title: Existence of an endogenously complete equilibrium driven by a diffusion

abstract:
  The existence of complete Radner equilibria is established in an economy
which parameters are driven by a diffusion process. Our results complement
those in the literature. In particular, we work under essentially minimal
regularity conditions and treat time-inhomogeneous case.


title:
Crossover of magnetoresistance in the zerogap half-metallic Heusler
  alloy Fe2CoSi

abstract:
  This work reports on the band structure and magneto-transport investigations
of the inverse Heusler compound Fe2CoSi. The first-principles calculations
reveal that Fe2CoSi has a very peculiar band structure with a conducting
property in the majority spin channel and a nearly zero bandgap in the minority
spin channel. The synthesized Fe2CoSi sample shows a high-ordered inverse
Heusler structure with a magnetic moment of 4.88 {\mu}B at 5 K and a high Curie
temperature of 1038 K. With increasing temperature, a crossover from positive
to negative magnetoresistance (MR) is observed. Complemented with the Hall
effect measurements, we suggest the intriguing crossover of MR can be ascribed
to the dominant spin carriers changing from the gapless minority spin channel
to the majority spin channel at Fermi level.


title:
Trust in the CODA model: Opinion Dynamics and the reliability of other
  agents

abstract:
  A model for the joint evolution of opinions and how much the agents trust
each other is presented. The model is built using the framework of the
Continuous Opinions and Discrete Actions (CODA) model. Instead of a fixed
probability that the other agents will decide in the favor of the best choice,
each agent considers that other agents might be one one of two types:
trustworthy or useless. Trustworthy agents are considered more likely to be
right than wrong, while the opposite holds for useless ones. Together with the
opinion about the discussed issue, each agent also updates that probability for
each one of the other agents it interacts withe probability each one it
interacts with is of one type or the other. The dynamics of opinions and the
evolution of the trust between the agents are studied. Clear evidences of the
existence of two phases, one where strong polarization is observed and the
other where a clear division is permanent and reinforced are observed. The
transition seems signs of being a first-order transition, with a location
dependent on both the parameters of the model and the initial conditions. This
happens despite the fact that the trust network evolves much slower than the
opinion on the central issue.


title:
GreenDCN: a General Framework for Achieving Energy Efficiency in Data
  Center Networks

abstract:
  The popularization of cloud computing has raised concerns over the energy
consumption that takes place in data centers. In addition to the energy
consumed by servers, the energy consumed by large numbers of network devices
emerges as a significant problem. Existing work on energy-efficient data center
networking primarily focuses on traffic engineering, which is usually adapted
from traditional networks. We propose a new framework to embrace the new
opportunities brought by combining some special features of data centers with
traffic engineering. Based on this framework, we characterize the problem of
achieving energy efficiency with a time-aware model, and we prove its
NP-hardness with a solution that has two steps. First, we solve the problem of
assigning virtual machines (VM) to servers to reduce the amount of traffic and
to generate favorable conditions for traffic engineering. The solution reached
for this problem is based on three essential principles that we propose.
Second, we reduce the number of active switches and balance traffic flows,
depending on the relation between power consumption and routing, to achieve
energy conservation. Experimental results confirm that, by using this
framework, we can achieve up to 50 percent energy savings. We also provide a
comprehensive discussion on the scalability and practicability of the
framework.


title:
Discontinuous Electromagnetic Fields Using Huygens Sources For Wavefront
  Manipulation

abstract:
  We introduce the idea of discontinuous electric and magnetic fields at a
boundary to design and shape wavefronts in an arbitrary manner. To create this
discontinuity in the field we use electric and magnetic currents which act like
a Huygens source to radiate the desired wavefront. These currents can be
synthesized either by an array of electric and magnetic dipoles or by a
combined impedance and admittance surface. A dipole array is an active
implementation to impose discontinuous fields while the impedance/admittance
surface acts as a passive one. We then expand on our previous work showing how
electric and magnetic dipole arrays can be used to cloak an object
demonstrating two novel cloaking schemes. We also show how to arbitrarily
refract a beam using a set of impedance and admittance surfaces. Refraction
using the idea of discontinuous fields is shown to be a more general case of
refraction using phase discontinuities.


title: The Fiber Walk: A Model of Tip-Driven Growth with Lateral Expansion

abstract:
  Tip-driven growth processes underlie the development of many plants. To date,
tip-driven growth processes have been modelled as an elongating path or series
of segments without taking into account lateral expansion during elongation.
Instead, models of growth often introduce an explicit thickness by expanding
the area around the completed elongated path. Modelling expansion in this way
can lead to contradictions in the physical plausibility of the resulting
surface and to uncertainty about how the object reached certain regions of
space. Here, we introduce "fiber walks" as a self-avoiding random walk model
for tip-driven growth processes that includes lateral expansion. In 2D, the
fiber walk takes place on a square lattice and the space occupied by the fiber
is modelled as a lateral contraction of the lattice. This contraction
influences the possible follow-up steps of the fiber walk. The boundary of the
area consumed by the contraction is derived as the dual of the lattice faces
adjacent to the fiber. We show that fiber walks generate fibers that have
well-defined curvatures, enable the identification of the process underlying
the occupancy of physical space. Hence, fiber walks provide a base from which
to model both the extension and expansion of physical biological objects with
finite thickness.


title: Boundary Value Problems on a Half Sierpinski Gasket

abstract:
  We study boundary value problems for the Laplacian on a domain $\Omega$
consisting of the left half of the Sierpinski Gasket ($SG$), whose boundary is
essentially a countable set of points $X$. For harmonic functions we give an
explicit Poisson integral formula to recover the function from its boundary
values, and characterize those that correspond to functions of finite energy.
We give an explicit Dirichlet to Neumann map and show that it is invertible. We
give an explicit description of the Dirichlet to Neumann spectra of the
Laplacian with an exact count of the dimensions of eigenspaces. We compute the
exact trace spaces on $X$ of the $L^2$ and $L^\infty$ domains of the Laplacian
on $SG$. In terms of the these trace spaces, we characterize the functions in
the $L^2$ and $L^\infty$ domains of the Laplacian on $\Omega$ that extend to
the corresponding domains on $SG$, and give an explicit linear extension
operator in terms of piecewise biharmonic functions.


title: Dixmier approximation and symmetric amenability for C*-algebras

abstract:
  We study some general properties of tracial C*-algebras. In the first part,
we consider Dixmier type approximation theorem and characterize symmetric
amenability for C*-algebras. In the second part, we consider continuous bundles
of tracial von Neumann algebras and classify some of them.


title:
Characterization of tricyclic graphs with exactly two $Q$-main
  eigenvalues

abstract:
  The signless Laplacian matrix of a graph $G$ is defined to be the sum of its
adjacency matrix and degree diagonal matrix, and its eigenvalues are called
$Q$-eigenvalues of $G$. A $Q$-eigenvalue of a graph $G$ is called a $Q$-main
eigenvalue if it has an eigenvector the sum of whose entries is not equal to
zero. Chen and Huang [L. Chen, Q.X. Huang, Trees, unicyclic graphs and bicyclic
graphs with exactly two $Q$-main eigenvalues, submitted for publication]
characterized all trees, unicylic graphs and bicyclic graphs with exactly two
main $Q$-eigenvalues, respectively. As a continuance of it, in this paper, all
tricyclic graphs with exactly two $Q$-main eigenvalues are characterized.


title: The relaxation of a family of broken bond crystal surface models

abstract:
  We study the continuum limit of a family of kinetic Monte Carlo models of
crystal surface relaxation that includes both the solid-on-solid and discrete
Gaussian models. With computational experiments and theoretical arguments we
are able to derive several partial differential equation limits identified (or
nearly identified) in previous studies and to clarify the correct choice of
surface tension appearing in the PDE and the correct scaling regime giving rise
to each PDE. We also provide preliminary computational investigations of a
number of interesting qualitative features of the large scale behavior of the
models.


title:
Method of Relative Magnetic Helicity Computation II: Boundary Conditions
  for the Vector Potentials

abstract:
  We have proposed a method to calculate the relative magnetic helicity in a
finite volume as given the magnetic field in the former paper (Yang et al. {\it
Solar Physics}, {\bf 283}, 369, 2013). This method requires that the magnetic
flux to be balanced on all the side boundaries of the considered volume. In
this paper, we propose a scheme to obtain the vector potentials at the
boundaries to remove the above restriction. We also used a theoretical model
(Low and Lou, {\it Astrophys. J.} {\bf 352}, 343, 1990) to test our scheme.


title:
Long-lifetime Polariton BEC in a Microcavity with an Embedded Quantum
  Well and Graphene

abstract:
  We study the propagation of a Bose-Einstein condensate (BEC) of long-lifetime
exciton polaritons in a high-quality microcavity with an embedded semiconductor
quantum well or a graphene layer using the Gross-Pitaevskii equation. It is
shown that in these heterostructures the BEC of the long-lifetime polaritons
can propagate over the distance up to 0.5 mm. The obtained results are
consistent with the recent experimental observations for GaAs/AlGaAs
microcavity. It is demonstrated that the BEC density in a polariton trace in a
microcavity with embedded graphene at large distances from the excitation spot
is higher for the microcavity with higher dielectric constant. It is also
predicted that the propagation of a polariton BEC in a microcavity with
graphene is dynamically tunable by changing the gap energy, that makes it
potentially useful for applications in integrated optical circuits.


title: Three Trichotomy Theorems

abstract:
  We study the following kth order rational difference equation assuming
nonnegative parameters and nonnegative initial conditions
$$x_{n}=\frac{\alpha+\sum_{i=1}^{k}\beta_{i}x_{n-i}}
{A+\sum_{j=1}^{k}B_{j}x_{n-j}},\quad n\in\mathbb{N}.$$ We develop a new
periodic trichotomy result which unifies all currently known periodic
trichotomy results regarding the above difference equation into three major
families. The periodic trichotomy result presented in this article also
contains as special cases some new examples of periodic trichotomy behavior.


title: Galaxy Morphology

abstract:
  Galaxy morphology has many structures that are suggestive of various
processes or stages of secular evolution. Internal perturbations such as bars
can drive secular evolution through gravity torques that move gas into the
central regions and build up a flattened, disk-like central bulge, or which may
convert an open spiral pseudoring into a more closed ring. Interaction between
individual components of a galaxy, such as between a bar and a dark halo, a bar
and a central mass concentration, or between a perturbation and the basic state
of a stellar disk, can also drive secular transformations. In this series of
lectures, I review many aspects of galaxy morphology with a view to delineating
some of the possible evolutionary pathways between different galaxy types.


