundant entry in the finger table in upper layer that influences the
system to reduce the lookup latency. Our research work finally resulted that
our model really provides faster search since the network lookup latency is
decreased by reducing the number of hops. The peers in such network then can
contribute with improve functionality and can perform well in P2P networks.


title: Convolution products for hypercomplex Fourier transforms

abstract:
  Hypercomplex Fourier transforms are increasingly used in signal processing
for the analysis of higher-dimensional signals such as color images. A main
stumbling block for further applications, in particular concerning filter
design in the Fourier domain, is the lack of a proper convolution theorem. The
present paper develops and studies two conceptually new ways to define
convolution products for such transforms. As a by-product, convolution theorems
are obtained that will enable the development and fast implementation of new
filters for quaternionic signals and systems, as well as for their higher
dimensional counterparts.


title:
Studies of homogeneous precipitation in very dilute iron-coper alloys
  using kinetic Monte Carlo simulations and statistical theory of nucleation

abstract:
  Kinetics of homogeneous nucleation and growth of copper precipitates under
electron irradiation of Fe_{1-x}Cu_x alloys at concentrations x from 0.06 at.%
to 0.4 at.% and temperatures T from 290 to 450C is studied using the kinetic
Monte Carlo (KMC) simulations and the statistical theory of nucleation (STN).
The conventional assumption about the similarity of mechanisms of precipitation
under electron irradiation and during thermal aging is adopted. The
earlier-developed ab initio model of interactions in Fe-Cu alloys is used for
both the KMC simulations and the STN calculations. Values of the nucleation
barrier F_c and the prefactor J_0 in the Zeldovich-Volmer relation for the
nucleation rate J are calculated for a number of concentrations and
temperatures. For the dilute alloys with x less then 0.2%, the STN and the KMC
results for the nucleation barrier F_c do virtually coincide with each other,
which seems to confirm a high reliability of the STN for this problem. The STN
calculations are also used to estimate the temperature dependencies of
concentrations which correspond to the homogeneous or the heterogeneous
precipitation limit and both dependencies are found to be rather sharp.


title: On the minimum FLOPs problem in the sparse Cholesky factorization

abstract:
  Prior to computing the Cholesky factorization of a sparse, symmetric positive
definite matrix, a reordering of the rows and columns is computed so as to
reduce both the number of fill elements in Cholesky factor and the number of
arithmetic operations (FLOPs) in the numerical factorization. These two metrics
are clearly somehow related and yet it is suspected that these two problems are
different. However, no rigorous theoretical treatment of the relation of these
two problems seems to have been given yet. In this paper we show by means of an
explicit, scalable construction that the two problems are different in a very
strict sense. In our construction no ordering, that is optimal for the fill, is
optimal with respect to the number of FLOPs, and vice versa.
  Further, it is commonly believed that minimizing the number of FLOPs is no
easier than minimizing the fill (in the complexity sense), but so far no proof
appears to be known. We give a reduction chain that shows the NP hardness of
minimizing the number of arithmetic operations in the Cholesky factorization.


title:
Inhomogeneous transport in model hydrated polymer electrolyte supported
  ultra-thin films

abstract:
  Structure of polymer electrolytes membranes, e.g., Nafion, inside fuel cell
catalyst layers has significant impact on the electrochemical activity and
transport phenomena that determine cell performance. In those regions, Nafion
can be found as an ultra-thin film, coating the catalyst and the catalyst
support surfaces. The impact of the hydrophilic/hydrophobic character of these
surfaces on the structural formation of the films and, in turn, on transport
properties, has not been sufficiently explored yet. Here, we report about
classical Molecular Dynamics simulations of hydrated Nafion thin-films in
contact with unstructured supports, characterized by their global wetting
properties only. We have investigated structure and transport in different
regions of the film and found evidences of strongly heterogeneous behavior. We
speculate about the implications of our work on experimental and technological
activity.