title:
On the number of solutions of the generalized Ramanujan-Nagell equation
  $D_{1}x^2+D_{2}^{m}=2^{n+2}$}

abstract:
  Let $D_{1}$, $D_{2}$ be coprime odd integers with min$(D_{1},D_{2})>1$, and
let $N(D_{1},D_{2})$ denote the number of positive integer solutions $(x, m,
n)$ of the equation $D_{1}x^2+D_{2}^{m}=2^{n+2}$. In this paper, we prove that
$N(D_{1},D_{2})\leq 2$ except for $N(3,5)=N(5,3)=4$ and $N(13,3)=N(31,97)=3$.


title:
Compressed Sensing and Affine Rank Minimization under Restricted
  Isometry

abstract:
  This paper establishes new restricted isometry conditions for compressed
sensing and affine rank minimization. It is shown for compressed sensing that
$\delta_{k}^A+\theta_{k,k}^A < 1$ guarantees the exact recovery of all $k$
sparse signals in the noiseless case through the constrained $\ell_1$
minimization. Furthermore, the upper bound 1 is sharp in the sense that for any
$\epsilon > 0$, the condition $\delta_k^A + \theta_{k, k}^A < 1+\epsilon$ is
not sufficient to guarantee such exact recovery using any recovery method.
Similarly, for affine rank minimization, if
$\delta_{r}^\mathcal{M}+\theta_{r,r}^\mathcal{M}< 1$ then all matrices with
rank at most $r$ can be reconstructed exactly in the noiseless case via the
constrained nuclear norm minimization; and for any $\epsilon > 0$,
$\delta_r^\mathcal{M} +\theta_{r,r}^\mathcal{M} < 1+\epsilon$ does not ensure
such exact recovery using any method. Moreover, in the noisy case the
conditions $\delta_{k}^A+\theta_{k,k}^A < 1$ and
$\delta_{r}^\mathcal{M}+\theta_{r,r}^\mathcal{M}< 1$ are also sufficient for
the stable recovery of sparse signals and low-rank matrices respectively.
Applications and extensions are also discussed.


title: Efficient Spin Squeezing with Optimized Pulse Sequences

abstract:
  Spin squeezed states are a class of entangled states of spins that have
practical applications to precision measurements. In recent years spin
squeezing with one-axis twisting (OAT) has been demonstrated experimentally
with spinor BECs with more than 10^3 atoms. Although the noise is below the
standard quantum limit, the OAT scheme cannot reduce the noise down to the
ultimate Heisenberg limit. Here we propose an experimentally feasible scheme
based on optimized quantum control to greatly enhance the performance of OAT to
approach the Heisenberg limit, requiring only an OAT Hamiltonian and the use of
several coherent driving pulses. The scheme is robust against technical noise
and can be readily implemented for spinor BECs or trapped ions with current
technology.


title: Interaction effect in two-dimensional Dirac fermions

abstract:
  Based on the Dirac equations in the two-dimensional $\pi-$ flux model, we
study the interaction effects both in nontrivial gapped and gapless Dirac
equations with numerical exact diagonalization method. In the presence of the
nearest and next nearest neighbor interactions: for nontrivial gapped Dirac
equation, the topological phase is robust and persists in a finite region of
the phase diagram; while for gapless Dirac equation, charge-density-wave and
stripe phases are identified and the phase diagram in $(V_1, V_2)$ plane is
obtained. When the next-next-nearest neighbor interaction is further included
to gapless Dirac equation, the topological phase expected in the mean-field
theory is absent. Our results are related to the possibility of dynamically
generating topological phase from the electronic correlations.


title:
Noncollinear magnetism and half-metallicity in biased bilayer zigzag
  graphene nanoribbons

abstract:
  We study in this paper the edge polarizations and their consequences for a
biased Bernal stacked bilayer graphene nanoribbon with zigzag termination. The
magnetic states are classified according to the interlayer and intralayer
couplings between the edge polarizations, and the magnetic phase diagram of
doping versus bias voltage is given. Coplanar magnetic phase is found and the
variation of its magnetic structure with the bias voltage is investigated. For
all the magnetic states, we also discuss the possibility of the
half-metallicity, and for a ribbon with perfect zigzag edges we predict seven
kinds of the half-metallic states, which are characterized by their distinct
magnetic structures and quantized electrical conductances along the ribbon.


title:
Current Studies On Intrusion Detection System, Genetic Algorithm And
  Fuzzy Logic

abstract:
  Nowadays Intrusion Detection System (IDS) which is increasingly a key element
of system security is used to identify the malicious activities in a computer
system or network. There are different approaches being employed in intrusion
detection systems, but unluckily each of the technique so far is not entirely
ideal. The prediction process may produce false alarms in many anomaly based
intrusion detection systems. With the concept of fuzzy logic, the false alarm
rate in establishing intrusive activities can be reduced. A set of efficient
fuzzy rules can be used to define the normal and abnormal behaviors in a
computer network. Therefore some strategy is needed for best promising security
to monitor the anomalous behavior in computer network. In this paper I present
a few research papers regarding the foundations of intrusion detection systems,
the methodologies and good fuzzy classifiers using genetic algorithm which are
the focus of current development efforts and the solution of the problem of
Intrusion Detection System to offer a realworld view of intrusion detection.
Ultimately, a discussion of the upcoming technologies and various methodologies
which promise to improve the capability of computer systems to detect
intrusions is offered.


title:
Restriction estimates via the derivatives of the heat semigroup and
  connexion with dispersive estimates

abstract:
  We consider an abstract non-negative self-adjoint operator $H$ on an
$L^2$-space. We derive a characterization for the restriction estimate $\|
dE_H(\lambda) \|_{L^p \to L^{p'}} \le C \lambda^{\frac{d}{2}(\frac{1}{p} -
\frac{1}{p'}) -1}$ in terms of higher order derivatives of the semigroup
$e^{-tH}$. We provide an alternative proof of a result in [1] which asserts
that dispersive estimates imply restriction estimates. We also prove
$L^p-L^{p'}$ estimates for the derivatives of the spectral resolution of $H$.


title:
Tracers of chromospheric structure. I. CaII H$\&$K emission distribution
  of 13000 F, G and K stars in SDSS DR7 spectroscopic sample

abstract:
  We present chromospheric activity index $S\rm_{HK}$ measurements for over
13,000 F, G and K disk stars with high signal-to-noise ratio ($>$ 60) spectra
in the Sloan Digital Sky Survey (SDSS) Data Release 7 (DR7) spectroscopic
sample. A parameter $\delta$S is defined as the difference between $S\rm_{HK}$
and a `zero' emission line fitted by several of the most inactive stars. The
$S\rm_{HK}$ indices of subgiant stars tend to be much lower than dwarfs, which
provide a way to distinguish dwarfs and giants with relatively low resolution
spectra. Cooler stars are generally more active and display a larger scatter
than hotter stars. Stars associated with the thick disk are in general less
active than those of the thin disk. The fraction of K dwarfs that are active
drops with vertical distance from the Galactic plane. Metallicity affects
$S\rm_{HK}$ measurements differently among F, G and K dwarfs in this sample.
Using the open clusters NGC 2420, M67 and NGC6791 as calibrations, ages of most
field stars in this SDSS sample range from 3-8 Gyr.


title: The arithmetic Hodge index theorem for adelic line bundles I

abstract:
  This is the first paper of a series. We prove an arithmetic Hodge index
theorem for adelic line bundles on projective varieties over number fields. It
extends the arithmetic Hodge index theorem of Faltings, Hriljac and Moriwaki on
arithmetic varieties. As consequences, we obtain the uniqueness part of the
non-archimedean Calabi--Yau theorem, and a rigidity property of the sets of
preperiodic points of polarizable algebraic dynamical systems over number
fields.


title: The arithmetic Hodge index theorem for adelic line bundles II

abstract:
  This is the second paper of a series. It extends the results of the first
paper from number fields to finitely generated fields, based on the recent
theory of adelic line bundles of the same authors. We prove an arithmetic Hodge
index theorem for these adelic line bundles, and apply the theorem to obtain a
rigidity property of the sets of preperiodic points of polarizable algebraic
dynamical systems over any field.


title:
Interacting Electron Wave Packet Dynamics in a Two-dimensional
  Nanochannel

abstract:
  Classical and quantum dynamics are important limits for the understanding of
the transport characteristics of interacting electrons in nanodevices. Here we
apply an intermediate semiclassical approach to investigate the dynamics of two
interacting electrons in a planar nanochannel as a function of Coulomb
repulsion and electric field. We find that charge is mostly redistributed to
the channel edges and that an electric field enhances the particle-like
character of electrons. These results may have significant implications for the
design and study of future nanodevices.


title:
A modified dna computing approach to tackle the exponential solution
  space of the graph coloring problem

abstract:
  Although it has been evidenced that DNA computing is able to solve the graph
coloring problem in a polynomial time complexity, but the exponential solution
space is still a restrictive factor in applying this technique for solving
really large problems. In this paper a modified DNA computing approach based on
Adleman-Lipton model is proposed which tackles the mentioned restriction by
coloring the vertices one by one. In each step, it expands the DNA strands
encoding promising solutions and discards those which encode infeasible ones. A
sample graph is colored by simulating the proposed approach and shows a notable
reduction in the number of DNA strands used.


title: Seismic modeling using the frozen Gaussian approximation

abstract:
  We adopt the frozen Gaussian approximation (FGA) for modeling seismic waves.
The method belongs to the category of ray-based beam methods. It decomposes
seismic wavefield into a set of Gaussian functions and propagates these
Gaussian functions along appropriate ray paths. As opposed to the classic
Gaussian-beam method, FGA keeps the Gaussians frozen (at a fixed width) during
the propagation process and adjusts their amplitudes to produce an accurate
approximation after summation. We perform the initial decomposition of seismic
data using a fast version of the Fourier-Bros-Iagolnitzer (FBI) transform and
propagate the frozen Gaussian beams numerically using ray tracing. A test using
a smoothed Marmousi model confirms the validity of FGA for accurate modeling of
seismic wavefields.


title: Zeros of Witten zeta functions and absolute limit

abstract:
  We introduce multiple versions of L-functions for Witten zeta functions. We
study their algebraic and analytic properties. Especially we investigate the
existence of zeros at negative integers. These results strongly suggest the
universal zero at -2. We look at their absolute limits also.


title:
Iterated Gain-based Stochastic Filters for Dynamic System
  Identification: Annealing-type Iterations and the Filter Bank

abstract:
  A novel form of nonlinear stochastic filtering employing an annealing-type
iterative update scheme, aided by the introduction of an artificial diffusion
parameter and based on the Gaussian sum approximations of the prior and
posterior densities, is presented. The proposed Monte Carlo filter bank
conforms in structure to the parent nonlinear filtering (Kushner-Stratonovich)
equation, as reflected in the additive gain-based updates, and possesses
excellent mixing properties enabling better explorations of the phase space of
the state vector. The performance of the filter bank, presently assessed
against a few carefully chosen numerical examples, provide ample evidence of
its substantively improved performance in terms of filter convergence and
estimation accuracy vis-\`a-vis a few other competing filters especially in
higher dimensional dynamic system identification problems including cases that
may demand estimating relatively minor variations in the parameter values from
their reference states.


title:
Ferroelectric nanodomains in epitaxial PbTiO3 films grown on SmScO3 and
  TbScO3 substrates

abstract:
  Domain structures of 320 nm thin epitaxial films of ferroelectric PbTiO3
grown by MOCVD technique in identical conditions on SmScO3 and TbScO3
perovskite sub- strates have been investigated by Raman spectroscopy and
piezoresponse force microscopy techniques. Phonon frequency shifts and typical
domain structure motifs are discussed. The results reveal strikingly different
domain structure architecture: domain structures of the PbTiO3 film grown on
SmScO3 have dominantly a-domain orientation while strongly preferential
c-domain orientation was found in the PbTiO3 film grown on the TbScO3
substrate. Differences between the two cases are traced back to the
film-substrate lattice mismatch at the deposition temperature.


title: The Meat of the Matter: A thumb rule for scavenging dogs?

abstract:
  Animals that scavenge in and around human localities need to utilize a broad
range of resources. Preference for any one kind of food, under such
circumstances, might be inefficient. Indian free-ranging dogs, Canis lupus
familiaris are scavengers that are heavily dependent on humans for sustaining
their omnivorous diet. The current study suggests that because of evolutionary
load, these dogs, which are descendants of the decidedly carnivorous gray wolf,
still retain a preference for meat though they live on carbohydrate-rich
resources. The plasticity in their diet probably fosters efficient scavenging
in a competitive environment, while a thumb rule for preferentially acquiring
specific nutrients enables them to sequester proteins from the
carbohydrate-rich environment.


title:
Experimental observation of optical precursors in optically pumped
  crystals

abstract:
  We experimentally observed optical precursors in optically pumped crystals
using polarization-based interference. By switching the user-programmable
medium among the fast light, slow light and no-dispersion regimes, we observed
an unchanged polarization states for the wavefronts. The robust
polarization-encoded information carried by wavefronts suggests that precursors
are the preferred carriers for both quantum and classical information in
communication networks.


title: Crowdsourcing Dilemma

abstract:
  Crowdsourcing offers unprecedented potential for solving tasks efficiently by
tapping into the skills of large groups of people. A salient feature of
crowdsourcing---its openness of entry---makes it vulnerable to malicious
behavior. Such behavior took place in a number of recent popular crowdsourcing
competitions. We provide game-theoretic analysis of a fundamental tradeoff
between the potential for increased productivity and the possibility of being
set back by malicious behavior. Our results show that in crowdsourcing
competitions malicious behavior is the norm, not the anomaly---a result
contrary to the conventional wisdom in the area. Counterintuitively, making the
attacks more costly does not deter them but leads to a less desirable outcome.
These findings have cautionary implications for the design of crowdsourcing
competitions.


title:
Dijet azimuthal decorrelations at the LHC in the parton Reggeization
  approach

abstract:
  We study inclusive dijet azimuthal decorrelations in proton-proton collisions
at the CERN LHC invoking the hypothesis of parton Reggeization in t-channel
exchanges at high energies. In the parton Reggeization approach, the main
contribution to the azimuthal angle difference between the two most energetic
jets is due to the Reggeon-Reggeon-Particle-Particle scattering, when the
fusion of two Reggeized gluons into a pair of Yang-Mills gluons dominates.
Using a high-energy factorization scheme with the Kimber-Martin-Ryskin
unintegrated parton distribution functions and the Fadin-Lipatov effective
vertices we obtain good agreement of our calculations with recent measurements
by the ATLAS and CMS Collaborations at the CERN LHC.


title:
Replay Attack Prevention in Kerberos Authentication Protocol Using
  Triple Password

abstract:
  Replay attack and password attacks are serious issues in the Kerberos
authentication protocol. Many ideas have been proposed to prevent these attacks
but they increase complexity of the total Kerberos environment. In this paper
we present an improved method which prevents replay attacks and password
attacks by using Triple password scheme. Three passwords are stored on
Authentication Server and Authentication Server sends two passwords to Ticket
Granting Server (one for Application Server) by encrypting with the secret key
shared between Authentication server and Ticket Granting server.
Similarly,Ticket Granting Server sends one password to Application Server by
encrypting with the secret key shared between TGS and application server.
Meanwhile, Service-Granting-Ticket is transferred to users by encrypting it
with the password that TGS just received from AS. It helps to prevent Replay
attack.


title: 72 DA White Dwarfs Identified in LAMOST Pilot Survey

abstract:
  We present a spectroscopically identified catalogue of 72 DA white dwarfs
from the LAMOST pilot survey. 35 are found to be new identifications after
cross-correlation with the Eisenstein et al. and Villanova catalogues. The
effective temperature and gravity of these white dwarfs are estimated by Balmer
lines fitting. Most of them are hot white dwarfs. The cooling times and masses
of these white dwarfs are estimated by interpolation in theoretical evolution
tracks. The peak of mass distribution is found to be $\sim$ 0.6 $M_\odot$ which
is consistent with prior work in the literature. The distances of these white
dwarfs are estimated using the method of Synthetic Spectral Distances. All of
these WDs are found to be in the Galactic disk from our analysis of space
motions. Our sample supports the expectation white dwarfs with high mass are
concentrated near the plane of Galactic disk


title: Reply to "Comment on Strangeness -2 hypertriton"

abstract:
  In this Reply we argue that the conclusions derived in Ref. arXiv:1301.1241
are questionable.


title: On the Reliability Function of the Discrete Memoryless Relay Channel

abstract:
  Bounds on the reliability function for the discrete memoryless relay channel
are derived using the method of types. Two achievable error exponents are
derived based on partial decode-forward and compress-forward which are
well-known superposition block-Markov coding schemes. The derivations require
combinations of the techniques involved in the proofs of
Csisz\'ar-K\"orner-Marton's packing lemma for the error exponent of channel
coding and Marton's type covering lemma for the error exponent of source coding
with a fidelity criterion. The decode-forward error exponent is evaluated on
Sato's relay channel. From this example, it is noted that to obtain the fastest
possible decay in the error probability for a fixed effective coding rate, one
ought to optimize the number of blocks in the block-Markov coding scheme
assuming the blocklength within each block is large. An upper bound on the
reliability function is also derived using ideas from Haroutunian's lower bound
on the error probability for point-to-point channel coding with feedback.


title:
Global cognitive radio based communication systems: Space-time
  communications

abstract:
  Spectrum Scarcity is a global problem across the world. This paper emphasizes
on the fact that a global problem has to be dealt on global basis, not just
locally by applying the principle of global cognitive radio,Global
Opportunistic Remote Spectrum Access. The Future Internet and Internet of
Things literally scare the communication system designer regarding the
available bandwidth and spectrum resources. There is absolutely no scope to
waste or under utilize the available resources. Hence the proposed idea of
Global Cognitive Radio Concept can undoubtedly solve the resource problems in
next Generation Communications.


title:
Asymptotic Entropy of Random Walks on Regular Languages over a Finite
  Alphabet

abstract:
  We prove existence of asymptotic entropy of random walks on regular languages
over a finite alphabet and we give formulas for it. Furthermore, we show that
the entropy varies real-analytically in terms of probability measures of
constant support, which describe the random walk. This setting applies, in
particular, to random walks on virtually free groups.


title: Interacting growth processes and invariant percolation

abstract:
  The aim of this paper is to underline the relation between reversible growth
processes and invariant percolation. We present two models of interacting
branching random walks (BRWs), truncated BRWs and competing BRWs, where
survival of the growth process can be formulated as the existence of an
infinite cluster in an invariant percolation on a tree. Our approach is fairly
conceptual and allows generalizations to a wider set of "reversible" growth
processes.


title: Survey of Server Virtualization

abstract:
  Virtualization is a term that refers to the abstraction of computer
resources. The purpose of virtual computing environment is to improve resource
utilization by providing a unified integrated operating platform for users and
applications based on aggregation of heterogeneous and autonomous resources.
More recently, virtualization at all levels (system, storage, and network)
became important again as a way to improve system security, reliability and
availability, reduce costs, and provide greater flexibility. Virtualization has
rapidly become a go-to technology for increasing efficiency in the data center.
With virtualization technologies providing tremendous flexibility, even
disparate architectures may be deployed on a single machine without
interference This paper explains the basics of server virtualization and
addresses pros and cons of virtualization


title: Warped Alternatives to Froggatt-Nielsen Models

abstract:
  We consider Randall-Sundrum set up (RS) to be a theory of flavour, as an
alternative to Froggatt-Nielsen models instead of as a solution to the
hierarchy problem. We consider a modified RS framework between the Planck scale
and the GUT scale. This also alleviates constraints from flavour physics.
Fermion masses and mixing angles are fit at the GUT scale. The ranges of the
bulk mass parameters are determined using a $\chi^2$ fit taking in to
consideration the variation in $\mathcal{O}(1)$ parameters. In the hadronic
sector, the heavy top quark requires large bulk mass parameters localising the
right handed top quark close to the IR brane. Two cases of neutrino masses are
considered (a) Planck scale lepton number violation and (b) Dirac neutrino
masses. Contrary to the case of weak scale RS models, both these cases give
reasonable fits to the data, with the Planck scale lepton number violation
fitting slightly better compared to the Dirac case. In the Supersymmetric
version, the fits are not significantly different except for the variation in
$\tan\beta$. If the Higgs superfield and the SUSY breaking spurion are
localized on the same brane then the structure of the sfermion masses are
determined by the profiles of the zero modes of the hypermultiplets in the
bulk. Trilinear terms have the same structure as the Yukawa matrices. The
resultant squark spectrum is around $\sim 2-3 \text{TeV}$ required by the light
Higgs mass to be around 125 GeV and to satisfy the flavour violating
constraints.