title: Extremal Limits of Rotating Black Holes

abstract:
  We consider non-extremal, stationary, axion-dilaton solutions to ungauged
symmetric supergravity models, obtained by Harrison transformations of the
non-extremal Kerr solution. We define a general algebraic procedure, which can
be viewed as an Inonu-Wigner contraction of the Noether charge matrix
associated with the effective D=3 sigma-model description of the solution,
yielding, through different singular limits, the known BPS and non-BPS extremal
black holes (which include the under-rotating non-BPS one). The non-extremal
black hole can thus be thought of as "interpolating" among these
limit-solutions. The algebraic procedure that we define generalizes the known
Rasheed-Larsen limit which yielded, in the Kaluza-Klein theory, the first
instance of under-rotating extremal solution. As an example of our general
result, we discuss in detail the non-extremal solution in the T^3-model, with
either (q_0, p^1) or (p^0, q_1) charges switched on, and its singular limits.
Such solutions, computed in D=3 through the solution-generating technique, is
completely described in terms of D=4 fields, which include the fully integrated
vector fields.


title: A simple proof of Andrews's 5F4 evaluation

abstract:
  We give a simple proof of George Andrews's balanced 5F4 evaluation using two
fundamental principles: the nth difference of a polynomial of degree less than
n is zero, and a polynomial of degree n that vanishes at n+1 points is
identically zero.


title: Neutrino Masses and Leptogenesis in Type I+II Seesaw Models

abstract:
  The baryon to photon ratio in the present Universe is very accurately
measured to be $(6.065 \pm 0.090) \times 10^{-10}$. We study the possible
origin of this baryon asymmetry in the neutrino sector through the generic
mechanism of baryogenesis through leptogenesis. We consider both type I and
type II seesaw origin of neutrino masses within the framework of left right
symmetric models (LRSM). Using the latest best fit global neutrino oscillation
data of mass squared differences, mixing angles and Dirac CP phase, we compute
the predictions for baryon to photon ratio keeping the Majorana CP phases as
free parameters for two different choices of lightest neutrino mass eigenvalue
for both normal and inverted hierarchical patterns of neutrino masses. We do
our calculation with and without lepton flavor effects being taken into
account. We choose different diagonal Dirac neutrino mass matrix for different
flavor effects in such a way that the lightest right handed neutrino mass is in
the appropriate range. We also study the predictions for baryon asymmetry when
the neutrino masses arise from a combination of both type I and type II seesaw
(with dominating type I term) and discriminate between several combinations of
Dirac and Majorana CP phases by demanding successful predictions for baryon
asymmetry.


title: Recognizing products of surfaces and simply connected 4-manifolds

abstract:
  We give necessary and sufficient conditions for a closed smooth 6-manifold N
to be diffeomorphic to a product of a surface F and a simply connected
4-manifold M in terms of basic invariants like the fundamental group and
cohomological data. Any isometry of the intersection form of M is realized by a
self-diffeomorphism of M x F.


title:
Family of Finite Geometry Low-Density Parity-Check Codes for Quantum Key
  Expansion

abstract:
  We consider a quantum key expansion (QKE) protocol based on
entanglement-assisted quantum error-correcting codes (EAQECCs). In these
protocols, a seed of a previously shared secret key is used in the
post-processing stage of a standard quantum key distribution protocol like the
Bennett-Brassard 1984 protocol, in order to produce a larger secret key. This
protocol was proposed by Luo and Devetak, but codes leading to good performance
have not been investigated. We look into a family of EAQECCs generated by
classical finite geometry (FG) low-density parity-check (LDPC) codes, for which
very efficient iterative decoders exist. A critical observation is that almost
all errors in the resulting secret key result from uncorrectable block errors
that can be detected by an additional syndrome check and an additional sampling
step. Bad blocks can then be discarded. We make some changes to the original
protocol to avoid the consumption of the preshared key when the protocol fails.
This allows us to greatly reduce the bit error rate of the key at the cost of a
minor reduction in the key production rate, but without increasing the
consumption rate of the preshared key. We present numerical simulations for the
family of FG LDPC codes, and show that this improved QKE protocol has a good
net key production rate even at relatively high error rates, for appropriate
choices of these codes.