title: Sublinear expectation linear regression

abstract:
  Nonlinear expectation, including sublinear expectation as its special case,
is a new and original framework of probability theory and has potential
applications in some scientific fields, especially in finance risk measure and
management. Under the nonlinear expectation framework, however, the related
statistical models and statistical inferences have not yet been well
established. The goal of this paper is to construct the sublinear expectation
regression and investigate its statistical inference. First, a sublinear
expectation linear regression is defined and its identifiability is given.
Then, based on the representation theorem of sublinear expectation and the
newly defined model, several parameter estimations and model predictions are
suggested, the asymptotic normality of estimations and the mini-max property of
predictions are obtained. Furthermore, new methods are developed to realize
variable selection for high-dimensional model. Finally, simulation studies and
a real-life example are carried out to illustrate the new models and
methodologies. All notions and methodologies developed are essentially
different from classical ones and can be thought of as a foundation for general
nonlinear expectation statistics.


title:
Simulation of Obstruction Avoidance Generously Mobility (OAGM) Model
  using Graph-theory Technique

abstract:
  An Obstruction Avoidance Generously Mobility (OAGM) model has been introduced
for controlling ad-hoc sensor networks and thereby operating emerging fields
like military and healthcare services. According to this model, the ability to
send a message to a group of users simultaneously, based solely on their
geographic location, is desirable by using Mission Critical Mobility model that
assumes the obstacle shapes like rectangle or square in the simulation terrain.
The OAGM model is developed by grasping the critical situations of military and
healthcare services by incorporating the node movement model, hierarchical node
organization, placement of obstacle that affect the movement of nodes and also
signal propagation. Graph theory technique is used to find the shortest path of
the node movement process. The varying number of parameter sets with DSR
protocol is analyzed for MCM and OAGM mobility model. The results show OAGM
performance is better than MCM.


title:
Investigation of the dd -> 3He n \pi 0 reaction with the FZ J\"ulich
  WASA-at-COSY facility

abstract:
  An exclusive measurement of the dd -> 3He n \pi 0 reaction was carried at a
beam momentum of p = 1.2 GeV/c using the WASA-at-COSY facility. For the first
time data on the total cross section as well as differential distributions were
obtained. The data are described with a phenomenological approach based on a
combination of a quasi-free model and a partial wave expansion for three-body
reaction. The total cross section is found to be \sigma(tot) = (2.89 +-
0.01(stat) +- 0.06(sys) +- 0.29(norm)) \mu b. The contribution of the
quasi-free processes (with the neutron being target or beam spectator) accounts
for 38% of the total cross section and dominates the differential distributions
in specific regions of the phase space. The remaining part of the cross section
can be described within a partial wave decomposition indicating the
significance of p-wave contributions in the final state.


title: A compared analysis of the susceptibility in the O(N) theory

abstract:
  The longitudinal susceptibility $\chi_L$ of the O(N) theory in the broken
phase is analyzed by means of three different approaches, namely the leading
contribution of the 1/N expansion, the Functional Renormalization Group flow in
the Local Potential approximation and the improved effective potential via the
Callan-Symanzik equations, properly extended to $d=4$ dimensions through the
expansion in powers of $\epsilon=4-d$. The findings of the three approaches are
compared and their agreement in the large $N$ limit is shown. The numerical
analysis of the Functional Renormalization Group flow equations at small $N$
supports the vanishing of $\chi_L^{-1}$ in $d=3$ and $d=3.5$ but is not
conclusive in $d=4$, where we have to resort to the Callan-Smanzik approach. At
finite $N$ as well as in the limit $N\to\infty$, we find that $\chi^{-1}_L$
vanishes with $J$ as $J^{\epsilon/2}$ for $\epsilon>0$ and as $(\ln (J))^{-1}$
in $d=4$.


title: Data, text and web mining for business intelligence: a survey

abstract:
  The Information and Communication Technologies revolution brought a digital
world with huge amounts of data available. Enterprises use mining technologies
to search vast amounts of data for vital insight and knowledge. Mining tools
such as data mining, text mining, and web mining are used to find hidden
knowledge in large databases or the Internet.


title:
Slippage effect on laser phase error amplification in seeded harmonic
  generation free-electron lasers

abstract:
  Free-electron lasers (FELs) seeded with external lasers hold great promise
for generating high power radiation with nearly transform-limited bandwidth in
soft x-ray region. However, it has been pointed out that the initial seed laser
noise will be amplified by the frequency up-conversion process, which may
degrade the quality of the output radiation produced by a harmonic generation
scheme. In this paper, theoretical and simulation studies for laser phase error
amplification in seeded FEL schemes with slippage effect taken into account are
presented. It is found that, the seed laser imperfection experienced by the
electron beam can be significantly smoothed by the slippage effect in the
modulator when the slippage length is comparable to the laser pulse length.
This smoothing effect allows one to preserve the excellent temporal coherence
of seeded FELs in presence of large laser phase errors. For ultra-short UV seed
lasers with FWHM around 16 fs, the slippage length in a modulator with ~30
undulator periods is typically comparable to the laser width; for longer seed
laser pulses with FWHM around 80 fs, the slippage length can be made comparable
to the laser width using a modulator tuned at the sub-harmonic of the UV seed
laser. Three-dimensional simulations have been carried out for a soft x-ray
facility using seed laser pulses with large frequency chirp and the results
show that the sensitivity of the bandwidth of the seeded FEL to the initial
frequency chirp can be significantly reduced by a proper design of the
modulator such that the slippage length is comparable to the laser width. Our
studies show that the tolerance on laser phase error for generating nearly
transform-limited soft x-ray pulses in seeded FELs is much looser than
previously thought and fully coherent radiation at nanometer wavelength may be
reached with current technologies.


title:
Effects of excess or deficiency of oxygen content on the electronic
  structure of high-$T_C$ cuprates

abstract:
  Band structure calculations are presented for large supercells of
Ba$_2$CuO$_4$ (BCO) with O-vacancies in planar or apic al positions, and of
superoxygenated La$_2$CuO$_4$ (LCO) with oxygen interstitials in the
La$_2$O$_2$ layers. It is foun d that apical oxygen vacancies in BCO act as
electron dopants and makes the electronic structure similar to that of hole
doped LCO. Excess oxygen interstitials forming wires in the La$_2$O$_2$ layers
of LCO are shown to yield a much larger density-of-states at the Fermi energy
than for the stoichiometric compound related with a segmentation of the Fermi
surface. Anti-ferromagnetic (AFM) spin fluctuations are strengthened by
O-vacancies in BCO as well as by oxygen interstitials in LCO, but are strongly
suppressed in O-deficient LCO. Our results indicate the complexity of doping by
O-vacancies, and by ordered defects that are a significant factor contr olling
the electronic properties of cuprates.


title: Imprints of superfluidity on magneto-elastic QPOs of SGRs

abstract:
  Our numerical simulations show that axisymmetric, torsional, magneto-elastic
oscillations of magnetars with a superfluid core can explain the whole range of
observed quasi-periodic oscillations (QPOs) in the giant flares of soft
gamma-ray repeaters. There exist constant phase, magneto-elastic QPOs at both
low (f<150 Hz) and high frequencies (f>500 Hz), in full agreement with
observations. The range of magnetic field strengths required to match the
observed QPO frequencies agrees with that from spin-down estimates. These
results strongly suggest that neutrons in magnetar cores are superfluid.


title: Growth of balls in the universal cover of surfaces and graphs

abstract:
  In this paper, we prove uniform lower bounds on the volume growth of balls in
the universal covers of Riemannian surfaces and graphs. More precisely, there
exists a constant $\delta>0$ such that if $(M,hyp)$ is a closed hyperbolic
surface and $h$ another metric on $M$ with $\area(M,h)\leq \delta \area(M,hyp)$
then for every radius $R\geq 1$ the universal cover of $(M,h)$ contains an
$R$-ball with area at least the area of an $R$-ball in the hyperbolic plane.
This positively answers a question of L. Guth for surfaces. We also prove an
analog theorem for graphs.


title: Distributed dictionary learning over a sensor network

abstract:
  We consider the problem of distributed dictionary learning, where a set of
nodes is required to collectively learn a common dictionary from noisy
measurements. This approach may be useful in several contexts including sensor
networks. Diffusion cooperation schemes have been proposed to solve the
distributed linear regression problem. In this work we focus on a
diffusion-based adaptive dictionary learning strategy: each node records
observations and cooperates with its neighbors by sharing its local dictionary.
The resulting algorithm corresponds to a distributed block coordinate descent
(alternate optimization). Beyond dictionary learning, this strategy could be
adapted to many matrix factorization problems and generalized to various
settings. This article presents our approach and illustrates its efficiency on
some numerical examples.


title: Statistical mechanics of bent twisted ribbons

abstract:
  We present an analytical study of bent twisted ribbons. We first describe the
elastic response of a ribbon within a purely mechanical framework. We then
study the role of thermal fluctuations in modifying its elastic response. We
predict the moment angle relation of bent and twisted ribbons. Such a study is
expected to shed light on the role of twist in the "J factor" for DNA looping
and on bending elasticity of twisted graphene ribbons.


title:
Global dynamics below the ground state energy for the
  Klein-Gordon-Zakharov system in the 3D radial case

abstract:
  We consider the global dynamics below the ground state energy for the
Klein-Gordon-Zakharov system in the 3D radial case; and obtain the dichotomy
between scattering and finite time blow up.


title: Kinetic mechanism of chain folding in polymer crystallization

abstract:
  I develop a kinetic mechanism to explain chain folding in polymer
crystallization which is based on the competition between the formation of
stems, which is due to frequent occupations of trans states along the chains in
the supercooled polymer melt, and the random coil structure of the polymer
chains. Setting equal the average formation time of stems of length $% d_l$
with the Rouse time of a piece of polymer of the same arc length $d_l$ yields a
lower bound for the thickness of stems and bundles. The estimated lamellar
thickness is inversely proportional to the supercooling. The present approach
emphasizes the importance of repulsive interactions in polymer crystallization,
which are expected to be responsible for the logarithmic lamellar thickening
and the increase of lamellar thickness with pressure. An expression for the
growth rate is derived by considering the growth as a dynamic multistage
process.