title:
Improving Automatic Emotion Recognition from speech using Rhythm and
  Temporal feature

abstract:
  This paper is devoted to improve automatic emotion recognition from speech by
incorporating rhythm and temporal features. Research on automatic emotion
recognition so far has mostly been based on applying features like MFCCs, pitch
and energy or intensity. The idea focuses on borrowing rhythm features from
linguistic and phonetic analysis and applying them to the speech signal on the
basis of acoustic knowledge only. In addition to this we exploit a set of
temporal and loudness features. A segmentation unit is employed in starting to
separate the voiced/unvoiced and silence parts and features are explored on
different segments. Thereafter different classifiers are used for
classification. After selecting the top features using an IGR filter we are
able to achieve a recognition rate of 80.60 % on the Berlin Emotion Database
for the speaker dependent framework.


title: Stochastic Force Due to a Quantum Scalar Field in Minkowski Spacetime

abstract:
  A method is presented for computing approximate expressions for the
stochastic force term $\xi_{ab}$ which appears in the Einstein-Langevin
equation of stochastic gravity. Within this framework, $\xi_{ab}$ is a
stochastic tensor field whose probability distribution mimics the probability
distribution of the fluctuations of the quantum stress tensor operator; it is
defined to be a random tensor field of zero mean whose correlation function is
given by the expectation value of the symmetrized two point function of the
stress energy fluctuation operator, called the noise kernel. Approximate
expressions are obtained by means of a truncated Karhunen-Loeve transform
defined on a random lattice of spacetime points. Due to the singular nature of
the noise kernel, a coarse graining procedure is used to regulate divergences;
as a result, the expressions obtained for $\xi_{ab}$ approximate values which
might be seen by a probe measuring fluctuations in the stress energy using a
sampling profile of finite width. Two realizations of $\xi_{ab}$ in Minkowski
spacetime for the conformally invariant quantum scalar field in the Minkowski
vacuum state are presented.


title: Decision problems for word-hyperbolic semigroups

abstract:
  This paper studies decision problems for semigroups that are word-hyperbolic
in the sense of Duncan & Gilman. A fundamental investigation reveals that the
natural definition of a `word-hyperbolic structure' has to be strengthened
slightly in order to define a unique semigroup up to isomorphism. The
isomorphism problem is proven to be undecidable for word-hyperbolic semigroups
(in contrast to the situation for word-hyperbolic groups). It is proved that it
is undecidable whether a word-hyperbolic semigroup is automatic, asynchronously
automatic, biautomatic, or asynchronously biautomatic. (These properties do not
hold in general for word-hyperbolic semigroups.) It is proved that the uniform
word problem for word-hyperbolic semigroup is solvable in polynomial time
(improving on the previous exponential-time algorithm). Algorithms are
presented for deciding whether a word-hyperbolic semigroup is a monoid, a
group, a completely simple semigroup, a Clifford semigroup, or a free
semigroup.


title: On a Hardy-Littlewood theorem

abstract:
  A known Hardy-Littlewood theorem asserts that if both the function and its
conjugate are of bounded variation, then their Fourier series are absolutely
convergent. It is proved in the paper that the same result holds true for
functions on the whole axis and their Fourier transforms with certain
adjustments. The proof of the original Hardy-Littlewood theorem is derived from
the obtained assertion. It turned out that the former is a partial case of the
latter when the function is supposed to be of compact support. A similar result
as the obtained one but for radial functions is derived from the
one-dimensional case.


title: On K3 fibrations: towards mirror symmetry

abstract:
  Given X a K3 surface, a mirror dual to X can be identified with a component
of the moduli space of semistable sheaves on X. We consider fibrations by K3
surfaces over a one dimensional base that are Calabi-Yau and we charaterize the
dual fibration that turns to be derived equivalent to the original one relating
the problem to mirror symmetry.