title: A New Paradigm to Half-Metallicity in Graphene Nanoribbons

abstract:
  In contrast to the well recognized transverse-electric-field-induced
half-metallicity in zigzag graphene nanoribbons, here we demonstrate by
first-principles calculations that zigzag graphene nanoribbons sandwiched
between hexagonal boron nitride nanoribbons or sheets can be tuned into
half-metal simply by a bias voltage or a moderate compressive strain. The
half-metallicity is attributed to an enhanced coupling effect of spontaneous
polarization and asymmetrical exchange correlation along the ribbon width. The
findings should open a viable route for efficient spin-resolved band
engineering in graphene based devices that are compatible with the current
technology of semiconductor industry.


title: Astronomical Image Denoising Using Dictionary Learning

abstract:
  Astronomical images suffer a constant presence of multiple defects that are
consequences of the intrinsic properties of the acquisition equipments, and
atmospheric conditions. One of the most frequent defects in astronomical
imaging is the presence of additive noise which makes a denoising step
mandatory before processing data. During the last decade, a particular modeling
scheme, based on sparse representations, has drawn the attention of an ever
growing community of researchers. Sparse representations offer a promising
framework to many image and signal processing tasks, especially denoising and
restoration applications. At first, the harmonics, wavelets, and similar bases
and overcomplete representations have been considered as candidate domains to
seek the sparsest representation. A new generation of algorithms, based on
data-driven dictionaries, evolved rapidly and compete now with the
off-the-shelf fixed dictionaries. While designing a dictionary beforehand leans
on a guess of the most appropriate representative elementary forms and
functions, the dictionary learning framework offers to construct the dictionary
upon the data themselves, which provides us with a more flexible setup to
sparse modeling and allows to build more sophisticated dictionaries. In this
paper, we introduce the Centered Dictionary Learning (CDL) method and we study
its performances for astronomical image denoising. We show how CDL outperforms
wavelet or classic dictionary learning denoising techniques on astronomical
images, and we give a comparison of the effect of these different algorithms on
the photometry of the denoised images.


title: Hedging of Game Options under Model Uncertainty in Discrete Time

abstract:
  We introduce a setup of model uncertainty in discrete time. In this setup we
derive dual expressions for the super--replication prices of game options with
upper semicontinuous payoffs. We show that the super--replication price is
equal to the supremum over a special (non dominated) set of martingale
measures, of the corresponding Dynkin games values. This type of results is
also new for American options.


title: A New Result on the Origin of the Extragalactic Gamma-ray Background

abstract:
  In the paper, we continually use the method of image stacking to study the
origin of the extragalactic gamma-ray background (EGB) at GeV bands, and find
that the Faint Images of the Radio Sky at Twenty centimeters (FIRST) sources
undetected by the Large Area Telescope on the Fermi Gamma-ray Space Telescope
can contribute about (56{plus minus}6)% of the EGB. Because the FIRST is a flux
limited sample of radio sources with incompleteness at the faint limit, we
consider that the point-sources, including blazars, non-blazar AGNs,starburst
galaxies, could produce a much larger fraction of the EGB.


title:
Greatest solutions and differential inequalities: a journey in two
  directions

abstract:
  We present a new elementary proof of the existence of the least and the
greatest solutions to initial value problems in the conditions of Peano's
existence theorem. Our proof is based on a modification of Perron's method
which allows us to obtain quite easily the greatest solution as the solution
with biggest possible integral. In doing so, we simplify the usual proofs,
technically overloaded with lower (upper) solutions and/or related differential
inequalities. Moreover, those differential (and integral) inequalities, which
are interesting in their own right, can be quickly proven by means of known
techniques once we know that the greatest and the least solutions exist.
Summing up, we revert the usual approach from differential inequalities to
extreme solutions, getting a somewhat smoother presentation.


title:
Identifying cancer subtypes in glioblastoma by combining genomic,
  transcriptomic and epigenomic data

abstract:
  We present a nonparametric Bayesian method for disease subtype discovery in
multi-dimensional cancer data. Our method can simultaneously analyse a wide
range of data types, allowing for both agreement and disagreement between their
underlying clustering structure. It includes feature selection and infers the
most likely number of disease subtypes, given the data.
  We apply the method to 277 glioblastoma samples from The Cancer Genome Atlas,
for which there are gene expression, copy number variation, methylation and
microRNA data. We identify 8 distinct consensus subtypes and study their
prognostic value for death, new tumour events, progression and recurrence. The
consensus subtypes are prognostic of tumour recurrence (log-rank p-value of
$3.6 \times 10^{-4}$ after correction for multiple hypothesis tests). This is
driven principally by the methylation data (log-rank p-value of $2.0 \times
10^{-3}$) but the effect is strengthened by the other 3 data types,
demonstrating the value of integrating multiple data types.
  Of particular note is a subtype of 47 patients characterised by very low
levels of methylation. This subtype has very low rates of tumour recurrence and
no new events in 10 years of follow up. We also identify a small gene
expression subtype of 6 patients that shows particularly poor survival
outcomes. Additionally, we note a consensus subtype that showly a highly
distinctive data signature and suggest that it is therefore a biologically
distinct subtype of glioblastoma.
  The code is available from https://sites.google.com/site/multipledatafusion/


title:
On the Solution of General Impulse Control Problems Using Superharmonic
  Functions

abstract:
  In this paper, a characterization of the solution of impulse control problems
in terms of superharmonic functions is given. In a general Markovian framework,
the value function of the impulse control problem is shown to be the minimal
function in a convex set of superharmonic functions. This characterization also
leads to optimal impulse control strategies and can be seen as the
corresponding characterization to the description of the value function for
optimal stopping problems as a smallest superharmonic majorant of the reward
function. The results are illustrated with examples from different fields,
including multiple stopping and optimal switching problems.


title: Bell Soliton in Ultra-cold Atomic Fermi Gas

abstract:
  We demonstrate the existence of supersonic bell soliton in the
Bardeen-Cooper-Schrieffer-Bose-Einstein condensate (BCS-BEC) crossover regime.
Starting from the extended Thomas-Fermi density functional theory of superfluid
order parameter, a density transformation is used to map the hydrodynamic mean
field equation to a Lienard type equation. As a result, bell solitons are
obtained as exact solutions, which is further verified by the numerical
solution of the dynamical equation. The stability of the soliton is established
and its behaviour in the entire crossover domain is obtained. It is found that,
akin to the case of vortices, the bell solitons yield highest contrast in the
BEC regime.


title: Random lasing in structures with multi-scale transport properties

abstract:
  In a random laser (RL), a system possessing in itself both resonator and
amplifying medium while lacking of a macroscopic cavity, the feedback is
provided by the scattering, which forces light to travel across very long
random paths. Here we demonstrate that RL properties may be tuned by the
topology of the scattering system retaining unchanged scattering strength and
gain efficiency. This is possible in a system based on sparse clusters,
possessing two relevant structural lengths: the macroscopic inter cluster
separation and the mesoscopic intra-cluster mean free path.


title:
Exploring the Bonding of Large Hydrocarbons on Noble Metals:
  Diindoperylene on Cu(111), Ag(111), and Au(111)

abstract:
  We present a benchmark study for the adsorption of a large pi-conjugated
organic molecule on different noble metal surfaces, which is based on X-ray
standing wave (XSW) measurements and density functional theory calculations
with van der Waals (vdW) interactions. The bonding distances of
diindenoperylene on Cu(111), Ag(111), and Au(111) surfaces (2.51 A, 3.01 A, and
3.10 A, respectively) determined with the normal incidence XSW technique are
compared with calculations. Excellent agreement with the experimental data,
i.e. deviations less than 0.1 A, is achieved using the Perdew-Burke-Ernzerhof
functional with vdW interactions that include the collective response of
substrate electrons (PBE+vdW^{surf} method). Noteworthy, the calculations show
that the vdW contribution to the adsorption energy increases in the order
Au(111) < Ag(111) < Cu(111).


title: Chaos in circuit QED: decoherence, localization, and nonclassicality

abstract:
  We study the open system dynamics of a circuit QED model operating in the
ultrastrong coupling regime. If the resonator is pumped periodically in time
the underlying classical system is chaotic. Indeed, the periodically driven
Jaynes-Cummings model in the Born-Oppenheimer approximation resembles a Duffing
oscillator which in the classical limit is a well-known example of a chaotic
system. Detection of the field quadrature of the output field acts as an
effective position measurement of the oscillator. We address how such detection
affects the quantum chaotic evolution in this bipartite system. We
differentiate between single measurement realizations and ensembles of repeated
measurements. In the former case a measurement/decoherence induced localization
effect is encountered, while in the latter this localization is almost
completely absent. This is in marked contrast to numerous earlier works
discussing the quantum-classical correspondence in measured chaotic systems.
This lack of a classical correspondence under relatively strong measurement
induced decoherence is attributed to the inherent quantum nature of the qubit
subsystem and in particular to the quantum correlations between the qubit and
the field which persist despite the decoherence.


title: Collapse of random triangular groups: a closer look

abstract:
  The random triangular group \Gamma(n,t) is a group given by a presentation
P=<S|R>, where S is a set of n generators and R is a random set of t cyclically
reduced words of length three. The asymptotic behavior of \Gamma(n,t) is in
some respects similar to that of widely studied density random group introduced
by Gromov. In particular, it is known that if t <= n^{3/2-\epsilon} for some
\epsilon > 0, then with probability 1-o(1) \Gamma(n,t) is infinite and
hyperbolic, while for t >= n^{3/2+\epsilon}, with probability 1-o(1) it is
trivial. In this note we show that \Gamma(n,t) collapses provided only that t
<= C n^{3/2} for some constant C>0.


title: Accurate effective Hamiltonians via unitary flow in Floquet space

abstract:
  We present a systematic construction of effective Hamiltonians of
periodically driven quantum systems. Because of an equivalence between the time
dependence of a Hamiltonian and an interaction in its Floquet operator, flow
equations, that permit to decouple interacting quantum systems, allow us to
identify time-independent Hamiltonians for driven systems. With this approach,
we explain the experimentally observed deviation of expected suppression of
tunneling in ultracold atoms.


title: Integrability vs Quantum Thermalization

abstract:
  Non-integrability is often taken as a prerequisite for quantum
thermalization. Still, a generally accepted definition of quantum integrability
is lacking. With the basis in the driven Rabi model we discuss this careless
usage of the term "integrability" in connection to quantum thermalization. The
model would be classified as non-integrable according to the most commonly used
definitions, for example, the only preserved quantity is the total energy.
Despite this fact, a thorough analysis conjectures that the system will not
thermalize. Thus, our findings suggest first of all (i) that care should be
paid when linking non-integrability with thermalization, and secondly (ii) that
the standardly used definitions for quantum integrability are unsatisfactory.