title: Helical edge resistance introduced by charge puddles

abstract:
  We study the influence of electron puddles created by doping of a 2D
topological insulator on its helical edge conductance. A single puddle is
modeled by a quantum dot tunnel-coupled to the helical edge. It may lead to
significant inelastic backscattering within the edge because of the long
electron dwelling time in the dot. We find the resulting correction to the
perfect edge conductance. Generalizing to multiple puddles, we assess the
dependence of the helical edge resistance on temperature and doping level, and
compare it with recent experimental data.


title: Wang-Landau sampling: a criterion for halting the simulations

abstract:
  In this work we propose a criterion to finish the simulations of the
Wang-Landau sampling. Instead of determining a final modification factor for
all simulations and every sample sizes, we investigate the behavior of the
temperature of the peak of the specific heat during the simulations and finish
them when this value varies bellow a given limit. As a result, different runs
stop at different final modification factors. We show that in place of the
temperature of the peak of the specific heat one can adopt alternatively the
integrated heat transfer as a reference quantity. We apply this technique to
the two-dimensional Ising model and a homopolymer. We verify that for the Ising
model the mean order of the final modification factors are roughly the same for
all lattice sizes, but for the homopolymer the order of the final modification
factors increases with increasing polymer sizes. The results show that the
simulations can be halted much earlier then it is conventional in Wang-Landau
sampling, but manifold finite-size simulations are required in order to obtain
accurate results. A brief application to the three-dimensional Ising model is
also available.


title: Using the Big Ideas in Cosmology to Teach College Students

abstract:
  Recent advances in our understanding of the Universe have revolutionized our
view of its structure, composition and evolution. However, these new ideas have
not necessarily been used to improve the teaching of introductory astronomy
students. In this project, we have conducted research into student
understanding of cosmological ideas so as to develop effective web-based tools
to teach basic concepts important to modern cosmology. The tools are intended
for use at the introductory college level. Our research uses several
instruments, including open-ended and multiple choice surveys conducted at
multiple institutions, as well as interviews and course artifacts at one
institution, to ascertain what students know regarding modern cosmological
ideas, what common misunderstandings and misconceptions they entertain, and
what sorts of materials can most effectively overcome student difficulties in
learning this material. These data are being used to create a suite of
interactive, web-based tutorials that address the major ideas in cosmology
using real data. Having students engage with real data is a powerful means to
help students overcome certain misconceptions. Students master the scientific
concepts and reasoning processes that lead to our current understanding of the
universe through interactive tasks, prediction and reflection, experimentation,
and model building.


title: Global existence for the confined Muskat problem

abstract:
  In this paper we show global existence of Lipschitz continuous solution for
the stable Muskat problem with finite depth (confined) and initial data
satisfying some smallness conditions relating the amplitude, the slope and the
depth. The cornerstone of the argument is that, for these \emph{small} initial
data, both the amplitude and the slope remain uniformly bounded for all
positive times. We notice that, for some of these solutions, the slope can grow
but it remains bounded. This is very different from the infinite deep case,
where the slope of the solutions satisfy a maximum principle. Our work
generalizes a previous result where the depth is infinite.


title: Operator integrals and sesquilinear forms

abstract:
  We consider various systematic ways of defining unbounded operator valued
integrals of complex functions with respect to (mostly) positive operator
measures and positive sesquilinear form measures, and investigate their
relationships to each other in view of the extension theory of symmetric
operators. We demonstrate the associated mathematical subtleties with a
physically relevant example involving moment operators of the momentum
observable of a particle confined to move on a bounded interval.


title: Non-universal disordered Glauber dynamics

abstract:
  We consider the one-dimensional Glauber dynamics with coupling disorder in
terms of bilinear fermion Hamiltonians. Dynamic exponents embodied in the
spectrum gap of these latter are evaluated numerically by averaging over both
binary and Gaussian disorder realizations. In the first case, these exponents
are found to follow the non-universal values of those of plain dimerized
chains. In the second situation their values are still non-universal and
sub-diffusive below a critical variance above which, however, the relaxation
time is suggested to grow as a stretched exponential of the equilibrium
correlation length.


title:
Far from equilibrium maximal principle leading to matter
  self-organization

abstract:
  In this work an extremal principle driving the far from equilibrium evolution
of a system of structureless particles is derived by using the stochastic
quantum hydrodynamic analogy. For a classical phase (i.e., the quantum
correlations decay on a distance smaller than the mean inter-molecular
distance) the far from equilibrium kinetic equation can be cast in the form of
a Fokker-Plank equation whose phase space velocity vector maximizes the
dissipation of the energy-type function, named here, stochastic free energy.
Near equilibrium the maximum stochastic free energy dissipation is shown to be
compatible with the Prigogine s principle of minimum entropy production.
Moreover, in the case of elastic molecular collisions and in absence of
chemical reactions, in quasi-isothermal far from equilibrium states, the theory
shows that the maximum stochastic free energy dissipation reduces to the
maximum free energy dissipation. Following the tendency to reach the highest
rate of stochastic free energy dissipation, the system transition to states
with higher free energy can happen. Given that in incompressible ordinary
fluids such an increase of free energy is almost given by a decrease of
entropy, the matter self-organization becomes possible. When chemical reactions
or relevant thermal gradients are present, the theory highlights that the
Sawada enunciation of maximum free energy dissipation can be violated. The
proposed model depicts the Prigogine s principle of minimum entropy production
near-equilibrium and the far from equilibrium Sawada s principle of maximum
energy dissipation as two complementary principia of a unique theory where the
latter one is a particular case of the more general one of maximum stochastic
free energy dissipation.


title:
Constraints on Disformal Couplings from the Properties of the Cosmic
  Microwave Background Radiation

abstract:
  Certain modified gravity theories predict the existence of an additional,
non-conformally coupled scalar field. A disformal coupling of the field to the
Cosmic Microwave Background (CMB) is shown to affect the evolution of the
energy density in the radiation fluid and produces a modification of the
distribution function of the CMB, which vanishes if photons and baryons couple
in the same way to the scalar. We find the constraints on the couplings to
matter and photons coming from the measurement of the CMB temperature evolution
and from current upper limits on the $\mu$--distortion of the CMB spectrum. We
also point out that the measured equation of state of photons differs from
$w_\gamma = 1/3$ in the presence of disformal couplings.


title: Angle-Resolved Photoemission from Cuprates with Static Stripes

abstract:
  25 years after discovery of high-temperature superconductivity (HTSC) in
La$_{2-x}$Ba$_x$CuO$_4$ (LBCO), the HTSC continues to pose some of the biggest
challenges in materials science. Cuprates are fundamentally different from
conventional superconductors in that the metallic conductivity and
superconductivity are induced by doping carriers into an antiferromagnetically
ordered correlated insulator. In such systems, the normal state is expected to
be quite different from a Landau-Fermi liquid - the basis for the conventional
BCS theory of superconductivity. The situation is additionally complicated by
the fact that cuprates are susceptible to charge/spin ordering tendencies,
especially in the low-doping regime. The role of such tendencies on the
phenomenon of superconductivity is still not completely clear. Here, we present
studies of the electronic structure in cuprates where the superconductivity is
strongly suppressed as static spin and charge orders or stripes develop near
the doping level of $x =1/8$ and outside of the superconducting dome, for
$x<0.055$. We discuss the relationship between the stripes, superconductivity,
pseudogap and the observed electronic excitations in these materials.