title:
Vector modulational instability induced by parametric resonance in
  periodically tapered highly-birefringent optical fibers

abstract:
  We study the modulational instability induced by periodic variations of
group-velocity dispersion and nonlinear coefficients in a highly birefringent
fiber. We observe, for each resonance order, the presence of two pairs of
genuine vector type sidebands, which are spectrally unbalanced between the
polarization components for nonzero group-index mismatch, and one pair of
balanced sidebands emerging and dominating at increasing group-index mismatch.
As the conventional modulational instability manifests itself, it is partially
suppressed by the proximity of these new unstable regions.


title: 0-1 sequences of the Thue-Morse type and Sarnak's conjecture

abstract:
  We show that the images via $z\mapsto z^m$ of the continuous part of the
spectral measures of the dynamical systems generated by the 0-1 sequences of
the Thue-Morse type are pairwise mutually singular for different odd numbers
$m\in\N$. Sarnak's conjecture on orthogonality with the M\"obius function is
shown to hold for such dynamical systems. The same conjecture is shown to hold
for all systems induced by regular Toeplitz sequences. A non-regular Toeplitz
sequence for which Sarnak's conjecture fails is constructed.


title: Characteristic classes in $TMF$ of level $\Gamma_1(3)$

abstract:
  Let $TMF_1(n)$ be the spectrum of topological modular forms equipped with a
$\Gamma_1(n)$-structure. We compute the $K(2)$-local $TMF_1(3)$-cohomology of
$B{\mathit String}$ and $B{\mathit Spin}$: both are power series rings freely
generated by classes that we explicitly construct and which generalize the
classical Pontryagin classes. As a first application of this computation, we
show how to construct $TMF(3n)$-cohomology classes from stable positive energy
representations of the loop groups $L{\mathit Spin}$.


title: Tutorial for Bayesian forensic likelihood ratio

abstract:
  In the Bayesian paradigm for presenting forensic evidence to court, it is
recommended that the weight of the evidence be summarized as a likelihood ratio
(LR) between two opposing hypotheses of how the evidence could have been
produced. Such LRs are necessarily based on probabilistic models, the
parameters of which may be uncertain. It has been suggested by some authors
that the value of the LR, being a function of the model parameters should
therefore also be considered uncertain and that this uncertainty should be
communicated to the court. In this tutorial, we consider a simple example of a
'fully Bayesian' solution, where model uncertainty is integrated out to produce
a value for the LR which is not uncertain. We show that this solution agrees
with common sense. In particular, the LR magnitude is a function of the amount
of data that is available to estimate the model parameters.


title:
Effect of Vacuum Annealing on Superconductivity in Fe(Se,Te) Single
  Crystals

abstract:
  The effect of vacuum annealing on superconductivity is investigated in
Fe(Se,Te) single crystals. It is found that superconductivity is not enhanced
by annealing under high vacuum (~ 10^(-3) Pa) or by annealing in a sealed
evacuated quartz tube. In a moderate vacuum atmosphere (~ 1 Pa), iron oxide
layers are found to show up on sample surfaces, which would draw excess Fe out
of the crystal. Thus, it is suggested that remanent oxygen effectively works to
remove excess Fe from the matrix of Fe(Se,Te) crystals, resulting improvement
of superconducting transition temperature. Our transport measurements suggest
that the excess Fe scatters the carriers on electron- and hole-type channels in
a different manner. We discuss how the mobility of two types of carriers
correlate with superconductivity. Since both the electron and hole bands are
important for the occurrence of superconductivity, excess Fe would suppress
superconductivity mainly due to strong scattering of electrons.


title:
Refined form of the paper "Canonical formalism of the f(R)-type gravity
  in terms of Lie derivatives"

abstract:
  We refine the presentation of the previous paper of our group, Y.Ezawa et
al., Class. Quantum Grav. {\bf 23} (2006), 3205 [arXiv:gr-qc/0507060]. In that
paper, we proposed a canonical formalism of f(R)-type generalized gravity by
using the Lie derivatives instead of the time derivatives. However, the use of
the Lie derivatives was not sufficient. In this note, we make use of the Lie
derivatives as far as possible, so that no time derivatives are used.


title: Adjunctions and Braided Objects

abstract:
  In this paper we investigate the categories of braided objects, algebras and
bialgebras in a given monoidal category, some pairs of adjoint functors between
them and their relations. In particular we construct a braided primitive
functor and its left adjoint, the braided tensor bialgebra functor, from the
category of braided objects to the one of braided bialgebras. The latter is
obtained by a specific elaborated construction introducing a braided tensor
algebra functor as a left adjoint of the forgetful functor from the category of
braided algebras to the one of braided objects. The behaviour of these functors
in the case when the base category is braided is also considered.


title: Singularities and Quinn spectra

abstract:
  We introduce singularities to Quinn spectra. It enables us to talk about ads
with prescribed singularities and to explicitly construct representatives for
prominent spectra like Morava $K$-theories or for $L$-theory with
singularities. We develop a spectral sequence for the computation of the
associated bordism groups and investigate product structures in the presence of
singularities.


title: Can LHC observe an anomaly in ttZ production?

abstract:
  The cross section for production at the 7 TeV LHC has been measured. For the
first time it therefore becomes possible to measure Z couplings to top quarks.
Interpreting the notorious LEP1 anomaly on Z couplings to b quarks in terms of
an extra-dimension model, one expects an excess, as large as a factor 2, on the
rate which may already become significant with the LHC at 8 TeV data. Other
schemes are reviewed which also predict deviations of couplings. The size of
the effect and a dramatic increase of the top quarks with the right chirality
should confirm our interpretation of the underlying mechanism. Complementary
signals observable at LHC are also briefly reviewed.


title:
Intertwining relations for one-dimensional diffusions and application to
  functional inequalities

abstract:
  Following the recent work [13] fulfilled in the discrete case, we pro- vide
in this paper new intertwining relations for semigroups of one-dimensional
diffusions. Various applications of these results are investigated, among them
the famous variational formula of the spectral gap derived by Chen and Wang
[15] together with a new criterion ensuring that the logarithmic Sobolev
inequality holds. We complete this work by revisiting some classical examples,
for which new estimates on the optimal constants are derived.


title:
Formal Verification of a C Value Analysis Based on Abstract
  Interpretation

abstract:
  Static analyzers based on abstract interpretation are complex pieces of
software implementing delicate algorithms. Even if static analysis techniques
are well understood, their implementation on real languages is still
error-prone. This paper presents a formal verification using the Coq proof
assistant: a formalization of a value analysis (based on abstract
interpretation), and a soundness proof of the value analysis. The formalization
relies on generic interfaces. The mechanized proof is facilitated by a
translation validation of a Bourdoncle fixpoint iterator. The work has been
integrated into the CompCert verified C-compiler. Our verified analysis
directly operates over an intermediate language of the compiler having the same
expressiveness as C. The automatic extraction of our value analysis into OCaml
yields a program with competitive results, obtained from experiments on a
number of benchmarks and comparisons with the Frama-C tool.


title:
Percolation on interdependent networks with a fraction of antagonistic
  interactions

abstract:
  Recently, the percolation transition has been characterized on interacting
networks both in presence of interdependent and antagonistic interactions. Here
we characterize the phase diagram of the percolation transition in two Poisson
interdependent networks with a percentage q of antagonistic nodes. We show that
this system can present a bistability of the steady state solutions, and both
first, and second order phase transitions. In particular, we observe a
bistability of the solutions in some regions of the phase space also for a
small fraction of antagonistic interactions 0<q<0.4. Moreover, we show that a
fraction q>q_c=2/3 of antagonistic interactions is necessary to strongly reduce
the region in phase-space in which both networks are percolating. This last
result suggests that interdependent networks are robust to the presence of
antagonistic interactions. Our approach can be extended to multiple networks,
and to complex boolean rules for regulating the percolation phase transition.


title: Bell tests with min-entropy sources

abstract:
  Device independent protocols rely on the violation of Bell inequalities to
certify properties of the resources available. The violation of the
inequalities are meaningless without a few well-known assumptions. One of these
is measurement independence, the property that the source of the states
measured in an inequality is uncorrelated from the measurements selected. Since
this assumption cannot be confirmed, we consider the consequences of relaxing
it and find that the definition chosen is critically important to the observed
behavior. Considering a definition that is a bound on the min-entropy of the
measurement settings, we find lower bounds on the min-entropy of the seed used
to choose the inputs required to deduce any quantum or non-local behavior from
a Bell inequality violation. These bounds are significantly more restrictive
than the ones obtained by endowing the seed with the further structure of a
Santha-Vazirani source. We also outline a procedure for finding tight bounds
and study the set of probabilities that can result from relaxing measurement
dependence.


title: Transfinite Adams representability

abstract:
  In a well generated triangulated category T, given a regular cardinal a, we
consider the following problems: given a functor from the category of a-compact
objects to abelian groups that preserves products of <a objects and takes exact
triangles to exact sequences, is it the restriction of a representable functor
in T? Is every natural transformation between two such restricted representable
functors induced by a map between the representatives? If the answer to both
questions is positive we say that T satisfies a-Adams representability. A
classical result going back to Brown and Adams shows that the stable homotopy
category satisfies Adams representability for the first infinite cardinal. For
that cardinal, Adams representability is well understood thanks to the work of
Christensen, Keller and Neeman. In this paper, we develop an obstruction theory
to decide when T satisfies a-Adams representability. We derive necessary and
sufficient conditions of homological nature, and we compute several examples.
In particular, we show that there are rings satisfying a-Adams representability
for all non-countable cardinals a and rings which do not satisfy a-Adams
representability for any infinite cardinal a. Moreover, we exhibit rings for
which the answer to both questions is no for infinite many cardinals. As a side
result, we give an example of an infinite phantom map.


title: A notion of graph likelihood and an infinite monkey theorem

abstract:
  We play with a graph-theoretic analogue of the folklore infinite monkey
theorem. We define a notion of graph likelihood as the probability that a given
graph is constructed by a monkey in a number of time steps equal to the number
of vertices. We present an algorithm to compute this graph invariant and closed
formulas for some infinite classes. We have to leave the computational
complexity of the likelihood as an open problem.


title:
Helical Fermi arcs and surface states in time-reversal invariant Weyl
  semimetals

abstract:
  Weyl semimetals are gapless three-dimensional topological materials where two
bands touch at even number of points in the Brillouin zone. In this work we
study a zincblende lattice model realizing a time-reversal invariant Weyl
semimetal. The bulk dynamics is decribed by twelve helical Weyl nodes. Surface
states form a peculiar quasi two-dimensional helical metal fundamentally
different from the Dirac form typical for topological insulators. Allowed
direction of velocity and spin of low-energy surface excitations are locked to
the cubic symmetry axes. The studied system illustrates general properties of
surface states in systems with common crystal symmetries.


title: An age structured demographic theory of technological change

abstract:
  At the heart of technology transitions lie complex processes of social and
industrial dynamics. The quantitative study of sustainability transitions
requires modelling work, which necessitates a theory of technology
substitution. Many, if not most, contemporary modelling approaches for future
technology pathways overlook most aspects of transitions theory, for instance
dimensions of heterogenous investor choices, dynamic rates of diffusion and the
profile of transitions. A significant body of literature however exists that
demonstrates how transitions follow S-shaped diffusion curves or Lotka-Volterra
systems of equations. This framework is used ex-post since timescales can only
be reliably obtained in cases where the transitions have already occurred,
precluding its use for studying cases of interest where nascent innovations in
protective niches await favourable conditions for their diffusion. In
principle, scaling parameters of transitions can, however, be derived from
knowledge of industrial dynamics, technology turnover rates and technology
characteristics. In this context, this paper presents a theory framework for
evaluating the parameterisation of S-shaped diffusion curves for use in
simulation models of technology transitions without the involvement of
historical data fitting, making use of standard demography theory applied to
technology at the unit level. The classic Lotka-Volterra competition system
emerges from first principles from demography theory, its timescales explained
in terms of technology lifetimes and industrial dynamics. The theory is placed
in the context of the multi-level perspective on technology transitions, where
innovation and the diffusion of new socio-technical regimes take a prominent
place, as well as discrete choice theory, the primary theoretical framework for
introducing agent diversity.


title: SCAF An effective approach to Classify Subspace Clustering algorithms

abstract:
  Subspace clustering discovers the clusters embedded in multiple, overlapping
subspaces of high dimensional data. Many significant subspace clustering
algorithms exist, each having different characteristics caused by the use of
different techniques, assumptions, heuristics used etc. A comprehensive
classification scheme is essential which will consider all such characteristics
to divide subspace clustering approaches in various families. The algorithms
belonging to same family will satisfy common characteristics. Such a
categorization will help future developers to better understand the quality
criteria to be used and similar algorithms to be used to compare results with
their proposed clustering algorithms. In this paper, we first proposed the
concept of SCAF (Subspace Clustering Algorithms Family). Characteristics of
SCAF will be based on the classes such as cluster orientation, overlap of
dimensions etc. As an illustration, we further provided a comprehensive,
systematic description and comparison of few significant algorithms belonging
to 'Axis parallel, overlapping, density based' SCAF.


title: On Model-Based RIP-1 Matrices

abstract:
  The Restricted Isometry Property (RIP) is a fundamental property of a matrix
enabling sparse recovery. Informally, an m x n matrix satisfies RIP of order k
in the l_p norm if ||Ax||_p \approx ||x||_p for any vector x that is k-sparse,
i.e., that has at most k non-zeros. The minimal number of rows m necessary for
the property to hold has been extensively investigated, and tight bounds are
known. Motivated by signal processing models, a recent work of Baraniuk et al
has generalized this notion to the case where the support of x must belong to a
given model, i.e., a given family of supports. This more general notion is much
less understood, especially for norms other than l_2. In this paper we present
tight bounds for the model-based RIP property in the l_1 norm. Our bounds hold
for the two most frequently investigated models: tree-sparsity and
block-sparsity. We also show implications of our results to sparse recovery
problems.


title:
Fingerprinting Rotons in a Dipolar Condensate: Super-Poissonian Peak in
  the Atom-Number Fluctuations

abstract:
  We demonstrate that measurements of atom-number fluctuations in a trapped
dipolar condensate can reveal the presence of the elusive roton excitation. The
key signature is a super-Poissonian peak in the fluctuations as the size of the
measurement cell is varied, with the maximum occurring when the size is
comparable to the roton wavelength. The magnitude of this roton feature is
enhanced with temperature. The variation in fluctuations across the condensate
demonstrates that the roton excitations are effectively confined to propagate
in the densest central region, realizing a density trapped roton gas. While our
main results are based on full numerical solutions of the meanfield equations,
we also develop and validate a simple local density theory. Finally, we
consider fluctuations measured within a washer-shaped cell which filters out
the contribution of modes with nonzero angular momentum and provides a signal
sensitive to individual roton modes.


title:
On compactness of logics that can express properties of symmetry or
  connectivity

abstract:
  A condition, in two variants, is given such that if a property P satisfies
this condition, then every logic which is at least as strong as first-order
logic and can express P fails to have the compactness property. The result is
used to prove that for a number of natural properties P speaking about
automorphism groups or connectivity, every logic which is at least as strong as
first-order logic and can express P fails to have the compactness property. We
also give an example of a logic that extends first-order logic, has the
compactness property and can express the property "the cardinality of the
automorphism group is at most $2^{\aleph_0}$".


title:
Ghosts in pure and hybrid formalisms of gravity theories: a unified
  analysis

abstract:
  In the first order formalism of gravitational theories, the spacetime
connection is considered as an independent variable to vary together with the
metric. However, the metric still generates its Levi-Civita connection that
turns out to determine the geodesics of matter. Recently, "hybrid" gravity
theories have been introduced by constructing actions involving both the
independent Palatini connection and the metric Levi-Civita connection. In this
study a method is developed to analyse the field content of such theories, in
particular to determine whether the propagating degrees of freedom are ghosts
or tachyons. New types of second, fourth and sixth order derivative gravity
theories are investigated and the so called f(X) theories are singled out as a
viable class of "hybrid" extensions of General Relativity.


title: Individual Differences in Structural Equation Model Parameters

abstract:
  Individuals may differ in their parameter values. This article discusses a
three-step method of studying such differences by calculating and then modeling
"individual parameter contributions", making the study of heterogeneity in
arbitrary structural equation model parameters as technically challenging as
performing linear regression. The proposed approach allows for a contribution
to the study of differential error variances in survey methodology that would
have been difficult to make otherwise.


title: A partially dimensionally-split approach to numerical MHD

abstract:
  We modify an existing magnetohydrodynamics algorithm to make it more
compatible with a dimensionally-split (DS) framework. It is based on the
standard reconstruct-solve-average strategy (using a Riemann solver), and
relies on constrained transport to ensure that the magnetic field remains
divergence-free (div B = 0). The DS approach, combined with the use of a
single, cell-centred grid (for both the fluid quantities and the magnetic
field), means that the algorithm can be easily added to existing DS
hydrodynamics codes. This makes it particularly useful for mature astrophysical
codes, which often model more complicated physical effects on top of an
underlying DS hydrodynamics engine, and therefore cannot be restructured
easily. Several test problems have been included to demonstrate the accuracy of
the algorithm, and illustrative source code has been made freely available
online.


title: Modified Soft Brood Crossover in Genetic Programming

abstract:
  Premature convergence is one of the important issues while using Genetic
Programming for data modeling. It can be avoided by improving population
diversity. Intelligent genetic operators can help to improve the population
diversity. Crossover is an important operator in Genetic Programming. So, we
have analyzed number of intelligent crossover operators and proposed an
algorithm with the modification of soft brood crossover operator. It will help
to improve the population diversity and reduce the premature convergence. We
have performed experiments on three different symbolic regression problems.
Then we made the performance comparison of our proposed crossover (Modified
Soft Brood Crossover) with the existing soft brood crossover and subtree
crossover operators.


title:
Green Rings of Finite Dimensional Pointed Rank One Hopf algebras of
  Nilpotent Type

abstract:
  Let $H$ be a finite dimensional pointed rank one Hopf algebra of nilpotent
type. We first determine all finite dimensional indecomposable $H$-modules up
to isomorphism, and then establish the Clebsch-Gordan formulas for the
decompositions of the tensor products of indecomposable $H$-modules by virtue
of almost split sequences. The Green ring $r(H)$ of $H$ will be presented in
terms of generators and relations. It turns out that the Green ring $r(H)$ is
commutative and is generated by one variable over the Grothendieck ring
$G_0(H)$ of $H$ modulo one relation. Moreover, $r(H)$ is Frobenius and
symmetric with dual bases associated to almost split sequences, and its
Jacobson radical is a principal ideal. Finally, we show that the stable Green
ring, the Green ring of the stable module category, is isomorphic to the
quotient ring of $r(H)$ modulo the principal ideal generated by the projective
cover of the trivial module. It turns out that the complexified stable Green
algebra is a group-like algebra and hence a bi-Frobenius algebra.


title: A Novel Metaheuristics To Solve Mixed Shop Scheduling Problems

abstract:
  This paper represents the metaheuristics proposed for solving a class of Shop
Scheduling problem. The Bacterial Foraging Optimization algorithm is featured
with Ant Colony Optimization algorithm and proposed as a natural inspired
computing approach to solve the Mixed Shop Scheduling problem. The Mixed Shop
is the combination of Job Shop, Flow Shop and Open Shop scheduling problems.
The sample instances for all mentioned Shop problems are used as test data and
Mixed Shop survive its computational complexity to minimize the makespan. The
computational results show that the proposed algorithm is gentler to solve and
performs better than the existing algorithms.


title: Decomposition into two trees with orientation constraints

abstract:
  We prove that deciding whether the edge set of a graph can be partitionned
into two spanning trees with orientation constraints is NP-complete. If P
$\neq$ NP then this disproves a conjecture of Recski.


title:
Radiation Hardness of Graphene and MoS2 Field Effect Devices Against
  Swift Heavy Ion Irradiation

abstract:
  We have investigated the deterioration of field effect transistors based on
twodimensional materials due to irradiation with swift heavy ions. Devices were
prepared with exfoliated single layers of MoS2 and graphene, respectively. They
were characterized before and after irradiation with 1.14 GeV U228+2 ions using
three different fluences. By electrical characterization, atomic force
microscopy and Raman spectroscopy we show that the irradiation leads to
significant changes of structural and electrical properties. At the highest
fluence of 4 x 102^11 ions/cm^2, the MoS2 transistor is destroyed, while the
graphene based device remains operational, albeit with an inferior performance.