title: Theory of atomistic simulation of spin-transfer torque in nanomagnets

abstract:
  In spin-transfer torque (STT) for technological applications, the
miniaturization of the magnet may reach the stage of requiring a fully
quantum-mechanical treatment. We present an STT theory which uses the quantum
macrospin ground and excited (magnon) states of the nanomagnet. This allows for
energy and angular momentum exchanges between the current electron and the
nano-magnet. We develop a method of magnetization dynamics simulation which
captures the heating effect on the magnet by the spin-polarized current and the
temperature-dependence in STT. We also discuss the magnetostatics effect on
magnon scattering for ferromagnetic relaxation in a thin film. Our work
demonstrates a realistic step towards simulation of quantum spin-transfer
torque physics in nano-scale magnets.


title:
Probing interactions within the dark matter sector via extra radiation
  contributions

abstract:
  The nature of dark matter is one of the most thrilling riddles for both
cosmology and particle physics nowadays. While in the typical models the dark
sector is composed only by weakly interacting massive particles, an arguably
more natural scenario would include a whole set of gauge interactions which are
invisible for the standard model but that are in contact with the dark matter.
We present a method to constrain the number of massless gauge bosons and other
relativistic particles that might be present in the dark sector using current
and future cosmic microwave background data, and provide upper bounds on the
size of the dark sector. We use the fact that the dark matter abundance depends
on the strength of the interactions with both sectors, which allows one to
relate the freeze-out temperature of the dark matter with the temperature of
{this cosmic background of dark gauge bosons}. This relation can then be used
to calculate how sizable is the impact of the relativistic dark sector in the
number of degrees of freedom of the early Universe, providing an interesting
and testable connection between cosmological data and direct/indirect detection
experiments. The recent Planck data, in combination with other cosmic microwave
background experiments and baryonic acoustic oscillations data, constrains the
number of relativistic dark gauge bosons, when the freeze-out temperature of
the dark matter is larger than the top mass, to be N \lesssim 14 for the
simplest scenarios, while those limits are slightly relaxed for the combination
with the Hubble constant measurements to N \lesssim 20. Future releases of
Planck data are expected to reduce the uncertainty by approximately a factor 3,
what will reduce significantly the parameter space of allowed models.


title: Epsilon-complexity of continuous functions

abstract:
  A formal definition of epsilon-complexity of an individual continuous
function defined on a unit cube is proposed. This definition is consistent with
the Kolmogorov's idea of the complexity of an object. A definition of
epsilon-complexity for a class of continuous functions with a given modulus of
continuity is also proposed. Additionally, an explicit formula for the
epsilon-complexity of a functional class is obtained. As a consequence, the
paper finds that the epsilon-complexity for the Holder class of functions can
be characterized by a pair of real numbers. Based on these results the papers
formulates a conjecture concerning the epsilon-complexity of an individual
function from the Holder class. We also propose a conjecture about
characterization of epsilon-complexity of a function from the Holder class
given on a discrete grid.

categories: math-ph cs.IT math.IT math.MP physics.data-an


title:
Analytical Model of Proportional Fair Scheduling in Interference-limited
  OFDMA/LTE Networks

abstract:
  Various system tasks like interference coordination, handover decisions,
admission control etc. in upcoming cellular networks require precise mid-term
(spanning over a few seconds) performance models. Due to channel-dependent
scheduling at the base station, these performance models are not simple to
obtain. Furthermore, upcoming cellular systems will be interference-limited,
hence, the way interference is modeled is crucial for the accuracy. In this
paper we present an analytical model for the SINR distribution of the
\textit{scheduled} subcarriers of an OFDMA system with proportional fair
scheduling. The model takes the precise SINR distribution into account. We
furthermore refine our model with respect to uniform modulation and coding, as
applied in LTE networks. The derived models are validated by means of
simulations. In additon, we show that our models are approximate estimators for
the performance of rate-based proportional fair scheduling, while they
outperform some simpler prediction models from related work significantly.