title:
VLT/VIMOS Observations of an Occulting Galaxy Pair: Redshifts and
  Effective Extinction Curve

abstract:
  We present VLT/VIMOS IFU observations of an occulting galaxy pair previously
discovered in HST observations. The foreground galaxy is a low-inclination
spiral disk, which causes clear attenuation features seen against the bright
bulge and disk of the background galaxy. We find redshifts of $z=0.064
\pm0.003$ and z=0.065 for the foreground and background galaxy respectively.
This relatively small difference does not rule out gravitational interaction
between the two galaxies. Emission line ratios point to a star-forming, not
AGN-dominated foreground galaxy.
  We fit the Cardelli, Clayton & Mathis (CCM) extinction law to the spectra of
individual fibres to derive slope ($R_V$) and normalization ($A_V$). The
normalization agrees with the HST attenuation map and the slope is lower than
the Milky Way relation ($R_V<3.1$), which is likely linked to the spatial
sampling of the disk. We speculate that the values of $R_V$ point to either
coherent ISM structures in the disk larger than usual ($\sim9$ kpc) or higher
starting values of $R_V$, indicative of recent processing of the dust.
  The foreground galaxy is a low stellar mass spiral ($M_* \sim 3 \times 10^9
M_\odot$) with a high dust content ($M_{\rm dust} \sim 0.5 \times 10^6
M_\odot$). The dust disk geometry visible in the HST image would explain the
observed SED properties of smaller galaxies: a lower mean dust temperature, a
high dust-to-stellar mass ratio but relatively little optical attenuation.
Ongoing efforts to find occulting pairs with a small foreground galaxies will
show how common this geometry is.


title: Probing Anomalous HZZ Couplings at the LHeC

abstract:
  We examine the sensitivity to the couplings of the Higgs boson to neutral
gauge bosons in a model independent way at the Large Hadron electron Collider
(LHeC). We have obtained the constraints on anomalous couplings for $HZZ$
vertex via the process $e^{-}p\rightarrow e^{-}HqX$. We find the accessible
limits of the anomalous coupling $b_{Z}$ as $(-0.12,0.43)$ and $(-0.10,0.33)$,
while the limits on coupling $\beta_{Z}$ as ($-0.32,0.32$) and $(-0.24,0.24)$
at the electron beam energy $E_{e}=60$ GeV and $E_{e}=140$ GeV, respectively.


title: Generalized Hyperfocused Arcs in $PG(2,p)$

abstract:
  A {\em generalized hyperfocused arc} $\mathcal H $ in $PG(2,q)$ is an arc of
size $k$ with the property that the $k(k-1)/2$ secants can be blocked by a set
of $k-1$ points not belonging to the arc. We show that if $q$ is a prime and
$\mathcal H$ is a generalized hyperfocused arc of size $k$, then $k=1,2$ or 4.
Interestingly, this problem is also related to the (strong) cylinder conjecture
[Ball S.: The polynomial method in Galois geometries, in Current research
topics in Galois geometry, Chapter 5, Nova Sci. Publ., New York, (2012)
105-130], as we point out in the last section.


title: Low-energy photon and pion scattering in holographic QCD

abstract:
  Using holographic models where chiral symmetry is broken through IR b.c.'s,
we determine a novel set of relations between QCD matrix elements. In
particular, we find that the amplitudes of the three processes pi pi->pi pi,
gamma gamma->pi pi and gamma->pi pi pi involve a single scalar function h(Q^2)
given by a suitable 5D integral of the EoM Green's function. In a
phenomenological analysis of gamma gamma->pi pi we find an overall agreement
with the experimental cross section for a broad range of energy. Moreover, the
polarizabilities at low energies show a fair agreement between the holographic
approach, previous computations and experiment.


title:
Comparison of force-free coronal magnetic field modeling using vector
  fields from Hinode and Solar Dynamics Observatory

abstract:
  Photospheric magnetic vector maps from two different instruments are used to
model the nonlinear force-free coronal magnetic field above an active region.
We use vector maps inferred from polarization measurements of the Solar
Dynamics Observatory/Helioseismic and Magnetic Imager (HMI) and the Solar
Optical Telescope Spectropolarimeter (SP) aboard Hinode. Besides basing our
model calculations on HMI data, we use both, SP data of original resolution and
scaled down to the resolution of HMI. This allows us to compare the model
results based on data from different instruments and to investigate how a
binning of high-resolution data effects the model outcome. The resulting 3D
magnetic fields are compared in terms of magnetic energy content and magnetic
topology. We find stronger magnetic fields in the SP data, translating into a
higher total magnetic energy of the SP models. The net Lorentz forces of the
HMI and SP lower boundaries verify their force-free compatibility. We find
substantial differences in the absolute estimates of the magnetic field energy
but similar relative estimates, e.g., the fraction of excess energy and of the
flux shared by distinct areas. The location and extension of neighboring
connectivity domains differs and the SP model fields tend to be higher and more
vertical. Hence, conclusions about the magnetic connectivity based on
force-free field models are to be drawn with caution. We find that the
deviations of the model solution when based on the lower-resolution SP data are
small compared to the differences of the solutions based on data from different
instruments.


title:
Orientational "Kerr effect" and phase modulation of light in
  deformed-helix ferroelectric liquid crystals with subwavelength pitch

abstract:
  We study both theoretically and experimentally the electro-optical properties
of vertically aligned deformed helix ferroelectric liquid crystals (VADHFLC)
with subwavelength pitch that are governed by the electrically induced optical
biaxiality of the smectic helical structure. The key theoretical result is that
the principal refractive indices of homogenized VADHFLC cells exhibit the
quadratic nonlinearity and such behavior might be interpreted as the
orientational "Kerr effect" caused by the electric-field-induced orientational
distortions of the FLC helix. In our experiments, it has been observed that,
for sufficiently weak electric fields, the magnitude of biaxiality is
proportional to the square of electric field in good agreement with our
theoretical results for the effective dielectric tensor of VADHFLCs. Under
certain conditions, the 2$\pi$ phase modulation of light, which is caused by
one of the induced refractive indices, is observed without changes in
ellipticity of incident light.


title:
Evolution of Helical Cosmic Magnetic Fields as Predicted by
  Magnetohydrodynamic Closure Theory

abstract:
  We extend our recent derivation of the time evolution equations for the
energy content of magnetic fields and turbulent motions for incompressible,
homogeneous, and isotropic turbulence to include the case of nonvanishing
helicity. These equations are subsequently numerically integrated in order to
predict the present day primordial magnetic field strength and correlation
length, depending on its initial helicity and magnetic energy density. We find
that all prior analytic predictions for helical magnetic fields, such as the
epoch when they become maximally helical and their subsequent growth of
correlation length L ~ a^{1/3} and decrease of magnetic field strength B ~
a^{-1/3} with scale factor a, are well confirmed by the simulations. An
initially fully helical primordial magnetic field is a factor 4 10^4 stronger
at the present epoch then its nonhelical counterpart when generated during the
electroweak epoch.


title: On model structure for coreflective subcategories of a model category

abstract:
  Let $\bf C$ be a coreflective subcategory of a cofibrantly generated model
category $\bf D$. In this paper we show that under suitable conditions $\bf C$
admits a cofibrantly generated model structure which is left Quillen adjunct to
the model structure on $\bf D$. As an application, we prove that well-known
convenient categories of topological spaces, such as $k$-spaces, compactly
generated spaces, and $\Delta$-generated spaces \cite{DN} (called numerically
generated in \cite{KKH}) admit a finitely generated model structure which is
Quillen equivalent to the standard model structure on the category $\bf Top$ of
topological spaces.


title: The Rise and Fall of R&D Networks

abstract:
  Drawing on a large database of publicly announced R&D alliances, we
empirically investigate the evolution of R&D networks and the process of
alliance formation in several manufacturing sectors over a 24-year period
(1986-2009). Our goal is to empirically evaluate the temporal and sectoral
robustness of a large set of network indicators, thus providing a more complete
description of R&D networks with respect to the existing literature. We find
that most network properties are not only invariant across sectors, but also
independent of the scale of aggregation at which they are observed, and we
highlight the presence of core-periphery architectures in explaining some
properties emphasized in previous empirical studies (e.g. asymmetric degree
distributions and small worlds). In addition, we show that many properties of
R&D networks are characterized by a rise-and-fall dynamics with a peak in the
mid-nineties. We find that such dynamics is driven by mechanisms of
accumulative advantage, structural homophily and multiconnectivity. In
particular, the change from the "rise" to the "fall" phase is associated to a
structural break in the importance of multiconnectivity.


title:
DCA$^+$: Dynamical Cluster Approximation with continuous lattice
  self-energy

abstract:
  The dynamical cluster approximation (DCA) is a systematic extension beyond
the single site approximation in dynamical mean field theory (DMFT), to include
spatially non-local correlations in quantum many-body simulations of strongly
correlated systems. We extend the DCA with a continuous lattice self-energy in
oder to achieve better convergence with cluster size. The new method, which we
call DCA$^+$, cures the cluster shape dependence problems of the DCA, without
suffering from causality violations of previous attempts to interpolate the
cluster self-energy. A practical approach based on standard inference
techniques is given to deduce the continuous lattice self-energy from an
interpolated cluster self-energy. We study the pseudogap region of a hole-doped
two-dimensional Hubbard model and find that in the DCA$^+$ algorithm, the
self-energy and pseudo-gap temperature $T^*$ converge monotonously with cluster
size. Introduction of a continuous lattice self-energy eliminates artificial
long-rage correlations and thus significantly reduces the sign problem of the
quantum Monte Carlo cluster solver in the DCA$^+$ algorithm compared to the
normal DCA. Simulations with much larger cluster sizes thus become feasible,
which, along with the improved convergence in cluster size, raises hope that
precise extrapolations to the exact infinite cluster size limit can be reached
for other physical quantities as well.


title: On completions of algebras in SNr_nCA_{n+k}, n\geq 3, k\geq 1

abstract:
  We give a sufficient condition that implies that SNr_nCA_{n+k}, n\geq 3,
k\geq 3 (both finite)is not closed under completions. We compare this condition
to existing results in literature.


title: Central limit theorems for an Indian buffet model with random weights

abstract:
  The three-parameter Indian buffet process is generalized. The possibly
different role played by customers is taken into account by suitable (random)
weights. Various limit theorems are also proved for such generalized Indian
buffet process. Let $L_n$ be the number of dishes experimented by the first $n$
customers, and let $\overline{K}_n=(1/n)\sum_{i=1}^nK_i$ where $K_i$ is the
number of dishes tried by customer $i$. The asymptotic distributions of $L_n$
and $\overline{K}_n$, suitably centered and scaled, are obtained. The
convergence turns out to be stable (and not only in distribution). As a
particular case, the results apply to the standard (i.e., nongeneralized)
Indian buffet process.