title:
Shape and Chirality Transitions in Off-Axis Twist Nematic Elastomer
  Ribbons

abstract:
  Using both experiments and finite element simulations, we explore the shape
evolution of off-axis nematic elastomer ribbons as a function of temperature.
The elastomers are prepared by cross-linking the mesogens with planar anchoring
of the director at top and bottom surfaces with a 90 degree left-handed twist.
Shape evolution depends sensitively on the off-axis director orientation at the
sample mid-plane. When the director at midplane is parallel to either the
ribbon's long or short axes, ribbons form either helicoids or spirals depending
on the aspect ratio and temperature. If the director at midplane is more than 5
degrees off-axis, then they form only spiral ribbons. Samples in all these
geometries show a remarkable transition from right- to left-handed chiral
shapes on change of temperature. Simulation studies provide insight into the
mechanisms driving shape evolution and enable engineering design of these
materials for future applications.


title:
A Grid of 3D Stellar Atmosphere Models of Solar Metallicity: I. General
  Properties, Granulation and Atmospheric Expansion

abstract:
  Present grids of stellar atmosphere models are the workhorses in interpreting
stellar observations, and determining their fundamental parameters. These
models rely on greatly simplified models of convection, however, lending less
predictive power to such models of late type stars.
  We present a grid of improved and more reliable stellar atmosphere models of
late type stars, based on deep, 3D, convective, stellar atmosphere simulations.
This grid is to be used in general for interpreting observations, and improve
stellar and asteroseismic modeling.
  We solve the Navier Stokes equations in 3D and concurrent with the radiative
transfer equation, for a range of atmospheric parameters, covering most of
stellar evolution with convection at the surface. We emphasize use of the best
available atomic physics for quantitative predictions and comparisons with
observations.
  We present granulation size, convective expansion of the acoustic cavity,
asymptotic adiabat, as function of atmospheric parameters. These and other
results are also available in electronic form.


title:
Universal fluctuations and extreme statistics of avalanches near the
  depinning transtition

abstract:
  We derive exact predictions for universal scaling exponents and scaling
functions associated with the statistics of maximum velocities vm during
avalanches described by the mean field theory of the interface depinning
transition. In particular, we find a robust power-law regime in the statistics
of maximum events that can explain the observed distribution of the peak
amplitudes in acoustic emission experiments of crystal plasticity. Our results
are expected to be broadly applicable to a broad range of systems in the
mean-field interface depinning universality class, ranging from magnets to
earthquakes.


title: Non-Associative Geometry and the Spectral Action Principle

abstract:
  Chamseddine and Connes have argued that the action for Einstein gravity,
coupled to the SU(3)\times SU(2)\times U(1) standard model of particle physics,
may be elegantly recast as the "spectral action" on a certain "non-commutative
geometry." In this paper, we show how this formalism may be extended to
"non-associative geometries," and explain the motivations for doing so. As a
guiding illustration, we present the simplest non-associative geometry (based
on the octonions) and evaluate its spectral action: it describes Einstein
gravity coupled to a G_2 gauge theory, with 8 Dirac fermions (which transform
as a singlet and a septuplet under G_2). This is just the simplest example: in
a forthcoming paper we show how to construct more realistic models that include
Higgs fields, spontaneous symmetry breaking and fermion masses.


title:
Distribution of maximum velocities in avalanches near the depinning
  transition

abstract:
  We report exact predictions for universal scaling exponents and scaling
functions associated with the distribution of the maximum collective avalanche
propagation velocities $v_m$ in the mean field theory of the interface
depinning transition. We derive the extreme value distribution $P(v_m|T)$ for
the maximum velocities in avalanches of fixed duration $T$, and verify the
results by numerical simulation near the critical point. We find that the tail
of the distribution of maximum velocity for an arbitrary avalanche duration,
$v_m$, scales as $P(v_m)\sim v_m^{-2}$ for large $v_m$. These results account
for the observed power-law distribution of the maximum amplitudes in acoustic
emission experiments of crystal plasticity, and are also broadly applicable to
other systems in the mean-field interface depinning universality class, ranging
from magnets to earthquakes.